| From | Ben Hutchings <> | Date | Wed, 02 Oct 2019 20:06:51 +0100 | Subject | [PATCH 3.16 22/87] sbitmap: fix improper use of smp_mb__before_atomic() |
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3.16.75-rc1 review patch. If anyone has any objections, please let me know.
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From: Andrea Parri <andrea.parri@amarulasolutions.com>
commit a0934fd2b1208458e55fc4b48f55889809fce666 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: 6c0ca7ae292ad ("sbitmap: fix wakeup hang after sbq resize") 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: Omar Sandoval <osandov@fb.com> 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> [bwh: Backported to 3.16: adjust filename] Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- block/blk-mq-tag.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/block/blk-mq-tag.c +++ b/block/blk-mq-tag.c @@ -499,7 +499,7 @@ static void bt_update_count(struct blk_m * Pairs with the memory barrier in bt_clear_tag() to ensure * that the batch size is updated before the wait counts. */ - smp_mb__before_atomic(); + smp_mb(); for (i = 0; i < BT_WAIT_QUEUES; i++) atomic_set(&bt->bs[i].wait_cnt, 1); }
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