net: sched: mq: request stats from offloads

MQ doesn't hold any statistics on its own, however, statistic
from offloads are requested starting from the root, hence MQ
will read the old values for its sums.  Call into the drivers,
because of the additive nature of the stats drivers are aware
of how much "pending updates" they have to children of the MQ.
Since MQ reset its stats on every dump we can simply offset
the stats, predicting how stats of offloaded children will
change.
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/pkt_cls.h

@@ -781,11 +781,13 @@ struct tc_qopt_offload_stats {
 enum tc_mq_command {
 	TC_MQ_CREATE,
 	TC_MQ_DESTROY,
+	TC_MQ_STATS,
 };
 
 struct tc_mq_qopt_offload {
 	enum tc_mq_command command;
 	u32 handle;
+	struct tc_qopt_offload_stats stats;
 };
 
 enum tc_red_command {

net/sched/sch_mq.c

@@ -38,6 +38,22 @@ static int mq_offload(struct Qdisc *sch, enum tc_mq_command cmd)
 	return dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_MQ, &opt);
 }
 
+static void mq_offload_stats(struct Qdisc *sch)
+{
+	struct net_device *dev = qdisc_dev(sch);
+	struct tc_mq_qopt_offload opt = {
+		.command = TC_MQ_STATS,
+		.handle = sch->handle,
+		.stats = {
+			.bstats = &sch->bstats,
+			.qstats = &sch->qstats,
+		},
+	};
+
+	if (tc_can_offload(dev) && dev->netdev_ops->ndo_setup_tc)
+		dev->netdev_ops->ndo_setup_tc(dev, TC_SETUP_QDISC_MQ, &opt);
+}
+
 static void mq_destroy(struct Qdisc *sch)
 {
 	struct net_device *dev = qdisc_dev(sch);
@@ -146,6 +162,7 @@ static int mq_dump(struct Qdisc *sch, struct sk_buff *skb)
 			sch->q.qlen		+= qdisc->q.qlen;
 			sch->bstats.bytes	+= qdisc->bstats.bytes;
 			sch->bstats.packets	+= qdisc->bstats.packets;
+			sch->qstats.qlen	+= qdisc->qstats.qlen;
 			sch->qstats.backlog	+= qdisc->qstats.backlog;
 			sch->qstats.drops	+= qdisc->qstats.drops;
 			sch->qstats.requeues	+= qdisc->qstats.requeues;
@@ -154,6 +171,7 @@ static int mq_dump(struct Qdisc *sch, struct sk_buff *skb)
 
 		spin_unlock_bh(qdisc_lock(qdisc));
 	}
+	mq_offload_stats(sch);
 
 	return 0;
 }