net: dev: add generic protodown handler

Introduce dev_change_proto_down_generic, a generic ndo_change_proto_down
implementation, which sets the netdev carrier state according to proto_down.

This adds the ability to set protodown on vxlan and macvlan devices in a
generic way for use by control protocols like VRRPD.
Signed-off-by: Andy Roulin <aroulin@cumulusnetworks.com>
Acked-by: Roopa Prabhu <roopa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -3673,6 +3673,7 @@ int dev_get_port_parent_id(struct net_device *dev,
 			   struct netdev_phys_item_id *ppid, bool recurse);
 bool netdev_port_same_parent_id(struct net_device *a, struct net_device *b);
 int dev_change_proto_down(struct net_device *dev, bool proto_down);
+int dev_change_proto_down_generic(struct net_device *dev, bool proto_down);
 struct sk_buff *validate_xmit_skb_list(struct sk_buff *skb, struct net_device *dev, bool *again);
 struct sk_buff *dev_hard_start_xmit(struct sk_buff *skb, struct net_device *dev,
 				    struct netdev_queue *txq, int *ret);

net/core/dev.c

@@ -7954,6 +7954,25 @@ int dev_change_proto_down(struct net_device *dev, bool proto_down)
 }
 EXPORT_SYMBOL(dev_change_proto_down);
 
+/**
+ *	dev_change_proto_down_generic - generic implementation for
+ * 	ndo_change_proto_down that sets carrier according to
+ * 	proto_down.
+ *
+ *	@dev: device
+ *	@proto_down: new value
+ */
+int dev_change_proto_down_generic(struct net_device *dev, bool proto_down)
+{
+	if (proto_down)
+		netif_carrier_off(dev);
+	else
+		netif_carrier_on(dev);
+	dev->proto_down = proto_down;
+	return 0;
+}
+EXPORT_SYMBOL(dev_change_proto_down_generic);
+
 u32 __dev_xdp_query(struct net_device *dev, bpf_op_t bpf_op,
 		    enum bpf_netdev_command cmd)
 {