Re: [PATCH v7 03/12] vhost: Delete useless read memory barrier

[Jason Wang]

On Fri, Aug 5, 2022 at 2:29 AM Eugenio Pérez <eperezma@redhat.com> wrote:
>
> As discussed in previous series [1], this memory barrier is useless with
> the atomic read of used idx at vhost_svq_more_used. Deleting it.
>
> [1] https://lists.nongnu.org/archive/html/qemu-devel/2022-07/msg02616.html
>
> Signed-off-by: Eugenio Pérez <eperezma@redhat.com>

Acked-by: Jason Wang <jasowang@redhat.com>

> ---
>  hw/virtio/vhost-shadow-virtqueue.c | 3 ---
>  1 file changed, 3 deletions(-)
>
> diff --git a/hw/virtio/vhost-shadow-virtqueue.c 
> b/hw/virtio/vhost-shadow-virtqueue.c
> index e6eebd0e8d..1b49bf54f2 100644
> --- a/hw/virtio/vhost-shadow-virtqueue.c
> +++ b/hw/virtio/vhost-shadow-virtqueue.c
> @@ -509,9 +509,6 @@ size_t vhost_svq_poll(VhostShadowVirtqueue *svq)
>          if (unlikely(g_get_monotonic_time() - start_us > 10e6)) {
>              return 0;
>          }
> -
> -        /* Make sure we read new used_idx */
> -        smp_rmb();
>      } while (true);
>  }
>
> --
> 2.31.1
>