This makes a difference for the software scheduling mode, where
dev_queue->qdisc_sleeping is the same as the taprio root Qdisc itself,
but when we're talking about what Qdisc and stats get reported for a
traffic class, the root taprio isn't what comes to mind, but q->qdiscs[]
is.

To understand the difference, I've attempted to send 100 packets in
software mode through traffic class 0 (they are in the Qdisc's backlog),
and recorded the stats before and after the change.

Here is before:

$ tc -s class show dev eth0
class taprio 8001:1 root leaf 8001:
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 9400b 100p requeues 0
 Window drops: 0
class taprio 8001:2 root leaf 8001:
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 9400b 100p requeues 0
 Window drops: 0
class taprio 8001:3 root leaf 8001:
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 9400b 100p requeues 0
 Window drops: 0
class taprio 8001:4 root leaf 8001:
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 9400b 100p requeues 0
 Window drops: 0
class taprio 8001:5 root leaf 8001:
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 9400b 100p requeues 0
 Window drops: 0
class taprio 8001:6 root leaf 8001:
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 9400b 100p requeues 0
 Window drops: 0
class taprio 8001:7 root leaf 8001:
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 9400b 100p requeues 0
 Window drops: 0
class taprio 8001:8 root leaf 8001:
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 9400b 100p requeues 0
 Window drops: 0

and here is after:

class taprio 8001:1 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 9400b 100p requeues 0
 Window drops: 0
class taprio 8001:2 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 Window drops: 0
class taprio 8001:3 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 Window drops: 0
class taprio 8001:4 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 Window drops: 0
class taprio 8001:5 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 Window drops: 0
class taprio 8001:6 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 Window drops: 0
class taprio 8001:7 root leaf 8010:
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 Window drops: 0
class taprio 8001:8 root
 Sent 0 bytes 0 pkt (dropped 0, overlimits 0 requeues 0)
 backlog 0b 0p requeues 0
 Window drops: 0

The most glaring (and expected) difference is that before, all class
stats reported the global stats, whereas now, they really report just
the counters for that traffic class.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
 net/sched/sch_taprio.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index cc7ff98e5e86..23b98c3af8b2 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -2452,11 +2452,11 @@ static unsigned long taprio_find(struct Qdisc *sch, u32 classid)
 static int taprio_dump_class(struct Qdisc *sch, unsigned long cl,
 			     struct sk_buff *skb, struct tcmsg *tcm)
 {
-	struct netdev_queue *dev_queue = taprio_queue_get(sch, cl);
+	struct Qdisc *child = taprio_leaf(sch, cl);
 
 	tcm->tcm_parent = TC_H_ROOT;
 	tcm->tcm_handle |= TC_H_MIN(cl);
-	tcm->tcm_info = dev_queue->qdisc_sleeping->handle;
+	tcm->tcm_info = child->handle;
 
 	return 0;
 }
@@ -2466,8 +2466,7 @@ static int taprio_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 	__releases(d->lock)
 	__acquires(d->lock)
 {
-	struct netdev_queue *dev_queue = taprio_queue_get(sch, cl);
-	struct Qdisc *child = dev_queue->qdisc_sleeping;
+	struct Qdisc *child = taprio_leaf(sch, cl);
 	struct tc_taprio_qopt_offload offload = {
 		.cmd = TAPRIO_CMD_TC_STATS,
 		.tc_stats = {
-- 
2.34.1