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authorMikulas Patocka <mpatocka@redhat.com>2022-08-26 09:17:08 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2022-08-26 09:30:25 -0700
commit8238b4579866b7c1bb99883cfe102a43db5506ff (patch)
treea61b3a10f1d6b53bc7c05b08b8b49bb84156ee2e /include/linux/wait_bit.h
parentMerge tag 'net-6.0-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net (diff)
downloadlinux-dev-8238b4579866b7c1bb99883cfe102a43db5506ff.tar.xz
linux-dev-8238b4579866b7c1bb99883cfe102a43db5506ff.zip
wait_on_bit: add an acquire memory barrier
There are several places in the kernel where wait_on_bit is not followed by a memory barrier (for example, in drivers/md/dm-bufio.c:new_read). On architectures with weak memory ordering, it may happen that memory accesses that follow wait_on_bit are reordered before wait_on_bit and they may return invalid data. Fix this class of bugs by introducing a new function "test_bit_acquire" that works like test_bit, but has acquire memory ordering semantics. Signed-off-by: Mikulas Patocka <mpatocka@redhat.com> Acked-by: Will Deacon <will@kernel.org> Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to '')
-rw-r--r--include/linux/wait_bit.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/include/linux/wait_bit.h b/include/linux/wait_bit.h
index 7dec36aecbd9..7725b7579b78 100644
--- a/include/linux/wait_bit.h
+++ b/include/linux/wait_bit.h
@@ -71,7 +71,7 @@ static inline int
wait_on_bit(unsigned long *word, int bit, unsigned mode)
{
might_sleep();
- if (!test_bit(bit, word))
+ if (!test_bit_acquire(bit, word))
return 0;
return out_of_line_wait_on_bit(word, bit,
bit_wait,
@@ -96,7 +96,7 @@ static inline int
wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
{
might_sleep();
- if (!test_bit(bit, word))
+ if (!test_bit_acquire(bit, word))
return 0;
return out_of_line_wait_on_bit(word, bit,
bit_wait_io,
@@ -123,7 +123,7 @@ wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
unsigned long timeout)
{
might_sleep();
- if (!test_bit(bit, word))
+ if (!test_bit_acquire(bit, word))
return 0;
return out_of_line_wait_on_bit_timeout(word, bit,
bit_wait_timeout,
@@ -151,7 +151,7 @@ wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action,
unsigned mode)
{
might_sleep();
- if (!test_bit(bit, word))
+ if (!test_bit_acquire(bit, word))
return 0;
return out_of_line_wait_on_bit(word, bit, action, mode);
}