From mboxrd@z Thu Jan 1 00:00:00 1970 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 6A518EEAA59 for ; Thu, 14 Sep 2023 16:54:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232206AbjINQyw (ORCPT ); Thu, 14 Sep 2023 12:54:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45264 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229705AbjINQyv (ORCPT ); Thu, 14 Sep 2023 12:54:51 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4C3381BCB; Thu, 14 Sep 2023 09:54:47 -0700 (PDT) Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4Rmk1X02Syz6K66F; Fri, 15 Sep 2023 00:54:07 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Thu, 14 Sep 2023 17:54:44 +0100 Date: Thu, 14 Sep 2023 17:54:43 +0100 From: Jonathan Cameron To: James Morse CC: , , , , , , , , , Salil Mehta , Russell King , Jean-Philippe Brucker , , Subject: Re: [RFC PATCH v2 35/35] cpumask: Add enabled cpumask for present CPUs that can be brought online Message-ID: <20230914175443.000038f6@Huawei.com> In-Reply-To: <20230913163823.7880-36-james.morse@arm.com> References: <20230913163823.7880-1-james.morse@arm.com> <20230913163823.7880-36-james.morse@arm.com> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml500005.china.huawei.com (7.191.163.240) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-arch@vger.kernel.org On Wed, 13 Sep 2023 16:38:23 +0000 James Morse wrote: > The 'offline' file in sysfs shows all offline CPUs, including those > that aren't present. User-space is expected to remove not-present CPUs > from this list to learn which CPUs could be brought online. > > CPUs can be present but not-enabled. These CPUs can't be brought online > until the firmware policy changes, which comes with an ACPI notification > that will register the CPUs. > > With only the offline and present files, user-space is unable to > determine which CPUs it can try to bring online. Add a new CPU mask > that shows this based on all the registered CPUs. Bikeshed should be blue. Enabled is a really confusing name for this - to the extent that I'm not sure what it means. Assuming I have the sense right, how about the horrible onlineable or online_capable? > > Signed-off-by: James Morse > --- > drivers/base/cpu.c | 10 ++++++++++ > include/linux/cpumask.h | 25 +++++++++++++++++++++++++ > kernel/cpu.c | 3 +++ > 3 files changed, 38 insertions(+) > > diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c > index c709747c4a18..a19a8be93102 100644 > --- a/drivers/base/cpu.c > +++ b/drivers/base/cpu.c > @@ -95,6 +95,7 @@ void unregister_cpu(struct cpu *cpu) > { > int logical_cpu = cpu->dev.id; > > + set_cpu_enabled(logical_cpu, false); > unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); > > device_unregister(&cpu->dev); > @@ -273,6 +274,13 @@ static ssize_t print_cpus_offline(struct device *dev, > } > static DEVICE_ATTR(offline, 0444, print_cpus_offline, NULL); > > +static ssize_t print_cpus_enabled(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + return sysfs_emit(buf, "%*pbl\n", cpumask_pr_args(cpu_enabled_mask)); > +} > +static DEVICE_ATTR(enabled, 0444, print_cpus_enabled, NULL); > + > static ssize_t print_cpus_isolated(struct device *dev, > struct device_attribute *attr, char *buf) > { > @@ -413,6 +421,7 @@ int register_cpu(struct cpu *cpu, int num) > register_cpu_under_node(num, cpu_to_node(num)); > dev_pm_qos_expose_latency_limit(&cpu->dev, > PM_QOS_RESUME_LATENCY_NO_CONSTRAINT); > + set_cpu_enabled(num, true); > > return 0; > } > @@ -494,6 +503,7 @@ static struct attribute *cpu_root_attrs[] = { > &cpu_attrs[2].attr.attr, > &dev_attr_kernel_max.attr, > &dev_attr_offline.attr, > + &dev_attr_enabled.attr, > &dev_attr_isolated.attr, > #ifdef CONFIG_NO_HZ_FULL > &dev_attr_nohz_full.attr, > diff --git a/include/linux/cpumask.h b/include/linux/cpumask.h > index f10fb87d49db..a29ee03f13ff 100644 > --- a/include/linux/cpumask.h > +++ b/include/linux/cpumask.h > @@ -92,6 +92,7 @@ static inline void set_nr_cpu_ids(unsigned int nr) > * > * cpu_possible_mask- has bit 'cpu' set iff cpu is populatable > * cpu_present_mask - has bit 'cpu' set iff cpu is populated > + * cpu_enabled_mask - has bit 'cpu' set iff cpu can be brought online > * cpu_online_mask - has bit 'cpu' set iff cpu available to scheduler > * cpu_active_mask - has bit 'cpu' set iff cpu available to migration > * > @@ -124,11 +125,13 @@ static inline void set_nr_cpu_ids(unsigned int nr) > > extern struct cpumask __cpu_possible_mask; > extern struct cpumask __cpu_online_mask; > +extern struct cpumask __cpu_enabled_mask; > extern struct cpumask __cpu_present_mask; > extern struct cpumask __cpu_active_mask; > extern struct cpumask __cpu_dying_mask; > #define cpu_possible_mask ((const struct cpumask *)&__cpu_possible_mask) > #define cpu_online_mask ((const struct cpumask *)&__cpu_online_mask) > +#define cpu_enabled_mask ((const struct cpumask *)&__cpu_enabled_mask) > #define cpu_present_mask ((const struct cpumask *)&__cpu_present_mask) > #define cpu_active_mask ((const struct cpumask *)&__cpu_active_mask) > #define cpu_dying_mask ((const struct cpumask *)&__cpu_dying_mask) > @@ -973,6 +976,7 @@ extern const DECLARE_BITMAP(cpu_all_bits, NR_CPUS); > #else > #define for_each_possible_cpu(cpu) for_each_cpu((cpu), cpu_possible_mask) > #define for_each_online_cpu(cpu) for_each_cpu((cpu), cpu_online_mask) > +#define for_each_enabled_cpu(cpu) for_each_cpu((cpu), cpu_enabled_mask) > #define for_each_present_cpu(cpu) for_each_cpu((cpu), cpu_present_mask) > #endif > > @@ -995,6 +999,15 @@ set_cpu_possible(unsigned int cpu, bool possible) > cpumask_clear_cpu(cpu, &__cpu_possible_mask); > } > > +static inline void > +set_cpu_enabled(unsigned int cpu, bool can_be_onlined) > +{ > + if (can_be_onlined) > + cpumask_set_cpu(cpu, &__cpu_enabled_mask); > + else > + cpumask_clear_cpu(cpu, &__cpu_enabled_mask); > +} > + > static inline void > set_cpu_present(unsigned int cpu, bool present) > { > @@ -1074,6 +1087,7 @@ static __always_inline unsigned int num_online_cpus(void) > return raw_atomic_read(&__num_online_cpus); > } > #define num_possible_cpus() cpumask_weight(cpu_possible_mask) > +#define num_enabled_cpus() cpumask_weight(cpu_enabled_mask) > #define num_present_cpus() cpumask_weight(cpu_present_mask) > #define num_active_cpus() cpumask_weight(cpu_active_mask) > > @@ -1082,6 +1096,11 @@ static inline bool cpu_online(unsigned int cpu) > return cpumask_test_cpu(cpu, cpu_online_mask); > } > > +static inline bool cpu_enabled(unsigned int cpu) > +{ > + return cpumask_test_cpu(cpu, cpu_enabled_mask); > +} > + > static inline bool cpu_possible(unsigned int cpu) > { > return cpumask_test_cpu(cpu, cpu_possible_mask); > @@ -1106,6 +1125,7 @@ static inline bool cpu_dying(unsigned int cpu) > > #define num_online_cpus() 1U > #define num_possible_cpus() 1U > +#define num_enabled_cpus() 1U > #define num_present_cpus() 1U > #define num_active_cpus() 1U > > @@ -1119,6 +1139,11 @@ static inline bool cpu_possible(unsigned int cpu) > return cpu == 0; > } > > +static inline bool cpu_enabled(unsigned int cpu) > +{ > + return cpu == 0; > +} > + > static inline bool cpu_present(unsigned int cpu) > { > return cpu == 0; > diff --git a/kernel/cpu.c b/kernel/cpu.c > index 6de7c6bb74ee..2201a6a449b5 100644 > --- a/kernel/cpu.c > +++ b/kernel/cpu.c > @@ -3101,6 +3101,9 @@ EXPORT_SYMBOL(__cpu_possible_mask); > struct cpumask __cpu_online_mask __read_mostly; > EXPORT_SYMBOL(__cpu_online_mask); > > +struct cpumask __cpu_enabled_mask __read_mostly; > +EXPORT_SYMBOL(__cpu_enabled_mask); > + > struct cpumask __cpu_present_mask __read_mostly; > EXPORT_SYMBOL(__cpu_present_mask); >