Preliminary patch. Not tested. Just sending out to give an idea of what I'm
looking to do. Expect a lot more simplification when it's done.
Benefits:
* A lot more simpler code.
* Less stability issues.
* Suspend/resume time would improve.
* Hotplug time would improve.
* Sysfs file permissions would be maintained.
* More policy settings would be maintained across suspend/resume.
* cpufreq stats would be maintained across hotplug for all CPUs.
Change-Id: I39c395e1fee8731880c0fd7c8a9c1d83e2e4b8d0
Signed-off-by: Saravana Kannan <skan...@codeaurora.org>
---
drivers/cpufreq/cpufreq.c | 293 +++++++++-------------------------------------
1 file changed, 55 insertions(+), 238 deletions(-)
diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index 62259d2..8ca1b6f 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -859,13 +859,13 @@ void cpufreq_sysfs_remove_file(const struct attribute
*attr)
}
EXPORT_SYMBOL(cpufreq_sysfs_remove_file);
-/* symlink affected CPUs */
+/* symlink related CPUs */
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->cpu)
@@ -881,12 +881,16 @@ static int cpufreq_add_dev_symlink(struct cpufreq_policy
*policy)
return ret;
}
-static int cpufreq_add_dev_interface(struct cpufreq_policy *policy,
- struct device *dev)
+static int cpufreq_add_dev_interface(struct cpufreq_policy *policy)
{
struct freq_attr **drv_attr;
+ struct device *dev;
int ret = 0;
+ dev = get_cpu_device(policy->cpu);
+ if (!dev)
+ return -EINVAL;
+
/* prepare interface data */
ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
&dev->kobj, "cpufreq");
@@ -961,12 +965,13 @@ static void cpufreq_init_policy(struct cpufreq_policy
*policy)
}
#ifdef CONFIG_HOTPLUG_CPU
-static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy,
- unsigned int cpu, struct device *dev)
+static int cpufreq_change_policy_cpus(struct cpufreq_policy *policy,
+ unsigned int cpu, bool add)
{
int ret = 0;
unsigned long flags;
+ /* FIXME: Don't send START/STOP when going from/to 0 cpus */
if (has_target()) {
ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
if (ret) {
@@ -979,7 +984,11 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy
*policy,
write_lock_irqsave(&cpufreq_driver_lock, flags);
- cpumask_set_cpu(cpu, policy->cpus);
+ if (add)
+ cpumask_set_cpu(cpu, policy->cpus);
+ else
+ cpumask_clear_cpu(cpu, policy->cpus);
+
per_cpu(cpufreq_cpu_data, cpu) = policy;
write_unlock_irqrestore(&cpufreq_driver_lock, flags);
@@ -995,27 +1004,9 @@ static int cpufreq_add_policy_cpu(struct cpufreq_policy
*policy,
return ret;
}
}
-
- return sysfs_create_link(&dev->kobj, &policy->kobj, "cpufreq");
}
#endif
-static struct cpufreq_policy *cpufreq_policy_restore(unsigned int cpu)
-{
- struct cpufreq_policy *policy;
- unsigned long flags;
-
- read_lock_irqsave(&cpufreq_driver_lock, flags);
-
- policy = per_cpu(cpufreq_cpu_data_fallback, cpu);
-
- read_unlock_irqrestore(&cpufreq_driver_lock, flags);
-
- policy->governor = NULL;
-
- return policy;
-}
-
static struct cpufreq_policy *cpufreq_policy_alloc(void)
{
struct cpufreq_policy *policy;
@@ -1076,22 +1067,6 @@ static void cpufreq_policy_free(struct cpufreq_policy
*policy)
kfree(policy);
}
-static void update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu)
-{
- if (WARN_ON(cpu == policy->cpu))
- return;
-
- down_write(&policy->rwsem);
-
- policy->last_cpu = policy->cpu;
- policy->cpu = cpu;
-
- up_write(&policy->rwsem);
-
- blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
- CPUFREQ_UPDATE_POLICY_CPU, policy);
-}
-
static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
{
unsigned int j, cpu = dev->id;
@@ -1111,55 +1086,28 @@ static int __cpufreq_add_dev(struct device *dev, struct
subsys_interface *sif)
#ifdef CONFIG_SMP
/* check whether a different CPU already registered this
* CPU because it is in the same boat. */
+ /* FIXME: This probably needs fixing to avoid "try lock" from
+ * returning NULL. Also, change to likely() */
policy = cpufreq_cpu_get(cpu);
if (unlikely(policy)) {
+ cpufreq_change_policy_cpus(policy, cpu, true);
cpufreq_cpu_put(policy);
return 0;
}
#endif
+ /* FIXME: Is returning 0 the right thing to do?! Existing code */
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
-
- /*
- * Restore the saved policy when doing light-weight init and fall back
- * to the full init if that fails.
- */
- policy = recover_policy ? cpufreq_policy_restore(cpu) : NULL;
- if (!policy) {
- recover_policy = false;
- policy = cpufreq_policy_alloc();
- if (!policy)
- goto nomem_out;
- }
-
- /*
- * In the resume path, since we restore a saved policy, the assignment
- * to policy->cpu is like an update of the existing policy, rather than
- * the creation of a brand new one. So we need to perform this update
- * by invoking update_policy_cpu().
- */
- if (recover_policy && cpu != policy->cpu)
- update_policy_cpu(policy, cpu);
- else
- policy->cpu = cpu;
+ /* If we get this far, this is the first time we are adding the
+ * policy */
+ policy = cpufreq_policy_alloc();
+ if (!policy)
+ goto nomem_out;
+ policy->cpu = cpu;
cpumask_copy(policy->cpus, cpumask_of(cpu));
-
init_completion(&policy->kobj_unregister);
INIT_WORK(&policy->update, handle_update);
@@ -1175,20 +1123,23 @@ static int __cpufreq_add_dev(struct device *dev, struct
subsys_interface *sif)
/* related cpus should atleast have policy->cpus */
cpumask_or(policy->related_cpus, policy->related_cpus, policy->cpus);
+ /* Weed out impossible CPUs. */
+ cpumask_and(policy->related_cpus, policy->related_cpus,
+ cpu_possible_mask);
+
+ /* Just make the first CPU in the policy as the permanent owner of
+ * the sysfs nodes. It doesn't need to be online to host the nodes */
+ policy->cpu = cpumask_first(policy->related_cpus);
+
/*
* affected cpus must always be the one, which are online. We aren't
* managing offline cpus here.
*/
cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);
- if (!recover_policy) {
- policy->user_policy.min = policy->min;
- policy->user_policy.max = policy->max;
- }
-
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);
@@ -1243,13 +1194,11 @@ static int __cpufreq_add_dev(struct device *dev, struct
subsys_interface *sif)
blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
CPUFREQ_START, policy);
- if (!recover_policy) {
- ret = cpufreq_add_dev_interface(policy, dev);
- if (ret)
- goto err_out_unregister;
- blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
- CPUFREQ_CREATE_POLICY, policy);
- }
+ ret = cpufreq_add_dev_interface(policy);
+ if (ret)
+ goto err_out_unregister;
+ blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+ CPUFREQ_CREATE_POLICY, policy);
write_lock_irqsave(&cpufreq_driver_lock, flags);
list_add(&policy->policy_list, &cpufreq_policy_list);
@@ -1257,10 +1206,6 @@ static int __cpufreq_add_dev(struct device *dev, struct
subsys_interface *sif)
cpufreq_init_policy(policy);
- if (!recover_policy) {
- policy->user_policy.policy = policy->policy;
- policy->user_policy.governor = policy->governor;
- }
up_write(&policy->rwsem);
kobject_uevent(&policy->kobj, KOBJ_ADD);
@@ -1307,161 +1252,43 @@ static int cpufreq_add_dev(struct device *dev, struct
subsys_interface *sif)
return __cpufreq_add_dev(dev, sif);
}
-static int cpufreq_nominate_new_policy_cpu(struct cpufreq_policy *policy,
- unsigned int old_cpu)
-{
- struct device *cpu_dev;
- int ret;
-
- /* first sibling now owns the new sysfs dir */
- cpu_dev = get_cpu_device(cpumask_any_but(policy->cpus, old_cpu));
-
- sysfs_remove_link(&cpu_dev->kobj, "cpufreq");
- ret = kobject_move(&policy->kobj, &cpu_dev->kobj);
- if (ret) {
- pr_err("%s: Failed to move kobj: %d\n", __func__, ret);
-
- down_write(&policy->rwsem);
- cpumask_set_cpu(old_cpu, policy->cpus);
- up_write(&policy->rwsem);
-
- ret = sysfs_create_link(&cpu_dev->kobj, &policy->kobj,
- "cpufreq");
-
- return -EINVAL;
- }
-
- return cpu_dev->id;
-}
-
-static int __cpufreq_remove_dev_prepare(struct device *dev,
- struct subsys_interface *sif)
+static int __cpufreq_remove_dev(struct device *dev,
+ struct subsys_interface *sif)
{
unsigned int cpu = dev->id, cpus;
- int new_cpu, ret;
+ int ret;
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__);
return -EINVAL;
}
- if (has_target()) {
- ret = __cpufreq_governor(policy, CPUFREQ_GOV_STOP);
- if (ret) {
- pr_err("%s: Failed to stop governor\n", __func__);
- return ret;
- }
- }
-
- if (!cpufreq_driver->setpolicy)
- strncpy(per_cpu(cpufreq_cpu_governor, cpu),
- policy->governor->name, CPUFREQ_NAME_LEN);
+#ifdef CONFIG_HOTPLUG_CPU
+ ret = cpufreq_change_policy_cpus(policy, cpu, false);
+ /* FIXME: Handle error */
+#endif
+ /* FIXME: This stuff below would get pulled into change_policy_cpus.
+ * Keeping it here just for the RFC diff to be easy to read. */
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);
- }
- } else if (cpufreq_driver->stop_cpu && cpufreq_driver->setpolicy) {
+ if (cpus < 1 && cpufreq_driver->stop_cpu && cpufreq_driver->setpolicy) {
cpufreq_driver->stop_cpu(policy);
}
return 0;
}
-static int __cpufreq_remove_dev_finish(struct device *dev,
- struct subsys_interface *sif)
-{
- unsigned int cpu = dev->id, cpus;
- int ret;
- unsigned long flags;
- struct cpufreq_policy *policy;
-
- read_lock_irqsave(&cpufreq_driver_lock, flags);
- policy = per_cpu(cpufreq_cpu_data, cpu);
- read_unlock_irqrestore(&cpufreq_driver_lock, flags);
-
- if (!policy) {
- pr_debug("%s: No cpu_data found\n", __func__);
- return -EINVAL;
- }
-
- down_write(&policy->rwsem);
- cpus = cpumask_weight(policy->cpus);
-
- if (cpus > 1)
- cpumask_clear_cpu(cpu, policy->cpus);
- up_write(&policy->rwsem);
-
- /* If cpu is last user of policy, free policy */
- if (cpus == 1) {
- if (has_target()) {
- ret = __cpufreq_governor(policy,
- CPUFREQ_GOV_POLICY_EXIT);
- if (ret) {
- pr_err("%s: Failed to exit governor\n",
- __func__);
- return ret;
- }
- }
-
- if (!cpufreq_suspended)
- cpufreq_policy_put_kobj(policy);
-
- /*
- * Perform the ->exit() even during light-weight tear-down,
- * since this is a core component, and is essential for the
- * subsequent light-weight ->init() to succeed.
- */
- if (cpufreq_driver->exit)
- cpufreq_driver->exit(policy);
-
- /* Remove policy from list of active policies */
- write_lock_irqsave(&cpufreq_driver_lock, flags);
- list_del(&policy->policy_list);
- write_unlock_irqrestore(&cpufreq_driver_lock, flags);
-
- if (!cpufreq_suspended)
- cpufreq_policy_free(policy);
- } else if (has_target()) {
- ret = __cpufreq_governor(policy, CPUFREQ_GOV_START);
- if (!ret)
- ret = __cpufreq_governor(policy, CPUFREQ_GOV_LIMITS);
-
- if (ret) {
- pr_err("%s: Failed to start governor\n", __func__);
- return ret;
- }
- }
-
- per_cpu(cpufreq_cpu_data, cpu) = NULL;
- return 0;
-}
-
/**
* cpufreq_remove_dev - remove a CPU device
*
@@ -1475,10 +1302,7 @@ static int cpufreq_remove_dev(struct device *dev, struct
subsys_interface *sif)
if (cpu_is_offline(cpu))
return 0;
- ret = __cpufreq_remove_dev_prepare(dev, sif);
-
- if (!ret)
- ret = __cpufreq_remove_dev_finish(dev, sif);
+ ret = __cpufreq_remove_dev(dev, sif);
return ret;
}
@@ -2295,19 +2119,12 @@ static int cpufreq_cpu_callback(struct notifier_block
*nfb,
if (dev) {
switch (action & ~CPU_TASKS_FROZEN) {
case CPU_ONLINE:
+ case CPU_DOWN_FAILED:
__cpufreq_add_dev(dev, NULL);
break;
case CPU_DOWN_PREPARE:
- __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);
+ __cpufreq_remove_dev(dev, NULL);
break;
}
}
--
1.8.2.1
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