Re: [RFC v2 -next 2/2] virtio_net: Read the advised MTU

Sergei Shtylyov [off-list ref] writes:

Hello.

On 3/16/2016 12:04 AM, 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 <redacted>
---
v2:
* Whitespace cleanup in the last hunk
* Code style change around the pr_warn
* Additional test for mtu change before printing warning

  drivers/net/virtio_net.c | 12 ++++++++++++
  1 file changed, 12 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 767ab11..429fe01 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

[...]

quoted

@@ -1390,8 +1391,11 @@ 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) && (dev->mtu != new_mtu))

   Inner parens not needed, please be consistent with the code above.

Okay, I will do that.

Thanks so much for the review (again), Sergei!

-Aaron

[...]

MBR, Sergei