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: 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>

diff --git a/net/sched/sch_codel.c b/net/sched/sch_codel.c
index 81189d02fee761ad21142a205c347f33ef9a3edf..12dd71139da396f799298627655879dfb689538d 100644 (file)
--- a/net/sched/sch_codel.c
+++ b/net/sched/sch_codel.c
@@ -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;

diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index 799f5397ad4c17ba69ad64ea7abb058f6da3da9b..6c9029f71e88d3e348f537a42d345c82cee256a4 100644 (file)
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -315,10 +315,8 @@ 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;