mirror of
				git://git.openwrt.org/openwrt/openwrt.git
				synced 2025-11-03 14:34:27 -05:00 
			
		
		
		
	
		
			
				
	
	
		
			87 lines
		
	
	
		
			3.0 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
			
		
		
	
	
			87 lines
		
	
	
		
			3.0 KiB
		
	
	
	
		
			Diff
		
	
	
	
	
	
From: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
 | 
						|
Date: Mon, 21 Aug 2017 11:14:14 +0300
 | 
						|
Subject: [PATCH] net_sched/codel: do not defer queue length update
 | 
						|
 | 
						|
When codel wants to drop last packet in ->dequeue() it cannot call
 | 
						|
qdisc_tree_reduce_backlog() right away - it will notify parent qdisc
 | 
						|
about zero qlen and HTB/HFSC will deactivate class. The same class will
 | 
						|
be deactivated second time by caller of ->dequeue(). Currently codel and
 | 
						|
fq_codel defer update. This triggers warning in HFSC when it's qlen != 0
 | 
						|
but there is no active classes.
 | 
						|
 | 
						|
This patch update parent queue length immediately: just temporary increase
 | 
						|
qlen around qdisc_tree_reduce_backlog() to prevent first class deactivation
 | 
						|
if we have skb to return.
 | 
						|
 | 
						|
This might open another problem in HFSC - now operation peek could fail and
 | 
						|
deactivate parent class.
 | 
						|
 | 
						|
Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
 | 
						|
Link: https://bugzilla.kernel.org/show_bug.cgi?id=109581
 | 
						|
---
 | 
						|
 | 
						|
--- a/net/sched/sch_codel.c
 | 
						|
+++ b/net/sched/sch_codel.c
 | 
						|
@@ -95,11 +95,17 @@ static struct sk_buff *codel_qdisc_deque
 | 
						|
 			    &q->stats, qdisc_pkt_len, codel_get_enqueue_time,
 | 
						|
 			    drop_func, dequeue_func);
 | 
						|
 
 | 
						|
-	/* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
 | 
						|
-	 * or HTB crashes. Defer it for next round.
 | 
						|
+	/* If our qlen is 0 qdisc_tree_reduce_backlog() will deactivate
 | 
						|
+	 * parent class, dequeue in parent qdisc will do the same if we
 | 
						|
+	 * return skb. Temporary increment qlen if we have skb.
 | 
						|
 	 */
 | 
						|
-	if (q->stats.drop_count && sch->q.qlen) {
 | 
						|
-		qdisc_tree_reduce_backlog(sch, q->stats.drop_count, q->stats.drop_len);
 | 
						|
+	if (q->stats.drop_count) {
 | 
						|
+		if (skb)
 | 
						|
+			sch->q.qlen++;
 | 
						|
+		qdisc_tree_reduce_backlog(sch, q->stats.drop_count,
 | 
						|
+					  q->stats.drop_len);
 | 
						|
+		if (skb)
 | 
						|
+			sch->q.qlen--;
 | 
						|
 		q->stats.drop_count = 0;
 | 
						|
 		q->stats.drop_len = 0;
 | 
						|
 	}
 | 
						|
--- a/net/sched/sch_fq_codel.c
 | 
						|
+++ b/net/sched/sch_fq_codel.c
 | 
						|
@@ -304,6 +304,21 @@ begin:
 | 
						|
 			    &flow->cvars, &q->cstats, qdisc_pkt_len,
 | 
						|
 			    codel_get_enqueue_time, drop_func, dequeue_func);
 | 
						|
 
 | 
						|
+	/* If our qlen is 0 qdisc_tree_reduce_backlog() will deactivate
 | 
						|
+	 * parent class, dequeue in parent qdisc will do the same if we
 | 
						|
+	 * return skb. Temporary increment qlen if we have skb.
 | 
						|
+	 */
 | 
						|
+	if (q->cstats.drop_count) {
 | 
						|
+		if (skb)
 | 
						|
+			sch->q.qlen++;
 | 
						|
+		qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
 | 
						|
+					  q->cstats.drop_len);
 | 
						|
+		if (skb)
 | 
						|
+			sch->q.qlen--;
 | 
						|
+		q->cstats.drop_count = 0;
 | 
						|
+		q->cstats.drop_len = 0;
 | 
						|
+	}
 | 
						|
+
 | 
						|
 	if (!skb) {
 | 
						|
 		/* force a pass through old_flows to prevent starvation */
 | 
						|
 		if ((head == &q->new_flows) && !list_empty(&q->old_flows))
 | 
						|
@@ -314,15 +329,6 @@ begin:
 | 
						|
 	}
 | 
						|
 	qdisc_bstats_update(sch, skb);
 | 
						|
 	flow->deficit -= qdisc_pkt_len(skb);
 | 
						|
-	/* We cant call qdisc_tree_reduce_backlog() if our qlen is 0,
 | 
						|
-	 * or HTB crashes. Defer it for next round.
 | 
						|
-	 */
 | 
						|
-	if (q->cstats.drop_count && sch->q.qlen) {
 | 
						|
-		qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
 | 
						|
-					  q->cstats.drop_len);
 | 
						|
-		q->cstats.drop_count = 0;
 | 
						|
-		q->cstats.drop_len = 0;
 | 
						|
-	}
 | 
						|
 	return skb;
 | 
						|
 }
 | 
						|
 
 |