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@huawei.com>
Link: https://lore.kernel.org/r/20220826013930.340121-1-shaozhengchao@huawei.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/sched/sch_tbf.c b/net/sched/sch_tbf.c
index 5f72f3f916a5a6c030eccc67332d6c86795dca4b..a7f60bb2dd513860abf7257d02255e48c5f5ecb4 100644 (file)
--- 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;