Re: [libvirt] [PATCH v4 4/7] Add network events to the remote driver
On 01/09/2014 07:50 PM, Eric Blake wrote:
On 12/12/2013 07:30 AM, Cedric Bosdonnat wrote:
> Hi John,
>
>>> + event = virNetworkEventLifecycleNew(net->name, net->uuid,
msg->event);
>>> + virNetworkFree(net);
>>> + remoteDomainEventQueue(priv, event);
>> Essentially - you need to check for NULL event.
>
> Sure, but the weird thing it that it should also complain on the similar
> functions for domain events, right above this one in the same file.
Revisiting this. The problem can only happen on OOM situations, so it's
not that likely to hit in real life; but we should indeed fix our code.
I think the easiest way is to fix remoteDomainEventQueue to gracefully
do nothing on a NULL event (events are best effort, and if OOM occurs,
skipping event delivery is an acceptable action, since we have no way of
reporting the error). I'll post a patch.
Actually, it turns out we are quite lucky - appending a NULL event to
the queue had no ill effects, because when checking for what callbacks
to dispatch, our first use of events was an early exit if
(!virObjectIsClass(event, cb->klass)). So the ATTRIBUTE_NONNULL could
actually be deleted - but that in turn implies we have a lot of code
that checks for non-null events before queueing them up which could also
be simplified. And even if we did that, queueing a NULL event is a
waste of resources compared to just avoiding them altogether.
--
Eric Blake eblake redhat com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
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