linux-kernel - Re: [PATCH 5/8] x86: switch atomic.h to use atomic-instrumented.h

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Message-ID: <20170329133736.GJ23442@leverpostej>
Date:   Wed, 29 Mar 2017 14:37:36 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Dmitry Vyukov <dvyukov@...gle.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Will Deacon <will.deacon@....com>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        kasan-dev <kasan-dev@...glegroups.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>
Subject: Re: [PATCH 5/8] x86: switch atomic.h to use atomic-instrumented.h

On Tue, Mar 28, 2017 at 06:25:07PM +0200, Dmitry Vyukov wrote:
> On Tue, Mar 28, 2017 at 6:15 PM, Dmitry Vyukov <dvyukov@...gle.com> wrote:

> >  #define __try_cmpxchg(ptr, pold, new, size)                            \
> >         __raw_try_cmpxchg((ptr), (pold), (new), (size), LOCK_PREFIX)
> >
> > -#define try_cmpxchg(ptr, pold, new)                                    \
> > +#define arch_try_cmpxchg(ptr, pold, new)                               \
> >         __try_cmpxchg((ptr), (pold), (new), sizeof(*(ptr)))
> 
> Is try_cmpxchg() a part of public interface like cmpxchg, or only a
> helper to implement atomic_try_cmpxchg()?
> If it's the latter than we don't need to wrap them.

De-facto, it's an x86-specific helper. It was added in commit:

    a9ebf306f52c756c ("locking/atomic: Introduce atomic_try_cmpxchg()")

... which did not add try_cmpxchg to any generic header.

If it was meant to be part of the public interface, we'd need a generic
definition.

Thanks,
Mark.