linux-kernel - Re: [PATCH] gpiolib: use __counted

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Message-ID: <ZYGyumQXaM8PXzcz@smile.fi.intel.com>
Date: Tue, 19 Dec 2023 17:11:54 +0200
From: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Linus Walleij <linus.walleij@...aro.org>,
	Kent Gibson <warthog618@...il.com>, linux-gpio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH] gpiolib: use __counted_by() for GPIO descriptors

On Tue, Dec 19, 2023 at 01:57:06PM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> Pull the array of GPIO descriptors into struct gpio_device as a flexible
> array and use __counted_by() to control its size.

How big is the struct gpio_device? Unifying like this might provoke subtle
errors on very fragmented memory, where k*alloc() might not find enough free
space. Note, k*alloc() guarantees finding only memory for a single page.
With PAGE_SIZE = 4k, this might be an issue.

I would suggest, if nothing prevents us from switching, to use kvmalloc().

-- 
With Best Regards,
Andy Shevchenko