From mboxrd@z Thu Jan 1 00:00:00 1970 From: Suzuki.Poulose@arm.com (Suzuki K Poulose) Date: Thu, 16 Jun 2016 17:51:25 +0100 Subject: [PATCH v5] arm64: cpuinfo: Expose MIDR_EL1 and REVIDR_EL1 to sysfs In-Reply-To: <20160616164311.GH5827@arm.com> References: <1466083730-11786-1-git-send-email-suzuki.poulose@arm.com> <20160616164311.GH5827@arm.com> Message-ID: <5762D90D.8090303@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org 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 From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753893AbcFPQvn (ORCPT ); Thu, 16 Jun 2016 12:51:43 -0400 Received: from foss.arm.com ([217.140.101.70]:45186 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754219AbcFPQv2 (ORCPT ); Thu, 16 Jun 2016 12:51:28 -0400 Subject: Re: [PATCH v5] arm64: cpuinfo: Expose MIDR_EL1 and REVIDR_EL1 to sysfs To: Will Deacon References: <1466083730-11786-1-git-send-email-suzuki.poulose@arm.com> <20160616164311.GH5827@arm.com> Cc: catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, steve.capper@linaro.org, linux@arm.linux.org.uk, Mark Rutland From: Suzuki K Poulose Message-ID: <5762D90D.8090303@arm.com> Date: Thu, 16 Jun 2016 17:51:25 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.8.0 MIME-Version: 1.0 In-Reply-To: <20160616164311.GH5827@arm.com> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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