[PATCH] Consolidate udp hash calculations

[Pavel Emelianov <xemul@sw.ru>]

Make access to udphash/udplitehash symmetrical to inet hashes.

This may also help network namespaces, since they tend to use
one hash for different namespaces by selecting the hash chain
depending on a hash value and the namespace.

Signed-off-by: Pavel Emelianov <xemul@openvz.org>

---

diff --git a/include/linux/udp.h b/include/linux/udp.h
index 6de445c..a40ccd4 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -49,6 +49,11 @@ static inline struct udphdr *udp_hdr(con
 #include <net/inet_sock.h>
 #define UDP_HTABLE_SIZE		128
 
+static inline unsigned int udp_hashfn(unsigned int num)
+{
+	return num & (UDP_HTABLE_SIZE - 1);
+}
+
 struct udp_sock {
 	/* inet_sock has to be the first member */
 	struct inet_sock inet;
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 113e0c4..8ea1c81 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -132,7 +132,7 @@ static inline int __udp_lib_port_inuse(u
 	struct hlist_node *node;
 	struct inet_sock *inet;
 
-	sk_for_each(sk, node, &udptable[hash & (UDP_HTABLE_SIZE - 1)]) {
+	sk_for_each(sk, node, &udptable[udp_hashfn(hash)]) {
 		if (sk->sk_hash != hash)
 			continue;
 		inet = inet_sk(sk);
@@ -159,7 +159,6 @@ int __udp_lib_get_port(struct sock *sk, 
 					 const struct sock *sk2 )    )
 {
 	struct hlist_node *node;
-	struct hlist_head *head;
 	struct sock *sk2;
 	unsigned int hash;
 	int    error = 1;
@@ -175,10 +174,11 @@ int __udp_lib_get_port(struct sock *sk, 
 		best = result = *port_rover;
 		for (i = 0; i < UDP_HTABLE_SIZE; i++, result++) {
 			int size;
+			struct hlist_head *head;
 
 			hash = hash_port_and_addr(result,
 					inet_sk(sk)->rcv_saddr);
-			head = &udptable[hash & (UDP_HTABLE_SIZE - 1)];
+			head = &udptable[udp_hashfn(hash)];
 			if (hlist_empty(head)) {
 				if (result > sysctl_local_port_range[1])
 					result = sysctl_local_port_range[0] +
@@ -222,9 +222,7 @@ gotit:
 		*port_rover = snum = result;
 	} else {
 		hash = hash_port_and_addr(snum, 0);
-		head = &udptable[hash & (UDP_HTABLE_SIZE - 1)];
-
-		sk_for_each(sk2, node, head)
+		sk_for_each(sk2, node, &udptable[udp_hashfn(hash)])
 			if (sk2->sk_hash == hash &&
 			    sk2 != sk &&
 			    inet_sk(sk2)->num == snum &&
@@ -237,9 +235,7 @@ gotit:
 		if (inet_sk(sk)->rcv_saddr) {
 			hash = hash_port_and_addr(snum,
 						  inet_sk(sk)->rcv_saddr);
-			head = &udptable[hash & (UDP_HTABLE_SIZE - 1)];
-
-			sk_for_each(sk2, node, head)
+			sk_for_each(sk2, node, &udptable[udp_hashfn(hash)])
 				if (sk2->sk_hash == hash &&
 				    sk2 != sk &&
 				    inet_sk(sk2)->num == snum &&
@@ -255,8 +251,7 @@ gotit:
 	inet_sk(sk)->num = snum;
 	sk->sk_hash = hash;
 	if (sk_unhashed(sk)) {
-		head = &udptable[hash & (UDP_HTABLE_SIZE - 1)];
-		sk_add_node(sk, head);
+		sk_add_node(sk, &udptable[udp_hashfn(hash)]);
 		sock_prot_inc_use(sk->sk_prot);
 	}
 	error = 0;
@@ -304,7 +299,7 @@ static struct sock *__udp4_lib_lookup(__
 
 lookup:
 
-	sk_for_each(sk, node, &udptable[hash & (UDP_HTABLE_SIZE - 1)]) {
+	sk_for_each(sk, node, &udptable[udp_hashfn(hash)]) {
 		struct inet_sock *inet = inet_sk(sk);
 
 		if (sk->sk_hash != hash || ipv6_only_sock(sk) ||
@@ -1205,8 +1200,8 @@ static int __udp4_lib_mcast_deliver(stru
 
 	read_lock(&udp_hash_lock);
 
-	sk = sk_head(&udptable[hash & (UDP_HTABLE_SIZE - 1)]);
-	skw = sk_head(&udptable[hashwild & (UDP_HTABLE_SIZE - 1)]);
+	sk = sk_head(&udptable[udp_hashfn(hash)]);
+	skw = sk_head(&udptable[udp_hashfn(hashwild)]);
 
 	sk = udp_v4_mcast_next(sk, hash, hport, daddr, uh->source, saddr, dif);
 	if (!sk) {
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index b083c09..a0a8915 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -67,7 +67,7 @@ static struct sock *__udp6_lib_lookup(st
 	int badness = -1;
 
 	read_lock(&udp_hash_lock);
-	sk_for_each(sk, node, &udptable[hnum & (UDP_HTABLE_SIZE - 1)]) {
+	sk_for_each(sk, node, &udptable[udp_hashfn(hnum)]) {
 		struct inet_sock *inet = inet_sk(sk);
 
 		if (sk->sk_hash == hnum && sk->sk_family == PF_INET6) {
@@ -350,7 +350,7 @@ static int __udp6_lib_mcast_deliver(stru
 	int dif;
 
 	read_lock(&udp_hash_lock);
-	sk = sk_head(&udptable[ntohs(uh->dest) & (UDP_HTABLE_SIZE - 1)]);
+	sk = sk_head(&udptable[udp_hashfn(ntohs(uh->dest))]);
 	dif = inet6_iif(skb);
 	sk = udp_v6_mcast_next(sk, uh->dest, daddr, uh->source, saddr, dif);
 	if (!sk) {