add task to freezer cgroup

diff --git a/lxcsu b/lxcsu
index 8e0c8a6..f794b88 100644 (file)
--- a/lxcsu
+++ b/lxcsu
@@ -69,6 +69,20 @@ except:
     print "Error assigning resources: %s"%slice_name
     exit(1)
 
+# 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)
+
 r1 = setns.chcontext('/proc/%s/ns/utc'%pid)
 r2 = setns.chcontext('/proc/%s/ns/ipc'%pid)
 path = '/proc/%s/ns/net'%pid