linux-kernel - Re: [PATCH v2 1/2] selftests: Provide local define of min() and max()

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Message-ID: <ZOy3cXUJld0FskSk@google.com>
Date:   Mon, 28 Aug 2023 08:04:17 -0700
From:   Sean Christopherson <seanjc@...gle.com>
To:     keescook@...omium.org, edumazet@...gle.com,
        willemdebruijn.kernel@...il.com, wad@...omium.org,
        luto@...capital.net, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, kuba@...nel.org, shuah@...nel.org,
        pabeni@...hat.com, linux-kselftest@...r.kernel.org,
        davem@...emloft.net,
        linux-kernel-mentees@...ts.linuxfoundation.org,
        David Laight <David.Laight@...lab.com>
Subject: Re: [PATCH v2 1/2] selftests: Provide local define of min() and max()

On Sat, Aug 26, 2023, Mahmoud Matook wrote:
> On 08/25, Sean Christopherson wrote:
> 
> > On Fri, Aug 25, 2023, Mahmoud Maatuq wrote:
> > > to avoid manual calculation of min and max values
> > > and fix coccinelle warnings such WARNING opportunity for min()/max()
> > > adding one common definition that could be used in multiple files
> > > under selftests.
> > > there are also some defines for min/max scattered locally inside sources
> > > under selftests.
> > > this also prepares for cleaning up those redundant defines and include
> > > kselftest.h instead.
> > > 
> > > Signed-off-by: Mahmoud Maatuq <mahmoudmatook.mm@...il.com>
> > > Suggested-by: David Laight <David.Laight@...lab.com>
> > > ---
> > > changes in v2:
> > > redefine min/max in a more strict way to avoid 
> > > signedness mismatch and multiple evaluation.
> > > is_signed_type() moved from selftests/kselftest_harness.h 
> > > to selftests/kselftest.h.
> > > ---
> > >  tools/testing/selftests/kselftest.h         | 24 +++++++++++++++++++++
> > 
> > Heh, reminds me of https://xkcd.com/927.
> > 
> > All of these #defines are available in tools/include/linux/kernel.h, and it's
> > trivially easy for selftests to add all of tools/include to their include path.
> > I don't see any reason for the selftests framework to define yet another version,
> > just fix the individual tests.
> 
> giving the reviews seems that patchset is useless.
> still a confusing point for me; after adding tools/include to the
> include path of selftes how we can differentaite between  #include
> <linux/kernel.h> that under tools/include and one under usr/include.

AFAIK, it's up to the individual selftest (or it's "local" framework) to declare
the tools/include path before usr/include, e.g. see tools/testing/selftests/kvm/Makefile.

The whole setup is definitely a bit kludgy, but IMO it's better than conditionally
providing selftests specific fallbacks and potentially ending up with multiple
definitions of min/max within a single test.