Messages in this thread | | | Date | Thu, 25 Nov 2021 09:09:39 +0200 | From | Eli Cohen <> | Subject | Re: [PATCH net] virtio-net: enable big mode correctly |
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On Thu, Nov 25, 2021 at 02:05:47PM +0800, Jason Wang wrote: > When VIRTIO_NET_F_MTU feature is not negotiated, we assume a very > large max_mtu. In this case, using small packet mode is not correct > since it may breaks the networking when MTU is grater than > ETH_DATA_LEN. > > To have a quick fix, simply enable the big packet mode when > VIRTIO_NET_F_MTU is not negotiated. We can do optimization on top. > > Reported-by: Eli Cohen <elic@nvidia.com> > Cc: Eli Cohen <elic@nvidia.com> > Signed-off-by: Jason Wang <jasowang@redhat.com> > --- > drivers/net/virtio_net.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > index 7c43bfc1ce44..83ae3ef5eb11 100644 > --- a/drivers/net/virtio_net.c > +++ b/drivers/net/virtio_net.c > @@ -3200,11 +3200,12 @@ static int virtnet_probe(struct virtio_device *vdev) > dev->mtu = mtu; > dev->max_mtu = mtu; > > - /* TODO: size buffers correctly in this case. */ > - if (dev->mtu > ETH_DATA_LEN) > - vi->big_packets = true; > } > > + /* TODO: size buffers correctly in this case. */ > + if (dev->max_mtu > ETH_DATA_LEN) > + vi->big_packets = true; > +
If VIRTIO_NET_F_MTU is provided, then dev->max_mtu is going to equal ETH_DATA_LEN (will be set in ether_setup()) so I don't think it will set big_packets to true.
> if (vi->any_header_sg) > dev->needed_headroom = vi->hdr_len; > > -- > 2.25.1 >
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