linux-hardening - Re: [PATCH v3 01/15] lib: provide kmemdup

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Message-ID: <aIIef0MDcZiElgN1@smile.fi.intel.com>
Date: Thu, 24 Jul 2025 14:52:31 +0300
From: Andy Shevchenko <andriy.shevchenko@...el.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andy Shevchenko <andy.shevchenko@...il.com>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bjorn Andersson <andersson@...nel.org>,
	Konrad Dybcio <konradybcio@...nel.org>,
	Alexey Klimov <alexey.klimov@...aro.org>,
	Lorenzo Bianconi <lorenzo@...nel.org>,
	Sean Wang <sean.wang@...nel.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	Paul Cercueil <paul@...pouillou.net>, Kees Cook <kees@...nel.org>,
	Andy Shevchenko <andy@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...hat.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
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	Jacky Bai <ping.bai@....com>,
	Pengutronix Kernel Team <kernel@...gutronix.de>,
	NXP S32 Linux Team <s32@....com>,
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	Haojian Zhuang <haojian.zhuang@...aro.org>,
	Geert Uytterhoeven <geert+renesas@...der.be>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, linux-mediatek@...ts.infradead.org,
	linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
	linux-hardening@...r.kernel.org, linux-mm@...ck.org,
	imx@...ts.linux.dev, linux-omap@...r.kernel.org,
	linux-renesas-soc@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v3 01/15] lib: provide kmemdup_const()

On Thu, Jul 24, 2025 at 12:15:11PM +0100, Lorenzo Stoakes wrote:
> On Thu, Jul 24, 2025 at 01:12:49PM +0200, Andy Shevchenko wrote:
> > On Thu, Jul 24, 2025 at 1:10 PM Lorenzo Stoakes
> > <lorenzo.stoakes@...cle.com> wrote:
> > > On Thu, Jul 24, 2025 at 11:24:29AM +0200, Bartosz Golaszewski wrote:
> > > > +extern const void *kmemdup_const(const void *src, size_t len, gfp_t gfp);
> > >
> > > Please drop extern, it's unnecessary.
> >
> > It's all over the header. This should be done as a precursor patch and
> > I know that usually people push back on doing that. I gave up on this.
> > Kernel is going to rot sooner or later... :-(
> 
> In mm we just update as we go, this is probably the best approach to avoid
> unnecessary churn.

I agree on the idea of eliminating it, but also I agree on the consistency over
redundancy. That's why I prefer to see this done at once for all (in the same
header) than doing one-by-one. And this approach got a lot of pushes back, while
the former even more pushed back on the (in)consistency matters.

-- 
With Best Regards,
Andy Shevchenko