netdev - [patch net-next 06/10] net: sch: Don't warn on missmatching qlen and backlog for offloaded qdiscs

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Message-Id: <20180228094507.22354-7-jiri@resnulli.us>
Date:   Wed, 28 Feb 2018 10:45:03 +0100
From:   Jiri Pirko <jiri@...nulli.us>
To:     netdev@...r.kernel.org
Cc:     nogahf@...lanox.com, yuvalm@...lanox.com, davem@...emloft.net,
        idosch@...lanox.com, mlxsw@...lanox.com, jhs@...atatu.com,
        xiyou.wangcong@...il.com, kubakici@...pl
Subject: [patch net-next 06/10] net: sch: Don't warn on missmatching qlen and backlog for offloaded qdiscs

From: Nogah Frankel <nogahf@...lanox.com>

Offloaded qdiscs are allowed to expose only parts of their statistics.
It means that if backlog is being exposed and qlen is not, it might trigger
a warning in qdisc_tree_reduce_backlog.
Do not warn in case the qdisc that was removed was an offloaded one.

Signed-off-by: Nogah Frankel <nogahf@...lanox.com>
Reviewed-by: Yuval Mintz <yuvalm@...lanox.com>
Signed-off-by: Jiri Pirko <jiri@...lanox.com>
---
 net/sched/sch_api.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 27e672c12492..68f9d942bed4 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -739,6 +739,7 @@ static u32 qdisc_alloc_handle(struct net_device *dev)
 void qdisc_tree_reduce_backlog(struct Qdisc *sch, unsigned int n,
 			       unsigned int len)
 {
+	bool qdisc_is_offloaded = sch->flags & TCQ_F_OFFLOADED;
 	const struct Qdisc_class_ops *cops;
 	unsigned long cl;
 	u32 parentid;
@@ -760,8 +761,12 @@ void qdisc_tree_reduce_backlog(struct Qdisc *sch, unsigned int n,
 		 * If child was empty even before update then backlog
 		 * counter is screwed and we skip notification because
 		 * parent class is already passive.
+		 *
+		 * If the original child was offloaded then it is allowed
+		 * to be seem as empty, so the parent is notified anyway.
 		 */
-		notify = !sch->q.qlen && !WARN_ON_ONCE(!n);
+		notify = !sch->q.qlen && !WARN_ON_ONCE(!n &&
+						       !qdisc_is_offloaded);
 		/* TODO: perform the search on a per txq basis */
 		sch = qdisc_lookup(qdisc_dev(sch), TC_H_MAJ(parentid));
 		if (sch == NULL) {
-- 
2.14.3