| Date | Wed, 16 Apr 2008 18:01:58 -0700 | From | Chris Wright <> | Subject | NET: Add preemption point in qdisc_run |
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-stable review patch. If anyone has any objections, please let us know. ---------------------
From: Herbert Xu <herbert@gondor.apana.org.au>
Upstream commit: 2ba2506ca7ca62c56edaa334b0fe61eb5eab6ab0
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> Signed-off-by: Chris Wright <chrisw@sous-sol.org> --- net/sched/sch_generic.c | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-)
--- a/net/sched/sch_generic.c +++ b/net/sched/sch_generic.c @@ -178,10 +178,22 @@ static inline int qdisc_restart(struct n 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; + + /* + * 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; - } while (!netif_queue_stopped(dev)); + } + } clear_bit(__LINK_STATE_QDISC_RUNNING, &dev->state); } --
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