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

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Date:   Fri, 10 Jul 2020 10:53:27 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Brian Gerst <brgerst@...il.com>
Cc:     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>,
        Nick Desaulniers <ndesaulniers@...gle.com>
Subject: Re: [PATCH v2 02/10] x86/percpu: Clean up percpu_to_op()

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.