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Re: [RFC][PATCH 0/4] Fixes for two recently found timekeeping bugs

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* John Stultz <john.stultz@linaro.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

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[RFC][PATCH 0/4] Fixes for two recently found timekeeping bugs John Stultz <john.stultz@linaro.org> - 2017-05-27 05:40 +0200
  [RFC][PATCH 4/4] time: Clean up CLOCK_MONOTONIC_RAW time handling John Stultz <john.stultz@linaro.org> - 2017-05-27 05:40 +0200
  [RFC][PATCH 2/4] time: Fix CLOCK_MONOTONIC_RAW sub-nanosecond accounting John Stultz <john.stultz@linaro.org> - 2017-05-27 05:40 +0200
    Re: [RFC][PATCH 2/4] time: Fix CLOCK_MONOTONIC_RAW sub-nanosecond  accounting Ingo Molnar <mingo@kernel.org> - 2017-05-27 09:40 +0200
      Re: [RFC][PATCH 2/4] time: Fix CLOCK_MONOTONIC_RAW sub-nanosecond accounting Daniel Mentz <danielmentz@google.com> - 2017-05-30 20:50 +0200
  [RFC][PATCH 1/4] time: Fix clock->read(clock) race around clocksource changes John Stultz <john.stultz@linaro.org> - 2017-05-27 05:40 +0200
    Re: [RFC][PATCH 1/4] time: Fix clock->read(clock) race around  clocksource changes Ingo Molnar <mingo@kernel.org> - 2017-05-27 09:40 +0200
  [RFC][PATCH 3/4] arm64: vdso: Fix nsec handling for CLOCK_MONOTONIC_RAW John Stultz <john.stultz@linaro.org> - 2017-05-27 06:20 +0200
    Re: [RFC][PATCH 3/4] arm64: vdso: Fix nsec handling for  CLOCK_MONOTONIC_RAW Will Deacon <will.deacon@arm.com> - 2017-05-30 11:40 +0200
  Re: [RFC][PATCH 0/4] Fixes for two recently found timekeeping bugs Ingo Molnar <mingo@kernel.org> - 2017-05-27 09:40 +0200
    Re: [RFC][PATCH 0/4] Fixes for two recently found timekeeping bugs John Stultz <john.stultz@linaro.org> - 2017-05-27 18:20 +0200
      Re: [RFC][PATCH 0/4] Fixes for two recently found timekeeping bugs Ingo Molnar <mingo@kernel.org> - 2017-05-28 11:00 +0200
  Re: [RFC][PATCH 0/4] Fixes for two recently found timekeeping bugs Daniel Mentz <danielmentz@google.com> - 2017-05-31 02:20 +0200

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