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net: listening_hash get a spinlock per bucket

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This patch prepares RCU migration of listening_hash table for
TCP/DCCP protocols.

listening_hash table being small (32 slots per protocol), we add
a spinlock for each slot, instead of a single rwlock for whole table.

This should reduce hold time of readers, and writers concurrency.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2008-11-20 00:40:07 -08:00
committed by David S. Miller
parent d8b83c57a7
commit 5caea4ea70
6 changed files with 79 additions and 119 deletions
Download Patch File Download Diff File Expand all files Collapse all files

86
net/ipv4/inet_hashtables.c
View File

@@ -110,35 +110,6 @@ void __inet_inherit_port(struct sock *sk, struct sock *child)
EXPORT_SYMBOL_GPL(__inet_inherit_port);
/*
* This lock without WQ_FLAG_EXCLUSIVE is good on UP and it can be very bad on SMP.
* Look, when several writers sleep and reader wakes them up, all but one
* immediately hit write lock and grab all the cpus. Exclusive sleep solves
* this, _but_ remember, it adds useless work on UP machines (wake up each
* exclusive lock release). It should be ifdefed really.
*/
void inet_listen_wlock(struct inet_hashinfo *hashinfo)
__acquires(hashinfo->lhash_lock)
{
write_lock(&hashinfo->lhash_lock);
if (atomic_read(&hashinfo->lhash_users)) {
DEFINE_WAIT(wait);
for (;;) {
prepare_to_wait_exclusive(&hashinfo->lhash_wait,
&wait, TASK_UNINTERRUPTIBLE);
if (!atomic_read(&hashinfo->lhash_users))
break;
write_unlock_bh(&hashinfo->lhash_lock);
schedule();
write_lock_bh(&hashinfo->lhash_lock);
}
finish_wait(&hashinfo->lhash_wait, &wait);
}
}
/*
* Don't inline this cruft. Here are some nice properties to exploit here. The
* BSD API does not allow a listening sock to specify the remote port nor the
@@ -191,25 +162,25 @@ struct sock *__inet_lookup_listener(struct net *net,
const int dif)
{
struct sock *sk = NULL;
const struct hlist_head *head;
struct inet_listen_hashbucket *ilb;
read_lock(&hashinfo->lhash_lock);
head = &hashinfo->listening_hash[inet_lhashfn(net, hnum)];
if (!hlist_empty(head)) {
const struct inet_sock *inet = inet_sk((sk = __sk_head(head)));
ilb = &hashinfo->listening_hash[inet_lhashfn(net, hnum)];
spin_lock(&ilb->lock);
if (!hlist_empty(&ilb->head)) {
const struct inet_sock *inet = inet_sk((sk = __sk_head(&ilb->head)));
if (inet->num == hnum && !sk->sk_node.next &&
(!inet->rcv_saddr || inet->rcv_saddr == daddr) &&
(sk->sk_family == PF_INET || !ipv6_only_sock(sk)) &&
!sk->sk_bound_dev_if && net_eq(sock_net(sk), net))
goto sherry_cache;
sk = inet_lookup_listener_slow(net, head, daddr, hnum, dif);
sk = inet_lookup_listener_slow(net, &ilb->head, daddr, hnum, dif);
}
if (sk) {
sherry_cache:
sock_hold(sk);
}
read_unlock(&hashinfo->lhash_lock);
spin_unlock(&ilb->lock);
return sk;
}
EXPORT_SYMBOL_GPL(__inet_lookup_listener);
@@ -389,8 +360,7 @@ EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
static void __inet_hash(struct sock *sk)
{
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
struct hlist_head *list;
rwlock_t *lock;
struct inet_listen_hashbucket *ilb;
if (sk->sk_state != TCP_LISTEN) {
__inet_hash_nolisten(sk);
@@ -398,14 +368,12 @@ static void __inet_hash(struct sock *sk)
}
WARN_ON(!sk_unhashed(sk));
list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
lock = &hashinfo->lhash_lock;
ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
inet_listen_wlock(hashinfo);
__sk_add_node(sk, list);
spin_lock(&ilb->lock);
__sk_add_node(sk, &ilb->head);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
write_unlock(lock);
wake_up(&hashinfo->lhash_wait);
spin_unlock(&ilb->lock);
}
void inet_hash(struct sock *sk)
@@ -420,29 +388,27 @@ EXPORT_SYMBOL_GPL(inet_hash);
void inet_unhash(struct sock *sk)
{
rwlock_t *lock;
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
if (sk_unhashed(sk))
goto out;
return;
if (sk->sk_state == TCP_LISTEN) {
local_bh_disable();
inet_listen_wlock(hashinfo);
lock = &hashinfo->lhash_lock;
struct inet_listen_hashbucket *ilb;
ilb = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
spin_lock_bh(&ilb->lock);
if (__sk_del_node_init(sk))
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
spin_unlock_bh(&ilb->lock);
} else {
lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
rwlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
write_lock_bh(lock);
if (__sk_nulls_del_node_init_rcu(sk))
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
write_unlock_bh(lock);
}
write_unlock_bh(lock);
out:
if (sk->sk_state == TCP_LISTEN)
wake_up(&hashinfo->lhash_wait);
}
EXPORT_SYMBOL_GPL(inet_unhash);
@@ -556,3 +522,13 @@ int inet_hash_connect(struct inet_timewait_death_row *death_row,
}
EXPORT_SYMBOL_GPL(inet_hash_connect);
void inet_hashinfo_init(struct inet_hashinfo *h)
{
int i;
for (i = 0; i < INET_LHTABLE_SIZE; i++)
spin_lock_init(&h->listening_hash[i].lock);
}
EXPORT_SYMBOL_GPL(inet_hashinfo_init);