[PATCH] Driver core: kset_find_obj should increment refcount of the found object

kset_find_obj should increment refcount of the found object so users of
the function can safely use returned object
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/base/bus.c

@@ -607,6 +607,8 @@ void put_bus(struct bus_type * bus)
  *
  *	Call kset_find_obj() to iterate over list of buses to
  *	find a bus by name. Return bus if found.
+ *
+ *	Note that kset_find_obj increments bus' reference count.
  */
 
 struct bus_type * find_bus(char * name)

drivers/base/core.c

@@ -378,6 +378,16 @@ int device_for_each_child(struct device * dev, void * data,
 	return error;
 }
 
+/**
+ *	device_find - locate device on a bus by name.
+ *	@name:	name of the device.
+ *	@bus:	bus to scan for the device.
+ *
+ *	Call kset_find_obj() to iterate over list of devices on
+ *	a bus to find device by name. Return device if found.
+ *
+ *	Note that kset_find_obj increments device's reference count.
+ */
 struct device *device_find(const char *name, struct bus_type *bus)
 {
 	struct kobject *k = kset_find_obj(&bus->devices, name);

drivers/pci/hotplug/rpaphp_vio.c

@@ -86,7 +86,14 @@ int register_vio_slot(struct device_node *dn)
 	}
 	slot->dev_type = VIO_DEV;
 	slot->dev.vio_dev = vio_find_node(dn);
-	if (!slot->dev.vio_dev)
+	if (slot->dev.vio_dev) {
+		/*
+		 * rpaphp is the only owner of vio devices and
+		 * does not need extra reference taken by
+		 * vio_find_node
+		 */
+		put_device(&slot->dev.vio_dev->dev);
+	} else
 		slot->dev.vio_dev = vio_register_device_node(dn);
 	if (slot->dev.vio_dev)
 		slot->state = CONFIGURED;

lib/kobject.c

@@ -537,7 +537,8 @@ void kset_unregister(struct kset * k)
  *	@name:	object's name.
  *
  *	Lock kset via @kset->subsys, and iterate over @kset->list,
- *	looking for a matching kobject. Return object if found.
+ *	looking for a matching kobject. If matching object is found
+ *	take a reference and return the object.
  */
 
 struct kobject * kset_find_obj(struct kset * kset, const char * name)
@@ -548,8 +549,8 @@ struct kobject * kset_find_obj(struct kset * kset, const char * name)
 	down_read(&kset->subsys->rwsem);
 	list_for_each(entry,&kset->list) {
 		struct kobject * k = to_kobj(entry);
-		if (kobject_name(k) && (!strcmp(kobject_name(k),name))) {
-			ret = k;
+		if (kobject_name(k) && !strcmp(kobject_name(k),name)) {
+			ret = kobject_get(k);
 			break;
 		}
 	}