From: Cong Wang Date: Thu, 3 Apr 2025 21:10:25 +0000 (-0700) Subject: sch_hfsc: make hfsc_qlen_notify() idempotent X-Git-Tag: v6.15-rc2~22^2~18^2~8 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=51eb3b65544c9efd6a1026889ee5fb5aa62da3bb;p=thirdparty%2Flinux.git sch_hfsc: make hfsc_qlen_notify() idempotent hfsc_qlen_notify() is not idempotent either and not friendly to its callers, like fq_codel_dequeue(). Let's make it idempotent to ease qdisc_tree_reduce_backlog() callers' life: 1. update_vf() decreases cl->cl_nactive, so we can check whether it is non-zero before calling it. 2. eltree_remove() always removes RB node cl->el_node, but we can use RB_EMPTY_NODE() + RB_CLEAR_NODE() to make it safe. Reported-by: Gerrard Tai Signed-off-by: Cong Wang Reviewed-by: Simon Horman Link: https://patch.msgid.link/20250403211033.166059-4-xiyou.wangcong@gmail.com Acked-by: Jamal Hadi Salim Signed-off-by: Paolo Abeni --- diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c index c287bf8423b47..ce5045eea0656 100644 --- a/net/sched/sch_hfsc.c +++ b/net/sched/sch_hfsc.c @@ -203,7 +203,10 @@ eltree_insert(struct hfsc_class *cl) static inline void eltree_remove(struct hfsc_class *cl) { - rb_erase(&cl->el_node, &cl->sched->eligible); + if (!RB_EMPTY_NODE(&cl->el_node)) { + rb_erase(&cl->el_node, &cl->sched->eligible); + RB_CLEAR_NODE(&cl->el_node); + } } static inline void @@ -1220,7 +1223,8 @@ hfsc_qlen_notify(struct Qdisc *sch, unsigned long arg) /* vttree is now handled in update_vf() so that update_vf(cl, 0, 0) * needs to be called explicitly to remove a class from vttree. */ - update_vf(cl, 0, 0); + if (cl->cl_nactive) + update_vf(cl, 0, 0); if (cl->cl_flags & HFSC_RSC) eltree_remove(cl); }