Commit 01b5e7f8 authored by Andrea Parri's avatar Andrea Parri Committed by Greg Kroah-Hartman

bio: fix improper use of smp_mb__before_atomic()

commit f381c6a4 upstream.

This barrier only applies to the read-modify-write operations; in
particular, it does not apply to the atomic_set() primitive.

Replace the barrier with an smp_mb().

Fixes: dac56212 ("bio: skip atomic inc/dec of ->bi_cnt for most use cases")
Cc: stable@vger.kernel.org
Reported-by: default avatar"Paul E. McKenney" <paulmck@linux.ibm.com>
Reported-by: default avatarPeter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarAndrea Parri <andrea.parri@amarulasolutions.com>
Reviewed-by: default avatarMing Lei <ming.lei@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Ming Lei <ming.lei@redhat.com>
Cc: linux-block@vger.kernel.org
Cc: "Paul E. McKenney" <paulmck@linux.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e83d85e7
...@@ -224,7 +224,7 @@ static inline void bio_cnt_set(struct bio *bio, unsigned int count) ...@@ -224,7 +224,7 @@ static inline void bio_cnt_set(struct bio *bio, unsigned int count)
{ {
if (count != 1) { if (count != 1) {
bio->bi_flags |= (1 << BIO_REFFED); bio->bi_flags |= (1 << BIO_REFFED);
smp_mb__before_atomic(); smp_mb();
} }
atomic_set(&bio->__bi_cnt, count); atomic_set(&bio->__bi_cnt, count);
} }
......
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