idr_replace
old = idr_replace(&fpriv->bo_list_handles, list, handle);
idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
obj = idr_replace(&filp->object_idr, NULL, handle);
obj = idr_replace(&file_priv->object_idr, obj, handle);
idr_replace(&dev->mode_config.object_idr, obj, obj->id);
void *idr_replace(struct idr *, void *, unsigned long);