vlan: add helper which can be called to see if device is used by vlan

also, remove unused vlan_info definition from header

CC: Patrick McHardy <kaber@trash.net>
Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/if_vlan.h

@@ -74,8 +74,6 @@ static inline struct vlan_ethhdr *vlan_eth_hdr(const struct sk_buff *skb)
 /* found in socket.c */
 extern void vlan_ioctl_set(int (*hook)(struct net *, void __user *));
 
-struct vlan_info;
-
 static inline int is_vlan_dev(struct net_device *dev)
 {
         return dev->priv_flags & IFF_802_1Q_VLAN;
@@ -101,6 +99,8 @@ extern int vlan_vids_add_by_dev(struct net_device *dev,
 				const struct net_device *by_dev);
 extern void vlan_vids_del_by_dev(struct net_device *dev,
 				 const struct net_device *by_dev);
+
+extern bool vlan_uses_dev(const struct net_device *dev);
 #else
 static inline struct net_device *
 __vlan_find_dev_deep(struct net_device *real_dev, u16 vlan_id)
@@ -151,6 +151,11 @@ static inline void vlan_vids_del_by_dev(struct net_device *dev,
 					const struct net_device *by_dev)
 {
 }
+
+static inline bool vlan_uses_dev(const struct net_device *dev)
+{
+	return false;
+}
 #endif
 
 /**

net/8021q/vlan_core.c

@@ -368,3 +368,9 @@ void vlan_vids_del_by_dev(struct net_device *dev,
 		vlan_vid_del(dev, vid_info->vid);
 }
 EXPORT_SYMBOL(vlan_vids_del_by_dev);
+
+bool vlan_uses_dev(const struct net_device *dev)
+{
+	return rtnl_dereference(dev->vlan_info) ? true : false;
+}
+EXPORT_SYMBOL(vlan_uses_dev);