Re: [RFCv4 10/21] videodev2.h: Add request_fd field to v4l2_buffer

[Hans Verkuil]

On 02/20/18 05:44, Alexandre Courbot wrote:
> From: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> 
> When queuing buffers allow for passing the request that should
> be associated with this buffer.
> 
> Signed-off-by: Hans Verkuil <hans.verkuil@xxxxxxxxx>
> [acourbot@xxxxxxxxxxxx: make request ID 32-bit]
> Signed-off-by: Alexandre Courbot <acourbot@xxxxxxxxxxxx>
> ---
>  drivers/media/common/videobuf2/videobuf2-v4l2.c | 2 +-
>  drivers/media/usb/cpia2/cpia2_v4l.c             | 2 +-
>  drivers/media/v4l2-core/v4l2-compat-ioctl32.c   | 9 ++++++---
>  drivers/media/v4l2-core/v4l2-ioctl.c            | 4 ++--
>  include/uapi/linux/videodev2.h                  | 3 ++-
>  5 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/media/common/videobuf2/videobuf2-v4l2.c b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> index 886a2d8d5c6c..6d4d184aa68e 100644
> --- a/drivers/media/common/videobuf2/videobuf2-v4l2.c
> +++ b/drivers/media/common/videobuf2/videobuf2-v4l2.c
> @@ -203,7 +203,7 @@ static void __fill_v4l2_buffer(struct vb2_buffer *vb, void *pb)
>  	b->timestamp = ns_to_timeval(vb->timestamp);
>  	b->timecode = vbuf->timecode;
>  	b->sequence = vbuf->sequence;
> -	b->reserved2 = 0;
> +	b->request_fd = 0;
>  	b->reserved = 0;
>  
>  	if (q->is_multiplanar) {
> diff --git a/drivers/media/usb/cpia2/cpia2_v4l.c b/drivers/media/usb/cpia2/cpia2_v4l.c
> index 99f106b13280..af42ce3ceb48 100644
> --- a/drivers/media/usb/cpia2/cpia2_v4l.c
> +++ b/drivers/media/usb/cpia2/cpia2_v4l.c
> @@ -948,7 +948,7 @@ static int cpia2_dqbuf(struct file *file, void *fh, struct v4l2_buffer *buf)
>  	buf->sequence = cam->buffers[buf->index].seq;
>  	buf->m.offset = cam->buffers[buf->index].data - cam->frame_buffer;
>  	buf->length = cam->frame_size;
> -	buf->reserved2 = 0;
> +	buf->request_fd = 0;
>  	buf->reserved = 0;
>  	memset(&buf->timecode, 0, sizeof(buf->timecode));
>  
> diff --git a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> index 5198c9eeb348..32bf47489a2e 100644
> --- a/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> +++ b/drivers/media/v4l2-core/v4l2-compat-ioctl32.c
> @@ -386,7 +386,7 @@ struct v4l2_buffer32 {
>  		__s32		fd;
>  	} m;
>  	__u32			length;
> -	__u32			reserved2;
> +	__s32			request_fd;
>  	__u32			reserved;
>  };
>  
> @@ -486,6 +486,7 @@ static int get_v4l2_buffer32(struct v4l2_buffer __user *kp,
>  {
>  	u32 type;
>  	u32 length;
> +	s32 request_fd;
>  	enum v4l2_memory memory;
>  	struct v4l2_plane32 __user *uplane32;
>  	struct v4l2_plane __user *uplane;
> @@ -500,7 +501,9 @@ static int get_v4l2_buffer32(struct v4l2_buffer __user *kp,
>  	    get_user(memory, &up->memory) ||
>  	    put_user(memory, &kp->memory) ||
>  	    get_user(length, &up->length) ||
> -	    put_user(length, &kp->length))
> +	    put_user(length, &kp->length) ||
> +	    get_user(request_fd, &up->request_fd) ||
> +	    put_user(request_fd, &kp->request_fd))
>  		return -EFAULT;
>  
>  	if (V4L2_TYPE_IS_OUTPUT(type))
> @@ -604,7 +607,7 @@ static int put_v4l2_buffer32(struct v4l2_buffer __user *kp,
>  	    assign_in_user(&up->timestamp.tv_usec, &kp->timestamp.tv_usec) ||
>  	    copy_in_user(&up->timecode, &kp->timecode, sizeof(kp->timecode)) ||
>  	    assign_in_user(&up->sequence, &kp->sequence) ||
> -	    assign_in_user(&up->reserved2, &kp->reserved2) ||
> +	    assign_in_user(&up->request_fd, &kp->request_fd) ||
>  	    assign_in_user(&up->reserved, &kp->reserved) ||
>  	    get_user(length, &kp->length) ||
>  	    put_user(length, &up->length))
> diff --git a/drivers/media/v4l2-core/v4l2-ioctl.c b/drivers/media/v4l2-core/v4l2-ioctl.c
> index 260288ca4f55..7bfeaf233d5a 100644
> --- a/drivers/media/v4l2-core/v4l2-ioctl.c
> +++ b/drivers/media/v4l2-core/v4l2-ioctl.c
> @@ -437,13 +437,13 @@ static void v4l_print_buffer(const void *arg, bool write_only)
>  	const struct v4l2_plane *plane;
>  	int i;
>  
> -	pr_cont("%02ld:%02d:%02d.%08ld index=%d, type=%s, flags=0x%08x, field=%s, sequence=%d, memory=%s",
> +	pr_cont("%02ld:%02d:%02d.%08ld index=%d, type=%s, request_fd=%u, flags=0x%08x, field=%s, sequence=%d, memory=%s",
>  			p->timestamp.tv_sec / 3600,
>  			(int)(p->timestamp.tv_sec / 60) % 60,
>  			(int)(p->timestamp.tv_sec % 60),
>  			(long)p->timestamp.tv_usec,
>  			p->index,
> -			prt_names(p->type, v4l2_type_names),
> +			prt_names(p->type, v4l2_type_names), p->request_fd,
>  			p->flags, prt_names(p->field, v4l2_field_names),
>  			p->sequence, prt_names(p->memory, v4l2_memory_names));
>  
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index 982718965180..4fd46ae8fad5 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -909,6 +909,7 @@ struct v4l2_plane {
>   * @length:	size in bytes of the buffer (NOT its payload) for single-plane
>   *		buffers (when type != *_MPLANE); number of elements in the
>   *		planes array for multi-plane buffers
> + * @request_fd: fd of the request that this buffer should use
>   *
>   * Contains data exchanged by application and driver using one of the Streaming
>   * I/O methods.
> @@ -932,7 +933,7 @@ struct v4l2_buffer {
>  		__s32		fd;
>  	} m;
>  	__u32			length;
> -	__u32			reserved2;
> +	__s32			request_fd;

This should be:

	union {
		__s32		request_fd;
		__u32		reserved2;
	};

Otherwise any existing application that sets 'reserved2 = 0;' would fail.
I encountered this issue when compiling v4l-utils.

Regards,

	Hans

>  	__u32			reserved;
>  };
>  
>