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

commit 342debc12183b51773b3345ba267e9263bdfaaef upstream.

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: 4b549a2ef4be ("fq_codel: Fair Queue Codel AQM")
Fixes: 76e3cc126bb2 ("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>
Signed-off-by: Siddh Raman Pant <siddh.raman.pant@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/sched/sch_codel.c b/net/sched/sch_codel.c
index d99c7386e24e6b66f3fbd66b57312e3da261e60a..0d4228bfd1a02fcd5c53a29ba35eb93b0d0f60d4 100644 (file)
--- a/net/sched/sch_codel.c
+++ b/net/sched/sch_codel.c
@@ -95,10 +95,7 @@ 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;

diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index 60dbc549e99103c2d47ce74fd4d892086a28c680..3c1efe360defad754fea47ea13fd7b83258f84c9 100644 (file)
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -314,10 +314,8 @@ 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) {
+
+       if (q->cstats.drop_count) {
                qdisc_tree_reduce_backlog(sch, q->cstats.drop_count,
                                          q->cstats.drop_len);
                q->cstats.drop_count = 0;