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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: John Stultz <john.stultz@linaro.org>
This commit is contained in:
John Stultz 2011-04-28 13:29:18 -07:00
parent 180bf812ce
commit 7068b7a162
1 changed files with 9 additions and 23 deletions
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32
kernel/time/alarmtimer.c
View File

@ -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);