DIR_Callback *cb, *cbPrev;
DIR_Callback *cb, *cbPrev=nsnull;
PRBool DIR_DeregisterNotificationCallback(DIR_NOTIFICATION_FN fn, void *inst_data){	DIR_Callback *cb, *cbPrev;	for (cb = dir_CallbackList; cb && cb->fn != fn && cb->data != inst_data; cb = cb->next)		cbPrev = cb;	if (cb == nsnull)		return PR_FALSE;	if (cb == dir_CallbackList)		dir_CallbackList = cb->next;	else		cbPrev->next = cb->next;	PR_Free(cb);	return PR_TRUE;}