Re: [PATCH] media: uvcvideo: drop useless assignment in uvc_parse_format()

[Hans de Goede <hansg@kernel.org>]

Hi,

On 28-Sep-26 22:29, Laurent Pinchart wrote:
> On Thu, Aug 27, 2026 at 11:24:33AM +0200, Ricardo Ribalda wrote:
>> Hi Sergey
>>
>> On Thu, 20 Aug 2026 at 22:12, Sergey Shtylyov <s.shtylyov@auroraos.dev> wrote:
>>>
>>> Close to the end of uvc_parse_format(), the parameter buflen is decremented
>>> (again) but that statement seems pointless as buflen isn't used afterwards.
>>> Drop the useless assignment (gcc doesn't generate any code for it anyways).
>>
>> The patch is correct, although I do not see a great benefit in
>> removing it. As you say, the compiler will remove it anyway. If we
>> modify the function to add logging or continue parsing the left over
>> buffer, it is going to come back to haunt us....
>>
>> I leave it to Laurent or HansG to decide if they want to merge it.
> 
> I'd rather keep the buflen update in place for the reasons explained by
> Ricardo.
> 
> /me wishes for std::span<> in C

Ack, I've dropped this patch from patchwork.

Regards,

Hans


> 
>>> Found by Linux Verification Center (linuxtesting.org) with the Svace static
>>> analysis tool.
>>>
>>> Signed-off-by: Sergey Shtylyov <s.shtylyov@auroraos.dev>
>>> ---
>>>  drivers/media/usb/uvc/uvc_driver.c | 1 -
>>>  1 file changed, 1 deletion(-)
>>>
>>> diff --git a/drivers/media/usb/uvc/uvc_driver.c b/drivers/media/usb/uvc/uvc_driver.c
>>> index e289cc71ba98..0e78e8bcd320 100644
>>> --- a/drivers/media/usb/uvc/uvc_driver.c
>>> +++ b/drivers/media/usb/uvc/uvc_driver.c
>>> @@ -520,7 +520,6 @@ static int uvc_parse_format(struct uvc_device *dev,
>>>                 format->xfer_func = uvc_xfer_func(buffer[4]);
>>>                 format->ycbcr_enc = uvc_ycbcr_enc(buffer[5]);
>>>
>>> -               buflen -= buffer[0];
>>>                 buffer += buffer[0];
>>>         } else {
>>>                 format->colorspace = V4L2_COLORSPACE_SRGB;
>