From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
        id S1752899AbdBJOms (ORCPT <rfc822;w@1wt.eu>);
        Fri, 10 Feb 2017 09:42:48 -0500
Received: from mail.kernel.org ([198.145.29.136]:53428 "EHLO mail.kernel.org"
        rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP
        id S1751577AbdBJOmr (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
        Fri, 10 Feb 2017 09:42:47 -0500
Date: Fri, 10 Feb 2017 11:42:38 -0300
From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Joe Perches <joe@perches.com>
Cc: Ingo Molnar <mingo@kernel.org>, linux-kernel@vger.kernel.org,
        Arnaldo Carvalho de Melo <acme@redhat.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        David Ahern <dsahern@gmail.com>, Jiri Olsa <jolsa@kernel.org>,
        Namhyung Kim <namhyung@kernel.org>, Wang Nan <wangnan0@huawei.com>,
        William Cohen <wcohen@redhat.com>
Subject: Re: [PATCH 24/32] tools include: Add a __fallthrough statement
Message-ID: <20170210144238.GC15066@kernel.org>
References: <20170210013940.9998-1-acme@kernel.org>
 <20170210013940.9998-25-acme@kernel.org>
 <1486695726.2192.1.camel@perches.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <1486695726.2192.1.camel@perches.com>
X-Url: http://acmel.wordpress.com
User-Agent: Mutt/1.7.1 (2016-10-04)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

Em Thu, Feb 09, 2017 at 07:02:06PM -0800, Joe Perches escreveu:
> On Thu, 2017-02-09 at 22:39 -0300, Arnaldo Carvalho de Melo wrote:
> > From: Arnaldo Carvalho de Melo <acme@redhat.com>
> > 
> > For cases where implicit fall through case labels are intended,
> > to let us inform that to gcc >= 7:
> 
> I believe this should be added to compiler_gcc.h

We still don't have it in tools/include/linux, but yeah, its a good idea
to have the equivalent of include/linux/compiler-gcc.h.

Then, at some point, the kernel can grab the definition from tools, i.e.
when people start trying to build the kernel _and_ this specific warning
is enabled there, as it is in tools/.

- Arnaldo
 
> > diff --git a/tools/include/linux/compiler.h b/tools/include/linux/compiler.h
> []
> > @@ -126,4 +126,13 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
> >  #define WRITE_ONCE(x, val) \
> >  	({ union { typeof(x) __val; char __c[1]; } __u = { .__val = (val) }; __write_once_size(&(x), __u.__c, sizeof(x)); __u.__val; })
> >  
> > +
> > +#ifndef __fallthrough
> > +# if defined(__GNUC__) && __GNUC__ >= 7
> > +#  define __fallthrough __attribute__ ((fallthrough))
> > +# else
> > +#  define __fallthrough
> > +# endif
> > +#endif
> > +
> >  #endif /* _TOOLS_LINUX_COMPILER_H */