Subject: [PATCH net-next 1/8] UDP: introduce a udp_hashfn function

From: Pavel Emelyanov <[email-masked]>
Date: Mon, 16 Jun 2008 13:38:07 +0400

Currently the chain to store a UDP socket is calculated with
simple (x & (UDP_HTABLE_SIZE - 1)). But taking net into account
would make this calculation a bit more complex, so moving it into
a function would help.

Signed-off-by: Pavel Emelyanov <[email-masked]>

---
 include/linux/udp.h |    5 +++++
 net/ipv4/udp.c      |   12 ++++++------
 net/ipv6/udp.c      |    4 ++--
 3 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/include/linux/udp.h b/include/linux/udp.h
index 581ca2c..9c94312 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -46,6 +46,11 @@ static inline struct udphdr *udp_hdr(const struct sk_buff *skb)
 
 #define UDP_HTABLE_SIZE		128
 
+static inline int udp_hashfn(const unsigned 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 56fcda3..34818c2 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -136,7 +136,7 @@ static inline int __udp_lib_lport_inuse(struct net *net, __u16 num,
 	struct sock *sk;
 	struct hlist_node *node;
 
-	sk_for_each(sk, node, &udptable[num & (UDP_HTABLE_SIZE - 1)])
+	sk_for_each(sk, node, &udptable[udp_hashfn(num)])
 		if (net_eq(sock_net(sk), net) && sk->sk_hash == num)
 			return 1;
 	return 0;
@@ -176,7 +176,7 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
 		for (i = 0; i < UDP_HTABLE_SIZE; i++) {
 			int size = 0;
 
-			head = &udptable[rover & (UDP_HTABLE_SIZE - 1)];
+			head = &udptable[udp_hashfn(rover)];
 			if (hlist_empty(head))
 				goto gotit;
 
@@ -213,7 +213,7 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
 gotit:
 		snum = rover;
 	} else {
-		head = &udptable[snum & (UDP_HTABLE_SIZE - 1)];
+		head = &udptable[udp_hashfn(snum)];
 
 		sk_for_each(sk2, node, head)
 			if (sk2->sk_hash == snum                             &&
@@ -229,7 +229,7 @@ gotit:
 	inet_sk(sk)->num = snum;
 	sk->sk_hash = snum;
 	if (sk_unhashed(sk)) {
-		head = &udptable[snum & (UDP_HTABLE_SIZE - 1)];
+		head = &udptable[udp_hashfn(snum)];
 		sk_add_node(sk, head);
 		sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
 	}
@@ -266,7 +266,7 @@ static struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
 	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 (net_eq(sock_net(sk), net) && sk->sk_hash == hnum &&
@@ -1070,7 +1070,7 @@ static int __udp4_lib_mcast_deliver(struct sk_buff *skb,
 	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 = skb->dev->ifindex;
 	sk = udp_v4_mcast_next(sk, uh->dest, daddr, uh->source, saddr, dif);
 	if (sk) {
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index dd30962..61d3c99 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -67,7 +67,7 @@ static struct sock *__udp6_lib_lookup(struct net *net,
 	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 (net_eq(sock_net(sk), net) && sk->sk_hash == hnum &&
@@ -363,7 +363,7 @@ static int __udp6_lib_mcast_deliver(struct sk_buff *skb, struct in6_addr *saddr,
 	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) {
-- 
1.5.3.4