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>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 60f1080bffc7..efb93063fda1 100644
--- 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;