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Re: [libvirt] [PATCH] qemu: add macvlan delete to qemuDomainAttachNetDevice cleanup



On 07/08/2013 09:08 AM, Viktor Mihajlovski wrote:
> On 07/02/2013 07:15 PM, Matthew Rosato wrote:
>> On 07/01/2013 06:42 PM, Laine Stump wrote:
>>> On 07/01/2013 11:04 AM, Viktor Mihajlovski wrote:
>>>> From: Matthew Rosato <mjrosato linux vnet ibm com>
>>>
>>> This is a good catch, but incomplete. If you search for other
>>> occurrences of virDomainConfNWFilterTeardown() and
>>> qemuPhysIfaceConnect(), you will find the same problem exists in two
>>> other places in the code:
>>>
>>>     qemuBuildInterfaceCommandLine (during error cleanup, needs to be
>>> called
>>>                                    for the one interface that was
>>> partially
>>>                                    created)
>>>     qemuBuildCommandLine          (during error cleanup, needs to be
>>> called
>>>                                    for all interfaces that were
>>> completely
>>>                                    created (up to last_good_net))
>>>
>>> We really should fix them all in one patch, since they are all the same
>>> problem.
>>
>> Thank you for your comments.  I tested the two cases that you mentioned
>> by forcing errors; in both, the macvtap will be released by code in
>> qemuProcessStop(), which releases any macvtap in the domain's nets list.
>>   Is this sufficient, or did you still want something changed?
>>
> True ... the only other driver function that invokes qemBuildCommandLine
> is connectDomainXMLToNative and here some premonition has prevented
> the allocation of macvtap devices :)
>>>
>>> (Ideally, *all* guest interface setup for each interface should be
>>> handled in a single function, and that function should be in the
>>> network
>>> driver (networkReleaseActualDevice() seems properly situated). That way
>>> it could be put behind an RPC, and the non-privileged libvirtd could
>>> call it too (with proper credentials). That is a larger problem,
>>> though.)
>>>
> I agree, to both parts (proper structure and magnitude of effort).
>
> Laine,
> given that the patch solves the problem at hand and the other cases
> are handled properly: are you OK with the current, simple approach?

Yes. Sorry, I meant to reply, but got sidetracked by something else
while I was in the middle of investigating.

Relying on the code higher up for cleanup is some day going to cause
problems since it's just a coincidence that it currently works, but the
organization is already broken, and what you're doing doesn't make it
any worse (while solving a real problem). I was hoping to persuade you
to do some of the cleanup to make it work correctly on purpose (and
simpler to migrate further to remove all the duplicate teardown code and
put it into a single function that does all teardown for a single
interface), but I guess I'm not the only one who is incredibly busy :-)


>
> The issue for us is that the dangling macvtap device prevents the reuse
> of the interface's MAC address on s390 and there's no libvirt means
> to delete the macvtap interface.
>

ACK and pushed.


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