lockdep: Implement lockdep_count_*ward_deps by BFS

Implement lockdep_count_{for,back}ward using BFS.
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1246201486-7308-8-git-send-email-tom.leiming@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

kernel/lockdep.c

@@ -1115,61 +1115,59 @@ static noinline int print_bfs_bug(int ret)
 	return 0;
 }
 
-unsigned long __lockdep_count_forward_deps(struct lock_class *class,
-					   unsigned int depth)
+static int noop_count(struct lock_list *entry, void *data)
 {
-	struct lock_list *entry;
-	unsigned long ret = 1;
+	(*(unsigned long *)data)++;
+	return 0;
+}
 
-	if (lockdep_dependency_visit(class, depth))
-		return 0;
+unsigned long __lockdep_count_forward_deps(struct lock_list *this)
+{
+	unsigned long  count = 0;
+	struct lock_list *uninitialized_var(target_entry);
 
-	/*
-	 * Recurse this class's dependency list:
-	 */
-	list_for_each_entry(entry, &class->locks_after, entry)
-		ret += __lockdep_count_forward_deps(entry->class, depth + 1);
+	__bfs_forwards(this, (void *)&count, noop_count, &target_entry);
 
-	return ret;
+	return count;
 }
-
 unsigned long lockdep_count_forward_deps(struct lock_class *class)
 {
 	unsigned long ret, flags;
+	struct lock_list this;
+
+	this.parent = NULL;
+	this.class = class;
 
 	local_irq_save(flags);
 	__raw_spin_lock(&lockdep_lock);
-	ret = __lockdep_count_forward_deps(class, 0);
+	ret = __lockdep_count_forward_deps(&this);
 	__raw_spin_unlock(&lockdep_lock);
 	local_irq_restore(flags);
 
 	return ret;
 }
 
-unsigned long __lockdep_count_backward_deps(struct lock_class *class,
-					    unsigned int depth)
+unsigned long __lockdep_count_backward_deps(struct lock_list *this)
 {
-	struct lock_list *entry;
-	unsigned long ret = 1;
+	unsigned long  count = 0;
+	struct lock_list *uninitialized_var(target_entry);
 
-	if (lockdep_dependency_visit(class, depth))
-		return 0;
-	/*
-	 * Recurse this class's dependency list:
-	 */
-	list_for_each_entry(entry, &class->locks_before, entry)
-		ret += __lockdep_count_backward_deps(entry->class, depth + 1);
+	__bfs_backwards(this, (void *)&count, noop_count, &target_entry);
 
-	return ret;
+	return count;
 }
 
 unsigned long lockdep_count_backward_deps(struct lock_class *class)
 {
 	unsigned long ret, flags;
+	struct lock_list this;
+
+	this.parent = NULL;
+	this.class = class;
 
 	local_irq_save(flags);
 	__raw_spin_lock(&lockdep_lock);
-	ret = __lockdep_count_backward_deps(class, 0);
+	ret = __lockdep_count_backward_deps(&this);
 	__raw_spin_unlock(&lockdep_lock);
 	local_irq_restore(flags);