Re: [RFC -next 2/2] virtio_net: Read and use the advised MTU
From: Paolo Abeni <pabeni@redhat.com>
Date: 2016-03-10 14:57:33
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On Thu, 2016-03-10 at 09:28 -0500, Aaron Conole wrote:
quoted hunk ↗ jump to hunk
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@@ -146,6 +146,7 @@ struct virtnet_info { virtio_net_ctrl_ack ctrl_status; u8 ctrl_promisc; u8 ctrl_allmulti; + bool negotiated_mtu; }; struct padded_vnet_hdr {@@ -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) {
why don't: if ((vi->negotiated_mtu == true) && (dev->mtu != new_mtu)) ?
quoted hunk ↗ jump to hunk
+ pr_warn("changing mtu from negotiated mtu."); + } dev->mtu = new_mtu; return 0; }@@ -1836,6 +1841,13 @@ static int virtnet_probe(struct virtio_device *vdev) if (virtio_has_feature(vdev, VIRTIO_NET_F_CTRL_VQ)) vi->has_cvq = true; + if (virtio_has_feature(vdev, VIRTIO_NET_F_MTU)) { + vi->negotiated_mtu = true; + dev->mtu = virtio_cread16(vdev, + offsetof(struct virtio_net_config, + mtu)); + } + if (vi->any_header_sg) dev->needed_headroom = vi->hdr_len;@@ -2017,8 +2029,9 @@ static unsigned int features[] = { VIRTIO_NET_F_MRG_RXBUF, VIRTIO_NET_F_STATUS, VIRTIO_NET_F_CTRL_VQ, VIRTIO_NET_F_CTRL_RX, VIRTIO_NET_F_CTRL_VLAN, VIRTIO_NET_F_GUEST_ANNOUNCE, VIRTIO_NET_F_MQ, - VIRTIO_NET_F_CTRL_MAC_ADDR, + VIRTIO_NET_F_CTRL_MAC_ADDR,
Here a trailing white space slipped-in. Otherwise LGTM. Paolo
VIRTIO_F_ANY_LAYOUT,
+ VIRTIO_NET_F_MTU,
};
static struct virtio_driver virtio_net_driver = {