Task Control Groups: simple task cgroup debug info subsystem

This example subsystem exports debugging information as an aid to diagnosing
refcount leaks, etc, in the cgroup framework.

Signed-off-by: Paul Menage <menage@google.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h
index a568b87..cbadc3b 100644
--- a/include/linux/cgroup_subsys.h
+++ b/include/linux/cgroup_subsys.h
@@ -19,4 +19,8 @@
 
 /* */
 
+#ifdef CONFIG_CGROUP_DEBUG
+SUBSYS(debug)
+#endif
+
 /* */