Subject: Re: [patch net-next v2 05/10] rocker: introduce rocker switch driver

From: John Fastabend <[email-masked]>
Date: Mon, 10 Nov 2014 14:04:26 -0800

On 11/09/2014 02:51 AM, Jiri Pirko wrote:
> This patch introduces the first driver to benefit from the switchdev
> infrastructure and to implement newly introduced switch ndos. This is a
> driver for emulated switch chip implemented in qemu:
> https://github.com/sfeldma/qemu-rocker/
>
> This patch is a result of joint work with Scott Feldman.
>
> Signed-off-by: Scott Feldman <[email-masked]>
> Signed-off-by: Jiri Pirko <[email-masked]>
> ---
>   MAINTAINERS                          |    7 +
>   drivers/net/ethernet/Kconfig         |    1 +
>   drivers/net/ethernet/Makefile        |    1 +
>   drivers/net/ethernet/rocker/Kconfig  |   27 +
>   drivers/net/ethernet/rocker/Makefile |    5 +
>   drivers/net/ethernet/rocker/rocker.c | 2060 ++++++++++++++++++++++++++++++++++
>   drivers/net/ethernet/rocker/rocker.h |  427 +++++++
>   7 files changed, 2528 insertions(+)
>   create mode 100644 drivers/net/ethernet/rocker/Kconfig
>   create mode 100644 drivers/net/ethernet/rocker/Makefile
>   create mode 100644 drivers/net/ethernet/rocker/rocker.c
>   create mode 100644 drivers/net/ethernet/rocker/rocker.h
>

[...]

> +
> +static netdev_tx_t rocker_port_xmit(struct sk_buff *skb, struct net_device *dev)
> +{
> +	struct rocker_port *rocker_port = netdev_priv(dev);
> +	struct rocker *rocker = rocker_port->rocker;
> +	struct rocker_desc_info *desc_info;
> +	struct rocker_tlv *frags;
> +	int i;
> +	int err;
> +
> +	desc_info = rocker_desc_head_get(&rocker_port->tx_ring);
> +	if (unlikely(!desc_info)) {
> +		if (net_ratelimit())

Could you have a netif_stop_queue() here as well same as below? Not
that optimizing the xmit routine is the interesting part of this patch.
But I guess this is just some strange error path because I see you
check this case below.

> +			netdev_err(dev, "tx ring full when queue awake\n");
> +		return NETDEV_TX_BUSY;
> +	}
> +
> +	rocker_desc_cookie_ptr_set(desc_info, skb);
> +
> +	frags = rocker_tlv_nest_start(desc_info, ROCKER_TLV_TX_FRAGS);
> +	if (!frags)
> +		goto out;
> +	err = rocker_tx_desc_frag_map_put(rocker_port, desc_info,
> +					  skb->data, skb_headlen(skb));
> +	if (err)
> +		goto nest_cancel;
> +	if (skb_shinfo(skb)->nr_frags > ROCKER_TX_FRAGS_MAX)
> +		goto nest_cancel;
> +
> +	for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) {
> +		const skb_frag_t *frag = &skb_shinfo(skb)->frags[i];
> +
> +		err = rocker_tx_desc_frag_map_put(rocker_port, desc_info,
> +						  skb_frag_address(frag),
> +						  skb_frag_size(frag));
> +		if (err)
> +			goto unmap_frags;
> +	}
> +	rocker_tlv_nest_end(desc_info, frags);
> +
> +	rocker_desc_gen_clear(desc_info);
> +	rocker_desc_head_set(rocker, &rocker_port->tx_ring, desc_info);
> +
> +	desc_info = rocker_desc_head_get(&rocker_port->tx_ring);
> +	if (!desc_info)
> +		netif_stop_queue(dev);

I'm not entirely sure I followed the TLV usage here but OK. If it
works...

> +
> +	return NETDEV_TX_OK;
> +
> +unmap_frags:
> +	rocker_tx_desc_frags_unmap(rocker_port, desc_info);
> +nest_cancel:
> +	rocker_tlv_nest_cancel(desc_info, frags);
> +out:
> +	dev_kfree_skb(skb);
> +	return NETDEV_TX_OK;
> +}
> +
> +static int rocker_port_set_mac_address(struct net_device *dev, void *p)
> +{
> +	struct sockaddr *addr = p;
> +	struct rocker_port *rocker_port = netdev_priv(dev);
> +	int err;
> +
> +	if (!is_valid_ether_addr(addr->sa_data))
> +		return -EADDRNOTAVAIL;
> +
> +	err = rocker_cmd_set_port_settings_macaddr(rocker_port, addr->sa_data);
> +	if (err)
> +		return err;
> +	memcpy(dev->dev_addr, addr->sa_data, dev->addr_len);
> +	return 0;
> +}
> +
> +static int rocker_port_sw_parent_id_get(struct net_device *dev,
> +					struct netdev_phys_item_id *psid)
> +{
> +	struct rocker_port *rocker_port = netdev_priv(dev);
> +	struct rocker *rocker = rocker_port->rocker;
> +

hmm looks like you read this out of a magic switch register :) but
my switch doesn't have this magic reg. I suposse the switch MAC address
should work.

> +	psid->id_len = sizeof(rocker->hw.id);
> +	memcpy(&psid->id, &rocker->hw.id, psid->id_len);
> +	return 0;
> +}
> +
> +static const struct net_device_ops rocker_port_netdev_ops = {
> +	.ndo_open			= rocker_port_open,
> +	.ndo_stop			= rocker_port_stop,
> +	.ndo_start_xmit			= rocker_port_xmit,
> +	.ndo_set_mac_address		= rocker_port_set_mac_address,
> +	.ndo_sw_parent_id_get		= rocker_port_sw_parent_id_get,
> +};
> +
> +/********************
> + * ethtool interface
> + ********************/
> +
> +static int rocker_port_get_settings(struct net_device *dev,
> +				    struct ethtool_cmd *ecmd)
> +{
> +	struct rocker_port *rocker_port = netdev_priv(dev);
> +
> +	return rocker_cmd_get_port_settings_ethtool(rocker_port, ecmd);
> +}
> +
> +static int rocker_port_set_settings(struct net_device *dev,
> +				    struct ethtool_cmd *ecmd)
> +{
> +	struct rocker_port *rocker_port = netdev_priv(dev);
> +
> +	return rocker_cmd_set_port_settings_ethtool(rocker_port, ecmd);
> +}
> +
> +static void rocker_port_get_drvinfo(struct net_device *dev,
> +				    struct ethtool_drvinfo *drvinfo)
> +{
> +	strlcpy(drvinfo->driver, rocker_driver_name, sizeof(drvinfo->driver));
> +	strlcpy(drvinfo->version, UTS_RELEASE, sizeof(drvinfo->version));
> +}
> +
> +static const struct ethtool_ops rocker_port_ethtool_ops = {
> +	.get_settings		= rocker_port_get_settings,
> +	.set_settings		= rocker_port_set_settings,
> +	.get_drvinfo		= rocker_port_get_drvinfo,
> +	.get_link		= ethtool_op_get_link,
> +};
> +

[...]

Looks reasonable to me, although I mostly scanned it and looked
over the interface parts. My comments are just observations no
need to change anything for them.

Reviewed-by: John Fastabend <[email-masked]>

-- 
John Fastabend         Intel Corporation