Re: [PATCH 0/5 v2] Fixes for leapsecond expiring early ABS_TIME CLOCK_REALTIME timers

[Prarit Bhargava]

On 06/11/2015 06:54 PM, John Stultz wrote:
> So this is a second round at trying to address the issue, trying
> to integrate feedback from Ingo and Thomas, trying to simplify
> what I can. I've also split out the changes so each can be
> more easily reviewed. Its still not tiny, but its simpler.
> 
> This series is against tip/timers/core, and the first patch isn't
> strictly related but is a fix that is needed in tip/timers/core.
> 
> As Prarit reported here:
> https://lkml.org/lkml/2015/5/27/458
> 
> Since the leapsecond is applied at timer tick time, and not
> the actual second edge, ABS_TIME CLOCK_REALTIME timers set for
> right after the leapsecond could fire a second early, since
> some timers may be expired before we trigger the timekeeping
> timer, which then applies the leapsecond.
> 
> Thus this patch series tries to address this issue, including
> extending the leap-a-day test to catch this problem, as well
> as other relevant fixups I found while working on the code.
> 
> This series has only had limited testing, so I wanted to send
> it out for initial review and comment. Folks can grab this tree
> via git for testing here:
> https://git.linaro.org/people/john.stultz/linux.git dev/early-leap-timer
> 

I'm testing this on a few more large CPU count systems.  So far, so good ...

P.

> Thoughts and feedback would be appreciated!
> thanks
> -john
> 
> Cc: Prarit Bhargava <prarit@xxxxxxxxxx>
> Cc: Daniel Bristot de Oliveira <bristot@xxxxxxxxxx>
> Cc: Richard Cochran <richardcochran@xxxxxxxxx>
> Cc: Jan Kara <jack@xxxxxxx>
> Cc: Jiri Bohac <jbohac@xxxxxxx>
> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> Cc: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
> 
> 
> John Stultz (5):
>   time: Move clock_was_set_seq update to before we update the
>     shadow-timekeeper
>   ntp: Introduce and use SECS_PER_DAY macro instead of 86400
>   time: Do leapsecond adjustment to avoid early timer expirations
>   ntp: Do leapsecond adjustment in adjtimex read path
>   selftests: timers: Add leap-second timer edge testing to leap-a-day.c
> 
>  include/linux/time64.h                      |  1 +
>  include/linux/timekeeper_internal.h         |  2 +
>  kernel/time/ntp.c                           | 61 ++++++++++++++++++++---
>  kernel/time/ntp_internal.h                  |  1 +
>  kernel/time/timekeeping.c                   | 35 +++++++++++--
>  tools/testing/selftests/timers/leap-a-day.c | 76 +++++++++++++++++++++++++++--
>  6 files changed, 160 insertions(+), 16 deletions(-)
> 
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