gtp: add dst_cache to tunnels

Destination caching on a per-tunnel basis is a performance win, so we
enable this unconditionally for the module.

Signed-off-by: Jonas Bonn <jonas@norrbonn.se>

drivers/net/Kconfig

@@ -276,6 +276,7 @@ config GTP
 	tristate "GPRS Tunneling Protocol datapath (GTP-U)"
 	depends on INET
 	select NET_UDP_TUNNEL
+	select DST_CACHE
 	help
 	  This allows one to create gtp virtual interfaces that provide
 	  the GPRS Tunneling Protocol datapath (GTP-U). This tunneling protocol

drivers/net/gtp.c

@@ -64,6 +64,8 @@ struct pdp_ctx {
 	struct sock		*sk;
 	struct net_device       *dev;
 
+	struct dst_cache dst_cache;
+
 	atomic_t		tx_seq;
 	struct rcu_head		rcu_head;
 };
@@ -577,9 +579,15 @@ static struct rtable *gtp_get_v4_rt(struct sk_buff *skb,
 				    __be32 *saddr)
 {
 	const struct sock *sk = pctx->sk;
+	struct dst_cache *dst_cache;
 	struct rtable *rt = NULL;
 	struct flowi4 fl4;
 
+	dst_cache = (struct dst_cache *)&pctx->dst_cache;
+	rt = dst_cache_get_ip4(dst_cache, saddr);
+	if (rt)
+		return rt;
+
 	memset(&fl4, 0, sizeof(fl4));
 	fl4.flowi4_oif		= sk->sk_bound_dev_if;
 	fl4.daddr		= ipv4(&pctx->peer_addr);
@@ -600,6 +608,8 @@ static struct rtable *gtp_get_v4_rt(struct sk_buff *skb,
 
 	*saddr = fl4.saddr;
 
+	dst_cache_set_ip4(dst_cache, &rt->dst, *saddr);
+
 	return rt;
 }
 
@@ -610,8 +620,14 @@ static struct dst_entry *gtp_get_v6_dst(struct sk_buff *skb,
 {
 	const struct sock *sk = pctx->sk;
 	struct dst_entry *dst = NULL;
+	struct dst_cache *dst_cache;
 	struct flowi6 fl6;
 
+	dst_cache = (struct dst_cache *)&pctx->dst_cache;
+	dst = dst_cache_get_ip6(dst_cache, saddr);
+	if (dst)
+		return dst;
+
 	memset(&fl6, 0, sizeof(fl6));
 	fl6.flowi6_mark = skb->mark;
 	fl6.flowi6_proto = IPPROTO_UDP;
@@ -630,6 +646,8 @@ static struct dst_entry *gtp_get_v6_dst(struct sk_buff *skb,
 
 	*saddr = fl6.saddr;
 
+	dst_cache_set_ip6(dst_cache, dst, saddr);
+
 	return dst;
 }
 
@@ -1236,6 +1254,8 @@ static void pdp_fill(struct pdp_ctx *pctx, struct genl_info *info)
 	pctx->gtp_version = nla_get_u32(info->attrs[GTPA_VERSION]);
 	pctx->flags = 0;
 
+	dst_cache_reset(&pctx->dst_cache);
+
 	if (info->attrs[GTPA_PEER_IPV6]) {
 		pctx->flags |= PDP_F_PEER_V6;
 		pctx->peer_addr = nla_get_in6_addr(info->attrs[GTPA_PEER_IPV6]);
@@ -1331,6 +1351,11 @@ static struct pdp_ctx *gtp_pdp_add(struct gtp_dev *gtp, struct sock *sk,
 	if (pctx == NULL)
 		return ERR_PTR(-ENOMEM);
 
+	if (dst_cache_init(&pctx->dst_cache, GFP_ATOMIC)) {
+		kfree(pctx);
+		return ERR_PTR(-ENOBUFS);
+	}
+
 	sock_hold(sk);
 	pctx->sk = sk;
 	pctx->dev = gtp->dev;
@@ -1374,6 +1399,8 @@ static void pdp_context_free(struct rcu_head *head)
 {
 	struct pdp_ctx *pctx = container_of(head, struct pdp_ctx, rcu_head);
 
+	dst_cache_destroy(&pctx->dst_cache);
+
 	sock_put(pctx->sk);
 	kfree(pctx);
 }