net: 8021q: vlan_core: allow use list of vlans for real device

It's redundancy for the drivers to hold the list of vlans when
absolutely the same list exists in vlan core. In most cases it's
needed only to traverse the vlan devices, their vids and sync some
settings with h/w, so add API to simplify this.

At least some of these drivers also can benefit:
grep "for_each.*vid" -r drivers/net/ethernet/

drivers/net/ethernet/hisilicon/hns3/hns3_enet.c:
drivers/net/ethernet/synopsys/dwc-xlgmac-hw.c:
drivers/net/ethernet/qlogic/qlge/qlge_main.c:
drivers/net/ethernet/qlogic/qlcnic/qlcnic_main.c:
drivers/net/ethernet/via/via-rhine.c:
drivers/net/ethernet/via/via-velocity.c:
drivers/net/ethernet/intel/igb/igb_main.c:
drivers/net/ethernet/intel/ice/ice_main.c:
drivers/net/ethernet/intel/e1000/e1000_main.c:
drivers/net/ethernet/intel/i40e/i40e_main.c:
drivers/net/ethernet/intel/e1000e/netdev.c:
drivers/net/ethernet/intel/igbvf/netdev.c:
drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c:
drivers/net/ethernet/intel/ixgb/ixgb_main.c:
drivers/net/ethernet/intel/ixgbe/ixgbe_main.c:
drivers/net/ethernet/amd/xgbe/xgbe-dev.c:
drivers/net/ethernet/emulex/benet/be_main.c:
drivers/net/ethernet/neterion/vxge/vxge-main.c:
drivers/net/ethernet/adaptec/starfire.c:
drivers/net/ethernet/brocade/bna/bnad.c:

Reviewed-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/if_vlan.h

@@ -133,6 +133,9 @@ struct vlan_pcpu_stats {
 
 extern struct net_device *__vlan_find_dev_deep_rcu(struct net_device *real_dev,
 					       __be16 vlan_proto, u16 vlan_id);
+extern int vlan_for_each(struct net_device *dev,
+			 int (*action)(struct net_device *dev, int vid,
+				       void *arg), void *arg);
 extern struct net_device *vlan_dev_real_dev(const struct net_device *dev);
 extern u16 vlan_dev_vlan_id(const struct net_device *dev);
 extern __be16 vlan_dev_vlan_proto(const struct net_device *dev);
@@ -236,6 +239,14 @@ __vlan_find_dev_deep_rcu(struct net_device *real_dev,
 	return NULL;
 }
 
+static inline int
+vlan_for_each(struct net_device *dev,
+	      int (*action)(struct net_device *dev, int vid, void *arg),
+	      void *arg)
+{
+	return 0;
+}
+
 static inline struct net_device *vlan_dev_real_dev(const struct net_device *dev)
 {
 	BUG();

net/8021q/vlan_core.c

@@ -223,6 +223,33 @@ static int vlan_kill_rx_filter_info(struct net_device *dev, __be16 proto, u16 vi
 		return -ENODEV;
 }
 
+int vlan_for_each(struct net_device *dev,
+		  int (*action)(struct net_device *dev, int vid, void *arg),
+		  void *arg)
+{
+	struct vlan_vid_info *vid_info;
+	struct vlan_info *vlan_info;
+	struct net_device *vdev;
+	int ret;
+
+	ASSERT_RTNL();
+
+	vlan_info = rtnl_dereference(dev->vlan_info);
+	if (!vlan_info)
+		return 0;
+
+	list_for_each_entry(vid_info, &vlan_info->vid_list, list) {
+		vdev = vlan_group_get_device(&vlan_info->grp, vid_info->proto,
+					     vid_info->vid);
+		ret = action(vdev, vid_info->vid, arg);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(vlan_for_each);
+
 int vlan_filter_push_vids(struct vlan_info *vlan_info, __be16 proto)
 {
 	struct net_device *real_dev = vlan_info->real_dev;