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SubjectRe: [PATCH] netns: Coexist with the sysfs limitations
Serge E. Hallyn wrote:
> Quoting Eric W. Biederman (
>> To make testing of the network namespace simpler allow
>> the network namespace code and the sysfs code to be
>> compiled and run at the same time. To do this only
>> virtual devices are allowed in the additional network
>> namespaces and those virtual devices are not placed
>> in the kobject tree.
>> Since virtual devices don't actually do anything interesting
>> hardware wise that needs device management there should
>> be no loss in keeping them out of the kobject tree and
>> by implication sysfs. The gain in ease of testing
>> and code coverage should be significant.
>> I.e. people running distributions that make it next to
>> impossible to boot without sysfs should at be able to
>> boot a test kernel now.
>> Plus no ABIs are harmed with this patch.

>> Signed-off-by: Eric W. Biederman <>
> Duh.
> Tested-by: Serge Hallyn <>
> Acked-by: Serge Hallyn <>

Oh, this patch is short, clean, and the limitation introduced isn't too
annoying for testing netns right now.

At least, my proposal provoked some reactions :)

BTW, there's a second limitation with your patch:
we can't rename the net devices in the additional network namespaces.

In net/core/dev.c, dev_change_name() fails: call to device_rename()
return an (expected) -EINVAL error.
Maybe we should add a test on the net to only call it in init_net?

- err = device_rename(&dev->dev, dev->name);
- if (err) {
- memcpy(dev->name, oldname, IFNAMSIZ);
- return err;
+ if (net == &init_net) {
+ err = device_rename(&dev->dev, dev->name);
+ if (err) {
+ memcpy(dev->name, oldname, IFNAMSIZ);
+ return err;
+ }


Acked-by: Benjamin Thery <>


> Thanks, Eric! Thanks, Benjamin!
> -serge

B e n j a m i n T h e r y - BULL/DT/Open Software R&D

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