linux-kernel - [PATCH net] net: sched: fix lockdep_set

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Message-ID: <1627988301-55801-1-git-send-email-linyunsheng@huawei.com>
Date:   Tue, 3 Aug 2021 18:58:21 +0800
From:   Yunsheng Lin <linyunsheng@...wei.com>
To:     <davem@...emloft.net>, <kuba@...nel.org>
CC:     <jhs@...atatu.com>, <xiyou.wangcong@...il.com>, <jiri@...nulli.us>,
        <pabeni@...hat.com>, <ap420073@...il.com>,
        <netdev@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linuxarm@...neuler.org>
Subject: [PATCH net] net: sched: fix lockdep_set_class() typo error for sch->seqlock

According to comment in qdisc_alloc(), sch->seqlock's lockdep
class key should be set to qdisc_tx_busylock, due to possible
type error, sch->busylock's lockdep class key is set to
qdisc_tx_busylock, which is duplicated because sch->busylock's
lockdep class key is already set in qdisc_alloc().

So fix it by replacing sch->busylock with sch->seqlock.

Fixes: 96009c7d500e ("sched: replace __QDISC_STATE_RUNNING bit with a spin lock")
Signed-off-by: Yunsheng Lin <linyunsheng@...wei.com>
---
commit ab92d68fc22f ("net: core: add generic lockdep keys")
seems to fix the above error without mentioning that, and then
it is reverted by commit 1a33e10e4a95 ("net: partially revert
dynamic lockdep key changes"), but the blamed commit still be
96009c7d500e ("sched: replace __QDISC_STATE_RUNNING bit with
a spin lock").
---
 net/sched/sch_generic.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index d9ac60f..a8dd06c 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -913,7 +913,7 @@ struct Qdisc *qdisc_alloc(struct netdev_queue *dev_queue,
 
 	/* seqlock has the same scope of busylock, for NOLOCK qdisc */
 	spin_lock_init(&sch->seqlock);
-	lockdep_set_class(&sch->busylock,
+	lockdep_set_class(&sch->seqlock,
 			  dev->qdisc_tx_busylock ?: &qdisc_tx_busylock);
 
 	seqcount_init(&sch->running);
-- 
2.7.4