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pkt_sched: set root qdisc before change() in attach_default_qdiscs() 

After commit 95dc19299f ("pkt_sched: give visibility to mq slave
qdiscs") we call disc_list_add() while the device qdisc might be
the noop_qdisc one.

This shows up as duplicates in "tc qdisc show", as all inactive devices
point to noop_qdisc.

Fix this by setting dev->qdisc to the new qdisc before calling
ops->change() in attach_default_qdiscs()

Add a WARN_ON_ONCE() to catch any future similar problem.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2013-12-12 15:41:56 -08:00 committed by David S. Miller
parent 59bcaed5f7
commit e57a784d8c
2 changed files with 5 additions and 2 deletions
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5
net/sched/sch_api.c
View File

@ -273,8 +273,11 @@ static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
void qdisc_list_add(struct Qdisc *q)
{
struct Qdisc *root = qdisc_dev(q)->qdisc;
WARN_ON_ONCE(root == &noop_qdisc);
if ((q->parent != TC_H_ROOT) && !(q->flags & TCQ_F_INGRESS))
list_add_tail(&q->list, &qdisc_dev(q)->qdisc->list);
list_add_tail(&q->list, &root->list);
}
EXPORT_SYMBOL(qdisc_list_add);

2
net/sched/sch_generic.c
View File

@ -718,8 +718,8 @@ static void attach_default_qdiscs(struct net_device *dev)
} else {
qdisc = qdisc_create_dflt(txq, &mq_qdisc_ops, TC_H_ROOT);
if (qdisc) {
qdisc->ops->attach(qdisc);
dev->qdisc = qdisc;
qdisc->ops->attach(qdisc);
}
}
}