From: Andrea Parri andrea.parri@amarulasolutions.com
commit f381c6a4bd0ae0fde2d6340f1b9bb0f58d915de6 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: dac56212e8127 ("bio: skip atomic inc/dec of ->bi_cnt for most use cases") Cc: stable@vger.kernel.org Reported-by: "Paul E. McKenney" paulmck@linux.ibm.com Reported-by: Peter Zijlstra peterz@infradead.org Signed-off-by: Andrea Parri andrea.parri@amarulasolutions.com Reviewed-by: Ming 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: Jens Axboe axboe@kernel.dk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- include/linux/bio.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -237,7 +237,7 @@ static inline void bio_cnt_set(struct bi { if (count != 1) { bio->bi_flags |= (1 << BIO_REFFED); - smp_mb__before_atomic(); + smp_mb(); } atomic_set(&bio->__bi_cnt, count); }