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net/sched: taprio: taprio_dump and taprio_change are protected by rtnl_mutex

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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@nxp.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Vladimir Oltean 2022-09-15 13:50:41 +03:00 committed by Jakub Kicinski
parent c8cbe123be
commit 18cdd2f099
1 changed files with 4 additions and 10 deletions
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14
net/sched/sch_taprio.c
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@ -1484,10 +1484,8 @@ 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))
@ -1878,9 +1876,8 @@ 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));
@ -1924,8 +1921,6 @@ 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:
@ -1935,7 +1930,6 @@ static int taprio_dump(struct Qdisc *sch, struct sk_buff *skb)
nla_nest_cancel(skb, nest);
start_error:
rcu_read_unlock();
return -ENOSPC;
}