[PATCH net] net/sched: sch_fq_codel: remove data-races from fq_codel_dump_stats()

[PATCH net] net/sched: sch_fq_codel: remove data-races from fq_codel_dump_stats()

[Eric Dumazet]

fq_codel_dump_stats() acquires the qdisc spinlock a bit too late.

Move this acquisition before we fill st.qdisc_stats with live data.

Fixes: edb09eb17ed8 ("net: sched: do not acquire qdisc spinlock in qdisc/class stats dump")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
---
 net/sched/sch_fq_codel.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sched/sch_fq_codel.c b/net/sched/sch_fq_codel.c
index 2a3d758f67ab43d17128442fd8b51c6ba7775d52..0664b2f2d6f28041e5250a44fc92311116ae0cf1 100644
--- a/net/sched/sch_fq_codel.c
+++ b/net/sched/sch_fq_codel.c
@@ -585,6 +585,8 @@ static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 	};
 	struct list_head *pos;
 
+	sch_tree_lock(sch);
+
 	st.qdisc_stats.maxpacket = q->cstats.maxpacket;
 	st.qdisc_stats.drop_overlimit = q->drop_overlimit;
 	st.qdisc_stats.ecn_mark = q->cstats.ecn_mark;
@@ -593,7 +595,6 @@ static int fq_codel_dump_stats(struct Qdisc *sch, struct gnet_dump *d)
 	st.qdisc_stats.memory_usage  = q->memory_usage;
 	st.qdisc_stats.drop_overmemory = q->drop_overmemory;
 
-	sch_tree_lock(sch);
 	list_for_each(pos, &q->new_flows)
 		st.qdisc_stats.new_flows_len++;
 
-- 
2.54.0.rc2.533.g4f5dca5207-goog

Re: [PATCH net] net/sched: sch_fq_codel: remove data-races from fq_codel_dump_stats()

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Tue, 21 Apr 2026 14:25:09 +0000 you wrote:
> fq_codel_dump_stats() acquires the qdisc spinlock a bit too late.
> 
> Move this acquisition before we fill st.qdisc_stats with live data.
> 
> Fixes: edb09eb17ed8 ("net: sched: do not acquire qdisc spinlock in qdisc/class stats dump")
> Signed-off-by: Eric Dumazet <edumazet@google.com>
> Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
> 
> [...]

Here is the summary with links:
  - [net] net/sched: sch_fq_codel: remove data-races from fq_codel_dump_stats()
    https://git.kernel.org/netdev/net/c/bbfaa73ea687

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html