From: Stephen Hemminger <stephen@networkplumber.org>
To: netdev@vger.kernel.org
Cc: Stephen Hemminger <stephen@networkplumber.org>,
Jamal Hadi Salim <jhs@mojatatu.com>,
Jiri Pirko <jiri@resnulli.us>,
"David S. Miller" <davem@davemloft.net>,
Eric Dumazet <edumazet@google.com>,
Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
Simon Horman <horms@kernel.org>,
linux-kernel@vger.kernel.org (open list)
Subject: [PATCH net 2/5] net/sched: netem: fix queue limit check to include reordered packets
Date: Sat, 28 Mar 2026 11:21:46 -0700 [thread overview]
Message-ID: <20260328182336.392817-3-stephen@networkplumber.org> (raw)
In-Reply-To: <20260328182336.392817-1-stephen@networkplumber.org>
The queue limit check in netem_enqueue() uses q->t_len which only
counts packets in the internal tfifo. Packets placed in sch->q by
the reorder path (__qdisc_enqueue_head) are not counted, allowing
the total queue occupancy to exceed sch->limit under reordering.
Include sch->q.qlen in the limit check.
Fixes: 50612537e9ab ("netem: fix classful handling")
Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
---
net/sched/sch_netem.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/sched/sch_netem.c b/net/sched/sch_netem.c
index 2cc3acaa4068..6cc48b698e48 100644
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -523,7 +523,7 @@ static int netem_enqueue(struct sk_buff *skb, struct Qdisc *sch,
1<<get_random_u32_below(8);
}
- if (unlikely(q->t_len >= sch->limit)) {
+ if (unlikely(sch->q.qlen >= sch->limit)) {
/* re-link segs, so that qdisc_drop_all() frees them all */
skb->next = segs;
qdisc_drop_all(skb, sch, to_free);
--
2.53.0
next prev parent reply other threads:[~2026-03-28 18:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-28 18:21 [PATCH net 0/5] net/sched: netem: bug fixes found during AI-assisted review Stephen Hemminger
2026-03-28 18:21 ` [PATCH net 1/5] net/sched: netem: fix probability gaps in 4-state loss model Stephen Hemminger
2026-03-28 18:21 ` Stephen Hemminger [this message]
2026-03-28 18:21 ` [PATCH net 3/5] net/sched: netem: only reseed PRNG when seed is explicitly provided Stephen Hemminger
2026-03-28 18:21 ` [PATCH net 4/5] net/sched: netem: restructure dequeue to avoid re-entrancy with child qdisc Stephen Hemminger
2026-03-28 18:21 ` [PATCH net 5/5] net/sched: netem: null-terminate tfifo linear queue tail Stephen Hemminger
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