linux-kernel - [PATCH] [v2] dm raid: fix mddev unlocking in raid

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Date:   Mon,  6 Sep 2021 12:16:16 +0800
From:   Dinghao Liu <dinghao.liu@....edu.cn>
To:     dinghao.liu@....edu.cn, kjlu@....edu
Cc:     Heinz Mauelshagen <heinzm@...hat.com>,
        Alasdair Kergon <agk@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>, dm-devel@...hat.com,
        linux-kernel@...r.kernel.org
Subject: [PATCH] [v2] dm raid: fix mddev unlocking in raid_ctr() error paths

mddev_unlock() is called on all paths after we call mddev_lock_nointr(),
except for three error handling paths, which may cause a deadlock.

Fixes: 9dbd1aa3a81c ("dm raid: add reshaping support to the target")
Signed-off-by: Dinghao Liu <dinghao.liu@....edu.cn>
Signed-off-by: Heinz Mauelshagen <heinzm@...hat.com>
---

Changelog:

v2: - Simplify the error handling paths.
---
 drivers/md/dm-raid.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index d9ef52159a22..741bab00e922 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -3249,14 +3249,12 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	rs->md.in_sync = 0; /* Assume already marked dirty */
 	if (r) {
 		ti->error = "Failed to run raid array";
-		mddev_unlock(&rs->md);
-		goto bad;
+		goto bad_unlock;
 	}
 
 	r = md_start(&rs->md);
 	if (r) {
 		ti->error = "Failed to start raid array";
-		mddev_unlock(&rs->md);
 		goto bad_md_start;
 	}
 
@@ -3265,7 +3263,6 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 		r = r5c_journal_mode_set(&rs->md, rs->journal_dev.mode);
 		if (r) {
 			ti->error = "Failed to set raid4/5/6 journal mode";
-			mddev_unlock(&rs->md);
 			goto bad_journal_mode_set;
 		}
 	}
@@ -3304,10 +3301,12 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
 	mddev_unlock(&rs->md);
 	return 0;
 
+bad_unlock:
 bad_md_start:
 bad_journal_mode_set:
 bad_stripe_cache:
 bad_check_reshape:
+	mddev_unlock(&rs->md);
 	md_stop(&rs->md);
 bad:
 	raid_set_free(rs);
-- 
2.17.1