tipc: add dst_cache support for udp media

As other udp/ip tunnels do, tipc udp media should also have a
lockless dst_cache supported on its tx path.

Here we add dst_cache into udp_replicast to support dst cache
for both rmcast and rcast, and rmcast uses ub->rcast and each
rcast uses its own node in ub->rcast.list.
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/tipc/udp_media.c

@@ -76,6 +76,7 @@ struct udp_media_addr {
 /* struct udp_replicast - container for UDP remote addresses */
 struct udp_replicast {
 	struct udp_media_addr addr;
+	struct dst_cache dst_cache;
 	struct rcu_head rcu;
 	struct list_head list;
 };
@@ -158,12 +159,15 @@ static int tipc_udp_addr2msg(char *msg, struct tipc_media_addr *a)
 /* tipc_send_msg - enqueue a send request */
 static int tipc_udp_xmit(struct net *net, struct sk_buff *skb,
 			 struct udp_bearer *ub, struct udp_media_addr *src,
-			 struct udp_media_addr *dst)
+			 struct udp_media_addr *dst, struct dst_cache *cache)
 {
+	struct dst_entry *ndst = dst_cache_get(cache);
 	int ttl, err = 0;
-	struct rtable *rt;
 
 	if (dst->proto == htons(ETH_P_IP)) {
+		struct rtable *rt = (struct rtable *)ndst;
+
+		if (!rt) {
 			struct flowi4 fl = {
 				.daddr = dst->ipv4.s_addr,
 				.saddr = src->ipv4.s_addr,
@@ -175,6 +179,8 @@ static int tipc_udp_xmit(struct net *net, struct sk_buff *skb,
 				err = PTR_ERR(rt);
 				goto tx_error;
 			}
+			dst_cache_set_ip4(cache, &rt->dst, fl.saddr);
+		}
 
 		ttl = ip4_dst_hoplimit(&rt->dst);
 		udp_tunnel_xmit_skb(rt, ub->ubsock->sk, skb, src->ipv4.s_addr,
@@ -182,17 +188,19 @@ static int tipc_udp_xmit(struct net *net, struct sk_buff *skb,
 				    dst->port, false, true);
 #if IS_ENABLED(CONFIG_IPV6)
 	} else {
-		struct dst_entry *ndst;
+		if (!ndst) {
 			struct flowi6 fl6 = {
 				.flowi6_oif = ub->ifindex,
 				.daddr = dst->ipv6,
 				.saddr = src->ipv6,
 				.flowi6_proto = IPPROTO_UDP
 			};
-		err = ipv6_stub->ipv6_dst_lookup(net, ub->ubsock->sk, &ndst,
-						 &fl6);
+			err = ipv6_stub->ipv6_dst_lookup(net, ub->ubsock->sk,
+							 &ndst, &fl6);
 			if (err)
 				goto tx_error;
+			dst_cache_set_ip6(cache, ndst, &fl6.saddr);
+		}
 		ttl = ip6_dst_hoplimit(ndst);
 		err = udp_tunnel6_xmit_skb(ndst, ub->ubsock->sk, skb, NULL,
 					   &src->ipv6, &dst->ipv6, 0, ttl, 0,
@@ -230,7 +238,8 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
 	}
 
 	if (addr->broadcast != TIPC_REPLICAST_SUPPORT)
-		return tipc_udp_xmit(net, skb, ub, src, dst);
+		return tipc_udp_xmit(net, skb, ub, src, dst,
+				     &ub->rcast.dst_cache);
 
 	/* Replicast, send an skb to each configured IP address */
 	list_for_each_entry_rcu(rcast, &ub->rcast.list, list) {
@@ -242,7 +251,8 @@ static int tipc_udp_send_msg(struct net *net, struct sk_buff *skb,
 			goto out;
 		}
 
-		err = tipc_udp_xmit(net, _skb, ub, src, &rcast->addr);
+		err = tipc_udp_xmit(net, _skb, ub, src, &rcast->addr,
+				    &rcast->dst_cache);
 		if (err)
 			goto out;
 	}
@@ -286,6 +296,11 @@ static int tipc_udp_rcast_add(struct tipc_bearer *b,
 	if (!rcast)
 		return -ENOMEM;
 
+	if (dst_cache_init(&rcast->dst_cache, GFP_ATOMIC)) {
+		kfree(rcast);
+		return -ENOMEM;
+	}
+
 	memcpy(&rcast->addr, addr, sizeof(struct udp_media_addr));
 
 	if (ntohs(addr->proto) == ETH_P_IP)
@@ -742,6 +757,10 @@ static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
 	tuncfg.encap_destroy = NULL;
 	setup_udp_tunnel_sock(net, ub->ubsock, &tuncfg);
 
+	err = dst_cache_init(&ub->rcast.dst_cache, GFP_ATOMIC);
+	if (err)
+		goto err;
+
 	/**
 	 * The bcast media address port is used for all peers and the ip
 	 * is used if it's a multicast address.
@@ -756,6 +775,7 @@ static int tipc_udp_enable(struct net *net, struct tipc_bearer *b,
 
 	return 0;
 err:
+	dst_cache_destroy(&ub->rcast.dst_cache);
 	if (ub->ubsock)
 		udp_tunnel_sock_release(ub->ubsock);
 	kfree(ub);
@@ -769,10 +789,12 @@ static void cleanup_bearer(struct work_struct *work)
 	struct udp_replicast *rcast, *tmp;
 
 	list_for_each_entry_safe(rcast, tmp, &ub->rcast.list, list) {
+		dst_cache_destroy(&rcast->dst_cache);
 		list_del_rcu(&rcast->list);
 		kfree_rcu(rcast, rcu);
 	}
 
+	dst_cache_destroy(&ub->rcast.dst_cache);
 	if (ub->ubsock)
 		udp_tunnel_sock_release(ub->ubsock);
 	synchronize_net();