wakelock锁

最新推荐文章于 2023-10-12 18:16:30 发布

小小小小小小小小熊

最新推荐文章于 2023-10-12 18:16:30 发布

阅读量2.7k

点赞数

CC 4.0 BY-SA版权

分类专栏： android/linux内核操作系统电源管理

本文链接：https://blog.youkuaiyun.com/lixiaojie1012/article/details/44264583

本文详细介绍了Android内核中的Wakelock接口，包括初始化、销毁、投票反对睡眠、投超时锁、释放锁以及检查锁状态等功能。通过wakelock，系统可以防止设备在特定任务执行时进入休眠状态，确保任务的连续性。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

android的内核版本中，提供了一套阻止系统进入睡眠的wakelock接口，该套接口共有6个；

struct wake_lock{
	struct wakeup_source ws;
};
static inline void wake_lock_init(struct wake_lock *lock,int type,const char* name)
{
	wakeup_source_init(&lock->ws,name);
}
static inline void wake_lock_destroy(struct wake_lock* lock)
{
	wakeup_source_trash(&lock->ws);
}
static inline void wake_lock(struct wake_lock* lock)
{
	__pm_stay_awake(&lock->ws);
}
static inline void wake_lock_timeout(struct wake_lock* lock,long timeout)
{
	__pm_stay_awake(&lock->ws);
}
static inline void wake_unlock(struct wake_lock* lock)
{
	__pm_relax(&lock->ws);
}
static inline bool wake_lock_active(struct wake_lock* lock)
{
	return lock->ws.active;
}

还有一个重要的数据结构需要亮一下，那就是wakeup_source，该数据结构完成wakelock锁的基本控制

/**
 * struct wakeup_source - Representation of wakeup sources
 *
 * @total_time: Total time this wakeup source has been active.
 * @max_time: Maximum time this wakeup source has been continuously active.
 * @last_time: Monotonic clock when the wakeup source's was touched last time.
 * @prevent_sleep_time: Total time this source has been preventing autosleep.
 * @event_count: Number of signaled wakeup events.
 * @active_count: Number of times the wakeup sorce was activated.
 * @relax_count: Number of times the wakeup sorce was deactivated.
 * @expire_count: Number of times the wakeup source's timeout has expired.
 * @wakeup_count: Number of times the wakeup source might abort suspend.
 * @active: Status of the wakeup source.
 * @has_timeout: The wakeup source has been activated with a timeout.
 */
struct wakeup_source {
	const char 		*name;
	struct list_head	entry;
	spinlock_t		lock;
	struct timer_list	timer;
	unsigned long		timer_expires;
	ktime_t total_time;
	ktime_t max_time;
	ktime_t last_time;
	ktime_t start_prevent_time;
	ktime_t prevent_sleep_time;
	unsigned long		event_count;
	unsigned long		active_count;
	unsigned long		relax_count;
	unsigned long		expire_count;
	unsigned long		wakeup_count;
	bool			active: