inet: fix improper empty comparison

When doing my reuseport rework I screwed up and changed a

if (hlist_empty(&tb->owners))

to

if (!hlist_empty(&tb->owners))

This is obviously bad as all of the reuseport/reuse logic was reversed,
which caused weird problems like allowing an ipv4 bind conflict if we
opened an ipv4 only socket on a port followed by an ipv6 only socket on
the same port.

Fixes: b9470c2 ("inet: kill smallest_size and smallest_port")
Reported-by: Cole Robinson <crobinso@redhat.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/inet_connection_sock.c

@@ -321,7 +321,7 @@ int inet_csk_get_port(struct sock *sk, unsigned short snum)
 			goto fail_unlock;
 	}
 success:
-	if (!hlist_empty(&tb->owners)) {
+	if (hlist_empty(&tb->owners)) {
 		tb->fastreuse = reuse;
 		if (sk->sk_reuseport) {
 			tb->fastreuseport = FASTREUSEPORT_ANY;