[INET]: Remove struct dst_entry *dst from request_sock_ops.rtx_syn_ack.

It looks like dst parameter is used in this API due to historical
reasons.  Actually, it is really used in the direct call to
tcp_v4_send_synack only.  So, create a wrapper for tcp_v4_send_synack
and remove dst from rtx_syn_ack.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/ipv4.c b/net/dccp/ipv4.c
index 474075a..514a40b 100644
--- a/net/dccp/ipv4.c
+++ b/net/dccp/ipv4.c
@@ -471,15 +471,14 @@
 	return &rt->u.dst;
 }
 
-static int dccp_v4_send_response(struct sock *sk, struct request_sock *req,
-				 struct dst_entry *dst)
+static int dccp_v4_send_response(struct sock *sk, struct request_sock *req)
 {
 	int err = -1;
 	struct sk_buff *skb;
+	struct dst_entry *dst;
 
-	/* First, grab a route. */
-
-	if (dst == NULL && (dst = inet_csk_route_req(sk, req)) == NULL)
+	dst = inet_csk_route_req(sk, req);
+	if (dst == NULL)
 		goto out;
 
 	skb = dccp_make_response(sk, dst, req);
@@ -620,7 +619,7 @@
 	dreq->dreq_iss	   = dccp_v4_init_sequence(skb);
 	dreq->dreq_service = service;
 
-	if (dccp_v4_send_response(sk, req, NULL))
+	if (dccp_v4_send_response(sk, req))
 		goto drop_and_free;
 
 	inet_csk_reqsk_queue_hash_add(sk, req, DCCP_TIMEOUT_INIT);