o2hb_register_callback
EXPORT_SYMBOL_GPL(o2hb_register_callback);
int o2hb_register_callback(const char *region_uuid,
ret = o2hb_register_callback(NULL, &o2net_hb_up);
ret = o2hb_register_callback(NULL, &o2net_hb_down);
status = o2hb_register_callback(dlm->name, &dlm->dlm_hb_down);
status = o2hb_register_callback(dlm->name, &dlm->dlm_hb_up);