From fcf09d75c308c10dde799c9492735436d1d0245d Mon Sep 17 00:00:00 2001 From: Cong Wang Date: Thu, 3 Apr 2025 14:10:24 -0700 Subject: [PATCH] sch_drr: make drr_qlen_notify() idempotent commit df008598b3a00be02a8051fde89ca0fbc416bd55 upstream. drr_qlen_notify() always deletes the DRR class from its active list with list_del(), therefore, it is not idempotent and not friendly to its callers, like fq_codel_dequeue(). Let's make it idempotent to ease qdisc_tree_reduce_backlog() callers' life. Also change other list_del()'s to list_del_init() just to be extra safe. Reported-by: Gerrard Tai Signed-off-by: Cong Wang Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250403211033.166059-3-xiyou.wangcong@gmail.com Acked-by: Jamal Hadi Salim Signed-off-by: Paolo Abeni Signed-off-by: Siddh Raman Pant Signed-off-by: Greg Kroah-Hartman --- net/sched/sch_drr.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/sched/sch_drr.c b/net/sched/sch_drr.c index 1a0571806342..088084eb393e 100644 --- a/net/sched/sch_drr.c +++ b/net/sched/sch_drr.c @@ -111,6 +111,7 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid, if (cl == NULL) return -ENOBUFS; + INIT_LIST_HEAD(&cl->alist); cl->common.classid = classid; cl->quantum = quantum; cl->qdisc = qdisc_create_dflt(sch->dev_queue, @@ -234,7 +235,7 @@ static void drr_qlen_notify(struct Qdisc *csh, unsigned long arg) { struct drr_class *cl = (struct drr_class *)arg; - list_del(&cl->alist); + list_del_init(&cl->alist); } static int drr_dump_class(struct Qdisc *sch, unsigned long arg, @@ -401,7 +402,7 @@ static struct sk_buff *drr_dequeue(struct Qdisc *sch) if (unlikely(skb == NULL)) goto out; if (cl->qdisc->q.qlen == 0) - list_del(&cl->alist); + list_del_init(&cl->alist); bstats_update(&cl->bstats, skb); qdisc_bstats_update(sch, skb); @@ -442,7 +443,7 @@ static void drr_reset_qdisc(struct Qdisc *sch) for (i = 0; i < q->clhash.hashsize; i++) { hlist_for_each_entry(cl, &q->clhash.hash[i], common.hnode) { if (cl->qdisc->q.qlen) - list_del(&cl->alist); + list_del_init(&cl->alist); qdisc_reset(cl->qdisc); } }