Subject: Re: [RFC 2/2] net: Add support for NTB virtual ethernet device

From: Jon Mason <[email-masked]>
Date: Fri, 13 Jul 2012 22:55:09 -0700

On Fri, Jul 13, 2012 at 05:08:26PM -0700, Stephen Hemminger wrote:
> On Fri, 13 Jul 2012 14:45:00 -0700
> Jon Mason <[email-masked]> wrote:
> 
> > A virtual ethernet device that uses the NTB transport API to send/receive data.
> > 
> > Signed-off-by: Jon Mason <[email-masked]>
> > ---
> >  drivers/net/Kconfig      |    4 +
> >  drivers/net/Makefile     |    1 +
> >  drivers/net/ntb_netdev.c |  411 ++++++++++++++++++++++++++++++++++++++++++++++
> >  3 files changed, 416 insertions(+), 0 deletions(-)
> >  create mode 100644 drivers/net/ntb_netdev.c
> 
> 
> > +static void ntb_get_drvinfo(__attribute__((unused)) struct net_device *dev,
> > +			    struct ethtool_drvinfo *info)
> > +{
> > +	strlcpy(info->driver, KBUILD_MODNAME, sizeof(info->driver));
> > +	strlcpy(info->version, NTB_NETDEV_VER, sizeof(info->version));
> > +}
> > +
> > +static const char ntb_nic_stats[][ETH_GSTRING_LEN] = {
> > +	"rx_packets", "rx_bytes", "rx_errors", "rx_dropped", "rx_length_errors",
> > +	"rx_frame_errors", "rx_fifo_errors",
> > +	"tx_packets", "tx_bytes", "tx_errors", "tx_dropped",
> > +};
> > +
> > +static int ntb_get_stats_count(__attribute__((unused)) struct net_device *dev)
> > +{
> > +	return ARRAY_SIZE(ntb_nic_stats);
> > +}
> > +
> > +static int ntb_get_sset_count(struct net_device *dev, int sset)
> > +{
> > +	switch (sset) {
> > +	case ETH_SS_STATS:
> > +		return ntb_get_stats_count(dev);
> > +	default:
> > +		return -EOPNOTSUPP;
> > +	}
> > +}
> > +
> > +static void ntb_get_strings(__attribute__((unused)) struct net_device *dev,
> > +			    u32 sset, u8 *data)
> > +{
> > +	switch (sset) {
> > +	case ETH_SS_STATS:
> > +		memcpy(data, *ntb_nic_stats, sizeof(ntb_nic_stats));
> > +	}
> > +}
> > +
> > +static void
> > +ntb_get_ethtool_stats(struct net_device *dev,
> > +		      __attribute__((unused)) struct ethtool_stats *stats,
> > +		      u64 *data)
> > +{
> > +	int i = 0;
> > +
> > +	data[i++] = dev->stats.rx_packets;
> > +	data[i++] = dev->stats.rx_bytes;
> > +	data[i++] = dev->stats.rx_errors;
> > +	data[i++] = dev->stats.rx_dropped;
> > +	data[i++] = dev->stats.rx_length_errors;
> > +	data[i++] = dev->stats.rx_frame_errors;
> > +	data[i++] = dev->stats.rx_fifo_errors;
> > +	data[i++] = dev->stats.tx_packets;
> > +	data[i++] = dev->stats.tx_bytes;
> > +	data[i++] = dev->stats.tx_errors;
> > +	data[i++] = dev->stats.tx_dropped;
> > +}
> 
> These statistics add no value over existing network stats.
> Don't implement ethtool stats unless device has something more
> interesting to say.

Fair enough

> 
> > +static const struct ethtool_ops ntb_ethtool_ops = {
> > +	.get_drvinfo = ntb_get_drvinfo,
> > +	.get_sset_count = ntb_get_sset_count,
> > +	.get_strings = ntb_get_strings,
> > +	.get_ethtool_stats = ntb_get_ethtool_stats,
> > +	.get_link = ethtool_op_get_link,
> > +};
> 
> If you want to implement bonding or bridging then implementing
> get_settings would help.

Will do.

> > +static int __init ntb_netdev_init_module(void)
> > +{
> > +	struct ntb_netdev *dev;
> > +	int rc;
> > +
> > +	pr_info("%s: Probe\n", KBUILD_MODNAME);
> 
> Useless message

True, will remove.

Thanks for the comments!
 
> > +	netdev = alloc_etherdev(sizeof(struct ntb_netdev));
> > +	if (!netdev)
> > +		return -ENOMEM;
> > +
> > +	dev = netdev_priv(netdev);
> > +	dev->ndev = netdev;
> > +	netdev->features = NETIF_F_HIGHDMA;
> > +
> > +	netdev->hw_features = netdev->features;
> > +	netdev->watchdog_timeo = msecs_to_jiffies(NTB_TX_TIMEOUT_MS);
> > +
> > +	random_ether_addr(netdev->perm_addr);
> > +	memcpy(netdev->dev_addr, netdev->perm_addr, netdev->addr_len);
> > +
> > +	netdev->netdev_ops = &ntb_netdev_ops;
> > +	SET_ETHTOOL_OPS(netdev, &ntb_ethtool_ops);
> > +
> > +	dev->qp = ntb_transport_create_queue(ntb_netdev_rx_handler,
> > +					     ntb_netdev_tx_handler,
> > +					     ntb_netdev_event_handler);
> > +	if (!dev->qp) {
> > +		rc = -EIO;
> > +		goto err;
> > +	}
> > +
> > +	netdev->mtu = ntb_transport_max_size(dev->qp) - ETH_HLEN;
> > +
> > +	rc = register_netdev(netdev);
> > +	if (rc)
> > +		goto err1;
> > +
> > +	pr_info("%s: %s created\n", KBUILD_MODNAME, netdev->name);
> > +	return 0;
> > +
> > +err1:
> > +	ntb_transport_free_queue(dev->qp);
> > +err:
> > +	free_netdev(netdev);
> > +	return rc;
> > +}
> > +module_init(ntb_netdev_init_module);
> > +
> > +static void __exit ntb_netdev_exit_module(void)
> > +{
> > +	struct ntb_netdev *dev = netdev_priv(netdev);
> > +
> > +	unregister_netdev(netdev);
> > +	ntb_transport_free_queue(dev->qp);
> > +	free_netdev(netdev);
> > +
> > +	pr_info("%s: Driver removed\n", KBUILD_MODNAME);
> > +}
> > +module_exit(ntb_netdev_exit_module);
>