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

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

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

> > 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;

-- 
Regards,

Laurent Pinchart