Messages in this thread | | | Date | Mon, 09 Feb 2009 15:20:43 +0800 | From | Lai Jiangshan <> | Subject | Re: [PATCH 2/3] workqueue: not allow recursion run_workqueue |
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Oleg Nesterov wrote: > On 02/06, Lai Jiangshan wrote: >> Oleg Nesterov wrote: >>> On 02/05, Lai Jiangshan wrote: >>>> DEADLOCK EXAMPLE for explain my above option: >>>> >>>> (work_func0() and work_func1() are work callback, and they >>>> calls flush_workqueue()) >>>> >>>> CPU#0 CPU#1 >>>> run_workqueue() run_workqueue() >>>> work_func0() work_func1() >>>> flush_workqueue() flush_workqueue() >>>> flush_cpu_workqueue(0) . >>>> flush_cpu_workqueue(cpu#1) flush_cpu_workqueue(cpu#0) >>>> waiting work_func1() in cpu#1 waiting work_func0 in cpu#0 >>>> >>>> DEADLOCK! >>> I am not sure. Note that when work_func0() calls run_workqueue(), >>> it will clear cwq->current_work, so another flush_ on CPU#1 will >>> not wait for work_func0, no? >> cwq->current_work is changed only when >> !list_empty(&cwq->worklist) >> in run_workqueue(). >> >> so cwq->current_work may not be changed. > > Ah, indeed. > > Thanks for correcting me! > > Oleg. > > > >
Thanks,
Could you Ack these patches?
Lai.
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