linux-kernel - Re: [PATCH v2 02/10] x86/percpu: Clean up percpu_to

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Message-ID: <CAKwvOdkccfLX59iCH0tFrwbG2Qd0XeOtKuupih+iosE5xwP0BQ@mail.gmail.com>
Date:   Fri, 10 Jul 2020 09:56:16 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Peter Zijlstra <peterz@...radead.org>
Cc:     Brian Gerst <brgerst@...il.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        "the arch/x86 maintainers" <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Andy Lutomirski <luto@...nel.org>
Subject: Re: [PATCH v2 02/10] x86/percpu: Clean up percpu_to_op()

On Fri, Jul 10, 2020 at 1:53 AM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Fri, Jul 10, 2020 at 12:38:23AM -0400, Brian Gerst wrote:
> > On Thu, Jul 9, 2020 at 6:30 AM Peter Zijlstra <peterz@...radead.org> wrote:
> > >
> > > On Sat, May 30, 2020 at 06:11:19PM -0400, Brian Gerst wrote:
> > > > +     if (0) {                                                        \
> > > > +             typeof(_var) pto_tmp__;                                 \
> > > > +             pto_tmp__ = (_val);                                     \
> > > > +             (void)pto_tmp__;                                        \
> > > > +     }                                                               \
> > >
> > > This is repeated at least once more; and it looks very similar to
> > > __typecheck() and typecheck() but is yet another variant afaict.
> >
> > The problem with typecheck() is that it will complain about a mismatch
> > between unsigned long and u64 (defined as unsigned long long) even
> > though both are 64-bits wide on x86-64.  Cleaning that mess up is
> > beyond the scope of this series, so I kept the existing checks.
>
> Fair enough; thanks for explaining.

I brought up the same point in v1, for more context:
https://lore.kernel.org/lkml/CAKwvOdnCcpS_9A2y9tMqeiAg2NfcVx=gNeA2V=+zHknit7wGkg@mail.gmail.com/
-- 
Thanks,
~Nick Desaulniers