From e57a784d8cae429f5b697fe55abf420181d9ff09 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
Date: Thu, 12 Dec 2013 15:41:56 -0800
Subject: [PATCH] pkt_sched: set root qdisc before change() in
attach_default_qdiscs()
After commit 95dc19299f74 ("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>
---
net/sched/sch_api.c | 5 ++++-
net/sched/sch_generic.c | 2 +-
2 files changed, 5 insertions(+), 2 deletions(-)
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 547b4a88ae2aa..c31190e29b902 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -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);
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 6a91d7d48ade4..32bb942d2faad 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -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);
}
}
}
--
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