SIGNAL_UNKILLABLE
current->signal->flags & SIGNAL_UNKILLABLE)
p->signal->flags |= SIGNAL_UNKILLABLE;
t->signal->flags &= ~SIGNAL_UNKILLABLE;
if (unlikely(signal->flags & SIGNAL_UNKILLABLE) &&
if (unlikely(t->signal->flags & SIGNAL_UNKILLABLE) &&