[INET]: Generalise tcp_v4_lookup_listener

[acme@toy net-2.6.14]$ grep built-in /tmp/before /tmp/after
/tmp/before: 282560       13122    9312  304994   4a762 net/ipv4/built-in.o
/tmp/after:  282560       13122    9312  304994   4a762 net/ipv4/built-in.o

Will be used in DCCP, not exporting it right now not to get in Adrian
Bunk's exported-but-not-used-on-modules radar 8)

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_hashtables.h

@@ -16,8 +16,10 @@
 
 #include <linux/interrupt.h>
 #include <linux/ip.h>
+#include <linux/ipv6.h>
 #include <linux/list.h>
 #include <linux/slab.h>
+#include <linux/socket.h>
 #include <linux/spinlock.h>
 #include <linux/types.h>
 #include <linux/wait.h>
@@ -274,4 +276,38 @@ out:
 	if (sk->sk_state == TCP_LISTEN)
 		wake_up(&hashinfo->lhash_wait);
 }
+
+extern struct sock *__inet_lookup_listener(const struct hlist_head *head,
+					   const u32 daddr,
+					   const unsigned short hnum,
+					   const int dif);
+
+/* Optimize the common listener case. */
+static inline struct sock *inet_lookup_listener(struct inet_hashinfo *hashinfo,
+						const u32 daddr,
+						const unsigned short hnum,
+						const int dif)
+{
+	struct sock *sk = NULL;
+	struct hlist_head *head;
+
+	read_lock(&hashinfo->lhash_lock);
+	head = &hashinfo->listening_hash[inet_lhashfn(hnum)];
+	if (!hlist_empty(head)) {
+		const struct inet_sock *inet = inet_sk((sk = __sk_head(head)));
+
+		if (inet->num == hnum && !sk->sk_node.next &&
+		    (!inet->rcv_saddr || inet->rcv_saddr == daddr) &&
+		    (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) &&
+		    !sk->sk_bound_dev_if)
+			goto sherry_cache;
+		sk = __inet_lookup_listener(head, daddr, hnum, dif);
+	}
+	if (sk) {
+sherry_cache:
+		sock_hold(sk);
+	}
+	read_unlock(&hashinfo->lhash_lock);
+	return sk;
+}
 #endif /* _INET_HASHTABLES_H */

net/ipv4/inet_hashtables.c

@@ -121,3 +121,44 @@ void inet_listen_wlock(struct inet_hashinfo *hashinfo)
 }
 
 EXPORT_SYMBOL(inet_listen_wlock);
+
+/*
+ * Don't inline this cruft. Here are some nice properties to exploit here. The
+ * BSD API does not allow a listening sock to specify the remote port nor the
+ * remote address for the connection. So always assume those are both
+ * wildcarded during the search since they can never be otherwise.
+ */
+struct sock *__inet_lookup_listener(const struct hlist_head *head, const u32 daddr,
+				    const unsigned short hnum, const int dif)
+{
+	struct sock *result = NULL, *sk;
+	const struct hlist_node *node;
+	int hiscore = -1;
+
+	sk_for_each(sk, node, head) {
+		const struct inet_sock *inet = inet_sk(sk);
+
+		if (inet->num == hnum && !ipv6_only_sock(sk)) {
+			const __u32 rcv_saddr = inet->rcv_saddr;
+			int score = sk->sk_family == PF_INET ? 1 : 0;
+
+			if (rcv_saddr) {
+				if (rcv_saddr != daddr)
+					continue;
+				score += 2;
+			}
+			if (sk->sk_bound_dev_if) {
+				if (sk->sk_bound_dev_if != dif)
+					continue;
+				score += 2;
+			}
+			if (score == 5)
+				return sk;
+			if (score > hiscore) {
+				hiscore	= score;
+				result	= sk;
+			}
+		}
+	}
+	return result;
+}

net/ipv4/tcp_ipv4.c

@@ -238,78 +238,6 @@ void tcp_unhash(struct sock *sk)
 	inet_unhash(&tcp_hashinfo, sk);
 }
 
-/* Don't inline this cruft.  Here are some nice properties to
- * exploit here.  The BSD API does not allow a listening TCP
- * to specify the remote port nor the remote address for the
- * connection.  So always assume those are both wildcarded
- * during the search since they can never be otherwise.
- */
-static struct sock *__tcp_v4_lookup_listener(struct hlist_head *head,
-					     const u32 daddr,
-					     const unsigned short hnum,
-					     const int dif)
-{
-	struct sock *result = NULL, *sk;
-	struct hlist_node *node;
-	int score, hiscore;
-
-	hiscore=-1;
-	sk_for_each(sk, node, head) {
-		struct inet_sock *inet = inet_sk(sk);
-
-		if (inet->num == hnum && !ipv6_only_sock(sk)) {
-			__u32 rcv_saddr = inet->rcv_saddr;
-
-			score = (sk->sk_family == PF_INET ? 1 : 0);
-			if (rcv_saddr) {
-				if (rcv_saddr != daddr)
-					continue;
-				score+=2;
-			}
-			if (sk->sk_bound_dev_if) {
-				if (sk->sk_bound_dev_if != dif)
-					continue;
-				score+=2;
-			}
-			if (score == 5)
-				return sk;
-			if (score > hiscore) {
-				hiscore = score;
-				result = sk;
-			}
-		}
-	}
-	return result;
-}
-
-/* Optimize the common listener case. */
-static inline struct sock *tcp_v4_lookup_listener(const u32 daddr,
-						  const unsigned short hnum,
-						  const int dif)
-{
-	struct sock *sk = NULL;
-	struct hlist_head *head;
-
-	read_lock(&tcp_hashinfo.lhash_lock);
-	head = &tcp_hashinfo.listening_hash[inet_lhashfn(hnum)];
-	if (!hlist_empty(head)) {
-		struct inet_sock *inet = inet_sk((sk = __sk_head(head)));
-
-		if (inet->num == hnum && !sk->sk_node.next &&
-		    (!inet->rcv_saddr || inet->rcv_saddr == daddr) &&
-		    (sk->sk_family == PF_INET || !ipv6_only_sock(sk)) &&
-		    !sk->sk_bound_dev_if)
-			goto sherry_cache;
-		sk = __tcp_v4_lookup_listener(head, daddr, hnum, dif);
-	}
-	if (sk) {
-sherry_cache:
-		sock_hold(sk);
-	}
-	read_unlock(&tcp_hashinfo.lhash_lock);
-	return sk;
-}
-
 /* Sockets in TCP_CLOSE state are _always_ taken out of the hash, so
  * we need not check it for TCP lookups anymore, thanks Alexey. -DaveM
  *
@@ -358,7 +286,7 @@ static inline struct sock *__tcp_v4_lookup(u32 saddr, u16 sport,
 	struct sock *sk = __tcp_v4_lookup_established(saddr, sport,
 						      daddr, hnum, dif);
 
-	return sk ? : tcp_v4_lookup_listener(daddr, hnum, dif);
+	return sk ? : inet_lookup_listener(&tcp_hashinfo, daddr, hnum, dif);
 }
 
 inline struct sock *tcp_v4_lookup(u32 saddr, u16 sport, u32 daddr,
@@ -1641,7 +1569,8 @@ do_time_wait:
 	switch (tcp_timewait_state_process((struct tcp_tw_bucket *)sk,
 					   skb, th, skb->len)) {
 	case TCP_TW_SYN: {
-		struct sock *sk2 = tcp_v4_lookup_listener(skb->nh.iph->daddr,
+		struct sock *sk2 = inet_lookup_listener(&tcp_hashinfo,
+							skb->nh.iph->daddr,
 							ntohs(th->dest),
 							tcp_v4_iif(skb));
 		if (sk2) {