4 files changed, 23 insertions, 14 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index f43c8f3..7ec667d 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -253,7 +253,8 @@ int qdisc_set_default(const char *name)
 }
 
 /* We know handle. Find qdisc among all qdisc's attached to device
-   (root qdisc, all its children, children of children etc.)
+ * (root qdisc, all its children, children of children etc.)
+ * Note: caller either uses rtnl or rcu_read_lock()
  */
 
 static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
@@ -264,7 +265,7 @@ static struct Qdisc *qdisc_match_from_root(struct Qdisc *root, u32 handle)
 	    root->handle == handle)
 		return root;
 
-	list_for_each_entry(q, &root->list, list) {
+	list_for_each_entry_rcu(q, &root->list, list) {
 		if (q->handle == handle)
 			return q;
 	}
@@ -277,15 +278,18 @@ void qdisc_list_add(struct Qdisc *q)
 		struct Qdisc *root = qdisc_dev(q)->qdisc;
 
 		WARN_ON_ONCE(root == &noop_qdisc);
-		list_add_tail(&q->list, &root->list);
+		ASSERT_RTNL();
+		list_add_tail_rcu(&q->list, &root->list);
 	}
 }
 EXPORT_SYMBOL(qdisc_list_add);
 
 void qdisc_list_del(struct Qdisc *q)
 {
-	if ((q->parent != TC_H_ROOT) && !(q->flags & TCQ_F_INGRESS))
-		list_del(&q->list);
+	if ((q->parent != TC_H_ROOT) && !(q->flags & TCQ_F_INGRESS)) {
+		ASSERT_RTNL();
+		list_del_rcu(&q->list);
+	}
 }
 EXPORT_SYMBOL(qdisc_list_del);
 
@@ -750,14 +754,18 @@ void qdisc_tree_decrease_qlen(struct Qdisc *sch, unsigned int n)
 	if (n == 0)
 		return;
 	drops = max_t(int, n, 0);
+	rcu_read_lock();
 	while ((parentid = sch->parent)) {
 		if (TC_H_MAJ(parentid) == TC_H_MAJ(TC_H_INGRESS))
-			return;
+			break;
 
+		if (sch->flags & TCQ_F_NOPARENT)
+			break;
+		/* TODO: perform the search on a per txq basis */
 		sch = qdisc_lookup(qdisc_dev(sch), TC_H_MAJ(parentid));
 		if (sch == NULL) {
-			WARN_ON(parentid != TC_H_ROOT);
-			return;
+			WARN_ON_ONCE(parentid != TC_H_ROOT);
+			break;
 		}
 		cops = sch->ops->cl_ops;
 		if (cops->qlen_notify) {
@@ -768,6 +776,7 @@ void qdisc_tree_decrease_qlen(struct Qdisc *sch, unsigned int n)
 		sch->q.qlen -= n;
 		__qdisc_qstats_drop(sch, drops);
 	}
+	rcu_read_unlock();
 }
 EXPORT_SYMBOL(qdisc_tree_decrease_qlen);
 
@@ -941,7 +950,7 @@ qdisc_create(struct net_device *dev, struct netdev_queue *dev_queue,
 		}
 		lockdep_set_class(qdisc_lock(sch), &qdisc_tx_lock);
 		if (!netif_is_multiqueue(dev))
-			sch->flags |= TCQ_F_ONETXQUEUE;
+			sch->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
 	}
 
 	sch->handle = handle;
diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index cb5d4ad..e82a1ad 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -737,7 +737,7 @@ static void attach_one_default_qdisc(struct net_device *dev,
 		return;
 	}
 	if (!netif_is_multiqueue(dev))
-		qdisc->flags |= TCQ_F_ONETXQUEUE;
+		qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
 	dev_queue->qdisc_sleeping = qdisc;
 }
 
diff --git a/net/sched/sch_mq.c b/net/sched/sch_mq.c
index f3cbaec..3e82f04 100644
--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -63,7 +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;
+		qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
 	}
 
 	sch->flags |= TCQ_F_MQROOT;
@@ -156,7 +156,7 @@ static int mq_graft(struct Qdisc *sch, unsigned long cl, struct Qdisc *new,
 
 	*old = dev_graft_qdisc(dev_queue, new);
 	if (new)
-		new->flags |= TCQ_F_ONETXQUEUE;
+		new->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
 	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 3811a74..ad70ecf 100644
--- a/net/sched/sch_mqprio.c
+++ b/net/sched/sch_mqprio.c
@@ -132,7 +132,7 @@ static int mqprio_init(struct Qdisc *sch, struct nlattr *opt)
 			goto err;
 		}
 		priv->qdiscs[i] = qdisc;
-		qdisc->flags |= TCQ_F_ONETXQUEUE;
+		qdisc->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
 	}
 
 	/* If the mqprio options indicate that hardware should own
@@ -209,7 +209,7 @@ 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;
+		new->flags |= TCQ_F_ONETXQUEUE | TCQ_F_NOPARENT;
 
 	if (dev->flags & IFF_UP)
 		dev_activate(dev);