[NET]: Fix hotplug race during device registration.

[NET]: Fix hotplug race during device registration.

From: Thomas de Grenier de Latour <degrenier@easyconnect.fr>

On Sun, 9 Apr 2006 21:56:59 +0400,
Sergey Vlasov <vsu@altlinux.ru> wrote:

> However, show_address() does not output anything unless
> dev->reg_state == NETREG_REGISTERED - and this state is set by
> netdev_run_todo() only after netdev_register_sysfs() returns, so in
> the meantime (while netdev_register_sysfs() is busy adding the
> "statistics" attribute group) some process may see an empty "address"
> attribute.

I've tried the attached patch, suggested by Sergey Vlasov on
hotplug-devel@, and as far as i can test it works just fine.

Signed-off-by: David S. Miller <davem@davemloft.net>