From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Fri, 22 Jun 2018 14:33:16 -0700
Subject: net_sched: remove a bogus warning in hfsc
Patch-mainline: v4.18-rc3
Git-commit: 35b42da69e35536da603a50e40aa6c41b2f7b0f8
References: bsc#1109837

In update_vf():

  cftree_remove(cl);
  update_cfmin(cl->cl_parent);

the cl_cfmin of cl->cl_parent is intentionally updated to 0
when that parent only has one child. And if this parent is
root qdisc, we could end up, in hfsc_schedule_watchdog(),
that we can't decide the next schedule time for qdisc watchdog.
But it seems safe that we can just skip it, as this watchdog is
not always scheduled anyway.

Thanks to Marco for testing all the cases, nothing is broken.

Reported-by: Marco Berizzi <pupilla@libero.it>
Tested-by: Marco Berizzi <pupilla@libero.it>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/sched/sch_hfsc.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/net/sched/sch_hfsc.c
+++ b/net/sched/sch_hfsc.c
@@ -1385,8 +1385,8 @@ hfsc_schedule_watchdog(struct Qdisc *sch
 		if (next_time == 0 || next_time > q->root.cl_cfmin)
 			next_time = q->root.cl_cfmin;
 	}
-	WARN_ON(next_time == 0);
-	qdisc_watchdog_schedule(&q->watchdog, next_time);
+	if (next_time)
+		qdisc_watchdog_schedule(&q->watchdog, next_time);
 }
 
 static int