TF_SIGNATURE
if (tp->t_flags & TF_SIGNATURE) {
&& (tp->t_flags & TF_SIGNATURE) == 0
if (tp->t_flags & TF_SIGNATURE) {
tp->t_flags |= TF_SIGNATURE;
tp->t_flags |= TF_SIGNATURE;
tp->t_flags &= ~TF_SIGNATURE;
optval = (tp->t_flags & TF_SIGNATURE) ? 1 : 0;