11     x->done = 0;  in completion_init()
25     if (x->done != COMPLETE_ALL)  in complete()
26         ++(x->done);  in complete()
41     x->done = COMPLETE_ALL; // 永久赋值  in complete_all()
59     if (!x->done)  in __wait_for_common()
63         while (!x->done && timeout > 0)  in __wait_for_common()
75         if (!x->done)  in __wait_for_common()
82     if (x->done != COMPLETE_ALL)  in __wait_for_common()
83         --(x->done);  in __wait_for_common()
153     if (!READ_ONCE(x->done))  in try_wait_for_completion()
159     if (!x->done)  in try_wait_for_completion()
161     else if (x->done != COMPLETE_ALL)  in try_wait_for_completion()
162         --(x->done);  in try_wait_for_completion()
178     if (!READ_ONCE(x->done))  in completion_done()
184     if (!READ_ONCE(x->done))  in completion_done()