1 files changed, 23 insertions, 28 deletions

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 8c64a552a64f..3b0f62095803 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -304,8 +304,8 @@ trace:
 
 /*
  * Transmit possibly several skbs, and handle the return status as
- * required. Owning running seqcount bit guarantees that
- * only one CPU can execute this function.
+ * required. Owning qdisc running bit guarantees that only one CPU
+ * can execute this function.
  *
  * Returns to the caller:
  *				false  - hardware queue frozen backoff
@@ -606,7 +606,6 @@ struct Qdisc noop_qdisc = {
 	.ops		=	&noop_qdisc_ops,
 	.q.lock		=	__SPIN_LOCK_UNLOCKED(noop_qdisc.q.lock),
 	.dev_queue	=	&noop_netdev_queue,
-	.running	=	SEQCNT_ZERO(noop_qdisc.running),
 	.busylock	=	__SPIN_LOCK_UNLOCKED(noop_qdisc.busylock),
 	.gso_skb = {
 		.next = (struct sk_buff *)&noop_qdisc.gso_skb,
@@ -867,7 +866,6 @@ struct Qdisc_ops pfifo_fast_ops __read_mostly = {
 EXPORT_SYMBOL(pfifo_fast_ops);
 
 static struct lock_class_key qdisc_tx_busylock;
-static struct lock_class_key qdisc_running_key;
 
 struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 			  const struct Qdisc_ops *ops,
@@ -892,11 +890,12 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 	__skb_queue_head_init(&sch->gso_skb);
 	__skb_queue_head_init(&sch->skb_bad_txq);
 	qdisc_skb_head_init(&sch->q);
+	gnet_stats_basic_sync_init(&sch->bstats);
 	spin_lock_init(&sch->q.lock);
 
 	if (ops->static_flags & TCQ_F_CPUSTATS) {
 		sch->cpu_bstats =
-			netdev_alloc_pcpu_stats(struct gnet_stats_basic_cpu);
+			netdev_alloc_pcpu_stats(struct gnet_stats_basic_sync);
 		if (!sch->cpu_bstats)
 			goto errout1;
 
@@ -916,10 +915,6 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 	lockdep_set_class(&sch->seqlock,
 			  dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 
-	seqcount_init(&sch->running);
-	lockdep_set_class(&sch->running,
-			  dev->qdisc_running_key ?: &qdisc_running_key);
-
 	sch->ops = ops;
 	sch->flags = ops->static_flags;
 	sch->enqueue = ops->enqueue;
@@ -1492,10 +1487,6 @@ void psched_ppscfg_precompute(struct psched_pktrate *r, u64 pktrate64)
 }
 EXPORT_SYMBOL(psched_ppscfg_precompute);
 
-static void mini_qdisc_rcu_func(struct rcu_head *head)
-{
-}
-
 void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
 			  struct tcf_proto *tp_head)
 {
@@ -1508,28 +1499,30 @@ void mini_qdisc_pair_swap(struct mini_Qdisc_pair *miniqp,
 
 	if (!tp_head) {
 		RCU_INIT_POINTER(*miniqp->p_miniq, NULL);
-		/* Wait for flying RCU callback before it is freed. */
-		rcu_barrier();
-		return;
-	}
+	} else {
+		miniq = miniq_old != &miniqp->miniq1 ?
+			&miniqp->miniq1 : &miniqp->miniq2;
 
-	miniq = !miniq_old || miniq_old == &miniqp->miniq2 ?
-		&miniqp->miniq1 : &miniqp->miniq2;
+		/* We need to make sure that readers won't see the miniq
+		 * we are about to modify. So ensure that at least one RCU
+		 * grace period has elapsed since the miniq was made
+		 * inactive.
+		 */
+		if (IS_ENABLED(CONFIG_PREEMPT_RT))
+			cond_synchronize_rcu(miniq->rcu_state);
+		else if (!poll_state_synchronize_rcu(miniq->rcu_state))
+			synchronize_rcu_expedited();
 
-	/* We need to make sure that readers won't see the miniq
-	 * we are about to modify. So wait until previous call_rcu callback
-	 * is done.
-	 */
-	rcu_barrier();
-	miniq->filter_list = tp_head;
-	rcu_assign_pointer(*miniqp->p_miniq, miniq);
+		miniq->filter_list = tp_head;
+		rcu_assign_pointer(*miniqp->p_miniq, miniq);
+	}
 
 	if (miniq_old)
-		/* This is counterpart of the rcu barriers above. We need to
+		/* This is counterpart of the rcu sync above. We need to
 		 * block potential new user of miniq_old until all readers
 		 * are not seeing it.
 		 */
-		call_rcu(&miniq_old->rcu, mini_qdisc_rcu_func);
+		miniq_old->rcu_state = start_poll_synchronize_rcu();
 }
 EXPORT_SYMBOL(mini_qdisc_pair_swap);
 
@@ -1548,6 +1541,8 @@ void mini_qdisc_pair_init(struct mini_Qdisc_pair *miniqp, struct Qdisc *qdisc,
 	miniqp->miniq1.cpu_qstats = qdisc->cpu_qstats;
 	miniqp->miniq2.cpu_bstats = qdisc->cpu_bstats;
 	miniqp->miniq2.cpu_qstats = qdisc->cpu_qstats;
+	miniqp->miniq1.rcu_state = get_state_synchronize_rcu();
+	miniqp->miniq2.rcu_state = miniqp->miniq1.rcu_state;
 	miniqp->p_miniq = p_miniq;
 }
 EXPORT_SYMBOL(mini_qdisc_pair_init);