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Date: Wed, 15 Jul 2026 09:03:10 -0700
From: Kees Cook <kees@kernel.org>
To: David Matlack <dmatlack@google.com>
Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org,
	llvm@lists.linux.dev, Andy Lutomirski <luto@amacapital.net>,
	Bill Wendling <morbo@google.com>,
	Justin Stitt <justinstitt@google.com>,
	=?iso-8859-1?Q?Micka=EBl_Sala=FCn?= <mic@digikod.net>,
	Nathan Chancellor <nathan@kernel.org>,
	Nick Desaulniers <nick.desaulniers+lkml@gmail.com>,
	Shuah Khan <shuah@kernel.org>, Will Drewry <wad@chromium.org>,
	Kuniyuki Iwashima <kuniyu@google.com>,
	Aaron Lewis <aaronlewis@google.com>,
	Alex Williamson <alex@shazbot.org>
Subject: Re: [PATCH v3] selftests: harness: Mark test fixture objects
 __maybe_unused
Message-ID: <202607150902.F17F8DE5@keescook>
References: <20260706183154.2660394-1-dmatlack@google.com>
 <CALzav=f3KaNQd2NgCTxU=VSXWujV+qjyQuNJp_hy1-U36RMPpg@mail.gmail.com>
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In-Reply-To: <CALzav=f3KaNQd2NgCTxU=VSXWujV+qjyQuNJp_hy1-U36RMPpg@mail.gmail.com>

On Tue, Jul 14, 2026 at 09:24:36AM -0700, David Matlack wrote:
> On Mon, Jul 6, 2026 at 11:32 AM David Matlack <dmatlack@google.com> wrote:
> >
> > Mark _##fixture_name##_##test_name##_object __maybe_unused since it may
> > not ever be read. This pointer is only read in XFAIL_ADD(), which tests
> > are not required to use.
> >
> > clang made a change to -Wunused-but-set-variable (split out into its own
> > subwarning, -Wunused-but-set-global) that causes this warning to be
> > emitted for various selftests and can be upgraded to an error in
> > selftest that set -Werror.
> >
> > VFIO selftests have been broken since commit ff556bd98348 ("vfio:
> > selftests: Add -Wall and -Werror to the Makefile"), and the net
> > selftests builds have been noisy due to -Wall.
> >
> > Fixes: 24cf65a62266 ("selftests/harness: Share _metadata between forked processes")
> > Reported-by: Kuniyuki Iwashima <kuniyu@google.com>
> > Reported-by: Aaron Lewis <aaronlewis@google.com>
> > Reviewed-by: Alex Williamson <alex@shazbot.org>
> > Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
> > Signed-off-by: David Matlack <dmatlack@google.com>
> 
> Kees and Shuah, is it ok if Alex takes this through the VFIO tree? [1]
> This fixes a bug exposed by recent VFIO selftests commit ff556bd98348
> ("vfio: selftests: Add -Wall and -Werror to the Makefile").
> 
> [1] https://lore.kernel.org/linux-kselftest/20260630165244.0d013bbc@shazbot.org/

Yeah, please do. This has ample review. :)

-- 
Kees Cook