net: convert TCP/DCCP ehash rwlocks to spinlocks
Now TCP & DCCP use RCU lookups, we can convert ehash rwlocks to spinlocks.
/proc/net/tcp and other seq_file 'readers' can safely be converted to 'writers'.
This should speedup writers, since spin_lock()/spin_unlock()
only use one atomic operation instead of two for write_lock()/write_unlock()
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 377d004..4c273a9 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -271,13 +271,12 @@
struct net *net = sock_net(sk);
unsigned int hash = inet_ehashfn(net, daddr, lport, saddr, inet->dport);
struct inet_ehash_bucket *head = inet_ehash_bucket(hinfo, hash);
- rwlock_t *lock = inet_ehash_lockp(hinfo, hash);
+ spinlock_t *lock = inet_ehash_lockp(hinfo, hash);
struct sock *sk2;
const struct hlist_nulls_node *node;
struct inet_timewait_sock *tw;
- prefetch(head->chain.first);
- write_lock(lock);
+ spin_lock(lock);
/* Check TIME-WAIT sockets first. */
sk_nulls_for_each(sk2, node, &head->twchain) {
@@ -308,8 +307,8 @@
sk->sk_hash = hash;
WARN_ON(!sk_unhashed(sk));
__sk_nulls_add_node_rcu(sk, &head->chain);
+ spin_unlock(lock);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
- write_unlock(lock);
if (twp) {
*twp = tw;
@@ -325,7 +324,7 @@
return 0;
not_unique:
- write_unlock(lock);
+ spin_unlock(lock);
return -EADDRNOTAVAIL;
}
@@ -340,7 +339,7 @@
{
struct inet_hashinfo *hashinfo = sk->sk_prot->h.hashinfo;
struct hlist_nulls_head *list;
- rwlock_t *lock;
+ spinlock_t *lock;
struct inet_ehash_bucket *head;
WARN_ON(!sk_unhashed(sk));
@@ -350,10 +349,10 @@
list = &head->chain;
lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
- write_lock(lock);
+ spin_lock(lock);
__sk_nulls_add_node_rcu(sk, list);
+ spin_unlock(lock);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
- write_unlock(lock);
}
EXPORT_SYMBOL_GPL(__inet_hash_nolisten);
@@ -402,12 +401,12 @@
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1);
spin_unlock_bh(&ilb->lock);
} else {
- rwlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
+ spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash);
- write_lock_bh(lock);
+ spin_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);
+ spin_unlock_bh(lock);
}
}
EXPORT_SYMBOL_GPL(inet_unhash);