5.4-stable review patch. If anyone has any objections, please let me know.
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From: Xiang Mei xmei5@asu.edu
[ Upstream commit cf074eca0065bc5142e6004ae236bb35a2687fdf ]
might_sleep could be trigger in the atomic context in qfq_delete_class.
qfq_destroy_class was moved into atomic context locked by sch_tree_lock to avoid a race condition bug on qfq_aggregate. However, might_sleep could be triggered by qfq_destroy_class, which introduced sleeping in atomic context (path: qfq_destroy_class->qdisc_put->__qdisc_destroy->lockdep_unregister_key ->might_sleep).
Considering the race is on the qfq_aggregate objects, keeping qfq_rm_from_agg in the lock but moving the left part out can solve this issue.
Fixes: 5e28d5a3f774 ("net/sched: sch_qfq: Fix race condition on qfq_aggregate") Reported-by: Dan Carpenter dan.carpenter@linaro.org Signed-off-by: Xiang Mei xmei5@asu.edu Link: https://patch.msgid.link/4a04e0cc-a64b-44e7-9213-2880ed641d77@sabinyo.mounta... Reviewed-by: Cong Wang xiyou.wangcong@gmail.com Reviewed-by: Dan Carpenter dan.carpenter@linaro.org Link: https://patch.msgid.link/20250717230128.159766-1-xmei5@asu.edu Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/sched/sch_qfq.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-)
diff --git a/net/sched/sch_qfq.c b/net/sched/sch_qfq.c index 2a4331a084949..be04fcfcc5852 100644 --- a/net/sched/sch_qfq.c +++ b/net/sched/sch_qfq.c @@ -534,9 +534,6 @@ static int qfq_change_class(struct Qdisc *sch, u32 classid, u32 parentid,
static void qfq_destroy_class(struct Qdisc *sch, struct qfq_class *cl) { - struct qfq_sched *q = qdisc_priv(sch); - - qfq_rm_from_agg(q, cl); gen_kill_estimator(&cl->rate_est); qdisc_put(cl->qdisc); kfree(cl); @@ -554,10 +551,11 @@ static int qfq_delete_class(struct Qdisc *sch, unsigned long arg)
qdisc_purge_queue(cl->qdisc); qdisc_class_hash_remove(&q->clhash, &cl->common); - qfq_destroy_class(sch, cl); + qfq_rm_from_agg(q, cl);
sch_tree_unlock(sch);
+ qfq_destroy_class(sch, cl); return 0; }
@@ -1507,6 +1505,7 @@ static void qfq_destroy_qdisc(struct Qdisc *sch) for (i = 0; i < q->clhash.hashsize; i++) { hlist_for_each_entry_safe(cl, next, &q->clhash.hash[i], common.hnode) { + qfq_rm_from_agg(q, cl); qfq_destroy_class(sch, cl); } }