linux-kernel - Re: Use of void pointer arithmetic?

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Message-ID: <2fd265ec46a8b582b7c5dea9524185b6fe1b0322.camel@sipsolutions.net>
Date:   Thu, 24 Feb 2022 11:31:12 +0100
From:   Johannes Berg <johannes@...solutions.net>
To:     Kalle Valo <kvalo@...nel.org>,
        Dan Carpenter <dan.carpenter@...cle.com>
Cc:     Francesco Magliocca <franciman12@...il.com>,
        Jeff Johnson <quic_jjohnson@...cinc.com>,
        ath10k@...ts.infradead.org, rmanohar@....qualcomm.com,
        linux-wireless@...r.kernel.org, linux-kernel@...r.kernel.org,
        Linus Torvalds <torvalds@...uxfoundation.org>
Subject: Re: Use of void pointer arithmetic?

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