From patchwork Wed Sep 13 16:37:59 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: James Morse X-Patchwork-Id: 722150 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A2E57EE01E1 for ; Wed, 13 Sep 2023 16:39:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230504AbjIMQj5 (ORCPT ); Wed, 13 Sep 2023 12:39:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58350 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230387AbjIMQji (ORCPT ); Wed, 13 Sep 2023 12:39:38 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 7B8E71FE5; Wed, 13 Sep 2023 09:39:15 -0700 (PDT) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 3C192C15; Wed, 13 Sep 2023 09:39:52 -0700 (PDT) Received: from merodach.members.linode.com (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 416BC3F5A1; Wed, 13 Sep 2023 09:39:13 -0700 (PDT) From: James Morse To: linux-pm@vger.kernel.org, loongarch@lists.linux.dev, linux-acpi@vger.kernel.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org, kvmarm@lists.linux.dev Cc: x86@kernel.org, Salil Mehta , Russell King , Jean-Philippe Brucker , jianyong.wu@arm.com, justin.he@arm.com Subject: [RFC PATCH v2 11/35] arch_topology: Make register_cpu_capacity_sysctl() tolerant to late CPUs Date: Wed, 13 Sep 2023 16:37:59 +0000 Message-Id: <20230913163823.7880-12-james.morse@arm.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20230913163823.7880-1-james.morse@arm.com> References: <20230913163823.7880-1-james.morse@arm.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org register_cpu_capacity_sysctl() adds a property to sysfs that describes the CPUs capacity. This is done from a subsys_initcall() that assumes all possible CPUs are registered. With CPU hotplug, possible CPUs aren't registered until they become present, (or for arm64 enabled). This leads to messages during boot: | register_cpu_capacity_sysctl: too early to get CPU1 device! and once these CPUs are added to the system, the file is missing. Move this to a cpuhp callback, so that the file is created once CPUs are brought online. This covers CPUs that are added late by mechanisms like hotplug. One observable difference is the file is now missing for offline CPUs. Signed-off-by: James Morse --- If the offline CPUs thing is a problem for the tools that consume this value, we'd need to move cpu_capacity to be part of cpu.c's common_cpu_attr_groups. --- drivers/base/arch_topology.c | 38 ++++++++++++++++++++++++------------ 1 file changed, 26 insertions(+), 12 deletions(-) diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c index b741b5ba82bd..9ccb7daee78e 100644 --- a/drivers/base/arch_topology.c +++ b/drivers/base/arch_topology.c @@ -220,20 +220,34 @@ static DECLARE_WORK(update_topology_flags_work, update_topology_flags_workfn); static DEVICE_ATTR_RO(cpu_capacity); +static int cpu_capacity_sysctl_add(unsigned int cpu) +{ + struct device *cpu_dev = get_cpu_device(cpu); + + if (!cpu_dev) + return -ENOENT; + + device_create_file(cpu_dev, &dev_attr_cpu_capacity); + + return 0; +} + +static int cpu_capacity_sysctl_remove(unsigned int cpu) +{ + struct device *cpu_dev = get_cpu_device(cpu); + + if (!cpu_dev) + return -ENOENT; + + device_remove_file(cpu_dev, &dev_attr_cpu_capacity); + + return 0; +} + static int register_cpu_capacity_sysctl(void) { - int i; - struct device *cpu; - - for_each_possible_cpu(i) { - cpu = get_cpu_device(i); - if (!cpu) { - pr_err("%s: too early to get CPU%d device!\n", - __func__, i); - continue; - } - device_create_file(cpu, &dev_attr_cpu_capacity); - } + cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "topology/cpu-capacity", + cpu_capacity_sysctl_add, cpu_capacity_sysctl_remove); return 0; }