[PATCH AUTOSEL 5.10 07/10] net: sched: fix ordering of qlen adjustment

Sasha Levin
2024-12-11T18:54:34Z

From: Lion Ackermann <nnamrec@gmail.com>

[ Upstream commit 5eb7de8cd58e73851cd37ff8d0666517d9926948 ]

Changes to sch->q.qlen around qdisc_tree_reduce_backlog() need to happen
_before_ a call to said function because otherwise it may fail to notify
parent qdiscs when the child is about to become empty.

Signed-off-by: Lion Ackermann <nnamrec@gmail.com>
Acked-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sched/sch_cake.c | 2 +-
net/sched/sch_choke.c | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/sched/sch_cake.c b/net/sched/sch_cake.c
index 4ddb43a6644ab..8d9c0b98a747b 100644
--- a/net/sched/sch_cake.c
+++ b/net/sched/sch_cake.c
@@ -1541,7 +1541,6 @@ static unsigned int cake_drop(struct Qdisc *sch, struct sk_buff **to_free)
b->backlogs[idx] -= len;
b->tin_backlog -= len;
sch->qstats.backlog -= len;
- qdisc_tree_reduce_backlog(sch, 1, len);

flow->dropped++;
b->tin_dropped++;
@@ -1552,6 +1551,7 @@ static unsigned int cake_drop(struct Qdisc *sch, struct sk_buff **to_free)

__qdisc_drop(skb, to_free);
sch->q.qlen--;
+ qdisc_tree_reduce_backlog(sch, 1, len);

cake_heapify(q, 0);

diff --git a/net/sched/sch_choke.c b/net/sched/sch_choke.c
index 25d2daaa81227..f3805bee995bb 100644
--- a/net/sched/sch_choke.c
+++ b/net/sched/sch_choke.c
@@ -124,10 +124,10 @@ static void choke_drop_by_idx(struct Qdisc *sch, unsigned int idx,
if (idx == q->tail)
choke_zap_tail_holes(q);

+ --sch->q.qlen;
qdisc_qstats_backlog_dec(sch, skb);
qdisc_tree_reduce_backlog(sch, 1, qdisc_pkt_len(skb));
qdisc_drop(skb, sch, to_free);
- --sch->q.qlen;
}

struct choke_skb_cb {
--
2.43.0