linux-kernel - Re: [PATCH v1 1/5] gpiolib: fix linker errors when GPIOLIB is disabled

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Message-ID: <Y9JTo1RkxT2jORPE@smile.fi.intel.com>
Date:   Thu, 26 Jan 2023 12:19:15 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Christophe Leroy <christophe.leroy@...roup.eu>
Cc:     Bartosz Golaszewski <bartosz.golaszewski@...aro.org>,
        Dmitry Torokhov <dmitry.torokhov@...il.com>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Arnd Bergmann <arnd@...db.de>,
        Pierluigi Passaro <pierluigi.p@...iscite.com>,
        kernel test robot <lkp@...el.com>
Subject: Re: [PATCH v1 1/5] gpiolib: fix linker errors when GPIOLIB is
 disabled

On Thu, Jan 26, 2023 at 08:14:49AM +0000, Christophe Leroy wrote:
> Le 25/01/2023 à 21:10, Andy Shevchenko a écrit :
> > From: Pierluigi Passaro <pierluigi.p@...iscite.com>
> > 
> > Both the functions gpiochip_request_own_desc and
> > gpiochip_free_own_desc are exported from
> >      drivers/gpio/gpiolib.c
> > but this file is compiled only when CONFIG_GPIOLIB is enabled.
> > Move the prototypes under "#ifdef CONFIG_GPIOLIB" and provide
> > reasonable definitions and includes in the "#else" branch.
> 
> Can you give more details on when and why link fails ?
> 
> You are adding a WARN(), I understand it mean the function should never 
> ever be called. Shouldn't it be dropped completely by the compiler ? In 
> that case, no call to gpiochip_request_own_desc() should be emitted and 
> so link should be ok.
> 
> If link fails, it means we still have unexpected calls to 
> gpiochip_request_own_desc() or gpiochip_free_own_desc(), and we should 
> fix the root cause instead of hiding it with a WARN().

I agree, but what do you suggest exactly? I think the calls to that functions
shouldn't be in the some drivers as it's layering violation (they are not a
GPIO chips to begin with). Simply adding a dependency not better than this one.

-- 
With Best Regards,
Andy Shevchenko