skb form netif_rx to netif_receive_skb

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最新推荐文章于 2023-04-25 16:39:43 发布

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分类专栏： C语言文章标签： linux 驱动

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1.函数net_dev_init 网络模块的核心处理模块.

static int __init net_dev_init(void)
{
	int i, rc = -ENOMEM;

	BUG_ON(!dev_boot_phase);
/*初始化proc文件系统,*/
	if (dev_proc_init())
		goto out;
/*向sysfs注册为net类，这样会创建/sys/class/net目录，在该目录下每个已注册的网络设备都会有一个子目录，包含很多文件*/
	if (netdev_kobject_init())
		goto out;

	INIT_LIST_HEAD(&ptype_all);
/*协议处理例程向量ptypes_base初始化，用于分离入口流量的多路合并传输*/ 
	for (i = 0; i < PTYPE_HASH_SIZE; i++)
		INIT_LIST_HEAD(&ptype_base[i]);

	INIT_LIST_HEAD(&offload_base);
	if (register_pernet_subsys(&netdev_net_ops))
		goto out;
/*初始化数据包接收队列（软中断队列）
/*遍历每一个CPU，取得它的softnet_data，其实它是一个struct softnet_data的Per-CPU变量*/
	for_each_possible_cpu(i) {
       /*取得第i个CPU的softnet_data也就是软中断的数据队列*/
		struct softnet_data *sd = &per_cpu(softnet_data, i);
		memset(sd, 0, sizeof(*sd));
        /*初始化对列头部*/
		skb_queue_head_init(&sd->input_pkt_queue);
		skb_queue_head_init(&sd->process_queue);
		sd->completion_queue = NULL;
		INIT_LIST_HEAD(&sd->poll_list);
		sd->output_queue = NULL;
		sd->output_queue_tailp = &sd->output_queue;
#ifdef CONFIG_RPS
		sd->csd.func = rps_trigger_softirq;
		sd->csd.info = sd;
		sd->csd.flags = 0;
		sd->cpu = i;
#endif
/*把backlog的轮询函数初始化为 process_backlog该函数来处理传统接口使用的输入队列的报文这里是重点，数据包走向netif_receive_skb全靠process_backlog ，process_backlog函数是个什么鬼，会在后面讲到*/
		 sd->backlog.poll = process_backlog;

          /*backlog 轮询函数一次可以处理的报文上限个数*/
		sd->backlog.weight = weight_p;
		sd->backlog.gro_list = NULL;
		sd->backlog.gro_count = 0;
	}

	dev_boot_phase = 0;

	/* The loopback device is special if any other network devices
	 * is present in a network namespace the loopback device must
	 * be present. Since we now dynamically allocate and free the
	 * loopback device ensure this invariant is maintained by
	 * keeping the loopback device as the first device on the
	 * list of network devices.  Ensuring the loopback devices
	 * is the first device that appears and the last network device
	 * that disappears.
	 */
	if (register_pernet_device(&loopback_net_ops))
		goto out;

	if (register_pernet_device(&default_device_ops))
		goto out;

/*注册接收，发送软中断*/
	open_softirq(NET_TX_SOFTIRQ, net_tx_action);
	open_softirq(NET_RX_SOFTIRQ, net_rx_action);

	/*注册cpu回调函数，CPU入口队列中的缓冲区出列，然后传给netif_rx函数 */
hotcpu_notifier(dev_cpu_callback, 0);
	dst_init();
	rc = 0;
out:
	return rc;
}