vlan: link the upper neighbour only after registering

Otherwise users might access it without being fully registered, as per
sysfs - it only inits in register_netdevice(), so is unusable till it is
called.

CC: Patrick McHardy <kaber@trash.net>
CC: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Veaceslav Falico <vfalico@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/8021q/vlan.c

@@ -169,13 +169,13 @@ int register_vlan_dev(struct net_device *dev)
 	if (err < 0)
 		goto out_uninit_mvrp;
 
-	err = netdev_upper_dev_link(real_dev, dev);
-	if (err)
-		goto out_uninit_mvrp;
-
 	err = register_netdevice(dev);
 	if (err < 0)
-		goto out_upper_dev_unlink;
+		goto out_uninit_mvrp;
+
+	err = netdev_upper_dev_link(real_dev, dev);
+	if (err)
+		goto out_unregister_netdev;
 
 	/* Account for reference in struct vlan_dev_priv */
 	dev_hold(real_dev);
@@ -191,8 +191,8 @@ int register_vlan_dev(struct net_device *dev)
 
 	return 0;
 
-out_upper_dev_unlink:
-	netdev_upper_dev_unlink(real_dev, dev);
+out_unregister_netdev:
+	unregister_netdevice(dev);
 out_uninit_mvrp:
 	if (grp->nr_vlan_devs == 0)
 		vlan_mvrp_uninit_applicant(real_dev);