linux-kernel - Re: [PATCH v1 1/2] gpiolib: Never return internal error codes to user space

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Date:   Wed, 19 May 2021 07:24:51 +0800
From:   Kent Gibson <warthog618@...il.com>
To:     Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Suresh Balakrishnan <suresh.balakrishnan@...el.com>
Subject: Re: [PATCH v1 1/2] gpiolib: Never return internal error codes to
 user space

On Tue, May 18, 2021 at 06:50:12PM +0300, Andy Shevchenko wrote:
> Currently it's possible that character device interface may return
> the error codes which are not supposed to be seen by user space.
> In this case it's EPROBE_DEFER.
> 
> Wrap it to return -ENODEV instead as sysfs does.
> 
> Fixes: d7c51b47ac11 ("gpio: userspace ABI for reading/writing GPIO lines")
> Fixes: 61f922db7221 ("gpio: userspace ABI for reading GPIO line events")
> Fixes: 3c0d9c635ae2 ("gpiolib: cdev: support GPIO_V2_GET_LINE_IOCTL and GPIO_V2_LINE_GET_VALUES_IOCTL")
> Reported-by: Suresh Balakrishnan <suresh.balakrishnan@...el.com>
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
> ---
>  drivers/gpio/gpiolib-cdev.c | 15 ++++++++++++---
>  1 file changed, 12 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c
> index 1631727bf0da..1d8f66880d63 100644
> --- a/drivers/gpio/gpiolib-cdev.c
> +++ b/drivers/gpio/gpiolib-cdev.c
> @@ -331,8 +331,11 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
>  		}
>  
>  		ret = gpiod_request(desc, lh->label);
> -		if (ret)
> +		if (ret) {
> +			if (ret == -EPROBE_DEFER)
> +				ret = -ENODEV;
>  			goto out_free_lh;
> +		}
>  		lh->descs[i] = desc;
>  		linehandle_flags_to_desc_flags(handlereq.flags, &desc->flags);
>  
> @@ -1379,8 +1382,11 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip)
>  		}
>  
>  		ret = gpiod_request(desc, lr->label);
> -		if (ret)
> +		if (ret) {
> +			if (ret == -EPROBE_DEFER)
> +				ret = -ENODEV;
>  			goto out_free_linereq;
> +		}
>  
>  		lr->lines[i].desc = desc;
>  		flags = gpio_v2_line_config_flags(lc, i);
> @@ -1765,8 +1771,11 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
>  	}
>  
>  	ret = gpiod_request(desc, le->label);
> -	if (ret)
> +	if (ret) {
> +		if (ret == -EPROBE_DEFER)
> +			ret = -ENODEV;
>  		goto out_free_le;
> +	}
>  	le->desc = desc;
>  	le->eflags = eflags;
>  

You immediately revert this patch in patch 2.
My understanding is that is not allowed within a patch set.
Why split the patches instead of going direct to the new helper?

Cheers,
Kent.