[Devel] Re: [PATCH] netns: Delete virtual interfaces during namespace cleanup

[Eric W. Biederman]

Pavel Emelyanov <xemul at openvz.org> writes:

> I remember that I promised to prepare the wait-extending patch. But I
> haven't manage to find time for this, sorry :( In a month or two I will
> finish one time-hungry task and hopefully be able to do it.
>
> As far as this particular patch is concerned.
>
> All the virtual devices we have now in namespaces (vlan and tunnels)
> kill themselves *before* this code is called. But even if we try to
> move this destruction from modules to here, we'll be in a tricky
> situation, when the e.g. ipip module has already kfree-d the net_ipip
> structure, while none of ipip devices are released yet.
>
> If we try to look in the future - if we ever have a virtual device
> driver, that will be able to create its devices in namespace, we'll
> have to destroy all these devices *before* (or inside) this driver's
> net->exit callback is called, but this patch dies the ->dellink call
> at the very end, i.e. *after* any potential ->exit callback.
>
> Eric - did you see any device, that was ->dellink-ed by this patch?

macvlan, veth, and dummy interfaces.  Basically
everything I use this deletes the virtual interfaces, instead
of sending them back to the initial network namespace.

>From the looks of the code vlans are also be handled.

Things like tun/tap and ipip are handled in the exit methods and I
have no problem with that, although I do wonder if we are handling
moving or refusing to move them between namespaces properly.

For devices that don't need a dedicated virtual interface in
every network namespace this certainly looks like the easiest
way to handle them, as the driver doesn't need to a thing
about network namespaces and the right thing just happens.

Eric
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