linux-kernel - Re: [PATCH] selftests/timers/posix_timers: reimplement check_timer

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Message-ID: <CANDhNCp=7mTSSO4cXQjYbtLrK8XRCbCyse8Bq5Wbt5V4G-K_dQ@mail.gmail.com>
Date: Thu, 11 Apr 2024 08:33:20 -0700
From: John Stultz <jstultz@...gle.com>
To: Mark Brown <broonie@...nel.org>
Cc: Oleg Nesterov <oleg@...hat.com>, Thomas Gleixner <tglx@...utronix.de>, Marco Elver <elver@...gle.com>, 
	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...nel.org>, 
	"Eric W. Biederman" <ebiederm@...ssion.com>, linux-kernel@...r.kernel.org, 
	linux-kselftest@...r.kernel.org, Dmitry Vyukov <dvyukov@...gle.com>, 
	kasan-dev@...glegroups.com, Edward Liaw <edliaw@...gle.com>, 
	Carlos Llamas <cmllamas@...gle.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: Re: [PATCH] selftests/timers/posix_timers: reimplement check_timer_distribution()

On Thu, Apr 11, 2024 at 5:42 AM Mark Brown <broonie@...nel.org> wrote:
> On Sat, Apr 06, 2024 at 05:09:51PM +0200, Oleg Nesterov wrote:
> > Without the commit bcb7ee79029d ("posix-timers: Prefer delivery of signals
> > to the current thread") the test-case fails immediately, the very 1st tick
> > wakes the leader up. Otherwise it quickly succeeds after 100 ticks.
>
> This has landed in -next and is causing warning spam throughout
> kselftest when built with clang:
>
> /home/broonie/git/bisect/tools/testing/selftests/kselftest.h:435:6: warning: variable 'major' is used uninitialized whenever '||' condition is true [-Wsometimes-uninitialized]
>         if (uname(&info) || sscanf(info.release, "%u.%u.", &major, &minor) != 2)
>             ^~~~~~~~~~~~
> /home/broonie/git/bisect/tools/testing/selftests/kselftest.h:438:9: note: uninitialized use occurs here
>         return major > min_major || (major == min_major && minor >= min_minor);
>                ^~~~~
> /home/broonie/git/bisect/tools/testing/selftests/kselftest.h:435:6: note: remove the '||' if its condition is always false
>         if (uname(&info) || sscanf(info.release, "%u.%u.", &major, &minor) != 2)
>             ^~~~~~~~~~~~~~~
> /home/broonie/git/bisect/tools/testing/selftests/kselftest.h:432:20: note: initialize the variable 'major' to silence this warning
>         unsigned int major, minor;
>                           ^
>                            = 0

I hit this one too yesterday and included a fix for it here:
  https://lore.kernel.org/lkml/20240410232637.4135564-2-jstultz@google.com/

thanks
-john