From: Andrea Parri <andrea.pa...@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")
Cc: sta...@vger.kernel.org
Reported-by: "Paul E. McKenney" <paul...@linux.ibm.com>
Reported-by: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Andrea Parri <andrea.pa...@amarulasolutions.com>
Reviewed-by: Ming Lei <ming....@redhat.com>
Cc: Jens Axboe <ax...@kernel.dk>
Cc: Omar Sandoval <osan...@fb.com>
Cc: Ming Lei <ming....@redhat.com>
Cc: linux-bl...@vger.kernel.org
Cc: "Paul E. McKenney" <paul...@linux.ibm.com>
Cc: Peter Zijlstra <pet...@infradead.org>
Signed-off-by: Jens Axboe <ax...@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 lib/sbitmap.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/lib/sbitmap.c
+++ b/lib/sbitmap.c
@@ -435,7 +435,7 @@ static void sbitmap_queue_update_wake_ba
                 * to ensure that the batch size is updated before the wait
                 * counts.
                 */
-               smp_mb__before_atomic();
+               smp_mb();
                for (i = 0; i < SBQ_WAIT_QUEUES; i++)
                        atomic_set(&sbq->ws[i].wait_cnt, 1);
        }


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