vlan: introduce functions to do mass addition/deletion of vids by another device

Introduce functions handy to copy vlan ids from one driver's list to
another.

Signed-off-by: Jiri Pirko <jpirko@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/8021q/vlan_core.c

@@ -321,3 +321,47 @@ void vlan_vid_del(struct net_device *dev, unsigned short vid)
 	}
 }
 EXPORT_SYMBOL(vlan_vid_del);
+
+int vlan_vids_add_by_dev(struct net_device *dev,
+			 const struct net_device *by_dev)
+{
+	struct vlan_vid_info *vid_info;
+	int err;
+
+	ASSERT_RTNL();
+
+	if (!by_dev->vlan_info)
+		return 0;
+
+	list_for_each_entry(vid_info, &by_dev->vlan_info->vid_list, list) {
+		err = vlan_vid_add(dev, vid_info->vid);
+		if (err)
+			goto unwind;
+	}
+	return 0;
+
+unwind:
+	list_for_each_entry_continue_reverse(vid_info,
+					     &by_dev->vlan_info->vid_list,
+					     list) {
+		vlan_vid_del(dev, vid_info->vid);
+	}
+
+	return err;
+}
+EXPORT_SYMBOL(vlan_vids_add_by_dev);
+
+void vlan_vids_del_by_dev(struct net_device *dev,
+			  const struct net_device *by_dev)
+{
+	struct vlan_vid_info *vid_info;
+
+	ASSERT_RTNL();
+
+	if (!by_dev->vlan_info)
+		return;
+
+	list_for_each_entry(vid_info, &by_dev->vlan_info->vid_list, list)
+		vlan_vid_del(dev, vid_info->vid);
+}
+EXPORT_SYMBOL(vlan_vids_del_by_dev);