tcp: avoid two atomic ops for syncookies

inet_reqsk_alloc() is used to allocate a temporary request
in order to generate a SYNACK with a cookie. Then later,
syncookie validation also uses a temporary request.

These paths already took a reference on listener refcount,
we can avoid a couple of atomic operations.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 8 insertions, 3 deletions

diff --git a/include/net/request_sock.h b/include/net/request_sock.h
index f83669460d82..95ab5d7aab96 100644
--- a/include/net/request_sock.h
+++ b/include/net/request_sock.h
@@ -80,7 +80,8 @@ static inline struct sock *req_to_sk(struct request_sock *req)
 }
 
 static inline struct request_sock *
-reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener)
+reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener,
+	    bool attach_listener)
 {
 	struct request_sock *req;
 
@@ -88,8 +89,12 @@ reqsk_alloc(const struct request_sock_ops *ops, struct sock *sk_listener)
 
 	if (req) {
 		req->rsk_ops = ops;
-		sock_hold(sk_listener);
-		req->rsk_listener = sk_listener;
+		if (attach_listener) {
+			sock_hold(sk_listener);
+			req->rsk_listener = sk_listener;
+		} else {
+			req->rsk_listener = NULL;
+		}
 		req_to_sk(req)->sk_prot = sk_listener->sk_prot;
 		sk_node_init(&req_to_sk(req)->sk_node);
 		sk_tx_queue_clear(req_to_sk(req));