net: listening_hash get a spinlock per bucket
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>
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index fd269cf..377d004 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -111,35 +111,6 @@
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
* remote address for the connection. So always assume those are both
@@ -191,25 +162,25 @@
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 @@
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 @@
}
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 @@
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 @@
}
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);
