On Mon, Apr 29, 2019 at 10:14:59PM +0200, Andrea Parri wrote:
> 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: stable@xxxxxxxxxxxxxxx
> Reported-by: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxx>
> Reported-by: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Signed-off-by: Andrea Parri <andrea.parri@xxxxxxxxxxxxxxxxxxxx>
> Cc: Jens Axboe <axboe@xxxxxxxxx>
> Cc: Omar Sandoval <osandov@xxxxxx>
> Cc: linux-block@xxxxxxxxxxxxxxx
> ---
> lib/sbitmap.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/lib/sbitmap.c b/lib/sbitmap.c
> index 155fe38756ecf..4a7fc4915dfc6 100644
> --- a/lib/sbitmap.c
> +++ b/lib/sbitmap.c
> @@ -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
> * counts.
> */
> - smp_mb__before_atomic();
> + smp_mb();
> for (i = 0; i < SBQ_WAIT_QUEUES; i++)
> atomic_set(&sbq->ws[i].wait_cnt, 1);
> }
> --
> 2.7.4
>
sbitmap_queue_update_wake_batch() won't be called in fast path, and
the fix is correct too, so:
Reviewed-by: Ming Lei <ming.lei@xxxxxxxxxx>
thanks,
Ming
