Prepare mqprio_dump() for RTNL avoidance. Use RCU instead of RTNL, and no longer acquire each children spinlock. Signed-off-by: Eric Dumazet --- net/sched/sch_mqprio.c | 37 ++++++++++++++++++++++++------------- 1 file changed, 24 insertions(+), 13 deletions(-) diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c index 3b4881c389c535368687454ea268bec892ecb942..f9dab76f40ebbd1363121198bbc3af2bd951c101 100644 --- a/net/sched/sch_mqprio.c +++ b/net/sched/sch_mqprio.c @@ -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); -- 2.54.0.563.g4f69b47b94-goog