tcp: Rearrange tests in inet_csk_bind_conflict().

The following patch adds code in the !inet_use_bhash2_on_bind(sk)
case in inet_csk_bind_conflict().

To avoid adding nest and make the change cleaner, this patch
rearranges tests in inet_csk_bind_conflict().

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

Author: q2ven

net/ipv4/inet_connection_sock.c

@@ -242,42 +242,40 @@ static int inet_csk_bind_conflict(const struct sock *sk,
 				  const struct inet_bind2_bucket *tb2, /* may be null */
 				  bool relax, bool reuseport_ok)
 {
-	bool reuseport_cb_ok;
-	struct sock_reuseport *reuseport_cb;
 	kuid_t uid = sock_i_uid((struct sock *)sk);
+	struct sock_reuseport *reuseport_cb;
+	bool reuseport_cb_ok;
+	struct sock *sk2;
 
 	rcu_read_lock();
 	reuseport_cb = rcu_dereference(sk->sk_reuseport_cb);
 	/* paired with WRITE_ONCE() in __reuseport_(add|detach)_closed_sock */
 	reuseport_cb_ok = !reuseport_cb || READ_ONCE(reuseport_cb->num_closed_socks);
 	rcu_read_unlock();
 
-	/*
-	 * Unlike other sk lookup places we do not check
+	/* Conflicts with an existing IPV6_ADDR_ANY (if ipv6) or INADDR_ANY (if
+	 * ipv4) should have been checked already. We need to do these two
+	 * checks separately because their spinlocks have to be acquired/released
+	 * independently of each other, to prevent possible deadlocks
+	 */
+	if (inet_use_bhash2_on_bind(sk))
+		return tb2 && inet_bhash2_conflict(sk, tb2, uid, relax,
+						   reuseport_cb_ok, reuseport_ok);
+
+	/* Unlike other sk lookup places we do not check
 	 * for sk_net here, since _all_ the socks listed
 	 * in tb->owners and tb2->owners list belong
 	 * to the same net - the one this bucket belongs to.
 	 */
+	sk_for_each_bound(sk2, &tb->owners) {
+		if (!inet_bind_conflict(sk, sk2, uid, relax, reuseport_cb_ok, reuseport_ok))
+			continue;
 
-	if (!inet_use_bhash2_on_bind(sk)) {
-		struct sock *sk2;
-
-		sk_for_each_bound(sk2, &tb->owners)
-			if (inet_bind_conflict(sk, sk2, uid, relax,
-					       reuseport_cb_ok, reuseport_ok) &&
-			    inet_rcv_saddr_equal(sk, sk2, true))
-				return true;
-
-		return false;
+		if (inet_rcv_saddr_equal(sk, sk2, true))
+			return true;
 	}
 
-	/* Conflicts with an existing IPV6_ADDR_ANY (if ipv6) or INADDR_ANY (if
-	 * ipv4) should have been checked already. We need to do these two
-	 * checks separately because their spinlocks have to be acquired/released
-	 * independently of each other, to prevent possible deadlocks
-	 */
-	return tb2 && inet_bhash2_conflict(sk, tb2, uid, relax, reuseport_cb_ok,
-					   reuseport_ok);
+	return false;
 }
 
 /* Determine if there is a bind conflict with an existing IPV6_ADDR_ANY (if ipv6) or