Re: [PATCH] usb: video: fix descriptor structures macros

[Greg KH <gregkh@linuxfoundation.org>]

On Thu, Feb 11, 2021 at 01:55:21PM +0100, Sylvain Pelissier wrote:
> Le jeu. 11 févr. 2021 à 13:48, Greg KH <gregkh@linuxfoundation.org> a
> écrit :
> 
> > On Tue, Feb 09, 2021 at 05:16:45PM +0100, Sylvain Pelissier wrote:
> > > On Thu, 28 Jan 2021 at 18:17, Sylvain Pelissier
> > > <sylvain.pelissier@gmail.com> wrote:
> > > >
> > > > On Thu, 28 Jan 2021 at 09:22, Greg KH <gregkh@linuxfoundation.org>
> > wrote:
> > > > >
> > > > > On Thu, Jan 28, 2021 at 09:12:59AM +0100, Sylvain Pelissier wrote:
> > > > > > The macros defining structures for descriptors use token
> > > > > > pasting incorrectly. For example, the macro
> > > > > > UVC_EXTENSION_UNIT_DESCRIPTOR(1, 2) defines a structure named
> > > > > > uvc_extension_unit_descriptor_p_2 which should be
> > > > > > uvc_extension_unit_descriptor_1_2 instead.
> > > > > >
> > > > > > Signed-off-by: Sylvain Pelissier <sylvain.pelissier@gmail.com>
> > > > > > ---
> > > > > >  include/uapi/linux/usb/video.h | 6 +++---
> > > > > >  1 file changed, 3 insertions(+), 3 deletions(-)
> > > > > >
> > > > > > diff --git a/include/uapi/linux/usb/video.h
> > b/include/uapi/linux/usb/video.h
> > > > > > index d854cb19c42c..1eb982df87a0 100644
> > > > > > --- a/include/uapi/linux/usb/video.h
> > > > > > +++ b/include/uapi/linux/usb/video.h
> > > > > > @@ -324,7 +324,7 @@ struct uvc_extension_unit_descriptor {
> > > > > >  #define UVC_DT_EXTENSION_UNIT_SIZE(p, n)             (24+(p)+(n))
> > > > > >
> > > > > >  #define UVC_EXTENSION_UNIT_DESCRIPTOR(p, n) \
> > > > > > -     uvc_extension_unit_descriptor_##p_##n
> > > > > > +     uvc_extension_unit_descriptor_##p##_##n
> > > > > >
> > > > > >  #define DECLARE_UVC_EXTENSION_UNIT_DESCRIPTOR(p, n)  \
> > > > > >  struct UVC_EXTENSION_UNIT_DESCRIPTOR(p, n) {         \
> > > > > > @@ -371,7 +371,7 @@ struct uvc_input_header_descriptor {
> > > > > >  #define UVC_DT_INPUT_HEADER_SIZE(n, p)
> >  (13+(n*p))
> > > > > >
> > > > > >  #define UVC_INPUT_HEADER_DESCRIPTOR(n, p) \
> > > > > > -     uvc_input_header_descriptor_##n_##p
> > > > > > +     uvc_input_header_descriptor_##n##_##p
> > > > > >
> > > > > >  #define DECLARE_UVC_INPUT_HEADER_DESCRIPTOR(n, p)    \
> > > > > >  struct UVC_INPUT_HEADER_DESCRIPTOR(n, p) {           \
> > > > > > @@ -406,7 +406,7 @@ struct uvc_output_header_descriptor {
> > > > > >  #define UVC_DT_OUTPUT_HEADER_SIZE(n, p)
> > (9+(n*p))
> > > > > >
> > > > > >  #define UVC_OUTPUT_HEADER_DESCRIPTOR(n, p) \
> > > > > > -     uvc_output_header_descriptor_##n_##p
> > > > > > +     uvc_output_header_descriptor_##n##_##p
> > > > > >
> > > > > >  #define DECLARE_UVC_OUTPUT_HEADER_DESCRIPTOR(n, p)   \
> > > > > >  struct UVC_OUTPUT_HEADER_DESCRIPTOR(n, p) {          \
> > > > > > --
> > > > > > 2.25.1
> > > > > >
> > > > >
> > > > > And no one noticed this?  If not, then why do we have these defines
> > at
> > > > > all, as obviously they are not used :)
> > > >
> > > > The problem is not detected if you have descriptors with the second
> > > > argument different each time since the structure name will change. It
> > > > is maybe why it was not noticed. Nevertheless, the extension unit, the
> > > > input header and the output header descriptors are part of the USB
> > > > video class specification and are often used by devices. We have
> > > > detected the problem while implementing a usb gadget having such
> > > > descriptors.
> > > >
> > > Hi,
> > > Do I need to change something for this patch ?
> >
> > I need an ack from the v4l maintainers before I can take it...
> >
> 
> Do I need to add someone in cc in particular?

I think Laurent is the proper one here as he's the maintainer for the
usb v4l driver, right?

thanks,

greg k-h