o sock: remove sk_prev

Move it to the protocols that we're using this pointers for other
purposes than a list pointer as the name implies, namely tcp and
sctp, where they are used as a pointer to the bind_hash. Shrink,
struct sock, shrink! :-)

include/linux/tcp.h

@@ -219,7 +219,7 @@ struct tcp_opt {
  	__u32	snd_sml;	/* Last byte of the most recently transmitted small packet */
 	__u32	rcv_tstamp;	/* timestamp of last received ACK (for keepalives) */
 	__u32	lsndtime;	/* timestamp of last sent data packet (for restart window) */
-
+	struct tcp_bind_bucket *bind_hash;
 	/* Delayed ACK control data */
 	struct {
 		__u8	pending;	/* ACK is pending */

include/net/sctp/structs.h

@@ -313,6 +313,7 @@ struct sctp_opt {
 	/* What is our base endpointer? */
 	struct sctp_endpoint *ep;
 
+	struct sctp_bind_bucket *bind_hash;
 	/* Various Socket Options.  */
 	__u16 default_stream;
 	__u32 default_ppid;

include/net/sock.h

@@ -133,7 +133,6 @@ struct sock_common {
   *	@sk_forward_alloc - space allocated forward
   *	@sk_allocation - allocation mode
   *	@sk_sndbuf - size of send buffer in bytes
-  *	@sk_prev - pointer to previous sock in the list this sock is in
   *	@sk_flags - %SO_LINGER (l_onoff), %SO_BROADCAST, %SO_KEEPALIVE, %SO_OOBINLINE settings
   *	@sk_no_check - %SO_NO_CHECK setting, wether or not checkup packets
   *	@sk_debug - %SO_DEBUG setting
@@ -206,7 +205,6 @@ struct sock {
 	int			sk_forward_alloc;
 	unsigned int		sk_allocation;
 	int			sk_sndbuf;
-	struct sock		*sk_prev;
 	unsigned long 		sk_flags;
 	char		 	sk_no_check;
 	unsigned char		sk_debug;

include/net/tcp.h

@@ -1475,7 +1475,8 @@ static __inline__ void tcp_set_state(struct sock *sk, int state)
 			TCP_INC_STATS(TcpEstabResets);
 
 		sk->sk_prot->unhash(sk);
-		if (sk->sk_prev && !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
+		if (tcp_sk(sk)->bind_hash &&
+		    !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
 			tcp_put_port(sk);
 		/* fall through */
 	default:

net/ipv4/tcp.c

@@ -1909,7 +1909,7 @@ void tcp_destroy_sock(struct sock *sk)
 	BUG_TRAP(sk_unhashed(sk));
 
 	/* If it has not 0 inet_sk(sk)->num, it must be bound */
-	BUG_TRAP(!inet_sk(sk)->num || sk->sk_prev);
+	BUG_TRAP(!inet_sk(sk)->num || tcp_sk(sk)->bind_hash);
 
 #ifdef TCP_DEBUG
 	if (sk->sk_zapped) {
@@ -2164,7 +2164,7 @@ int tcp_disconnect(struct sock *sk, int flags)
 	tcp_sack_reset(tp);
 	__sk_dst_reset(sk);
 
-	BUG_TRAP(!inet->num || sk->sk_prev);
+	BUG_TRAP(!inet->num || tp->bind_hash);
 
 	sk->sk_error_report(sk);
 	return err;

net/ipv4/tcp_ipv4.c

@@ -156,9 +156,9 @@ static __inline__ void __tcp_inherit_port(struct sock *sk, struct sock *child)
 	struct tcp_bind_bucket *tb;
 
 	spin_lock(&head->lock);
-	tb = (struct tcp_bind_bucket *)sk->sk_prev;
+	tb = tcp_sk(sk)->bind_hash;
 	sk_add_bind_node(child, &tb->owners);
-	child->sk_prev	  = (struct sock *)tb;
+	tcp_sk(child)->bind_hash = tb;
 	spin_unlock(&head->lock);
 }
 
@@ -174,7 +174,7 @@ void tcp_bind_hash(struct sock *sk, struct tcp_bind_bucket *tb,
 {
 	inet_sk(sk)->num = snum;
 	sk_add_bind_node(sk, &tb->owners);
-	sk->sk_prev       = (struct sock *)tb;
+	tcp_sk(sk)->bind_hash = tb;
 }
 
 static inline int tcp_bind_conflict(struct sock *sk, struct tcp_bind_bucket *tb)
@@ -279,9 +279,9 @@ static int tcp_v4_get_port(struct sock *sk, unsigned short snum)
 		   (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
 		tb->fastreuse = 0;
 success:
-	if (!sk->sk_prev)
+	if (!tcp_sk(sk)->bind_hash)
 		tcp_bind_hash(sk, tb, snum);
-	BUG_TRAP(sk->sk_prev == (struct sock *)tb);
+	BUG_TRAP(tcp_sk(sk)->bind_hash == tb);
  	ret = 0;
 
 fail_unlock:
@@ -301,9 +301,9 @@ static void __tcp_put_port(struct sock *sk)
 	struct tcp_bind_bucket *tb;
 
 	spin_lock(&head->lock);
-	tb = (struct tcp_bind_bucket *)sk->sk_prev;
+	tb = tcp_sk(sk)->bind_hash;
 	__hlist_del(&sk->sk_bind_node);
-	sk->sk_prev = NULL;
+	tcp_sk(sk)->bind_hash = NULL;
 	inet->num = 0;
 	tcp_bucket_destroy(tb);
 	spin_unlock(&head->lock);
@@ -730,7 +730,7 @@ static int tcp_v4_hash_connect(struct sock *sk)
  	}
 
  	head  = &tcp_bhash[tcp_bhashfn(snum)];
- 	tb  = (struct tcp_bind_bucket *)sk->sk_prev;
+ 	tb  = tcp_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);
@@ -2101,7 +2101,7 @@ static int tcp_v4_destroy_sock(struct sock *sk)
 	__skb_queue_purge(&tp->ucopy.prequeue);
 
 	/* Clean up a referenced TCP bind bucket. */
-	if (sk->sk_prev)
+	if (tp->bind_hash)
 		tcp_put_port(sk);
 
 	/* If sendmsg cached page exists, toss it. */

net/ipv4/tcp_minisocks.c

@@ -301,8 +301,8 @@ static void __tcp_tw_hashdance(struct sock *sk, struct tcp_tw_bucket *tw)
 	 */
 	bhead = &tcp_bhash[tcp_bhashfn(inet_sk(sk)->num)];
 	spin_lock(&bhead->lock);
-	tw->tw_tb = (struct tcp_bind_bucket *)sk->sk_prev;
-	BUG_TRAP(sk->sk_prev);
+	tw->tw_tb = tcp_sk(sk)->bind_hash;
+	BUG_TRAP(tcp_sk(sk)->bind_hash);
 	tw_add_bind_node(tw, &tw->tw_tb->owners);
 	spin_unlock(&bhead->lock);
 
@@ -620,7 +620,7 @@ struct sock *tcp_create_openreq_child(struct sock *sk, struct open_request *req,
 
 		/* SANITY */
 		sk_node_init(&newsk->sk_node);
-		newsk->sk_prev = NULL;
+		tcp_sk(newsk)->bind_hash = NULL;
 
 		/* Clone the TCP header template */
 		inet_sk(newsk)->dport = req->rmt_port;

net/ipv6/tcp_ipv6.c

@@ -225,9 +225,9 @@ static int tcp_v6_get_port(struct sock *sk, unsigned short snum)
 		tb->fastreuse = 0;
 
 success:
-	if (!sk->sk_prev)
+	if (!tcp_sk(sk)->bind_hash)
 		tcp_bind_hash(sk, tb, snum);
-	BUG_TRAP(sk->sk_prev == (struct sock *)tb);
+	BUG_TRAP(tcp_sk(sk)->bind_hash == tb);
 	ret = 0;
 
 fail_unlock:
@@ -1947,7 +1947,7 @@ static int tcp_v6_destroy_sock(struct sock *sk)
 	__skb_queue_purge(&tp->ucopy.prequeue);
 
 	/* Clean up a referenced TCP bind bucket. */
-	if (sk->sk_prev)
+	if (tcp_sk(sk)->bind_hash)
 		tcp_put_port(sk);
 
 	/* If sendmsg cached page exists, toss it. */

net/sctp/endpointola.c

@@ -209,7 +209,7 @@ void sctp_endpoint_destroy(struct sctp_endpoint *ep)
 	sctp_bind_addr_free(&ep->base.bind_addr);
 
 	/* Remove and free the port */
-	if (ep->base.sk->sk_prev)
+	if (sctp_sk(ep->base.sk)->bind_hash)
 		sctp_put_port(ep->base.sk);
 
 	/* Give up our hold on the sock. */

net/sctp/socket.c

@@ -3078,9 +3078,9 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
 	 */
 success:
 	inet_sk(sk)->num = snum;
-	if (!sk->sk_prev) {
+	if (!sctp_sk(sk)->bind_hash) {
 		sk_add_bind_node(sk, &pp->sk_list);
-		sk->sk_prev = (struct sock *) pp;
+		sctp_sk(sk)->bind_hash = pp;
 	}
 	ret = 0;
 
@@ -3345,9 +3345,9 @@ static __inline__ void __sctp_put_port(struct sock *sk)
 	struct sctp_bind_bucket *pp;
 
 	sctp_spin_lock(&head->lock);
-	pp = (struct sctp_bind_bucket *)sk->sk_prev;
+	pp = sctp_sk(sk)->bind_hash;
 	hlist_del(&sk->sk_bind_node);
-	sk->sk_prev = NULL;
+	sctp_sk(sk)->bind_hash = NULL;
 	inet_sk(sk)->num = 0;
 	sctp_bucket_destroy(pp);
 	sctp_spin_unlock(&head->lock);