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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Dust Li <dust.li@linux.alibaba.com>,
        Tony Lu <tonylu@linux.alibaba.com>,
        Cong Wang <xiyou.wangcong@gmail.com>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.4 89/92] net: sched: fix `tc -s class show` no bstats on class with nolock subqueues
Date:   Wed,  4 Dec 2019 18:50:29 +0100
Message-Id: <20191204174335.511244512@linuxfoundation.org>
In-Reply-To: <20191204174327.215426506@linuxfoundation.org>
References: <20191204174327.215426506@linuxfoundation.org>
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From: Dust Li <dust.li@linux.alibaba.com>

[ Upstream commit 14e54ab9143fa60794d13ea0a66c792a2046a8f3 ]

When a classful qdisc's child qdisc has set the flag
TCQ_F_CPUSTATS (pfifo_fast for example), the child qdisc's
cpu_bstats should be passed to gnet_stats_copy_basic(),
but many classful qdisc didn't do that. As a result,
`tc -s class show dev DEV` always return 0 for bytes and
packets in this case.

Pass the child qdisc's cpu_bstats to gnet_stats_copy_basic()
to fix this issue.

The qstats also has this problem, but it has been fixed
in 5dd431b6b9 ("net: sched: introduce and use qstats read...")
and bstats still remains buggy.

Fixes: 22e0f8b9322c ("net: sched: make bstats per cpu and estimator RCU safe")
Signed-off-by: Dust Li <dust.li@linux.alibaba.com>
Signed-off-by: Tony Lu <tonylu@linux.alibaba.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/sched/sch_mq.c     |    2 +-
 net/sched/sch_mqprio.c |    3 ++-
 net/sched/sch_multiq.c |    2 +-
 net/sched/sch_prio.c   |    2 +-
 4 files changed, 5 insertions(+), 4 deletions(-)

--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -195,7 +195,7 @@ static int mq_dump_class_stats(struct Qd
 	struct netdev_queue *dev_queue = mq_queue_get(sch, cl);
 
 	sch = dev_queue->qdisc_sleeping;
-	if (gnet_stats_copy_basic(d, NULL, &sch->bstats) < 0 ||
+	if (gnet_stats_copy_basic(d, sch->cpu_bstats, &sch->bstats) < 0 ||
 	    gnet_stats_copy_queue(d, NULL, &sch->qstats, sch->q.qlen) < 0)
 		return -1;
 	return 0;
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -355,7 +355,8 @@ static int mqprio_dump_class_stats(struc
 		struct netdev_queue *dev_queue = mqprio_queue_get(sch, cl);
 
 		sch = dev_queue->qdisc_sleeping;
-		if (gnet_stats_copy_basic(d, NULL, &sch->bstats) < 0 ||
+		if (gnet_stats_copy_basic(d, sch->cpu_bstats,
+					  &sch->bstats) < 0 ||
 		    gnet_stats_copy_queue(d, NULL,
 					  &sch->qstats, sch->q.qlen) < 0)
 			return -1;
--- a/net/sched/sch_multiq.c
+++ b/net/sched/sch_multiq.c
@@ -351,7 +351,7 @@ static int multiq_dump_class_stats(struc
 	struct Qdisc *cl_q;
 
 	cl_q = q->queues[cl - 1];
-	if (gnet_stats_copy_basic(d, NULL, &cl_q->bstats) < 0 ||
+	if (gnet_stats_copy_basic(d, cl_q->cpu_bstats, &cl_q->bstats) < 0 ||
 	    gnet_stats_copy_queue(d, NULL, &cl_q->qstats, cl_q->q.qlen) < 0)
 		return -1;
 
--- a/net/sched/sch_prio.c
+++ b/net/sched/sch_prio.c
@@ -319,7 +319,7 @@ static int prio_dump_class_stats(struct
 	struct Qdisc *cl_q;
 
 	cl_q = q->queues[cl - 1];
-	if (gnet_stats_copy_basic(d, NULL, &cl_q->bstats) < 0 ||
+	if (gnet_stats_copy_basic(d, cl_q->cpu_bstats, &cl_q->bstats) < 0 ||
 	    gnet_stats_copy_queue(d, NULL, &cl_q->qstats, cl_q->q.qlen) < 0)
 		return -1;