[NET] Generalise tcp_listen_opt

This chunks out the accept_queue and tcp_listen_opt code and moves
them to net/core/request_sock.c and include/net/request_sock.h, to
make it useful for other transport protocols, DCCP being the first one
to use it.

Next patches will rename tcp_listen_opt to accept_sock and remove the
inline tcp functions that just call a reqsk_queue_ function.

Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 068cd4a..84091da 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -401,7 +401,7 @@
 					      struct in6_addr *laddr,
 					      int iif)
 {
-	struct tcp_listen_opt *lopt = tp->listen_opt;
+	struct tcp_listen_opt *lopt = tp->accept_queue.listen_opt;
 	struct request_sock *req, **prev;  
 
 	for (prev = &lopt->syn_table[tcp_v6_synq_hash(raddr, rport, lopt->hash_rnd)];
@@ -1267,18 +1267,10 @@
 static void tcp_v6_synq_add(struct sock *sk, struct request_sock *req)
 {
 	struct tcp_sock *tp = tcp_sk(sk);
-	struct tcp_listen_opt *lopt = tp->listen_opt;
+	struct tcp_listen_opt *lopt = tp->accept_queue.listen_opt;
 	u32 h = tcp_v6_synq_hash(&tcp6_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port, lopt->hash_rnd);
 
-	req->sk = NULL;
-	req->expires = jiffies + TCP_TIMEOUT_INIT;
-	req->retrans = 0;
-	req->dl_next = lopt->syn_table[h];
-
-	write_lock(&tp->syn_wait_lock);
-	lopt->syn_table[h] = req;
-	write_unlock(&tp->syn_wait_lock);
-
+	reqsk_queue_hash_req(&tp->accept_queue, h, req, TCP_TIMEOUT_INIT);
 	tcp_synq_added(sk);
 }