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Message-Id: <20220915105046.2404072-3-vladimir.oltean@nxp.com>
Date: Thu, 15 Sep 2022 13:50:41 +0300
From: Vladimir Oltean <vladimir.oltean@....com>
To: netdev@...r.kernel.org
Cc: Vinicius Costa Gomes <vinicius.gomes@...el.com>,
Jamal Hadi Salim <jhs@...atatu.com>,
Cong Wang <xiyou.wangcong@...il.com>,
Jiri Pirko <jiri@...nulli.us>,
"David S. Miller" <davem@...emloft.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Paolo Abeni <pabeni@...hat.com>,
Voon Weifeng <weifeng.voon@...el.com>,
Vladimir Oltean <olteanv@...il.com>,
Kurt Kanzenbach <kurt@...utronix.de>,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 net-next 2/7] net/sched: taprio: taprio_dump and taprio_change are protected by rtnl_mutex
Since the writer-side lock is taken here, we do not need to open an RCU
read-side critical section, instead we can use rtnl_dereference() to
tell lockdep we are serialized with concurrent writes.
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
---
v1->v2: patch is new
net/sched/sch_taprio.c | 14 ++++----------
1 file changed, 4 insertions(+), 10 deletions(-)
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 550afbbae8bc..63cbf856894a 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1486,10 +1486,8 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt,
}
INIT_LIST_HEAD(&new_admin->entries);
- rcu_read_lock();
- oper = rcu_dereference(q->oper_sched);
- admin = rcu_dereference(q->admin_sched);
- rcu_read_unlock();
+ oper = rtnl_dereference(q->oper_sched);
+ admin = rtnl_dereference(q->admin_sched);
/* no changes - no new mqprio settings */
if (!taprio_mqprio_cmp(dev, mqprio))
@@ -1880,9 +1878,8 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb)
struct nlattr *nest, *sched_nest;
unsigned int i;
- rcu_read_lock();
- oper = rcu_dereference(q->oper_sched);
- admin = rcu_dereference(q->admin_sched);
+ oper = rtnl_dereference(q->oper_sched);
+ admin = rtnl_dereference(q->admin_sched);
opt.num_tc = netdev_get_num_tc(dev);
memcpy(opt.prio_tc_map, dev->prio_tc_map, sizeof(opt.prio_tc_map));
@@ -1926,8 +1923,6 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb)
nla_nest_end(skb, sched_nest);
done:
- rcu_read_unlock();
-
return nla_nest_end(skb, nest);
admin_error:
@@ -1937,7 +1932,6 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb)
nla_nest_cancel(skb, nest);
start_error:
- rcu_read_unlock();
return -ENOSPC;
}
--
2.34.1
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