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Thu, 20 Mar 2025 16:25:50 -0700 (PDT) Received: from pop-os.scu.edu ([129.210.115.104]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-7390611ccf8sm416306b3a.120.2025.03.20.16.25.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Mar 2025 16:25:50 -0700 (PDT) From: Cong Wang To: netdev@vger.kernel.org Cc: jhs@mojatatu.com, jiri@resnulli.us, edumazet@google.com, gerrard.tai@starlabs.sg, Cong Wang Subject: [Patch net 03/12] sch_hfsc: make hfsc_qlen_notify() idempotent Date: Thu, 20 Mar 2025 16:25:30 -0700 Message-Id: <20250320232539.486091-3-xiyou.wangcong@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250320232539.486091-1-xiyou.wangcong@gmail.com> References: <20250320232211.485785-1-xiyou.wangcong@gmail.com> <20250320232539.486091-1-xiyou.wangcong@gmail.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: kuba@kernel.org 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 --- net/sched/sch_hfsc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c index c287bf8423b4..ce5045eea065 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); }