the task_state is migrating if compare cpu failed

[wanghong]

Code version:
The lastest version of master

API version:
V2

Compute driver:
libvirt.LibvirtDriver

Libvert type:
KVM

Steps:
1.Create a vm
2.Live migrate the vm to the other host

Bugs:
The task_state of the instance is "migrating" if compare cpu failed. So, i can not migrate the vm anymore.

[John Garbutt (johngarbutt)]

compare cpu should cause the state to revert to Active leaving a message in the instance actions.

It would be helpful to get a traceback for this (possible from nova scheduler). I suspect its an unexpected exception, so the task state doesn't get reverted.

[Andres Buraschi (andres-buraschi)]

Looks like this is related to:
https://bugs.launchpad.net/nova/+bug/1082414

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/122119

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/122119
Committed: https://git.openstack.org/cgit/openstack/nova/commit/?id=ce16d34722475af51592d7ec54267f368d440c3f
Submitter: Jenkins
Branch: master

commit ce16d34722475af51592d7ec54267f368d440c3f
Author: Pawel Koniszewski <email address hidden>
Date: Tue Mar 3 20:24:22 2015 -0500

    Revert instance task_state when compareCPU fails

    If compareCPU fails, libvirt will throw exception libvirtError.
    Libvirt driver catches this exception and rethrows it, however
    conductor manager doesn't expect such exception. This causes
    problem with instance task state - it is stuck in MIGRATION state.

    Because compareCPU method is part of live migration pre-checks,
    this patch changes exception that is reraised in libvirt driver
    from libvirt.libvirtError to exception.MigrationPreCheckError.

    This change also adds unit tests for compareCPU method.

    Change-Id: If7b614c643b172a6b05a30075769b851343984d4
    Closes-Bug: #1249992
    Co-Authored-By: Pawel Koniszewski <email address hidden>