From 59a93c27c4892f04dfd8f91f8b64d0d6eae43e6e Mon Sep 17 00:00:00 2001 From: Todd Poynor Date: Thu, 9 Aug 2012 00:37:27 -0700 Subject: alarmtimer: Implement minimum alarm interval for allowing suspend alarmtimer suspend return -EBUSY if the next alarm will fire in less than 2 seconds. This allows one RTC seconds tick to occur subsequent to this check before the alarm wakeup time is set, ensuring the wakeup time is still in the future (assuming the RTC does not tick one more second prior to setting the alarm). If suspend is rejected due to an imminent alarm, hold a wakeup source for 2 seconds to process the alarm prior to reattempting suspend. If setting the alarm incurs an -ETIME for an alarm set in the past, or any other problem setting the alarm, abort suspend and hold a wakelock for 1 second while the alarm is allowed to be serviced or other hopefully transient conditions preventing the alarm clear up. Signed-off-by: Todd Poynor Signed-off-by: John Stultz --- kernel/time/alarmtimer.c | 18 +++++++++++++----- 1 file changed, 13 insertions(+), 5 deletions(-) (limited to 'kernel/time') diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index aa27d391bfc8..54e7145c5414 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -46,6 +46,8 @@ static struct alarm_base { static ktime_t freezer_delta; static DEFINE_SPINLOCK(freezer_delta_lock); +static struct wakeup_source *ws; + #ifdef CONFIG_RTC_CLASS /* rtc timer and device for setting alarm wakeups at suspend */ static struct rtc_timer rtctimer; @@ -250,6 +252,7 @@ static int alarmtimer_suspend(struct device *dev) unsigned long flags; struct rtc_device *rtc; int i; + int ret; spin_lock_irqsave(&freezer_delta_lock, flags); min = freezer_delta; @@ -279,8 +282,10 @@ static int alarmtimer_suspend(struct device *dev) if (min.tv64 == 0) return 0; - /* XXX - Should we enforce a minimum sleep time? */ - WARN_ON(min.tv64 < NSEC_PER_SEC); + if (ktime_to_ns(min) < 2 * NSEC_PER_SEC) { + __pm_wakeup_event(ws, 2 * MSEC_PER_SEC); + return -EBUSY; + } /* Setup an rtc timer to fire that far in the future */ rtc_timer_cancel(rtc, &rtctimer); @@ -288,9 +293,11 @@ static int alarmtimer_suspend(struct device *dev) now = rtc_tm_to_ktime(tm); now = ktime_add(now, min); - rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0)); - - return 0; + /* Set alarm, if in the past reject suspend briefly to handle */ + ret = rtc_timer_start(rtc, &rtctimer, now, ktime_set(0, 0)); + if (ret < 0) + __pm_wakeup_event(ws, MSEC_PER_SEC); + return ret; } #else static int alarmtimer_suspend(struct device *dev) @@ -821,6 +828,7 @@ static int __init alarmtimer_init(void) error = PTR_ERR(pdev); goto out_drv; } + ws = wakeup_source_register("alarmtimer"); return 0; out_drv: -- cgit v1.2.3 From dae373be9fec6f850159a05af3a1c36236a70d43 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Thu, 13 Sep 2012 19:12:16 -0400 Subject: alarmtimer: Use hrtimer per-alarm instead of per-base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Arve Hjønnevåg reported numerous crashes from the "BUG_ON(timer->state != HRTIMER_STATE_CALLBACK)" check in __run_hrtimer after it called alarmtimer_fired. It ends up the alarmtimer code was not properly handling possible failures of hrtimer_try_to_cancel, and because these faulres occur when the underlying base hrtimer is being run, this limits the ability to properly handle modifications to any alarmtimers on that base. Because much of the logic duplicates the hrtimer logic, it seems that we might as well have a per-alarmtimer hrtimer, and avoid the extra complextity of trying to multiplex many alarmtimers off of one hrtimer. Thus this patch moves the hrtimer to the alarm structure and simplifies the management logic. Changelog: v2: * Includes a fix for double alarm_start calls found by Arve Cc: Arve Hjønnevåg Cc: Colin Cross Cc: Thomas Gleixner Reported-by: Arve Hjønnevåg Tested-by: Arve Hjønnevåg Signed-off-by: John Stultz --- include/linux/alarmtimer.h | 3 +- kernel/time/alarmtimer.c | 94 +++++++++++++--------------------------------- 2 files changed, 29 insertions(+), 68 deletions(-) (limited to 'kernel/time') diff --git a/include/linux/alarmtimer.h b/include/linux/alarmtimer.h index 96c5c249b086..f122c9fbf8c7 100644 --- a/include/linux/alarmtimer.h +++ b/include/linux/alarmtimer.h @@ -35,6 +35,7 @@ enum alarmtimer_restart { */ struct alarm { struct timerqueue_node node; + struct hrtimer timer; enum alarmtimer_restart (*function)(struct alarm *, ktime_t now); enum alarmtimer_type type; int state; @@ -43,7 +44,7 @@ struct alarm { void alarm_init(struct alarm *alarm, enum alarmtimer_type type, enum alarmtimer_restart (*function)(struct alarm *, ktime_t)); -void alarm_start(struct alarm *alarm, ktime_t start); +int alarm_start(struct alarm *alarm, ktime_t start); int alarm_try_to_cancel(struct alarm *alarm); int alarm_cancel(struct alarm *alarm); diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index 54e7145c5414..b1560ebe759f 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -37,7 +37,6 @@ static struct alarm_base { spinlock_t lock; struct timerqueue_head timerqueue; - struct hrtimer timer; ktime_t (*gettime)(void); clockid_t base_clockid; } alarm_bases[ALARM_NUMTYPE]; @@ -132,21 +131,17 @@ static inline void alarmtimer_rtc_timer_init(void) { } * @base: pointer to the base where the timer is being run * @alarm: pointer to alarm being enqueued. * - * Adds alarm to a alarm_base timerqueue and if necessary sets - * an hrtimer to run. + * Adds alarm to a alarm_base timerqueue * * Must hold base->lock when calling. */ static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm) { + if (alarm->state & ALARMTIMER_STATE_ENQUEUED) + timerqueue_del(&base->timerqueue, &alarm->node); + timerqueue_add(&base->timerqueue, &alarm->node); alarm->state |= ALARMTIMER_STATE_ENQUEUED; - - if (&alarm->node == timerqueue_getnext(&base->timerqueue)) { - hrtimer_try_to_cancel(&base->timer); - hrtimer_start(&base->timer, alarm->node.expires, - HRTIMER_MODE_ABS); - } } /** @@ -154,28 +149,17 @@ static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm) * @base: pointer to the base where the timer is running * @alarm: pointer to alarm being removed * - * Removes alarm to a alarm_base timerqueue and if necessary sets - * a new timer to run. + * Removes alarm to a alarm_base timerqueue * * Must hold base->lock when calling. */ static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm) { - struct timerqueue_node *next = timerqueue_getnext(&base->timerqueue); - if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED)) return; timerqueue_del(&base->timerqueue, &alarm->node); alarm->state &= ~ALARMTIMER_STATE_ENQUEUED; - - if (next == &alarm->node) { - hrtimer_try_to_cancel(&base->timer); - next = timerqueue_getnext(&base->timerqueue); - if (!next) - return; - hrtimer_start(&base->timer, next->expires, HRTIMER_MODE_ABS); - } } @@ -190,42 +174,23 @@ static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm) */ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer) { - struct alarm_base *base = container_of(timer, struct alarm_base, timer); - struct timerqueue_node *next; + struct alarm *alarm = container_of(timer, struct alarm, timer); + struct alarm_base *base = &alarm_bases[alarm->type]; unsigned long flags; - ktime_t now; int ret = HRTIMER_NORESTART; int restart = ALARMTIMER_NORESTART; spin_lock_irqsave(&base->lock, flags); - now = base->gettime(); - while ((next = timerqueue_getnext(&base->timerqueue))) { - struct alarm *alarm; - ktime_t expired = next->expires; - - if (expired.tv64 > now.tv64) - break; - - alarm = container_of(next, struct alarm, node); - - timerqueue_del(&base->timerqueue, &alarm->node); - alarm->state &= ~ALARMTIMER_STATE_ENQUEUED; - - alarm->state |= ALARMTIMER_STATE_CALLBACK; - spin_unlock_irqrestore(&base->lock, flags); - if (alarm->function) - restart = alarm->function(alarm, now); - spin_lock_irqsave(&base->lock, flags); - alarm->state &= ~ALARMTIMER_STATE_CALLBACK; + alarmtimer_remove(base, alarm); + spin_unlock_irqrestore(&base->lock, flags); - if (restart != ALARMTIMER_NORESTART) { - timerqueue_add(&base->timerqueue, &alarm->node); - alarm->state |= ALARMTIMER_STATE_ENQUEUED; - } - } + if (alarm->function) + restart = alarm->function(alarm, base->gettime()); - if (next) { - hrtimer_set_expires(&base->timer, next->expires); + spin_lock_irqsave(&base->lock, flags); + if (restart != ALARMTIMER_NORESTART) { + hrtimer_set_expires(&alarm->timer, alarm->node.expires); + alarmtimer_enqueue(base, alarm); ret = HRTIMER_RESTART; } spin_unlock_irqrestore(&base->lock, flags); @@ -331,6 +296,9 @@ void alarm_init(struct alarm *alarm, enum alarmtimer_type type, enum alarmtimer_restart (*function)(struct alarm *, ktime_t)) { timerqueue_init(&alarm->node); + hrtimer_init(&alarm->timer, alarm_bases[type].base_clockid, + HRTIMER_MODE_ABS); + alarm->timer.function = alarmtimer_fired; alarm->function = function; alarm->type = type; alarm->state = ALARMTIMER_STATE_INACTIVE; @@ -341,17 +309,19 @@ void alarm_init(struct alarm *alarm, enum alarmtimer_type type, * @alarm: ptr to alarm to set * @start: time to run the alarm */ -void alarm_start(struct alarm *alarm, ktime_t start) +int alarm_start(struct alarm *alarm, ktime_t start) { struct alarm_base *base = &alarm_bases[alarm->type]; unsigned long flags; + int ret; spin_lock_irqsave(&base->lock, flags); - if (alarmtimer_active(alarm)) - alarmtimer_remove(base, alarm); alarm->node.expires = start; alarmtimer_enqueue(base, alarm); + ret = hrtimer_start(&alarm->timer, alarm->node.expires, + HRTIMER_MODE_ABS); spin_unlock_irqrestore(&base->lock, flags); + return ret; } /** @@ -365,18 +335,12 @@ int alarm_try_to_cancel(struct alarm *alarm) { struct alarm_base *base = &alarm_bases[alarm->type]; unsigned long flags; - int ret = -1; - spin_lock_irqsave(&base->lock, flags); - - if (alarmtimer_callback_running(alarm)) - goto out; + int ret; - if (alarmtimer_is_queued(alarm)) { + spin_lock_irqsave(&base->lock, flags); + ret = hrtimer_try_to_cancel(&alarm->timer); + if (ret >= 0) alarmtimer_remove(base, alarm); - ret = 1; - } else - ret = 0; -out: spin_unlock_irqrestore(&base->lock, flags); return ret; } @@ -809,10 +773,6 @@ static int __init alarmtimer_init(void) for (i = 0; i < ALARM_NUMTYPE; i++) { timerqueue_init_head(&alarm_bases[i].timerqueue); spin_lock_init(&alarm_bases[i].lock); - hrtimer_init(&alarm_bases[i].timer, - alarm_bases[i].base_clockid, - HRTIMER_MODE_ABS); - alarm_bases[i].timer.function = alarmtimer_fired; } error = alarmtimer_rtc_interface_setup(); -- cgit v1.2.3 From a65bcc12ad74b3efe78847945a1e36cfcbcbc4e6 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Thu, 13 Sep 2012 19:25:22 -0400 Subject: alarmtimer: Rename alarmtimer_remove to alarmtimer_dequeue MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Now that alarmtimer_remove has been simplified, change its name to _dequeue to better match its paired _enqueue function. Cc: Arve Hjønnevåg Cc: Colin Cross Cc: Thomas Gleixner Signed-off-by: John Stultz --- kernel/time/alarmtimer.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'kernel/time') diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index b1560ebe759f..f11d83b12949 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -145,7 +145,7 @@ static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm) } /** - * alarmtimer_remove - Removes an alarm timer from an alarm_base timerqueue + * alarmtimer_dequeue - Removes an alarm timer from an alarm_base timerqueue * @base: pointer to the base where the timer is running * @alarm: pointer to alarm being removed * @@ -153,7 +153,7 @@ static void alarmtimer_enqueue(struct alarm_base *base, struct alarm *alarm) * * Must hold base->lock when calling. */ -static void alarmtimer_remove(struct alarm_base *base, struct alarm *alarm) +static void alarmtimer_dequeue(struct alarm_base *base, struct alarm *alarm) { if (!(alarm->state & ALARMTIMER_STATE_ENQUEUED)) return; @@ -181,7 +181,7 @@ static enum hrtimer_restart alarmtimer_fired(struct hrtimer *timer) int restart = ALARMTIMER_NORESTART; spin_lock_irqsave(&base->lock, flags); - alarmtimer_remove(base, alarm); + alarmtimer_dequeue(base, alarm); spin_unlock_irqrestore(&base->lock, flags); if (alarm->function) @@ -340,7 +340,7 @@ int alarm_try_to_cancel(struct alarm *alarm) spin_lock_irqsave(&base->lock, flags); ret = hrtimer_try_to_cancel(&alarm->timer); if (ret >= 0) - alarmtimer_remove(base, alarm); + alarmtimer_dequeue(base, alarm); spin_unlock_irqrestore(&base->lock, flags); return ret; } -- cgit v1.2.3 From b3c869d35b9b014f63ac0beacd31c57372084d01 Mon Sep 17 00:00:00 2001 From: John Stultz Date: Tue, 4 Sep 2012 12:42:27 -0400 Subject: jiffies: Remove compile time assumptions about CLOCK_TICK_RATE CLOCK_TICK_RATE is used to accurately caclulate exactly how a tick will be at a given HZ. This is useful, because while we'd expect NSEC_PER_SEC/HZ, the underlying hardware will have some granularity limit, so we won't be able to have exactly HZ ticks per second. This slight error can cause timekeeping quality problems when using the jiffies or other jiffies driven clocksources. Thus we currently use compile time CLOCK_TICK_RATE value to generate SHIFTED_HZ and NSEC_PER_JIFFIES, which we then use to adjust the jiffies clocksource to correct this error. Unfortunately though, since CLOCK_TICK_RATE is a compile time value, and the jiffies clocksource is registered very early during boot, there are a number of cases where there are different possible hardware timers that have different tick rates. This causes problems in cases like ARM where there are numerous different types of hardware, each having their own compile-time CLOCK_TICK_RATE, making it hard to accurately support different hardware with a single kernel. For the most part, this doesn't matter all that much, as not too many systems actually utilize the jiffies or jiffies driven clocksource. Usually there are other highres clocksources who's granularity error is negligable. Even so, we have some complicated calcualtions that we do everywhere to handle these edge cases. This patch removes the compile time SHIFTED_HZ value, and introduces a register_refined_jiffies() function. This results in the default jiffies clock as being assumed a perfect HZ freq, and allows archtectures that care about jiffies accuracy to call register_refined_jiffies() with the tick rate, specified dynamically at boot. This allows us, where necessary, to not have a compile time CLOCK_TICK_RATE constant, simplifies the jiffies code, and still provides a way to have an accurate jiffies clock. NOTE: Since this patch does not add register_refinied_jiffies() calls for every arch, it may cause time quality regressions in some cases. Its likely these will not be noticable, but if they are an issue, adding the following to the end of setup_arch() should resolve the regression: register_refinied_jiffies(CLOCK_TICK_RATE) Cc: Catalin Marinas Cc: Arnd Bergmann Cc: Richard Cochran Cc: Prarit Bhargava Cc: Thomas Gleixner Signed-off-by: John Stultz --- arch/x86/kernel/setup.c | 3 +++ include/linux/jiffies.h | 15 ++------------- kernel/time/jiffies.c | 32 +++++++++++++++++++++++++++++++- 3 files changed, 36 insertions(+), 14 deletions(-) (limited to 'kernel/time') diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index f4b9b80e1b95..4062f15bfbdd 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -68,6 +68,7 @@ #include #include #include +#include #include