| From f381c6a4bd0ae0fde2d6340f1b9bb0f58d915de6 Mon Sep 17 00:00:00 2001 |
| From: Andrea Parri <andrea.parri@amarulasolutions.com> |
| Date: Mon, 20 May 2019 19:23:56 +0200 |
| Subject: bio: fix improper use of smp_mb__before_atomic() |
| |
| 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 |
| @@ -224,7 +224,7 @@ 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); |
| } |