Re: [PATCH] selftests/timers/posix_timers: reimplement check_timer_distribution()

From: Oleg Nesterov <oleg@redhat.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Mark Brown <broonie@kernel.org>, John Stultz <jstultz@google.com>,
	Marco Elver <elver@google.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Ingo Molnar <mingo@kernel.org>,
	"Eric W. Biederman" <ebiederm@xmission.com>,
	linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	Dmitry Vyukov <dvyukov@google.com>,
	kasan-dev@googlegroups.com, Edward Liaw <edliaw@google.com>,
	Carlos Llamas <cmllamas@google.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: [PATCH] selftests/timers/posix_timers: reimplement check_timer_distribution()
Date: Thu, 11 Apr 2024 17:50:53 +0200	[thread overview]
Message-ID: <20240411155053.GD5494@redhat.com> (raw)
In-Reply-To: <87il0o0yrc.ffs@tglx>

On 04/11, Thomas Gleixner wrote:
>
> On Thu, Apr 11 2024 at 13:44, Mark Brown wrote:
> >
> > Further to my previous mail it's also broken the arm64 selftest builds,
> > they use kselftest.h with nolibc in order to test low level
> > functionality mainly used by libc implementations and nolibc doesn't
> > implement uname():
> >
> > In file included from za-fork.c:12:
> > ../../kselftest.h:433:17: error: variable has incomplete type 'struct utsname'
> >         struct utsname info;
> >                        ^
> > ../../kselftest.h:433:9: note: forward declaration of 'struct utsname'
> >         struct utsname info;
> >                ^
> > ../../kselftest.h:435:6: error: call to undeclared function 'uname'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
> >         if (uname(&info) || sscanf(info.release, "%u.%u.", &major, &minor) != 2)
> >             ^
> > ../../kselftest.h:435:22: error: call to undeclared function 'sscanf'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
> >         if (uname(&info) || sscanf(info.release, "%u.%u.", &major, &minor) != 2)
>
> Grrr. Let me stare at this.

Damn ;)

Can't we just turn ksft_min_kernel_version() into

	static inline int ksft_min_kernel_version(unsigned int min_major,
						  unsigned int min_minor)
	{
	#ifdef NOLIBC
		return -1;
	#else
		unsigned int major, minor;
		struct utsname info;

		if (uname(&info) || sscanf(info.release, "%u.%u.", &major, &minor) != 2)
		       ksft_exit_fail_msg("Can't parse kernel version\n");

		return major > min_major || (major == min_major && minor >= min_minor);
	#endif
	}

?

Not sure what should check_timer_distribution() do in this case, to me
ksft_test_result_fail() is fine.

Oleg.