[INET]: Move the TCP ehash functions to include/net/inet_hashtables.h

To be shared with DCCP (and others), this is the start of a series of patches
that will expose the already generic TCP hash table routines.

The few changes noticed when calling gcc -S before/after on a pentium4 were of
this type:

        movl    40(%esp), %edx
        cmpl    %esi, 472(%edx)
        je      .L168
-       pushl   $291
+       pushl   $272
        pushl   $.LC0
        pushl   $.LC1
        pushl   $.LC2

[acme@toy net-2.6.14]$ size net/ipv4/tcp_ipv4.before.o net/ipv4/tcp_ipv4.after.o
   text    data     bss     dec     hex filename
  17804     516     140   18460    481c net/ipv4/tcp_ipv4.before.o
  17804     516     140   18460    481c net/ipv4/tcp_ipv4.after.o

Holler if some weird architecture has issues with things like this 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

@@ -0,0 +1,40 @@
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ * Authors:	Lotsa people, from code originally in tcp
+ *
+ *	This program is free software; you can redistribute it and/or
+ *      modify it under the terms of the GNU General Public License
+ *      as published by the Free Software Foundation; either version
+ *      2 of the License, or (at your option) any later version.
+ */
+
+#ifndef _INET_HASHTABLES_H
+#define _INET_HASHTABLES_H
+
+#include <linux/types.h>
+
+static inline int inet_ehashfn(const __u32 laddr, const __u16 lport,
+			       const __u32 faddr, const __u16 fport,
+			       const int ehash_size)
+{
+	int h = (laddr ^ lport) ^ (faddr ^ fport);
+	h ^= h >> 16;
+	h ^= h >> 8;
+	return h & (ehash_size - 1);
+}
+
+static inline int inet_sk_ehashfn(const struct sock *sk, const int ehash_size)
+{
+	const struct inet_sock *inet = inet_sk(sk);
+	const __u32 laddr = inet->rcv_saddr;
+	const __u16 lport = inet->num;
+	const __u32 faddr = inet->daddr;
+	const __u16 fport = inet->dport;
+
+	return inet_ehashfn(laddr, lport, faddr, fport, ehash_size);
+}
+
+#endif /* _INET_HASHTABLES_H */

net/ipv4/tcp_ipv4.c

@@ -64,6 +64,7 @@
 #include <linux/times.h>
 
 #include <net/icmp.h>
+#include <net/inet_hashtables.h>
 #include <net/tcp.h>
 #include <net/ipv6.h>
 #include <net/inet_common.h>
@@ -104,26 +105,6 @@ struct tcp_hashinfo __cacheline_aligned tcp_hashinfo = {
 int sysctl_local_port_range[2] = { 1024, 4999 };
 int tcp_port_rover = 1024 - 1;
 
-static __inline__ int tcp_hashfn(__u32 laddr, __u16 lport,
-				 __u32 faddr, __u16 fport)
-{
-	int h = (laddr ^ lport) ^ (faddr ^ fport);
-	h ^= h >> 16;
-	h ^= h >> 8;
-	return h & (tcp_ehash_size - 1);
-}
-
-static __inline__ int tcp_sk_hashfn(struct sock *sk)
-{
-	struct inet_sock *inet = inet_sk(sk);
-	__u32 laddr = inet->rcv_saddr;
-	__u16 lport = inet->num;
-	__u32 faddr = inet->daddr;
-	__u16 fport = inet->dport;
-
-	return tcp_hashfn(laddr, lport, faddr, fport);
-}
-
 /* Allocate and initialize a new TCP local port bind bucket.
  * The bindhash mutex for snum's hash chain must be held here.
  */
@@ -367,7 +348,8 @@ static __inline__ void __tcp_v4_hash(struct sock *sk, const int listen_possible)
 		lock = &tcp_lhash_lock;
 		tcp_listen_wlock();
 	} else {
-		list = &tcp_ehash[(sk->sk_hashent = tcp_sk_hashfn(sk))].chain;
+		sk->sk_hashent = inet_sk_ehashfn(sk, tcp_ehash_size);
+		list = &tcp_ehash[sk->sk_hashent].chain;
 		lock = &tcp_ehash[sk->sk_hashent].lock;
 		write_lock(lock);
 	}
@@ -500,7 +482,7 @@ static inline struct sock *__tcp_v4_lookup_established(u32 saddr, u16 sport,
 	/* Optimize here for direct hit, only listening connections can
 	 * have wildcards anyways.
 	 */
-	int hash = tcp_hashfn(daddr, hnum, saddr, sport);
+	const int hash = inet_ehashfn(daddr, hnum, saddr, sport, tcp_ehash_size);
 	head = &tcp_ehash[hash];
 	read_lock(&head->lock);
 	sk_for_each(sk, node, &head->chain) {
@@ -563,7 +545,7 @@ static int __tcp_v4_check_established(struct sock *sk, __u16 lport,
 	int dif = sk->sk_bound_dev_if;
 	TCP_V4_ADDR_COOKIE(acookie, saddr, daddr)
 	__u32 ports = TCP_COMBINED_PORTS(inet->dport, lport);
-	int hash = tcp_hashfn(daddr, lport, saddr, inet->dport);
+	const int hash = inet_ehashfn(daddr, lport, saddr, inet->dport, tcp_ehash_size);
 	struct tcp_ehash_bucket *head = &tcp_ehash[hash];
 	struct sock *sk2;
 	struct hlist_node *node;