vlan: allow to change type when no vlan device is hooked on netdev

vlan_info might be present but still no vlan devices might be there.
That is in case of vlan0 automatically added.

So in that case, allow to change netdev type.

Reported-by: Jon Stanley <jstanley@rmrf.net>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 1 deletions

diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c
index 9096bcb08132..ee070722a3a3 100644
--- a/net/8021q/vlan.c
+++ b/net/8021q/vlan.c
@@ -463,7 +463,9 @@ static int vlan_device_event(struct notifier_block *unused, unsigned long event,
 
         case NETDEV_PRE_TYPE_CHANGE:
                 /* Forbid underlaying device to change its type. */
-                return NOTIFY_BAD;
+                if (vlan_uses_dev(dev))
+                        return NOTIFY_BAD;
+                break;
 
         case NETDEV_NOTIFY_PEERS:
         case NETDEV_BONDING_FAILOVER: