inet: drop prev pointer handling in request sock

When request sock are put in ehash table, the whole notion
of having a previous request to update dl_next is pointless.

Also, following patch will get rid of big purge timer,
so we want to delete a request sock without holding listener lock.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/dccp/minisocks.c b/net/dccp/minisocks.c
index b50dc43..332f7d6 100644
--- a/net/dccp/minisocks.c
+++ b/net/dccp/minisocks.c
@@ -152,8 +152,7 @@
  * as an request_sock.
  */
 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
-			    struct request_sock *req,
-			    struct request_sock **prev)
+			    struct request_sock *req)
 {
 	struct sock *child = NULL;
 	struct dccp_request_sock *dreq = dccp_rsk(req);
@@ -200,7 +199,7 @@
 	if (child == NULL)
 		goto listen_overflow;
 
-	inet_csk_reqsk_queue_unlink(sk, req, prev);
+	inet_csk_reqsk_queue_unlink(sk, req);
 	inet_csk_reqsk_queue_removed(sk, req);
 	inet_csk_reqsk_queue_add(sk, req, child);
 out:
@@ -212,7 +211,7 @@
 	if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 		req->rsk_ops->send_reset(sk, skb);
 
-	inet_csk_reqsk_queue_drop(sk, req, prev);
+	inet_csk_reqsk_queue_drop(sk, req);
 	goto out;
 }