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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/asm-generic/bitops/instrumented-non-atomic.h | |
parent | Merge tag 'net-6.0-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net (diff) | |
download | wireguard-linux-8238b4579866b7c1bb99883cfe102a43db5506ff.tar.xz wireguard-linux-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 'include/asm-generic/bitops/instrumented-non-atomic.h')
-rw-r--r-- | include/asm-generic/bitops/instrumented-non-atomic.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/include/asm-generic/bitops/instrumented-non-atomic.h b/include/asm-generic/bitops/instrumented-non-atomic.h index 988a3bbfba34..2b238b161a62 100644 --- a/include/asm-generic/bitops/instrumented-non-atomic.h +++ b/include/asm-generic/bitops/instrumented-non-atomic.h @@ -142,4 +142,16 @@ _test_bit(unsigned long nr, const volatile unsigned long *addr) return arch_test_bit(nr, addr); } +/** + * _test_bit_acquire - Determine, with acquire semantics, whether a bit is set + * @nr: bit number to test + * @addr: Address to start counting from + */ +static __always_inline bool +_test_bit_acquire(unsigned long nr, const volatile unsigned long *addr) +{ + instrument_atomic_read(addr + BIT_WORD(nr), sizeof(long)); + return arch_test_bit_acquire(nr, addr); +} + #endif /* _ASM_GENERIC_BITOPS_INSTRUMENTED_NON_ATOMIC_H */ |