linux-kernel - Re: [PATCH v3 5/8] media: v4l2-core: return -ENODEV from ioctl when not registered

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Message-ID: <YMeMGbJqiRimgzxy@pendragon.ideasonboard.com>
Date:   Mon, 14 Jun 2021 20:04:25 +0300
From:   Laurent Pinchart <laurent.pinchart@...asonboard.com>
To:     Arnd Bergmann <arnd@...nel.org>
Cc:     Hans Verkuil <hverkuil-cisco@...all.nl>,
        Mauro Carvalho Chehab <mchehab@...nel.org>,
        Arnd Bergmann <arnd@...db.de>,
        "Lad, Prabhakar" <prabhakar.csengg@...il.com>,
        Eduardo Valentin <edubezval@...il.com>,
        Sakari Ailus <sakari.ailus@...ux.intel.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Vaibhav Gupta <vaibhavgupta40@...il.com>,
        Liu Shixin <liushixin2@...wei.com>,
        Jacopo Mondi <jacopo+renesas@...ndi.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        linux-kernel@...r.kernel.org, linux-media@...r.kernel.org,
        linux-staging@...ts.linux.dev
Subject: Re: [PATCH v3 5/8] media: v4l2-core: return -ENODEV from ioctl when
 not registered

Hi Arnd,

Thank you for the patch.

On Mon, Jun 14, 2021 at 12:34:06PM +0200, Arnd Bergmann wrote:
> From: Arnd Bergmann <arnd@...db.de>
> 
> I spotted a minor difference is handling of unregistered devices
> between native and compat ioctls: the native handler never tries
> to call into the driver if a device is not marked as registered.
> 
> I did not check whether this can cause issues in the kernel, or
> just a different between return codes, but it clearly makes
> sense that both should behave the same way.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

Reviewed-by: Laurent Pinchart <laurent.pinchart@...asonboard.com>

> ---
>  drivers/media/v4l2-core/v4l2-compat-ioctl32.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> index 0ca75f6784c5..47aff3b19742 100644
> --- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> +++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> @@ -1244,6 +1244,9 @@ long v4l2_compat_ioctl32(struct file *file, unsigned int cmd, unsigned long arg)
>  	if (!file->f_op->unlocked_ioctl)
>  		return ret;
>  
> +	if (!video_is_registered(vdev))
> +		return -ENODEV;
> +
>  	if (_IOC_TYPE(cmd) == 'V' && _IOC_NR(cmd) < BASE_VIDIOC_PRIVATE)
>  		ret = file->f_op->unlocked_ioctl(file, cmd,
>  					(unsigned long)compat_ptr(arg));

-- 
Regards,

Laurent Pinchart