[PATCH] rcu head debug consider on stack fixup

[Mathieu Desnoyers <mathieu.desnoyers@efficios.com>]

Complain if activation receives a non-initialized object on the stack.

[This patch applies after "tree/tiny rcu: Add debug RCU head objects (v5)"]

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: David S. Miller <davem@davemloft.net>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
CC: akpm@linux-foundation.org
CC: mingo@elte.hu
CC: laijs@cn.fujitsu.com
CC: dipankar@in.ibm.com
CC: josh@joshtriplett.org
CC: dvhltc@us.ibm.com
CC: niv@us.ibm.com
CC: tglx@linutronix.de
CC: peterz@infradead.org
CC: rostedt@goodmis.org
CC: Valdis.Kletnieks@vt.edu
CC: dhowells@redhat.com
CC: eric.dumazet@gmail.com
CC: Alexey Dobriyan <adobriyan@gmail.com>
---
 kernel/rcupdate.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Index: linux.trees.git/kernel/rcupdate.c
===================================================================
--- linux.trees.git.orig/kernel/rcupdate.c	2010-03-29 11:05:35.000000000 -0400
+++ linux.trees.git/kernel/rcupdate.c	2010-03-29 11:06:23.000000000 -0400
@@ -179,8 +179,12 @@ static int rcuhead_fixup_activate(void *
 		 * This is not really a fixup. We just make sure that it is
 		 * tracked in the object tracker.
 		 */
-		debug_object_init(head, &rcuhead_debug_descr);
-		debug_object_activate(head, &rcuhead_debug_descr);
+		if (!object_is_on_stack(head)) {
+			debug_object_init(head, &rcuhead_debug_descr);
+			debug_object_activate(head, &rcuhead_debug_descr);
+			return 0;
+		}
+		WARN_ON_ONCE(1);
 		return 0;
 
 	case ODEBUG_STATE_ACTIVE:
-- 
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com