TF_NOPUSH
tp->t_flags = intotcpcb(listeninp)->t_flags & (TF_NOPUSH|TF_NODELAY);
(tp->t_flags & TF_NOPUSH) == 0)
tp->t_flags |= TF_NOPUSH;
else if (tp->t_flags & TF_NOPUSH) {
tp->t_flags &= ~TF_NOPUSH;
*mtod(m, int *) = tp->t_flags & TF_NOPUSH;