Re: [RFC PATCH] net: Add support for virtual machine device queues (VMDQ)

On 7/18/2012 11:42 PM, Jiri Pirko wrote:

Thu, Jul 19, 2012 at 12:05:44AM CEST, john.r.fastabend@intel.com wrote:

quoted

This adds support to allow virtual net devices to be created. These
devices can be managed independtly of the physical function but
use the same physical link.

[...]

quoted

+
+size_t vmdq_getpriv_size(struct net *src_net, struct nlattr *tb[])
+{
+	struct net_device *lowerdev;
+
+	if (!tb[IFLA_LINK])
+		return -EINVAL;
+
+	lowerdev = __dev_get_by_index(src_net, nla_get_u32(tb[IFLA_LINK]));
+	if (!lowerdev)
+		return -ENODEV;
+
+	return sizeof(netdev_priv(lowerdev));
+}

Why exactly do you need to have the priv of same size as lowerdev? I do
not see you use that anywhere...

When we add a child device the hardware/sw may have some private data
it needs to manage this device.

I made an assumption here that the priv space for child devices is the
same as the lowerdev but this might be a bad assumption.

.John