linux-kernel - Re: [PATCH v2 2/2] x86: paravirt: make native_save

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Date:   Tue, 5 Jun 2018 14:51:23 -0700
From:   Nick Desaulniers <ndesaulniers@...gle.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>, akataria@...are.com,
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        Cao jin <caoj.fnst@...fujitsu.com>,
        Greg KH <gregkh@...uxfoundation.org>, hpa@...or.com,
        "J. Kiszka" <jan.kiszka@...mens.com>,
        jarkko.sakkinen@...ux.intel.com, jgross@...e.com,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        kirill.shutemov@...ux.intel.com, mingo@...hat.com,
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        Philippe Ombredanne <pombredanne@...b.com>,
        rostedt@...dmis.org, Thomas Gleixner <tglx@...utronix.de>,
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        geert@...ux-m68k.org, Will Deacon <will.deacon@....com>,
        mawilcox@...rosoft.com, David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH v2 2/2] x86: paravirt: make native_save_fl extern inline

On Tue, Jun 5, 2018 at 2:31 PM Arnd Bergmann <arnd@...db.de> wrote:
>
> On Tue, Jun 5, 2018 at 11:28 PM, Arnd Bergmann <arnd@...db.de> wrote:
> > On Tue, Jun 5, 2018 at 7:05 PM, Nick Desaulniers
> > <ndesaulniers@...gle.com> wrote:
> >>
> >> The semantics of extern inline has changed since gnu89. This means that
> >> folks using GCC versions >= 5.1 may see symbol redefinition errors at
> >> link time for subdirs that override KBUILD_CFLAGS (making the C standard
> >> used implicit) regardless of this patch. This has been cleaned up
> >> earlier in the patch set, but is left as a note in the commit message
> >> for future travelers.
> >
> > I think the keyword you are missing is
> >
> > __attribute__((gnu_inline))
> >
> > which forces the gnu89 behavior on all compiler versions. It's been supported
> > since gcc-4.2, so it should not cause problems on any compiler that is able
> > to build an x86 kernel.
>
> Nevermind, I just saw you already posted that.
>
>        Arnd

That's ok, I appreciate you taking the time to review.  Your point
made me consider adding the function attribute to just
native_save_fl() in this patch, but it seems that that lone function
attribute is not used outside of compiler-gcc.h, so it would be good
to change all users of inline in one place.
-- 
Thanks,
~Nick Desaulniers