From: Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com>
Date: Mon, 16 Oct 2017 18:01:24 -0700
Subject: net/sched: Change behavior of mq select_queue()
Patch-mainline: v4.15-rc1
Git-commit: ce8a75f60b75831947569229616cf1bc94f2d965
References: bsc#1109837

Currently, the class_ops select_queue() implementation on sch_mq
returns a pointer to netdev_queue #0 when it receives and invalid
qdisc id. That can be misleading since all of mq's inner qdiscs are
attached to a valid netdev_queue.

Here we fix that by returning NULL when a qdisc id is invalid. This is
aligned with how select_queue() is implemented for sch_mqprio in the
next patch on this series, keeping a consistent behavior between these
two qdiscs.

Signed-off-by: Jesus Sanchez-Palencia <jesus.sanchez-palencia@intel.com>
Tested-by: Henrik Austad <henrik@austad.us>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/sched/sch_mq.c |   10 +---------
 1 file changed, 1 insertion(+), 9 deletions(-)

--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -130,15 +130,7 @@ static struct netdev_queue *mq_queue_get
 static struct netdev_queue *mq_select_queue(struct Qdisc *sch,
 					    struct tcmsg *tcm)
 {
-	unsigned int ntx = TC_H_MIN(tcm->tcm_parent);
-	struct netdev_queue *dev_queue = mq_queue_get(sch, ntx);
-
-	if (!dev_queue) {
-		struct net_device *dev = qdisc_dev(sch);
-
-		return netdev_get_tx_queue(dev, 0);
-	}
-	return dev_queue;
+	return mq_queue_get(sch, TC_H_MIN(tcm->tcm_parent));
 }
 
 static int mq_graft(struct Qdisc *sch, unsigned long cl, struct Qdisc *new,