Messages in this thread | | | Subject | Re: [PATCH v5] arm64: cpuinfo: Expose MIDR_EL1 and REVIDR_EL1 to sysfs | From | Suzuki K Poulose <> | Date | Thu, 16 Jun 2016 17:51:25 +0100 |
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On 16/06/16 17:43, Will Deacon wrote: > 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?
We already check if the CPU is present at runtime before we give out the data.
+#define CPUINFO_ATTR_RO(_name) \ + static ssize_t show_##_name (struct device *dev, \ + struct device_attribute *attr, char *buf) \ + { \ + struct cpuinfo_arm64 *info = &per_cpu(cpu_data, dev->id); \ + if (!cpu_present(dev->id)) \ + return -ENODEV; \ + \
Did you mean to check online/offline ?
Cheers Suzuki
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