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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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