* [PATCH 4.4 078/241] bio: fix improper use of smp_mb__before_atomic()
[not found] <20190609164147.729157653@linuxfoundation.org>
@ 2019-06-09 16:40 ` Greg Kroah-Hartman
0 siblings, 0 replies; only message in thread
From: Greg Kroah-Hartman @ 2019-06-09 16:40 UTC (permalink / raw)
To: linux-kernel
Cc: Greg Kroah-Hartman, stable, Paul E. McKenney, Peter Zijlstra,
Andrea Parri, Ming Lei, Jens Axboe, linux-block
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
@@ -290,7 +290,7 @@ 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);
}
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2019-06-09 16:40 ` [PATCH 4.4 078/241] bio: fix improper use of smp_mb__before_atomic() Greg Kroah-Hartman
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