Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Tue, 28 Nov 2017 22:25:40 +0100 (CET)
From:   Thomas Gleixner <tglx@linutronix.de>
To:     "Gustavo A. R. Silva" <garsilva@embeddedor.com>
cc:     Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
        Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, x86@kernel.org,
        LKML <linux-kernel@vger.kernel.org>,
        Kees Cook <keescook@chromium.org>
Subject: Re: [PATCH] x86/syscalls: Mark expected switch fall-throughs
In-Reply-To: <20171128142532.Horde.i2oBtHDOaD7XV1M3yAL7rga@gator4166.hostgator.com>
Message-ID: <alpine.DEB.2.20.1711282220200.2222@nanos>
References: <20171127235253.GA20384@embeddedor.com> <alpine.DEB.2.20.1711281448520.1723@nanos> <20171128120512.Horde.1mz61Up1PsNtyHbrjWmK8L7@gator4166.hostgator.com> <alpine.DEB.2.20.1711281908040.2222@nanos> <alpine.DEB.2.20.1711281911280.2222@nanos>
 <20171128122235.Horde.vFP-9ZfAP0f9BFNePB8Z8xi@gator4166.hostgator.com> <alpine.DEB.2.20.1711281924080.2222@nanos> <alpine.DEB.2.20.1711281933170.2222@nanos> <20171128190032.2b1fa464@alans-desktop> <alpine.DEB.2.20.1711282109060.2222@nanos>
 <20171128142532.Horde.i2oBtHDOaD7XV1M3yAL7rga@gator4166.hostgator.com>
User-Agent: Alpine 2.20 (DEB 67 2015-01-07)
MIME-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, 28 Nov 2017, Gustavo A. R. Silva wrote:
> The thing about taking 'any comment' as valid is false if you add the
> following to your Makefile:
> 
> KBUILD_CFLAGS  += $(call cc-option,-Wimplicit-fallthrough)
> 
> This option takes the following comments as valid:
> 
> /* fall through */
> /* Fall through */
> /* fall through - ... */
> /* Fall through - ... */
> 
> Comments as fallthru, fallthrough, FALLTHRU are invalid.
> 
> And of course if you intentionally change the option to:
> 
> KBUILD_CFLAGS  += $(call cc-option,-Wimplicit-fallthrough=1)
> 
> it means that you obviously want to ignore any warning.

So I have to ask WHY this information was not in the changelog of the patch
in question:

   1) How it works

   2) Why comments have been chosen over macros

> In preparation to enabling -Wimplicit-fallthrough, mark switch cases
> where we are expecting to fall through.

It's not a reviewers job to chase that information down.

While I can understand that the comments are intentional due to existing
tools, I still prefer the macro/annotation. But I'm not religious about it
when there is common consensus. :)

Thanks,

	tglx

From 1585343630921733857@xxx Tue Nov 28 20:38:23 +0000 2017
X-GM-THRID: 1585265423856272058
X-Gmail-Labels: Inbox,Category Forums,HistoricalUnread