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.
Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
96b893f092