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([2a0d:3344:246d:aa10::f39]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-441b2af2a9dsm85925535e9.19.2025.05.02.02.59.22 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 02 May 2025 02:59:23 -0700 (PDT) Message-ID: <74017437-48d2-4518-9888-e74c14e01a5d@redhat.com> Date: Fri, 2 May 2025 11:59:21 +0200 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [Patch net 1/2] sch_htb: make htb_deactivate() idempotent To: Victor Nogueira , Cong Wang , netdev@vger.kernel.org Cc: jhs@mojatatu.com, jiri@resnulli.us, alan@wylie.me.uk References: <20250428232955.1740419-1-xiyou.wangcong@gmail.com> <20250428232955.1740419-2-xiyou.wangcong@gmail.com> Content-Language: en-US From: Paolo Abeni In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 4/30/25 5:19 PM, Victor Nogueira wrote: > If that's so, couldn't we instead of doing: > >> @@ -348,7 +348,8 @@ static void htb_add_to_wait_tree(struct htb_sched *q, >> */ >> static inline void htb_next_rb_node(struct rb_node **n) >> { >> - *n = rb_next(*n); >> + if (*n) >> + *n = rb_next(*n); >> } > > do something like: > > @@ -921,7 +921,9 @@ static struct sk_buff *htb_dequeue_tree(struct > htb_sched *q, const int prio, > cl->leaf.deficit[level] -= qdisc_pkt_len(skb); > if (cl->leaf.deficit[level] < 0) { > cl->leaf.deficit[level] += cl->quantum; > - htb_next_rb_node(level ? > &cl->parent->inner.clprio[prio].ptr : > + /* Account for (fq_)codel child deactivating > after dequeue */ > + if (likely(cl->prio_activity)) > + htb_next_rb_node(level ? > &cl->parent->inner.clprio[prio].ptr : > > &q->hlevel[0].hprio[prio].ptr); > } > /* this used to be after charge_class but this constelation > > That way it's clear that the issue is a corner case where the > child qdisc deactivates the parent. Otherwise it seems like > we need to check for (*n) being NULL for every call to > htb_next_rb_node. @Victor, I think that the Cong's suggested patch is simpler to very/tie to code change to the actually addressed issue. I started at your suggest code for a bit, and out of sheer htb ignorance I'm less confident about it fixing the thing. Do you have strong feeling vs Cong's suggested approach? Thanks, Paolo