Messages in this thread | | | Date | Sat, 27 May 2017 09:38:36 +0200 | From | Ingo Molnar <> | Subject | 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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