inet: avoid fastopen lock for regular accept()

It is not because a TCP listener is FastOpen ready that
all incoming sockets actually used FastOpen.

Avoid taking queue->fastopenq->lock if not needed.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/inet_connection_sock.c

@@ -293,8 +293,8 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
 {
 	struct inet_connection_sock *icsk = inet_csk(sk);
 	struct request_sock_queue *queue = &icsk->icsk_accept_queue;
-	struct sock *newsk;
 	struct request_sock *req;
+	struct sock *newsk;
 	int error;
 
 	lock_sock(sk);
@@ -323,7 +323,9 @@ struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
 	newsk = req->sk;
 
 	sk_acceptq_removed(sk);
-	if (sk->sk_protocol == IPPROTO_TCP && queue->fastopenq != NULL) {
+	if (sk->sk_protocol == IPPROTO_TCP &&
+	    tcp_rsk(req)->tfo_listener &&
+	    queue->fastopenq) {
 		spin_lock_bh(&queue->fastopenq->lock);
 		if (tcp_rsk(req)->tfo_listener) {
 			/* We are still waiting for the final ACK from 3WHS