linux-kernel - Re: [PATCH] gpio: sim: don't fiddle with GPIOLIB private members

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Message-ID: <ZPJTT/l9fX1lhu6O@smile.fi.intel.com>
Date:   Sat, 2 Sep 2023 00:10:39 +0300
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] gpio: sim: don't fiddle with GPIOLIB private members

On Fri, Sep 01, 2023 at 08:32:40PM +0200, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> 
> We access internals of struct gpio_device and struct gpio_desc because
> it's easier but it can actually be avoided and we're working towards a
> better encapsulation of GPIO data structures across the kernel so let's
> start at home.
> 
> Instead of checking gpio_desc flags, let's just track the requests of
> GPIOs in the driver. We also already store the information about
> direction of simulated lines.
> 
> For kobjects needed by sysfs callbacks: we can leverage the fact that
> once created for a software node, struct device is accessible from that
> fwnode_handle. We don't need to dereference gpio_device.
> 
> While at it: fix one line break and remove the untrue part about
> configfs callbacks using dev_get_drvdata() from a comment.

...

> -static void gpio_sim_free(struct gpio_chip *gc, unsigned int offset)

Why is this?

> +static int gpio_sim_request(struct gpio_chip *gc, unsigned int offset)
>  {
>  	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
>  
>  	scoped_guard(mutex, &chip->lock)
> +		__set_bit(offset, chip->request_map);
> +
> +	return 0;
> +}
> +
> +static void gpio_sim_free(struct gpio_chip *gc, unsigned int offset)
> +{
> +	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
> +
> +	scoped_guard(mutex, &chip->lock) {
>  		__assign_bit(offset, chip->value_map,
>  			     !!test_bit(offset, chip->pull_map));
> +		__clear_bit(offset, chip->request_map);
> +	}
>  }

Seems to me like you. shuffled the order of the two functions.
Can you leave _free() at the same location in the file?

...

> -	/* Used by sysfs and configfs callbacks. */
> -	dev_set_drvdata(&gc->gpiodev->dev, chip);
> +	/* Used by sysfs callbacks. */
> +	dev_set_drvdata(swnode->dev, chip);

dev pointer of firmware node is solely for dev links. Is it the case here?
Seems to me you luckily abuse it.

-- 
With Best Regards,
Andy Shevchenko