Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Message-ID: <2fd265ec46a8b582b7c5dea9524185b6fe1b0322.camel@sipsolutions.net>
Subject: Re: Use of void pointer arithmetic?
From:   Johannes Berg <johannes@sipsolutions.net>
To:     Kalle Valo <kvalo@kernel.org>,
        Dan Carpenter <dan.carpenter@oracle.com>
Cc:     Francesco Magliocca <franciman12@gmail.com>,
        Jeff Johnson <quic_jjohnson@quicinc.com>,
        ath10k@lists.infradead.org, rmanohar@qti.qualcomm.com,
        linux-wireless@vger.kernel.org, linux-kernel@vger.kernel.org,
        Linus Torvalds <torvalds@linuxfoundation.org>
Date:   Thu, 24 Feb 2022 11:31:12 +0100
In-Reply-To: <87fso8vb3w.fsf_-_@kernel.org>
References: <20220221122638.7971-1-franciman12@gmail.com>
         <e32de43c-e00a-5766-e988-fe192d36d719@quicinc.com>
         <CAH4F6utmtAM3CzX2_Fbn94Sb-X8m0patPh8yWwbuBB0t1VYH=g@mail.gmail.com>
         <87o82wvhtk.fsf@kernel.org> <20220224075346.GL3943@kadam>
         <87fso8vb3w.fsf_-_@kernel.org>
Content-Type: text/plain; charset="UTF-8"
User-Agent: Evolution 3.42.4 (3.42.4-1.fc35) 
MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Precedence: bulk

On Thu, 2022-02-24 at 11:59 +0200, Kalle Valo wrote:
> 
> A good question. I have always just thought we should avoid void pointer
> arithmetic due to the C standard, but now that you mention it void
> pointers can indeed simplify the code. So I'm not so sure anymore.
> 
> Any opinions? Is there a kernel wide recommendation for this?

The kernel only enables it with W=3, which I guess nobody uses anyway
... Originally it came from commit 4a5838ad9d2d ("kbuild: Add extra gcc
checks") with a pointer to

http://marc.info/?l=kernel-janitors&m=129802065918147&w=2

(which is offline right now due to an expired certificate ...)

but setting back my clock it seems to point to

https://lore.kernel.org/all/20110218091716.GA4384@bicker/

but the thread kind of revolves around -Wconversion.


FreeBSD does enable -Wpointer-arith which is why we've been trying to
keep iwlwifi clean as a courtesy to them, but for really Linux-only code
I dunno if there's much point. Although of course that applies also to
FreeBSD ...

johannes