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lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
rhashtable: Use a single bucket lock for sibling buckets rhashtable currently allows to use a bucket lock per bucket. This requires multiple levels of complicated nested locking because when resizing, a single bucket of the smaller table will map to two buckets in the larger table. So far rhashtable has explicitly locked both buckets in the larger table. By excluding the highest bit of the hash from the bucket lock map and thus only allowing locks to buckets in a ratio of 1:2, the locking can be simplified a lot without losing the benefits of multiple locks. Larger tables which benefit from multiple locks will not have a single lock per bucket anyway. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-05 02:03:32 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add cap on number of elements in hash table We currently have no limit on the number of elements in a hash table. This is a problem because some users (tipc) set a ceiling on the maximum table size and when that is reached the hash table may degenerate. Others may encounter OOM when growing and if we allow insertions when that happens the hash table perofrmance may also suffer. This patch adds a new paramater insecure_max_entries which becomes the cap on the table. If unset it defaults to max_size * 2. If it is also zero it means that there is no cap on the number of elements in the table. However, the table will grow whenever the utilisation hits 100% and if that growth fails, you will get ENOMEM on insertion. As allowing oversubscription is potentially dangerous, the name contains the word insecure. Note that the cap is not a hard limit. This is done for performance reasons as enforcing a hard limit will result in use of atomic ops that are heavier than the ones we currently use. The reasoning is that we're only guarding against a gross over- subscription of the table, rather than a small breach of the limit. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-15 11:30:47 +08:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: use cond_resched() If a hash table has 128 slots and 16384 elems, expand to 256 slots takes more than one second. For larger sets, a soft lockup is detected. Holding cpu for that long, even in a work queue is a show stopper for non preemptable kernels. cond_resched() at strategic points to allow process scheduler to reschedule us. Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Daniel Borkmann <daniel@iogearbox.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-26 07:20:34 -08:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
net: replace remaining users of arch_fast_hash with jhash This patch effectively reverts commit 500f80872645 ("net: ovs: use CRC32 accelerated flow hash if available"), and other remaining arch_fast_hash() users such as from nfsd via commit 6282cd565553 ("NFSD: Don't hand out delegations for 30 seconds after recalling them.") where it has been used as a hash function for bloom filtering. While we think that these users are actually not much of concern, it has been requested to remove the arch_fast_hash() library bits that arose from [1] entirely as per recent discussion [2]. The main argument is that using it as a hash may introduce bias due to its linearity (see avalanche criterion) and thus makes it less clear (though we tried to document that) when this security/performance trade-off is actually acceptable for a general purpose library function. Lets therefore avoid any further confusion on this matter and remove it to prevent any future accidental misuse of it. For the time being, this is going to make hashing of flow keys a bit more expensive in the ovs case, but future work could reevaluate a different hashing discipline. [1] https://patchwork.ozlabs.org/patch/299369/ [2] https://patchwork.ozlabs.org/patch/418756/ Cc: Neil Brown <neilb@suse.de> Cc: Francesco Fusco <fusco@ntop.org> Cc: Jesse Gross <jesse@nicira.com> Cc: Thomas Graf <tgraf@suug.ch> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-10 16:33:11 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: using ERR_PTR requires linux/err.h Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-09 14:04:03 +11:00
rhashtable: add missing import <linux/export.h> rhashtable uses EXPORT_SYMBOL_GPL() without importing linux/export.h directly it is only imported indirectly through some other includes. Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-06-06 22:07:23 +02:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Introduce max_size/min_size This patch adds the parameters max_size and min_size which are meant to replace max_shift and min_shift. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-18 20:01:16 +11:00
rhashtable: avoid large lock-array allocations Sander reports following splat after netfilter nat bysrc table got converted to rhashtable: swapper/0: page allocation failure: order:3, mode:0x2084020(GFP_ATOMIC|__GFP_COMP) CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.8.0-rc1 [..] [<ffffffff811633ed>] warn_alloc_failed+0xdd/0x140 [<ffffffff811638b1>] __alloc_pages_nodemask+0x3e1/0xcf0 [<ffffffff811a72ed>] alloc_pages_current+0x8d/0x110 [<ffffffff8117cb7f>] kmalloc_order+0x1f/0x70 [<ffffffff811aec19>] __kmalloc+0x129/0x140 [<ffffffff8146d561>] bucket_table_alloc+0xc1/0x1d0 [<ffffffff8146da1d>] rhashtable_insert_rehash+0x5d/0xe0 [<ffffffff819fcfff>] nf_nat_setup_info+0x2ef/0x400 The failure happens when allocating the spinlock array. Even with GFP_KERNEL its unlikely for such a large allocation to succeed. Thomas Graf pointed me at inet_ehash_locks_alloc(), so in addition to adding NOWARN for atomic allocations this also makes the bucket-array sizing more conservative. In commit 095dc8e0c3686 ("tcp: fix/cleanup inet_ehash_locks_alloc()"), Eric Dumazet says: "Budget 2 cache lines per cpu worth of 'spinlocks'". IOW, consider size needed by a single spinlock when determining number of locks per cpu. So with 64 byte per cacheline and 4 byte per spinlock this gives 32 locks per cpu. Resulting size of the lock-array (sizeof(spinlock) == 4): cpus: 1 2 4 8 16 32 64 old: 1k 1k 4k 8k 16k 16k 16k new: 128 256 512 1k 2k 4k 8k 8k allocation should have decent chance of success even with GFP_ATOMIC, and should not fail with GFP_KERNEL. With 72-byte spinlock (LOCKDEP): cpus : 1 2 old: 9k 18k new: ~2k ~4k Reported-by: Sander Eikelenboom <linux@eikelenboom.it> Suggested-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-12 12:03:52 +02:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Move hash_rnd into bucket_table Currently hash_rnd is a parameter that users can set. However, no existing users set this parameter. It is also something that people are unlikely to want to set directly since it's just a random number. In preparation for allowing the reseeding/rehashing of rhashtable, this patch moves hash_rnd into bucket_table so that it's now an internal state rather than a parameter. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-10 09:27:55 +11:00
rhashtable: Do hashing inside of rhashtable_lookup_compare() Hash the key inside of rhashtable_lookup_compare() like rhashtable_lookup() does. This allows to simplify the hashing functions and keep them private. Signed-off-by: Thomas Graf <tgraf@suug.ch> Cc: netfilter-devel@vger.kernel.org Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:14 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Dump bucket tables on locking violation under PROVE_LOCKING This simplifies debugging of locking violations if compiled with CONFIG_PROVE_LOCKING. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-05 02:03:34 +01:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
rhashtable: Dump bucket tables on locking violation under PROVE_LOCKING This simplifies debugging of locking violations if compiled with CONFIG_PROVE_LOCKING. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-05 02:03:34 +01:00
rhashtable: Allow GFP_ATOMIC bucket table allocation This patch adds the ability to allocate bucket table with GFP_ATOMIC instead of GFP_KERNEL. This is needed when we perform an immediate rehash during insertion. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:27 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: avoid large lock-array allocations Sander reports following splat after netfilter nat bysrc table got converted to rhashtable: swapper/0: page allocation failure: order:3, mode:0x2084020(GFP_ATOMIC|__GFP_COMP) CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.8.0-rc1 [..] [<ffffffff811633ed>] warn_alloc_failed+0xdd/0x140 [<ffffffff811638b1>] __alloc_pages_nodemask+0x3e1/0xcf0 [<ffffffff811a72ed>] alloc_pages_current+0x8d/0x110 [<ffffffff8117cb7f>] kmalloc_order+0x1f/0x70 [<ffffffff811aec19>] __kmalloc+0x129/0x140 [<ffffffff8146d561>] bucket_table_alloc+0xc1/0x1d0 [<ffffffff8146da1d>] rhashtable_insert_rehash+0x5d/0xe0 [<ffffffff819fcfff>] nf_nat_setup_info+0x2ef/0x400 The failure happens when allocating the spinlock array. Even with GFP_KERNEL its unlikely for such a large allocation to succeed. Thomas Graf pointed me at inet_ehash_locks_alloc(), so in addition to adding NOWARN for atomic allocations this also makes the bucket-array sizing more conservative. In commit 095dc8e0c3686 ("tcp: fix/cleanup inet_ehash_locks_alloc()"), Eric Dumazet says: "Budget 2 cache lines per cpu worth of 'spinlocks'". IOW, consider size needed by a single spinlock when determining number of locks per cpu. So with 64 byte per cacheline and 4 byte per spinlock this gives 32 locks per cpu. Resulting size of the lock-array (sizeof(spinlock) == 4): cpus: 1 2 4 8 16 32 64 old: 1k 1k 4k 8k 16k 16k 16k new: 128 256 512 1k 2k 4k 8k 8k allocation should have decent chance of success even with GFP_ATOMIC, and should not fail with GFP_KERNEL. With 72-byte spinlock (LOCKDEP): cpus : 1 2 old: 9k 18k new: ~2k ~4k Reported-by: Sander Eikelenboom <linux@eikelenboom.it> Suggested-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-12 12:03:52 +02:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Use a single bucket lock for sibling buckets rhashtable currently allows to use a bucket lock per bucket. This requires multiple levels of complicated nested locking because when resizing, a single bucket of the smaller table will map to two buckets in the larger table. So far rhashtable has explicitly locked both buckets in the larger table. By excluding the highest bit of the hash from the bucket lock map and thus only allowing locks to buckets in a ratio of 1:2, the locking can be simplified a lot without losing the benefits of multiple locks. Larger tables which benefit from multiple locks will not have a single lock per bucket anyway. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-05 02:03:32 +01:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: fix a memory leak in alloc_bucket_locks() If vmalloc() was successful, do not attempt a kmalloc_array() Fixes: 4cf0b354d92e ("rhashtable: avoid large lock-array allocations") Reported-by: CAI Qian <caiqian@redhat.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Florian Westphal <fw@strlen.de> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: CAI Qian <caiqian@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-26 08:51:39 -07:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Allow GFP_ATOMIC bucket table allocation This patch adds the ability to allocate bucket table with GFP_ATOMIC instead of GFP_KERNEL. This is needed when we perform an immediate rehash during insertion. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:27 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: avoid large lock-array allocations Sander reports following splat after netfilter nat bysrc table got converted to rhashtable: swapper/0: page allocation failure: order:3, mode:0x2084020(GFP_ATOMIC|__GFP_COMP) CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.8.0-rc1 [..] [<ffffffff811633ed>] warn_alloc_failed+0xdd/0x140 [<ffffffff811638b1>] __alloc_pages_nodemask+0x3e1/0xcf0 [<ffffffff811a72ed>] alloc_pages_current+0x8d/0x110 [<ffffffff8117cb7f>] kmalloc_order+0x1f/0x70 [<ffffffff811aec19>] __kmalloc+0x129/0x140 [<ffffffff8146d561>] bucket_table_alloc+0xc1/0x1d0 [<ffffffff8146da1d>] rhashtable_insert_rehash+0x5d/0xe0 [<ffffffff819fcfff>] nf_nat_setup_info+0x2ef/0x400 The failure happens when allocating the spinlock array. Even with GFP_KERNEL its unlikely for such a large allocation to succeed. Thomas Graf pointed me at inet_ehash_locks_alloc(), so in addition to adding NOWARN for atomic allocations this also makes the bucket-array sizing more conservative. In commit 095dc8e0c3686 ("tcp: fix/cleanup inet_ehash_locks_alloc()"), Eric Dumazet says: "Budget 2 cache lines per cpu worth of 'spinlocks'". IOW, consider size needed by a single spinlock when determining number of locks per cpu. So with 64 byte per cacheline and 4 byte per spinlock this gives 32 locks per cpu. Resulting size of the lock-array (sizeof(spinlock) == 4): cpus: 1 2 4 8 16 32 64 old: 1k 1k 4k 8k 16k 16k 16k new: 128 256 512 1k 2k 4k 8k 8k allocation should have decent chance of success even with GFP_ATOMIC, and should not fail with GFP_KERNEL. With 72-byte spinlock (LOCKDEP): cpus : 1 2 old: 9k 18k new: ~2k ~4k Reported-by: Sander Eikelenboom <linux@eikelenboom.it> Suggested-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-12 12:03:52 +02:00
rhashtable: fix a memory leak in alloc_bucket_locks() If vmalloc() was successful, do not attempt a kmalloc_array() Fixes: 4cf0b354d92e ("rhashtable: avoid large lock-array allocations") Reported-by: CAI Qian <caiqian@redhat.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Florian Westphal <fw@strlen.de> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: CAI Qian <caiqian@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-26 08:51:39 -07:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Free bucket tables asynchronously after rehash There is in fact no need to wait for an RCU grace period in the rehash function, since all insertions are guaranteed to go into the new table through spin locks. This patch uses call_rcu to free the old/rehashed table at our leisure. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:23 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Allow GFP_ATOMIC bucket table allocation This patch adds the ability to allocate bucket table with GFP_ATOMIC instead of GFP_KERNEL. This is needed when we perform an immediate rehash during insertion. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:27 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: better high order allocation attempts When trying to allocate future tables via bucket_table_alloc(), it seems overkill on large table shifts that we probe for kzalloc() unconditionally first, as it's likely to fail. Only probe with kzalloc() for more reasonable table sizes and use vzalloc() either as a fallback on failure or directly in case of large table sizes. Fixes: 7e1e77636e36 ("lib: Resizable, Scalable, Concurrent Hash Table") Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-20 00:53:38 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Supports for nulls marker In order to allow for wider usage of rhashtable, use a special nulls marker to terminate each chain. The reason for not using the existing nulls_list is that the prev pointer usage would not be valid as entries can be linked in two different buckets at the same time. The 4 nulls base bits can be set through the rhashtable_params structure like this: struct rhashtable_params params = { [...] .nulls_base = (1U << RHT_BASE_SHIFT), }; This reduces the hash length from 32 bits to 27 bits. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:21 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Allow GFP_ATOMIC bucket table allocation This patch adds the ability to allocate bucket table with GFP_ATOMIC instead of GFP_KERNEL. This is needed when we perform an immediate rehash during insertion. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:27 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Allow GFP_ATOMIC bucket table allocation This patch adds the ability to allocate bucket table with GFP_ATOMIC instead of GFP_KERNEL. This is needed when we perform an immediate rehash during insertion. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:27 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Move seed init into bucket_table_alloc It seems that I have already made every rehash redo the random seed even though my commit message indicated otherwise :) Since we have already taken that step, this patch goes one step further and moves the seed initialisation into bucket_table_alloc. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:22 +11:00
rhashtable: Supports for nulls marker In order to allow for wider usage of rhashtable, use a special nulls marker to terminate each chain. The reason for not using the existing nulls_list is that the prev pointer usage would not be valid as entries can be linked in two different buckets at the same time. The 4 nulls base bits can be set through the rhashtable_params structure like this: struct rhashtable_params params = { [...] .nulls_base = (1U << RHT_BASE_SHIFT), }; This reduces the hash length from 32 bits to 27 bits. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:21 +01:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Use 'unsigned int' consistently Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:17 +01:00
rhashtable: Use a single bucket lock for sibling buckets rhashtable currently allows to use a bucket lock per bucket. This requires multiple levels of complicated nested locking because when resizing, a single bucket of the smaller table will map to two buckets in the larger table. So far rhashtable has explicitly locked both buckets in the larger table. By excluding the highest bit of the hash from the bucket lock map and thus only allowing locks to buckets in a ratio of 1:2, the locking can be simplified a lot without losing the benefits of multiple locks. Larger tables which benefit from multiple locks will not have a single lock per bucket anyway. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-05 02:03:32 +01:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Use 'unsigned int' consistently Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:17 +01:00
rhashtable: Use a single bucket lock for sibling buckets rhashtable currently allows to use a bucket lock per bucket. This requires multiple levels of complicated nested locking because when resizing, a single bucket of the smaller table will map to two buckets in the larger table. So far rhashtable has explicitly locked both buckets in the larger table. By excluding the highest bit of the hash from the bucket lock map and thus only allowing locks to buckets in a ratio of 1:2, the locking can be simplified a lot without losing the benefits of multiple locks. Larger tables which benefit from multiple locks will not have a single lock per bucket anyway. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-05 02:03:32 +01:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Use a single bucket lock for sibling buckets rhashtable currently allows to use a bucket lock per bucket. This requires multiple levels of complicated nested locking because when resizing, a single bucket of the smaller table will map to two buckets in the larger table. So far rhashtable has explicitly locked both buckets in the larger table. By excluding the highest bit of the hash from the bucket lock map and thus only allowing locks to buckets in a ratio of 1:2, the locking can be simplified a lot without losing the benefits of multiple locks. Larger tables which benefit from multiple locks will not have a single lock per bucket anyway. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-05 02:03:32 +01:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Use a single bucket lock for sibling buckets rhashtable currently allows to use a bucket lock per bucket. This requires multiple levels of complicated nested locking because when resizing, a single bucket of the smaller table will map to two buckets in the larger table. So far rhashtable has explicitly locked both buckets in the larger table. By excluding the highest bit of the hash from the bucket lock map and thus only allowing locks to buckets in a ratio of 1:2, the locking can be simplified a lot without losing the benefits of multiple locks. Larger tables which benefit from multiple locks will not have a single lock per bucket anyway. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-05 02:03:32 +01:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Use SINGLE_DEPTH_NESTING We only nest one level deep there is no need to roll our own subclasses. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:21 +11:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
lib: fix data race in rhashtable_rehash_one rhashtable_rehash_one() uses complex logic to update entry->next field, after INIT_RHT_NULLS_HEAD and NULLS_MARKER expansion: entry->next = 1 | ((base + off) << 1) This can be compiled along the lines of: entry->next = base + off entry->next <<= 1 entry->next |= 1 Which will break concurrent readers. NULLS value recomputation is not needed here, so just remove the complex logic. The data race was found with KernelThreadSanitizer (KTSAN). Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Acked-by: Eric Dumazet <edumazet@google.com> Acked-by: Thomas Graf <tgraf@suug.ch> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-09-22 10:51:52 +02:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Use 'unsigned int' consistently Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:17 +01:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Add more lock verification Catch hash miscalculations which result in hard to track down race conditions. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-05 02:03:35 +01:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Add rehash counter to bucket_table This patch adds a rehash counter to bucket_table to indicate the last bucket that has been rehashed. This serves two purposes: 1. Any bucket that has been rehashed can never gain a new object. 2. If the rehash counter reaches the size of the table, the table will forever remain empty. This patch also downsizes bucket_table->size to an unsigned int since we do not support sizes greater than 32 bits yet. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:24 +11:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Move future_tbl into struct bucket_table This patch moves future_tbl to open up the possibility of having multiple rehashes on the same table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:25 +11:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Use 'unsigned int' consistently Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:17 +01:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Fix sleeping inside RCU critical section in walk_stop The commit 963ecbd41a1026d99ec7537c050867428c397b89 ("rhashtable: Fix use-after-free in rhashtable_walk_stop") fixed a real bug but created another one because we may end up sleeping inside an RCU critical section. This patch fixes it properly by replacing the mutex with a spin lock that specifically protects the walker lists. Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 09:53:17 +11:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Fix sleeping inside RCU critical section in walk_stop The commit 963ecbd41a1026d99ec7537c050867428c397b89 ("rhashtable: Fix use-after-free in rhashtable_walk_stop") fixed a real bug but created another one because we may end up sleeping inside an RCU critical section. This patch fixes it properly by replacing the mutex with a spin lock that specifically protects the walker lists. Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 09:53:17 +11:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
rhashtable: Free bucket tables asynchronously after rehash There is in fact no need to wait for an RCU grace period in the rehash function, since all insertions are guaranteed to go into the new table through spin locks. This patch uses call_rcu to free the old/rehashed table at our leisure. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:23 +11:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add arbitrary rehash function This patch adds a rehash function that supports the use of any hash function for the new table. This is needed to support changing the random seed value during the lifetime of the hash table. However for now the random seed value is still constant and the rehash function is simply used to replace the existing expand/shrink functions. [ ASSERT_BUCKET_LOCK() and thus debug_dump_table() + debug_dump_buckets() are not longer used, so delete them entirely. -DaveM ] Signed-off-by: Herbert Xu <herbert.xu@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-11 09:43:48 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Allow GFP_ATOMIC bucket table allocation This patch adds the ability to allocate bucket table with GFP_ATOMIC instead of GFP_KERNEL. This is needed when we perform an immediate rehash during insertion. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:27 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Shrink to fit This patch changes rhashtable_shrink to shrink to the smallest size possible rather than halving the table. This is needed because with multiple rehashing we will defer shrinking until all other rehashing is done, meaning that when we do shrink we may be able to shrink a lot. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:25 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: kill ht->shift atomic operations Commit c0c09bfdc415 ("rhashtable: avoid unnecessary wakeup for worker queue") changed ht->shift to be atomic, which is actually unnecessary. Instead of leaving the current shift in the core rhashtable structure, it can be cached inside the individual bucket tables. There, it will only be initialized once during a new table allocation in the shrink/expansion slow path, and from then onward it stays immutable for the rest of the bucket table liftime. That allows shift to be non-atomic. The patch also moves hash_rnd management into the table setup. The rhashtable structure now consumes 3 instead of 4 cachelines. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Ying Xue <ying.xue@windriver.com> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-12 15:28:40 +01:00
rhashtable: fix shift by 64 when shrinking I got this: ================================================================================ UBSAN: Undefined behaviour in ./include/linux/log2.h:63:13 shift exponent 64 is too large for 64-bit type 'long unsigned int' CPU: 1 PID: 721 Comm: kworker/1:1 Not tainted 4.8.0-rc1+ #87 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 Workqueue: events rht_deferred_worker 0000000000000000 ffff88011661f8d8 ffffffff82344f50 0000000041b58ab3 ffffffff84f98000 ffffffff82344ea4 ffff88011661f900 ffff88011661f8b0 0000000000000001 ffff88011661f6b8 dffffc0000000000 ffffffff867f7640 Call Trace: [<ffffffff82344f50>] dump_stack+0xac/0xfc [<ffffffff82344ea4>] ? _atomic_dec_and_lock+0xc4/0xc4 [<ffffffff8242f5b8>] ubsan_epilogue+0xd/0x8a [<ffffffff82430c41>] __ubsan_handle_shift_out_of_bounds+0x255/0x29a [<ffffffff824309ec>] ? __ubsan_handle_out_of_bounds+0x180/0x180 [<ffffffff84003436>] ? nl80211_req_set_reg+0x256/0x2f0 [<ffffffff812112ba>] ? print_context_stack+0x8a/0x160 [<ffffffff81200031>] ? amd_pmu_reset+0x341/0x380 [<ffffffff823af808>] rht_deferred_worker+0x1618/0x1790 [<ffffffff823af808>] ? rht_deferred_worker+0x1618/0x1790 [<ffffffff823ae1f0>] ? rhashtable_jhash2+0x370/0x370 [<ffffffff8134c12d>] ? process_one_work+0x6fd/0x1970 [<ffffffff8134c1cf>] process_one_work+0x79f/0x1970 [<ffffffff8134c12d>] ? process_one_work+0x6fd/0x1970 [<ffffffff8134ba30>] ? try_to_grab_pending+0x4c0/0x4c0 [<ffffffff8134d564>] ? worker_thread+0x1c4/0x1340 [<ffffffff8134d8ff>] worker_thread+0x55f/0x1340 [<ffffffff845e904f>] ? __schedule+0x4df/0x1d40 [<ffffffff8134d3a0>] ? process_one_work+0x1970/0x1970 [<ffffffff8134d3a0>] ? process_one_work+0x1970/0x1970 [<ffffffff813642f7>] kthread+0x237/0x390 [<ffffffff813640c0>] ? __kthread_parkme+0x280/0x280 [<ffffffff845f8c93>] ? _raw_spin_unlock_irq+0x33/0x50 [<ffffffff845f95df>] ret_from_fork+0x1f/0x40 [<ffffffff813640c0>] ? __kthread_parkme+0x280/0x280 ================================================================================ roundup_pow_of_two() is undefined when called with an argument of 0, so let's avoid the call and just fall back to ht->p.min_size (which should never be smaller than HASH_MIN_SIZE). Cc: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-12 20:10:44 +02:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: fix shift by 64 when shrinking I got this: ================================================================================ UBSAN: Undefined behaviour in ./include/linux/log2.h:63:13 shift exponent 64 is too large for 64-bit type 'long unsigned int' CPU: 1 PID: 721 Comm: kworker/1:1 Not tainted 4.8.0-rc1+ #87 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.9.3-0-ge2fc41e-prebuilt.qemu-project.org 04/01/2014 Workqueue: events rht_deferred_worker 0000000000000000 ffff88011661f8d8 ffffffff82344f50 0000000041b58ab3 ffffffff84f98000 ffffffff82344ea4 ffff88011661f900 ffff88011661f8b0 0000000000000001 ffff88011661f6b8 dffffc0000000000 ffffffff867f7640 Call Trace: [<ffffffff82344f50>] dump_stack+0xac/0xfc [<ffffffff82344ea4>] ? _atomic_dec_and_lock+0xc4/0xc4 [<ffffffff8242f5b8>] ubsan_epilogue+0xd/0x8a [<ffffffff82430c41>] __ubsan_handle_shift_out_of_bounds+0x255/0x29a [<ffffffff824309ec>] ? __ubsan_handle_out_of_bounds+0x180/0x180 [<ffffffff84003436>] ? nl80211_req_set_reg+0x256/0x2f0 [<ffffffff812112ba>] ? print_context_stack+0x8a/0x160 [<ffffffff81200031>] ? amd_pmu_reset+0x341/0x380 [<ffffffff823af808>] rht_deferred_worker+0x1618/0x1790 [<ffffffff823af808>] ? rht_deferred_worker+0x1618/0x1790 [<ffffffff823ae1f0>] ? rhashtable_jhash2+0x370/0x370 [<ffffffff8134c12d>] ? process_one_work+0x6fd/0x1970 [<ffffffff8134c1cf>] process_one_work+0x79f/0x1970 [<ffffffff8134c12d>] ? process_one_work+0x6fd/0x1970 [<ffffffff8134ba30>] ? try_to_grab_pending+0x4c0/0x4c0 [<ffffffff8134d564>] ? worker_thread+0x1c4/0x1340 [<ffffffff8134d8ff>] worker_thread+0x55f/0x1340 [<ffffffff845e904f>] ? __schedule+0x4df/0x1d40 [<ffffffff8134d3a0>] ? process_one_work+0x1970/0x1970 [<ffffffff8134d3a0>] ? process_one_work+0x1970/0x1970 [<ffffffff813642f7>] kthread+0x237/0x390 [<ffffffff813640c0>] ? __kthread_parkme+0x280/0x280 [<ffffffff845f8c93>] ? _raw_spin_unlock_irq+0x33/0x50 [<ffffffff845f95df>] ret_from_fork+0x1f/0x40 [<ffffffff813640c0>] ? __kthread_parkme+0x280/0x280 ================================================================================ roundup_pow_of_two() is undefined when called with an argument of 0, so let's avoid the call and just fall back to ht->p.min_size (which should never be smaller than HASH_MIN_SIZE). Cc: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-08-12 20:10:44 +02:00
rhashtable: Shrink to fit This patch changes rhashtable_shrink to shrink to the smallest size possible rather than halving the table. This is needed because with multiple rehashing we will defer shrinking until all other rehashing is done, meaning that when we do shrink we may be able to shrink a lot. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:25 +11:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Allow GFP_ATOMIC bucket table allocation This patch adds the ability to allocate bucket table with GFP_ATOMIC instead of GFP_KERNEL. This is needed when we perform an immediate rehash during insertion. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:27 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Fix race in rhashtable_destroy() and use regular work_struct When we put our declared work task in the global workqueue with schedule_delayed_work(), its delay parameter is always zero. Therefore, we should define a regular work in rhashtable structure instead of a delayed work. By the way, we add a condition to check whether resizing functions are NULL before cancelling the work, avoiding to cancel an uninitialized work. Lastly, while we wait for all work items we submitted before to run to completion with cancel_delayed_work(), ht->mutex has been taken in rhashtable_destroy(). Moreover, cancel_delayed_work() doesn't return until all work items are accomplished, and when work items are scheduled, the work's function - rht_deferred_worker() will be called. However, as rht_deferred_worker() also needs to acquire the lock, deadlock might happen at the moment as the lock is already held before. So if the cancel work function is moved out of the lock covered scope, this will avoid the deadlock. Fixes: 97defe1 ("rhashtable: Per bucket locks & deferred expansion/shrinking") Signed-off-by: Ying Xue <ying.xue@windriver.com> Cc: Thomas Graf <tgraf@suug.ch> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-16 11:13:09 +08:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Fix potential crash on destroy in rhashtable_shrink The current being_destroyed check in rhashtable_expand is not enough since if we start a shrinking process after freeing all elements in the table that's also going to crash. This patch adds a being_destroyed check to the deferred worker thread so that we bail out as soon as we take the lock. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:22 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: kill ht->shift atomic operations Commit c0c09bfdc415 ("rhashtable: avoid unnecessary wakeup for worker queue") changed ht->shift to be atomic, which is actually unnecessary. Instead of leaving the current shift in the core rhashtable structure, it can be cached inside the individual bucket tables. There, it will only be initialized once during a new table allocation in the shrink/expansion slow path, and from then onward it stays immutable for the rest of the bucket table liftime. That allows shift to be non-atomic. The patch also moves hash_rnd management into the table setup. The rhashtable structure now consumes 3 instead of 4 cachelines. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Ying Xue <ying.xue@windriver.com> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-12 15:28:40 +01:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Disable automatic shrinking by default Introduce a new bool automatic_shrinking to require the user to explicitly opt-in to automatic shrinking of tables. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 20:42:19 +00:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Use 'unsigned int' consistently Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:17 +01:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Use 'unsigned int' consistently Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:17 +01:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Prevent spurious EBUSY errors on insertion Thomas and Phil observed that under stress rhashtable insertion sometimes failed with EBUSY, even though this error should only ever been seen when we're under attack and our hash chain length has grown to an unacceptable level, even after a rehash. It turns out that the logic for detecting whether there is an existing rehash is faulty. In particular, when two threads both try to grow the same table at the same time, one of them may see the newly grown table and thus erroneously conclude that it had been rehashed. This is what leads to the EBUSY error. This patch fixes this by remembering the current last table we used during insertion so that rhashtable_insert_rehash can detect when another thread has also done a resize/rehash. When this is detected we will give up our resize/rehash and simply retry the insertion with the new table. Reported-by: Thomas Graf <tgraf@suug.ch> Reported-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: Phil Sutter <phil@nwl.cc> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-03 20:41:29 +08:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Prevent spurious EBUSY errors on insertion Thomas and Phil observed that under stress rhashtable insertion sometimes failed with EBUSY, even though this error should only ever been seen when we're under attack and our hash chain length has grown to an unacceptable level, even after a rehash. It turns out that the logic for detecting whether there is an existing rehash is faulty. In particular, when two threads both try to grow the same table at the same time, one of them may see the newly grown table and thus erroneously conclude that it had been rehashed. This is what leads to the EBUSY error. This patch fixes this by remembering the current last table we used during insertion so that rhashtable_insert_rehash can detect when another thread has also done a resize/rehash. When this is detected we will give up our resize/rehash and simply retry the insertion with the new table. Reported-by: Thomas Graf <tgraf@suug.ch> Reported-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: Phil Sutter <phil@nwl.cc> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-03 20:41:29 +08:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Do not schedule more than one rehash if we can't grow further The current code currently only stops inserting rehashes into the chain when no resizes are currently scheduled. As long as resizes are scheduled and while inserting above the utilization watermark, more and more rehashes will be scheduled. This lead to a perfect DoS storm with thousands of rehashes scheduled which lead to thousands of spinlocks to be taken sequentially. Instead, only allow either a series of resizes or a single rehash. Drop any further rehashes and return -EBUSY. Fixes: ccd57b1bd324 ("rhashtable: Add immediate rehash during insertion") Signed-off-by: Thomas Graf <tgraf@suug.ch> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-04-22 09:41:46 +02:00
rhashtable: Prevent spurious EBUSY errors on insertion Thomas and Phil observed that under stress rhashtable insertion sometimes failed with EBUSY, even though this error should only ever been seen when we're under attack and our hash chain length has grown to an unacceptable level, even after a rehash. It turns out that the logic for detecting whether there is an existing rehash is faulty. In particular, when two threads both try to grow the same table at the same time, one of them may see the newly grown table and thus erroneously conclude that it had been rehashed. This is what leads to the EBUSY error. This patch fixes this by remembering the current last table we used during insertion so that rhashtable_insert_rehash can detect when another thread has also done a resize/rehash. When this is detected we will give up our resize/rehash and simply retry the insertion with the new table. Reported-by: Thomas Graf <tgraf@suug.ch> Reported-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: Phil Sutter <phil@nwl.cc> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-03 20:41:29 +08:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Prevent spurious EBUSY errors on insertion Thomas and Phil observed that under stress rhashtable insertion sometimes failed with EBUSY, even though this error should only ever been seen when we're under attack and our hash chain length has grown to an unacceptable level, even after a rehash. It turns out that the logic for detecting whether there is an existing rehash is faulty. In particular, when two threads both try to grow the same table at the same time, one of them may see the newly grown table and thus erroneously conclude that it had been rehashed. This is what leads to the EBUSY error. This patch fixes this by remembering the current last table we used during insertion so that rhashtable_insert_rehash can detect when another thread has also done a resize/rehash. When this is detected we will give up our resize/rehash and simply retry the insertion with the new table. Reported-by: Thomas Graf <tgraf@suug.ch> Reported-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: Phil Sutter <phil@nwl.cc> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-03 20:41:29 +08:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Prevent spurious EBUSY errors on insertion Thomas and Phil observed that under stress rhashtable insertion sometimes failed with EBUSY, even though this error should only ever been seen when we're under attack and our hash chain length has grown to an unacceptable level, even after a rehash. It turns out that the logic for detecting whether there is an existing rehash is faulty. In particular, when two threads both try to grow the same table at the same time, one of them may see the newly grown table and thus erroneously conclude that it had been rehashed. This is what leads to the EBUSY error. This patch fixes this by remembering the current last table we used during insertion so that rhashtable_insert_rehash can detect when another thread has also done a resize/rehash. When this is detected we will give up our resize/rehash and simply retry the insertion with the new table. Reported-by: Thomas Graf <tgraf@suug.ch> Reported-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: Phil Sutter <phil@nwl.cc> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-03 20:41:29 +08:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Prevent spurious EBUSY errors on insertion Thomas and Phil observed that under stress rhashtable insertion sometimes failed with EBUSY, even though this error should only ever been seen when we're under attack and our hash chain length has grown to an unacceptable level, even after a rehash. It turns out that the logic for detecting whether there is an existing rehash is faulty. In particular, when two threads both try to grow the same table at the same time, one of them may see the newly grown table and thus erroneously conclude that it had been rehashed. This is what leads to the EBUSY error. This patch fixes this by remembering the current last table we used during insertion so that rhashtable_insert_rehash can detect when another thread has also done a resize/rehash. When this is detected we will give up our resize/rehash and simply retry the insertion with the new table. Reported-by: Thomas Graf <tgraf@suug.ch> Reported-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: Phil Sutter <phil@nwl.cc> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-03 20:41:29 +08:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
rhashtable: Use 'unsigned int' consistently Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:17 +01:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
rhashtable: Add multiple rehash support This patch adds the missing bits to allow multiple rehashes. The read-side as well as remove already handle this correctly. So it's only the rehasher and insertion that need modification to handle this. Note that this patch doesn't actually enable it so for now rehashing is still only performed by the worker thread. This patch also disables the explicit expand/shrink interface because the table is meant to expand and shrink automatically, and continuing to export these interfaces unnecessarily complicates the life of the rehasher since the rehash process is now composed of two parts. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:26 +11:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
rhashtable: Add cap on number of elements in hash table We currently have no limit on the number of elements in a hash table. This is a problem because some users (tipc) set a ceiling on the maximum table size and when that is reached the hash table may degenerate. Others may encounter OOM when growing and if we allow insertions when that happens the hash table perofrmance may also suffer. This patch adds a new paramater insecure_max_entries which becomes the cap on the table. If unset it defaults to max_size * 2. If it is also zero it means that there is no cap on the number of elements in the table. However, the table will grow whenever the utilisation hits 100% and if that growth fails, you will get ENOMEM on insertion. As allowing oversubscription is potentially dangerous, the name contains the word insecure. Note that the cap is not a hard limit. This is done for performance reasons as enforcing a hard limit will result in use of atomic ops that are heavier than the ones we currently use. The reasoning is that we're only guarding against a gross over- subscription of the table, rather than a small breach of the limit. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-15 11:30:47 +08:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
rhashtable: Prevent spurious EBUSY errors on insertion Thomas and Phil observed that under stress rhashtable insertion sometimes failed with EBUSY, even though this error should only ever been seen when we're under attack and our hash chain length has grown to an unacceptable level, even after a rehash. It turns out that the logic for detecting whether there is an existing rehash is faulty. In particular, when two threads both try to grow the same table at the same time, one of them may see the newly grown table and thus erroneously conclude that it had been rehashed. This is what leads to the EBUSY error. This patch fixes this by remembering the current last table we used during insertion so that rhashtable_insert_rehash can detect when another thread has also done a resize/rehash. When this is detected we will give up our resize/rehash and simply retry the insertion with the new table. Reported-by: Thomas Graf <tgraf@suug.ch> Reported-by: Phil Sutter <phil@nwl.cc> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Tested-by: Phil Sutter <phil@nwl.cc> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-03 20:41:29 +08:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: accept GFP flags in rhashtable_walk_init In certain cases, the 802.11 mesh pathtable code wants to iterate over all of the entries in the forwarding table from the receive path, which is inside an RCU read-side critical section. Enable walks inside atomic sections by allowing GFP_ATOMIC allocations for the walker state. Change all existing callsites to pass in GFP_KERNEL. Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: Bob Copeland <me@bobcopeland.com> [also adjust gfs2/glock.c and rhashtable tests] Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2016-03-02 10:09:19 -05:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: accept GFP flags in rhashtable_walk_init In certain cases, the 802.11 mesh pathtable code wants to iterate over all of the entries in the forwarding table from the receive path, which is inside an RCU read-side critical section. Enable walks inside atomic sections by allowing GFP_ATOMIC allocations for the walker state. Change all existing callsites to pass in GFP_KERNEL. Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: Bob Copeland <me@bobcopeland.com> [also adjust gfs2/glock.c and rhashtable tests] Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2016-03-02 10:09:19 -05:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: accept GFP flags in rhashtable_walk_init In certain cases, the 802.11 mesh pathtable code wants to iterate over all of the entries in the forwarding table from the receive path, which is inside an RCU read-side critical section. Enable walks inside atomic sections by allowing GFP_ATOMIC allocations for the walker state. Change all existing callsites to pass in GFP_KERNEL. Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: Bob Copeland <me@bobcopeland.com> [also adjust gfs2/glock.c and rhashtable tests] Signed-off-by: Johannes Berg <johannes.berg@intel.com>
2016-03-02 10:09:19 -05:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: Fix walker list corruption The commit ba7c95ea3870fe7b847466d39a049ab6f156aa2c ("rhashtable: Fix sleeping inside RCU critical section in walk_stop") introduced a new spinlock for the walker list. However, it did not convert all existing users of the list over to the new spin lock. Some continued to use the old mutext for this purpose. This obviously led to corruption of the list. The fix is to use the spin lock everywhere where we touch the list. This also allows us to do rcu_rad_lock before we take the lock in rhashtable_walk_start. With the old mutex this would've deadlocked but it's safe with the new spin lock. Fixes: ba7c95ea3870 ("rhashtable: Fix sleeping inside RCU...") Reported-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-16 16:45:54 +08:00
rhashtable: Kill harmless RCU warning in rhashtable_walk_init The commit c6ff5268293ef98e48a99597e765ffc417e39fa5 ("rhashtable: Fix walker list corruption") causes a suspicious RCU usage warning because we no longer hold ht->mutex when we dereference ht->tbl. However, this is a false positive because we now hold ht->lock which also guarantees that ht->tbl won't disppear from under us. This patch kills the warning by using rcu_dereference_protected. Reported-by: kernel test robot <ying.huang@linux.intel.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-19 10:45:28 +08:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Fix walker list corruption The commit ba7c95ea3870fe7b847466d39a049ab6f156aa2c ("rhashtable: Fix sleeping inside RCU critical section in walk_stop") introduced a new spinlock for the walker list. However, it did not convert all existing users of the list over to the new spin lock. Some continued to use the old mutext for this purpose. This obviously led to corruption of the list. The fix is to use the spin lock everywhere where we touch the list. This also allows us to do rcu_rad_lock before we take the lock in rhashtable_walk_start. With the old mutex this would've deadlocked but it's safe with the new spin lock. Fixes: ba7c95ea3870 ("rhashtable: Fix sleeping inside RCU...") Reported-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-16 16:45:54 +08:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: Fix walker list corruption The commit ba7c95ea3870fe7b847466d39a049ab6f156aa2c ("rhashtable: Fix sleeping inside RCU critical section in walk_stop") introduced a new spinlock for the walker list. However, it did not convert all existing users of the list over to the new spin lock. Some continued to use the old mutext for this purpose. This obviously led to corruption of the list. The fix is to use the spin lock everywhere where we touch the list. This also allows us to do rcu_rad_lock before we take the lock in rhashtable_walk_start. With the old mutex this would've deadlocked but it's safe with the new spin lock. Fixes: ba7c95ea3870 ("rhashtable: Fix sleeping inside RCU...") Reported-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-16 16:45:54 +08:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Fix walker list corruption The commit ba7c95ea3870fe7b847466d39a049ab6f156aa2c ("rhashtable: Fix sleeping inside RCU critical section in walk_stop") introduced a new spinlock for the walker list. However, it did not convert all existing users of the list over to the new spin lock. Some continued to use the old mutext for this purpose. This obviously led to corruption of the list. The fix is to use the spin lock everywhere where we touch the list. This also allows us to do rcu_rad_lock before we take the lock in rhashtable_walk_start. With the old mutex this would've deadlocked but it's safe with the new spin lock. Fixes: ba7c95ea3870 ("rhashtable: Fix sleeping inside RCU...") Reported-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-16 16:45:54 +08:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: Annotate RCU locking of walkers Fixes the following sparse warnings: lib/rhashtable.c:767:5: warning: context imbalance in 'rhashtable_walk_start' - wrong count at exit lib/rhashtable.c:849:6: warning: context imbalance in 'rhashtable_walk_stop' - unexpected unlock Fixes: f2dba9c6ff0d ("rhashtable: Introduce rhashtable_walk_*") Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-16 10:42:27 +01:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: Fix walker list corruption The commit ba7c95ea3870fe7b847466d39a049ab6f156aa2c ("rhashtable: Fix sleeping inside RCU critical section in walk_stop") introduced a new spinlock for the walker list. However, it did not convert all existing users of the list over to the new spin lock. Some continued to use the old mutext for this purpose. This obviously led to corruption of the list. The fix is to use the spin lock everywhere where we touch the list. This also allows us to do rcu_rad_lock before we take the lock in rhashtable_walk_start. With the old mutex this would've deadlocked but it's safe with the new spin lock. Fixes: ba7c95ea3870 ("rhashtable: Fix sleeping inside RCU...") Reported-by: Colin Ian King <colin.king@canonical.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-16 16:45:54 +08:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: Simplify iterator code Remove useless obj variable and goto logic. Signed-off-by: Thomas Graf <tgraf@suug.ch> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-05 02:22:53 +02:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: fix for resize events during table walk If rhashtable_walk_next detects a resize operation in progress, it jumps to the new table and continues walking that one. But it misses to drop the reference to it's current item, leading it to continue traversing the new table's bucket in which the current item is sorted into, and after reaching that bucket's end continues traversing the new table's second bucket instead of the first one, thereby potentially missing items. This fixes the rhashtable runtime test for me. Bug probably introduced by Herbert Xu's patch eddee5ba ("rhashtable: Fix walker behaviour during rehash") although not explicitly tested. Fixes: eddee5ba ("rhashtable: Fix walker behaviour during rehash") Signed-off-by: Phil Sutter <phil@nwl.cc> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-07-06 15:51:20 +02:00
rhashtable: Add barrier to ensure we see new tables in walker The walker is a lockless reader so it too needs an smp_rmb before reading the future_tbl field in order to see any new tables that may contain elements that we should have walked over. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:19 +11:00
rhashtable: Move future_tbl into struct bucket_table This patch moves future_tbl to open up the possibility of having multiple rehashes on the same table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:25 +11:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Simplify iterator code Remove useless obj variable and goto logic. Signed-off-by: Thomas Graf <tgraf@suug.ch> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-05 02:22:53 +02:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: Annotate RCU locking of walkers Fixes the following sparse warnings: lib/rhashtable.c:767:5: warning: context imbalance in 'rhashtable_walk_start' - wrong count at exit lib/rhashtable.c:849:6: warning: context imbalance in 'rhashtable_walk_stop' - unexpected unlock Fixes: f2dba9c6ff0d ("rhashtable: Introduce rhashtable_walk_*") Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-16 10:42:27 +01:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Fix use-after-free in rhashtable_walk_stop The commit c4db8848af6af92f90462258603be844baeab44d ("rhashtable: Move future_tbl into struct bucket_table") introduced a use-after- free bug in rhashtable_walk_stop because it dereferences tbl after droping the RCU read lock. This patch fixes it by moving the RCU read unlock down to the bottom of rhashtable_walk_stop. In fact this was how I had it originally but it got dropped while rearranging patches because this one depended on the async freeing of bucket_table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-15 21:12:04 +11:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Fix sleeping inside RCU critical section in walk_stop The commit 963ecbd41a1026d99ec7537c050867428c397b89 ("rhashtable: Fix use-after-free in rhashtable_walk_stop") fixed a real bug but created another one because we may end up sleeping inside an RCU critical section. This patch fixes it properly by replacing the mutex with a spin lock that specifically protects the walker lists. Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 09:53:17 +11:00
rhashtable: Move future_tbl into struct bucket_table This patch moves future_tbl to open up the possibility of having multiple rehashes on the same table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:25 +11:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Fix sleeping inside RCU critical section in walk_stop The commit 963ecbd41a1026d99ec7537c050867428c397b89 ("rhashtable: Fix use-after-free in rhashtable_walk_stop") fixed a real bug but created another one because we may end up sleeping inside an RCU critical section. This patch fixes it properly by replacing the mutex with a spin lock that specifically protects the walker lists. Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 09:53:17 +11:00
rhashtable: Fix walker behaviour during rehash Previously whenever the walker encountered a resize it simply snaps back to the beginning and starts again. However, this only works if the rehash started and completed while the walker was idle. If the walker attempts to restart while the rehash is still ongoing, we may miss objects that we shouldn't have. This patch fixes this by making the walker walk the old table followed by the new table just like all other readers. If a rehash is detected we will still signal our caller of the fact so they can prepare for duplicates but we will simply continue the walk onto the new table after the old one is finished either by us or by the rehasher. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-14 13:57:20 +11:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: Fix use-after-free in rhashtable_walk_stop The commit c4db8848af6af92f90462258603be844baeab44d ("rhashtable: Move future_tbl into struct bucket_table") introduced a use-after- free bug in rhashtable_walk_stop because it dereferences tbl after droping the RCU read lock. This patch fixes it by moving the RCU read unlock down to the bottom of rhashtable_walk_stop. In fact this was how I had it originally but it got dropped while rearranging patches because this one depended on the async freeing of bucket_table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-15 21:12:04 +11:00
rhashtable: Introduce rhashtable_walk_* Some existing rhashtable users get too intimate with it by walking the buckets directly. This prevents us from easily changing the internals of rhashtable. This patch adds the helpers rhashtable_walk_init/exit/start/next/stop which will replace these custom walkers. They are meant to be usable for both procfs seq_file walks as well as walking by a netlink dump. The iterator structure should fit inside a netlink dump cb structure, with at least one element to spare. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-04 07:33:23 +11:00
rhashtable: Make rhashtable_init params argument const This patch marks the rhashtable_init params argument const as there is no reason to modify it since we will always make a copy of it in the rhashtable. This patch also fixes a bug where we don't actually round up the value of min_size unless it is less than HASH_MIN_SIZE. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:56:59 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
lib/rhashtable: allow user to set the minimum shifts of shrinking Although rhashtable library allows user to specify a quiet big size for user's created hash table, the table may be shrunk to a very small size - HASH_MIN_SIZE(4) after object is removed from the table at the first time. Subsequently, even if the total amount of objects saved in the table is quite lower than user's initial setting in a long time, the hash table size is still dynamically adjusted by rhashtable_shrink() or rhashtable_expand() each time object is inserted or removed from the table. However, as synchronize_rcu() has to be called when table is shrunk or expanded by the two functions, we should permit user to set the minimum table size through configuring the minimum number of shifts according to user specific requirement, avoiding these expensive actions of shrinking or expanding because of calling synchronize_rcu(). Signed-off-by: Ying Xue <ying.xue@windriver.com> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-09-03 09:22:36 +08:00
rhashtable: Remove max_shift and min_shift Now that nobody uses max_shift and min_shift, we can safely remove them. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-18 20:01:21 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Allow hashfn to be unset Since every current rhashtable user uses jhash as their hash function, the fact that jhash is an inline function causes each user to generate a copy of its code. This function provides a solution to this problem by allowing hashfn to be unset. In which case rhashtable will automatically set it to jhash. Furthermore, if the key length is a multiple of 4, we will switch over to jhash2. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:21 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
net: replace remaining users of arch_fast_hash with jhash This patch effectively reverts commit 500f80872645 ("net: ovs: use CRC32 accelerated flow hash if available"), and other remaining arch_fast_hash() users such as from nfsd via commit 6282cd565553 ("NFSD: Don't hand out delegations for 30 seconds after recalling them.") where it has been used as a hash function for bloom filtering. While we think that these users are actually not much of concern, it has been requested to remove the arch_fast_hash() library bits that arose from [1] entirely as per recent discussion [2]. The main argument is that using it as a hash may introduce bias due to its linearity (see avalanche criterion) and thus makes it less clear (though we tried to document that) when this security/performance trade-off is actually acceptable for a general purpose library function. Lets therefore avoid any further confusion on this matter and remove it to prevent any future accidental misuse of it. For the time being, this is going to make hashing of flow keys a bit more expensive in the ovs case, but future work could reevaluate a different hashing discipline. [1] https://patchwork.ozlabs.org/patch/299369/ [2] https://patchwork.ozlabs.org/patch/418756/ Cc: Neil Brown <neilb@suse.de> Cc: Francesco Fusco <fusco@ntop.org> Cc: Jesse Gross <jesse@nicira.com> Cc: Thomas Graf <tgraf@suug.ch> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-10 16:33:11 +01:00
rhashtable: Supports for nulls marker In order to allow for wider usage of rhashtable, use a special nulls marker to terminate each chain. The reason for not using the existing nulls_list is that the prev pointer usage would not be valid as entries can be linked in two different buckets at the same time. The 4 nulls base bits can be set through the rhashtable_params structure like this: struct rhashtable_params params = { [...] .nulls_base = (1U << RHT_BASE_SHIFT), }; This reduces the hash length from 32 bits to 27 bits. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:21 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: provide len to obj_hashfn nftables sets will be converted to use so called setextensions, moving the key to a non-fixed position. To hash it, the obj_hashfn must be used, however it so far doesn't receive the length parameter. Pass the key length to obj_hashfn() and convert existing users. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
2015-03-25 13:07:45 +00:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
net: replace remaining users of arch_fast_hash with jhash This patch effectively reverts commit 500f80872645 ("net: ovs: use CRC32 accelerated flow hash if available"), and other remaining arch_fast_hash() users such as from nfsd via commit 6282cd565553 ("NFSD: Don't hand out delegations for 30 seconds after recalling them.") where it has been used as a hash function for bloom filtering. While we think that these users are actually not much of concern, it has been requested to remove the arch_fast_hash() library bits that arose from [1] entirely as per recent discussion [2]. The main argument is that using it as a hash may introduce bias due to its linearity (see avalanche criterion) and thus makes it less clear (though we tried to document that) when this security/performance trade-off is actually acceptable for a general purpose library function. Lets therefore avoid any further confusion on this matter and remove it to prevent any future accidental misuse of it. For the time being, this is going to make hashing of flow keys a bit more expensive in the ovs case, but future work could reevaluate a different hashing discipline. [1] https://patchwork.ozlabs.org/patch/299369/ [2] https://patchwork.ozlabs.org/patch/418756/ Cc: Neil Brown <neilb@suse.de> Cc: Francesco Fusco <fusco@ntop.org> Cc: Jesse Gross <jesse@nicira.com> Cc: Thomas Graf <tgraf@suug.ch> Signed-off-by: Daniel Borkmann <dborkman@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-12-10 16:33:11 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Make rhashtable_init params argument const This patch marks the rhashtable_init params argument const as there is no reason to modify it since we will always make a copy of it in the rhashtable. This patch also fixes a bug where we don't actually round up the value of min_size unless it is less than HASH_MIN_SIZE. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:56:59 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Allow hashfn to be unset Since every current rhashtable user uses jhash as their hash function, the fact that jhash is an inline function causes each user to generate a copy of its code. This function provides a solution to this problem by allowing hashfn to be unset. In which case rhashtable will automatically set it to jhash. Furthermore, if the key length is a multiple of 4, we will switch over to jhash2. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:21 +11:00
rhashtable: Allow hash/comparison functions to be inlined This patch deals with the complaint that we make indirect function calls on the fast paths unnecessarily in rhashtable. We resolve it by moving the fast paths into inline functions that take struct rhashtable_param (which obviously must be the same set of parameters supplied to rhashtable_init) as an argument. The only remaining indirect call is to obj_hashfn (or key_hashfn it obj_hashfn is unset) on the rehash as well as the insert-during- rehash slow path. This patch also extends the support of vairable-length keys to include those where the key is fixed but scattered in the object. For example, in netlink we want to key off the namespace and the portid but they're not next to each other. This patch does this by directly using the object hash function as the indicator of whether the key is accessible or not. It also adds a new function obj_cmpfn to compare a key against an object. This means that the caller no longer needs to supply explicit compare functions. All this is done in a backwards compatible manner so no existing users are affected until they convert to the new interface. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:57:00 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Supports for nulls marker In order to allow for wider usage of rhashtable, use a special nulls marker to terminate each chain. The reason for not using the existing nulls_list is that the prev pointer usage would not be valid as entries can be linked in two different buckets at the same time. The 4 nulls base bits can be set through the rhashtable_params structure like this: struct rhashtable_params params = { [...] .nulls_base = (1U << RHT_BASE_SHIFT), }; This reduces the hash length from 32 bits to 27 bits. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:21 +01:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Fix sleeping inside RCU critical section in walk_stop The commit 963ecbd41a1026d99ec7537c050867428c397b89 ("rhashtable: Fix use-after-free in rhashtable_walk_stop") fixed a real bug but created another one because we may end up sleeping inside an RCU critical section. This patch fixes it properly by replacing the mutex with a spin lock that specifically protects the walker lists. Reported-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 09:53:17 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Round up/down min/max_size to ensure we respect limit Round up min_size respectively round down max_size to the next power of two to make sure we always respect the limit specified by the user. This is required because we compare the table size against the limit before we expand or shrink. Also fixes a minor bug where we modified min_size in the params provided instead of the copy stored in struct rhashtable. Signed-off-by: Thomas Graf <tgraf@suug.ch> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-19 22:31:13 +00:00
rhashtable: Add cap on number of elements in hash table We currently have no limit on the number of elements in a hash table. This is a problem because some users (tipc) set a ceiling on the maximum table size and when that is reached the hash table may degenerate. Others may encounter OOM when growing and if we allow insertions when that happens the hash table perofrmance may also suffer. This patch adds a new paramater insecure_max_entries which becomes the cap on the table. If unset it defaults to max_size * 2. If it is also zero it means that there is no cap on the number of elements in the table. However, the table will grow whenever the utilisation hits 100% and if that growth fails, you will get ENOMEM on insertion. As allowing oversubscription is potentially dangerous, the name contains the word insecure. Note that the cap is not a hard limit. This is done for performance reasons as enforcing a hard limit will result in use of atomic ops that are heavier than the ones we currently use. The reasoning is that we're only guarding against a gross over- subscription of the table, rather than a small breach of the limit. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-05-15 11:30:47 +08:00
rhashtable: Make rhashtable_init params argument const This patch marks the rhashtable_init params argument const as there is no reason to modify it since we will always make a copy of it in the rhashtable. This patch also fixes a bug where we don't actually round up the value of min_size unless it is less than HASH_MIN_SIZE. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-20 21:56:59 +11:00
rhashtable: Round up/down min/max_size to ensure we respect limit Round up min_size respectively round down max_size to the next power of two to make sure we always respect the limit specified by the user. This is required because we compare the table size against the limit before we expand or shrink. Also fixes a minor bug where we modified min_size in the params provided instead of the copy stored in struct rhashtable. Signed-off-by: Thomas Graf <tgraf@suug.ch> Acked-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-19 22:31:13 +00:00
rhashtable: Enforce minimum size on initial hash table William Hua <william.hua@canonical.com> wrote: > > I wasn't aware there was an enforced minimum size. I simply set the > nelem_hint in the rhastable_params struct to 1, expecting it to grow as > needed. This caused a segfault afterwards when trying to insert an > element. OK we're doing the size computation before we enforce the limit on min_size. ---8<--- We need to do the initial hash table size computation after we have obtained the correct min_size/max_size parameters. Otherwise we may end up with a hash table whose size is outside the allowed envelope. Fixes: a998f712f77e ("rhashtable: Round up/down min/max_size to...") Reported-by: William Hua <william.hua@canonical.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-12-16 18:13:14 +08:00
rhashtable: Add comment on choice of elasticity value This patch adds a comment on the choice of the value 16 as the maximum chain length before we force a rehash. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 13:37:30 +11:00
rhashtable: Add immediate rehash during insertion This patch reintroduces immediate rehash during insertion. If we find during insertion that the table is full or the chain length exceeds a set limit (currently 16 but may be disabled with insecure_elasticity) then we will force an immediate rehash. The rehash will contain an expansion if the table utilisation exceeds 75%. If this rehash fails then the insertion will fail. Otherwise the insertion will be reattempted in the new hash table. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:28 +11:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Allow hashfn to be unset Since every current rhashtable user uses jhash as their hash function, the fact that jhash is an inline function causes each user to generate a copy of its code. This function provides a solution to this problem by allowing hashfn to be unset. In which case rhashtable will automatically set it to jhash. Furthermore, if the key length is a multiple of 4, we will switch over to jhash2. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:21 +11:00
rhashtable: Allow GFP_ATOMIC bucket table allocation This patch adds the ability to allocate bucket table with GFP_ATOMIC instead of GFP_KERNEL. This is needed when we perform an immediate rehash during insertion. Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 00:50:27 +11:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: initialize atomic nelems variable Signed-off-by: Ying Xue <ying.xue@windriver.com> Cc: Thomas Graf <tgraf@suug.ch> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-07 13:41:57 +08:00
rhashtable: kill ht->shift atomic operations Commit c0c09bfdc415 ("rhashtable: avoid unnecessary wakeup for worker queue") changed ht->shift to be atomic, which is actually unnecessary. Instead of leaving the current shift in the core rhashtable structure, it can be cached inside the individual bucket tables. There, it will only be initialized once during a new table allocation in the shrink/expansion slow path, and from then onward it stays immutable for the rest of the bucket table liftime. That allows shift to be non-atomic. The patch also moves hash_rnd management into the table setup. The rhashtable structure now consumes 3 instead of 4 cachelines. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Ying Xue <ying.xue@windriver.com> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-12 15:28:40 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: remove indirection for grow/shrink decision functions Currently, all real users of rhashtable default their grow and shrink decision functions to rht_grow_above_75() and rht_shrink_below_30(), so that there's currently no need to have this explicitly selectable. It can/should be generic and private inside rhashtable until a real use case pops up. Since we can make this private, we'll save us this additional indirection layer and can improve insertion/deletion time as well. Reference: http://patchwork.ozlabs.org/patch/443040/ Suggested-by: David S. Miller <davem@davemloft.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-25 16:31:54 +01:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add rhashtable_free_and_destroy() rhashtable_destroy() variant which stops rehashes, iterates over the table and calls a callback to release resources. Avoids need for nft_hash to embed rhashtable internals and allows to get rid of the being_destroyed flag. It also saves a 2nd mutex lock upon destruction. Also fixes an RCU lockdep splash on nft set destruction due to calling rht_for_each_entry_safe() without holding bucket locks. Open code this loop as we need know that no mutations may occur in parallel. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add rhashtable_free_and_destroy() rhashtable_destroy() variant which stops rehashes, iterates over the table and calls a callback to release resources. Avoids need for nft_hash to embed rhashtable internals and allows to get rid of the being_destroyed flag. It also saves a 2nd mutex lock upon destruction. Also fixes an RCU lockdep splash on nft set destruction due to calling rht_for_each_entry_safe() without holding bucket locks. Open code this loop as we need know that no mutations may occur in parallel. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add rhashtable_free_and_destroy() rhashtable_destroy() variant which stops rehashes, iterates over the table and calls a callback to release resources. Avoids need for nft_hash to embed rhashtable internals and allows to get rid of the being_destroyed flag. It also saves a 2nd mutex lock upon destruction. Also fixes an RCU lockdep splash on nft set destruction due to calling rht_for_each_entry_safe() without holding bucket locks. Open code this loop as we need know that no mutations may occur in parallel. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add rhashtable_free_and_destroy() rhashtable_destroy() variant which stops rehashes, iterates over the table and calls a callback to release resources. Avoids need for nft_hash to embed rhashtable internals and allows to get rid of the being_destroyed flag. It also saves a 2nd mutex lock upon destruction. Also fixes an RCU lockdep splash on nft set destruction due to calling rht_for_each_entry_safe() without holding bucket locks. Open code this loop as we need know that no mutations may occur in parallel. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add rhashtable_free_and_destroy() rhashtable_destroy() variant which stops rehashes, iterates over the table and calls a callback to release resources. Avoids need for nft_hash to embed rhashtable internals and allows to get rid of the being_destroyed flag. It also saves a 2nd mutex lock upon destruction. Also fixes an RCU lockdep splash on nft set destruction due to calling rht_for_each_entry_safe() without holding bucket locks. Open code this loop as we need know that no mutations may occur in parallel. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:20 +01:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: remove indirection for grow/shrink decision functions Currently, all real users of rhashtable default their grow and shrink decision functions to rht_grow_above_75() and rht_shrink_below_30(), so that there's currently no need to have this explicitly selectable. It can/should be generic and private inside rhashtable until a real use case pops up. Since we can make this private, we'll save us this additional indirection layer and can improve insertion/deletion time as well. Reference: http://patchwork.ozlabs.org/patch/443040/ Suggested-by: David S. Miller <davem@davemloft.net> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-02-25 16:31:54 +01:00
rhashtable: Fix race in rhashtable_destroy() and use regular work_struct When we put our declared work task in the global workqueue with schedule_delayed_work(), its delay parameter is always zero. Therefore, we should define a regular work in rhashtable structure instead of a delayed work. By the way, we add a condition to check whether resizing functions are NULL before cancelling the work, avoiding to cancel an uninitialized work. Lastly, while we wait for all work items we submitted before to run to completion with cancel_delayed_work(), ht->mutex has been taken in rhashtable_destroy(). Moreover, cancel_delayed_work() doesn't return until all work items are accomplished, and when work items are scheduled, the work's function - rht_deferred_worker() will be called. However, as rht_deferred_worker() also needs to acquire the lock, deadlock might happen at the moment as the lock is already held before. So if the cancel work function is moved out of the lock covered scope, this will avoid the deadlock. Fixes: 97defe1 ("rhashtable: Per bucket locks & deferred expansion/shrinking") Signed-off-by: Ying Xue <ying.xue@windriver.com> Cc: Thomas Graf <tgraf@suug.ch> Acked-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-16 11:13:09 +08:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
rhashtable: Add rhashtable_free_and_destroy() rhashtable_destroy() variant which stops rehashes, iterates over the table and calls a callback to release resources. Avoids need for nft_hash to embed rhashtable internals and allows to get rid of the being_destroyed flag. It also saves a 2nd mutex lock upon destruction. Also fixes an RCU lockdep splash on nft set destruction due to calling rht_for_each_entry_safe() without holding bucket locks. Open code this loop as we need know that no mutations may occur in parallel. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:20 +01:00
rhashtable: Per bucket locks & deferred expansion/shrinking Introduces an array of spinlocks to protect bucket mutations. The number of spinlocks per CPU is configurable and selected based on the hash of the bucket. This allows for parallel insertions and removals of entries which do not share a lock. The patch also defers expansion and shrinking to a worker queue which allows insertion and removal from atomic context. Insertions and deletions may occur in parallel to it and are only held up briefly while the particular bucket is linked or unzipped. Mutations of the bucket table pointer is protected by a new mutex, read access is RCU protected. In the event of an expansion or shrinking, the new bucket table allocated is exposed as a so called future table as soon as the resize process starts. Lookups, deletions, and insertions will briefly use both tables. The future table becomes the main table after an RCU grace period and initial linking of the old to the new table was performed. Optimization of the chains to make use of the new number of buckets follows only the new table is in use. The side effect of this is that during that RCU grace period, a bucket traversal using any rht_for_each() variant on the main table will not see any insertions performed during the RCU grace period which would at that point land in the future table. The lookup will see them as it searches both tables if needed. Having multiple insertions and removals occur in parallel requires nelems to become an atomic counter. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-01-02 23:00:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00
rhashtable: Add rhashtable_free_and_destroy() rhashtable_destroy() variant which stops rehashes, iterates over the table and calls a callback to release resources. Avoids need for nft_hash to embed rhashtable internals and allows to get rid of the being_destroyed flag. It also saves a 2nd mutex lock upon destruction. Also fixes an RCU lockdep splash on nft set destruction due to calling rht_for_each_entry_safe() without holding bucket locks. Open code this loop as we need know that no mutations may occur in parallel. Signed-off-by: Thomas Graf <tgraf@suug.ch> Signed-off-by: David S. Miller <davem@davemloft.net>
2015-03-24 14:18:20 +01:00
lib: Resizable, Scalable, Concurrent Hash Table Generic implementation of a resizable, scalable, concurrent hash table based on [0]. The implementation supports both, fixed size keys specified via an offset and length, or arbitrary keys via own hash and compare functions. Lookups are lockless and protected as RCU read side critical sections. Automatic growing/shrinking based on user configurable watermarks is available while allowing concurrent lookups to take place. Objects to be hashed must include a struct rhash_head. The reason for not using the existing struct hlist_head is that the expansion and shrinking will have two buckets point to a single entry which would lead in obscure reverse chaining behaviour. Code includes a boot selftest if CONFIG_TEST_RHASHTABLE is defined. [0] https://www.usenix.org/legacy/event/atc11/tech/final_files/Triplett.pdf Signed-off-by: Thomas Graf <tgraf@suug.ch> Reviewed-by: Nikolay Aleksandrov <nikolay@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-08-02 11:47:44 +02:00