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

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Date:	Tue, 2 Feb 2016 15:59:52 +0100
From:	Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
To:	"Michael S. Tsirkin" <mst@...hat.com>,
	Nikolay Aleksandrov <razor@...ckwall.org>
Cc:	netdev@...r.kernel.org, roopa@...ulusnetworks.com,
	davem@...emloft.net
Subject: Re: [PATCH net-next v2 2/2] virtio_net: add ethtool support for set
 and get of settings

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@...ulusnetworks.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@...ulusnetworks.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 ?

>> +	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