net: ip6_tunnel: Unregister catch-all devices

Similarly to the sit case, we need to remove the tunnels with no
addresses that have been moved to another network namespace.

Fixes: 0bd87628 ("ip6tnl: add x-netns support")
Signed-off-by: Hristo Venev <hristo@venev.name>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/ip6_tunnel.c

@@ -2244,6 +2244,16 @@ static void __net_exit ip6_tnl_destroy_tunnels(struct net *net, struct list_head
 			t = rtnl_dereference(t->next);
 		}
 	}
+
+	t = rtnl_dereference(ip6n->tnls_wc[0]);
+	while (t) {
+		/* If dev is in the same netns, it has already
+		 * been added to the list by the previous loop.
+		 */
+		if (!net_eq(dev_net(t->dev), net))
+			unregister_netdevice_queue(t->dev, list);
+		t = rtnl_dereference(t->next);
+	}
 }
 
 static int __net_init ip6_tnl_init_net(struct net *net)