linux-kernel - Re: [PATCH] media: v4l2-dev: Check that g/s_selection are valid before selecting crop

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Date:   Tue, 07 Nov 2023 15:33:17 -0500
From:   Nicolas Dufresne <nicolas.dufresne@...labora.com>
To:     Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Sakari Ailus <sakari.ailus@....fi>,
        Hans Verkuil <hverkuil@...all.nl>
Subject: Re: [PATCH] media: v4l2-dev: Check that g/s_selection are valid
 before selecting crop

Le mardi 07 novembre 2023 à 21:05 +0100, Paul Kocialkowski a écrit :
> The cropcap and g/s_crop ioctls are automatically marked as valid whenever the
> g/s_selection ops are filled. The rationale is to auto-enable these legacy
> cropcap and g/s_crop ioctls that rely on g/s_selection.
> 
> However it's possible that the ops are filled but explicitly disabled with
> calls to v4l2_disable_ioctl. In this situation the legacy ioctls should not
> be enabled.
> 
> Add a check on the video device's valid ioctls field before auto-selecting
> them to honor the driver's choice. Note that the meaning of the bitfield
> stored in the video device is the opposite of what the name suggests as
> v4l2_disable_ioctl will set the bits. Their meaning will be reversed at
> the end of the function.
> 
> Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>

Reviewed-by: Nicolas Dufresne <nicolas.dufresne@...labora.com>

> ---
>  drivers/media/v4l2-core/v4l2-dev.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/media/v4l2-core/v4l2-dev.c b/drivers/media/v4l2-core/v4l2-dev.c
> index f81279492682..d13954bd31fd 100644
> --- a/drivers/media/v4l2-core/v4l2-dev.c
> +++ b/drivers/media/v4l2-core/v4l2-dev.c
> @@ -642,11 +642,13 @@ static void determine_valid_ioctls(struct video_device *vdev)
>  		SET_VALID_IOCTL(ops, VIDIOC_TRY_DECODER_CMD, vidioc_try_decoder_cmd);
>  		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FRAMESIZES, vidioc_enum_framesizes);
>  		SET_VALID_IOCTL(ops, VIDIOC_ENUM_FRAMEINTERVALS, vidioc_enum_frameintervals);
> -		if (ops->vidioc_g_selection) {
> +		if (ops->vidioc_g_selection &&
> +		    !test_bit(_IOC_NR(VIDIOC_G_SELECTION), vdev->valid_ioctls)) {
>  			__set_bit(_IOC_NR(VIDIOC_G_CROP), valid_ioctls);
>  			__set_bit(_IOC_NR(VIDIOC_CROPCAP), valid_ioctls);
>  		}
> -		if (ops->vidioc_s_selection)
> +		if (ops->vidioc_s_selection &&
> +		    !test_bit(_IOC_NR(VIDIOC_S_SELECTION), vdev->valid_ioctls))
>  			__set_bit(_IOC_NR(VIDIOC_S_CROP), valid_ioctls);
>  		SET_VALID_IOCTL(ops, VIDIOC_G_SELECTION, vidioc_g_selection);
>  		SET_VALID_IOCTL(ops, VIDIOC_S_SELECTION, vidioc_s_selection);