ip_tunnel: Add dst_cache support in lwtunnel_state of ip tunnel

The lwtunnel_state is not init the dst_cache Which make the
ip_md_tunnel_xmit can't use the dst_cache. It will lookup
route table every packets.
Signed-off-by: wenxu <wenxu@ucloud.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/core/lwtunnel.c

@@ -122,18 +122,18 @@ int lwtunnel_build_state(u16 encap_type,
 	ret = -EOPNOTSUPP;
 	rcu_read_lock();
 	ops = rcu_dereference(lwtun_encaps[encap_type]);
-	if (likely(ops && ops->build_state && try_module_get(ops->owner))) {
+	if (likely(ops && ops->build_state && try_module_get(ops->owner)))
 		found = true;
+	rcu_read_unlock();
+
+	if (found) {
 		ret = ops->build_state(encap, family, cfg, lws, extack);
 		if (ret)
 			module_put(ops->owner);
-	}
-	rcu_read_unlock();
-
-	/* don't rely on -EOPNOTSUPP to detect match as build_state
-	 * handlers could return it
-	 */
-	if (!found) {
+	} else {
+		/* don't rely on -EOPNOTSUPP to detect match as build_state
+		 * handlers could return it
+		 */
 		NL_SET_ERR_MSG_ATTR(extack, encap,
 				    "LWT encapsulation type not supported");
 	}

net/ipv4/ip_tunnel_core.c

@@ -252,6 +252,14 @@ static int ip_tun_build_state(struct nlattr *attr,
 
 	tun_info = lwt_tun_info(new_state);
 
+#ifdef CONFIG_DST_CACHE
+	err = dst_cache_init(&tun_info->dst_cache, GFP_KERNEL);
+	if (err) {
+		lwtstate_free(new_state);
+		return err;
+	}
+#endif
+
 	if (tb[LWTUNNEL_IP_ID])
 		tun_info->key.tun_id = nla_get_be64(tb[LWTUNNEL_IP_ID]);
 
@@ -278,6 +286,15 @@ static int ip_tun_build_state(struct nlattr *attr,
 	return 0;
 }
 
+static void ip_tun_destroy_state(struct lwtunnel_state *lwtstate)
+{
+#ifdef CONFIG_DST_CACHE
+	struct ip_tunnel_info *tun_info = lwt_tun_info(lwtstate);
+
+	dst_cache_destroy(&tun_info->dst_cache);
+#endif
+}
+
 static int ip_tun_fill_encap_info(struct sk_buff *skb,
 				  struct lwtunnel_state *lwtstate)
 {
@@ -313,6 +330,7 @@ static int ip_tun_cmp_encap(struct lwtunnel_state *a, struct lwtunnel_state *b)
 
 static const struct lwtunnel_encap_ops ip_tun_lwt_ops = {
 	.build_state = ip_tun_build_state,
+	.destroy_state = ip_tun_destroy_state,
 	.fill_encap = ip_tun_fill_encap_info,
 	.get_encap_size = ip_tun_encap_nlsize,
 	.cmp_encap = ip_tun_cmp_encap,