P_WAITED
(p->p_flags & P_WAITED) == 0 &&
(p->p_flags & P_WAITED) != 0 ||
p->p_flags |= P_WAITED;
p->p_flags &= ~P_WAITED;
p->p_flags &= ~P_WAITED;
(p->p_flags & P_WAITED) == 0) {
p->p_flags &= ~(P_TRACED | P_WAITED);
p->p_flags &= ~P_WAITED; /* XXX ? */