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Commit 7068b7a1 authored by John Stultz's avatar John Stultz
Browse files

timers: Remove delayed irqwork from alarmtimers implementation 



Thomas asked about the delayed irq work in the alarmtimers code,
and I realized that it was a legacy from when the alarmtimer base
lock was a mutex (due to concerns that we'd be interacting with
the RTC device, which is protected by mutexes).

Since the alarmtimer base is now protected by a spinlock, we can
simply execute alarmtimer functions directly from the hrtimer
callback. Should any future alarmtimer functions sleep, they can
simply manage scheduling any delayed work themselves.

CC: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
parent 180bf812

kernel/time/alarmtimer.c

+9 −23
Original line number Diff line number Diff line
@@ -33,7 +33,6 @@ 
 * @timer: 		hrtimer used to schedule events while running

 * @gettime:		Function to read the time correlating to the base

 * @base_clockid:	clockid for the base

 * @irqwork		Delayed work structure for expiring timers

 */

static struct alarm_base {

	spinlock_t		lock;
@@ -41,7 +40,6 @@ static struct alarm_base { 
	struct hrtimer		timer;

	ktime_t			(*gettime)(void);

	clockid_t		base_clockid;

	struct work_struct	irqwork;

} alarm_bases[ALARM_NUMTYPE];



/* rtc timer and device for setting alarm wakeups at suspend */
@@ -97,22 +95,23 @@ static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm) 
	}

}





/**

 * alarmtimer_do_work - Handles alarm being fired.

 * @work: pointer to workqueue being run

 * alarmtimer_fired - Handles alarm hrtimer being fired.

 * @timer: pointer to hrtimer being run

 *

 * When a alarm timer fires, this runs through the timerqueue to

 * see which alarms expired, and runs those. If there are more alarm

 * timers queued for the future, we set the hrtimer to fire when

 * when the next future alarm timer expires.

 */

static void alarmtimer_do_work(struct work_struct *work)

static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)

{

	struct alarm_base *base = container_of(work, struct alarm_base,

						irqwork);

	struct alarm_base *base = container_of(timer, struct alarm_base, timer);

	struct timerqueue_node *next;

	unsigned long flags;

	ktime_t now;

	int ret = HRTIMER_NORESTART;



	spin_lock_irqsave(&base->lock, flags);

	now = base->gettime();
@@ -140,25 +139,13 @@ static void alarmtimer_do_work(struct work_struct *work) 
	}



	if (next) {

		hrtimer_start(&base->timer, next->expires,

				HRTIMER_MODE_ABS);

		hrtimer_set_expires(&base->timer, next->expires);

		ret = HRTIMER_RESTART;

	}

	spin_unlock_irqrestore(&base->lock, flags);

}



	return ret;



/**

 * alarmtimer_fired - Handles alarm hrtimer being fired.

 * @timer: pointer to hrtimer being run

 *

 * When a timer fires, this schedules the do_work function to

 * be run.

 */

static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer)

{

	struct alarm_base *base = container_of(timer, struct alarm_base, timer);

	schedule_work(&base->irqwork);

	return HRTIMER_NORESTART;

}
@@ -636,7 +623,6 @@ static int __init alarmtimer_init(void) 
				alarm_bases[i].base_clockid,

				HRTIMER_MODE_ABS);

		alarm_bases[i].timer.function = alarmtimer_fired;

		INIT_WORK(&alarm_bases[i].irqwork, alarmtimer_do_work);

	}

	error = platform_driver_register(&alarmtimer_driver);

	platform_device_register_simple("alarmtimer", -1, NULL, 0);