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/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 5559fea..330b08a 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -97,11 +97,7 @@
}
#endif
-struct inet_hashinfo __cacheline_aligned tcp_hashinfo = {
- .lhash_lock = __RW_LOCK_UNLOCKED(tcp_hashinfo.lhash_lock),
- .lhash_users = ATOMIC_INIT(0),
- .lhash_wait = __WAIT_QUEUE_HEAD_INITIALIZER(tcp_hashinfo.lhash_wait),
-};
+struct inet_hashinfo tcp_hashinfo;
static inline __u32 tcp_v4_init_sequence(struct sk_buff *skb)
{
@@ -1874,15 +1870,18 @@
struct inet_connection_sock *icsk;
struct hlist_node *node;
struct sock *sk = cur;
+ struct inet_listen_hashbucket *ilb;
struct tcp_iter_state *st = seq->private;
struct net *net = seq_file_net(seq);
if (!sk) {
st->bucket = 0;
- sk = sk_head(&tcp_hashinfo.listening_hash[0]);
+ ilb = &tcp_hashinfo.listening_hash[0];
+ spin_lock_bh(&ilb->lock);
+ sk = sk_head(&ilb->head);
goto get_sk;
}
-
+ ilb = &tcp_hashinfo.listening_hash[st->bucket];
++st->num;
if (st->state == TCP_SEQ_STATE_OPENREQ) {
@@ -1932,8 +1931,11 @@
}
read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
}
+ spin_unlock_bh(&ilb->lock);
if (++st->bucket < INET_LHTABLE_SIZE) {
- sk = sk_head(&tcp_hashinfo.listening_hash[st->bucket]);
+ ilb = &tcp_hashinfo.listening_hash[st->bucket];
+ spin_lock_bh(&ilb->lock);
+ sk = sk_head(&ilb->head);
goto get_sk;
}
cur = NULL;
@@ -2066,12 +2068,10 @@
void *rc;
struct tcp_iter_state *st = seq->private;
- inet_listen_lock(&tcp_hashinfo);
st->state = TCP_SEQ_STATE_LISTENING;
rc = listening_get_idx(seq, &pos);
if (!rc) {
- inet_listen_unlock(&tcp_hashinfo);
st->state = TCP_SEQ_STATE_ESTABLISHED;
rc = established_get_idx(seq, pos);
}
@@ -2103,7 +2103,6 @@
case TCP_SEQ_STATE_LISTENING:
rc = listening_get_next(seq, v);
if (!rc) {
- inet_listen_unlock(&tcp_hashinfo);
st->state = TCP_SEQ_STATE_ESTABLISHED;
rc = established_get_first(seq);
}
@@ -2130,7 +2129,7 @@
}
case TCP_SEQ_STATE_LISTENING:
if (v != SEQ_START_TOKEN)
- inet_listen_unlock(&tcp_hashinfo);
+ spin_unlock_bh(&tcp_hashinfo.listening_hash[st->bucket].lock);
break;
case TCP_SEQ_STATE_TIME_WAIT:
case TCP_SEQ_STATE_ESTABLISHED:
@@ -2405,6 +2404,7 @@
void __init tcp_v4_init(void)
{
+ inet_hashinfo_init(&tcp_hashinfo);
if (register_pernet_device(&tcp_sk_ops))
panic("Failed to create the TCP control socket.\n");
}