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Date: Mon, 1 Apr 2013 15:11:09 -0500
From: Nathan Zimmer <nzimmer@....com>
To: viresh.kumar@...aro.org, rjw@...k.pl
Cc: cpufreq@...r.kernel.org, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org, Nathan Zimmer <nzimmer@....com>
Subject: [PATCH v6 2/2] cpufreq: covert the cpufreq_data_lock to a spinlock
This eliminates the rest of the contention found in __cpufreq_cpu_get.
I am not seeing a way to use the rcu so we will have to make due with a
rwlock for now.
Cc: Viresh Kumar <viresh.kumar@...aro.org>
Cc: "Rafael J. Wysocki" <rjw@...k.pl>
Signed-off-by: Nathan Zimmer <nzimmer@....com>
---
drivers/cpufreq/cpufreq.c | 38 +++++++++++++++++++-------------------
1 file changed, 19 insertions(+), 19 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 5139eab..7438c34 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -42,7 +42,7 @@
static struct cpufreq_driver __rcu *cpufreq_driver;
static DEFINE_SPINLOCK(cpufreq_driver_lock);
-static DEFINE_SPINLOCK(cpufreq_data_lock);
+static DEFINE_RWLOCK(cpufreq_data_lock);
static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
#ifdef CONFIG_HOTPLUG_CPU
/* This one keeps track of the previously set governor of a removed CPU */
@@ -150,7 +150,7 @@ static struct cpufreq_policy *__cpufreq_cpu_get(unsigned int cpu, bool sysfs)
goto err_out_unlock;
/* get the CPU */
- spin_lock_irqsave(&cpufreq_data_lock, flags);
+ read_lock_irqsave(&cpufreq_data_lock, flags);
data = per_cpu(cpufreq_cpu_data, cpu);
if (!data)
@@ -159,13 +159,13 @@ 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_data_lock, flags);
+ read_unlock_irqrestore(&cpufreq_data_lock, flags);
rcu_read_unlock();
return data;
err_out_put_module:
module_put(driver->owner);
- spin_unlock_irqrestore(&cpufreq_data_lock, flags);
+ read_unlock_irqrestore(&cpufreq_data_lock, flags);
err_out_unlock:
rcu_read_unlock();
err_out:
@@ -276,9 +276,9 @@ void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
pr_debug("notification %u of frequency transition to %u kHz\n",
state, freqs->new);
- spin_lock_irqsave(&cpufreq_data_lock, flags);
+ read_lock_irqsave(&cpufreq_data_lock, flags);
policy = per_cpu(cpufreq_cpu_data, freqs->cpu);
- spin_unlock_irqrestore(&cpufreq_data_lock, flags);
+ read_unlock_irqrestore(&cpufreq_data_lock, flags);
switch (state) {
@@ -802,12 +802,12 @@ static int cpufreq_add_dev_interface(unsigned int cpu,
}
rcu_read_unlock();
- spin_lock_irqsave(&cpufreq_data_lock, flags);
+ write_lock_irqsave(&cpufreq_data_lock, flags);
for_each_cpu(j, policy->cpus) {
per_cpu(cpufreq_cpu_data, j) = policy;
per_cpu(cpufreq_policy_cpu, j) = policy->cpu;
}
- spin_unlock_irqrestore(&cpufreq_data_lock, flags);
+ write_unlock_irqrestore(&cpufreq_data_lock, flags);
ret = cpufreq_add_dev_symlink(cpu, policy);
if (ret)
@@ -858,12 +858,12 @@ static int cpufreq_add_policy_cpu(unsigned int cpu, unsigned int sibling,
lock_policy_rwsem_write(sibling);
- spin_lock_irqsave(&cpufreq_data_lock, flags);
+ write_lock_irqsave(&cpufreq_data_lock, flags);
cpumask_set_cpu(cpu, policy->cpus);
per_cpu(cpufreq_policy_cpu, cpu) = policy->cpu;
per_cpu(cpufreq_cpu_data, cpu) = policy;
- spin_unlock_irqrestore(&cpufreq_data_lock, flags);
+ write_unlock_irqrestore(&cpufreq_data_lock, flags);
unlock_policy_rwsem_write(sibling);
@@ -918,15 +918,15 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
#ifdef CONFIG_HOTPLUG_CPU
/* Check if this cpu was hot-unplugged earlier and has siblings */
- spin_lock_irqsave(&cpufreq_data_lock, flags);
+ read_lock_irqsave(&cpufreq_data_lock, flags);
for_each_online_cpu(sibling) {
struct cpufreq_policy *cp = per_cpu(cpufreq_cpu_data, sibling);
if (cp && cpumask_test_cpu(cpu, cp->related_cpus)) {
- spin_unlock_irqrestore(&cpufreq_data_lock, flags);
+ read_unlock_irqrestore(&cpufreq_data_lock, flags);
return cpufreq_add_policy_cpu(cpu, sibling, dev);
}
}
- spin_unlock_irqrestore(&cpufreq_data_lock, flags);
+ read_unlock_irqrestore(&cpufreq_data_lock, flags);
#endif
#endif
@@ -1006,10 +1006,10 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
return 0;
err_out_unregister:
- spin_lock_irqsave(&cpufreq_data_lock, flags);
+ write_lock_irqsave(&cpufreq_data_lock, flags);
for_each_cpu(j, policy->cpus)
per_cpu(cpufreq_cpu_data, j) = NULL;
- spin_unlock_irqrestore(&cpufreq_data_lock, flags);
+ write_unlock_irqrestore(&cpufreq_data_lock, flags);
kobject_put(&policy->kobj);
wait_for_completion(&policy->kobj_unregister);
@@ -1067,12 +1067,12 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
pr_debug("%s: unregistering CPU %u\n", __func__, cpu);
- spin_lock_irqsave(&cpufreq_data_lock, flags);
+ write_lock_irqsave(&cpufreq_data_lock, flags);
data = per_cpu(cpufreq_cpu_data, cpu);
per_cpu(cpufreq_cpu_data, cpu) = NULL;
- spin_unlock_irqrestore(&cpufreq_data_lock, flags);
+ write_unlock_irqrestore(&cpufreq_data_lock, flags);
if (!data) {
pr_debug("%s: No cpu_data found\n", __func__);
@@ -1111,9 +1111,9 @@ static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif
WARN_ON(lock_policy_rwsem_write(cpu));
cpumask_set_cpu(cpu, data->cpus);
- spin_lock_irqsave(&cpufreq_data_lock, flags);
+ write_lock_irqsave(&cpufreq_data_lock, flags);
per_cpu(cpufreq_cpu_data, cpu) = data;
- spin_unlock_irqrestore(&cpufreq_data_lock, flags);
+ write_unlock_irqrestore(&cpufreq_data_lock, flags);
unlock_policy_rwsem_write(cpu);
--
1.8.1.2
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