[libvirt] [PATCH] Fix deadlock in QEMU close callback APIs

[Jiri Denemark]

On Thu, Feb 28, 2013 at 13:33:31 +0000, Daniel P. Berrange wrote:
> From: "Daniel P. Berrange" <berrange at redhat.com>
> 
> There is a lock ordering problem in the QEMU close callback
> APIs.
> 
> When starting a guest we have a lock on the VM. We then
> set a autodestroy callback, which acquires a lock on the
> close callbacks.
> 
> When running auto-destroy, we obtain a lock on the close
> callbacks, then run each callbacks - which obtains a lock
> on the VM.
> 
> This causes deadlock if anyone tries to start a VM, while
> autodestroy is taking place.
> 
> The fix is to do autodestroy in 2 phases. First obtain
> all the callbacks and remove them from the list under
> the close callback lock. Then invoke each callback
> from outside the close callback lock.

ACK (with the virnetlink hunk removed, of course).

Jirka