bfq_stat_exit
bfq_stat_exit(&stats->time);
bfq_stat_exit(&stats->avg_queue_size_sum);
bfq_stat_exit(&stats->avg_queue_size_samples);
bfq_stat_exit(&stats->dequeue);
bfq_stat_exit(&stats->group_wait_time);
bfq_stat_exit(&stats->idle_time);
bfq_stat_exit(&stats->empty_time);