Re: [PATCH RFC] gpio: sim: access sysfs attributes as const

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:
- [Low] gpio-sim: incomplete sysfs attribute constification
--

commit 055dde35eca9fff8d54ca501f4fca6d98889dfd8
Author: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>

gpio: sim: access sysfs attributes as const

Use the const variant of constainer_of() to access struct
gpio_sim_attribute which wraps the dynamically allocated sysfs
attributes for value and pull of simulated GPIO lines in line with the
currently preferred approach.

> diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
> index 0c73bec042670..e0ae586cd08d8 100644
> --- a/drivers/gpio/gpio-sim.c
> +++ b/drivers/gpio/gpio-sim.c
> @@ -59,10 +59,10 @@ struct gpio_sim_attribute {
>  	unsigned int offset;
>  };
>  
> -static struct gpio_sim_attribute *
> +static const struct gpio_sim_attribute *
>  to_gpio_sim_attr(struct device_attribute *dev_attr)

[Severity: Low]
Does this function signature need to be updated to take a const
struct device_attribute *dev_attr?

Since dev_attr is still non-const here, the container_of_const macro will
evaluate its non-const branch, resulting in a non-const pointer that gets
implicitly cast to const by the return statement. This makes the generic type
selection of container_of_const largely redundant.

>  {
> -	return container_of(dev_attr, struct gpio_sim_attribute, dev_attr);
> +	return container_of_const(dev_attr, struct gpio_sim_attribute, dev_attr);
>  }

[ ... ]

> @@ -272,7 +272,7 @@ static void gpio_sim_dbg_show(struct seq_file *seq, struct gpio_chip *gc)
>  static ssize_t gpio_sim_sysfs_val_show(struct device *dev,
>  				       struct device_attribute *attr, char *buf)

[Severity: Low]
Should these sysfs callback signatures be updated to accept a const struct
device_attribute *attr?

The callbacks still accept a non-const attr parameter, meaning the refactoring
to const attributes is incomplete.

For a full migration, the callback signatures should accept const struct
device_attribute *attr and be assigned to the appropriate show_const /
store_const function pointers in the attribute definition.

>  {
> -	struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
> +	const struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
>  	struct gpio_sim_chip *chip = dev_get_drvdata(dev);
>  	int val;

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261016-gpio-sim-const-sysfs-attr-v1-1-5d2f832890d6@oss.qualcomm.com?part=1