1 files changed, 21 insertions, 21 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index 518f52f65a49..c56a01992cb2 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -334,17 +334,22 @@ out:
 	return q;
 }
 
-static struct Qdisc *qdisc_leaf(struct Qdisc *p, u32 classid)
+static struct Qdisc *qdisc_leaf(struct Qdisc *p, u32 classid,
+				struct netlink_ext_ack *extack)
 {
 	unsigned long cl;
 	const struct Qdisc_class_ops *cops = p->ops->cl_ops;
 
-	if (cops == NULL)
-		return NULL;
+	if (cops == NULL) {
+		NL_SET_ERR_MSG(extack, "Parent qdisc is not classful");
+		return ERR_PTR(-EOPNOTSUPP);
+	}
 	cl = cops->find(p, classid);
 
-	if (cl == 0)
-		return NULL;
+	if (cl == 0) {
+		NL_SET_ERR_MSG(extack, "Specified class not found");
+		return ERR_PTR(-ENOENT);
+	}
 	return cops->leaf(p, cl);
 }
 
@@ -779,15 +784,12 @@ static u32 qdisc_alloc_handle(struct net_device *dev)
 
 void qdisc_tree_reduce_backlog(struct Qdisc *sch, int n, int len)
 {
-	bool qdisc_is_offloaded = sch->flags & TCQ_F_OFFLOADED;
 	const struct Qdisc_class_ops *cops;
 	unsigned long cl;
 	u32 parentid;
 	bool notify;
 	int drops;
 
-	if (n == 0 && len == 0)
-		return;
 	drops = max_t(int, n, 0);
 	rcu_read_lock();
 	while ((parentid = sch->parent)) {
@@ -796,17 +798,8 @@ void qdisc_tree_reduce_backlog(struct Qdisc *sch, int n, int len)
 
 		if (sch->flags & TCQ_F_NOPARENT)
 			break;
-		/* Notify parent qdisc only if child qdisc becomes empty.
-		 *
-		 * 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 &&
-						       !qdisc_is_offloaded);
+		/* Notify parent qdisc only if child qdisc becomes empty. */
+		notify = !sch->q.qlen;
 		/* TODO: perform the search on a per txq basis */
 		sch = qdisc_lookup_rcu(qdisc_dev(sch), TC_H_MAJ(parentid));
 		if (sch == NULL) {
@@ -815,6 +808,9 @@ void qdisc_tree_reduce_backlog(struct Qdisc *sch, int n, int len)
 		}
 		cops = sch->ops->cl_ops;
 		if (notify && cops->qlen_notify) {
+			/* Note that qlen_notify must be idempotent as it may get called
+			 * multiple times.
+			 */
 			cl = cops->find(sch, parentid);
 			cops->qlen_notify(sch, cl);
 		}
@@ -1535,7 +1531,7 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
 					NL_SET_ERR_MSG(extack, "Failed to find qdisc with specified classid");
 					return -ENOENT;
 				}
-				q = qdisc_leaf(p, clid);
+				q = qdisc_leaf(p, clid, extack);
 			} else if (dev_ingress_queue(dev)) {
 				q = rtnl_dereference(dev_ingress_queue(dev)->qdisc_sleeping);
 			}
@@ -1546,6 +1542,8 @@ static int tc_get_qdisc(struct sk_buff *skb, struct nlmsghdr *n,
 			NL_SET_ERR_MSG(extack, "Cannot find specified qdisc on specified device");
 			return -ENOENT;
 		}
+		if (IS_ERR(q))
+			return PTR_ERR(q);
 
 		if (tcm->tcm_handle && q->handle != tcm->tcm_handle) {
 			NL_SET_ERR_MSG(extack, "Invalid handle");
@@ -1639,7 +1637,9 @@ replay:
 					NL_SET_ERR_MSG(extack, "Failed to find specified qdisc");
 					return -ENOENT;
 				}
-				q = qdisc_leaf(p, clid);
+				q = qdisc_leaf(p, clid, extack);
+				if (IS_ERR(q))
+					return PTR_ERR(q);
 			} else if (dev_ingress_queue_create(dev)) {
 				q = rtnl_dereference(dev_ingress_queue(dev)->qdisc_sleeping);
 			}