linux-kernel - [PATCH v5 13/14] dm-raid: fix lockdep waring in "pers->hot_add

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Date: Thu,  1 Feb 2024 17:25:58 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: mpatocka@...hat.com,
	heinzm@...hat.com,
	xni@...hat.com,
	blazej.kucman@...ux.intel.com,
	agk@...hat.com,
	snitzer@...nel.org,
	dm-devel@...ts.linux.dev,
	song@...nel.org,
	yukuai3@...wei.com,
	jbrassow@....redhat.com,
	neilb@...e.de,
	shli@...com,
	akpm@...l.org
Cc: linux-kernel@...r.kernel.org,
	linux-raid@...r.kernel.org,
	yukuai1@...weicloud.com,
	yi.zhang@...wei.com,
	yangerkun@...wei.com
Subject: [PATCH v5 13/14] dm-raid: fix lockdep waring in "pers->hot_add_disk"

From: Yu Kuai <yukuai3@...wei.com>

The lockdep assert is added by commit a448af25becf ("md/raid10: remove
rcu protection to access rdev from conf") in print_conf(). And I didn't
notice that dm-raid is calling "pers->hot_add_disk" without holding
'reconfig_mutex'.

"pers->hot_add_disk" read and write many fields that is protected by
'reconfig_mutex', and raid_resume() already grab the lock in other
contex. Hence fix this problem by protecting "pers->host_add_disk"
with the lock.

Fixes: 9092c02d9435 ("DM RAID: Add ability to restore transiently failed devices on resume")
Fixes: a448af25becf ("md/raid10: remove rcu protection to access rdev from conf")

Signed-off-by: Yu Kuai <yukuai3@...wei.com>
---
 drivers/md/dm-raid.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 16d3348abfed..5f78cc19d6f3 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -4077,7 +4077,9 @@ static void raid_resume(struct dm_target *ti)
 		 * Take this opportunity to check whether any failed
 		 * devices are reachable again.
 		 */
+		mddev_lock_nointr(mddev);
 		attempt_restore_of_faulty_devices(rs);
+		mddev_unlock(mddev);
 	}
 
 	if (test_and_clear_bit(RT_FLAG_RS_SUSPENDED, &rs->runtime_flags)) {
-- 
2.39.2