From: Duoming Zhou <duoming@zju.edu.cn>
To: linux-mtd@lists.infradead.org
Cc: miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com,
linux-kernel@vger.kernel.org, Duoming Zhou <duoming@zju.edu.cn>
Subject: [PATCH] mtd: Fix deadlock caused by cancel_work_sync in sm_release
Date: Tue, 24 May 2022 12:48:41 +0800 [thread overview]
Message-ID: <20220524044841.10517-1-duoming@zju.edu.cn> (raw)
There is a deadlock between sm_release and sm_cache_flush_work
which is a work item. The cancel_work_sync in sm_release will
not return until sm_cache_flush_work is finished. If we hold
mutex_lock and use cancel_work_sync to wait the work item to
finish, the work item also requires mutex_lock. As a result,
the sm_release will be blocked forever. The race condition is
shown below:
(Thread 1) | (Thread 2)
sm_release |
mutex_lock(&ftl->mutex) | sm_cache_flush_work
| mutex_lock(&ftl->mutex)
cancel_work_sync | ...
This patch moves del_timer_sync and cancel_work_sync out of
mutex_lock in order to mitigate deadlock.
Fixes: 7d17c02a01a1 ("mtd: Add new SmartMedia/xD FTL")
Signed-off-by: Duoming Zhou <duoming@zju.edu.cn>
---
drivers/mtd/sm_ftl.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/mtd/sm_ftl.c b/drivers/mtd/sm_ftl.c
index 0cff2cda1b5..7f955fade83 100644
--- a/drivers/mtd/sm_ftl.c
+++ b/drivers/mtd/sm_ftl.c
@@ -1111,9 +1111,9 @@ static void sm_release(struct mtd_blktrans_dev *dev)
{
struct sm_ftl *ftl = dev->priv;
- mutex_lock(&ftl->mutex);
del_timer_sync(&ftl->timer);
cancel_work_sync(&ftl->flush_work);
+ mutex_lock(&ftl->mutex);
sm_cache_flush(ftl);
mutex_unlock(&ftl->mutex);
}
--
2.17.1
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next reply other threads:[~2022-05-24 4:49 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-24 4:48 Duoming Zhou [this message]
2022-06-09 12:42 ` [PATCH] mtd: Fix deadlock caused by cancel_work_sync in sm_release Miquel Raynal
-- strict thread matches above, loose matches on Subject: below --
2022-05-20 15:04 Duoming Zhou
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