[PATCH] UBUNTU: SAUCE: drivers/rtc/interface.c: ignore exprired times when enqueing new timers (LP: #1333569)

[Colin Ian King]

On 06/01/15 12:48, Colin King wrote:
> From: Colin Ian King <colin.king at canonical.com>
> 
> 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.
> 
> The bug was found running the example RTC timer program from
> Documentation/rtc.txt; it runs fine before a hibernate but will block
> forever on RTC reads after a resume from a hibernate that is woken
> up using a RTC wakealarm.

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

> 
> Signed-off-by: Colin Ian King <colin.king at canonical.com>
> ---
>  drivers/rtc/interface.c | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/rtc/interface.c b/drivers/rtc/interface.c
> index 5b2717f..ca9d9fc 100644
> --- a/drivers/rtc/interface.c
> +++ b/drivers/rtc/interface.c
> @@ -780,9 +780,23 @@ 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);
>