Revert "driver core: check start node in klist_iter_init_node"

This reverts commit a15d49fd3094cff90e5410ca454a870e0a722fe1 as that
patch broke the build.

Cc: Hannes Reinecke <[e-mail]>
Reported-by: Stephen Rothwell <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/base/bus.c

···
 	if (!bus)
 		return -EINVAL;
 
-	error = klist_iter_init_node(&bus->p->klist_devices, &i,
-				     (start ? &start->p->knode_bus : NULL));
-	if (!error) {
-		while ((dev = next_device(&i)) && !error)
-			error = fn(dev, data);
-		klist_iter_exit(&i);
-	}
+	klist_iter_init_node(&bus->p->klist_devices, &i,
+			     (start ? &start->p->knode_bus : NULL));
+	while ((dev = next_device(&i)) && !error)
+		error = fn(dev, data);
+	klist_iter_exit(&i);
 	return error;
 }
 EXPORT_SYMBOL_GPL(bus_for_each_dev);
···
 	if (!bus)
 		return NULL;
 
-	if (klist_iter_init_node(&bus->p->klist_devices, &i,
-				 (start ? &start->p->knode_bus : NULL)) < 0)
-		return NULL;
-
+	klist_iter_init_node(&bus->p->klist_devices, &i,
+			     (start ? &start->p->knode_bus : NULL));
 	while ((dev = next_device(&i)))
 		if (match(dev, data) && get_device(dev))
 			break;
···
 		return NULL;
 
 	if (hint) {
-		if (klist_iter_init_node(&subsys->p->klist_devices, &i,
-					 &hint->p->knode_bus) < 0)
-			return NULL;
+		klist_iter_init_node(&subsys->p->klist_devices, &i, &hint->p->knode_bus);
 		dev = next_device(&i);
 		if (dev && dev->id == id && get_device(dev)) {
 			klist_iter_exit(&i);
···
 	if (!bus)
 		return -EINVAL;
 
-	error = klist_iter_init_node(&bus->p->klist_drivers, &i,
-				     start ? &start->p->knode_bus : NULL);
-	if (!error) {
-		while ((drv = next_driver(&i)) && !error)
-			error = fn(drv, data);
-		klist_iter_exit(&i);
-	}
+	klist_iter_init_node(&bus->p->klist_drivers, &i,
+			     start ? &start->p->knode_bus : NULL);
+	while ((drv = next_driver(&i)) && !error)
+		error = fn(drv, data);
+	klist_iter_exit(&i);
 	return error;
 }
 EXPORT_SYMBOL_GPL(bus_for_each_drv);
···
  * otherwise if it is NULL, the iteration starts at the beginning of
  * the list.
  */
-int subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
-			 struct device *start, const struct device_type *type)
+void subsys_dev_iter_init(struct subsys_dev_iter *iter, struct bus_type *subsys,
+			  struct device *start, const struct device_type *type)
 {
 	struct klist_node *start_knode = NULL;
-	int error;
 
 	if (start)
 		start_knode = &start->p->knode_bus;
-	error = klist_iter_init_node(&subsys->p->klist_devices, &iter->ki,
-				     start_knode);
-	if (!error)
-		iter->type = type;
-	return error;
+	klist_iter_init_node(&subsys->p->klist_devices, &iter->ki, start_knode);
+	iter->type = type;
 }
 EXPORT_SYMBOL_GPL(subsys_dev_iter_init);
 

drivers/base/class.c

···
  * otherwise if it is NULL, the iteration starts at the beginning of
  * the list.
  */
-int class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
-			struct device *start, const struct device_type *type)
+void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
+			 struct device *start, const struct device_type *type)
 {
 	struct klist_node *start_knode = NULL;
-	int error;
 
 	if (start)
 		start_knode = &start->knode_class;
-	error = klist_iter_init_node(&class->p->klist_devices, &iter->ki,
-				     start_knode);
-	if (!error)
-		iter->type = type;
-
-	return error;
+	klist_iter_init_node(&class->p->klist_devices, &iter->ki, start_knode);
+	iter->type = type;
 }
 EXPORT_SYMBOL_GPL(class_dev_iter_init);
 
···
 		return -EINVAL;
 	}
 
-	error = class_dev_iter_init(&iter, class, start, NULL);
-	if (!error) {
-		while ((dev = class_dev_iter_next(&iter))) {
-			error = fn(dev, data);
-			if (error)
-				break;
-		}
-		class_dev_iter_exit(&iter);
+	class_dev_iter_init(&iter, class, start, NULL);
+	while ((dev = class_dev_iter_next(&iter))) {
+		error = fn(dev, data);
+		if (error)
+			break;
 	}
+	class_dev_iter_exit(&iter);
+
 	return error;
 }
 EXPORT_SYMBOL_GPL(class_for_each_device);
···
 		return NULL;
 	}
 
-	if (class_dev_iter_init(&iter, class, start, NULL) < 0)
-		return NULL;
-
+	class_dev_iter_init(&iter, class, start, NULL);
 	while ((dev = class_dev_iter_next(&iter))) {
 		if (match(dev, data)) {
 			get_device(dev);

drivers/base/driver.c

···
 	if (!drv)
 		return -EINVAL;
 
-	error = klist_iter_init_node(&drv->p->klist_devices, &i,
-				     start ? &start->p->knode_driver : NULL);
-	if (!error) {
-		while ((dev = next_device(&i)) && !error)
-			error = fn(dev, data);
-		klist_iter_exit(&i);
-	}
+	klist_iter_init_node(&drv->p->klist_devices, &i,
+			     start ? &start->p->knode_driver : NULL);
+	while ((dev = next_device(&i)) && !error)
+		error = fn(dev, data);
+	klist_iter_exit(&i);
 	return error;
 }
 EXPORT_SYMBOL_GPL(driver_for_each_device);
···
 	if (!drv)
 		return NULL;
 
-	if (klist_iter_init_node(&drv->p->klist_devices, &i,
-				 (start ? &start->p->knode_driver : NULL)) < 0)
-		return NULL;
-
+	klist_iter_init_node(&drv->p->klist_devices, &i,
+			     (start ? &start->p->knode_driver : NULL));
 	while ((dev = next_device(&i)))
 		if (match(dev, data) && get_device(dev))
 			break;

include/linux/device.h

···
 	struct klist_iter		ki;
 	const struct device_type	*type;
 };
-int subsys_dev_iter_init(struct subsys_dev_iter *iter,
+void subsys_dev_iter_init(struct subsys_dev_iter *iter,
 			 struct bus_type *subsys,
 			 struct device *start,
 			 const struct device_type *type);
···
 void class_compat_remove_link(struct class_compat *cls, struct device *dev,
 			      struct device *device_link);
 
-extern int class_dev_iter_init(struct class_dev_iter *iter,
-			       struct class *class,
-			       struct device *start,
-			       const struct device_type *type);
+extern void class_dev_iter_init(struct class_dev_iter *iter,
+				struct class *class,
+				struct device *start,
+				const struct device_type *type);
 extern struct device *class_dev_iter_next(struct class_dev_iter *iter);
 extern void class_dev_iter_exit(struct class_dev_iter *iter);
 

include/linux/klist.h

···
 
 
 extern void klist_iter_init(struct klist *k, struct klist_iter *i);
-extern int klist_iter_init_node(struct klist *k, struct klist_iter *i,
+extern void klist_iter_init_node(struct klist *k, struct klist_iter *i,
 				 struct klist_node *n);
 extern void klist_iter_exit(struct klist_iter *i);
 extern struct klist_node *klist_next(struct klist_iter *i);

lib/klist.c

···
  * Similar to klist_iter_init(), but starts the action off with @n,
  * instead of with the list head.
  */
-int klist_iter_init_node(struct klist *k, struct klist_iter *i,
-			 struct klist_node *n)
+void klist_iter_init_node(struct klist *k, struct klist_iter *i,
+			  struct klist_node *n)
 {
-	if (n) {
-		kref_get(&n->n_ref);
-		if (!n->n_klist) {
-			kref_put(&n->n_ref);
-			return -ENODEV;
-		}
-	}
 	i->i_klist = k;
 	i->i_cur = n;
-	return 0;
+	if (n)
+		kref_get(&n->n_ref);
 }
 EXPORT_SYMBOL_GPL(klist_iter_init_node);