[libvirt] Question about migration confirm phase

[Jim Fehlig]

I've been investigating a lockd lock ordering bug in a migration error handling 
path in the libxl driver. In the perform phase, the src calls 
virDomainLockProcessPause to release the lock before sending the VM to dst. In 
this case the send fails for other reasons and an attempt is made to reacquire 
the lock with virDomainLockProcessResume. But that fails since the dst has not 
finished cleaning up the failed VM and releasing the lock it acquired when 
starting to receive the VM. My immediate reaction was "why not reacquire the 
lock in the confirm phase", but then I saw my older comment a few lines later in 
the perform phase code

         /*
          * Confirm phase will not be executed if perform fails. End the
          * job started in begin phase.
          */

Is that just a bug in the implementation, or is it intended to skip the confirm 
phase if perform fails?

Regards,
Jim