unregister_dcbevent_notifier
unregister_dcbevent_notifier(&cxgb4_dcb_change);
unregister_dcbevent_notifier(&dcb_notifier);
unregister_dcbevent_notifier(&cxgbit_dcbevent_nb);
int unregister_dcbevent_notifier(struct notifier_block *nb);
EXPORT_SYMBOL(unregister_dcbevent_notifier);