ipv4: rename and move ip_route_output_tunnel()

At the moment ip_route_output_tunnel() is used only by bareudp.
Ideally, other UDP tunnel implementations should use it, but to do so
the function needs to accept new parameters that are specific for UDP
tunnels, such as the ports.

Prepare for these changes by renaming the function to
udp_tunnel_dst_lookup() and move it to file
net/ipv4/udp_tunnel_core.c.
Suggested-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/bareudp.c

@@ -306,7 +306,7 @@ static int bareudp_xmit_skb(struct sk_buff *skb, struct net_device *dev,
 	if (!sock)
 		return -ESHUTDOWN;
 
-	rt = ip_route_output_tunnel(skb, dev, bareudp->net, &saddr, info,
+	rt = udp_tunnel_dst_lookup(skb, dev, bareudp->net, &saddr, info,
 				   IPPROTO_UDP, use_cache);
 
 	if (IS_ERR(rt))
@@ -483,7 +483,7 @@ static int bareudp_fill_metadata_dst(struct net_device *dev,
 		struct rtable *rt;
 		__be32 saddr;
 
-		rt = ip_route_output_tunnel(skb, dev, bareudp->net, &saddr,
+		rt = udp_tunnel_dst_lookup(skb, dev, bareudp->net, &saddr,
 					   info, IPPROTO_UDP, use_cache);
 		if (IS_ERR(rt))
 			return PTR_ERR(rt);

include/net/route.h

@@ -136,12 +136,6 @@ static inline struct rtable *__ip_route_output_key(struct net *net,
 
 struct rtable *ip_route_output_flow(struct net *, struct flowi4 *flp,
 				    const struct sock *sk);
-struct rtable *ip_route_output_tunnel(struct sk_buff *skb,
-				      struct net_device *dev,
-				      struct net *net, __be32 *saddr,
-				      const struct ip_tunnel_info *info,
-				      u8 protocol, bool use_cache);
-
 struct dst_entry *ipv4_blackhole_route(struct net *net,
 				       struct dst_entry *dst_orig);
 

include/net/udp_tunnel.h

@@ -162,6 +162,12 @@ int udp_tunnel6_xmit_skb(struct dst_entry *dst, struct sock *sk,
 
 void udp_tunnel_sock_release(struct socket *sock);
 
+struct rtable *udp_tunnel_dst_lookup(struct sk_buff *skb,
+				     struct net_device *dev,
+				     struct net *net, __be32 *saddr,
+				     const struct ip_tunnel_info *info,
+				     u8 protocol, bool use_cache);
+
 struct metadata_dst *udp_tun_rx_dst(struct sk_buff *skb, unsigned short family,
 				    __be16 flags, __be64 tunnel_id,
 				    int md_size);

net/ipv4/route.c

@@ -2885,54 +2885,6 @@ struct rtable *ip_route_output_flow(struct net *net, struct flowi4 *flp4,
 }
 EXPORT_SYMBOL_GPL(ip_route_output_flow);
 
-struct rtable *ip_route_output_tunnel(struct sk_buff *skb,
-				      struct net_device *dev,
-				      struct net *net, __be32 *saddr,
-				      const struct ip_tunnel_info *info,
-				      u8 protocol, bool use_cache)
-{
-#ifdef CONFIG_DST_CACHE
-	struct dst_cache *dst_cache;
-#endif
-	struct rtable *rt = NULL;
-	struct flowi4 fl4;
-	__u8 tos;
-
-#ifdef CONFIG_DST_CACHE
-	dst_cache = (struct dst_cache *)&info->dst_cache;
-	if (use_cache) {
-		rt = dst_cache_get_ip4(dst_cache, saddr);
-		if (rt)
-			return rt;
-	}
-#endif
-	memset(&fl4, 0, sizeof(fl4));
-	fl4.flowi4_mark = skb->mark;
-	fl4.flowi4_proto = protocol;
-	fl4.daddr = info->key.u.ipv4.dst;
-	fl4.saddr = info->key.u.ipv4.src;
-	tos = info->key.tos;
-	fl4.flowi4_tos = RT_TOS(tos);
-
-	rt = ip_route_output_key(net, &fl4);
-	if (IS_ERR(rt)) {
-		netdev_dbg(dev, "no route to %pI4\n", &fl4.daddr);
-		return ERR_PTR(-ENETUNREACH);
-	}
-	if (rt->dst.dev == dev) { /* is this necessary? */
-		netdev_dbg(dev, "circular route to %pI4\n", &fl4.daddr);
-		ip_rt_put(rt);
-		return ERR_PTR(-ELOOP);
-	}
-#ifdef CONFIG_DST_CACHE
-	if (use_cache)
-		dst_cache_set_ip4(dst_cache, &rt->dst, fl4.saddr);
-#endif
-	*saddr = fl4.saddr;
-	return rt;
-}
-EXPORT_SYMBOL_GPL(ip_route_output_tunnel);
-
 /* called with rcu_read_lock held */
 static int rt_fill_info(struct net *net, __be32 dst, __be32 src,
 			struct rtable *rt, u32 table_id, struct flowi4 *fl4,

net/ipv4/udp_tunnel_core.c

@@ -204,4 +204,52 @@ struct metadata_dst *udp_tun_rx_dst(struct sk_buff *skb,  unsigned short family,
 }
 EXPORT_SYMBOL_GPL(udp_tun_rx_dst);
 
+struct rtable *udp_tunnel_dst_lookup(struct sk_buff *skb,
+				     struct net_device *dev,
+				     struct net *net, __be32 *saddr,
+				     const struct ip_tunnel_info *info,
+				     u8 protocol, bool use_cache)
+{
+#ifdef CONFIG_DST_CACHE
+	struct dst_cache *dst_cache;
+#endif
+	struct rtable *rt = NULL;
+	struct flowi4 fl4;
+	__u8 tos;
+
+#ifdef CONFIG_DST_CACHE
+	dst_cache = (struct dst_cache *)&info->dst_cache;
+	if (use_cache) {
+		rt = dst_cache_get_ip4(dst_cache, saddr);
+		if (rt)
+			return rt;
+	}
+#endif
+	memset(&fl4, 0, sizeof(fl4));
+	fl4.flowi4_mark = skb->mark;
+	fl4.flowi4_proto = protocol;
+	fl4.daddr = info->key.u.ipv4.dst;
+	fl4.saddr = info->key.u.ipv4.src;
+	tos = info->key.tos;
+	fl4.flowi4_tos = RT_TOS(tos);
+
+	rt = ip_route_output_key(net, &fl4);
+	if (IS_ERR(rt)) {
+		netdev_dbg(dev, "no route to %pI4\n", &fl4.daddr);
+		return ERR_PTR(-ENETUNREACH);
+	}
+	if (rt->dst.dev == dev) { /* is this necessary? */
+		netdev_dbg(dev, "circular route to %pI4\n", &fl4.daddr);
+		ip_rt_put(rt);
+		return ERR_PTR(-ELOOP);
+	}
+#ifdef CONFIG_DST_CACHE
+	if (use_cache)
+		dst_cache_set_ip4(dst_cache, &rt->dst, fl4.saddr);
+#endif
+	*saddr = fl4.saddr;
+	return rt;
+}
+EXPORT_SYMBOL_GPL(udp_tunnel_dst_lookup);
+
 MODULE_LICENSE("GPL");