/*
 * Tell a process that it has a new active signal..
 *
 * NOTE! we rely on the previous spin_lock to
 * lock interrupts for us! We can only be called with
 * "siglock" held, and the local interrupt must
 * have been disabled when that got acquired!
 *
 * No need to set need_resched since signal event passing
 * goes through ->blocked
 */
void signal_wake_up(struct task_struct *t, int resume)
{
 unsigned int mask;

 set_tsk_thread_flag(t, TIF_SIGPENDING);//为进程设置TIF_SIGPENDING标志

 /*
  * For SIGKILL, we want to wake it up in the stopped/traced case.
  * We don't check t->state here because there is a race with it
  * executing another processor and just now entering stopped state.
  * By using wake_up_state, we ensure the process will wake up and
  * handle its death signal.
  */
 mask = TASK_INTERRUPTIBLE;
 if (resume)
  mask |= TASK_STOPPED | TASK_TRACED;
 if (!wake_up_state(t, mask))
  kick_process(t);
}