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udp: Use hlist_nulls in UDP RCU code

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This is a straightforward patch, using hlist_nulls infrastructure.

RCUification already done on UDP two weeks ago.

Using hlist_nulls permits us to avoid some memory barriers, both
at lookup time and delete time.

Patch is large because it adds new macros to include/net/sock.h.
These macros will be used by TCP & DCCP in next patch.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2008-11-16 19:39:21 -08:00
committed by David S. Miller
parent bbaffaca48
commit 88ab1932ea
5 changed files with 83 additions and 66 deletions
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26
net/ipv6/udp.c
View File

@@ -98,7 +98,7 @@ static struct sock *__udp6_lib_lookup(struct net *net,
int dif, struct udp_table *udptable)
{
struct sock *sk, *result;
struct hlist_node *node, *next;
struct hlist_nulls_node *node;
unsigned short hnum = ntohs(dport);
unsigned int hash = udp_hashfn(net, hnum);
struct udp_hslot *hslot = &udptable->hash[hash];
@@ -108,19 +108,21 @@ static struct sock *__udp6_lib_lookup(struct net *net,
begin:
result = NULL;
badness = -1;
sk_for_each_rcu_safenext(sk, node, &hslot->head, next) {
/*
* lockless reader, and SLAB_DESTROY_BY_RCU items:
* We must check this item was not moved to another chain
*/
if (udp_hashfn(net, sk->sk_hash) != hash)
goto begin;
sk_nulls_for_each_rcu(sk, node, &hslot->head) {
score = compute_score(sk, net, hnum, saddr, sport, daddr, dport, dif);
if (score > badness) {
result = sk;
badness = score;
}
}
/*
* if the nulls value we got at the end of this lookup is
* not the expected one, we must restart lookup.
* We probably met an item that was moved to another chain.
*/
if (get_nulls_value(node) != hash)
goto begin;
if (result) {
if (unlikely(!atomic_inc_not_zero(&result->sk_refcnt)))
result = NULL;
@@ -374,11 +376,11 @@ static struct sock *udp_v6_mcast_next(struct net *net, struct sock *sk,
__be16 rmt_port, struct in6_addr *rmt_addr,
int dif)
{
struct hlist_node *node;
struct hlist_nulls_node *node;
struct sock *s = sk;
unsigned short num = ntohs(loc_port);
sk_for_each_from(s, node) {
sk_nulls_for_each_from(s, node) {
struct inet_sock *inet = inet_sk(s);
if (!net_eq(sock_net(s), net))
@@ -423,7 +425,7 @@ static int __udp6_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
int dif;
spin_lock(&hslot->lock);
sk = sk_head(&hslot->head);
sk = sk_nulls_head(&hslot->head);
dif = inet6_iif(skb);
sk = udp_v6_mcast_next(net, sk, uh->dest, daddr, uh->source, saddr, dif);
if (!sk) {
@@ -432,7 +434,7 @@ static int __udp6_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
}
sk2 = sk;
while ((sk2 = udp_v6_mcast_next(net, sk_next(sk2), uh->dest, daddr,
while ((sk2 = udp_v6_mcast_next(net, sk_nulls_next(sk2), uh->dest, daddr,
uh->source, saddr, dif))) {
struct sk_buff *buff = skb_clone(skb, GFP_ATOMIC);
if (buff) {