tcp/dccp: add inet_csk_reqsk_queue_drop_and_put() helper

Let's reduce the confusion about inet_csk_reqsk_queue_drop() :
In many cases we also need to release reference on request socket,
so add a helper to do this, reducing code size and complexity.

Fixes: 4bdc3d66147b ("tcp/dccp: fix behavior of stale SYN_RECV request sockets")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/inet_connection_sock.h

@@ -299,6 +299,7 @@ static inline int inet_csk_reqsk_queue_is_full(const struct sock *sk)
 }
 
 void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req);
+void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req);
 
 void inet_csk_destroy_sock(struct sock *sk);
 void inet_csk_prepare_forced_close(struct sock *sk);

net/dccp/ipv4.c

@@ -828,7 +828,7 @@ lookup:
 		if (likely(sk->sk_state == DCCP_LISTEN)) {
 			nsk = dccp_check_req(sk, skb, req);
 		} else {
-			inet_csk_reqsk_queue_drop(sk, req);
+			inet_csk_reqsk_queue_drop_and_put(sk, req);
 			goto lookup;
 		}
 		if (!nsk) {

net/dccp/ipv6.c

@@ -686,7 +686,7 @@ lookup:
 		if (likely(sk->sk_state == DCCP_LISTEN)) {
 			nsk = dccp_check_req(sk, skb, req);
 		} else {
-			inet_csk_reqsk_queue_drop(sk, req);
+			inet_csk_reqsk_queue_drop_and_put(sk, req);
 			goto lookup;
 		}
 		if (!nsk) {

net/ipv4/inet_connection_sock.c

@@ -546,6 +546,13 @@ void inet_csk_reqsk_queue_drop(struct sock *sk, struct request_sock *req)
 }
 EXPORT_SYMBOL(inet_csk_reqsk_queue_drop);
 
+void inet_csk_reqsk_queue_drop_and_put(struct sock *sk, struct request_sock *req)
+{
+	inet_csk_reqsk_queue_drop(sk, req);
+	reqsk_put(req);
+}
+EXPORT_SYMBOL(inet_csk_reqsk_queue_drop_and_put);
+
 static void reqsk_timer_handler(unsigned long data)
 {
 	struct request_sock *req = (struct request_sock *)data;
@@ -608,8 +615,7 @@ static void reqsk_timer_handler(unsigned long data)
 		return;
 	}
 drop:
-	inet_csk_reqsk_queue_drop(sk_listener, req);
-	reqsk_put(req);
+	inet_csk_reqsk_queue_drop_and_put(sk_listener, req);
 }
 
 static void reqsk_queue_hash_req(struct request_sock *req,

net/ipv4/tcp_ipv4.c

@@ -1591,7 +1591,7 @@ process:
 		if (likely(sk->sk_state == TCP_LISTEN)) {
 			nsk = tcp_check_req(sk, skb, req, false);
 		} else {
-			inet_csk_reqsk_queue_drop(sk, req);
+			inet_csk_reqsk_queue_drop_and_put(sk, req);
 			goto lookup;
 		}
 		if (!nsk) {

net/ipv6/tcp_ipv6.c

@@ -1386,7 +1386,7 @@ process:
 		if (likely(sk->sk_state == TCP_LISTEN)) {
 			nsk = tcp_check_req(sk, skb, req, false);
 		} else {
-			inet_csk_reqsk_queue_drop(sk, req);
+			inet_csk_reqsk_queue_drop_and_put(sk, req);
 			goto lookup;
 		}
 		if (!nsk) {