Commit df008598 authored by Cong Wang's avatar Cong Wang Committed by Paolo Abeni
Browse files

sch_drr: make drr_qlen_notify() idempotent 



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: default avatarGerrard Tai <gerrard.tai@starlabs.sg>
Signed-off-by: default avatarCong Wang <xiyou.wangcong@gmail.com>
Reviewed-by: default avatarSimon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250403211033.166059-3-xiyou.wangcong@gmail.com


Acked-by: default avatarJamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: default avatarPaolo Abeni <pabeni@redhat.com>
parent 5ba8b837

net/sched/sch_drr.c

+4 −3
Original line number Diff line number Diff line
@@ -105,6 +105,7 @@ static int drr_change_class(struct Qdisc *sch, u32 classid, u32 parentid, 
		return -ENOBUFS;



	gnet_stats_basic_sync_init(&cl->bstats);

	INIT_LIST_HEAD(&cl->alist);

	cl->common.classid = classid;

	cl->quantum	   = quantum;

	cl->qdisc	   = qdisc_create_dflt(sch->dev_queue,
@@ -229,7 +230,7 @@ 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,
@@ -390,7 +391,7 @@ 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);
@@ -431,7 +432,7 @@ 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);

		}

	}