Messages in this thread | | | Date | Sat, 6 Jan 2007 20:41:53 +0530 | From | Srivatsa Vaddagiri <> | Subject | Re: [PATCH, RFC] reimplement flush_workqueue() |
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On Fri, Jan 05, 2007 at 03:42:46PM +0300, Oleg Nesterov wrote: > preempt_disable() can't prevent cpu_up, but flush_workqueue() doesn't care > _unless_ cpu_down also happened meantime (and hence a fresh CPU may have > pending work_structs which were moved from a dead CPU).
Yes, that was what I had in mind.
> So you are right, we still need the patch above, but I think we don't have > new problems with preempt_disable().
Right, preempt_disable() hasn't added any new problem. Its just revealing the same problem as earlier, by opening up window for cpu hotplug events to happen in the middle of flush_workqueue().
Ideally I would have liked a lock_cpu_hotplug() equivalent which blocks all cpu hotplug events during the entire flush_workqueue(). In its absence, I guess we just need to deal with all these ugly races ..
In summary, I think we need to go ahead with the preemp_disable() patch in flush_workqueue() from Andrew and the race fix you posted here:
http://lkml.org/lkml/2006/12/30/37
-- Regards, vatsa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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