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From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Fri, 14 Dec 2018 09:46:39 -0800
Message-ID: <CAKwvOdmF2rx-A=chY70pvDVHEacRT5Mh9KVbL=pLy4O7jHTNMQ@mail.gmail.com>
Subject: Re: [PATCH v3] Compiler Attributes: don't pollute userspace with
 macro definitions
To:     Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Cc:     liuxiaozhou@bytedance.com,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Luc Van Oostenryck <luc.vanoostenryck@gmail.com>,
        Masahiro Yamada <yamada.masahiro@socionext.com>,
        paul.burton@mips.com, Kees Cook <keescook@chromium.org>,
        Arnd Bergmann <arnd@arndb.de>,
        LKML <linux-kernel@vger.kernel.org>
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On Fri, Dec 14, 2018 at 8:06 AM Miguel Ojeda
<miguel.ojeda.sandonis@gmail.com> wrote:
>
> On Fri, Dec 14, 2018 at 3:16 PM Xiaozhou Liu <liuxiaozhou@bytedance.com> =
wrote:
> >
> > Macros 'inline' and '__gnu_inline' used to be defined in compiler-gcc.h=
,
> > which was (and is) included entirely in (__KERNEL__ && !__ASSEMBLY__).
> > Commit 815f0ddb346c ("include/linux/compiler*.h: make compiler-*.h mutu=
ally
> > exclusive") had those macros exposed to userspace, unintentionally.
> >
> > Then commit a3f8a30f3f00 ("Compiler Attributes: use feature checks
> > instead of version checks") moved '__gnu_inline' back into
> > (__KERNEL__ && !__ASSEMBLY__) and 'inline' was left behind. Since 'inli=
ne'
> > depends on '__gnu_inline', compiling error showing "unknown type name
> > =E2=80=98__gnu_inline=E2=80=99" will pop up, if userspace somehow inclu=
des
> > <linux/compiler.h>.
> >
> > Other macros like __must_check, notrace, etc. are in a similar situatio=
n.
> > So just move all these macros back into (__KERNEL__ && !__ASSEMBLY__).
> >
> > Note:
> >   1. This patch only affects what userspace sees.
> >   2. __must_check (when !CONFIG_ENABLE_MUST_CHECK) and noinline_for_sta=
ck
> >      were once defined in __KERNEL__ only, but we believe that they can
> >      be put into !__ASSEMBLY__ too.
> >
> > Acked-by: Nick Desaulniers <ndesaulniers@google.com>
> > Signed-off-by: Xiaozhou Liu <liuxiaozhou@bytedance.com>
>
> Thanks Xiaozhou, picked into compiler-attributes with a slightly
> modified title (since it is not about compiler attributes this time),
> and let's see if there is any problem with it in linux-next.
>
> Nick: I kept your Ack, even if it is a different patch. Let me know if
> you don't want to Ack this version.

Doubled-acked-by: Nick Desaulniers <ndesaulniers@google.com>
(I recognize it's always ambiguous whether to carry forward sign-offs
when a patch set changes)
--=20
Thanks,
~Nick Desaulniers