3.16.54-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Colin Ian King colin.king@canonical.com
commit 2b2f5ff00f63847d95adad6289bd8b05f5983dd5 upstream.
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 Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/rtc/interface.c | 16 +++++++++++++++- 1 file changed, 15 insertions(+), 1 deletion(-)
--- a/drivers/rtc/interface.c +++ b/drivers/rtc/interface.c @@ -778,9 +778,23 @@ 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);