linux-kernel - Re: [PATCH v7 01/16] pinctrl: check the return value of pinmux_ops::get_function

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Message-ID: <CAMRc=Mfx5czDM=vfEYhFtVO3MviYaW4wKBYjGZ9ZnMbr-+T4mg@mail.gmail.com>
Date: Tue, 2 Sep 2025 15:29:31 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Andy Shevchenko <andriy.shevchenko@...el.com>
Cc: 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>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>, 
	"Liam R. Howlett" <Liam.Howlett@...cle.com>, Vlastimil Babka <vbabka@...e.cz>, 
	Mike Rapoport <rppt@...nel.org>, Suren Baghdasaryan <surenb@...gle.com>, Michal Hocko <mhocko@...e.com>, 
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	Shawn Guo <shawnguo@...nel.org>, Jacky Bai <ping.bai@....com>, 
	Pengutronix Kernel Team <kernel@...gutronix.de>, NXP S32 Linux Team <s32@....com>, 
	Sascha Hauer <s.hauer@...gutronix.de>, Tony Lindgren <tony@...mide.com>, 
	Haojian Zhuang <haojian.zhuang@...aro.org>, Geert Uytterhoeven <geert+renesas@...der.be>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, "Rafael J. Wysocki" <rafael@...nel.org>, 
	Danilo Krummrich <dakr@...nel.org>, Neil Armstrong <neil.armstrong@...aro.org>, 
	Mark Brown <broonie@...nel.org>, 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>, stable@...r.kernel.org
Subject: Re: [PATCH v7 01/16] pinctrl: check the return value of pinmux_ops::get_function_name()

On Tue, Sep 2, 2025 at 3:06 PM Andy Shevchenko
<andriy.shevchenko@...el.com> wrote:
>
> On Tue, Sep 02, 2025 at 01:59:10PM +0200, Bartosz Golaszewski wrote:
> > From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> >
> > While the API contract in docs doesn't specify it explicitly,
>
> So, why not to amend the doc at the same time?
>

Because this series is already big as is. That would be another commit
that can be separate.

> > the generic implementation of the get_function_name() callback from struct
> > pinmux_ops - pinmux_generic_get_function_name() - can fail and return
> > NULL. This is already checked in pinmux_check_ops() so add a similar
> > check in pinmux_func_name_to_selector() instead of passing the returned
> > pointer right down to strcmp() where the NULL can get dereferenced. This
> > is normal operation when adding new pinfunctions.
>
> Fixes?

This has always been like that.

> Reported?

I mean, technically Mark Brown reported my previous patch failing but
I don't think we do this if we're still within the same series just
another iteration?

> Closes?

Ditto.

>
> ...
>
> >       while (selector < nfuncs) {
> >               const char *fname = ops->get_function_name(pctldev, selector);
> >
> > -             if (!strcmp(function, fname))
> > +             if (fname && !strcmp(function, fname))
> >                       return selector;
>
> I would slightly refactor this:
>
>                 const char *fname;
>
>                 fname = ops->get_function_name(pctldev, selector);
>                 if (fname && !strcmp(function, fname))
>                         return selector;
>
> >               selector++;
>

You can do this in a subsequent patch, I prefer a smaller diff personally.

Bartosz