vhost_net: keep private_data and rx_ring synced

We get pointer ring from the exported sock, this means we should keep
rx_ring and vq->private synced during both vq stop and backend set,
otherwise we may see stale rx_ring.

Fixes: c67df11f6e480 ("vhost_net: try batch dequing from skb array")
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 60f1080..efb9306 100644 (file)
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -973,6 +973,7 @@ static struct socket *vhost_net_stop_vq(struct vhost_net *n,
        vhost_net_disable_vq(n, vq);
        vq->private_data = NULL;
        vhost_net_buf_unproduce(nvq);
+       nvq->rx_ring = NULL;
        mutex_unlock(&vq->mutex);
        return sock;
 }
@@ -1162,14 +1163,14 @@ static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
                vhost_net_disable_vq(n, vq);
                vq->private_data = sock;
                vhost_net_buf_unproduce(nvq);
-               if (index == VHOST_NET_VQ_RX)
-                       nvq->rx_ring = get_tap_ptr_ring(fd);
                r = vhost_vq_init_access(vq);
                if (r)
                        goto err_used;
                r = vhost_net_enable_vq(n, vq);
                if (r)
                        goto err_used;
+               if (index == VHOST_NET_VQ_RX)
+                       nvq->rx_ring = get_tap_ptr_ring(fd);
 
                oldubufs = nvq->ubufs;
                nvq->ubufs = ubufs;