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
WARNING: multiple messages have this Message-ID (diff)
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 ______________________________________________________ Linux MTD discussion mailing list http://lists.infradead.org/mailman/listinfo/linux-mtd/
next reply other threads:[~2022-05-24 4:49 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-24 4:48 Duoming Zhou [this message] 2022-05-24 4:48 ` [PATCH] mtd: Fix deadlock caused by cancel_work_sync in sm_release Duoming Zhou 2022-06-09 12:42 ` Miquel Raynal 2022-06-09 12:42 ` Miquel Raynal -- strict thread matches above, loose matches on Subject: below -- 2022-05-20 15:04 Duoming Zhou 2022-05-20 15:04 ` Duoming Zhou
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