Re: [PATCH] hrtimer, add expiry time overflow check in hrtimer_interrupt

Guenter Roeck
2013-04-25T04:49:20Z

On Thu, Apr 25, 2013 at 09:38:22AM +0800, Li Zefan wrote:
> On 2013/4/25 6:42, Guenter Roeck wrote:
> > On Mon, Apr 08, 2013 at 04:34:26PM -0400, Prarit Bhargava wrote:
> >>
> >>
> >> On 04/08/2013 04:19 PM, John Stultz wrote:
> >>> On 04/08/2013 05:47 AM, Prarit Bhargava wrote:
> >>
> >>>>
> >>>> A simple check for an overflow can resolve this problem. Using KTIME_MAX
> >>>> instead of the overflow value will result in the hrtimer function being run,
> >>>> and the reprogramming of the timer after that.
> >>>>
> >>>> Signed-off-by: Prarit Bhargava <prarit@redhat.com>
> >>>> Cc: Thomas Gleixner <tglx@linutronix.de>
> >>>> Cc: John Stultz <john.stultz@linaro.org>
> >>>
> >>> Prarit: Should this be tagged for -stable?
> >>
> >> John,
> >>
> >> Yes, this should go to -stable. cc'd.
> >>
> > Hi,
> >
> > I am a bit surprised that this patch has not found its way into mainline yet,
> > as everyone seems to agree that it is a candidate for -stable.
> >
> > I hit this problem very reliably (ie with each boot) with 3.8.x on systems
> > which have no RTC and run systemd. Seen with Freescale P5040 as well as
> > a Broadcom MIPS based system.
> >
>
> FYI, we also hit this warning with 3.4-rt.
>
You are lucky if it is just a warning for you. In my case the system is
reliably dead. Guess there are not (yet) many users out there using
systemd (or something similar) on a system with no RTC.

While I am not too happy about the delay to get the patch integrated,
I am glad that Prarit found and fixed the problem. Saved me a lot of time.

Guenter