Re: [ofa-general] Re: [PATCH v4 14/14] QLogic VNIC: sysfs Documentation

Amar Mudrankit wrote:

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I was looking at latest release of iproute2, in which I could not
locate fill_xstats. Can you help me to locate this?

->fill_xstats is in the kernel, in iproute its ->print_xstats.

I was looking at kernel code net/8021q/vlan_netlink.c on which I have
following queries:

a.  Is it a correct file in kernel I m referring to?

Yes.

b.  vlan_fill_info is a function to send parameters back to user
level. What is the role of skb as an argument to function? Is some
network operation expected?

netlink is a (local) networking protocol, this is the message
sent to userspace.

c.  How exactly the kernel API ops->get_size comes into play? I guess
user prog should first get the size of parameters that will be
returned by driver before calling ops->fill_info.

No, its used internally for skb allocation. It should return
the size of all encapsulated netlink attributes that will be
dumped by ->fill_info (in most cases, just a constant value).

d.  Can somebody briefly introduce struct nlattr? It looks like all
parameters flow through this structure.

Not much to say about it, nla_type contains the numerical
attribute type, nla_len the length without padding. Data
follows the attribute, followed by padding to a multiple
of four. The netlink construction functions and macros
from include/net/netlink.h take care of all of this for
you.