From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756262Ab3BDWqC (ORCPT ); Mon, 4 Feb 2013 17:46:02 -0500 Received: from relay1.sgi.com ([192.48.179.29]:58195 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755938Ab3BDWp6 (ORCPT ); Mon, 4 Feb 2013 17:45:58 -0500 From: Nathan Zimmer To: rjw@sisk.pl Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, cpufreq@vger.kernel.org, Nathan Zimmer Subject: [PATCH 1/2] cpufreq: Convert the cpufreq_driver_lock to a rwlock Date: Mon, 4 Feb 2013 16:45:12 -0600 Message-Id: <1360017913-25667-2-git-send-email-nzimmer@sgi.com> X-Mailer: git-send-email 1.8.0.1 In-Reply-To: <1360017913-25667-1-git-send-email-nzimmer@sgi.com> References: <1360017913-25667-1-git-send-email-nzimmer@sgi.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This completely eliminates the contention I am seeing in __cpufreq_cpu_get. It also nicely stages the lock to be replaced by the rcu. CC: "Rafael J. Wysocki" Signed-off-by: Nathan Zimmer --- drivers/cpufreq/cpufreq.c | 44 ++++++++++++++++++++++---------------------- 1 file changed, 22 insertions(+), 22 deletions(-) diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c index 1f93dbd..13a83a2 100644 --- a/drivers/cpufreq/cpufreq.c +++ b/drivers/cpufreq/cpufreq.c @@ -45,7 +45,7 @@ static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data); /* This one keeps track of the previously set governor of a removed CPU */ static DEFINE_PER_CPU(char[CPUFREQ_NAME_LEN], cpufreq_cpu_governor); #endif -static DEFINE_SPINLOCK(cpufreq_driver_lock); +static DEFINE_RWLOCK(cpufreq_driver_lock); /* * cpu_policy_rwsem is a per CPU reader-writer semaphore designed to cure @@ -149,7 +149,7 @@ static struct cpufreq_policy *__cpufreq_cpu_get(unsigned int cpu, bool sysfs) goto err_out; /* get the cpufreq driver */ - spin_lock_irqsave(&cpufreq_driver_lock, flags); + read_lock_irqsave(&cpufreq_driver_lock, flags); if (!cpufreq_driver) goto err_out_unlock; @@ -167,13 +167,13 @@ static struct cpufreq_policy *__cpufreq_cpu_get(unsigned int cpu, bool sysfs) if (!sysfs && !kobject_get(&data->kobj)) goto err_out_put_module; - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + read_unlock_irqrestore(&cpufreq_driver_lock, flags); return data; err_out_put_module: module_put(cpufreq_driver->owner); err_out_unlock: - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + read_unlock_irqrestore(&cpufreq_driver_lock, flags); err_out: return NULL; } @@ -751,10 +751,10 @@ static int cpufreq_add_dev_policy(unsigned int cpu, return -EBUSY; } - spin_lock_irqsave(&cpufreq_driver_lock, flags); + write_lock_irqsave(&cpufreq_driver_lock, flags); cpumask_copy(managed_policy->cpus, policy->cpus); per_cpu(cpufreq_cpu_data, cpu) = managed_policy; - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + write_unlock_irqrestore(&cpufreq_driver_lock, flags); pr_debug("CPU already managed, adding link\n"); ret = sysfs_create_link(&dev->kobj, @@ -850,14 +850,14 @@ static int cpufreq_add_dev_interface(unsigned int cpu, goto err_out_kobj_put; } - spin_lock_irqsave(&cpufreq_driver_lock, flags); + write_lock_irqsave(&cpufreq_driver_lock, flags); for_each_cpu(j, policy->cpus) { if (!cpu_online(j)) continue; per_cpu(cpufreq_cpu_data, j) = policy; per_cpu(cpufreq_policy_cpu, j) = policy->cpu; } - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + write_unlock_irqrestore(&cpufreq_driver_lock, flags); ret = cpufreq_add_dev_symlink(cpu, policy); if (ret) @@ -999,10 +999,10 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif) err_out_unregister: - spin_lock_irqsave(&cpufreq_driver_lock, flags); + write_lock_irqsave(&cpufreq_driver_lock, flags); for_each_cpu(j, policy->cpus) per_cpu(cpufreq_cpu_data, j) = NULL; - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + write_unlock_irqrestore(&cpufreq_driver_lock, flags); kobject_put(&policy->kobj); wait_for_completion(&policy->kobj_unregister); @@ -1042,11 +1042,11 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif pr_debug("unregistering CPU %u\n", cpu); - spin_lock_irqsave(&cpufreq_driver_lock, flags); + write_lock_irqsave(&cpufreq_driver_lock, flags); data = per_cpu(cpufreq_cpu_data, cpu); if (!data) { - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + write_unlock_irqrestore(&cpufreq_driver_lock, flags); unlock_policy_rwsem_write(cpu); return -EINVAL; } @@ -1060,7 +1060,7 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif if (unlikely(cpu != data->cpu)) { pr_debug("removing link\n"); cpumask_clear_cpu(cpu, data->cpus); - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + write_unlock_irqrestore(&cpufreq_driver_lock, flags); kobj = &dev->kobj; cpufreq_cpu_put(data); unlock_policy_rwsem_write(cpu); @@ -1089,7 +1089,7 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif } } - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + write_unlock_irqrestore(&cpufreq_driver_lock, flags); if (unlikely(cpumask_weight(data->cpus) > 1)) { for_each_cpu(j, data->cpus) { @@ -1109,7 +1109,7 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif } } #else - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + write_unlock_irqrestore(&cpufreq_driver_lock, flags); #endif if (cpufreq_driver->target) @@ -1878,13 +1878,13 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) if (driver_data->setpolicy) driver_data->flags |= CPUFREQ_CONST_LOOPS; - spin_lock_irqsave(&cpufreq_driver_lock, flags); + write_lock_irqsave(&cpufreq_driver_lock, flags); if (cpufreq_driver) { - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + write_unlock_irqrestore(&cpufreq_driver_lock, flags); return -EBUSY; } cpufreq_driver = driver_data; - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + write_unlock_irqrestore(&cpufreq_driver_lock, flags); ret = subsys_interface_register(&cpufreq_interface); if (ret) @@ -1916,9 +1916,9 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data) err_if_unreg: subsys_interface_unregister(&cpufreq_interface); err_null_driver: - spin_lock_irqsave(&cpufreq_driver_lock, flags); + write_lock_irqsave(&cpufreq_driver_lock, flags); cpufreq_driver = NULL; - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + write_unlock_irqrestore(&cpufreq_driver_lock, flags); return ret; } EXPORT_SYMBOL_GPL(cpufreq_register_driver); @@ -1944,9 +1944,9 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver) subsys_interface_unregister(&cpufreq_interface); unregister_hotcpu_notifier(&cpufreq_cpu_notifier); - spin_lock_irqsave(&cpufreq_driver_lock, flags); + write_lock_irqsave(&cpufreq_driver_lock, flags); cpufreq_driver = NULL; - spin_unlock_irqrestore(&cpufreq_driver_lock, flags); + write_unlock_irqrestore(&cpufreq_driver_lock, flags); return 0; } -- 1.8.0.1