struct softnet_data
{struct net_device       *output_queue;//收报队列，这个队列是给传统收报方法兼容新收报架构用的(backlog_dev)，用来模拟NAPI的struct sk_buff_head     input_pkt_queue;//用于收包的net_devicestruct list_head        poll_list;struct sk_buff          *completion_queue;//backlog_dev是一个伪造的net_device用来来处理input_pkt_queue里的数据struct net_device       backlog_dev;    /* Sorry. 8) */
};

static void net_rx_action(struct softirq_action *h)
{struct softnet_data *queue = &__get_cpu_var(softnet_data);unsigned long start_time = jiffies;//预算，所有网卡的总配额int budget = netdev_budget;void *have;local_irq_disable();while (!list_empty(&queue->poll_list)) {struct net_device *dev;//预算用完了，或者时间太长了，跳出等下一轮处理if (budget <= 0 || jiffies - start_time > 1)goto softnet_break;local_irq_enable();dev = list_entry(queue->poll_list.next,struct net_device, poll_list);have = netpoll_poll_lock(dev);if (dev->quota <= 0 || dev->poll(dev, &budget)) {netpoll_poll_unlock(have);local_irq_disable();//没处理完，放到队尾准备下次处理，注意是list_move_tai，不是//list_insert_taillist_move_tail(&dev->poll_list, &queue->poll_list);if (dev->quota < 0)dev->quota += dev->weight;elsedev->quota = dev->weight;} else {netpoll_poll_unlock(have);dev_put(dev);local_irq_disable();}}//省略部分代码
}

static int __init net_dev_init(void)
{
//省略部分代码
        for_each_possible_cpu(i) {struct softnet_data *queue;queue = &per_cpu(softnet_data, i);skb_queue_head_init(&queue->input_pkt_queue);queue->completion_queue = NULL;INIT_LIST_HEAD(&queue->poll_list);set_bit(__LINK_STATE_START, &queue->backlog_dev.state);queue->backlog_dev.weight = weight_p;queue->backlog_dev.poll = process_backlog;atomic_set(&queue->backlog_dev.refcnt, 1);}
}