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net/sched: mq_prio: no longer acquire qdisc spinlocks in mqprio_dump()

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Prepare mqprio_dump() for RTNL avoidance.

Use RCU instead of RTNL, and no longer acquire each children spinlock.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Link: https://patch.msgid.link/20260510091455.4039245-8-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2026-05-10 09:14:54 +00:00 committed by Jakub Kicinski
parent 4f07179f40
commit bb19ce4c43
1 changed files with 24 additions and 13 deletions
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37
net/sched/sch_mqprio.c
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@ -551,35 +551,46 @@ static int mqprio_dump_tc_entries(struct mqprio_sched *priv,
static int mqprio_dump(struct Qdisc *sch, struct sk_buff *skb)
{
struct net_device *dev = qdisc_dev(sch);
struct mqprio_sched *priv = qdisc_priv(sch);
struct nlattr *nla = (struct nlattr *)skb_tail_pointer(skb);
struct mqprio_sched *priv = qdisc_priv(sch);
struct net_device *dev = qdisc_dev(sch);
struct gnet_stats_queue qstats = { 0 };
struct gnet_stats_basic_sync bstats;
struct tc_mqprio_qopt opt = { 0 };
const struct Qdisc *qdisc;
unsigned int qlen = 0;
struct Qdisc *qdisc;
unsigned int ntx;
qlen = 0;
gnet_stats_basic_sync_init(&sch->bstats);
memset(&sch->qstats, 0, sizeof(sch->qstats));
gnet_stats_basic_sync_init(&bstats);
/* MQ supports lockless qdiscs. However, statistics accounting needs
* to account for all, none, or a mix of locked and unlocked child
* qdiscs. Percpu stats are added to counters in-band and locking
* qdisc totals are added at end.
*/
rcu_read_lock();
for (ntx = 0; ntx < dev->num_tx_queues; ntx++) {
qdisc = rtnl_dereference(netdev_get_tx_queue(dev, ntx)->qdisc_sleeping);
spin_lock_bh(qdisc_lock(qdisc));
qdisc = rcu_dereference(netdev_get_tx_queue(dev, ntx)->qdisc_sleeping);
gnet_stats_add_basic(&sch->bstats, qdisc->cpu_bstats,
&qdisc->bstats, false);
gnet_stats_add_queue(&sch->qstats, qdisc->cpu_qstats,
gnet_stats_add_basic(&bstats, qdisc->cpu_bstats,
&qdisc->bstats, true);
gnet_stats_add_queue(&qstats, qdisc->cpu_qstats,
&qdisc->qstats);
qlen += qdisc_qlen_lockless(qdisc);
spin_unlock_bh(qdisc_lock(qdisc));
}
rcu_read_unlock();
spin_lock_bh(qdisc_lock(sch));
_bstats_set(&sch->bstats, u64_stats_read(&bstats.bytes),
u64_stats_read(&bstats.packets));
spin_unlock_bh(qdisc_lock(sch));
WRITE_ONCE(sch->qstats.qlen, qstats.qlen);
WRITE_ONCE(sch->qstats.backlog, qstats.backlog);
WRITE_ONCE(sch->qstats.drops, qstats.drops);
WRITE_ONCE(sch->qstats.requeues, qstats.requeues);
WRITE_ONCE(sch->qstats.overlimits, qstats.overlimits);
WRITE_ONCE(sch->q.qlen, qlen);
mqprio_qopt_reconstruct(dev, &opt);