RE: [virtio-comment] Re: [PATCH v2 1/2] virtio-net: Fix receive buffer size calculation text

[Parav Pandit <parav@nvidia.com>]

> From: virtio-comment@lists.oasis-open.org <virtio-comment@lists.oasis-
> open.org> On Behalf Of Parav Pandit
> Sent: Monday, February 5, 2024 9:54 PM
> To: Cornelia Huck <cohuck@redhat.com>; Michael S. Tsirkin
> <mst@redhat.com>
> Cc: virtio-comment@lists.oasis-open.org; Shahaf Shuler
> <shahafs@nvidia.com>; xuanzhuo@linux.alibaba.com;
> yuri.benditovich@daynix.com
> Subject: RE: [virtio-comment] Re: [PATCH v2 1/2] virtio-net: Fix receive buffer
> size calculation text
> 
> 
> 
> > From: Cornelia Huck <cohuck@redhat.com>
> > Sent: Monday, February 5, 2024 8:50 PM
> >
> > On Tue, Jan 16 2024, "Michael S. Tsirkin" <mst@redhat.com> wrote:
> >
> > > On Tue, Jan 16, 2024 at 01:18:59PM +0000, Parav Pandit wrote:
> > >>
> > >> > From: Cornelia Huck <cohuck@redhat.com>
> > >> > Sent: Tuesday, January 16, 2024 6:08 PM
> > >> > To: Parav Pandit <parav@nvidia.com>;
> > >> > virtio-comment@lists.oasis-open.org;
> > >> > mst@redhat.com
> > >> > Cc: Shahaf Shuler <shahafs@nvidia.com>;
> > >> > xuanzhuo@linux.alibaba.com; yuri.benditovich@daynix.com
> > >> > Subject: RE: [PATCH v2 1/2] virtio-net: Fix receive buffer size
> > >> > calculation text
> > >> >
> > >> > On Tue, Jan 16 2024, Parav Pandit <parav@nvidia.com> wrote:
> > >> >
> > >> > >> From: Cornelia Huck <cohuck@redhat.com>
> > >> > >> Sent: Tuesday, January 16, 2024 4:33 PM
> > >> > >> To: Parav Pandit <parav@nvidia.com>;
> > >> > >> virtio-comment@lists.oasis-open.org;
> > >> > >> mst@redhat.com
> > >> > >> Cc: Shahaf Shuler <shahafs@nvidia.com>;
> > >> > >> xuanzhuo@linux.alibaba.com; yuri.benditovich@daynix.com
> > >> > >> Subject: RE: [PATCH v2 1/2] virtio-net: Fix receive buffer
> > >> > >> size calculation text
> > >> > >>
> > >> > >> On Tue, Jan 16 2024, Parav Pandit <parav@nvidia.com> wrote:
> > >> > >>
> > >> > >> >> From: Cornelia Huck <cohuck@redhat.com>
> > >> > >> >> Sent: Monday, January 15, 2024 10:14 PM
> > >> > >> >
> > >> > >> >> On Mon, Jan 15 2024, Parav Pandit <parav@nvidia.com> wrote:
> > >> > >> >> > +The driver MUST consider size of field \field{struct
> > >> > >> >> > +virtio_net_hdr}
> > >> > >> >> > +20 bytes if VIRTIO_NET_F_HASH_REPORT is negotiated, and
> > >> > >> >> > +12 bytes if
> > >> > >> >> not.
> > >> > >> >> > +
> > >> > >> >>
> > >> > >> >> Requiring the driver to consider the size of something to
> > >> > >> >> be its actual size seems a bit odd :) I don't think we need
> > >> > >> >> this, as the
> >
> > My comment here still holds.
> >
> It is a variable length data structure with few trailing fields as not valid.
> The "actual size" depends on negotiated feature bit, which is what is written
> here.
> 
> How about below?
> 
> When calculating the size of \field{struct virtio_net_hdr}, the driver must
> consider all the fields inclusive up to \field{padding_reserved}, i.e. 20 bytes if
> VIRTIO_NET_F_HASH_REPORT is negotiated, and 12 bytes if not.

I will shortly post v4 with this as there is no objection for this one line change.
Thanks.