inet: minor optimization for backlog setting in listen(2)

Set the backlog earlier in inet_dccp_listen() and inet_listen(),
then we can avoid the redundant setting.
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/dccp/proto.c

@@ -948,6 +948,7 @@ int inet_dccp_listen(struct socket *sock, int backlog)
 	if (!((1 << old_state) & (DCCPF_CLOSED | DCCPF_LISTEN)))
 		goto out;
 
+	sk->sk_max_ack_backlog = backlog;
 	/* Really, if the socket is already in listen state
 	 * we can only allow the backlog to be adjusted.
 	 */
@@ -960,7 +961,6 @@ int inet_dccp_listen(struct socket *sock, int backlog)
 		if (err)
 			goto out;
 	}
-	sk->sk_max_ack_backlog = backlog;
 	err = 0;
 
 out:

net/ipv4/af_inet.c

@@ -208,6 +208,7 @@ int inet_listen(struct socket *sock, int backlog)
 	if (!((1 << old_state) & (TCPF_CLOSE | TCPF_LISTEN)))
 		goto out;
 
+	sk->sk_max_ack_backlog = backlog;
 	/* Really, if the socket is already in listen state
 	 * we can only allow the backlog to be adjusted.
 	 */
@@ -231,7 +232,6 @@ int inet_listen(struct socket *sock, int backlog)
 			goto out;
 		tcp_call_bpf(sk, BPF_SOCK_OPS_TCP_LISTEN_CB, 0, NULL);
 	}
-	sk->sk_max_ack_backlog = backlog;
 	err = 0;
 
 out:

net/ipv4/inet_connection_sock.c

@@ -881,7 +881,6 @@ int inet_csk_listen_start(struct sock *sk, int backlog)
 
 	reqsk_queue_alloc(&icsk->icsk_accept_queue);
 
-	sk->sk_max_ack_backlog = backlog;
 	sk->sk_ack_backlog = 0;
 	inet_csk_delack_init(sk);