linux-kernel - Re: [PATCH v5 08/12] gpio: aggregator: export symbols of the GPIO forwarder library

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Message-ID: <aCIBoSi84NnwEA2s@smile.fi.intel.com>
Date: Mon, 12 May 2025 17:11:45 +0300
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Thomas Richard <thomas.richard@...tlin.com>
Cc: Geert Uytterhoeven <geert@...ux-m68k.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>, Kees Cook <kees@...nel.org>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	thomas.petazzoni@...tlin.com, DanieleCleri@...on.eu,
	GaryWang@...on.com.tw, linux-hardening@...r.kernel.org
Subject: Re: [PATCH v5 08/12] gpio: aggregator: export symbols of the GPIO
 forwarder library

On Mon, May 12, 2025 at 04:08:35PM +0200, Thomas Richard wrote:
> On 5/9/25 11:07, Geert Uytterhoeven wrote:
> > On Tue, 6 May 2025 at 17:21, Thomas Richard <thomas.richard@...tlin.com> wrote:

...

> >> +int gpio_fwd_set_config(struct gpio_chip *chip, unsigned int offset,
> >> +                       unsigned long config);
> >> +
> >> +int gpio_fwd_to_irq(struct gpio_chip *chip, unsigned int offset);
> > 
> > I would expect all of these to take gpiochip_fwd pointers instead of
> > gpio_chip pointers.  What prevents you from passing a gpio_chip pointer
> > that does not correspond to a gpiochip_fwd object, causing a crash?
> 
> Indeed nothing prevents from passing gpio_chip pointer which does not
> correspond to a gpiochip_fwd object.
> And it is also a bit weird to pass a gpiochip_fwd pointer in some cases
> (for example gpio_fwd_gpio_add()) and a gpio_chip in other cases.
> 
> I can keep GPIO operations as is, and create exported wrappers which
> take a gpiochip_fwd pointer as parameter, for example:
> 
> int gpiochip_fwd_get_multiple(struct gpiochip_fwd *fwd,
> 			      unsigned long *mask,
> 			      unsigned long *bits)
> {
> 	struct gpio_chip *gc = gpiochip_fwd_get_gpiochip(fwd);
> 
> 	return gpio_fwd_get_multiple_locked(chip, mask, bits);
> }
> EXPORT_SYMBOL_NS_GPL(gpiochip_fwd_get_multiple, "GPIO_FORWARDER");
> 
> So exported functions are gpiochip_fwd_*().

Sounds good for me. Let's wait for Geert's opinoin on this.

-- 
With Best Regards,
Andy Shevchenko