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net/sched: mq: no longer acquire qdisc spinlocks in dump operations

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Prepare mq_dump_common() 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/20260510091455.4039245-7-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet
2026-05-10 09:14:53 +00:00
committed by Jakub Kicinski
parent 5b12bd5c47
commit 4f07179f40
2 changed files with 31 additions and 10 deletions
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9
include/net/sch_generic.h
View File

@@ -952,6 +952,15 @@ static inline void _bstats_update(struct gnet_stats_basic_sync *bstats,
u64_stats_update_end(&bstats->syncp);
}
static inline void _bstats_set(struct gnet_stats_basic_sync *bstats,
u64 bytes, u64 packets)
{
u64_stats_update_begin(&bstats->syncp);
u64_stats_set(&bstats->bytes, bytes);
u64_stats_set(&bstats->packets, packets);
u64_stats_update_end(&bstats->syncp);
}
static inline void bstats_update(struct gnet_stats_basic_sync *bstats,
const struct sk_buff *skb)
{

32
net/sched/sch_mq.c
View File

@@ -143,30 +143,42 @@ EXPORT_SYMBOL_NS_GPL(mq_attach, "NET_SCHED_INTERNAL");
void mq_dump_common(struct Qdisc *sch, struct sk_buff *skb)
{
struct net_device *dev = qdisc_dev(sch);
struct gnet_stats_queue qstats = { 0 };
struct gnet_stats_basic_sync bstats;
const struct Qdisc *qdisc;
unsigned int qlen = 0;
struct Qdisc *qdisc;
unsigned int ntx;
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);
}
EXPORT_SYMBOL_NS_GPL(mq_dump_common, "NET_SCHED_INTERNAL");