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author | Mikulas Patocka <mpatocka@redhat.com> | 2022-08-26 09:17:08 -0400 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-08-26 09:30:25 -0700 |
commit | 8238b4579866b7c1bb99883cfe102a43db5506ff (patch) | |
tree | a61b3a10f1d6b53bc7c05b08b8b49bb84156ee2e /include/linux/buffer_head.h | |
parent | 4c612826bec1441214816827979b62f84a097e91 (diff) | |
download | linux-8238b4579866b7c1bb99883cfe102a43db5506ff.tar.gz |
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 'include/linux/buffer_head.h')
-rw-r--r-- | include/linux/buffer_head.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h index def8b8d30ccc..089c9ade4325 100644 --- a/include/linux/buffer_head.h +++ b/include/linux/buffer_head.h @@ -156,7 +156,7 @@ static __always_inline int buffer_uptodate(const struct buffer_head *bh) * make it consistent with folio_test_uptodate * pairs with smp_mb__before_atomic in set_buffer_uptodate */ - return (smp_load_acquire(&bh->b_state) & (1UL << BH_Uptodate)) != 0; + return test_bit_acquire(BH_Uptodate, &bh->b_state); } #define bh_offset(bh) ((unsigned long)(bh)->b_data & ~PAGE_MASK) |