Re: [PATCH V6 07/13] perf: Generic pci uncore device support

From: Peter Zijlstra
Date: Fri Jun 15 2012 - 12:03:00 EST


On Fri, 2012-06-15 at 14:31 +0800, Yan, Zheng wrote:
> @@ -305,6 +310,22 @@ struct intel_uncore_box *uncore_alloc_box(int cpu)
> static struct intel_uncore_box *
> uncore_pmu_to_box(struct intel_uncore_pmu *pmu, int cpu)
> {
> + static struct intel_uncore_box *box;
> +
> + box = *per_cpu_ptr(pmu->box, cpu);
> + if (box)
> + return box;
> +
> + raw_spin_lock(&uncore_box_lock);
> + list_for_each_entry(box, &pmu->box_list, list) {
> + if (box->phys_id == topology_physical_package_id(cpu)) {
> + atomic_inc(&box->refcnt);
> + *per_cpu_ptr(pmu->box, cpu) = box;
> + break;
> + }
> + }
> + raw_spin_unlock(&uncore_box_lock);
> +
> return *per_cpu_ptr(pmu->box, cpu);
> }

So why can't we do that lookup from a hotplug notifier?
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