Commit a0934fd2 authored May 20, 2019 by Andrea Parri Committed by Jens Axboe May 23, 2019

sbitmap: fix improper use of smp_mb__before_atomic()



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: 6c0ca7ae ("sbitmap: fix wakeup hang after sbq resize")
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: 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>

parent f381c6a4

lib/sbitmap.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -435,7 +435,7 @@ static void sbitmap_queue_update_wake_batch(struct sbitmap_queue *sbq,
	* to ensure that the batch size is updated before the wait		* to ensure that the batch size is updated before the wait
	* counts.		* counts.
	*/		*/
	smp_mb__before_atomic();		smp_mb();
	for (i = 0; i < SBQ_WAIT_QUEUES; i++)		for (i = 0; i < SBQ_WAIT_QUEUES; i++)
	atomic_set(&sbq->ws[i].wait_cnt, 1);		atomic_set(&sbq->ws[i].wait_cnt, 1);
	}		}