net: link_watch: prevent starvation when processing linkwatch wq (27ba4059) · Commits · 戴 / test

When user has configured a large number of virtual netdev, such as 4K vlans, the carrier on/off operation of the real netdev will also cause it's virtual netdev's link state to be processed in linkwatch. Currently, the processing is done in a work queue, which may cause rtnl locking starvation problem and worker starvation problem for other work queue, such as irqfd_inject wq. This patch releases the cpu when link watch worker has processed a fixed number of netdev' link watch event, and schedule the work queue again when there is still link watch event remaining. Signed-off-by:

Yunsheng Lin <linyunsheng@huawei.com> Signed-off-by:

David S. Miller <davem@davemloft.net>

net/core/link_watch.c

+12 −1

Original line number	Diff line number	Diff line
		@@ -163,9 +163,16 @@ static void linkwatch_do_dev(struct net_device *dev)

		static void __linkwatch_run_queue(int urgent_only)
		{
		#define MAX_DO_DEV_PER_LOOP 100

		int do_dev = MAX_DO_DEV_PER_LOOP;
		struct net_device *dev;
		LIST_HEAD(wrk);

		/* Give urgent case more budget */
		if (urgent_only)
		do_dev += MAX_DO_DEV_PER_LOOP;

		/*
		* Limit the number of linkwatch events to one
		* per second so that a runaway driver does not
		@@ -184,7 +191,7 @@ static void __linkwatch_run_queue(int urgent_only)
		spin_lock_irq(&lweventlist_lock);
		list_splice_init(&lweventlist, &wrk);

		while (!list_empty(&wrk)) {
		while (!list_empty(&wrk) && do_dev > 0) {

		dev = list_first_entry(&wrk, struct net_device, link_watch_list);
		list_del_init(&dev->link_watch_list);
		@@ -195,9 +202,13 @@ static void __linkwatch_run_queue(int urgent_only)
		}
		spin_unlock_irq(&lweventlist_lock);
		linkwatch_do_dev(dev);
		do_dev--;
		spin_lock_irq(&lweventlist_lock);
		}

		/* Add the remaining work back to lweventlist */
		list_splice_init(&wrk, &lweventlist);

		if (!list_empty(&lweventlist))
		linkwatch_schedule_work(0);
		spin_unlock_irq(&lweventlist_lock);

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