virtio-net: Update the mtu code to match virtio spec

The virtio committee recently ratified a change, VIRTIO-152, which
defines the mtu field to be 'max' MTU, not simply desired MTU.

This commit brings the virtio-net device in compliance with VIRTIO-152.

Additionally, drop the max_mtu branch - it cannot be taken since the u16
returned by virtio_cread16 will never exceed the initial value of
max_mtu.

Signed-off-by: Aaron Conole <aconole@redhat.com>
Acked-by: "Michael S. Tsirkin" <mst@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 720809f82a0e60aeb7c3f894d74eb2ba8eb90614..2cafd12a10752e1e02c28c5ee0a8594ac76833a0 100644 (file)
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c
@@ -1870,10 +1870,12 @@ static int virtnet_probe(struct virtio_device *vdev)
                mtu = virtio_cread16(vdev,
                                     offsetof(struct virtio_net_config,
                                              mtu));
-               if (mtu < dev->min_mtu || mtu > dev->max_mtu)
+               if (mtu < dev->min_mtu) {
                        __virtio_clear_bit(vdev, VIRTIO_NET_F_MTU);
-               else
+               } else {
                        dev->mtu = mtu;
+                       dev->max_mtu = mtu;
+               }
        }
 
        if (vi->any_header_sg)