Messages in this thread |  | | | Date | Fri, 6 Feb 2009 17:46:49 +0100 | | From | Oleg Nesterov <> | | Subject | Re: [PATCH 2/3] workqueue: not allow recursion run_workqueue |
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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.
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