* device_initialize - init device structure.
* @dev: device.
*
- * This prepares the device for use by other layers,
- * including adding it to the device hierarchy.
+ * This prepares the device for use by other layers by initializing
+ * its fields.
* It is the first half of device_register(), if called by
- * that, though it can also be called separately, so one
- * may use @dev's fields (e.g. the refcount).
+ * that function, though it can also be called separately, so one
+ * may use @dev's fields. In particular, get_device()/put_device()
+ * may be used for reference counting of @dev after calling this
+ * function.
+ *
+ * NOTE: Use put_device() to give up your reference instead of freeing
+ * @dev directly once you have called this function.
*/
void device_initialize(struct device *dev)
{
klist_init(&dev->klist_children, klist_children_get,
klist_children_put);
INIT_LIST_HEAD(&dev->dma_pools);
- INIT_LIST_HEAD(&dev->node);
init_MUTEX(&dev->sem);
spin_lock_init(&dev->devres_lock);
INIT_LIST_HEAD(&dev->devres_head);
* This is part 2 of device_register(), though may be called
* separately _iff_ device_initialize() has been called separately.
*
- * This adds it to the kobject hierarchy via kobject_add(), adds it
+ * This adds @dev to the kobject hierarchy via kobject_add(), adds it
* to the global and sibling lists for the device, then
* adds it to the other relevant subsystems of the driver model.
+ *
+ * NOTE: _Never_ directly free @dev after calling this function, even
+ * if it returned an error! Always use put_device() to give up your
+ * reference instead.
*/
int device_add(struct device *dev)
{
if (dev->class) {
mutex_lock(&dev->class->p->class_mutex);
/* tie the class to the device */
- list_add_tail(&dev->node, &dev->class->p->class_devices);
+ klist_add_tail(&dev->knode_class,
+ &dev->class->p->class_devices);
/* notify any interfaces that the device is here */
list_for_each_entry(class_intf,
* I.e. you should only call the two helpers separately if
* have a clearly defined need to use and refcount the device
* before it is added to the hierarchy.
+ *
+ * NOTE: _Never_ directly free @dev after calling this function, even
+ * if it returned an error! Always use put_device() to give up the
+ * reference initialized in this function instead.
*/
int device_register(struct device *dev)
{
if (class_intf->remove_dev)
class_intf->remove_dev(dev, class_intf);
/* remove the device from the class list */
- list_del_init(&dev->node);
+ klist_del(&dev->knode_class);
mutex_unlock(&dev->class->p->class_mutex);
}
device_remove_file(dev, &uevent_attr);
return dev;
error:
- kfree(dev);
+ put_device(dev);
return ERR_PTR(retval);
}
EXPORT_SYMBOL_GPL(device_create_vargs);
* device_rename - renames a device
* @dev: the pointer to the struct device to be renamed
* @new_name: the new name of the device
+ *
+ * It is the responsibility of the caller to provide mutual
+ * exclusion between two different calls of device_rename
+ * on the same device to ensure that new_name is valid and
+ * won't conflict with other devices.
*/
int device_rename(struct device *dev, char *new_name)
{