linux-kernel - Re: [RFC PATCH] compiler_attributes.h: Add 'fallthrough' pseudo keyword for switch/case use

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Message-ID: <e31f3918342683a4f56302be301208137e60566f.camel@perches.com>
Date:   Thu, 01 Aug 2019 13:47:47 -0700
From:   Joe Perches <joe@...ches.com>
To:     Miguel Ojeda <miguel.ojeda.sandonis@...il.com>,
        "H. Peter Anvin" <hpa@...or.com>
Cc:     Peter Zijlstra <peterz@...radead.org>, Pavel Machek <pavel@....cz>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Borislav Petkov <bp@...en8.de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "Gustavo A . R . Silva" <gustavo@...eddedor.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Kan Liang <kan.liang@...ux.intel.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Shawn Landden <shawn@....icu>,
        "maintainer:X86 ARCHITECTURE (32-BIT AND 64-BIT)" <x86@...nel.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [RFC PATCH] compiler_attributes.h: Add 'fallthrough' pseudo
 keyword for switch/case use

On Thu, 2019-08-01 at 22:26 +0200, Miguel Ojeda wrote:
> On Thu, Aug 1, 2019 at 10:10 PM <hpa@...or.com> wrote:
> > I'm not disagreeing... I think using a macro makes sense.
> 
> It is either a macro or waiting for 5+ years (while we keep using the
> comment style) :-)
> 
> In case it helps to make one's mind about whether to go for it or not,
> I summarized the advantages and a few other details in the patch I
> sent in October:
> 
>   https://github.com/ojeda/linux/commit/668f011a2706ea555987e263f609a5deba9c7fc4
> 
> It would be nice, however, to discuss whether we want __fallthrough or
> fallthrough.

I was happy enough with either though after a bit of
playing around with both, I think the pseudo-keyword
reads quite a bit better.

linux-kernel is a constrained code base and using
underscored prefixes is not really necessary.

For instance:

_Bool is c99, but the kernel uses bool
uint8_t also, but the kernel uses u8, etc...

Yes it requires a bit of 'local knowledge',
but simpler is better.