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Date: Thu, 24 Jun 2010 11:39:14 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
Message-ID: <20100624083914.GC937@redhat.com>
References: <20100623095118.GA9796@redhat.com>
	<20100624084213.GQ27193@amit-laptop.redhat.com>
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Subject: [Qemu-devel] Re: [PATCH] virtio-net: correct header length math
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To: Amit Shah <amit.shah@redhat.com>
Cc: alex.williamson@redhat.com, qemu-devel@nongnu.org, Juan Quintela <quintela@redhat.com>

On Thu, Jun 24, 2010 at 02:12:13PM +0530, Amit Shah wrote:
> On (Wed) Jun 23 2010 [12:51:18], Michael S. Tsirkin wrote:
> > We were requesting too much when checking buffer
> > length: size already includes host header length.
> > 
> > Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
> > ---
> >  hw/virtio-net.c |   20 +++++++++++---------
> >  1 files changed, 11 insertions(+), 9 deletions(-)
> 
> Couple of minor comments. But I'll still provide the
> 
> ACK
> 
> > @@ -556,9 +557,10 @@ static ssize_t virtio_net_receive(VLANClientState *nc, const uint8_t *buf, size_
> >              virtqueue_pop(n->rx_vq, &elem) == 0) {
> >              if (i == 0)
> >                  return -1;
> > -            fprintf(stderr, "virtio-net truncating packet: "
> > -                    "offset %zd, size %zd, hdr_len %zd\n",
> > -                    offset, size, hdr_len);
> > +            fprintf(stderr, "virtio-net truncating packet: i %d mergeable %d "
> > +                    "offset %zd, size %zd, guest hdr %zd, host hdr %zd\n",
> > +		    i, n->mergeable_rx_bufs,
> > +                    offset, size, guest_hdr_len, host_hdr_len);
> 
> Again, tab usage and 'guest hdr len' and 'host hdr len' make better
> sense than 'guest hdr' and 'host hdr'
> 
> >              exit(1);
> 
> Can we drop the packet(s) instead of exiting?
> 
> 		Amit

This is a guest bug in the same way as moving indexes incorrectly.
But since we do have such buggy guests in the field (old virtio),
I guess we should.

-- 
MST