[INET]: Generalise the tcp_listen_ lock routines

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_hashtables.h

@@ -19,10 +19,14 @@
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
+#include <linux/tcp.h>		/* only for TCP_LISTEN, damn :-( */
 #include <linux/types.h>
+#include <linux/wait.h>
 
 #include <net/sock.h>
 
+#include <asm/atomic.h>
+
 /* This is for all connections with a full identity, no wildcards.
  * New scheme, half the table is for TIME_WAIT, the other half is
  * for the rest.  I'll experiment with dynamic table growth later.
@@ -192,4 +196,48 @@ static inline void inet_inherit_port(struct inet_hashinfo *table,
 
 extern void inet_put_port(struct inet_hashinfo *table, struct sock *sk);
 
+extern void inet_listen_wlock(struct inet_hashinfo *hashinfo);
+
+/*
+ * - We may sleep inside this lock.
+ * - If sleeping is not required (or called from BH),
+ *   use plain read_(un)lock(&inet_hashinfo.lhash_lock).
+ */
+static inline void inet_listen_lock(struct inet_hashinfo *hashinfo)
+{
+	/* read_lock synchronizes to candidates to writers */
+	read_lock(&hashinfo->lhash_lock);
+	atomic_inc(&hashinfo->lhash_users);
+	read_unlock(&hashinfo->lhash_lock);
+}
+
+static inline void inet_listen_unlock(struct inet_hashinfo *hashinfo)
+{
+	if (atomic_dec_and_test(&hashinfo->lhash_users))
+		wake_up(&hashinfo->lhash_wait);
+}
+
+static inline void __inet_hash(struct inet_hashinfo *hashinfo,
+			       struct sock *sk, const int listen_possible)
+{
+	struct hlist_head *list;
+	rwlock_t *lock;
+
+	BUG_TRAP(sk_unhashed(sk));
+	if (listen_possible && sk->sk_state == TCP_LISTEN) {
+		list = &hashinfo->listening_hash[inet_sk_listen_hashfn(sk)];
+		lock = &hashinfo->lhash_lock;
+		inet_listen_wlock(hashinfo);
+	} else {
+		sk->sk_hashent = inet_sk_ehashfn(sk, hashinfo->ehash_size);
+		list = &hashinfo->ehash[sk->sk_hashent].chain;
+		lock = &hashinfo->ehash[sk->sk_hashent].lock;
+		write_lock(lock);
+	}
+	__sk_add_node(sk, list);
+	sock_prot_inc_use(sk->sk_prot);
+	write_unlock(lock);
+	if (listen_possible && sk->sk_state == TCP_LISTEN)
+		wake_up(&hashinfo->lhash_wait);
+}
 #endif /* _INET_HASHTABLES_H */

include/net/tcp.h

@@ -1447,27 +1447,6 @@ static __inline__ void tcp_openreq_init(struct request_sock *req,
 
 extern void tcp_enter_memory_pressure(void);
 
-extern void tcp_listen_wlock(void);
-
-/* - We may sleep inside this lock.
- * - If sleeping is not required (or called from BH),
- *   use plain read_(un)lock(&inet_hashinfo.lhash_lock).
- */
-
-static inline void tcp_listen_lock(void)
-{
-	/* read_lock synchronizes to candidates to writers */
-	read_lock(&tcp_hashinfo.lhash_lock);
-	atomic_inc(&tcp_hashinfo.lhash_users);
-	read_unlock(&tcp_hashinfo.lhash_lock);
-}
-
-static inline void tcp_listen_unlock(void)
-{
-	if (atomic_dec_and_test(&tcp_hashinfo.lhash_users))
-		wake_up(&tcp_hashinfo.lhash_wait);
-}
-
 static inline int keepalive_intvl_when(const struct tcp_sock *tp)
 {
 	return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;

net/ipv4/inet_hashtables.c

@@ -15,7 +15,9 @@
 
 #include <linux/config.h>
 #include <linux/module.h>
+#include <linux/sched.h>
 #include <linux/slab.h>
+#include <linux/wait.h>
 
 #include <net/inet_hashtables.h>
 
@@ -89,3 +91,33 @@ void inet_put_port(struct inet_hashinfo *hashinfo, struct sock *sk)
 }
 
 EXPORT_SYMBOL(inet_put_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)
+{
+	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);
+	}
+}
+
+EXPORT_SYMBOL(inet_listen_wlock);

net/ipv4/tcp_diag.c

@@ -589,7 +589,7 @@ static int tcpdiag_dump(struct sk_buff *skb, struct netlink_callback *cb)
 	if (cb->args[0] == 0) {
 		if (!(r->tcpdiag_states&(TCPF_LISTEN|TCPF_SYN_RECV)))
 			goto skip_listen_ht;
-		tcp_listen_lock();
+		inet_listen_lock(&tcp_hashinfo);
 		for (i = s_i; i < INET_LHTABLE_SIZE; i++) {
 			struct sock *sk;
 			struct hlist_node *node;
@@ -613,7 +613,7 @@ static int tcpdiag_dump(struct sk_buff *skb, struct netlink_callback *cb)
 					goto syn_recv;
 
 				if (tcpdiag_dump_sock(skb, sk, cb) < 0) {
-					tcp_listen_unlock();
+					inet_listen_unlock(&tcp_hashinfo);
 					goto done;
 				}
 
@@ -622,7 +622,7 @@ static int tcpdiag_dump(struct sk_buff *skb, struct netlink_callback *cb)
 					goto next_listen;
 
 				if (tcpdiag_dump_reqs(skb, sk, cb) < 0) {
-					tcp_listen_unlock();
+					inet_listen_unlock(&tcp_hashinfo);
 					goto done;
 				}
 
@@ -636,7 +636,7 @@ static int tcpdiag_dump(struct sk_buff *skb, struct netlink_callback *cb)
 			cb->args[3] = 0;
 			cb->args[4] = 0;
 		}
-		tcp_listen_unlock();
+		inet_listen_unlock(&tcp_hashinfo);
 skip_listen_ht:
 		cb->args[0] = 1;
 		s_i = num = s_num = 0;

net/ipv4/tcp_ipv4.c

@@ -228,62 +228,11 @@ static int tcp_v4_get_port(struct sock *sk, unsigned short snum)
 	return ret;
 }
 
-/* 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 tcp_listen_wlock(void)
-{
-	write_lock(&tcp_hashinfo.lhash_lock);
-
-	if (atomic_read(&tcp_hashinfo.lhash_users)) {
-		DEFINE_WAIT(wait);
-
-		for (;;) {
-			prepare_to_wait_exclusive(&tcp_hashinfo.lhash_wait,
-						&wait, TASK_UNINTERRUPTIBLE);
-			if (!atomic_read(&tcp_hashinfo.lhash_users))
-				break;
-			write_unlock_bh(&tcp_hashinfo.lhash_lock);
-			schedule();
-			write_lock_bh(&tcp_hashinfo.lhash_lock);
-		}
-
-		finish_wait(&tcp_hashinfo.lhash_wait, &wait);
-	}
-}
-
-static __inline__ void __tcp_v4_hash(struct sock *sk, const int listen_possible)
-{
-	struct hlist_head *list;
-	rwlock_t *lock;
-
-	BUG_TRAP(sk_unhashed(sk));
-	if (listen_possible && sk->sk_state == TCP_LISTEN) {
-		list = &tcp_hashinfo.listening_hash[inet_sk_listen_hashfn(sk)];
-		lock = &tcp_hashinfo.lhash_lock;
-		tcp_listen_wlock();
-	} else {
-		sk->sk_hashent = inet_sk_ehashfn(sk, tcp_hashinfo.ehash_size);
-		list = &tcp_hashinfo.ehash[sk->sk_hashent].chain;
-		lock = &tcp_hashinfo.ehash[sk->sk_hashent].lock;
-		write_lock(lock);
-	}
-	__sk_add_node(sk, list);
-	sock_prot_inc_use(sk->sk_prot);
-	write_unlock(lock);
-	if (listen_possible && sk->sk_state == TCP_LISTEN)
-		wake_up(&tcp_hashinfo.lhash_wait);
-}
-
 static void tcp_v4_hash(struct sock *sk)
 {
 	if (sk->sk_state != TCP_CLOSE) {
 		local_bh_disable();
-		__tcp_v4_hash(sk, 1);
+		__inet_hash(&tcp_hashinfo, sk, 1);
 		local_bh_enable();
 	}
 }
@@ -297,7 +246,7 @@ void tcp_unhash(struct sock *sk)
 
 	if (sk->sk_state == TCP_LISTEN) {
 		local_bh_disable();
-		tcp_listen_wlock();
+		inet_listen_wlock(&tcp_hashinfo);
 		lock = &tcp_hashinfo.lhash_lock;
 	} else {
 		struct inet_ehash_bucket *head = &tcp_hashinfo.ehash[sk->sk_hashent];
@@ -624,7 +573,7 @@ static inline int tcp_v4_hash_connect(struct sock *sk)
  		inet_bind_hash(sk, tb, port);
 		if (sk_unhashed(sk)) {
  			inet_sk(sk)->sport = htons(port);
- 			__tcp_v4_hash(sk, 0);
+ 			__inet_hash(&tcp_hashinfo, sk, 0);
  		}
  		spin_unlock(&head->lock);
 
@@ -641,7 +590,7 @@ static inline int tcp_v4_hash_connect(struct sock *sk)
  	tb  = inet_sk(sk)->bind_hash;
 	spin_lock_bh(&head->lock);
 	if (sk_head(&tb->owners) == sk && !sk->sk_bind_node.next) {
-		__tcp_v4_hash(sk, 0);
+		__inet_hash(&tcp_hashinfo, sk, 0);
 		spin_unlock_bh(&head->lock);
 		return 0;
 	} else {
@@ -1479,7 +1428,7 @@ struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
 	newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
 	tcp_initialize_rcv_mss(newsk);
 
-	__tcp_v4_hash(newsk, 0);
+	__inet_hash(&tcp_hashinfo, newsk, 0);
 	__inet_inherit_port(&tcp_hashinfo, sk, newsk);
 
 	return newsk;
@@ -2102,12 +2051,12 @@ static void *tcp_get_idx(struct seq_file *seq, loff_t pos)
 	void *rc;
 	struct tcp_iter_state* st = seq->private;
 
-	tcp_listen_lock();
+	inet_listen_lock(&tcp_hashinfo);
 	st->state = TCP_SEQ_STATE_LISTENING;
 	rc	  = listening_get_idx(seq, &pos);
 
 	if (!rc) {
-		tcp_listen_unlock();
+		inet_listen_unlock(&tcp_hashinfo);
 		local_bh_disable();
 		st->state = TCP_SEQ_STATE_ESTABLISHED;
 		rc	  = established_get_idx(seq, pos);
@@ -2140,7 +2089,7 @@ static void *tcp_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 	case TCP_SEQ_STATE_LISTENING:
 		rc = listening_get_next(seq, v);
 		if (!rc) {
-			tcp_listen_unlock();
+			inet_listen_unlock(&tcp_hashinfo);
 			local_bh_disable();
 			st->state = TCP_SEQ_STATE_ESTABLISHED;
 			rc	  = established_get_first(seq);
@@ -2168,7 +2117,7 @@ static void tcp_seq_stop(struct seq_file *seq, void *v)
 		}
 	case TCP_SEQ_STATE_LISTENING:
 		if (v != SEQ_START_TOKEN)
-			tcp_listen_unlock();
+			inet_listen_unlock(&tcp_hashinfo);
 		break;
 	case TCP_SEQ_STATE_TIME_WAIT:
 	case TCP_SEQ_STATE_ESTABLISHED:
@@ -2431,7 +2380,6 @@ void __init tcp_v4_init(struct net_proto_family *ops)
 EXPORT_SYMBOL(ipv4_specific);
 EXPORT_SYMBOL(inet_bind_bucket_create);
 EXPORT_SYMBOL(tcp_hashinfo);
-EXPORT_SYMBOL(tcp_listen_wlock);
 EXPORT_SYMBOL(tcp_prot);
 EXPORT_SYMBOL(tcp_unhash);
 EXPORT_SYMBOL(tcp_v4_conn_request);

net/ipv6/tcp_ipv6.c

@@ -229,7 +229,7 @@ static __inline__ void __tcp_v6_hash(struct sock *sk)
 	if (sk->sk_state == TCP_LISTEN) {
 		list = &tcp_hashinfo.listening_hash[inet_sk_listen_hashfn(sk)];
 		lock = &tcp_hashinfo.lhash_lock;
-		tcp_listen_wlock();
+		inet_listen_wlock(&tcp_hashinfo);
 	} else {
 		sk->sk_hashent = tcp_v6_sk_hashfn(sk);
 		list = &tcp_hashinfo.ehash[sk->sk_hashent].chain;