Commit 2b2f5ff0 authored May 16, 2016 by Colin Ian King Committed by Alexandre Belloni Jun 04, 2016

rtc: interface: ignore expired timers when enqueuing new timers

This patch fixes a RTC wakealarm issue, namely, the event fires during
hibernate and is not cleared from the list, causing hwclock to block.

The current enqueuing does not trigger an alarm if any expired timers
already exist on the timerqueue. This can occur when a RTC wake alarm
is used to wake a machine out of hibernate and the resumed state has
old expired timers that have not been removed from the timer queue.
This fix skips over any expired timers and triggers an alarm if there
are no pending timers on the timerqueue. Note that the skipped expired
timer will get reaped later on, so there is no need to clean it up
immediately.

The issue can be reproduced by putting a machine into hibernate and
waking it with the RTC wakealarm.  Running the example RTC test program
from tools/testing/selftests/timers/rtctest.c after the hibernate will
block indefinitely.  With the fix, it no longer blocks after the
hibernate resume.

BugLink: http://bugs.launchpad.net/bugs/1333569



Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>

parent 279da149

drivers/rtc/interface.c

+15 −1

Original line number	Diff line number	Diff line
		@@ -758,9 +758,23 @@ EXPORT_SYMBOL_GPL(rtc_irq_set_freq);
		*/
		static int rtc_timer_enqueue(struct rtc_device rtc, struct rtc_timer timer)
		{
		struct timerqueue_node *next = timerqueue_getnext(&rtc->timerqueue);
		struct rtc_time tm;
		ktime_t now;

		timer->enabled = 1;
		__rtc_read_time(rtc, &tm);
		now = rtc_tm_to_ktime(tm);

		/* Skip over expired timers */
		while (next) {
		if (next->expires.tv64 >= now.tv64)
		break;
		next = timerqueue_iterate_next(next);
		}

		timerqueue_add(&rtc->timerqueue, &timer->node);
		if (&timer->node == timerqueue_getnext(&rtc->timerqueue)) {
		if (!next) {
		struct rtc_wkalrm alarm;
		int err;
		alarm.time = rtc_ktime_to_tm(timer->node.expires);

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