tunnel: introduce udp_tun_rx_dst()

Introduce function udp_tun_rx_dst() to initialize tunnel dst on
receive path.

Signed-off-by: Pravin B Shelar <pshelar@nicira.com>
Reviewed-by: Jesse Gross <jesse@nicira.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/udp_tunnel.h b/include/net/udp_tunnel.h
index c491c12..35041d0 100644
--- a/include/net/udp_tunnel.h
+++ b/include/net/udp_tunnel.h
@@ -93,6 +93,10 @@
 
 void udp_tunnel_sock_release(struct socket *sock);
 
+struct metadata_dst *udp_tun_rx_dst(struct sk_buff *skb, unsigned short family,
+				    __be16 flags, __be64 tunnel_id,
+				    int md_size);
+
 static inline struct sk_buff *udp_tunnel_handle_offloads(struct sk_buff *skb,
 							 bool udp_csum)
 {