[libvirt] qemu: migration: shall we abort migration while the guest is rebooting？

[Zhangbo (Oscar)]

Hi all:
  Here's the steps we produce the problem: 
  1 reboot guest with the flag of VIR_DOMAIN_REBOOT_ACPI_POWER_BTN
  2 sleep 1 second (so that the guest is still rebooting, although the API already returned.)
  3 migrate the guest

  The problem is that : the guest failed to migrate to the dest, and crashed on source side.

  We don't bother to dig further into the problem, the root cause we think is that we migrate a guest while it's rebooting.

  So, shall we 
  1 make the reboot JOB LOCK longer enough until the guest has already rebooted(got monitor message from qemu)?
  2 let openstack do the mutex work ?  (has openstack already done this?)
    (I checked openstack codes, and found that openstack uses shutdown and create APIs rather than REBOOT to do the reboot work. So it seems that openstack doesn't take care of this problem nowadays. Am I right? --- see: nova/virt/libvirt/driver.py: _soft_reboot)


  Thanks in advance.

Zhang Bo (Oscar)