+# If the slice is frozen, then we'll get an EBUSY when trying to write to the task
+# list for the freezer cgroup. Since the user couldn't do anything anyway, it's best
+# in this case to error out the shell. (an alternative would be to un-freeze it,
+# add the task, and re-freeze it)
+try:
+ f=open('/sys/fs/cgroup/freezer/libvirt/lxc/%s/tasks'%(slice_name),'w')
+ f.write(str(os.getpid()))
+ # note: we need to call f.close() explicitly, or we'll get an exception in
+ # the object destructor, which will not be caught
+ f.close()
+except:
+ print "Error adding task to freezer cgroup. Slice is probably frozen: %s" % slice_name
+ exit(1)