diff options
| -rw-r--r-- | kernel/time/clocksource.c | 97 |
1 files changed, 69 insertions, 28 deletions
diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c index 89a7b91bfbd..56aaa749645 100644 --- a/kernel/time/clocksource.c +++ b/kernel/time/clocksource.c @@ -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 /** |