Re: [PATCH] net: avoid assigning ethaddr to wrong devices

[Nikita Yushchenko <nikita.yoush@cogentembedded.com>]

>>> It's PowerPC hardware which on barebox is not probed from devicetree, so
>>> indeed there is no device node.
>>
>> But if no device tree, then
>>   alias = of_find_node_by_alias(of_get_root_node(), eth);
>> should return NULL, and eth_is_stranger() should return false, thus
>> making my patch no-op?
> 
> Ok, you are right. I misread the code. You call of_find_node_by_alias()
> on the internal device tree, not the one the Kernel is started with, so
> indeed eth_is_stranger() should return false.
> 
> Nevertheless I do not like this patch very much as it adds more code to
> a place that is already hard to understand in all of its consequences.
> 
> I would like to explore the route that we assign these dynamic devices
> an id that is not present in any alias node. That could be done by
> searching for the highest alias number and give the dynamic devices one
> number higher. Would that be doable?

Dynamic device number is assigned via
- setting id to DEVICE_ID_DYNAMIC, either by driver or by code at top of
eth_register(),
- replacing that with lowest currently-unused number at top of
register_device()

Probably we can add one more magic value that driver could set into
edev->dev.id before calling eth_register(), that will be replaced with
lowest currently-unused number that does not have aliases. However, this
will change eth numbering in existing setups and thus can break them.

Possible option could be a flag in edev that forbids setting/exporting
ethaddr for this device. Doing so for usbnet seems safe. This will fix
my case.

Nikita

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