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/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 21544b9..e0fd681 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -38,14 +38,14 @@
} else {
unsigned int hash;
struct hlist_nulls_head *list;
- rwlock_t *lock;
+ spinlock_t *lock;
sk->sk_hash = hash = inet6_sk_ehashfn(sk);
list = &inet_ehash_bucket(hashinfo, hash)->chain;
lock = inet_ehash_lockp(hashinfo, hash);
- write_lock(lock);
+ spin_lock(lock);
__sk_nulls_add_node_rcu(sk, list);
- write_unlock(lock);
+ spin_unlock(lock);
}
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
@@ -195,13 +195,12 @@
const unsigned int hash = inet6_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) {
@@ -230,8 +229,8 @@
WARN_ON(!sk_unhashed(sk));
__sk_nulls_add_node_rcu(sk, &head->chain);
sk->sk_hash = hash;
+ spin_unlock(lock);
sock_prot_inuse_add(sock_net(sk), sk->sk_prot, 1);
- write_unlock(lock);
if (twp != NULL) {
*twp = tw;
@@ -246,7 +245,7 @@
return 0;
not_unique:
- write_unlock(lock);
+ spin_unlock(lock);
return -EADDRNOTAVAIL;
}