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SubjectRe: [PATCH v5] arm64: cpuinfo: Expose MIDR_EL1 and REVIDR_EL1 to sysfs
On Thu, Jun 16, 2016 at 02:28:50PM +0100, Suzuki K Poulose wrote:
> +static int __init cpuinfo_regs_init(void)
> +{
> + int cpu, finalcpu, ret;
> + struct device *dev;
> +
> + cpu_hotplug_disable();
> +
> + for_each_present_cpu(cpu) {
> + dev = get_cpu_device(cpu);
> +
> + if (!dev) {
> + ret = -ENODEV;
> + break;
> + }
> +
> + ret = sysfs_create_group(&dev->kobj, &cpuregs_attr_group);
> + if (ret)
> + break;
> + }
> +
> + if (!ret)
> + goto out;
> + /*
> + * We were unable to put down sysfs groups for all the CPUs, revert
> + * all the groups we have placed down s.t. none are visible.
> + * Otherwise we could give a misleading picture of what's present.
> + */
> + finalcpu = cpu;
> + for_each_present_cpu(cpu) {
> + if (cpu == finalcpu)
> + break;
> + dev = get_cpu_device(cpu);
> + if (dev)
> + sysfs_remove_group(&dev->kobj, &cpuregs_attr_group);
> + }
> +
> +out:
> + cpu_hotplug_enable();
> + return ret;
> +}
> +
> +device_initcall(cpuinfo_regs_init);

Given that you're built the sysfs entries out of the present mask, don't
you need a hotplug notifier to keep things up to date?

Will

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