Messages in this thread Patch in this message | | | From | Duoming Zhou <> | Subject | [PATCH] mtd: Fix deadlock caused by cancel_work_sync in sm_release | Date | Tue, 24 May 2022 12:48:41 +0800 |
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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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