[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>

1 files changed, 36 insertions, 0 deletions

diff --git a/include/net/inet_hashtables.h b/include/net/inet_hashtables.h
index 6731df2cea67..1c4fa0065a8e 100644
--- a/include/net/inet_hashtables.h
+++ b/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 */