linux-kernel - Re: [PATCH v3 1/4] KVM: selftests: Explicitly set variables based on options in dirty_log_perf

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Date:   Wed, 21 Sep 2022 10:55:13 -0700
From:   David Matlack <dmatlack@...gle.com>
To:     Vipin Sharma <vipinsh@...gle.com>
Cc:     seanjc@...gle.com, pbonzini@...hat.com, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 1/4] KVM: selftests: Explicitly set variables based on
 options in dirty_log_perf_test

On Fri, Aug 26, 2022 at 02:12:49PM -0700, Vipin Sharma wrote:
> On Fri, Aug 26, 2022 at 11:45 AM Vipin Sharma <vipinsh@...gle.com> wrote:
> >
> > Variable set via -g are also indirectly set by -e option by omitting
> > break statement. Set them explicitly so that movement of switch-case
> > statements does not unintentionally break features.
> >
> > No functional change intended.
> >
> > Signed-off-by: Vipin Sharma <vipinsh@...gle.com>
> > ---
> >  tools/testing/selftests/kvm/dirty_log_perf_test.c | 2 ++
> >  1 file changed, 2 insertions(+)
> >
> > diff --git a/tools/testing/selftests/kvm/dirty_log_perf_test.c b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> > index f99e39a672d3..a03db7f9f4c0 100644
> > --- a/tools/testing/selftests/kvm/dirty_log_perf_test.c
> > +++ b/tools/testing/selftests/kvm/dirty_log_perf_test.c
> > @@ -411,6 +411,8 @@ int main(int argc, char *argv[])
> >                 case 'e':
> >                         /* 'e' is for evil. */
> >                         run_vcpus_while_disabling_dirty_logging = true;
> > +                       dirty_log_manual_caps = 0;
> > +                       break;
> 
> @Sean, I hope you intentionally didn't write a break between -e and -g
> when you created the patch and it is not just a missed thing :)

I'm pretty sure the missing break here is by accident. If it was on
purpose I would expect Sean (especially) to have called it out the
subtle change in the commit message and probably add a comment here.
Also I can't think of any reason why
run_vcpus_while_disabling_dirty_logging=true would require
dirty_log_manual_caps=0.

Can you change this patch to just add a break and add a fixes tag to the
commit message?

Fixes: cfe12e64b065 ("KVM: selftests: Add an option to run vCPUs while disabling dirty logging")


> 
> 
> >                 case 'g':
> >                         dirty_log_manual_caps = 0;
> >                         break;
> > --
> > 2.37.2.672.g94769d06f0-goog
> >