lockdep: fix debug_show_all_locks()

fix the oops that can be seen in:

   http://bugzilla.kernel.org/attachment.cgi?id=13828&action=view

it is not safe to print the locks of running tasks.

(even with this fix we have a small race - but this is a debug
 function after all.)
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

kernel/lockdep.c

@@ -3173,6 +3173,13 @@ void debug_show_all_locks(void)
 		printk(" locked it.\n");
 
 	do_each_thread(g, p) {
+		/*
+		 * It's not reliable to print a task's held locks
+		 * if it's not sleeping (or if it's not the current
+		 * task):
+		 */
+		if (p->state == TASK_RUNNING && p != current)
+			continue;
 		if (p->lockdep_depth)
 			lockdep_print_held_locks(p);
 		if (!unlock)