How to configure udev to rename USB network cards correctly

[Steffen Dettmer <steffen.dettmer@gmail.com>]

Hi,

we have USB network cards and udev rules for them, for example:

SUBSYSTEM=="net", ACTION=="add", ATTRS{manufacturer}=="Novatel
Wireless*", ATTRS{serial}=="?*", NAME="ethnovatel%n"

when booting, we see e.g., "ethnovatel3" and "ethnovatel4", as expected.

When unplugging/replugging (or power cycling) the USB devices, it
often happens that one devices is called "rename22" (with an
arbitrary, increasing number). My guess is that this happens because
%n is unfortunately not a unique counter but the number of the device
befor renaming it, and that it happens that first device gets kernel
name "eth4", is renamed to "ethnovatel4", second device gets "eth4"
from kernel (no conflict") and cannot be renamed to "ethnovatel4",
because already existing.

I looked to udev scripts, which seem to be quite complicated and
difficult to write and debug, so I assume it is not intended to change
them.

How to configure udev to rename USB network cards correctly?

Regards,
Steffen