Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     David Sloan <david.sloan@eideticom.com>,
        Logan Gunthorpe <logang@deltatee.com>,
        Song Liu <song@kernel.org>, Sasha Levin <sashal@kernel.org>,
        linux-raid@vger.kernel.org
Subject: [PATCH AUTOSEL 5.19 26/33] md: Flush workqueue md_rdev_misc_wq in md_alloc()
Date:   Tue, 30 Aug 2022 13:18:17 -0400
Message-Id: <20220830171825.580603-26-sashal@kernel.org>
In-Reply-To: <20220830171825.580603-1-sashal@kernel.org>
References: <20220830171825.580603-1-sashal@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: David Sloan <david.sloan@eideticom.com>

[ Upstream commit 5e8daf906f890560df430d30617c692a794acb73 ]

A race condition still exists when removing and re-creating md devices
in test cases. However, it is only seen on some setups.

The race condition was tracked down to a reference still being held
to the kobject by the rdev in the md_rdev_misc_wq which will be released
in rdev_delayed_delete().

md_alloc() waits for previous deletions by waiting on the md_misc_wq,
but the md_rdev_misc_wq may still be holding a reference to a recently
removed device.

To fix this, also flush the md_rdev_misc_wq in md_alloc().

Signed-off-by: David Sloan <david.sloan@eideticom.com>
[logang@deltatee.com: rewrote commit message]
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/md.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 522b3d6b8c46b..3f31db141b2f2 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -5647,6 +5647,7 @@ static int md_alloc(dev_t dev, char *name)
 	 * removed (mddev_delayed_delete).
 	 */
 	flush_workqueue(md_misc_wq);
+	flush_workqueue(md_rdev_misc_wq);
 
 	mutex_lock(&disks_mutex);
 	mddev = mddev_alloc(dev);
-- 
2.35.1