[RFC][PATCH 1/4] Clean up cpufreq hot-cpu callback.

From: Gautham R Shenoy
Date: Thu Aug 24 2006 - 06:24:37 EST


--
Gautham R Shenoy
Linux Technology Center
IBM India.
"Freedom comes with a price tag of responsibility, which is still a bargain,
because Freedom is priceless!"
This patch cleans up the hot-cpu callback interface of cpufreq so that
lock_cpu_hotplug won't be called from a cpu_up or a cpu_down.

Signed-off-by : Gautham R Shenoy <ego@xxxxxxxxxx>

Index: current/include/linux/cpufreq.h
===================================================================
--- current.orig/include/linux/cpufreq.h 2006-08-06 23:50:11.000000000 +0530
+++ current/include/linux/cpufreq.h 2006-08-24 14:59:59.000000000 +0530
@@ -164,6 +164,9 @@ struct cpufreq_governor {

/* pass a target to the cpufreq driver
*/
+extern int cpufreq_driver_target_cpulocked(struct cpufreq_policy *policy,
+ unsigned int target_freq,
+ unsigned int relation);
extern int cpufreq_driver_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation);
@@ -253,8 +256,10 @@ struct freq_attr {
* CPUFREQ 2.6. INTERFACE *
*********************************************************************/
int cpufreq_set_policy(struct cpufreq_policy *policy);
+int cpufreq_set_policy_cpulocked(struct cpufreq_policy *policy);
int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu);
int cpufreq_update_policy(unsigned int cpu);
+int cpufreq_update_policy_cpulocked(unsigned int cpu);

/* query the current CPU frequency (in kHz). If zero, cpufreq couldn't detect it */
unsigned int cpufreq_get(unsigned int cpu);
Index: current/drivers/cpufreq/cpufreq.c
===================================================================
--- current.orig/drivers/cpufreq/cpufreq.c 2006-08-06 23:50:11.000000000 +0530
+++ current/drivers/cpufreq/cpufreq.c 2006-08-24 14:59:59.000000000 +0530
@@ -744,7 +744,7 @@ static int cpufreq_add_dev (struct sys_d
mutex_unlock(&policy->lock);

/* set default policy */
- ret = cpufreq_set_policy(&new_policy);
+ ret = cpufreq_set_policy_cpulocked(&new_policy);
if (ret) {
dprintk("setting policy failed\n");
goto err_out_unregister;
@@ -1246,27 +1246,37 @@ int __cpufreq_driver_target(struct cpufr
EXPORT_SYMBOL_GPL(__cpufreq_driver_target);

int cpufreq_driver_target(struct cpufreq_policy *policy,
+ unsigned int target_freq,
+ unsigned int relation)
+{
+ int ret=0;
+ lock_cpu_hotplug();
+ ret= cpufreq_driver_target_cpulocked(policy,target_freq,relation);
+ unlock_cpu_hotplug();
+ return ret;
+}
+EXPORT_SYMBOL_GPL(cpufreq_driver_target);
+
+int cpufreq_driver_target_cpulocked(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
- int ret;
+ int ret=0;

policy = cpufreq_cpu_get(policy->cpu);
if (!policy)
return -EINVAL;

- lock_cpu_hotplug();
mutex_lock(&policy->lock);

ret = __cpufreq_driver_target(policy, target_freq, relation);

mutex_unlock(&policy->lock);
- unlock_cpu_hotplug();

cpufreq_cpu_put(policy);
return ret;
}
-EXPORT_SYMBOL_GPL(cpufreq_driver_target);
+EXPORT_SYMBOL_GPL(cpufreq_driver_target_cpulocked);

/*
* Locking: Must be called with the lock_cpu_hotplug() lock held
@@ -1450,6 +1460,15 @@ error_out:
*/
int cpufreq_set_policy(struct cpufreq_policy *policy)
{
+ int ret=0;
+ lock_cpu_hotplug();
+ ret = cpufreq_set_policy_cpulocked(policy);
+ unlock_cpu_hotplug();
+ return ret;
+}
+
+int cpufreq_set_policy_cpulocked(struct cpufreq_policy *policy)
+{
int ret = 0;
struct cpufreq_policy *data;

@@ -1460,7 +1479,6 @@ int cpufreq_set_policy(struct cpufreq_po
if (!data)
return -EINVAL;

- lock_cpu_hotplug();

/* lock this CPU */
mutex_lock(&data->lock);
@@ -1473,7 +1491,6 @@ int cpufreq_set_policy(struct cpufreq_po

mutex_unlock(&data->lock);

- unlock_cpu_hotplug();
cpufreq_cpu_put(data);

return ret;
@@ -1482,13 +1499,15 @@ EXPORT_SYMBOL(cpufreq_set_policy);


/**
- * cpufreq_update_policy - re-evaluate an existing cpufreq policy
+ * cpufreq_update_policy_cpulocked - re-evaluate an existing cpufreq
+ * policy.
+ * To be called with lock_cpu_hotplug() held.
* @cpu: CPU which shall be re-evaluated
*
* Usefull for policy notifiers which have different necessities
* at different times.
*/
-int cpufreq_update_policy(unsigned int cpu)
+int cpufreq_update_policy_cpulocked(unsigned int cpu)
{
struct cpufreq_policy *data = cpufreq_cpu_get(cpu);
struct cpufreq_policy policy;
@@ -1497,7 +1516,6 @@ int cpufreq_update_policy(unsigned int c
if (!data)
return -ENODEV;

- lock_cpu_hotplug();
mutex_lock(&data->lock);

dprintk("updating policy for CPU %u\n", cpu);
@@ -1523,10 +1541,28 @@ int cpufreq_update_policy(unsigned int c
ret = __cpufreq_set_policy(data, &policy);

mutex_unlock(&data->lock);
- unlock_cpu_hotplug();
cpufreq_cpu_put(data);
return ret;
}
+EXPORT_SYMBOL(cpufreq_update_policy_cpulocked);
+
+/**
+ * cpufreq_update_policy - re-evaluate an existing cpufreq
+ * policy.
+ * Must be called with lock_cpu_hotplug() *not* being held.
+ * @cpu: CPU which shall be re-evaluated
+ *
+ * Usefull for policy notifiers which have different necessities
+ * at different times.
+ */
+int cpufreq_update_policy(unsigned int cpu)
+{
+ int ret=0;
+ lock_cpu_hotplug();
+ cpufreq_update_policy_cpulocked(cpu);
+ unlock_cpu_hotplug();
+ return ret;
+}
EXPORT_SYMBOL(cpufreq_update_policy);

#ifdef CONFIG_HOTPLUG_CPU
@@ -1553,8 +1589,8 @@ static int cpufreq_cpu_callback(struct n
*/
policy = cpufreq_cpu_data[cpu];
if (policy) {
- cpufreq_driver_target(policy, policy->min,
- CPUFREQ_RELATION_H);
+ cpufreq_driver_target_cpulocked(policy,
+ policy->min, CPUFREQ_RELATION_H);
}
break;
case CPU_DEAD:
Index: current/drivers/cpufreq/cpufreq_stats.c
===================================================================
--- current.orig/drivers/cpufreq/cpufreq_stats.c 2006-08-06 23:50:11.000000000 +0530
+++ current/drivers/cpufreq/cpufreq_stats.c 2006-08-24 14:59:59.000000000 +0530
@@ -309,7 +309,7 @@ static int cpufreq_stat_cpu_callback(str

switch (action) {
case CPU_ONLINE:
- cpufreq_update_policy(cpu);
+ cpufreq_update_policy_cpulocked(cpu);
break;
case CPU_DEAD:
cpufreq_stats_free_table(cpu);