Dave Marchevsky says:
====================
This series adds support for refcounted local kptrs to the verifier. A local
kptr is 'refcounted' if its type contains a struct bpf_refcount field:
struct refcounted_node {
long data;
struct bpf_list_node ll;
struct bpf_refcount ref;
};
bpf_refcount is used to implement shared ownership for local kptrs.
Motivating usecase
==================
If a struct has two collection node fields, e.g.:
struct node {
long key;
long val;
struct bpf_rb_node rb;
struct bpf_list_node ll;
};
It's not currently possible to add a node to both the list and rbtree:
long bpf_prog(void *ctx)
{
struct node *n = bpf_obj_new(typeof(*n));
if (!n) { /* ... */ }
bpf_spin_lock(&lock);
bpf_list_push_back(&head, &n->ll);
bpf_rbtree_add(&root, &n->rb, less); /* Assume a resonable less() */
bpf_spin_unlock(&lock);
}
The above program will fail verification due to current owning / non-owning ref
logic: after bpf_list_push_back, n is a non-owning reference and thus cannot be
passed to bpf_rbtree_add. The only way to get an owning reference for the node
that was added is to bpf_list_pop_{front,back} it.
More generally, verifier ownership semantics expect that a node has one
owner (program, collection, or stashed in map) with exclusive ownership
of the node's lifetime. The owner free's the node's underlying memory when it
itself goes away.
Without a shared ownership concept it's impossible to express many real-world
usecases such that they pass verification.
Semantic Changes
================
Before this series, the verifier could make this statement: "whoever has the
owning reference has exclusive ownership of the referent's lifetime". As
demonstrated in the previous section, this implies that a BPF program can't
have an owning reference to some node if that node is in a collection. If
such a state were possible, the node would have multiple owners, each thinking
they have exclusive ownership. In order to support shared ownership it's
necessary to modify the exclusive ownership semantic.
After this series' changes, an owning reference has ownership of the referent's
lifetime, but it's not necessarily exclusive. The referent's underlying memory
is guaranteed to be valid (i.e. not free'd) until the reference is dropped or
used for collection insert.
This change doesn't affect UX of owning or non-owning references much:
* insert kfuncs (bpf_rbtree_add, bpf_list_push_{front,back}) still require
an owning reference arg, as ownership still must be passed to the
collection in a shared-ownership world.
* non-owning references still refer to valid memory without claiming
any ownership.
One important conclusion that followed from "exclusive ownership" statement
is no longer valid, though. In exclusive-ownership world, if a BPF prog has
an owning reference to a node, the verifier can conclude that no collection has
ownership of it. This conclusion was used to avoid runtime checking in the
implementations of insert and remove operations (""has the node already been
{inserted, removed}?").
In a shared-ownership world the aforementioned conclusion is no longer valid,
which necessitates doing runtime checking in insert and remove operation
kfuncs, and those functions possibly failing to insert or remove anything.
Luckily the verifier changes necessary to go from exclusive to shared ownership
were fairly minimal. Patches in this series which do change verifier semantics
generally have some summary dedicated to explaining why certain usecases
Just Work for shared ownership without verifier changes.
Implementation
==============
The changes in this series can be categorized as follows:
* struct bpf_refcount opaque field + plumbing
* support for refcounted kptrs in bpf_obj_new and bpf_obj_drop
* bpf_refcount_acquire kfunc
* enables shared ownershp by bumping refcount + acquiring owning ref
* support for possibly-failing collection insertion and removal
* insertion changes are more complex
If a patch's changes have some nuance to their effect - or lack of effect - on
verifier behavior, the patch summary talks about it at length.
Patch contents:
* Patch 1 removes btf_field_offs struct
* Patch 2 adds struct bpf_refcount and associated plumbing
* Patch 3 modifies semantics of bpf_obj_drop and bpf_obj_new to handle
refcounted kptrs
* Patch 4 adds bpf_refcount_acquire
* Patches 5-7 add support for possibly-failing collection insert and remove
* Patch 8 centralizes constructor-like functionality for local kptr types
* Patch 9 adds tests for new functionality
base-commit: 4a1e885c6d
Changelog:
v1 -> v2: lore.kernel.org/bpf/20230410190753.2012798-1-davemarchevsky@fb.com
Patch #s used below refer to the patch's position in v1 unless otherwise
specified.
* General
* Rebase onto latest bpf-next (base-commit updated above)
* Patch 4 - "bpf: Add bpf_refcount_acquire kfunc"
* Fix typo in summary (Alexei)
* Patch 7 - "Migrate bpf_rbtree_remove to possibly fail"
* Modify a paragraph in patch summary to more clearly state that only
bpf_rbtree_remove's non-owning ref clobbering behavior is changed by the
patch (Alexei)
* refcount_off == -1 -> refcount_off < 0 in "node type w/ both list
and rb_node fields" check, since any negative value means "no
bpf_refcount field found", and furthermore refcount_off is never
explicitly set to -1, but rather -EINVAL. (Alexei)
* Instead of just changing "btf: list_node and rb_node in same struct" test
expectation to pass instead of fail, do some refactoring to test both
"list_node, rb_node, and bpf_refcount" (success) and "list_node, rb_node,
_no_ bpf_refcount" (failure) cases. This ensures that logic change in
previous bullet point is correct.
* v1's "btf: list_node and rb_node in same struct" test changes didn't
add bpf_refcount, so the fact that btf load succeeded w/ list and
rb_nodes but no bpf_refcount field is further proof that this logic
was incorrect in v1.
* Patch 8 - "bpf: Centralize btf_field-specific initialization logic"
* Instead of doing __init_field_infer_size in kfuncs when taking
bpf_list_head type input which might've been 0-initialized in map, go
back to simple oneliner initialization. Add short comment explaining why
this is necessary. (Alexei)
* Patch 9 - "selftests/bpf: Add refcounted_kptr tests"
* Don't __always_inline helper fns in progs/refcounted_kptr.c (Alexei)
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Test refcounted local kptr functionality added in previous patches in
the series.
Usecases which pass verification:
* Add refcounted local kptr to both tree and list. Then, read and -
possibly, depending on test variant - delete from tree, then list.
* Also test doing read-and-maybe-delete in opposite order
* Stash a refcounted local kptr in a map_value, then add it to a
rbtree. Read from both, possibly deleting after tree read.
* Add refcounted local kptr to both tree and list. Then, try reading and
deleting twice from one of the collections.
* bpf_refcount_acquire of just-added non-owning ref should work, as
should bpf_refcount_acquire of owning ref just out of bpf_obj_new
Usecases which fail verification:
* The simple successful bpf_refcount_acquire cases from above should
both fail to verify if the newly-acquired owning ref is not dropped
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-10-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
All btf_fields in an object are 0-initialized by memset in
bpf_obj_init. This might not be a valid initial state for some field
types, in which case kfuncs that use the type will properly initialize
their input if it's been 0-initialized. Some BPF graph collection types
and kfuncs do this: bpf_list_{head,node} and bpf_rb_node.
An earlier patch in this series added the bpf_refcount field, for which
the 0 state indicates that the refcounted object should be free'd.
bpf_obj_init treats this field specially, setting refcount to 1 instead
of relying on scattered "refcount is 0? Must have just been initialized,
let's set to 1" logic in kfuncs.
This patch extends this treatment to list and rbtree field types,
allowing most scattered initialization logic in kfuncs to be removed.
Note that bpf_{list_head,rb_root} may be inside a BPF map, in which case
they'll be 0-initialized without passing through the newly-added logic,
so scattered initialization logic must remain for these collection root
types.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-9-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This patch modifies bpf_rbtree_remove to account for possible failure
due to the input rb_node already not being in any collection.
The function can now return NULL, and does when the aforementioned
scenario occurs. As before, on successful removal an owning reference to
the removed node is returned.
Adding KF_RET_NULL to bpf_rbtree_remove's kfunc flags - now KF_RET_NULL |
KF_ACQUIRE - provides the desired verifier semantics:
* retval must be checked for NULL before use
* if NULL, retval's ref_obj_id is released
* retval is a "maybe acquired" owning ref, not a non-owning ref,
so it will live past end of critical section (bpf_spin_unlock), and
thus can be checked for NULL after the end of the CS
BPF programs must add checks
============================
This does change bpf_rbtree_remove's verifier behavior. BPF program
writers will need to add NULL checks to their programs, but the
resulting UX looks natural:
bpf_spin_lock(&glock);
n = bpf_rbtree_first(&ghead);
if (!n) { /* ... */}
res = bpf_rbtree_remove(&ghead, &n->node);
bpf_spin_unlock(&glock);
if (!res) /* Newly-added check after this patch */
return 1;
n = container_of(res, /* ... */);
/* Do something else with n */
bpf_obj_drop(n);
return 0;
The "if (!res)" check above is the only addition necessary for the above
program to pass verification after this patch.
bpf_rbtree_remove no longer clobbers non-owning refs
====================================================
An issue arises when bpf_rbtree_remove fails, though. Consider this
example:
struct node_data {
long key;
struct bpf_list_node l;
struct bpf_rb_node r;
struct bpf_refcount ref;
};
long failed_sum;
void bpf_prog()
{
struct node_data *n = bpf_obj_new(/* ... */);
struct bpf_rb_node *res;
n->key = 10;
bpf_spin_lock(&glock);
bpf_list_push_back(&some_list, &n->l); /* n is now a non-owning ref */
res = bpf_rbtree_remove(&some_tree, &n->r, /* ... */);
if (!res)
failed_sum += n->key; /* not possible */
bpf_spin_unlock(&glock);
/* if (res) { do something useful and drop } ... */
}
The bpf_rbtree_remove in this example will always fail. Similarly to
bpf_spin_unlock, bpf_rbtree_remove is a non-owning reference
invalidation point. The verifier clobbers all non-owning refs after a
bpf_rbtree_remove call, so the "failed_sum += n->key" line will fail
verification, and in fact there's no good way to get information about
the node which failed to add after the invalidation. This patch removes
non-owning reference invalidation from bpf_rbtree_remove to allow the
above usecase to pass verification. The logic for why this is now
possible is as follows:
Before this series, bpf_rbtree_add couldn't fail and thus assumed that
its input, a non-owning reference, was in the tree. But it's easy to
construct an example where two non-owning references pointing to the same
underlying memory are acquired and passed to rbtree_remove one after
another (see rbtree_api_release_aliasing in
selftests/bpf/progs/rbtree_fail.c).
So it was necessary to clobber non-owning refs to prevent this
case and, more generally, to enforce "non-owning ref is definitely
in some collection" invariant. This series removes that invariant and
the failure / runtime checking added in this patch provide a clean way
to deal with the aliasing issue - just fail to remove.
Because the aliasing issue prevented by clobbering non-owning refs is no
longer an issue, this patch removes the invalidate_non_owning_refs
call from verifier handling of bpf_rbtree_remove. Note that
bpf_spin_unlock - the other caller of invalidate_non_owning_refs -
clobbers non-owning refs for a different reason, so its clobbering
behavior remains unchanged.
No BPF program changes are necessary for programs to remain valid as a
result of this clobbering change. A valid program before this patch
passed verification with its non-owning refs having shorter (or equal)
lifetimes due to more aggressive clobbering.
Also, update existing tests to check bpf_rbtree_remove retval for NULL
where necessary, and move rbtree_api_release_aliasing from
progs/rbtree_fail.c to progs/rbtree.c since it's now expected to pass
verification.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-8-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The linked_list tests use macros and function pointers to reduce code
duplication. Earlier in the series, bpf_list_push_{front,back} were
modified to be macros, expanding to invoke actual kfuncs
bpf_list_push_{front,back}_impl. Due to this change, a code snippet
like:
void (*p)(void *, void *) = (void *)&bpf_list_##op;
p(hexpr, nexpr);
meant to do bpf_list_push_{front,back}(hexpr, nexpr), will no longer
work as it's no longer valid to do &bpf_list_push_{front,back} since
they're no longer functions.
This patch fixes issues of this type, along with two other minor changes
- one improvement and one fix - both related to the node argument to
list_push_{front,back}.
* The fix: migration of list_push tests away from (void *, void *)
func ptr uncovered that some tests were incorrectly passing pointer
to node, not pointer to struct bpf_list_node within the node. This
patch fixes such issues (CHECK(..., f) -> CHECK(..., &f->node))
* The improvement: In linked_list tests, the struct foo type has two
list_node fields: node and node2, at byte offsets 0 and 40 within
the struct, respectively. Currently node is used in ~all tests
involving struct foo and lists. The verifier needs to do some work
to account for the offset of bpf_list_node within the node type, so
using node2 instead of node exercises that logic more in the tests.
This patch migrates linked_list tests to use node2 instead of node.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-7-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Consider this code snippet:
struct node {
long key;
bpf_list_node l;
bpf_rb_node r;
bpf_refcount ref;
}
int some_bpf_prog(void *ctx)
{
struct node *n = bpf_obj_new(/*...*/), *m;
bpf_spin_lock(&glock);
bpf_rbtree_add(&some_tree, &n->r, /* ... */);
m = bpf_refcount_acquire(n);
bpf_rbtree_add(&other_tree, &m->r, /* ... */);
bpf_spin_unlock(&glock);
/* ... */
}
After bpf_refcount_acquire, n and m point to the same underlying memory,
and that node's bpf_rb_node field is being used by the some_tree insert,
so overwriting it as a result of the second insert is an error. In order
to properly support refcounted nodes, the rbtree and list insert
functions must be allowed to fail. This patch adds such support.
The kfuncs bpf_rbtree_add, bpf_list_push_{front,back} are modified to
return an int indicating success/failure, with 0 -> success, nonzero ->
failure.
bpf_obj_drop on failure
=======================
Currently the only reason an insert can fail is the example above: the
bpf_{list,rb}_node is already in use. When such a failure occurs, the
insert kfuncs will bpf_obj_drop the input node. This allows the insert
operations to logically fail without changing their verifier owning ref
behavior, namely the unconditional release_reference of the input
owning ref.
With insert that always succeeds, ownership of the node is always passed
to the collection, since the node always ends up in the collection.
With a possibly-failed insert w/ bpf_obj_drop, ownership of the node
is always passed either to the collection (success), or to bpf_obj_drop
(failure). Regardless, it's correct to continue unconditionally
releasing the input owning ref, as something is always taking ownership
from the calling program on insert.
Keeping owning ref behavior unchanged results in a nice default UX for
insert functions that can fail. If the program's reaction to a failed
insert is "fine, just get rid of this owning ref for me and let me go
on with my business", then there's no reason to check for failure since
that's default behavior. e.g.:
long important_failures = 0;
int some_bpf_prog(void *ctx)
{
struct node *n, *m, *o; /* all bpf_obj_new'd */
bpf_spin_lock(&glock);
bpf_rbtree_add(&some_tree, &n->node, /* ... */);
bpf_rbtree_add(&some_tree, &m->node, /* ... */);
if (bpf_rbtree_add(&some_tree, &o->node, /* ... */)) {
important_failures++;
}
bpf_spin_unlock(&glock);
}
If we instead chose to pass ownership back to the program on failed
insert - by returning NULL on success or an owning ref on failure -
programs would always have to do something with the returned ref on
failure. The most likely action is probably "I'll just get rid of this
owning ref and go about my business", which ideally would look like:
if (n = bpf_rbtree_add(&some_tree, &n->node, /* ... */))
bpf_obj_drop(n);
But bpf_obj_drop isn't allowed in a critical section and inserts must
occur within one, so in reality error handling would become a
hard-to-parse mess.
For refcounted nodes, we can replicate the "pass ownership back to
program on failure" logic with this patch's semantics, albeit in an ugly
way:
struct node *n = bpf_obj_new(/* ... */), *m;
bpf_spin_lock(&glock);
m = bpf_refcount_acquire(n);
if (bpf_rbtree_add(&some_tree, &n->node, /* ... */)) {
/* Do something with m */
}
bpf_spin_unlock(&glock);
bpf_obj_drop(m);
bpf_refcount_acquire is used to simulate "return owning ref on failure".
This should be an uncommon occurrence, though.
Addition of two verifier-fixup'd args to collection inserts
===========================================================
The actual bpf_obj_drop kfunc is
bpf_obj_drop_impl(void *, struct btf_struct_meta *), with bpf_obj_drop
macro populating the second arg with 0 and the verifier later filling in
the arg during insn fixup.
Because bpf_rbtree_add and bpf_list_push_{front,back} now might do
bpf_obj_drop, these kfuncs need a btf_struct_meta parameter that can be
passed to bpf_obj_drop_impl.
Similarly, because the 'node' param to those insert functions is the
bpf_{list,rb}_node within the node type, and bpf_obj_drop expects a
pointer to the beginning of the node, the insert functions need to be
able to find the beginning of the node struct. A second
verifier-populated param is necessary: the offset of {list,rb}_node within the
node type.
These two new params allow the insert kfuncs to correctly call
__bpf_obj_drop_impl:
beginning_of_node = bpf_rb_node_ptr - offset
if (already_inserted)
__bpf_obj_drop_impl(beginning_of_node, btf_struct_meta->record);
Similarly to other kfuncs with "hidden" verifier-populated params, the
insert functions are renamed with _impl prefix and a macro is provided
for common usage. For example, bpf_rbtree_add kfunc is now
bpf_rbtree_add_impl and bpf_rbtree_add is now a macro which sets
"hidden" args to 0.
Due to the two new args BPF progs will need to be recompiled to work
with the new _impl kfuncs.
This patch also rewrites the "hidden argument" explanation to more
directly say why the BPF program writer doesn't need to populate the
arguments with anything meaningful.
How does this new logic affect non-owning references?
=====================================================
Currently, non-owning refs are valid until the end of the critical
section in which they're created. We can make this guarantee because, if
a non-owning ref exists, the referent was added to some collection. The
collection will drop() its nodes when it goes away, but it can't go away
while our program is accessing it, so that's not a problem. If the
referent is removed from the collection in the same CS that it was added
in, it can't be bpf_obj_drop'd until after CS end. Those are the only
two ways to free the referent's memory and neither can happen until
after the non-owning ref's lifetime ends.
On first glance, having these collection insert functions potentially
bpf_obj_drop their input seems like it breaks the "can't be
bpf_obj_drop'd until after CS end" line of reasoning. But we care about
the memory not being _freed_ until end of CS end, and a previous patch
in the series modified bpf_obj_drop such that it doesn't free refcounted
nodes until refcount == 0. So the statement can be more accurately
rewritten as "can't be free'd until after CS end".
We can prove that this rewritten statement holds for any non-owning
reference produced by collection insert functions:
* If the input to the insert function is _not_ refcounted
* We have an owning reference to the input, and can conclude it isn't
in any collection
* Inserting a node in a collection turns owning refs into
non-owning, and since our input type isn't refcounted, there's no
way to obtain additional owning refs to the same underlying
memory
* Because our node isn't in any collection, the insert operation
cannot fail, so bpf_obj_drop will not execute
* If bpf_obj_drop is guaranteed not to execute, there's no risk of
memory being free'd
* Otherwise, the input to the insert function is refcounted
* If the insert operation fails due to the node's list_head or rb_root
already being in some collection, there was some previous successful
insert which passed refcount to the collection
* We have an owning reference to the input, it must have been
acquired via bpf_refcount_acquire, which bumped the refcount
* refcount must be >= 2 since there's a valid owning reference and the
node is already in a collection
* Insert triggering bpf_obj_drop will decr refcount to >= 1, never
resulting in a free
So although we may do bpf_obj_drop during the critical section, this
will never result in memory being free'd, and no changes to non-owning
ref logic are needed in this patch.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-6-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Currently, BPF programs can interact with the lifetime of refcounted
local kptrs in the following ways:
bpf_obj_new - Initialize refcount to 1 as part of new object creation
bpf_obj_drop - Decrement refcount and free object if it's 0
collection add - Pass ownership to the collection. No change to
refcount but collection is responsible for
bpf_obj_dropping it
In order to be able to add a refcounted local kptr to multiple
collections we need to be able to increment the refcount and acquire a
new owning reference. This patch adds a kfunc, bpf_refcount_acquire,
implementing such an operation.
bpf_refcount_acquire takes a refcounted local kptr and returns a new
owning reference to the same underlying memory as the input. The input
can be either owning or non-owning. To reinforce why this is safe,
consider the following code snippets:
struct node *n = bpf_obj_new(typeof(*n)); // A
struct node *m = bpf_refcount_acquire(n); // B
In the above snippet, n will be alive with refcount=1 after (A), and
since nothing changes that state before (B), it's obviously safe. If
n is instead added to some rbtree, we can still safely refcount_acquire
it:
struct node *n = bpf_obj_new(typeof(*n));
struct node *m;
bpf_spin_lock(&glock);
bpf_rbtree_add(&groot, &n->node, less); // A
m = bpf_refcount_acquire(n); // B
bpf_spin_unlock(&glock);
In the above snippet, after (A) n is a non-owning reference, and after
(B) m is an owning reference pointing to the same memory as n. Although
n has no ownership of that memory's lifetime, it's guaranteed to be
alive until the end of the critical section, and n would be clobbered if
we were past the end of the critical section, so it's safe to bump
refcount.
Implementation details:
* From verifier's perspective, bpf_refcount_acquire handling is similar
to bpf_obj_new and bpf_obj_drop. Like the former, it returns a new
owning reference matching input type, although like the latter, type
can be inferred from concrete kptr input. Verifier changes in
{check,fixup}_kfunc_call and check_kfunc_args are largely copied from
aforementioned functions' verifier changes.
* An exception to the above is the new KF_ARG_PTR_TO_REFCOUNTED_KPTR
arg, indicated by new "__refcounted_kptr" kfunc arg suffix. This is
necessary in order to handle both owning and non-owning input without
adding special-casing to "__alloc" arg handling. Also a convenient
place to confirm that input type has bpf_refcount field.
* The implemented kfunc is actually bpf_refcount_acquire_impl, with
'hidden' second arg that the verifier sets to the type's struct_meta
in fixup_kfunc_call.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-5-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A local kptr is considered 'refcounted' when it is of a type that has a
bpf_refcount field. When such a kptr is created, its refcount should be
initialized to 1; when destroyed, the object should be free'd only if a
refcount decr results in 0 refcount.
Existing logic always frees the underlying memory when destroying a
local kptr, and 0-initializes all btf_record fields. This patch adds
checks for "is local kptr refcounted?" and new logic for that case in
the appropriate places.
This patch focuses on changing existing semantics and thus conspicuously
does _not_ provide a way for BPF programs in increment refcount. That
follows later in the series.
__bpf_obj_drop_impl is modified to do the right thing when it sees a
refcounted type. Container types for graph nodes (list, tree, stashed in
map) are migrated to use __bpf_obj_drop_impl as a destructor for their
nodes instead of each having custom destruction code in their _free
paths. Now that "drop" isn't a synonym for "free" when the type is
refcounted it makes sense to centralize this logic.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-4-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
A 'struct bpf_refcount' is added to the set of opaque uapi/bpf.h types
meant for use in BPF programs. Similarly to other opaque types like
bpf_spin_lock and bpf_rbtree_node, the verifier needs to know where in
user-defined struct types a bpf_refcount can be located, so necessary
btf_record plumbing is added to enable this. bpf_refcount is sized to
hold a refcount_t.
Similarly to bpf_spin_lock, the offset of a bpf_refcount is cached in
btf_record as refcount_off in addition to being in the field array.
Caching refcount_off makes sense for this field because further patches
in the series will modify functions that take local kptrs (e.g.
bpf_obj_drop) to change their behavior if the type they're operating on
is refcounted. So enabling fast "is this type refcounted?" checks is
desirable.
No such verifier behavior changes are introduced in this patch, just
logic to recognize 'struct bpf_refcount' in btf_record.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-3-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
The btf_field_offs struct contains (offset, size) for btf_record fields,
sorted by offset. btf_field_offs is always used in conjunction with
btf_record, which has btf_field 'fields' array with (offset, type), the
latter of which btf_field_offs' size is derived from via
btf_field_type_size.
This patch adds a size field to struct btf_field and sorts btf_record's
fields by offset, making it possible to get rid of btf_field_offs. Less
data duplication and less code complexity results.
Since btf_field_offs' lifetime closely followed the btf_record used to
populate it, most complexity wins are from removal of initialization
code like:
if (btf_record_successfully_initialized) {
foffs = btf_parse_field_offs(rec);
if (IS_ERR_OR_NULL(foffs))
// free the btf_record and return err
}
Other changes in this patch are pretty mechanical:
* foffs->field_off[i] -> rec->fields[i].offset
* foffs->field_sz[i] -> rec->fields[i].size
* Sort rec->fields in btf_parse_fields before returning
* It's possible that this is necessary independently of other
changes in this patch. btf_record_find in syscall.c expects
btf_record's fields to be sorted by offset, yet there's no
explicit sorting of them before this patch, record's fields are
populated in the order they're read from BTF struct definition.
BTF docs don't say anything about the sortedness of struct fields.
* All functions taking struct btf_field_offs * input now instead take
struct btf_record *. All callsites of these functions already have
access to the correct btf_record.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230415201811.343116-2-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
- Fix for a stable patch: Fix failure attaching when vid_hdr offset equals to (sub)page size
- Fix for a deadlock in UBI's worker thread
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Merge tag 'ubifs-for-linus-6.3-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs
Pull UBI fixes from Richard Weinberger:
- Fix failure to attach when vid_hdr offset equals the (sub)page size
- Fix for a deadlock in UBI's worker thread
* tag 'ubifs-for-linus-6.3-rc7' of git://git.kernel.org/pub/scm/linux/kernel/git/rw/ubifs:
ubi: Fix failure attaching when vid_hdr offset equals to (sub)page size
ubi: Fix deadlock caused by recursively holding work_sem
smb311_decode_neg_context() doesn't properly check against SMB packet
boundaries prior to accessing individual negotiate context entries. This
is due to the length check omitting the eight byte smb2_neg_context
header, as well as incorrect decrementing of len_of_ctxts.
Fixes: 5100d8a3fe ("SMB311: Improve checking of negotiate security contexts")
Reported-by: Volker Lendecke <vl@samba.org>
Reviewed-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Signed-off-by: David Disseldorp <ddiss@suse.de>
Signed-off-by: Steve French <stfrench@microsoft.com>
Statically initialized objects are usually not initialized via the init()
function of the subsystem. They are special cased and the subsystem
provides a function to validate whether an object which is not yet tracked
by debugobjects is statically initialized. This means the object is started
to be tracked on first use, e.g. activation.
This works perfectly fine, unless there are two concurrent operations on
that object. Schspa decoded the problem:
T0 T1
debug_object_assert_init(addr)
lock_hash_bucket()
obj = lookup_object(addr);
if (!obj) {
unlock_hash_bucket();
- > preemption
lock_subsytem_object(addr);
activate_object(addr)
lock_hash_bucket();
obj = lookup_object(addr);
if (!obj) {
unlock_hash_bucket();
if (is_static_object(addr))
init_and_track(addr);
lock_hash_bucket();
obj = lookup_object(addr);
obj->state = ACTIVATED;
unlock_hash_bucket();
subsys function modifies content of addr,
so static object detection does
not longer work.
unlock_subsytem_object(addr);
if (is_static_object(addr)) <- Fails
debugobject emits a warning and invokes the fixup function which
reinitializes the already active object in the worst case.
This race exists forever, but was never observed until mod_timer() got a
debug_object_assert_init() added which is outside of the timer base lock
held section right at the beginning of the function to cover the lockless
early exit points too.
Rework the code so that the lookup, the static object check and the
tracking object association happens atomically under the hash bucket
lock. This prevents the issue completely as all callers are serialized on
the hash bucket lock and therefore cannot observe inconsistent state.
Fixes: 3ac7fe5a4a ("infrastructure to debug (dynamic) objects")
Reported-by: syzbot+5093ba19745994288b53@syzkaller.appspotmail.com
Debugged-by: Schspa Shi <schspa@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Link: https://syzkaller.appspot.com/bug?id=22c8a5938eab640d1c6bcc0e3dc7be519d878462
Link: https://lore.kernel.org/lkml/20230303161906.831686-1-schspa@gmail.com
Link: https://lore.kernel.org/r/87zg7dzgao.ffs@tglx
For io_rsrc_ref_quiesce() to progress it should execute all task_work
items, including deferred ones. However, currently nobody would wake us,
and so let's set ctx->cq_wait_nr, so io_req_local_work_add() would wake
us up.
Fixes: c0e0d6ba25 ("io_uring: add IORING_SETUP_DEFER_TASKRUN")
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/f1a90d1bc5ebf096475b018fed52e54f3b89d4af.1681395792.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Replace completions with waitqueues for rsrc data quiesce, the main
wakeup condition is when data refs hit zero. Note that data refs are
only changes under ->uring_lock, so we prepare before mutex_unlock()
reacquire it after taking the lock back. This change will be needed
in the next patch.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/1d0dbc74b3b4fd67c8f01819e680c5e0da252956.1681395792.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Add a constant IO_NOTIF_UBUF_FLAGS for struct ubuf_info flags that
notifications use. That should minimise merge conflicts for planned
changes touching both io_uring and net at the same time.
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
A few more changes. Some were dependent on fixes that are now upstream
and in char-misc-next.
st,lsm6dsx:
- Add an ACPI ID (SMO8B30) and mount matrix (ROTM) seen in the wild.
ti,palmas
- Take probe fully devm managed.
- Add threshold event support (after some rework)
- Stop changing the event config on suspend and resume.
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Merge tag 'iio-for-6.4b' of https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio into char-misc-next
Jonathan writes:
2nd set of IIO features and cleanups for the 6.4 cycle.
A few more changes. Some were dependent on fixes that are now upstream
and in char-misc-next.
st,lsm6dsx:
- Add an ACPI ID (SMO8B30) and mount matrix (ROTM) seen in the wild.
ti,palmas
- Take probe fully devm managed.
- Add threshold event support (after some rework)
- Stop changing the event config on suspend and resume.
* tag 'iio-for-6.4b' of https://git.kernel.org/pub/scm/linux/kernel/git/jic23/iio:
iio: adc: palmas: don't alter event config on suspend/resume
iio: adc: palmas: add support for iio threshold events
iio: adc: palmas: always reset events on unload
iio: adc: palmas: move eventX_enable into palmas_adc_event
iio: adc: palmas: use iio_event_direction for threshold polarity
iio: adc: palmas: replace "wakeup" with "event"
iio: adc: palmas: remove adc_wakeupX_data
iio: adc: palmas: Take probe fully device managed.
iio: imu: lsm6dsx: Add ACPI mount matrix retrieval
iio: imu: lsm6dsx: Support SMO8B30 ACPI ID for LSM6DS3TR-C
One small fix to SCSI Enclosure Services to fix a regression caused by
another recent fix.
Signed-off-by: James E.J. Bottomley <jejb@linux.ibm.com>
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Merge tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi
Pull SCSI fix from James Bottomley:
"One small fix to SCSI Enclosure Services to fix a regression caused by
another recent fix"
* tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: ses: Handle enclosure with just a primary component gracefully
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Merge tag 'io_uring-6.3-2023-04-14' of git://git.kernel.dk/linux
Pull io_uring fix from Jens Axboe:
"Just a small tweak to when task_work needs redirection, marked for
stable as well"
* tag 'io_uring-6.3-2023-04-14' of git://git.kernel.dk/linux:
io_uring: complete request via task work in case of DEFER_TASKRUN
The Image Sensing Interface (ISI) combines image processing pipelines
with DMA engines to process and capture frames originating from a
variety of sources. The inputs to the ISI go through Pixel Link
interfaces, and their number and nature is SoC-dependent. They cover
both capture interfaces (MIPI CSI-2 RX, HDMI RX) and memory inputs.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Add blank lines as reported by checkpatch.pl as below
CHECK: Please use a blank line after function/struct/union/enum declarations
Signed-off-by: Srihari S <sriharisat@gmail.com>
Link: https://lore.kernel.org/r/1680966983-11609-1-git-send-email-sriharisat@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Check for hardware RTL8192SE is done in function _rtl92e_pci_probe()
directly and also two lines later in function rtl92e_check_adapter().
Remove top level check to increase readability.
This pci_read does not follow a pci_write to ensure data is written to
the device.
Signed-off-by: Philipp Hortmann <philipp.g.hortmann@gmail.com>
Link: https://lore.kernel.org/r/4126cca73739c75b1a0379af2ef8b0c63a705639.1680902603.git.philipp.g.hortmann@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The greybus loopback test tool does not belong burried down in a
driver-specific directory. If it is needed, it should be somewhere
else, like in the testing directory. But as the loopback driver is
probably never going to be merged out of the staging directory, let's
just delete the test alltogether for now. If it's needed in the future,
it can be brought back with a revert.
Also, having an Android.mk file in the kernel source tree breaks some
Android build systems when trying to build from a read-only source tree,
the report of which prompted this being a good reason to remove it as
well.
Cc: Johan Hovold <johan@kernel.org>
Cc: Jack Schofield <schofija@oregonstate.edu>
Cc: Vaibhav Nagare <vnagare@redhat.com>
Cc: greybus-dev@lists.linaro.org
Acked-by: Alex Elder <elder@linaro.org>
Link: https://lore.kernel.org/r/2023040613-huntsman-goldsmith-4a41@gregkh
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The _DSM used to get sensor variables like CsiPort returns the wrong
csi-port for the front OV2680 sensor on the Lenovo Ideapad Miix 310
add a gmin_vars DMI quirk / override setting the right CsiPort.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
On some devices the _DSM sensor-info table contains wrong info,
move the DMI quirk handling up to above the _DSM table check
to allow DMI quirks to override wrong info in the _DSM table.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Remove the struct atomisp_sub_device.
This was used for 2 things:
1. In dev_dbg() messages
2. To set the name of the v4l2_subdev for each struct atomisp_sub_device
Now that only 1 subdev is used neither is useful anymore. Remove the _%d
postfix from the v4l2_subdev name and remove the logging of the asd index
from the dev_dbg() messages.
In case of the atomisp_s_input() check to see if an input/sensor has
already been assigned to another subdev the entire check no longer
makes sense, so instead of changing the dev_err() message there just
drop the entire check.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
With support for depth mode gone there really is no need to support
streaming from 2 sensors at once. As discussed and acked on the list
(see Link tag) it is desirable to drop support for this since it
involves quite a lot of special handling / hacks in the code.
This initial commit limits itself to a minimum set of changes to switch
to 1 struct atomisp_sub_device / 1 stream. Further commits will actually
remove / cleanup much of the special handling.
Likewise this initial commit also deliberately skips the opportunity to
turn some multi-line statements into single-line statements, so as to
keep the diff small / easier to review.
Link: https://lore.kernel.org/linux-media/5309d845-063b-6dd9-529d-0f82654290f2@redhat.com/
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
atomisp_set_fmt() first calls:
v4l2_subdev_call(isp->inputs[asd->input_curr].camera,
pad, set_fmt, ...);
with v4l2_subdev_format.which set to V4L2_SUBDEV_FORMAT_ACTIVE and then
reduces width + height by padding_w / padding_h followed by calling
atomisp_try_fmt() which then sets res_overflow if the requested resolution
is larger then the sensor's max resolution, but that will never happen
since we are requesting for the result of a set_fmt call minus padding,
so res_overflow will always be false.
And when called with a res_overflow parameter, combined with there
being no overflow then atomisp_try_fmt() does not change the passed
in width/height.
Except when using JPEG or CUSTOM_M10MO_RAW as pixelformat, then
atomisp_try_fmt() does change the width/height but in that case
atomisp_set_fmt actually restores the old widht/height which it
has saved before the atomisp_try_fmt() call. So this too is a no-op.
TL;DR: The atomisp_try_fmt() call in atomisp_set_fmt() is a no-op,
remove it.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Remove the unused ATOM_ISP_MAX_WIDTH_TMP and ATOM_ISP_MAX_HEIGHT_TMP
defines.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
snr_mbus_fmt is a local variable pointing to a substruct of another local
variable which really just makes the code harder to read / follow,
so drop it.
And likewise also drop the stream_info local variable.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
The custom V4L2_CID_FMT_AUTO control, which defaults to true
controls whether the atomisp driver will automatically configure
the sensor and ISP settings to match.
This is necessary to make normal v4l2 apps to work. We do eventually
want to add libcamera support, but even then moving this to userspace
does not give any added value, while breaking classic v4l2 apps.
Moreover we really don't know all the exact pipeline constraints,
so moving this to userspace/libcamera will be tricky thus it is best
to keep the current in kernel code for this and make the kernel
unconditionally do this.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Remove code to check / adjust code between video and preview /
capture and view-finder nodes now that we no longer support
continuous mode and this no longer support streaming from 2
/dev/video# nodes at the same time.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
atomisp_ioctl.h contains the atomisp_[start|stop]_streaming() function
prototypes 2 times. Drop one of the copies of the prototypes.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
The DSDT of all Windows BYT / CHT devices which I have seen has proper
ACPI powermagement for the clk and regulators used by the sensors.
So there is no need for the whole custom atomisp_gmin custom code to
disable the ACPI pm and directly poke at the PMIC for this.
Replace all the atomisp_gmin usage with using the new
atomisp_register_sensor_no_gmin() / atomisp_unregister_subdev()
helpers which allow registering a sensor with the atomisp code
without using any of the atomisp_gmin power-management code.
Note eventually these calls should be replaced by the standard
v4l2_async_register_subdev_sensor() mechanism.
But this first requires a bunch of work to the atomisp main code
to make it set the necessary fwnodes up, similar to how
drivers/media/pci/intel/ipu3/cio2-bridge.c does this.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Use devm_kzalloc() to allocate the data struct. It is always free-ed as
the last step of probe-error-exit or remove, so it can be devm-managed.
This will make unwinding things easier when support is added to the gc0310
code to use standard GPIO APIs instead of the custom atomisp_gmin code.
This also allows dropping the out_free label and use direct return
on errors.
This may seem like a functional change since the out_free label also
did a v4l2_device_unregister_subdev() but at the 1 changed return
the device is not registered yet, so that always is a no-op and can
be dropped.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Add runtime-pm support. This is a preparation patch for letting
ACPI deal with the regulators and clocks instead of the DIY code
in atomisp_gmin_platform.c.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
