Re: [PATCH v2 3/6] compiler_types.h: don't #define __inline

From: Nick Desaulniers <ndesaulniers@google.com>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)"
	<x86@kernel.org>, LKML <linux-kernel@vger.kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	"H. Peter Anvin" <hpa@zytor.com>, Nadav Amit <namit@vmware.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Miguel Ojeda <miguel.ojeda.sandonis@gmail.com>
Subject: Re: [PATCH v2 3/6] compiler_types.h: don't #define __inline
Date: Wed, 4 Sep 2019 17:13:53 -0700	[thread overview]
Message-ID: <CAKwvOdn2zbRCL+L92zjjuyhj4NLLtOEWd3pjady9KyYb7PAbmw@mail.gmail.com> (raw)
In-Reply-To: <20190830231527.22304-4-linux@rasmusvillemoes.dk>

On Fri, Aug 30, 2019 at 4:15 PM Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
>
> The spellings __inline and __inline__ should be reserved for uses
> where one really wants to refer to the inline keyword, regardless of
> whether or not the spelling "inline" has been #defined to something
> else. Due to use of __inline__ in uapi headers, we can't easily get
> rid of the definition of __inline__. However, almost all users of
> __inline has been converted to inline, so we can get rid of that
> #define.

Besides patch 1 and 2 of this series, I also see:
Documentation/trace/tracepoint-analysis.rst
318:         :      extern __inline void
__attribute__((__gnu_inline__, __always_inline__, _

scripts/kernel-doc
1574:    $prototype =~ s/^__inline +//;

>
> The exception is include/acpi/platform/acintel.h. However, that header
> is only included when using the intel compiler (does anybody actually
> build the kernel with that?), and the ACPI_INLINE macro is only used

In my effort to make the kernel slightly more compiler-portable, I
have not yet found anyone building with ICC.  I would love to be
proven wrong.  Let me go ask some of my Intel friends.

> in the definition of utterly trivial stub functions, where I doubt a

See:
include/acpi/platform/acenv.h
146 #elif defined(__INTEL_COMPILER)
147 #include <acpi/platform/acintel.h>

> small change of semantics (lack of __gnu_inline) changes anything.

include/acpi/platform/acintel.h
25:#define ACPI_INLINE                 __inline
include/acpi/platform/acgcc.h
29:#define ACPI_INLINE             __inline__

lol wut

I mean, you just would have to change that one line in
include/acpi/platform/acintel.h, right?  I'd sign off on this patch
with such a patch added to the series.

>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
>  include/linux/compiler_types.h | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/compiler_types.h b/include/linux/compiler_types.h
> index 599c27b56c29..ee49be6d6088 100644
> --- a/include/linux/compiler_types.h
> +++ b/include/linux/compiler_types.h
> @@ -150,8 +150,17 @@ struct ftrace_likely_data {
>         __maybe_unused notrace
>  #endif
>
> +/*
> + * gcc provides both __inline__ and __inline as alternate spellings of
> + * the inline keyword, though the latter is undocumented. New kernel
> + * code should only use the inline spelling, but some existing code
> + * uses __inline__. Since we #define inline above, to ensure
> + * __inline__ has the same semantics, we need this #define.
> + *
> + * However, the spelling __inline is strictly reserved for referring
> + * to the bare keyword.
> + */
>  #define __inline__ inline
> -#define __inline   inline
>
>  /*
>   * Rather then using noinline to prevent stack consumption, use
> --
> 2.20.1
>

-- 
Thanks,
~Nick Desaulniers