net: add infrastructure to un-offload UDP tunnel port

This adds a new NETDEV_UDP_TUNNEL_DROP_INFO event, similar to
NETDEV_UDP_TUNNEL_PUSH_INFO, to signal to un-offload ports.

This also adds udp_tunnel_drop_rx_port(), which calls
ndo_udp_tunnel_del.
Signed-off-by: NSabrina Dubroca <sd@queasysnail.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -2317,6 +2317,7 @@ struct netdev_lag_lower_state_info {
 #define NETDEV_PRECHANGEUPPER	0x001A
 #define NETDEV_CHANGELOWERSTATE	0x001B
 #define NETDEV_UDP_TUNNEL_PUSH_INFO	0x001C
+#define NETDEV_UDP_TUNNEL_DROP_INFO	0x001D
 #define NETDEV_CHANGE_TX_QUEUE_LEN	0x001E
 
 int register_netdevice_notifier(struct notifier_block *nb);

include/net/udp_tunnel.h

@@ -115,6 +115,8 @@ struct udp_tunnel_info {
 /* Notify network devices of offloadable types */
 void udp_tunnel_push_rx_port(struct net_device *dev, struct socket *sock,
 			     unsigned short type);
+void udp_tunnel_drop_rx_port(struct net_device *dev, struct socket *sock,
+			     unsigned short type);
 void udp_tunnel_notify_add_rx_port(struct socket *sock, unsigned short type);
 void udp_tunnel_notify_del_rx_port(struct socket *sock, unsigned short type);
 
@@ -124,6 +126,12 @@ static inline void udp_tunnel_get_rx_info(struct net_device *dev)
 	call_netdevice_notifiers(NETDEV_UDP_TUNNEL_PUSH_INFO, dev);
 }
 
+static inline void udp_tunnel_drop_rx_info(struct net_device *dev)
+{
+	ASSERT_RTNL();
+	call_netdevice_notifiers(NETDEV_UDP_TUNNEL_DROP_INFO, dev);
+}
+
 /* Transmit the skb using UDP encapsulation. */
 void udp_tunnel_xmit_skb(struct rtable *rt, struct sock *sk, struct sk_buff *skb,
 			 __be32 src, __be32 dst, __u8 tos, __u8 ttl,

net/ipv4/udp_tunnel.c

@@ -94,6 +94,24 @@ void udp_tunnel_push_rx_port(struct net_device *dev, struct socket *sock,
 }
 EXPORT_SYMBOL_GPL(udp_tunnel_push_rx_port);
 
+void udp_tunnel_drop_rx_port(struct net_device *dev, struct socket *sock,
+			     unsigned short type)
+{
+	struct sock *sk = sock->sk;
+	struct udp_tunnel_info ti;
+
+	if (!dev->netdev_ops->ndo_udp_tunnel_del ||
+	    !(dev->features & NETIF_F_RX_UDP_TUNNEL_PORT))
+		return;
+
+	ti.type = type;
+	ti.sa_family = sk->sk_family;
+	ti.port = inet_sk(sk)->inet_sport;
+
+	dev->netdev_ops->ndo_udp_tunnel_del(dev, &ti);
+}
+EXPORT_SYMBOL_GPL(udp_tunnel_drop_rx_port);
+
 /* Notify netdevs that UDP port started listening */
 void udp_tunnel_notify_add_rx_port(struct socket *sock, unsigned short type)
 {