On 28/05/2024 04:04, Nas Chung wrote:
> Explicitly compare a buffer type only with valid buffer types,
> to avoid matching the buffer type outside of valid buffer
> type set.
>
> Signed-off-by: Nas Chung <nas.chung@xxxxxxxxxxxxxxx>
> ---
> include/uapi/linux/videodev2.h | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index fe6b67e83751..fa2b7086e480 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -157,6 +157,10 @@ enum v4l2_buf_type {
> V4L2_BUF_TYPE_PRIVATE = 0x80,
> };
>
> +#define V4L2_TYPE_IS_VALID(type) \
> + ((type) >= V4L2_BUF_TYPE_VIDEO_CAPTURE \
> + && (type) <= V4L2_BUF_TYPE_META_OUTPUT)
> +
> #define V4L2_TYPE_IS_MULTIPLANAR(type) \
> ((type) == V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE \
> || (type) == V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE)
> @@ -171,7 +175,8 @@ enum v4l2_buf_type {
> || (type) == V4L2_BUF_TYPE_SDR_OUTPUT \
> || (type) == V4L2_BUF_TYPE_META_OUTPUT)
>
> -#define V4L2_TYPE_IS_CAPTURE(type) (!V4L2_TYPE_IS_OUTPUT(type))
> +#define V4L2_TYPE_IS_CAPTURE(type) \
> + (V4L2_TYPE_IS_VALID(type) && !V4L2_TYPE_IS_OUTPUT(type))
>
> enum v4l2_tuner_type {
> V4L2_TUNER_RADIO = 1,
This patch introduced this warning:
In function 'find_format_by_index',
inlined from 'vdec_enum_fmt' at drivers/media/platform/qcom/venus/vdec.c:452:8:
drivers/media/platform/qcom/venus/vdec.c:172:32: warning: 'valid' may be used uninitialized [-Wmaybe-uninitialized]
172 | if (k == index && valid)
| ~~~~~~~~~~~^~~~~~~~
drivers/media/platform/qcom/venus/vdec.c: In function 'vdec_enum_fmt':
drivers/media/platform/qcom/venus/vdec.c:157:22: note: 'valid' was declared here
157 | bool valid;
| ^~~~~
This driver does this:
bool valid;
if (V4L2_TYPE_IS_OUTPUT(type)) {
valid = venus_helper_check_codec(inst, fmt[i].pixfmt);
} else if (V4L2_TYPE_IS_CAPTURE(type)) {
valid = venus_helper_check_format(inst, fmt[i].pixfmt);
With your patch both V4L2_TYPE_IS_OUTPUT(type) and V4L2_TYPE_IS_CAPTURE(type)
can return false, something that wasn't possible without this patch.
In this driver the fix would just be to drop the second 'if' altogether, so just
'} else {'.
Since these defines are part of the public API, this change introduces a subtle
behavior difference that can affect applications.
That said, I do consider this an improvement.
I would like some changes, though:
1) Just after "V4L2_BUF_TYPE_META_OUTPUT = 14," in enum v4l2_buf_type,
add a comment saying that V4L2_TYPE_IS_VALID and (for output types)
V4L2_TYPE_IS_OUTPUT must be updated if a new type is added. It's all
too easy to forget that otherwise.
2) Add a patch fixing the venus/vdec.c code.
3) Something else I noticed, but I think this change should be in a separate patch:
V4L2_TYPE_IS_OUTPUT() returns true for V4L2_BUF_TYPE_VIDEO_OVERLAY, but that
definitely belongs to CAPTURE. Nobody really uses that type anymore, but still,
it should be fixed.
Regards,
Hans
