vhost-net: do not crash if backend is not present

Do not crash when backend is not present while enabling the ring. A
following patch will save the enabled state so it can be restored once
the backend is started.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Tested-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Reviewed-by: Victor Kaplansky <victork@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

diff --git a/hw/net/vhost_net.c b/hw/net/vhost_net.c
index 6e1032f..805a0df 100644 (file)
--- a/hw/net/vhost_net.c
+++ b/hw/net/vhost_net.c
@@ -401,8 +401,13 @@ VHostNetState *get_vhost_net(NetClientState *nc)
 int vhost_set_vring_enable(NetClientState *nc, int enable)
 {
     VHostNetState *net = get_vhost_net(nc);
-    const VhostOps *vhost_ops = net->dev.vhost_ops;
+    const VhostOps *vhost_ops;
+
+    if (!net) {
+        return 0;
+    }
 
+    vhost_ops = net->dev.vhost_ops;
     if (vhost_ops->vhost_set_vring_enable) {
         return vhost_ops->vhost_set_vring_enable(&net->dev, enable);
     }