5 files changed, 22 insertions, 6 deletions

diff --git a/include/net/sch_generic.h b/include/net/sch_generic.h
index 4616f468d599..1540f9c2fcf4 100644
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -50,6 +50,13 @@ struct Qdisc {
 #define TCQ_F_INGRESS		2
 #define TCQ_F_CAN_BYPASS	4
 #define TCQ_F_MQROOT		8
+#define TCQ_F_ONETXQUEUE	0x10 /* dequeue_skb() can assume all skbs are for
+				      * q->dev_queue : It can test
+				      * netif_xmit_frozen_or_stopped() before
+				      * dequeueing next packet.
+				      * Its true for MQ/MQPRIO slaves, or non
+				      * multiqueue device.
+				      */
 #define TCQ_F_WARN_NONWC	(1 << 16)
 	int			padded;
 	const struct Qdisc_ops	*ops;
diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 4799c4840c1a..d84f7e734cd7 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -833,6 +833,8 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue,
 				goto err_out3;
 		}
 		lockdep_set_class(qdisc_lock(sch), &qdisc_tx_lock);
+		if (!netif_is_multiqueue(dev))
+			sch->flags |= TCQ_F_ONETXQUEUE;
 	}
 
 	sch->handle = handle;
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index aefc1504dc88..5d81a4478514 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -53,20 +53,19 @@ static inline int dev_requeue_skb(struct sk_buff *skb, struct Qdisc *q)
 static inline struct sk_buff *dequeue_skb(struct Qdisc *q)
 {
 	struct sk_buff *skb = q->gso_skb;
+	const struct netdev_queue *txq = q->dev_queue;
 
 	if (unlikely(skb)) {
-		struct net_device *dev = qdisc_dev(q);
-		struct netdev_queue *txq;
-
 		/* check the reason of requeuing without tx lock first */
-		txq = netdev_get_tx_queue(dev, skb_get_queue_mapping(skb));
+		txq = netdev_get_tx_queue(txq->dev, skb_get_queue_mapping(skb));
 		if (!netif_xmit_frozen_or_stopped(txq)) {
 			q->gso_skb = NULL;
 			q->q.qlen--;
 		} else
 			skb = NULL;
 	} else {
-		skb = q->dequeue(q);
+		if (!(q->flags & TCQ_F_ONETXQUEUE) || !netif_xmit_frozen_or_stopped(txq))
+			skb = q->dequeue(q);
 	}
 
 	return skb;
@@ -686,6 +685,8 @@ static void attach_one_default_qdisc(struct net_device *dev,
 			netdev_info(dev, "activation failed\n");
 			return;
 		}
+		if (!netif_is_multiqueue(dev))
+			qdisc->flags |= TCQ_F_ONETXQUEUE;
 	}
 	dev_queue->qdisc_sleeping = qdisc;
 }
diff --git a/net/sched/sch_mq.c b/net/sched/sch_mq.c
index 0a4b2f9a0094..5da78a19ac9a 100644
--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -63,6 +63,7 @@ static int mq_init(struct Qdisc *sch, struct nlattr *opt)
 		if (qdisc == NULL)
 			goto err;
 		priv->qdiscs[ntx] = qdisc;
+		qdisc->flags |= TCQ_F_ONETXQUEUE;
 	}
 
 	sch->flags |= TCQ_F_MQROOT;
@@ -150,7 +151,8 @@ static int mq_graft(struct Qdisc *sch, unsigned long cl, struct Qdisc *new,
 		dev_deactivate(dev);
 
 	*old = dev_graft_qdisc(dev_queue, new);
-
+	if (new)
+		new->flags |= TCQ_F_ONETXQUEUE;
 	if (dev->flags & IFF_UP)
 		dev_activate(dev);
 	return 0;
diff --git a/net/sched/sch_mqprio.c b/net/sched/sch_mqprio.c
index d1831ca966d4..accec33c454c 100644
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -132,6 +132,7 @@ static int mqprio_init(struct Qdisc *sch, struct nlattr *opt)
 			goto err;
 		}
 		priv->qdiscs[i] = qdisc;
+		qdisc->flags |= TCQ_F_ONETXQUEUE;
 	}
 
 	/* If the mqprio options indicate that hardware should own
@@ -205,6 +206,9 @@ static int mqprio_graft(struct Qdisc *sch, unsigned long cl, struct Qdisc *new,
 
 	*old = dev_graft_qdisc(dev_queue, new);
 
+	if (new)
+		new->flags |= TCQ_F_ONETXQUEUE;
+
 	if (dev->flags & IFF_UP)
 		dev_activate(dev);