Re: [PATCH v3] media: add virtio-media driver

[Alexandre Courbot <gnurou@gmail.com>]

Hi Mauro,

On Fri, Jul 25, 2025 at 2:24 AM Mauro Carvalho Chehab
<mchehab+huawei@kernel.org> wrote:
>
> Em Sun, 1 Jun 2025 12:01:22 +0200
> Ricardo Ribalda <ribalda@chromium.org> escreveu:
>
> > Hi Mauro
> >
> > On Sun, 1 Jun 2025 at 11:34, Mauro Carvalho Chehab
> > <mchehab+huawei@kernel.org> wrote:
> > >
> > > Em Wed, 28 May 2025 18:23:02 +0200
> > > Ricardo Ribalda <ribalda@chromium.org> escreveu:
> > >
> > > > > +static int scatterlist_builder_add_userptr(struct scatterlist_builder *builder,
> > > > > +                                          unsigned long userptr,
> > > > > +                                          unsigned long length)
> > > > > +{
> > > > > +       int ret;
> > > > > +       int nents;
> > > > Could you initialize nents and sg_list?
> > > > old versions of gcc are a bit picky
> > > > https://gitlab.freedesktop.org/linux-media/users/ribalda/-/jobs/77042562#L4381
> > >
> > > Please don't. In this specific case, ret is always initialized:
> > >
> > > > +       struct virtio_media_sg_entry *sg_list;
> > > > +
> > > > +       ret = __scatterlist_builder_add_userptr(builder, userptr, length,
> > > > +                                               &sg_list, &nents);
> > >
> > > nents and sg_list may or may not be initialized at the function,
> > > but initializing it is wrong, as, when they are not initialized, the
> > > ret code shall catch it (and if not, we *do* want gcc to warn).
> > >
> > > So, if our CI is warning about that due to an old version, please upgrade
> > > the version at the CI runner.
> >
> > The main version of gcc works fine. It is the minimal version (8.1) required by
> > https://www.kernel.org/doc/html/next/process/changes.html
> > that  complains.
>
> Ricardo,
>
> gcc 8.1 was released in May 2, 2018. I don't think it makes sense to
> address bogus warnings with that old gcc versions. I would just disable
> WERROR for such versions on our CI tests.
>
> ---
>
> Alexandre/Michael,
>
> I need a couple of full days to properly review virtio-media.
> I was planning to do it during this Kernel cycle, but I ended
> allocating too much time just to be able to create a crossvm
> that would allow testing it. Afterwards, I got sidetracked with other
> issues. I won't be able to review it in time for this merge window.
>
> I'm planning to do it at the beginning of the next merge cycle.

Not a worry at all and I appreciate the time you are putting aside to
review this properly!

Thanks,
Alex.