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Commit f381c6a4 authored by Andrea Parri's avatar Andrea Parri Committed by Jens Axboe
Browse files

bio: fix improper use of smp_mb__before_atomic() 



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>
parent 389468e7

include/linux/bio.h

+1 −1
Original line number Diff line number Diff line
@@ -210,7 +210,7 @@ static inline void bio_cnt_set(struct bio *bio, unsigned int count) 
{

	if (count != 1) {

		bio->bi_flags |= (1 << BIO_REFFED);

		smp_mb__before_atomic();

		smp_mb();

	}

	atomic_set(&bio->__bi_cnt, count);

}