Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758633AbaGYBIs (ORCPT ); Thu, 24 Jul 2014 21:08:48 -0400 Received: from smtp.codeaurora.org ([198.145.11.231]:34436 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752054AbaGYBHo (ORCPT ); Thu, 24 Jul 2014 21:07:44 -0400 From: Saravana Kannan To: "Rafael J . Wysocki" , Viresh Kumar , Todd Poynor , "Srivatsa S . Bhat" Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, "Saravana Kannan" , Stephen Boyd Subject: [PATCH v4 3/5] cpufreq: Don't destroy/realloc policy/sysfs on hotplug/suspend Date: Thu, 24 Jul 2014 18:07:26 -0700 Message-Id: <1406250448-470-4-git-send-email-skannan@codeaurora.org> X-Mailer: git-send-email 1.8.2.1 In-Reply-To: <1406250448-470-1-git-send-email-skannan@codeaurora.org> References: <1406250448-470-1-git-send-email-skannan@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch simplifies a lot of the hotplug/suspend code by not adding/removing/moving the policy/sysfs/kobj during hotplug and just leaves the cpufreq directory and policy in place irrespective of whether the CPUs are ONLINE/OFFLINE. Leaving the policy, sysfs and kobject in place also brings these additional benefits: * Faster suspend/resume * Faster hotplug * Sysfs file permissions maintained across hotplug * Policy settings and governor tunables maintained across hotplug * Cpufreq stats would be maintained across hotplug for all CPUs and can be queried even after CPU goes OFFLINE Signed-off-by: Saravana Kannan --- drivers/cpufreq/cpufreq.c | 83 ++++++++++++++++------------------------------- 1 file changed, 28 insertions(+), 55 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index af4f291..d9fc6e5 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -865,7 +865,7 @@ static int cpufreq_add_dev_symlink(struct cpufreq_policy *policy) unsigned int j; int ret = 0; - for_each_cpu(j, policy->cpus) { + for_each_cpu(j, policy->related_cpus) { struct device *cpu_dev; if (j == policy->kobj_cpu) @@ -968,7 +968,7 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, int ret = 0; unsigned long flags; - if (has_target()) { + if (cpumask_weight(policy->cpus) && has_target()) { ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP); if (ret) { pr_err("%s: Failed to stop governor\n", __func__); @@ -997,7 +997,7 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, } } - return sysfs_create_link(&dev->kobj, &policy->kobj, "cpufreq"); + return 0; } #endif @@ -1100,9 +1100,6 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) struct cpufreq_policy *policy; unsigned long flags; bool recover_policy = cpufreq_suspended; -#ifdef CONFIG_HOTPLUG_CPU - struct cpufreq_policy *tpolicy; -#endif if (cpu_is_offline(cpu)) return 0; @@ -1113,28 +1110,22 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) /* check whether a different CPU already registered this * CPU because it is in the same boat. */ policy = cpufreq_cpu_get(cpu); - if (unlikely(policy)) { + if (policy) { + if (!cpumask_test_cpu(cpu, policy->cpus)) + ret = cpufreq_add_policy_cpu(policy, cpu, dev); + else + ret = 0; cpufreq_cpu_put(policy); - return 0; + return ret; } #endif if (!down_read_trylock(&cpufreq_rwsem)) return 0; -#ifdef CONFIG_HOTPLUG_CPU - /* Check if this cpu was hot-unplugged earlier and has siblings */ - read_lock_irqsave(&cpufreq_driver_lock, flags); - list_for_each_entry(tpolicy, &cpufreq_policy_list, policy_list) { - if (cpumask_test_cpu(cpu, tpolicy->related_cpus)) { - read_unlock_irqrestore(&cpufreq_driver_lock, flags); - ret = cpufreq_add_policy_cpu(tpolicy, cpu, dev); - up_read(&cpufreq_rwsem); - return ret; - } - } - read_unlock_irqrestore(&cpufreq_driver_lock, flags); -#endif + /* If we get this far, this is the first time we are adding the + * policy */ + recover_policy = false; /* * Restore the saved policy when doing light-weight init and fall back @@ -1189,7 +1180,7 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) down_write(&policy->rwsem); write_lock_irqsave(&cpufreq_driver_lock, flags); - for_each_cpu(j, policy->cpus) + for_each_cpu(j, policy->related_cpus) per_cpu(cpufreq_cpu_data, j) = policy; write_unlock_irqrestore(&cpufreq_driver_lock, flags); @@ -1274,7 +1265,7 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) err_out_unregister: err_get_freq: write_lock_irqsave(&cpufreq_driver_lock, flags); - for_each_cpu(j, policy->cpus) + for_each_cpu(j, policy->related_cpus) per_cpu(cpufreq_cpu_data, j) = NULL; write_unlock_irqrestore(&cpufreq_driver_lock, flags); @@ -1340,21 +1331,15 @@ static int __cpufreq_remove_dev_prepare(struct device *dev, struct subsys_interface *sif) { unsigned int cpu = dev->id, cpus; - int new_cpu, ret; + int new_cpu, ret = 0; unsigned long flags; struct cpufreq_policy *policy; pr_debug("%s: unregistering CPU %u\n", __func__, cpu); - write_lock_irqsave(&cpufreq_driver_lock, flags); - + read_lock_irqsave(&cpufreq_driver_lock, flags); policy = per_cpu(cpufreq_cpu_data, cpu); - - /* Save the policy somewhere when doing a light-weight tear-down */ - if (cpufreq_suspended) - per_cpu(cpufreq_cpu_data_fallback, cpu) = policy; - - write_unlock_irqrestore(&cpufreq_driver_lock, flags); + read_unlock_irqrestore(&cpufreq_driver_lock, flags); if (!policy) { pr_debug("%s: No cpu_data found\n", __func__); @@ -1369,24 +1354,15 @@ static int __cpufreq_remove_dev_prepare(struct device *dev, } } - if (!cpufreq_driver->setpolicy) - strncpy(per_cpu(cpufreq_cpu_governor, cpu), - policy->governor->name, CPUFREQ_NAME_LEN); - down_read(&policy->rwsem); cpus = cpumask_weight(policy->cpus); up_read(&policy->rwsem); - if (cpu != policy->cpu) { - sysfs_remove_link(&dev->kobj, "cpufreq"); - } else if (cpus > 1) { - new_cpu = cpufreq_nominate_new_policy_cpu(policy, cpu); - if (new_cpu >= 0) { - update_policy_cpu(policy, new_cpu); - - if (!cpufreq_suspended) - pr_debug("%s: policy Kobject moved to cpu: %d from: %d\n", - __func__, new_cpu, cpu); + if (cpus > 1) { + if (cpu == policy->cpu) { + new_cpu = cpumask_any_but(policy->cpus, cpu); + if (new_cpu >= 0) + update_policy_cpu(policy, new_cpu); } } else if (cpufreq_driver->stop_cpu && cpufreq_driver->setpolicy) { cpufreq_driver->stop_cpu(policy); @@ -1431,6 +1407,9 @@ static int __cpufreq_remove_dev_finish(struct device *dev, cpus = cpumask_weight(policy->cpus); up_read(&policy->rwsem); + if (cpu != policy->kobj_cpu) + sysfs_remove_link(&dev->kobj, "cpufreq"); + /* If cpu is last user of policy, free policy */ if (cpus == 0) { if (has_target()) { @@ -1475,12 +1454,10 @@ static int __cpufreq_remove_dev_finish(struct device *dev, static int cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif) { unsigned int cpu = dev->id; - int ret; - - if (cpu_is_offline(cpu)) - return 0; + int ret = 0; - ret = __cpufreq_remove_dev_prepare(dev, sif); + if (cpu_online(cpu)) + ret = __cpufreq_remove_dev_prepare(dev, sif); if (!ret) ret = __cpufreq_remove_dev_finish(dev, sif); @@ -2307,10 +2284,6 @@ static int cpufreq_cpu_callback(struct notifier_block *nfb, __cpufreq_remove_dev_prepare(dev, NULL); break; - case CPU_POST_DEAD: - __cpufreq_remove_dev_finish(dev, NULL); - break; - case CPU_DOWN_FAILED: __cpufreq_add_dev(dev, NULL); break; 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