This is a note to let you know that I've just added the patch titled
net: sched: tbf: don't call qdisc_put() while holding tree lock
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-sched-tbf-don-t-call-qdisc_put-while-holding-tre.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit bea2b223dc1190c0737f1b51ef5292ae0860048d
Author: Zhengchao Shao <shaozhengchao@xxxxxxxxxx>
Date: Fri Aug 26 09:39:30 2022 +0800
net: sched: tbf: don't call qdisc_put() while holding tree lock
[ Upstream commit b05972f01e7d30419987a1f221b5593668fd6448 ]
The issue is the same to commit c2999f7fb05b ("net: sched: multiq: don't
call qdisc_put() while holding tree lock"). Qdiscs call qdisc_put() while
holding sch tree spinlock, which results sleeping-while-atomic BUG.
Fixes: c266f64dbfa2 ("net: sched: protect block state with mutex")
Signed-off-by: Zhengchao Shao <shaozhengchao@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20220826013930.340121-1-shaozhengchao@xxxxxxxxxx
Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 5f72f3f916a5a..a7f60bb2dd513 100644
--- a/net/sched/sch_tbf.c
+++ b/net/sched/sch_tbf.c
@@ -297,6 +297,7 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt,
struct nlattr *tb[TCA_TBF_MAX + 1];
struct tc_tbf_qopt *qopt;
struct Qdisc *child = NULL;
+ struct Qdisc *old = NULL;
struct psched_ratecfg rate;
struct psched_ratecfg peak;
u64 max_size;
@@ -388,7 +389,7 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt,
sch_tree_lock(sch);
if (child) {
qdisc_tree_flush_backlog(q->qdisc);
- qdisc_put(q->qdisc);
+ old = q->qdisc;
q->qdisc = child;
}
q->limit = qopt->limit;
@@ -408,6 +409,7 @@ static int tbf_change(struct Qdisc *sch, struct nlattr *opt,
memcpy(&q->peak, &peak, sizeof(struct psched_ratecfg));
sch_tree_unlock(sch);
+ qdisc_put(old);
err = 0;
done:
return err;
