linux-kernel - Re: [PATCH 2/2] selftests/harness: Merge TEST_F_FORK() into TEST

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Date: Mon, 26 Feb 2024 21:21:06 +0100
From: Mickaël Salaün <mic@...ikod.net>
To: Kees Cook <keescook@...omium.org>
Cc: Jakub Kicinski <kuba@...nel.org>, Shuah Khan <shuah@...nel.org>, 
	davem@...emloft.net, Günther Noack <gnoack@...gle.com>, 
	Will Drewry <wad@...omium.org>, edumazet@...gle.com, jakub@...udflare.com, pabeni@...hat.com, 
	linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org, 
	linux-security-module@...r.kernel.org, netdev@...r.kernel.org
Subject: Re: [PATCH 2/2] selftests/harness: Merge TEST_F_FORK() into TEST_F()

On Mon, Feb 26, 2024 at 11:04:12AM -0800, Kees Cook wrote:
> On Mon, Feb 26, 2024 at 05:23:35PM +0100, Mickaël Salaün wrote:
> > Remplace Landlock-specific TEST_F_FORK() with an improved TEST_F() which
> > brings four related changes:
> > 
> > Run TEST_F()'s tests in a grandchild process to make it possible to
> > drop privileges and delegate teardown to the parent.
> > 
> > Compared to TEST_F_FORK(), simplify handling of the test grandchild
> > process thanks to vfork(2), and makes it generic (e.g. no explicit
> > conversion between exit code and _metadata).
> > 
> > Compared to TEST_F_FORK(), run teardown even when tests failed with an
> > assert thanks to commit 63e6b2a42342 ("selftests/harness: Run TEARDOWN
> > for ASSERT failures").
> > 
> > Simplify the test harness code by removing the no_print and step fields
> > which are not used.  I added this feature just after I made
> > kselftest_harness.h more broadly available but this step counter
> > remained even though it wasn't needed after all. See commit 369130b63178
> > ("selftests: Enhance kselftest_harness.h to print which assert failed").
> 
> I'm personally fine dropping the step counter. (I do wonder if that
> removal should be split from the grandchild launching.)

I thought about that but it was not worth it to add more lines to
review.

> 
> > Replace spaces with tabs in one line of __TEST_F_IMPL().
> > 
> > Cc: Günther Noack <gnoack@...gle.com>
> > Cc: Jakub Kicinski <kuba@...nel.org>
> > Cc: Kees Cook <keescook@...omium.org>
> > Cc: Shuah Khan <shuah@...nel.org>
> > Cc: Will Drewry <wad@...omium.org>
> > Signed-off-by: Mickaël Salaün <mic@...ikod.net>
> 
> One typo below, but otherwise seems good to me:
> 
> Reviewed-by: Kees Cook <keescook@...omium.org>
> 
> 
> > [...]
> >  			_metadata->setup_completed = true; \
> > -			fixture_name##_##test_name(_metadata, &self, variant->data); \
> > +			/* Use the same _metadata. */ \
> > +			child = vfork(); \
> > +			if (child == 0) { \
> > +				fixture_name##_##test_name(_metadata, &self, variant->data); \
> > +				_exit(0); \
> > +			} \
> > +			if (child < 0) { \
> > +				ksft_print_msg("ERROR SPAWNING TEST GANDCHILD\n"); \
> 
> typo: GAND -> GRAND

Good catch!

Jakub, please fix this with the next combined+rebased series. Thanks!

> 
> -- 
> Kees Cook
>