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authorEric Dumazet <dada1@cosmosbay.com>2008-11-16 19:39:21 -0800
committerDavid S. Miller <davem@davemloft.net>2008-11-16 19:39:21 -0800
commit88ab1932eac721c6e7336708558fa5ed02c85c80 (patch)
treec8788a1e3de08100bca341fa4180adfe5d02880f /net/ipv4
parentbbaffaca4810de1a25e32ecaf836eeaacc7a3d11 (diff)
udp: Use hlist_nulls in UDP RCU code
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>
Diffstat (limited to 'net/ipv4')
-rw-r--r--net/ipv4/udp.c47
1 files changed, 22 insertions, 25 deletions
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 54badc9a019..fea2d873dd4 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -127,9 +127,9 @@ static int udp_lib_lport_inuse(struct net *net, __u16 num,
const struct sock *sk2))
{
struct sock *sk2;
- struct hlist_node *node;
+ struct hlist_nulls_node *node;
- sk_for_each(sk2, node, &hslot->head)
+ sk_nulls_for_each(sk2, node, &hslot->head)
if (net_eq(sock_net(sk2), net) &&
sk2 != sk &&
sk2->sk_hash == num &&
@@ -189,12 +189,7 @@ int udp_lib_get_port(struct sock *sk, unsigned short snum,
inet_sk(sk)->num = snum;
sk->sk_hash = snum;
if (sk_unhashed(sk)) {
- /*
- * We need that previous write to sk->sk_hash committed
- * before write to sk->next done in following add_node() variant
- */
- smp_wmb();
- sk_add_node_rcu(sk, &hslot->head);
+ sk_nulls_add_node_rcu(sk, &hslot->head);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
}
error = 0;
@@ -261,7 +256,7 @@ static struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
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];
@@ -271,13 +266,7 @@ static struct sock *__udp4_lib_lookup(struct net *net, __be32 saddr,
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, saddr, hnum, sport,
daddr, dport, dif);
if (score > badness) {
@@ -285,6 +274,14 @@ begin:
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;
@@ -325,11 +322,11 @@ static inline struct sock *udp_v4_mcast_next(struct net *net, struct sock *sk,
__be16 rmt_port, __be32 rmt_addr,
int dif)
{
- struct hlist_node *node;
+ struct hlist_nulls_node *node;
struct sock *s = sk;
unsigned short hnum = 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) ||
@@ -977,7 +974,7 @@ void udp_lib_unhash(struct sock *sk)
struct udp_hslot *hslot = &udptable->hash[hash];
spin_lock_bh(&hslot->lock);
- if (sk_del_node_init_rcu(sk)) {
+ if (sk_nulls_del_node_init_rcu(sk)) {
inet_sk(sk)->num = 0;
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
}
@@ -1130,7 +1127,7 @@ static int __udp4_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 = skb->dev->ifindex;
sk = udp_v4_mcast_next(net, sk, uh->dest, daddr, uh->source, saddr, dif);
if (sk) {
@@ -1139,7 +1136,7 @@ static int __udp4_lib_mcast_deliver(struct net *net, struct sk_buff *skb,
do {
struct sk_buff *skb1 = skb;
- sknext = udp_v4_mcast_next(net, sk_next(sk), uh->dest,
+ sknext = udp_v4_mcast_next(net, sk_nulls_next(sk), uh->dest,
daddr, uh->source, saddr,
dif);
if (sknext)
@@ -1560,10 +1557,10 @@ static struct sock *udp_get_first(struct seq_file *seq, int start)
struct net *net = seq_file_net(seq);
for (state->bucket = start; state->bucket < UDP_HTABLE_SIZE; ++state->bucket) {
- struct hlist_node *node;
+ struct hlist_nulls_node *node;
struct udp_hslot *hslot = &state->udp_table->hash[state->bucket];
spin_lock_bh(&hslot->lock);
- sk_for_each(sk, node, &hslot->head) {
+ sk_nulls_for_each(sk, node, &hslot->head) {
if (!net_eq(sock_net(sk), net))
continue;
if (sk->sk_family == state->family)
@@ -1582,7 +1579,7 @@ static struct sock *udp_get_next(struct seq_file *seq, struct sock *sk)
struct net *net = seq_file_net(seq);
do {
- sk = sk_next(sk);
+ sk = sk_nulls_next(sk);
} while (sk && (!net_eq(sock_net(sk), net) || sk->sk_family != state->family));
if (!sk) {
@@ -1753,7 +1750,7 @@ void __init udp_table_init(struct udp_table *table)
int i;
for (i = 0; i < UDP_HTABLE_SIZE; i++) {
- INIT_HLIST_HEAD(&table->hash[i].head);
+ INIT_HLIST_NULLS_HEAD(&table->hash[i].head, i);
spin_lock_init(&table->hash[i].lock);
}
}