kernel/linux
0
Fork 0
mirror of https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ synced 2026-10-18 19:12:56 +00:00
Code Issues Releases Packages Activity
linux/net/core/utils.c

389 lines
8.8 KiB
Raw Normal View History

Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
[NET]: is it Andy or Andi ?? I don't know of any Andy Kleen's but I do know a Andi Kleen. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-09-27 22:55:39 -07:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
net: core: let's use native isxdigit instead of custom In kernel we have fast and pretty implementation of the isxdigit() function. Let's use it. Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-03-27 05:54:13 +00:00
[NET]: Fix sparse warnings Of this type, mostly: CHECK net/ipv6/netfilter.c net/ipv6/netfilter.c:96:12: warning: symbol 'ipv6_netfilter_init' was not declared. Should it be static? net/ipv6/netfilter.c:101:6: warning: symbol 'ipv6_netfilter_fini' was not declared. Should it be static? Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-16 02:18:02 -03:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
[NET]: Fix sparse warnings Of this type, mostly: CHECK net/ipv6/netfilter.c net/ipv6/netfilter.c:96:12: warning: symbol 'ipv6_netfilter_init' was not declared. Should it be static? net/ipv6/netfilter.c:101:6: warning: symbol 'ipv6_netfilter_fini' was not declared. Should it be static? Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-08-16 02:18:02 -03:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
printk: Remove ratelimit.h from kernel.h Decouple kernel.h from ratelimit.h: the global declaration of printk's ratelimit_state is not needed, and it leads to messy circular dependencies due to ratelimit.h's (new) adding of a spinlock_types.h include. Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: David S. Miller <davem@davemloft.net> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-09-22 16:18:09 +02:00
[NET] net/core/utils: fix sparse warning net_msg_warn is not defined because it is in net/sock.h which isn't included. Signed-off-by: Johannes Berg <johannes@sipsolutions.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-08-07 18:02:43 -07:00
net: Kill ratelimit.h dependency in linux/net.h Ingo Molnar noticed that we have this unnecessary ratelimit.h dependency in linux/net.h, which hid compilation problems from people doing builds only with CONFIG_NET enabled. Move this stuff out to a seperate net/net_ratelimit.h file and include that in the only two places where this thing is needed. Signed-off-by: David S. Miller <davem@davemloft.net> Acked-by: Ingo Molnar <mingo@elte.hu>
2011-05-27 13:41:33 -04:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
[NET]: Move in_aton from net/ipv4/utils.c to net/core/utils.c Move in_aton to allow netpoll and pktgen to work without the rest of the IPv4 stack. Fix whitespace and add comment for the odd placement. Delete now-empty net/ipv4/utils.c Re-enable netpoll/netconsole without CONFIG_INET Signed-off-by: Matt Mackall <mpm@selenic.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-27 15:24:42 -07:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
[NET]: New sysctls should use __read_mostly tags net_msg_warn should be placed in the read_mostly section, to avoid performance problems on SMP Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-03-08 22:36:37 -08:00
[NET]: Replace CONFIG_NET_DEBUG with sysctl. Covert network warning messages from a compile time to runtime choice. Removes kernel config option and replaces it with new /proc/sys/net/core/warnings. Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-03-08 20:41:08 -08:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
printk ratelimiting rewrite All ratelimit user use same jiffies and burst params, so some messages (callbacks) will be lost. For example: a call printk_ratelimit(5 * HZ, 1) b call printk_ratelimit(5 * HZ, 1) before the 5*HZ timeout of a, then b will will be supressed. - rewrite __ratelimit, and use a ratelimit_state as parameter. Thanks for hints from andrew. - Add WARN_ON_RATELIMIT, update rcupreempt.h - remove __printk_ratelimit - use __ratelimit in net_ratelimit Signed-off-by: Dave Young <hidave.darkstar@gmail.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Dave Young <hidave.darkstar@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 01:45:58 -07:00
[NET] CORE: Fix whitespace errors. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-02-09 23:24:36 +09:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
[NET] CORE: Fix whitespace errors. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-02-09 23:24:36 +09:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
printk ratelimiting rewrite All ratelimit user use same jiffies and burst params, so some messages (callbacks) will be lost. For example: a call printk_ratelimit(5 * HZ, 1) b call printk_ratelimit(5 * HZ, 1) before the 5*HZ timeout of a, then b will will be supressed. - rewrite __ratelimit, and use a ratelimit_state as parameter. Thanks for hints from andrew. - Add WARN_ON_RATELIMIT, update rcupreempt.h - remove __printk_ratelimit - use __ratelimit in net_ratelimit Signed-off-by: Dave Young <hidave.darkstar@gmail.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Cc: Dave Young <hidave.darkstar@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-25 01:45:58 -07:00
Linux-2.6.12-rc2 Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
2005-04-16 15:20:36 -07:00
[NET]: Move in_aton from net/ipv4/utils.c to net/core/utils.c Move in_aton to allow netpoll and pktgen to work without the rest of the IPv4 stack. Fix whitespace and add comment for the odd placement. Delete now-empty net/ipv4/utils.c Re-enable netpoll/netconsole without CONFIG_INET Signed-off-by: Matt Mackall <mpm@selenic.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-27 15:24:42 -07:00
[NET]: Endian-annotate in_aton() Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-01-06 13:24:54 -08:00
[NET]: Move in_aton from net/ipv4/utils.c to net/core/utils.c Move in_aton to allow netpoll and pktgen to work without the rest of the IPv4 stack. Fix whitespace and add comment for the odd placement. Delete now-empty net/ipv4/utils.c Re-enable netpoll/netconsole without CONFIG_INET Signed-off-by: Matt Mackall <mpm@selenic.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-27 15:24:42 -07:00
net: Fixed coding style issues relating to braces. Fixed coding style issues in net/core/utils.c in relation with braces placement. Signed-off-by: Jeffrin Jose <ahiliation@yahoo.co.in> Signed-off-by: David S. Miller <davem@davemloft.net>
2012-04-08 06:07:42 +00:00
[NET]: Move in_aton from net/ipv4/utils.c to net/core/utils.c Move in_aton to allow netpoll and pktgen to work without the rest of the IPv4 stack. Fix whitespace and add comment for the odd placement. Delete now-empty net/ipv4/utils.c Re-enable netpoll/netconsole without CONFIG_INET Signed-off-by: Matt Mackall <mpm@selenic.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-27 15:24:42 -07:00
net: Fixed coding style issues relating to braces. Fixed coding style issues in net/core/utils.c in relation with braces placement. Signed-off-by: Jeffrin Jose <ahiliation@yahoo.co.in> Signed-off-by: David S. Miller <davem@davemloft.net>
2012-04-08 06:07:42 +00:00
[NET]: Move in_aton from net/ipv4/utils.c to net/core/utils.c Move in_aton to allow netpoll and pktgen to work without the rest of the IPv4 stack. Fix whitespace and add comment for the odd placement. Delete now-empty net/ipv4/utils.c Re-enable netpoll/netconsole without CONFIG_INET Signed-off-by: Matt Mackall <mpm@selenic.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-27 15:24:42 -07:00
net: Fixed coding style issues relating to braces. Fixed coding style issues in net/core/utils.c in relation with braces placement. Signed-off-by: Jeffrin Jose <ahiliation@yahoo.co.in> Signed-off-by: David S. Miller <davem@davemloft.net>
2012-04-08 06:07:42 +00:00
[NET]: Move in_aton from net/ipv4/utils.c to net/core/utils.c Move in_aton to allow netpoll and pktgen to work without the rest of the IPv4 stack. Fix whitespace and add comment for the odd placement. Delete now-empty net/ipv4/utils.c Re-enable netpoll/netconsole without CONFIG_INET Signed-off-by: Matt Mackall <mpm@selenic.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-27 15:24:42 -07:00
net: return operator cleanup Change "return (EXPR);" to "return EXPR;" return is not a function, parentheses are not required. Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2010-09-22 20:43:57 +00:00
[NET]: Move in_aton from net/ipv4/utils.c to net/core/utils.c Move in_aton to allow netpoll and pktgen to work without the rest of the IPv4 stack. Fix whitespace and add comment for the odd placement. Delete now-empty net/ipv4/utils.c Re-enable netpoll/netconsole without CONFIG_INET Signed-off-by: Matt Mackall <mpm@selenic.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2005-07-27 15:24:42 -07:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
[NET]: Accept wildcard delimiters in in[46]_pton Accept -1 as delimiter to abort parsing without an error at the first unknown character. This is needed by the upcoming nf_conntrack SIP helper, where addresses are delimited by either '\r' or '\n' characters. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02 22:04:04 -08:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
net: core: use kernel's converter from hex to bin Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2010-09-20 20:40:26 +00:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
net: core: use kernel's converter from hex to bin Signed-off-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2010-09-20 20:40:26 +00:00
[NET]: Accept wildcard delimiters in in[46]_pton Accept -1 as delimiter to abort parsing without an error at the first unknown character. This is needed by the upcoming nf_conntrack SIP helper, where addresses are delimited by either '\r' or '\n' characters. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02 22:04:04 -08:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
net: add doc for in4_pton() It is not easy to use in4_pton() correctly without reading its definition, so add some doc for it. Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Cong Wang <amwang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2012-10-11 21:06:17 +00:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
[NET]: Accept wildcard delimiters in in[46]_pton Accept -1 as delimiter to abort parsing without an error at the first unknown character. This is needed by the upcoming nf_conntrack SIP helper, where addresses are delimited by either '\r' or '\n' characters. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02 22:04:04 -08:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
[NET]: parse ip:port strings correctly in in4_pton in4_pton converts a textual representation of an ip4 address into an integer representation. However, when the textual representation is of in the form ip:port, e.g. 192.168.1.1:5060, and 'delim' is set to -1, the function bails out with an error when reading the colon. It makes sense to allow the colon as a delimiting character without explicitly having to set it through the 'delim' variable as there can be no ambiguity in the point where the ip address is completely parsed. This function is indeed called from nf_conntrack_sip.c in this way to parse textual ip:port combinations which fails due to the reason stated above. Signed-off-by: Jerome Borsboom <j.borsboom@erasmusmc.nl> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-05-29 12:59:54 -07:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
[NET]: parse ip:port strings correctly in in4_pton in4_pton converts a textual representation of an ip4 address into an integer representation. However, when the textual representation is of in the form ip:port, e.g. 192.168.1.1:5060, and 'delim' is set to -1, the function bails out with an error when reading the colon. It makes sense to allow the colon as a delimiting character without explicitly having to set it through the 'delim' variable as there can be no ambiguity in the point where the ip address is completely parsed. This function is indeed called from nf_conntrack_sip.c in this way to parse textual ip:port combinations which fails due to the reason stated above. Signed-off-by: Jerome Borsboom <j.borsboom@erasmusmc.nl> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-05-29 12:59:54 -07:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
[NET]: parse ip:port strings correctly in in4_pton in4_pton converts a textual representation of an ip4 address into an integer representation. However, when the textual representation is of in the form ip:port, e.g. 192.168.1.1:5060, and 'delim' is set to -1, the function bails out with an error when reading the colon. It makes sense to allow the colon as a delimiting character without explicitly having to set it through the 'delim' variable as there can be no ambiguity in the point where the ip address is completely parsed. This function is indeed called from nf_conntrack_sip.c in this way to parse textual ip:port combinations which fails due to the reason stated above. Signed-off-by: Jerome Borsboom <j.borsboom@erasmusmc.nl> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-05-29 12:59:54 -07:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
net: add doc for in6_pton() It is not easy to use in6_pton() correctly without reading its definition, so add some doc for it. Cc: David S. Miller <davem@davemloft.net> Signed-off-by: Cong Wang <amwang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2012-10-11 21:06:16 +00:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
[NET]: Accept wildcard delimiters in in[46]_pton Accept -1 as delimiter to abort parsing without an error at the first unknown character. This is needed by the upcoming nf_conntrack SIP helper, where addresses are delimited by either '\r' or '\n' characters. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
2006-12-02 22:04:04 -08:00
[NET]: Add common helper functions to convert IPv6/IPv4 address string to network address structure. These helpers can be used in netfilter, cifs etc. Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
2006-06-25 23:54:55 +09:00
[NET]: Move netfilter checksum helpers to net/core/utils.c This allows to get rid of the CONFIG_NETFILTER dependency of NET_ACT_NAT. This patch redefines the old names to keep the noise low, the next patch converts all users. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au> Signed-off-by: David S. Miller <davem@davemloft.net>
2007-11-30 01:14:30 +11:00
net: add mac_pton() for parsing MAC address mac_pton() parses MAC address in form XX:XX:XX:XX:XX:XX and only in that form. mac_pton() doesn't dirty result until it's sure string representation is valid. mac_pton() doesn't care about characters _after_ last octet, it's up to caller to deal with it. mac_pton() diverges from 0/-E return value convention. Target usage: if (!mac_pton(str, whatever->mac)) return -EINVAL; /* ->mac being u8 [ETH_ALEN] is filled at this point. */ /* optionally check str[3 * ETH_ALEN - 1] for termination */ Use mac_pton() in pktgen and netconsole for start. Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
2011-05-07 23:00:07 +00:00
net: core: add function for incremental IPv6 pseudo header checksum updates Add inet_proto_csum_replace16 for incrementally updating IPv6 pseudo header checksums for IPv6 NAT. Signed-off-by: Patrick McHardy <kaber@trash.net> Acked-by: David S. Miller <davem@davemloft.net>
2012-08-26 19:14:10 +02:00
net: introduce new macro net_get_random_once net_get_random_once is a new macro which handles the initialization of secret keys. It is possible to call it in the fast path. Only the initialization depends on the spinlock and is rather slow. Otherwise it should get used just before the key is used to delay the entropy extration as late as possible to get better randomness. It returns true if the key got initialized. The usage of static_keys for net_get_random_once is a bit uncommon so it needs some further explanation why this actually works: === In the simple non-HAVE_JUMP_LABEL case we actually have === no constrains to use static_key_(true|false) on keys initialized with STATIC_KEY_INIT_(FALSE|TRUE). So this path just expands in favor of the likely case that the initialization is already done. The key is initialized like this: ___done_key = { .enabled = ATOMIC_INIT(0) } The check if (!static_key_true(&___done_key)) \ expands into (pseudo code) if (!likely(___done_key > 0)) , so we take the fast path as soon as ___done_key is increased from the helper function. === If HAVE_JUMP_LABELs are available this depends === on patching of jumps into the prepared NOPs, which is done in jump_label_init at boot-up time (from start_kernel). It is forbidden and dangerous to use net_get_random_once in functions which are called before that! At compilation time NOPs are generated at the call sites of net_get_random_once. E.g. net/ipv6/inet6_hashtable.c:inet6_ehashfn (we need to call net_get_random_once two times in inet6_ehashfn, so two NOPs): 71: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 76: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) Both will be patched to the actual jumps to the end of the function to call __net_get_random_once at boot time as explained above. arch_static_branch is optimized and inlined for false as return value and actually also returns false in case the NOP is placed in the instruction stream. So in the fast case we get a "return false". But because we initialize ___done_key with (enabled != (entries & 1)) this call-site will get patched up at boot thus returning true. The final check looks like this: if (!static_key_true(&___done_key)) \ ___ret = __net_get_random_once(buf, \ expands to if (!!static_key_false(&___done_key)) \ ___ret = __net_get_random_once(buf, \ So we get true at boot time and as soon as static_key_slow_inc is called on the key it will invert the logic and return false for the fast path. static_key_slow_inc will change the branch because it got initialized with .enabled == 0. After static_key_slow_inc is called on the key the branch is replaced with a nop again. === Misc: === The helper defers the increment into a workqueue so we don't have problems calling this code from atomic sections. A seperate boolean (___done) guards the case where we enter net_get_random_once again before the increment happend. Cc: Ingo Molnar <mingo@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19 21:48:55 +02:00
net: avoid dependency of net_get_random_once on nop patching net_get_random_once depends on the static keys infrastructure to patch up the branch to the slow path during boot. This was realized by abusing the static keys api and defining a new initializer to not enable the call site while still indicating that the branch point should get patched up. This was needed to have the fast path considered likely by gcc. The static key initialization during boot up normally walks through all the registered keys and either patches in ideal nops or enables the jump site but omitted that step on x86 if ideal nops where already placed at static_key branch points. Thus net_get_random_once branches not always became active. This patch switches net_get_random_once to the ordinary static_key api and thus places the kernel fast path in the - by gcc considered - unlikely path. Microbenchmarks on Intel and AMD x86-64 showed that the unlikely path actually beats the likely path in terms of cycle cost and that different nop patterns did not make much difference, thus this switch should not be noticeable. Fixes: a48e42920ff38b ("net: introduce new macro net_get_random_once") Reported-by: Tuomas Räsänen <tuomasjjrasanen@tjjr.fi> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-05-11 22:59:30 +02:00
net: introduce new macro net_get_random_once net_get_random_once is a new macro which handles the initialization of secret keys. It is possible to call it in the fast path. Only the initialization depends on the spinlock and is rather slow. Otherwise it should get used just before the key is used to delay the entropy extration as late as possible to get better randomness. It returns true if the key got initialized. The usage of static_keys for net_get_random_once is a bit uncommon so it needs some further explanation why this actually works: === In the simple non-HAVE_JUMP_LABEL case we actually have === no constrains to use static_key_(true|false) on keys initialized with STATIC_KEY_INIT_(FALSE|TRUE). So this path just expands in favor of the likely case that the initialization is already done. The key is initialized like this: ___done_key = { .enabled = ATOMIC_INIT(0) } The check if (!static_key_true(&___done_key)) \ expands into (pseudo code) if (!likely(___done_key > 0)) , so we take the fast path as soon as ___done_key is increased from the helper function. === If HAVE_JUMP_LABELs are available this depends === on patching of jumps into the prepared NOPs, which is done in jump_label_init at boot-up time (from start_kernel). It is forbidden and dangerous to use net_get_random_once in functions which are called before that! At compilation time NOPs are generated at the call sites of net_get_random_once. E.g. net/ipv6/inet6_hashtable.c:inet6_ehashfn (we need to call net_get_random_once two times in inet6_ehashfn, so two NOPs): 71: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 76: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) Both will be patched to the actual jumps to the end of the function to call __net_get_random_once at boot time as explained above. arch_static_branch is optimized and inlined for false as return value and actually also returns false in case the NOP is placed in the instruction stream. So in the fast case we get a "return false". But because we initialize ___done_key with (enabled != (entries & 1)) this call-site will get patched up at boot thus returning true. The final check looks like this: if (!static_key_true(&___done_key)) \ ___ret = __net_get_random_once(buf, \ expands to if (!!static_key_false(&___done_key)) \ ___ret = __net_get_random_once(buf, \ So we get true at boot time and as soon as static_key_slow_inc is called on the key it will invert the logic and return false for the fast path. static_key_slow_inc will change the branch because it got initialized with .enabled == 0. After static_key_slow_inc is called on the key the branch is replaced with a nop again. === Misc: === The helper defers the increment into a workqueue so we don't have problems calling this code from atomic sections. A seperate boolean (___done) guards the case where we enter net_get_random_once again before the increment happend. Cc: Ingo Molnar <mingo@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19 21:48:55 +02:00
net: avoid dependency of net_get_random_once on nop patching net_get_random_once depends on the static keys infrastructure to patch up the branch to the slow path during boot. This was realized by abusing the static keys api and defining a new initializer to not enable the call site while still indicating that the branch point should get patched up. This was needed to have the fast path considered likely by gcc. The static key initialization during boot up normally walks through all the registered keys and either patches in ideal nops or enables the jump site but omitted that step on x86 if ideal nops where already placed at static_key branch points. Thus net_get_random_once branches not always became active. This patch switches net_get_random_once to the ordinary static_key api and thus places the kernel fast path in the - by gcc considered - unlikely path. Microbenchmarks on Intel and AMD x86-64 showed that the unlikely path actually beats the likely path in terms of cycle cost and that different nop patterns did not make much difference, thus this switch should not be noticeable. Fixes: a48e42920ff38b ("net: introduce new macro net_get_random_once") Reported-by: Tuomas Räsänen <tuomasjjrasanen@tjjr.fi> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-05-11 22:59:30 +02:00
net: introduce new macro net_get_random_once net_get_random_once is a new macro which handles the initialization of secret keys. It is possible to call it in the fast path. Only the initialization depends on the spinlock and is rather slow. Otherwise it should get used just before the key is used to delay the entropy extration as late as possible to get better randomness. It returns true if the key got initialized. The usage of static_keys for net_get_random_once is a bit uncommon so it needs some further explanation why this actually works: === In the simple non-HAVE_JUMP_LABEL case we actually have === no constrains to use static_key_(true|false) on keys initialized with STATIC_KEY_INIT_(FALSE|TRUE). So this path just expands in favor of the likely case that the initialization is already done. The key is initialized like this: ___done_key = { .enabled = ATOMIC_INIT(0) } The check if (!static_key_true(&___done_key)) \ expands into (pseudo code) if (!likely(___done_key > 0)) , so we take the fast path as soon as ___done_key is increased from the helper function. === If HAVE_JUMP_LABELs are available this depends === on patching of jumps into the prepared NOPs, which is done in jump_label_init at boot-up time (from start_kernel). It is forbidden and dangerous to use net_get_random_once in functions which are called before that! At compilation time NOPs are generated at the call sites of net_get_random_once. E.g. net/ipv6/inet6_hashtable.c:inet6_ehashfn (we need to call net_get_random_once two times in inet6_ehashfn, so two NOPs): 71: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 76: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) Both will be patched to the actual jumps to the end of the function to call __net_get_random_once at boot time as explained above. arch_static_branch is optimized and inlined for false as return value and actually also returns false in case the NOP is placed in the instruction stream. So in the fast case we get a "return false". But because we initialize ___done_key with (enabled != (entries & 1)) this call-site will get patched up at boot thus returning true. The final check looks like this: if (!static_key_true(&___done_key)) \ ___ret = __net_get_random_once(buf, \ expands to if (!!static_key_false(&___done_key)) \ ___ret = __net_get_random_once(buf, \ So we get true at boot time and as soon as static_key_slow_inc is called on the key it will invert the logic and return false for the fast path. static_key_slow_inc will change the branch because it got initialized with .enabled == 0. After static_key_slow_inc is called on the key the branch is replaced with a nop again. === Misc: === The helper defers the increment into a workqueue so we don't have problems calling this code from atomic sections. A seperate boolean (___done) guards the case where we enter net_get_random_once again before the increment happend. Cc: Ingo Molnar <mingo@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19 21:48:55 +02:00
net: make net_get_random_once irq safe I initial build non irq safe version of net_get_random_once because I would liked to have the freedom to defer even the extraction process of get_random_bytes until the nonblocking pool is fully seeded. I don't think this is a good idea anymore and thus this patch makes net_get_random_once irq safe. Now someone using net_get_random_once does not need to care from where it is called. Cc: David S. Miller <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-23 20:05:27 +02:00
net: introduce new macro net_get_random_once net_get_random_once is a new macro which handles the initialization of secret keys. It is possible to call it in the fast path. Only the initialization depends on the spinlock and is rather slow. Otherwise it should get used just before the key is used to delay the entropy extration as late as possible to get better randomness. It returns true if the key got initialized. The usage of static_keys for net_get_random_once is a bit uncommon so it needs some further explanation why this actually works: === In the simple non-HAVE_JUMP_LABEL case we actually have === no constrains to use static_key_(true|false) on keys initialized with STATIC_KEY_INIT_(FALSE|TRUE). So this path just expands in favor of the likely case that the initialization is already done. The key is initialized like this: ___done_key = { .enabled = ATOMIC_INIT(0) } The check if (!static_key_true(&___done_key)) \ expands into (pseudo code) if (!likely(___done_key > 0)) , so we take the fast path as soon as ___done_key is increased from the helper function. === If HAVE_JUMP_LABELs are available this depends === on patching of jumps into the prepared NOPs, which is done in jump_label_init at boot-up time (from start_kernel). It is forbidden and dangerous to use net_get_random_once in functions which are called before that! At compilation time NOPs are generated at the call sites of net_get_random_once. E.g. net/ipv6/inet6_hashtable.c:inet6_ehashfn (we need to call net_get_random_once two times in inet6_ehashfn, so two NOPs): 71: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 76: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) Both will be patched to the actual jumps to the end of the function to call __net_get_random_once at boot time as explained above. arch_static_branch is optimized and inlined for false as return value and actually also returns false in case the NOP is placed in the instruction stream. So in the fast case we get a "return false". But because we initialize ___done_key with (enabled != (entries & 1)) this call-site will get patched up at boot thus returning true. The final check looks like this: if (!static_key_true(&___done_key)) \ ___ret = __net_get_random_once(buf, \ expands to if (!!static_key_false(&___done_key)) \ ___ret = __net_get_random_once(buf, \ So we get true at boot time and as soon as static_key_slow_inc is called on the key it will invert the logic and return false for the fast path. static_key_slow_inc will change the branch because it got initialized with .enabled == 0. After static_key_slow_inc is called on the key the branch is replaced with a nop again. === Misc: === The helper defers the increment into a workqueue so we don't have problems calling this code from atomic sections. A seperate boolean (___done) guards the case where we enter net_get_random_once again before the increment happend. Cc: Ingo Molnar <mingo@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19 21:48:55 +02:00
net: make net_get_random_once irq safe I initial build non irq safe version of net_get_random_once because I would liked to have the freedom to defer even the extraction process of get_random_bytes until the nonblocking pool is fully seeded. I don't think this is a good idea anymore and thus this patch makes net_get_random_once irq safe. Now someone using net_get_random_once does not need to care from where it is called. Cc: David S. Miller <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-23 20:05:27 +02:00
net: introduce new macro net_get_random_once net_get_random_once is a new macro which handles the initialization of secret keys. It is possible to call it in the fast path. Only the initialization depends on the spinlock and is rather slow. Otherwise it should get used just before the key is used to delay the entropy extration as late as possible to get better randomness. It returns true if the key got initialized. The usage of static_keys for net_get_random_once is a bit uncommon so it needs some further explanation why this actually works: === In the simple non-HAVE_JUMP_LABEL case we actually have === no constrains to use static_key_(true|false) on keys initialized with STATIC_KEY_INIT_(FALSE|TRUE). So this path just expands in favor of the likely case that the initialization is already done. The key is initialized like this: ___done_key = { .enabled = ATOMIC_INIT(0) } The check if (!static_key_true(&___done_key)) \ expands into (pseudo code) if (!likely(___done_key > 0)) , so we take the fast path as soon as ___done_key is increased from the helper function. === If HAVE_JUMP_LABELs are available this depends === on patching of jumps into the prepared NOPs, which is done in jump_label_init at boot-up time (from start_kernel). It is forbidden and dangerous to use net_get_random_once in functions which are called before that! At compilation time NOPs are generated at the call sites of net_get_random_once. E.g. net/ipv6/inet6_hashtable.c:inet6_ehashfn (we need to call net_get_random_once two times in inet6_ehashfn, so two NOPs): 71: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 76: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) Both will be patched to the actual jumps to the end of the function to call __net_get_random_once at boot time as explained above. arch_static_branch is optimized and inlined for false as return value and actually also returns false in case the NOP is placed in the instruction stream. So in the fast case we get a "return false". But because we initialize ___done_key with (enabled != (entries & 1)) this call-site will get patched up at boot thus returning true. The final check looks like this: if (!static_key_true(&___done_key)) \ ___ret = __net_get_random_once(buf, \ expands to if (!!static_key_false(&___done_key)) \ ___ret = __net_get_random_once(buf, \ So we get true at boot time and as soon as static_key_slow_inc is called on the key it will invert the logic and return false for the fast path. static_key_slow_inc will change the branch because it got initialized with .enabled == 0. After static_key_slow_inc is called on the key the branch is replaced with a nop again. === Misc: === The helper defers the increment into a workqueue so we don't have problems calling this code from atomic sections. A seperate boolean (___done) guards the case where we enter net_get_random_once again before the increment happend. Cc: Ingo Molnar <mingo@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19 21:48:55 +02:00
net: make net_get_random_once irq safe I initial build non irq safe version of net_get_random_once because I would liked to have the freedom to defer even the extraction process of get_random_bytes until the nonblocking pool is fully seeded. I don't think this is a good idea anymore and thus this patch makes net_get_random_once irq safe. Now someone using net_get_random_once does not need to care from where it is called. Cc: David S. Miller <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-23 20:05:27 +02:00
net: introduce new macro net_get_random_once net_get_random_once is a new macro which handles the initialization of secret keys. It is possible to call it in the fast path. Only the initialization depends on the spinlock and is rather slow. Otherwise it should get used just before the key is used to delay the entropy extration as late as possible to get better randomness. It returns true if the key got initialized. The usage of static_keys for net_get_random_once is a bit uncommon so it needs some further explanation why this actually works: === In the simple non-HAVE_JUMP_LABEL case we actually have === no constrains to use static_key_(true|false) on keys initialized with STATIC_KEY_INIT_(FALSE|TRUE). So this path just expands in favor of the likely case that the initialization is already done. The key is initialized like this: ___done_key = { .enabled = ATOMIC_INIT(0) } The check if (!static_key_true(&___done_key)) \ expands into (pseudo code) if (!likely(___done_key > 0)) , so we take the fast path as soon as ___done_key is increased from the helper function. === If HAVE_JUMP_LABELs are available this depends === on patching of jumps into the prepared NOPs, which is done in jump_label_init at boot-up time (from start_kernel). It is forbidden and dangerous to use net_get_random_once in functions which are called before that! At compilation time NOPs are generated at the call sites of net_get_random_once. E.g. net/ipv6/inet6_hashtable.c:inet6_ehashfn (we need to call net_get_random_once two times in inet6_ehashfn, so two NOPs): 71: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 76: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) Both will be patched to the actual jumps to the end of the function to call __net_get_random_once at boot time as explained above. arch_static_branch is optimized and inlined for false as return value and actually also returns false in case the NOP is placed in the instruction stream. So in the fast case we get a "return false". But because we initialize ___done_key with (enabled != (entries & 1)) this call-site will get patched up at boot thus returning true. The final check looks like this: if (!static_key_true(&___done_key)) \ ___ret = __net_get_random_once(buf, \ expands to if (!!static_key_false(&___done_key)) \ ___ret = __net_get_random_once(buf, \ So we get true at boot time and as soon as static_key_slow_inc is called on the key it will invert the logic and return false for the fast path. static_key_slow_inc will change the branch because it got initialized with .enabled == 0. After static_key_slow_inc is called on the key the branch is replaced with a nop again. === Misc: === The helper defers the increment into a workqueue so we don't have problems calling this code from atomic sections. A seperate boolean (___done) guards the case where we enter net_get_random_once again before the increment happend. Cc: Ingo Molnar <mingo@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19 21:48:55 +02:00
net: make net_get_random_once irq safe I initial build non irq safe version of net_get_random_once because I would liked to have the freedom to defer even the extraction process of get_random_bytes until the nonblocking pool is fully seeded. I don't think this is a good idea anymore and thus this patch makes net_get_random_once irq safe. Now someone using net_get_random_once does not need to care from where it is called. Cc: David S. Miller <davem@davemloft.net> Cc: Eric Dumazet <edumazet@google.com> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-23 20:05:27 +02:00
net: introduce new macro net_get_random_once net_get_random_once is a new macro which handles the initialization of secret keys. It is possible to call it in the fast path. Only the initialization depends on the spinlock and is rather slow. Otherwise it should get used just before the key is used to delay the entropy extration as late as possible to get better randomness. It returns true if the key got initialized. The usage of static_keys for net_get_random_once is a bit uncommon so it needs some further explanation why this actually works: === In the simple non-HAVE_JUMP_LABEL case we actually have === no constrains to use static_key_(true|false) on keys initialized with STATIC_KEY_INIT_(FALSE|TRUE). So this path just expands in favor of the likely case that the initialization is already done. The key is initialized like this: ___done_key = { .enabled = ATOMIC_INIT(0) } The check if (!static_key_true(&___done_key)) \ expands into (pseudo code) if (!likely(___done_key > 0)) , so we take the fast path as soon as ___done_key is increased from the helper function. === If HAVE_JUMP_LABELs are available this depends === on patching of jumps into the prepared NOPs, which is done in jump_label_init at boot-up time (from start_kernel). It is forbidden and dangerous to use net_get_random_once in functions which are called before that! At compilation time NOPs are generated at the call sites of net_get_random_once. E.g. net/ipv6/inet6_hashtable.c:inet6_ehashfn (we need to call net_get_random_once two times in inet6_ehashfn, so two NOPs): 71: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 76: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) Both will be patched to the actual jumps to the end of the function to call __net_get_random_once at boot time as explained above. arch_static_branch is optimized and inlined for false as return value and actually also returns false in case the NOP is placed in the instruction stream. So in the fast case we get a "return false". But because we initialize ___done_key with (enabled != (entries & 1)) this call-site will get patched up at boot thus returning true. The final check looks like this: if (!static_key_true(&___done_key)) \ ___ret = __net_get_random_once(buf, \ expands to if (!!static_key_false(&___done_key)) \ ___ret = __net_get_random_once(buf, \ So we get true at boot time and as soon as static_key_slow_inc is called on the key it will invert the logic and return false for the fast path. static_key_slow_inc will change the branch because it got initialized with .enabled == 0. After static_key_slow_inc is called on the key the branch is replaced with a nop again. === Misc: === The helper defers the increment into a workqueue so we don't have problems calling this code from atomic sections. A seperate boolean (___done) guards the case where we enter net_get_random_once again before the increment happend. Cc: Ingo Molnar <mingo@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19 21:48:55 +02:00
net: avoid dependency of net_get_random_once on nop patching net_get_random_once depends on the static keys infrastructure to patch up the branch to the slow path during boot. This was realized by abusing the static keys api and defining a new initializer to not enable the call site while still indicating that the branch point should get patched up. This was needed to have the fast path considered likely by gcc. The static key initialization during boot up normally walks through all the registered keys and either patches in ideal nops or enables the jump site but omitted that step on x86 if ideal nops where already placed at static_key branch points. Thus net_get_random_once branches not always became active. This patch switches net_get_random_once to the ordinary static_key api and thus places the kernel fast path in the - by gcc considered - unlikely path. Microbenchmarks on Intel and AMD x86-64 showed that the unlikely path actually beats the likely path in terms of cycle cost and that different nop patterns did not make much difference, thus this switch should not be noticeable. Fixes: a48e42920ff38b ("net: introduce new macro net_get_random_once") Reported-by: Tuomas Räsänen <tuomasjjrasanen@tjjr.fi> Cc: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2014-05-11 22:59:30 +02:00
net: introduce new macro net_get_random_once net_get_random_once is a new macro which handles the initialization of secret keys. It is possible to call it in the fast path. Only the initialization depends on the spinlock and is rather slow. Otherwise it should get used just before the key is used to delay the entropy extration as late as possible to get better randomness. It returns true if the key got initialized. The usage of static_keys for net_get_random_once is a bit uncommon so it needs some further explanation why this actually works: === In the simple non-HAVE_JUMP_LABEL case we actually have === no constrains to use static_key_(true|false) on keys initialized with STATIC_KEY_INIT_(FALSE|TRUE). So this path just expands in favor of the likely case that the initialization is already done. The key is initialized like this: ___done_key = { .enabled = ATOMIC_INIT(0) } The check if (!static_key_true(&___done_key)) \ expands into (pseudo code) if (!likely(___done_key > 0)) , so we take the fast path as soon as ___done_key is increased from the helper function. === If HAVE_JUMP_LABELs are available this depends === on patching of jumps into the prepared NOPs, which is done in jump_label_init at boot-up time (from start_kernel). It is forbidden and dangerous to use net_get_random_once in functions which are called before that! At compilation time NOPs are generated at the call sites of net_get_random_once. E.g. net/ipv6/inet6_hashtable.c:inet6_ehashfn (we need to call net_get_random_once two times in inet6_ehashfn, so two NOPs): 71: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) 76: 0f 1f 44 00 00 nopl 0x0(%rax,%rax,1) Both will be patched to the actual jumps to the end of the function to call __net_get_random_once at boot time as explained above. arch_static_branch is optimized and inlined for false as return value and actually also returns false in case the NOP is placed in the instruction stream. So in the fast case we get a "return false". But because we initialize ___done_key with (enabled != (entries & 1)) this call-site will get patched up at boot thus returning true. The final check looks like this: if (!static_key_true(&___done_key)) \ ___ret = __net_get_random_once(buf, \ expands to if (!!static_key_false(&___done_key)) \ ___ret = __net_get_random_once(buf, \ So we get true at boot time and as soon as static_key_slow_inc is called on the key it will invert the logic and return false for the fast path. static_key_slow_inc will change the branch because it got initialized with .enabled == 0. After static_key_slow_inc is called on the key the branch is replaced with a nop again. === Misc: === The helper defers the increment into a workqueue so we don't have problems calling this code from atomic sections. A seperate boolean (___done) guards the case where we enter net_get_random_once again before the increment happend. Cc: Ingo Molnar <mingo@redhat.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Jason Baron <jbaron@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Eric Dumazet <edumazet@google.com> Cc: "David S. Miller" <davem@davemloft.net> Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2013-10-19 21:48:55 +02:00