Subject: Re: [PATCH v4 00/12] selftests: kselftest_harness: support using xfail

From: Kees Cook <[email-masked]>
Date: Mon, 4 Mar 2024 15:14:04 -0800

On Mon, Mar 04, 2024 at 03:04:11PM -0800, Jakub Kicinski wrote:
> On Mon, 4 Mar 2024 22:20:03 +0000 Mark Brown wrote:
> > On Wed, Feb 28, 2024 at 04:59:07PM -0800, Jakub Kicinski wrote:
> > 
> > > When running selftests for our subsystem in our CI we'd like all
> > > tests to pass. Currently some tests use SKIP for cases they
> > > expect to fail, because the kselftest_harness limits the return
> > > codes to pass/fail/skip. XFAIL which would be a great match
> > > here cannot be used.
> > > 
> > > Remove the no_print handling and use vfork() to run the test in
> > > a different process than the setup. This way we don't need to
> > > pass "failing step" via the exit code. Further clean up the exit
> > > codes so that we can use all KSFT_* values. Rewrite the result
> > > printing to make handling XFAIL/XPASS easier. Support tests
> > > declaring combinations of fixture + variant they expect to fail.  
> > 
> > This series landed in -next today and has caused breakage on all
> > platforms in the ALSA pcmtest-driver test.  When run on systems that
> > don't have the driver it needs loaded the test skip but since this
> > series was merged skipped tests are logged but then reported back as
> > failures:
> > 
> > # selftests: alsa: test-pcmtest-driver
> > # TAP version 13
> > # 1..5
> > # # Starting 5 tests from 1 test cases.
> > # #  RUN           pcmtest.playback ...
> > # #      SKIP      Can't read patterns. Probably, module isn't loaded
> > # # playback: Test failed
> > # #          FAIL  pcmtest.playback
> > # not ok 1 pcmtest.playback #  Can't read patterns. Probably, module isn't loaded
> > # #  RUN           pcmtest.capture ...
> > # #      SKIP      Can't read patterns. Probably, module isn't loaded
> > # # capture: Test failed
> > # #          FAIL  pcmtest.capture
> > # not ok 2 pcmtest.capture #  Can't read patterns. Probably, module isn't loaded
> > # #  RUN           pcmtest.ni_capture ...
> > # #      SKIP      Can't read patterns. Probably, module isn't loaded
> > # # ni_capture: Test failed
> > # #          FAIL  pcmtest.ni_capture
> > # not ok 3 pcmtest.ni_capture #  Can't read patterns. Probably, module isn't loaded
> > # #  RUN           pcmtest.ni_playback ...
> > # #      SKIP      Can't read patterns. Probably, module isn't loaded
> > # # ni_playback: Test failed
> > # #          FAIL  pcmtest.ni_playback
> > # not ok 4 pcmtest.ni_playback #  Can't read patterns. Probably, module isn't loaded
> > # #  RUN           pcmtest.reset_ioctl ...
> > # #      SKIP      Can't read patterns. Probably, module isn't loaded
> > # # reset_ioctl: Test failed
> > # #          FAIL  pcmtest.reset_ioctl
> > # not ok 5 pcmtest.reset_ioctl #  Can't read patterns. Probably, module isn't loaded
> > # # FAILED: 0 / 5 tests passed.
> > # # Totals: pass:0 fail:5 xfail:0 xpass:0 skip:0 error:0
> > 
> > I haven't completely isolated the issue due to some other breakage
> > that's making it harder that it should be to test.  
> > 
> > A sample full log can be seen at:
> > 
> >    https://lava.sirena.org.uk/scheduler/job/659576#L1349
> 
> Thanks! the exit() inside the skip evaded my grep, I'm testing this:
> 
> diff --git a/tools/testing/selftests/alsa/test-pcmtest-driver.c b/tools/testing/selftests/alsa/test-pcmtest-driver.c
> index a52ecd43dbe3..7ab81d6f9e05 100644
> --- a/tools/testing/selftests/alsa/test-pcmtest-driver.c
> +++ b/tools/testing/selftests/alsa/test-pcmtest-driver.c
> @@ -127,11 +127,11 @@ FIXTURE_SETUP(pcmtest) {
>  	int err;
>  
>  	if (geteuid())
> -		SKIP(exit(-1), "This test needs root to run!");
> +		SKIP(exit(KSFT_SKIP), "This test needs root to run!");
>  
>  	err = read_patterns();
>  	if (err)
> -		SKIP(exit(-1), "Can't read patterns. Probably, module isn't loaded");
> +		SKIP(exit(KSFT_SKIP), "Can't read patterns. Probably, module isn't loaded");
>  
>  	card_name = malloc(127);
>  	ASSERT_NE(card_name, NULL);
> diff --git a/tools/testing/selftests/mm/hmm-tests.c b/tools/testing/selftests/mm/hmm-tests.c
> index 20294553a5dd..356ba5f3b68c 100644
> --- a/tools/testing/selftests/mm/hmm-tests.c
> +++ b/tools/testing/selftests/mm/hmm-tests.c
> @@ -138,7 +138,7 @@ FIXTURE_SETUP(hmm)
>  
>  	self->fd = hmm_open(variant->device_number);
>  	if (self->fd < 0 && hmm_is_coherent_type(variant->device_number))
> -		SKIP(exit(0), "DEVICE_COHERENT not available");
> +		SKIP(exit(KSFT_SKIP), "DEVICE_COHERENT not available");
>  	ASSERT_GE(self->fd, 0);
>  }
>  
> @@ -149,7 +149,7 @@ FIXTURE_SETUP(hmm2)
>  
>  	self->fd0 = hmm_open(variant->device_number0);
>  	if (self->fd0 < 0 && hmm_is_coherent_type(variant->device_number0))
> -		SKIP(exit(0), "DEVICE_COHERENT not available");
> +		SKIP(exit(KSFT_SKIP), "DEVICE_COHERENT not available");
>  	ASSERT_GE(self->fd0, 0);
>  	self->fd1 = hmm_open(variant->device_number1);
>  	ASSERT_GE(self->fd1, 0);
> 
> > but there's no more context.  I'm also seeing some breakage in the
> > seccomp selftests which also use kselftest-harness:
> > 
> > # #  RUN           TRAP.dfl ...
> > # # dfl: Test exited normally instead of by signal (code: 0)
> > # #          FAIL  TRAP.dfl
> > # not ok 56 TRAP.dfl
> > # #  RUN           TRAP.ign ...
> > # # ign: Test exited normally instead of by signal (code: 0)
> > # #          FAIL  TRAP.ign
> > # not ok 57 TRAP.ign
> 
> Ugh, I'm guessing vfork() "eats" the signal, IOW grandchild signals,
> child exits? vfork() and signals.. I'd rather leave to Kees || Mickael.

Oh no, that does seem bad. Since Mickaël is also seeing weird issues,
can we drop the vfork changes for now?

-- 
Kees Cook