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clocksource: Refactor clocksource watchdog 

Refactor clocksource watchdog code to make it more readable. Add
clocksource_dequeue_watchdog to remove a clocksource from the watchdog
list when it is unregistered.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: John Stultz <johnstul@us.ibm.com>
Cc: Daniel Walker <dwalker@fifo99.com>
LKML-Reference: <20090814134809.110881699@de.ibm.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Martin Schwidefsky 2009-08-14 15:47:24 +02:00 committed by Thomas Gleixner
parent 0f8e8ef7c2
commit fb63a0ebe6
1 changed files with 69 additions and 28 deletions
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97
kernel/time/clocksource.c
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@ -145,6 +145,7 @@ static struct clocksource *watchdog;
static struct timer_list watchdog_timer;
static DEFINE_SPINLOCK(watchdog_lock);
static cycle_t watchdog_last;
static int watchdog_running;
/*
* Interval: 0.5sec Threshold: 0.0625s
@ -168,6 +169,8 @@ static void clocksource_watchdog(unsigned long data)
int64_t wd_nsec, cs_nsec;
spin_lock(&watchdog_lock);
if (!watchdog_running)
goto out;
wdnow = watchdog->read(watchdog);
wd_nsec = cyc2ns(watchdog, (wdnow - watchdog_last) & watchdog->mask);
@ -217,9 +220,30 @@ static void clocksource_watchdog(unsigned long data)
watchdog_timer.expires += WATCHDOG_INTERVAL;
add_timer_on(&watchdog_timer, next_cpu);
}
out:
spin_unlock(&watchdog_lock);
}
static inline void clocksource_start_watchdog(void)
{
if (watchdog_running || !watchdog || list_empty(&watchdog_list))
return;
init_timer(&watchdog_timer);
watchdog_timer.function = clocksource_watchdog;
watchdog_last = watchdog->read(watchdog);
watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask));
watchdog_running = 1;
}
static inline void clocksource_stop_watchdog(void)
{
if (!watchdog_running || (watchdog && !list_empty(&watchdog_list)))
return;
del_timer(&watchdog_timer);
watchdog_running = 0;
}
static inline void clocksource_reset_watchdog(void)
{
struct clocksource *cs;
@ -237,55 +261,70 @@ static void clocksource_resume_watchdog(void)
spin_unlock_irqrestore(&watchdog_lock, flags);
}
static void clocksource_check_watchdog(struct clocksource *cs)
static void clocksource_enqueue_watchdog(struct clocksource *cs)
{
unsigned long flags;
spin_lock_irqsave(&watchdog_lock, flags);
if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
int started = !list_empty(&watchdog_list);
/* cs is a clocksource to be watched. */
list_add(&cs->wd_list, &watchdog_list);
if (!started && watchdog) {
watchdog_last = watchdog->read(watchdog);
watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
add_timer_on(&watchdog_timer,
cpumask_first(cpu_online_mask));
}
cs->flags &= ~CLOCK_SOURCE_WATCHDOG;
} else {
/* cs is a watchdog. */
if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
/* Pick the best watchdog. */
if (!watchdog || cs->rating > watchdog->rating) {
if (watchdog)
del_timer(&watchdog_timer);
watchdog = cs;
init_timer(&watchdog_timer);
watchdog_timer.function = clocksource_watchdog;
/* Reset watchdog cycles */
clocksource_reset_watchdog();
/* Start if list is not empty */
if (!list_empty(&watchdog_list)) {
watchdog_last = watchdog->read(watchdog);
watchdog_timer.expires =
jiffies + WATCHDOG_INTERVAL;
add_timer_on(&watchdog_timer,
cpumask_first(cpu_online_mask));
}
}
}
/* Check if the watchdog timer needs to be started. */
clocksource_start_watchdog();
spin_unlock_irqrestore(&watchdog_lock, flags);
}
#else
static void clocksource_check_watchdog(struct clocksource *cs)
static void clocksource_dequeue_watchdog(struct clocksource *cs)
{
struct clocksource *tmp;
unsigned long flags;
spin_lock_irqsave(&watchdog_lock, flags);
if (cs->flags & CLOCK_SOURCE_MUST_VERIFY) {
/* cs is a watched clocksource. */
list_del_init(&cs->wd_list);
} else if (cs == watchdog) {
/* Reset watchdog cycles */
clocksource_reset_watchdog();
/* Current watchdog is removed. Find an alternative. */
watchdog = NULL;
list_for_each_entry(tmp, &clocksource_list, list) {
if (tmp == cs || tmp->flags & CLOCK_SOURCE_MUST_VERIFY)
continue;
if (!watchdog || tmp->rating > watchdog->rating)
watchdog = tmp;
}
}
cs->flags &= ~CLOCK_SOURCE_WATCHDOG;
/* Check if the watchdog timer needs to be stopped. */
clocksource_stop_watchdog();
spin_unlock_irqrestore(&watchdog_lock, flags);
}
#else /* CONFIG_CLOCKSOURCE_WATCHDOG */
static void clocksource_enqueue_watchdog(struct clocksource *cs)
{
if (cs->flags & CLOCK_SOURCE_IS_CONTINUOUS)
cs->flags |= CLOCK_SOURCE_VALID_FOR_HRES;
}
static inline void clocksource_dequeue_watchdog(struct clocksource *cs) { }
static inline void clocksource_resume_watchdog(void) { }
#endif
#endif /* CONFIG_CLOCKSOURCE_WATCHDOG */
/**
* clocksource_resume - resume the clocksource(s)
@ -414,14 +453,13 @@ int clocksource_register(struct clocksource *cs)
clocksource_enqueue(cs);
clocksource_select();
spin_unlock_irqrestore(&clocksource_lock, flags);
clocksource_check_watchdog(cs);
clocksource_enqueue_watchdog(cs);
return 0;
}
EXPORT_SYMBOL(clocksource_register);
/**
* clocksource_change_rating - Change the rating of a registered clocksource
*
*/
void clocksource_change_rating(struct clocksource *cs, int rating)
{
@ -434,6 +472,7 @@ void clocksource_change_rating(struct clocksource *cs, int rating)
clocksource_select();
spin_unlock_irqrestore(&clocksource_lock, flags);
}
EXPORT_SYMBOL(clocksource_change_rating);
/**
* clocksource_unregister - remove a registered clocksource
@ -442,11 +481,13 @@ void clocksource_unregister(struct clocksource *cs)
{
unsigned long flags;
clocksource_dequeue_watchdog(cs);
spin_lock_irqsave(&clocksource_lock, flags);
list_del(&cs->list);
clocksource_select();
spin_unlock_irqrestore(&clocksource_lock, flags);
}
EXPORT_SYMBOL(clocksource_unregister);
#ifdef CONFIG_SYSFS
/**