Re: VIRTIO_NET_HDR_F_RSC_INFO in virtio-net vs headers update

[Cornelia Huck <cohuck@redhat.com>]

On Mon, 27 Apr 2020 16:41:30 +0800
Jason Wang <jasowang@redhat.com> wrote:

> 
> On 2020/4/27 下午3:33, Cornelia Huck wrote:
> > Hi,
> >
> > I'm currently trying to prepare a linux-headers update to 5.7-rc3,
> > which adds the definition of VIRTIO_NET_HDR_F_RSC_INFO.
> >
> > Unfortunately, this breaks the build of virtio-net, because now
> > virtio_net_rsc_ext_num_{packets,dupacks} are undefined (they are
> > guarded by existence of VIRTIO_NET_HDR_F_RSC_INFO).
> >
> > What is the right way to fix this? Remove the constants that are now
> > provided by the header and keep the definitions of
> > virtio_net_rsc_ext_num_{packets,dupacks}?
> 
> 
> We probably need to add a version of the above function when 
> VIRTIO_NET_HDR_F_RSC_INFO is defined as attached.
> 
> But I fail to understand why we need a fallback when 
> VIRTIO_NET_HDR_F_RSC_INFO is not defined.

Yes, the current code in virtio-net looks a bit odd, which is why I
asked.

I see two options:
- do the change you proposed, do the headers update, and then rip out
   the compat handling
- do the above in a single step

I'd prefer the second option.

> 
> Thanks
> 
> 
> >
> > [I'd like to queue a headers update as soon as possible, as the whole
> > s390 protected virt stuff depends on it...]
> >
> >