On Wed, Jan 18, 2017 at 11:54:21AM +0800, Jason Wang wrote:
>
>
> On 2017年01月18日 02:27, Michael S. Tsirkin wrote:
> > On Tue, Jan 17, 2017 at 06:13:51PM +0000, Rolf Neugebauer wrote:
> > > This patch part reverts fd2a0437dc33 and e858fae2b0b8 which introduced a
> > > subtle change in how the virtio_net flags are derived from the SKBs
> > > ip_summed field.
> > >
> > > With the above commits, the flags are set to VIRTIO_NET_HDR_F_DATA_VALID
> > > when ip_summed == CHECKSUM_UNNECESSARY, thus treating it differently to
> > > ip_summed == CHECKSUM_NONE, which should be the same.
> > >
> > > Further, the virtio spec 1.0 / CS04 explicitly says that
> > > VIRTIO_NET_HDR_F_DATA_VALID must not be set by the driver.
> > >
> > > Signed-off-by: Rolf Neugebauer <rolf.neugeba...@docker.com>
> > Fixes: fd2a0437dc33 ("virtio_net: introduce virtio_net_hdr_{from,to}_skb")
> > Fixes: e858fae2b0b8 (" virtio_net: use common code for virtio_net_hdr and
> > skb GSO conversion")
> > Acked-by: Michael S. Tsirkin <m...@redhat.com>
> >
> > Should be backported into stable as well.
>
> Looks like a side effect is that we will never see this on receive path?
I thought receive path is using virtio_net_hdr_to_skb - isn't it?
> We
> probably need a hint for virtio_net_hdr_from_skb().
>
> Thanks
>
> >
> >
> > > ---
> > > include/linux/virtio_net.h | 2 --
> > > 1 file changed, 2 deletions(-)
> > >
> > > diff --git a/include/linux/virtio_net.h b/include/linux/virtio_net.h
> > > index 66204007d7ac..56436472ccc7 100644
> > > --- a/include/linux/virtio_net.h
> > > +++ b/include/linux/virtio_net.h
> > > @@ -91,8 +91,6 @@ static inline int virtio_net_hdr_from_skb(const struct
> > > sk_buff *skb,
> > > skb_checksum_start_offset(skb));
> > > hdr->csum_offset = __cpu_to_virtio16(little_endian,
> > > skb->csum_offset);
> > > - } else if (skb->ip_summed == CHECKSUM_UNNECESSARY) {
> > > - hdr->flags = VIRTIO_NET_HDR_F_DATA_VALID;
> > > } /* else everything is zero */
> > > return 0;
> > > --
> > > 2.11.0
