7 files changed, 25 insertions, 23 deletions

diff --git a/net/sched/sch_api.c b/net/sched/sch_api.c
index c5e3673aadbe..d8a33486c511 100644
--- a/net/sched/sch_api.c
+++ b/net/sched/sch_api.c
@@ -780,15 +780,12 @@ 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)) {
@@ -797,17 +794,8 @@ 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) {
@@ -816,6 +804,9 @@ 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);
 		}
diff --git a/net/sched/sch_ets.c b/net/sched/sch_ets.c
index 2c069f0181c6..037f764822b9 100644
--- a/net/sched/sch_ets.c
+++ b/net/sched/sch_ets.c
@@ -661,7 +661,7 @@ static int ets_qdisc_change(struct Qdisc *sch, struct nlattr *opt,
 	for (i = q->nbands; i < oldbands; i++) {
 		if (i >= q->nstrict && q->classes[i].qdisc->q.qlen)
 			list_del_init(&q->classes[i].alist);
-		qdisc_tree_flush_backlog(q->classes[i].qdisc);
+		qdisc_purge_queue(q->classes[i].qdisc);
 	}
 	WRITE_ONCE(q->nstrict, nstrict);
 	memcpy(q->prio2band, priomap, sizeof(priomap));
diff --git a/net/sched/sch_prio.c b/net/sched/sch_prio.c
index cc30f7a32f1a..9e2b9a490db2 100644
--- a/net/sched/sch_prio.c
+++ b/net/sched/sch_prio.c
@@ -211,7 +211,7 @@ static int prio_tune(struct Qdisc *sch, struct nlattr *opt,
 	memcpy(q->prio2band, qopt->priomap, TC_PRIO_MAX+1);
 
 	for (i = q->bands; i < oldbands; i++)
-		qdisc_tree_flush_backlog(q->queues[i]);
+		qdisc_purge_queue(q->queues[i]);
 
 	for (i = oldbands; i < q->bands; i++) {
 		q->queues[i] = queues[i];
diff --git a/net/sched/sch_red.c b/net/sched/sch_red.c
index 339d70b4a4c5..479c42d11083 100644
--- a/net/sched/sch_red.c
+++ b/net/sched/sch_red.c
@@ -285,7 +285,7 @@ static int __red_change(struct Qdisc *sch, struct nlattr **tb,
 	q->userbits = userbits;
 	q->limit = ctl->limit;
 	if (child) {
-		qdisc_tree_flush_backlog(q->qdisc);
+		qdisc_purge_queue(q->qdisc);
 		old_child = q->qdisc;
 		q->qdisc = child;
 	}
diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index a8081492d671..96eb2f122973 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -310,7 +310,10 @@ drop:
 		/* It is difficult to believe, but ALL THE SLOTS HAVE LENGTH 1. */
 		x = q->tail->next;
 		slot = &q->slots[x];
-		q->tail->next = slot->next;
+		if (slot->next == x)
+			q->tail = NULL; /* no more active slots */
+		else
+			q->tail->next = slot->next;
 		q->ht[slot->hash] = SFQ_EMPTY_SLOT;
 		goto drop;
 	}
@@ -653,6 +656,14 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt,
 		NL_SET_ERR_MSG_MOD(extack, "invalid quantum");
 		return -EINVAL;
 	}
+
+	if (ctl->perturb_period < 0 ||
+	    ctl->perturb_period > INT_MAX / HZ) {
+		NL_SET_ERR_MSG_MOD(extack, "invalid perturb period");
+		return -EINVAL;
+	}
+	perturb_period = ctl->perturb_period * HZ;
+
 	if (ctl_v1 && !red_check_params(ctl_v1->qth_min, ctl_v1->qth_max,
 					ctl_v1->Wlog, ctl_v1->Scell_log, NULL))
 		return -EINVAL;
@@ -669,14 +680,12 @@ static int sfq_change(struct Qdisc *sch, struct nlattr *opt,
 	headdrop = q->headdrop;
 	maxdepth = q->maxdepth;
 	maxflows = q->maxflows;
-	perturb_period = q->perturb_period;
 	quantum = q->quantum;
 	flags = q->flags;
 
 	/* update and validate configuration */
 	if (ctl->quantum)
 		quantum = ctl->quantum;
-	perturb_period = ctl->perturb_period * HZ;
 	if (ctl->flows)
 		maxflows = min_t(u32, ctl->flows, SFQ_MAX_FLOWS);
 	if (ctl->divisor) {
diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 14021b812329..2b14c81a87e5 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1328,13 +1328,15 @@ static int taprio_dev_notifier(struct notifier_block *nb, unsigned long event,
 
 		stab = rtnl_dereference(q->root->stab);
 
-		oper = rtnl_dereference(q->oper_sched);
+		rcu_read_lock();
+		oper = rcu_dereference(q->oper_sched);
 		if (oper)
 			taprio_update_queue_max_sdu(q, oper, stab);
 
-		admin = rtnl_dereference(q->admin_sched);
+		admin = rcu_dereference(q->admin_sched);
 		if (admin)
 			taprio_update_queue_max_sdu(q, admin, stab);
+		rcu_read_unlock();
 
 		break;
 	}
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index dc26b22d53c7..4c977f049670 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -452,7 +452,7 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt,
 
 	sch_tree_lock(sch);
 	if (child) {
-		qdisc_tree_flush_backlog(q->qdisc);
+		qdisc_purge_queue(q->qdisc);
 		old = q->qdisc;
 		q->qdisc = child;
 	}