struct workqueue_struct *__create_workqueue_key(const char *name, int singlethread, int freezeable, int rt, struct lock_class_key *key, const char *lock_name) { struct workqueue_struct *wq; struct cpu_workqueue_struct *cwq; int err = 0, cpu; /*分配wq结构*/ wq = kzalloc(sizeof(*wq), GFP_KERNEL); if (!wq) return NULL; /*分配cwq结构*/ wq->cpu_wq = alloc_percpu(struct cpu_workqueue_struct); if (!wq->cpu_wq) { kfree(wq); return NULL; } wq->name = name; lockdep_init_map(&wq->lockdep_map, lock_name, key, 0); wq->singlethread = singlethread; wq->freezeable = freezeable; wq->rt = rt; INIT_LIST_HEAD(&wq->list); if (singlethread) {/*如果设置了单线程，只创建一个*/ /*初始化cwq*/ cwq = init_cpu_workqueue(wq, singlethread_cpu); /*创建内核线程*/ err = create_workqueue_thread(cwq, singlethread_cpu); /*唤醒刚创建的内核线程*/ start_workqueue_thread(cwq, -1); } else {/*反之，每个cpu创建一个线程*/ cpu_maps_update_begin(); /* * We must place this wq on list even if the code below fails. * cpu_down(cpu) can remove cpu from cpu_populated_map before * destroy_workqueue() takes the lock, in that case we leak * cwq[cpu]->thread. */ spin_lock(&workqueue_lock); list_add(&wq->list, &workqueues); spin_unlock(&workqueue_lock); /* * We must initialize cwqs for each possible cpu even if we * are going to call destroy_workqueue() finally. Otherwise * cpu_up() can hit the uninitialized cwq once we drop the * lock. */ for_each_possible_cpu(cpu) {/*对每个cpu*/ cwq = init_cpu_workqueue(wq, cpu); if (err || !cpu_online(cpu)) continue; err = create_workqueue_thread(cwq, cpu); start_workqueue_thread(cwq, cpu); } cpu_maps_update_done(); } if (err) { destroy_workqueue(wq); wq = NULL; } return wq; }