慢慢欣赏linux 网络协议栈三监听链路状态

原创已于 2022-01-25 15:11:30 修改 · 469 阅读

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#linux #网络协议 #运维

于 2019-03-31 08:04:05 首次发布

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本文介绍了链接监视器的任务队列处理流程，包括如何通过延迟工作队列唤醒处理网络设备状态变化的消息，以及如何针对紧急和非紧急事件进行调度。同时，详细解释了在网络设备载波状态改变时触发事件的具体实现。

唤醒任务队列处理消息

static DECLARE_DELAYED_WORK(linkwatch_work, linkwatch_event);
=>void linkwatch_event(struct work_struct *dummy)
	rtnl_lock();
	__linkwatch_run_queue(time_after(linkwatch_nextevent, jiffies));
	=>void __linkwatch_run_queue(int urgent_only)
		list_splice_init(&lweventlist, &wrk);
		while (!list_empty(&wrk))
			dev = list_first_entry(&wrk, struct net_device, link_watch_list);
			list_del_init(&dev->link_watch_list);

			if (urgent_only && !linkwatch_urgent_event(dev)) {
				list_add_tail(&dev->link_watch_list, &lweventlist);
				continue;
			}

			linkwatch_do_dev(dev);
		
		if (!list_empty(&lweventlist))
			linkwatch_schedule_work(0);
			
	rtnl_unlock();

状态变化添加消息

void netif_carrier_on(struct net_device *dev)
	linkwatch_fire_event(dev);
	=>void linkwatch_fire_event(struct net_device *dev)
		bool urgent = linkwatch_urgent_event(dev);
		linkwatch_add_event(dev);
		=>void linkwatch_add_event(struct net_device *dev)
			if (list_empty(&dev->link_watch_list)) 
				list_add_tail(&dev->link_watch_list, &lweventlist);
				dev_hold(dev);

		linkwatch_schedule_work(urgent);
	if (netif_running(dev))
		__netdev_watchdog_up(dev);