From 91d2e76b27135873ef39b61f96ba9dd2f045f5c3 Mon Sep 17 00:00:00 2001 From: Andrea Parri <andrea.parri@amarulasolutions.com> Date: Mon, 20 May 2019 19:23:56 +0200 Subject: [PATCH] bio: fix improper use of smp_mb__before_atomic() BugLink: https://bugs.launchpad.net/bugs/1832661 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> Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com> Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com> --- include/linux/bio.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/bio.h b/include/linux/bio.h index 2049e86ecab3..2ba717f4902c 100644 --- a/include/linux/bio.h +++ b/include/linux/bio.h @@ -290,7 +290,7 @@ 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); } -- 2.30.9