Re: [RFC 3/4] wwan: add interface creation support

Hi Sergey,

Wow, this is a perfect solution! I just could not help but praise this
proposal :)

Heh.

When researching the latest WWAN device drivers and related
discussions, I began to assume that implementing the netdev management
API without the dummy (no-op) netdev is only possible using genetlink.
But this usage of a regular device specified by its name as a parent
for netdev creation is so natural and clear that I believe in RTNL
again.

Let me place my 2 cents. Maybe the parent device attribute should be
made generic? E.g. call it IFLA_PARENT_DEV_NAME, with usage semantics
similar to the IFLA_LINK attribute for VLAN interfaces. The case when
a user needs to create a netdev on behalf of a regular device is not
WWAN specific, IMHO. So, other drivers could benefit from such
attribute too. To be honest, I can not recall any driver that could
immediately start using such attribute, but the situation with the
need for such attribute seems to be quite common.

That's a good question/thought.

I mean, in principle this is trivial, right? Just add a
IFLA_PARENT_DEV_NAME like you say, and use it instead of
IFLA_WWAN_DEV_NAME.

It'd come out of tb[] instead of data[] and in this case would remove
the need to add the additional data[] argument to rtnl_create_link() in
my patch, since it's in tb[] then.

The only thing I'd be worried about is that different implementations
use it for different meanings, but I guess that's not that big a deal?

johannes