Commit 342debc1 authored Apr 03, 2025 by Cong Wang Committed by Paolo Abeni Apr 08, 2025

codel: remove sch->q.qlen check before qdisc_tree_reduce_backlog()



After making all ->qlen_notify() callbacks idempotent, now it is safe to
remove the check of qlen!=0 from both fq_codel_dequeue() and
codel_qdisc_dequeue().

Reported-by: Gerrard Tai <gerrard.tai@starlabs.sg>
Fixes: 4b549a2e ("fq_codel: Fair Queue Codel AQM")
Fixes: 76e3cc12 ("codel: Controlled Delay AQM")
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250403211636.166257-1-xiyou.wangcong@gmail.com


Acked-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

parent a7a15f39

net/sched/sch_codel.c

+1 −4

Original line number	Diff line number	Diff line
		@@ -65,10 +65,7 @@ static struct sk_buff codel_qdisc_dequeue(struct Qdisc sch)
		&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 (q->stats.drop_count && sch->q.qlen) {
		if (q->stats.drop_count) {
		qdisc_tree_reduce_backlog(sch, q->stats.drop_count, q->stats.drop_len);
		q->stats.drop_count = 0;
		q->stats.drop_len = 0;

net/sched/sch_fq_codel.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -315,10 +315,8 @@ static struct sk_buff fq_codel_dequeue(struct Qdisc sch)
		}
		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) {

		if (q->cstats.drop_count) {
		qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
		q->cstats.drop_len);
		q->cstats.drop_count = 0;