Description of problem:

Rebooting a Xen guest doesn't always work. After rebooting the guest a random
number of times rebooting stops working and the error message below appears in
/var/log/xen/xend.log.

------------------------------------------------------
[2008-03-14 13:44:17 xend.XendDomainInfo 5491] DEBUG (XendDomainInfo:1559)
XendDomainInfo.destroy: domid=2
[2008-03-14 13:44:17 xend.XendDomainInfo 5491] DEBUG (XendDomainInfo:1567)
XendDomainInfo.destroyDomain(2)
[2008-03-14 13:44:17 xend.XendDomainInfo 5491] ERROR (XendDomainInfo:1863)
Failed to restart domain 1.
Traceback (most recent call last):
File "/usr/lib/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 1849,
in restart
  new_dom.waitForDevices()
File "/usr/lib/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 1762,
in waitForDevices
  self.waitForDevices_(c)
File "/usr/lib/python2.4/site-packages/xen/xend/XendDomainInfo.py", line 1158,
in waitForDevices_
  return self.getDeviceController(deviceClass).waitForDevices()
File "/usr/lib/python2.4/site-packages/xen/xend/server/DevController.py", line
145, in waitForDevices
  return map(self.waitForDevice, self.deviceIDs())
File "/usr/lib/python2.4/site-packages/xen/xend/server/DevController.py", line
155, in waitForDevice
  raise VmError("Device %s (%s) could not be connected. "
VmError: Device 0 (vif) could not be connected. Hotplug scripts not working.
[2008-03-14 13:44:18 xend 5491] DEBUG (DevController:476) hotplugStatusCallback
/local/domain/0/backend/vif/2/0/hotplug-status.
[2008-03-14 13:44:18 xend 5491] DEBUG (DevController:490) hotplugStatusCallback 1.
-----------------------------------------------------

Once the problem has occurred it will continue occurring until the host is
rebooted. Our customer rebooted a guest 372 times before the problem occured,
however the number of reboots required varies. The guest appears to shutdown
correctly, but cannot be started. The problem doesn't occur on RHEL 5.1. The
problem occurs with both PV and FV guests, and on IA64 and x86 architectures
(x86_64 hasn't been confirmed).

Version-Release number of selected component (if applicable):
RHEL 5.2 beta

How reproducible:
100%

Step to Reproduce:
# xm reboot
or 'reboot' from within the guest

Actual Results:
Eventually the guest will shutdown and won't be able to restart.

Expected Results:
Guest always reboots correctly.

Additional info: