5.4-stable review patch. If anyone has any objections, please let me know.
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From: Cong Wang xiyou.wangcong@gmail.com
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 gerrard.tai@starlabs.sg Signed-off-by: Cong Wang xiyou.wangcong@gmail.com Reviewed-by: Simon Horman horms@kernel.org Link: https://patch.msgid.link/20250403211033.166059-3-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 --- net/sched/sch_drr.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
--- a/net/sched/sch_drr.c +++ b/net/sched/sch_drr.c @@ -111,6 +111,7 @@ static int drr_change_class(struct Qdisc 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 { 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(struc 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 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); } }