RTC: Avoid races between RTC alarm wakeup and suspend. (7523ceed) · Commits · 戴 / test

If an RTC alarm fires just as suspend is happening, it is possible for suspend to complete and the alarm to be missed. To avoid the race, we must register the event with the PM core. As the event is made visible to userspace through a thread which is only scheduled by the interrupt, we need a pm_stay_awake/pm_relax pair preventing suspend from the interrupt until the thread completes its work. This makes the pm_wakeup_event() call in cmos_interrupt unnecessary as it provides suspend protection for all RTCs that use rtc_update_irq. Signed-off-by:

NeilBrown <neilb@suse.de> Signed-off-by:

Rafael J. Wysocki <rjw@sisk.pl>

drivers/rtc/interface.c

+2 −0

Original line number	Diff line number	Diff line
		@@ -582,6 +582,7 @@ enum hrtimer_restart rtc_pie_update_irq(struct hrtimer *timer)
		void rtc_update_irq(struct rtc_device *rtc,
		unsigned long num, unsigned long events)
		{
		pm_stay_awake(rtc->dev.parent);
		schedule_work(&rtc->irqwork);
		}
		EXPORT_SYMBOL_GPL(rtc_update_irq);
		@@ -844,6 +845,7 @@ void rtc_timer_do_work(struct work_struct *work)

		mutex_lock(&rtc->ops_lock);
		again:
		pm_relax(rtc->dev.parent);
		__rtc_read_time(rtc, &tm);
		now = rtc_tm_to_ktime(tm);
		while ((next = timerqueue_getnext(&rtc->timerqueue))) {

drivers/rtc/rtc-cmos.c

+0 −1

Original line number	Diff line number	Diff line
		@@ -568,7 +568,6 @@ static irqreturn_t cmos_interrupt(int irq, void *p)
		hpet_mask_rtc_irq_bit(RTC_AIE);

		CMOS_READ(RTC_INTR_FLAGS);
		pm_wakeup_event(cmos_rtc.dev, 0);
		}
		spin_unlock(&rtc_lock);

Admin message