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SubjectRe: [tip:timers/core] kselftests: timers: set-timer-lat: Tweak reporting when timer fires early
On 09/20/2017 06:31 AM, Prarit Bhargava wrote:
> On 09/19/2017 11:36 PM, John Stultz wrote:
>> On Tue, Sep 19, 2017 at 6:02 PM, Shuah Khan <> wrote:
>>> Hi Greg,
>>> On 08/20/2017 03:56 AM, tip-bot for Greg Hackmann wrote:
>>>> Commit-ID: a524b1184b8e86141d689fa78ad150fbf2db9b4c
>>>> Gitweb:
>>>> Author: Greg Hackmann <>
>>>> AuthorDate: Tue, 25 Jul 2017 14:36:25 -0700
>>>> Committer: John Stultz <>
>>>> CommitDate: Thu, 17 Aug 2017 12:14:54 -0700
>>>> kselftests: timers: set-timer-lat: Tweak reporting when timer fires early
>>>> Rather than printing an error inside the alarm signal handler, set a
>>>> flag that we check later. This keeps the test from spamming the console
>>>> every time the alarm fires early. It also fixes the test exiting with
>>>> error code 0 if this was the only test failure.
>>>> Cc: Thomas Gleixner <>
>>>> Cc: Ingo Molnar <>
>>>> Cc: Miroslav Lichvar <>
>>>> Cc: Richard Cochran <>
>>>> Cc: Prarit Bhargava <>
>>>> Cc: Stephen Boyd <>
>>>> Cc: Shuah Khan <>
>>>> Cc:
>>>> Signed-off-by: Greg Hackmann <>
>>>> Signed-off-by: John Stultz <>
>>> This commit is making the set-timer-lat hang. I reverted this commit
>>> and there is no hang. Could you please take a look and see if this
>>> commit should be reverted.
>>> make kselftest as well as make -C tools/testing/selftests/timers run_tests
>>> hang.
>> Do you have any specific details as to how the test hangs? (ie: Log
>> data, as in where it might be when it hangs? Any details about the
>> machine?)
>> I'm not seeing it so far in my testing.
> I just ran it here and don't see any issues. I'll try on a few other boxes
> to make sure.
> # make -C tools/testing/selftests/timers run_tests


Thanks for getting back to me. I isolated the problem to redirecting
test output. If I redirect the output it hangs.

./set-timer-lat > /tmp/set-timer-lat 2>&1

it hangs. The reason I am seeing this is because there is a patch
that came in recently to redirect individual test output to a separate
file to make it easier to understand the test results.

Looks like Commits 28be3f8f48cfb3cf024860f042d424cd4824f5f7 and/or
a524b1184b8e86141d689fa78ad150fbf2db9b4c add dependency on stdin/out/err
to the test.

Anyway just an update. It can be reproduced easily. If we have tests
that can't tolerate redirecting output, I might end up dropping the
patch that is in linux-kselftest fixes


So fat set-timer-lat is the only one I found.

-- Shuah

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