[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20170527073836.7rxbn5kdf5c536q5@gmail.com>
Date: Sat, 27 May 2017 09:38:36 +0200
From: Ingo Molnar <mingo@...nel.org>
To: John Stultz <john.stultz@...aro.org>
Cc: lkml <linux-kernel@...r.kernel.org>,
Thomas Gleixner <tglx@...utronix.de>,
Miroslav Lichvar <mlichvar@...hat.com>,
Richard Cochran <richardcochran@...il.com>,
Prarit Bhargava <prarit@...hat.com>,
Stephen Boyd <stephen.boyd@...aro.org>,
Daniel Mentz <danielmentz@...gle.com>
Subject: Re: [RFC][PATCH 0/4] Fixes for two recently found timekeeping bugs
* John Stultz <john.stultz@...aro.org> wrote:
> As part of the Linaro Linux Kernel Functional Test (LKFT)
> effort, test failures from kselftest/timer's
> inconsistency-check were reported connected to
> CLOCK_MONOTONIC_RAW, on the HiKey platform.
>
> Digging in I found that an old issue with how sub-ns accounting
> is handled with the RAW time which was fixed long ago with the
> CLOCK_MONOTONIC/REALTIME ids, but missed with RAW time, was
> present.
>
> Additionally, running further tests, I uncovered an issue with
> how the clocksource read function is handled when clocksources
> are changed, which can cause crashes.
>
> Both of these issues have not been uncovered in x86 based
> testing due to x86 not using vDSO to accelerate
> CLOCK_MONOTONIC_RAW, combined with the HiKey's arch_timer
> clocksource being fast to access but incrementing slowly enough
> to get multiple reads using the same counter value (which helps
> uncover time handing issues), along with the fact that none of
> the x86 clocksources making use of the clocksource argument
> passed to the read function.
>
> This patchset addresses these two issues.
AFAICS only the first two patches are fixes, the other two patches are
cleanups/simplifications that resulted out of the debugging effort, right?
Thanks,
Ingo
Powered by blists - more mailing lists