Re: [PATCH net-next v2 2/2] virtio_net: add ethtool support for set and get of settings

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Feb 02, 2016 at 03:59:52PM +0100, Nikolay Aleksandrov wrote:
> On 02/02/2016 03:54 PM, Michael S. Tsirkin wrote:
> > On Tue, Feb 02, 2016 at 03:33:40PM +0100, Nikolay Aleksandrov wrote:
> >> From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
> >>
> >> This patch allows the user to set and retrieve speed and duplex of the
> >> virtio_net device via ethtool. Having this functionality is very helpful
> >> for simulating different environments and also enables the virtio_net
> >> device to participate in operations where proper speed and duplex are
> >> required (e.g. currently bonding lacp mode requires full duplex). Custom
> >> speed and duplex are not allowed, the user-supplied settings are validated
> >> before applying.
> >>
> >> Example:
> >> $ ethtool eth1
> >> Settings for eth1:
> >> ...
> >> 	Speed: Unknown!
> >> 	Duplex: Unknown! (255)
> >> $ ethtool -s eth1 speed 1000 duplex full
> >> $ ethtool eth1
> >> Settings for eth1:
> >> ...
> >> 	Speed: 1000Mb/s
> >> 	Duplex: Full
> >>
> >> Based on a patch by Roopa Prabhu.
> >>
> >> Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
> >> ---
> >> v2: use the new ethtool speed/duplex validation functions and allow half
> >> duplex to be set
> >>
> >>  drivers/net/virtio_net.c | 41 +++++++++++++++++++++++++++++++++++++++++
> >>  1 file changed, 41 insertions(+)
> >>
> >> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> >> index 767ab11a6e9f..88fdb162c5f5 100644
> >> --- a/drivers/net/virtio_net.c
> >> +++ b/drivers/net/virtio_net.c
> >> @@ -146,6 +146,10 @@ struct virtnet_info {
> >>  	virtio_net_ctrl_ack ctrl_status;
> >>  	u8 ctrl_promisc;
> >>  	u8 ctrl_allmulti;
> >> +
> >> +	/* Ethtool settings */
> >> +	u8 duplex;
> >> +	u32 speed;
> >>  };
> >>  
> >>  struct padded_vnet_hdr {
> >> @@ -1376,6 +1380,39 @@ static void virtnet_get_channels(struct net_device *dev,
> >>  	channels->other_count = 0;
> >>  }
> >>  
> >> +static int virtnet_set_settings(struct net_device *dev, struct ethtool_cmd *cmd)
> >> +{
> >> +	struct virtnet_info *vi = netdev_priv(dev);
> > 
> > need an empty line here.
> > 
> 
> The next line is a local variable declaration, you want a new line between
> the two local variable declarations ?

Oh, you are right.

> >> +	u32 speed = ethtool_cmd_speed(cmd);
> >> +
> >> +	/* don't allow custom speed and duplex */
> >> +	if (!ethtool_validate_speed(speed) ||
> >> +	    !ethtool_validate_duplex(cmd->duplex))
> >> +		return -EINVAL;
> > 
> > There's a problem here: rest of the fields are ignored.
> > Here's one way to validate user doesn't attempt to set them:
> > 
> 
> Hmm, yes, they'll silently get ignored without an error. Good point,
> and I'll modify as necessary.
> 
> Thanks!
> 
> > 	struct ethtool_cmd diff1 = cmd;
> > 	struct ethtool_cmd diff2 = {};
> > 
> > 	ethtool_cmd_speed_set(&diff1, 0);
> > 	diff1.duplex = 0;
> > 
> > 	if (memcmp(&diff1, &diff2, sizeof diff1))
> > 		return -EINVAL;
> > 
> > 
> >> +	vi->speed = speed;
> >> +	vi->duplex = cmd->duplex;
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static int virtnet_get_settings(struct net_device *dev, struct ethtool_cmd *cmd)
> >> +{
> >> +	struct virtnet_info *vi = netdev_priv(dev);
> >> +
> >> +	ethtool_cmd_speed_set(cmd, vi->speed);
> >> +	cmd->duplex = vi->duplex;
> > 
> > 
> > I think we should at least set port to PORT_OTHER.
> > 
> >> +
> >> +	return 0;
> >> +}
> >> +
> >> +static void virtnet_init_settings(struct net_device *dev)
> >> +{
> >> +	struct virtnet_info *vi = netdev_priv(dev);
> >> +
> >> +	vi->speed = SPEED_UNKNOWN;
> >> +	vi->duplex = DUPLEX_UNKNOWN;
> >> +}
> >> +
> >>  static const struct ethtool_ops virtnet_ethtool_ops = {
> >>  	.get_drvinfo = virtnet_get_drvinfo,
> >>  	.get_link = ethtool_op_get_link,
> >> @@ -1383,6 +1420,8 @@ static const struct ethtool_ops virtnet_ethtool_ops = {
> >>  	.set_channels = virtnet_set_channels,
> >>  	.get_channels = virtnet_get_channels,
> >>  	.get_ts_info = ethtool_op_get_ts_info,
> >> +	.get_settings = virtnet_get_settings,
> >> +	.set_settings = virtnet_set_settings,
> >>  };
> >>  
> >>  #define MIN_MTU 68
> >> @@ -1855,6 +1894,8 @@ static int virtnet_probe(struct virtio_device *vdev)
> >>  	netif_set_real_num_tx_queues(dev, vi->curr_queue_pairs);
> >>  	netif_set_real_num_rx_queues(dev, vi->curr_queue_pairs);
> >>  
> >> +	virtnet_init_settings(dev);
> >> +
> >>  	err = register_netdev(dev);
> >>  	if (err) {
> >>  		pr_debug("virtio_net: registering device failed\n");
> >> -- 
> >> 2.4.3