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/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 330b08a..a81caa1 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1970,13 +1970,13 @@
struct sock *sk;
struct hlist_nulls_node *node;
struct inet_timewait_sock *tw;
- rwlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
+ spinlock_t *lock = inet_ehash_lockp(&tcp_hashinfo, st->bucket);
/* Lockless fast path for the common case of empty buckets */
if (empty_bucket(st))
continue;
- read_lock_bh(lock);
+ spin_lock_bh(lock);
sk_nulls_for_each(sk, node, &tcp_hashinfo.ehash[st->bucket].chain) {
if (sk->sk_family != st->family ||
!net_eq(sock_net(sk), net)) {
@@ -1995,7 +1995,7 @@
rc = tw;
goto out;
}
- read_unlock_bh(lock);
+ spin_unlock_bh(lock);
st->state = TCP_SEQ_STATE_ESTABLISHED;
}
out:
@@ -2023,7 +2023,7 @@
cur = tw;
goto out;
}
- read_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
+ spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
st->state = TCP_SEQ_STATE_ESTABLISHED;
/* Look for next non empty bucket */
@@ -2033,7 +2033,7 @@
if (st->bucket >= tcp_hashinfo.ehash_size)
return NULL;
- read_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
+ spin_lock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
sk = sk_nulls_head(&tcp_hashinfo.ehash[st->bucket].chain);
} else
sk = sk_nulls_next(sk);
@@ -2134,7 +2134,7 @@
case TCP_SEQ_STATE_TIME_WAIT:
case TCP_SEQ_STATE_ESTABLISHED:
if (v)
- read_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
+ spin_unlock_bh(inet_ehash_lockp(&tcp_hashinfo, st->bucket));
break;
}
}