Re: [RFC -next 2/2] virtio_net: Read and use the advised MTU

Sergei Shtylyov [off-list ref] writes:

Hello.

Hi Sergei,

On 03/10/2016 05:28 PM, Aaron Conole wrote:

quoted

This patch checks the feature bit for the VIRTIO_NET_F_MTU feature. If it
exists, read the advised MTU and use it.

No proper error handling is provided for the case where a user changes the
negotiated MTU. A future commit will add proper error handling. Instead, a
warning is emitted if the guest changes the device MTU after previously being
given advice.

Signed-off-by: Aaron Conole <aconole@redhat.com>
---
  drivers/net/virtio_net.c | 15 ++++++++++++++-
  1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 767ab11..7175563 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

[...]

quoted

@@ -1390,8 +1391,12 @@ static const struct ethtool_ops virtnet_ethtool_ops = {

  static int virtnet_change_mtu(struct net_device *dev, int new_mtu)
  {
+	struct virtnet_info *vi = netdev_priv(dev);
  	if (new_mtu < MIN_MTU || new_mtu > MAX_MTU)
  		return -EINVAL;
+	if (vi->negotiated_mtu == true) {
+		pr_warn("changing mtu from negotiated mtu.");
+	}

   {} not needed, see Documentation/CodingStyle.

Okay, I'll make sure to fix this with v2.

[...]

MBR, Sergei

Thanks so much for the review!

-Aaron