Re: [PATCH] gpiolib: fix bitmap operations related to line event watching

[Kent Gibson <warthog618@xxxxxxxxx>]

On Wed, Feb 26, 2020 at 02:53:23PM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
> 
> When operating on the bits of watched_lines bitmap, we're using
> desc_to_gpio() which returns the GPIO number from the global numberspace.
> This leads to all sorts of memory corruptions and invalid behavior. We
> should switch to using gpio_chip_hwgpio() instead.
> 
> Fixes: 51c1064e82e7 ("gpiolib: add new ioctl() for monitoring changes in line info")
> Reported-by: Kent Gibson <warthog618@xxxxxxxxx>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>

That fixes all the failures I was seeing.

Tested-by: Kent Gibson <warthog618@xxxxxxxxx>

> ---
>  drivers/gpio/gpiolib.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
> index a5cd1b4abe6f..5cc80f6f79e0 100644
> --- a/drivers/gpio/gpiolib.c
> +++ b/drivers/gpio/gpiolib.c
> @@ -1261,7 +1261,7 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  			return -EFAULT;
>  
>  		if (cmd == GPIO_GET_LINEINFO_WATCH_IOCTL)
> -			set_bit(desc_to_gpio(desc), priv->watched_lines);
> +			set_bit(gpio_chip_hwgpio(desc), priv->watched_lines);
>  
>  		return 0;
>  	} else if (cmd == GPIO_GET_LINEHANDLE_IOCTL) {
> @@ -1276,7 +1276,7 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
>  		if (IS_ERR(desc))
>  			return PTR_ERR(desc);
>  
> -		clear_bit(desc_to_gpio(desc), priv->watched_lines);
> +		clear_bit(gpio_chip_hwgpio(desc), priv->watched_lines);
>  		return 0;
>  	}
>  	return -EINVAL;
> @@ -1304,7 +1304,7 @@ static int lineinfo_changed_notify(struct notifier_block *nb,
>  	struct gpio_desc *desc = data;
>  	int ret;
>  
> -	if (!test_bit(desc_to_gpio(desc), priv->watched_lines))
> +	if (!test_bit(gpio_chip_hwgpio(desc), priv->watched_lines))
>  		return NOTIFY_DONE;
>  
>  	memset(&chg, 0, sizeof(chg));
> -- 
> 2.25.0
>