[dm-devel] corruption causing crash in __queue_work
Tejun Heo
tj at kernel.org
Thu Dec 17 15:50:32 UTC 2015
Hello, Nikolay.
On Thu, Dec 17, 2015 at 05:43:12PM +0200, Nikolay Borisov wrote:
> Right, but my initial understanding was that when canceling the delayed
> work and then issuing flush_workqueue would act the same way as if
> cancel_delayed_work_sync is called wrt to this particular delayed item, no?
Not necessarily. cancel_delayed_work() cancels whatever is currently
pending. flush_workqueue() flushes whatever is pending and in flight
at the time of invocation. Imagine the following scenario.
1. Work item is running but hasn't requeued itself yet.
2. cancel_delayed_work_sync() doesn't do anything as it's not pending.
3. flush_workqueue() starts and waits for the running instance.
4. The running instance requeues itself but this isn't included in the
scope of the above flush_workqueue().
5. flush_workqueue() returns when the work item is finished (but it's
still queued).
Thanks.
--
tejun
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