Messages in this thread |  | | Subject | Re: [Question] null pointer risk of kernel workqueue | | From | tanxiaofei <> | | Date | Mon, 23 Oct 2017 14:23:17 +0800 |
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Hi Bin,
Yes, that's it. thanks.
-- tanxiaofei
On 2017/10/23 9:34, Li Bin wrote: > > > on 2017/10/21 23:35, Tejun Heo wrote: >> On Fri, Oct 20, 2017 at 02:57:18PM +0800, tanxiaofei wrote: >>> Hi Tejun, >>> >>> Any comments about this? >> >> I think you're confused, or at least can't understand what you're >> trying to say. Can you create a rero? >> > > Hi Tejun, > The case is as following: > > worker_thread() > |-spin_lock_irq() > |-process_one_work() > |-worker->current_pwq = pwq > |-spin_unlock_irq() > |-worker->current_func(work) > |-spin_lock_irq() > |-worker->current_pwq = NULL > |-spin_unlock_irq() > //interrupt here > |-irq_handler > |-__queue_work() > //assuming that the wq is draining > |-if (unlikely(wq->flags & __WQ_DRAINING) &&WARN_ON_ONCE(!is_chained_work(wq))) > |-is_chained_work(wq) > |-current_wq_worker() // Here, 'current' is the interrupted worker! > |-current->current_pwq is NULL here! > |-schedule() > > And I think the following patch can solve the bug, right? > > diff --git a/kernel/workqueue_internal.h b/kernel/workqueue_internal.h > index 8635417..650680c 100644 > --- a/kernel/workqueue_internal.h > +++ b/kernel/workqueue_internal.h > @@ -59,7 +59,7 @@ struct worker { > */ > static inline struct worker *current_wq_worker(void) > { > - if (current->flags & PF_WQ_WORKER) > + if (!in_irq() && (current->flags & PF_WQ_WORKER)) > return kthread_data(current); > return NULL; > } > > > Thanks, > Li Bin > >> Thanks. >> > > > . >
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