Re: Bugreport: macvlan device choosing wrong parent device

[Ulrich Ölmann <u oelmann pengutronix de>]

On Tue, Sep 26, 2017 at 03:23:15PM +0200, Beniamino Galvani wrote:
> On Tue, Sep 26, 2017 at 09:36:44AM +0200, Ulrich Ölmann wrote:
> > [...]
> > It looks like NetworkManager does not create the devices in the correct order in
> > contrast to what has been done manually before restarting NetworkManager. This
> > behaviour is only seen if the parent is referenced via a UUID. Using an
> > interface name instead ("parent=eth1"), everything is fine.
>
> Hi,
>
> as it is currently implemented, "parent=$UUID" in the connection file
> means that the parent device will be the device on which connection
> $UUID is currently active or, if none, any device compatibile with
> $UUID; there isn't any sort of temporal dependency implied by the
> property.

Ah, okay. I implicitely assumed that NetworkManager applies some ordering with
respect to device creation by this property - thanks for clarifying this.

> Since connection 7ac61f21-bf59-4c4c-ae38-51ce131b2afc does not specify
> an interface name, at startup NM can match it with any interface and
> chooses the wrong (unmanaged) one. This is a bug and should be easy to
> fix, as in the patch below.

I applied your patch and NetworkManager avoids the unmanaged device eth0 to
instead create the virtual MAC VLAN device on top of eth1 now. Great! :-)
Looking into the journal, however, I still see a warning saying

    manager: (link-local) can't register the device with manager: A device with ifindex 10 already exists

Do we have to expect any side-effects because of this?

> As you already found, setting parent=$INTERFACE should work around
> this bug, as well as setting the interface name in the parent
> connection.

Thanks for your quick and constructive response, Beniamino!

Best regards
Ulrich
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