hv_netvsc: move VF to same namespace as netvsc device

When VF is added, the paravirtual device is already present
and may have been moved to another network namespace. For example,
sometimes the management interface is put in another net namespace
in some environments.

The VF should get moved to where the netvsc device is when the
VF is discovered. The user can move it later (if desired).
Signed-off-by: Stephen Hemminger <sthemmin@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/hyperv/netvsc_drv.c

@@ -1928,6 +1928,7 @@ static int netvsc_register_vf(struct net_device *vf_netdev)
 	struct net_device *ndev;
 	struct net_device_context *net_device_ctx;
 	struct netvsc_device *netvsc_dev;
+	int ret;
 
 	if (vf_netdev->addr_len != ETH_ALEN)
 		return NOTIFY_DONE;
@@ -1946,11 +1947,29 @@ static int netvsc_register_vf(struct net_device *vf_netdev)
 	if (!netvsc_dev || rtnl_dereference(net_device_ctx->vf_netdev))
 		return NOTIFY_DONE;
 
-	if (netvsc_vf_join(vf_netdev, ndev) != 0)
+	/* if syntihetic interface is a different namespace,
+	 * then move the VF to that namespace; join will be
+	 * done again in that context.
+	 */
+	if (!net_eq(dev_net(ndev), dev_net(vf_netdev))) {
+		ret = dev_change_net_namespace(vf_netdev,
+					       dev_net(ndev), "eth%d");
+		if (ret)
+			netdev_err(vf_netdev,
+				   "could not move to same namespace as %s: %d\n",
+				   ndev->name, ret);
+		else
+			netdev_info(vf_netdev,
+				    "VF moved to namespace with: %s\n",
+				    ndev->name);
 		return NOTIFY_DONE;
+	}
 
 	netdev_info(ndev, "VF registering: %s\n", vf_netdev->name);
 
+	if (netvsc_vf_join(vf_netdev, ndev) != 0)
+		return NOTIFY_DONE;
+
 	dev_hold(vf_netdev);
 	rcu_assign_pointer(net_device_ctx->vf_netdev, vf_netdev);
 	return NOTIFY_OK;