net/virtio: remove unnecessary read memory barrier

As desc_is_used has a load-acquire or rte_io_rmb inside
and wait for used desc in virtqueue, it is ok to remove
virtio_rmb behind it.

Signed-off-by: Joyce Kong <joyce.kong@arm.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>
Reviewed-by: Maxime Coquelin <maxime.coquelin@redhat.com>

diff --git a/drivers/net/virtio/virtio_ethdev.c b/drivers/net/virtio/virtio_ethdev.c
index 54a6d6c..9600624 100644 (file)
--- a/drivers/net/virtio/virtio_ethdev.c
+++ b/drivers/net/virtio/virtio_ethdev.c
@@ -209,12 +209,12 @@ virtio_send_command_packed(struct virtnet_ctl *cvq,
        virtio_wmb(vq->hw->weak_barriers);
        virtqueue_notify(vq);
 
-       /* wait for used descriptors in virtqueue */
+       /* wait for used desc in virtqueue
+        * desc_is_used has a load-acquire or rte_io_rmb inside
+        */
        while (!desc_is_used(&desc[head], vq))
                usleep(100);
 
-       virtio_rmb(vq->hw->weak_barriers);
-
        /* now get used descriptors */
        vq->vq_free_cnt += nb_descs;
        vq->vq_used_cons_idx += nb_descs;