Re: [PATCH 5/5] gpio: cdev: don't overwrite the whole flags field when configuring lines

[Andy Shevchenko]

On Wed, Nov 04, 2026 at 04:37:00PM +0100, Bartosz Golaszewski wrote:
> linehandle_flags_to_desc_flags() and
> gpio_v2_line_config_flags_to_desc_flags() read the flags word with
> READ_ONCE(), modify the local copy and write it back with WRITE_ONCE().
> 
> The per-request config_mutex does not exclude sysfs, the irq core or
> drivers touching the same descriptor, so bits they set or clear
> concurrently can be lost.
> 
> Build the mask of bits owned by the line configuration and their new
> values locally and apply them with gpiod_update_flags(). The whole
> group changes in a single atomic step.

...

> -	unsigned long flags = READ_ONCE(*flagsp);

> +	unsigned long val = 0;

Why variable renaming?

...

> +{
> +	const unsigned long mask = BIT(GPIOD_FLAG_ACTIVE_LOW) |
> +				   BIT(GPIOD_FLAG_EDGE_RISING) |
> +				   BIT(GPIOD_FLAG_EDGE_FALLING) |
> +				   BIT(GPIOD_FLAG_OPEN_DRAIN) |
> +				   BIT(GPIOD_FLAG_OPEN_SOURCE) |
> +				   BIT(GPIOD_FLAG_PULL_UP) |
> +				   BIT(GPIOD_FLAG_PULL_DOWN) |
> +				   BIT(GPIOD_FLAG_BIAS_DISABLE) |
> +				   BIT(GPIOD_FLAG_EVENT_CLOCK_REALTIME) |
> +				   BIT(GPIOD_FLAG_EVENT_CLOCK_HTE);
> +	unsigned long val = 0;

Ditto.

-- 
With Best Regards,
Andy Shevchenko