TUN_RWAIT
tp->tun_flags &= ~TUN_RWAIT;
tp->tun_flags |= TUN_RWAIT;
if (tp->tun_flags & TUN_RWAIT) {
tp->tun_flags &= ~TUN_RWAIT;
if (tp->tun_flags & TUN_RWAIT) {
tp->tun_flags &= ~TUN_RWAIT;