linux-kernel - Re: [PATCH] selftests/kvm: add get_msr_index

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Message-ID: <20210318175542.xv7qaehgx2cjmuvv@kamzik.brq.redhat.com>
Date:   Thu, 18 Mar 2021 18:55:42 +0100
From:   Andrew Jones <drjones@...hat.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Emanuele Giuseppe Esposito <eesposit@...hat.com>,
        linux-kselftest@...r.kernel.org, Shuah Khan <shuah@...nel.org>,
        Vitaly Kuznetsov <vkuznets@...hat.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] selftests/kvm: add get_msr_index_features

On Thu, Mar 18, 2021 at 06:33:35PM +0100, Paolo Bonzini wrote:
> On 18/03/21 18:03, Andrew Jones wrote:
> > > 
> > >  TEST_GEN_PROGS_x86_64 = x86_64/cr4_cpuid_sync_test
> > > +TEST_GEN_PROGS_x86_64 += x86_64/get_msr_index_features
> > 
> > Maybe we should give up trying to keep an alphabetic order.
> 
> FWIW I had fixed that but yeah maybe we should just give up.
> 
> > > +int main(int argc, char *argv[])
> > > +{
> > > +	if (kvm_check_cap(KVM_CAP_GET_MSR_FEATURES))
> > > +		test_get_msr_feature();
> > > +
> > > +	test_get_msr_index();
> > Missing return
> > 
> > > +}
> 
> "main" is special, it's okay not to have a return there.

Hmm, yeah. I always assumed the compiler would complain or that you'd end
up with a garbage return code. But, I just checked, and indeed not only do
you not get a warning, even with -Wall -Wextra, but the compiler actually
emits code for a zero return value on your behalf. Looks weird to me
though to end an int function without a return, so I don't think I'm
going to adopt this practice myself.

Thanks,
drew