Commit 2ba2506c authored Mar 28, 2008 by Herbert Xu Committed by David S. Miller Mar 28, 2008

[NET]: Add preemption point in qdisc_run



The qdisc_run loop is currently unbounded and runs entirely in a
softirq.  This is bad as it may create an unbounded softirq run.

This patch fixes this by calling need_resched and breaking out if
necessary.

It also adds a break out if the jiffies value changes since that would
indicate we've been transmitting for too long which starves other
softirqs.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

parent 32aced75

net/sched/sch_generic.c

+15 −3

Original line number	Diff line number	Diff line
		@@ -184,10 +184,22 @@ static inline int qdisc_restart(struct net_device *dev)

		void __qdisc_run(struct net_device *dev)
		{
		do {
		if (!qdisc_restart(dev))
		unsigned long start_time = jiffies;

		while (qdisc_restart(dev)) {
		if (netif_queue_stopped(dev))
		break;
		} while (!netif_queue_stopped(dev));

		/*
		* Postpone processing if
		* 1. another process needs the CPU;
		* 2. we've been doing it for too long.
		*/
		if (need_resched() \|\| jiffies != start_time) {
		netif_schedule(dev);
		break;
		}
		}

		clear_bit(__LINK_STATE_QDISC_RUNNING, &dev->state);
		}