Commit b8eed8af authored by Viresh Kumar's avatar Viresh Kumar Committed by Rafael J. Wysocki

cpufreq: Simplify __cpufreq_remove_dev()

__cpufreq_remove_dev() is called on multiple occasions: cpufreq_driver
unregister and cpu removals.

Current implementation of this routine is overly complex without much need. If
the cpu to be removed is the policy->cpu, we remove the policy first and add all
other cpus again from policy->cpus and then finally call __cpufreq_remove_dev()
again to remove the cpu to be deleted. Haahhhh..

There exist a simple solution to removal of a cpu:
- Simply use the old policy structure
- update its fields like: policy->cpu, etc.
- notify any users of cpufreq, which depend on changing policy->cpu

Hence this patch, which tries to implement the above theory. It is tested well
by myself on ARM big.LITTLE TC2 SoC, which has 5 cores (2 A15 and 3 A7). Both
A15's share same struct policy and all A7's share same policy structure.
Signed-off-by: default avatarViresh Kumar <viresh.kumar@linaro.org>
Tested-by: default avatarShawn Guo <shawn.guo@linaro.org>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent f8517804
......@@ -1036,6 +1036,25 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
return ret;
}
static void update_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu)
{
int j;
policy->last_cpu = policy->cpu;
policy->cpu = cpu;
for_each_cpu(j, policy->cpus) {
if (!cpu_online(j))
continue;
per_cpu(cpufreq_policy_cpu, j) = cpu;
}
#ifdef CONFIG_CPU_FREQ_TABLE
cpufreq_frequency_table_update_policy_cpu(policy);
#endif
blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
CPUFREQ_UPDATE_POLICY_CPU, policy);
}
/**
* __cpufreq_remove_dev - remove a CPU device
......@@ -1046,132 +1065,92 @@ static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
*/
static int __cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
{
unsigned int cpu = dev->id;
unsigned int cpu = dev->id, ret, cpus;
unsigned long flags;
struct cpufreq_policy *data;
struct kobject *kobj;
struct completion *cmp;
#ifdef CONFIG_SMP
struct device *cpu_dev;
unsigned int j;
#endif
pr_debug("unregistering CPU %u\n", cpu);
pr_debug("%s: unregistering CPU %u\n", __func__, cpu);
spin_lock_irqsave(&cpufreq_driver_lock, flags);
data = per_cpu(cpufreq_cpu_data, cpu);
if (!data) {
pr_debug("%s: No cpu_data found\n", __func__);
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
unlock_policy_rwsem_write(cpu);
return -EINVAL;
}
per_cpu(cpufreq_cpu_data, cpu) = NULL;
#ifdef CONFIG_SMP
/* if this isn't the CPU which is the parent of the kobj, we
* only need to unlink, put and exit
*/
if (unlikely(cpu != data->cpu)) {
pr_debug("removing link\n");
if (cpufreq_driver->target)
__cpufreq_governor(data, CPUFREQ_GOV_STOP);
cpumask_clear_cpu(cpu, data->cpus);
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
__cpufreq_governor(data, CPUFREQ_GOV_START);
__cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
kobj = &dev->kobj;
cpufreq_cpu_put(data);
unlock_policy_rwsem_write(cpu);
sysfs_remove_link(kobj, "cpufreq");
return 0;
}
#endif
#ifdef CONFIG_SMP
#ifdef CONFIG_HOTPLUG_CPU
strncpy(per_cpu(cpufreq_cpu_governor, cpu), data->governor->name,
CPUFREQ_NAME_LEN);
#endif
/* if we have other CPUs still registered, we need to unlink them,
* or else wait_for_completion below will lock up. Clean the
* per_cpu(cpufreq_cpu_data) while holding the lock, and remove
* the sysfs links afterwards.
*/
if (unlikely(cpumask_weight(data->cpus) > 1)) {
for_each_cpu(j, data->cpus) {
if (j == cpu)
continue;
per_cpu(cpufreq_cpu_data, j) = NULL;
}
}
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
per_cpu(cpufreq_cpu_data, cpu) = NULL;
cpus = cpumask_weight(data->cpus);
cpumask_clear_cpu(cpu, data->cpus);
if (unlikely(cpumask_weight(data->cpus) > 1)) {
for_each_cpu(j, data->cpus) {
if (j == cpu)
continue;
pr_debug("removing link for cpu %u\n", j);
#ifdef CONFIG_HOTPLUG_CPU
strncpy(per_cpu(cpufreq_cpu_governor, j),
data->governor->name, CPUFREQ_NAME_LEN);
#endif
cpu_dev = get_cpu_device(j);
kobj = &cpu_dev->kobj;
if (unlikely((cpu == data->cpu) && (cpus > 1))) {
/* first sibling now owns the new sysfs dir */
cpu_dev = get_cpu_device(cpumask_first(data->cpus));
sysfs_remove_link(&cpu_dev->kobj, "cpufreq");
ret = kobject_move(&data->kobj, &cpu_dev->kobj);
if (ret) {
pr_err("%s: Failed to move kobj: %d", __func__, ret);
cpumask_set_cpu(cpu, data->cpus);
ret = sysfs_create_link(&cpu_dev->kobj, &data->kobj,
"cpufreq");
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
unlock_policy_rwsem_write(cpu);
sysfs_remove_link(kobj, "cpufreq");
lock_policy_rwsem_write(cpu);
cpufreq_cpu_put(data);
return -EINVAL;
}
update_policy_cpu(data, cpu_dev->id);
pr_debug("%s: policy Kobject moved to cpu: %d from: %d\n",
__func__, cpu_dev->id, cpu);
}
#else
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
#endif
if (cpufreq_driver->target)
__cpufreq_governor(data, CPUFREQ_GOV_STOP);
spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
kobj = &data->kobj;
cmp = &data->kobj_unregister;
pr_debug("%s: removing link, cpu: %d\n", __func__, cpu);
cpufreq_cpu_put(data);
unlock_policy_rwsem_write(cpu);
kobject_put(kobj);
sysfs_remove_link(&dev->kobj, "cpufreq");
/* we need to make sure that the underlying kobj is actually
* not referenced anymore by anybody before we proceed with
* unloading.
*/
pr_debug("waiting for dropping of refcount\n");
wait_for_completion(cmp);
pr_debug("wait complete\n");
lock_policy_rwsem_write(cpu);
if (cpufreq_driver->exit)
cpufreq_driver->exit(data);
unlock_policy_rwsem_write(cpu);
/* If cpu is last user of policy, free policy */
if (cpus == 1) {
lock_policy_rwsem_write(cpu);
kobj = &data->kobj;
cmp = &data->kobj_unregister;
unlock_policy_rwsem_write(cpu);
kobject_put(kobj);
#ifdef CONFIG_HOTPLUG_CPU
/* when the CPU which is the parent of the kobj is hotplugged
* offline, check for siblings, and create cpufreq sysfs interface
* and symlinks
*/
if (unlikely(cpumask_weight(data->cpus) > 1)) {
/* first sibling now owns the new sysfs dir */
cpumask_clear_cpu(cpu, data->cpus);
cpufreq_add_dev(get_cpu_device(cpumask_first(data->cpus)), NULL);
/* we need to make sure that the underlying kobj is actually
* not referenced anymore by anybody before we proceed with
* unloading.
*/
pr_debug("waiting for dropping of refcount\n");
wait_for_completion(cmp);
pr_debug("wait complete\n");
/* finally remove our own symlink */
lock_policy_rwsem_write(cpu);
__cpufreq_remove_dev(dev, sif);
}
#endif
if (cpufreq_driver->exit)
cpufreq_driver->exit(data);
unlock_policy_rwsem_write(cpu);
free_cpumask_var(data->related_cpus);
free_cpumask_var(data->cpus);
kfree(data);
free_cpumask_var(data->related_cpus);
free_cpumask_var(data->cpus);
kfree(data);
} else if (cpufreq_driver->target) {
__cpufreq_governor(data, CPUFREQ_GOV_START);
__cpufreq_governor(data, CPUFREQ_GOV_LIMITS);
}
return 0;
}
......
......@@ -170,11 +170,13 @@ static int freq_table_get_index(struct cpufreq_stats *stat, unsigned int freq)
static void cpufreq_stats_free_table(unsigned int cpu)
{
struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table, cpu);
if (stat) {
pr_debug("%s: Free stat table\n", __func__);
kfree(stat->time_in_state);
kfree(stat);
per_cpu(cpufreq_stats_table, cpu) = NULL;
}
per_cpu(cpufreq_stats_table, cpu) = NULL;
}
/* must be called early in the CPU removal sequence (before
......@@ -183,8 +185,10 @@ static void cpufreq_stats_free_table(unsigned int cpu)
static void cpufreq_stats_free_sysfs(unsigned int cpu)
{
struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
if (policy && policy->cpu == cpu)
if (policy && (cpumask_weight(policy->cpus) == 1)) {
pr_debug("%s: Free sysfs stat\n", __func__);
sysfs_remove_group(&policy->kobj, &stats_attr_group);
}
if (policy)
cpufreq_cpu_put(policy);
}
......@@ -262,6 +266,19 @@ static int cpufreq_stats_create_table(struct cpufreq_policy *policy,
return ret;
}
static void cpufreq_stats_update_policy_cpu(struct cpufreq_policy *policy)
{
struct cpufreq_stats *stat = per_cpu(cpufreq_stats_table,
policy->last_cpu);
pr_debug("Updating stats_table for new_cpu %u from last_cpu %u\n",
policy->cpu, policy->last_cpu);
per_cpu(cpufreq_stats_table, policy->cpu) = per_cpu(cpufreq_stats_table,
policy->last_cpu);
per_cpu(cpufreq_stats_table, policy->last_cpu) = NULL;
stat->cpu = policy->cpu;
}
static int cpufreq_stat_notifier_policy(struct notifier_block *nb,
unsigned long val, void *data)
{
......@@ -269,6 +286,12 @@ static int cpufreq_stat_notifier_policy(struct notifier_block *nb,
struct cpufreq_policy *policy = data;
struct cpufreq_frequency_table *table;
unsigned int cpu = policy->cpu;
if (val == CPUFREQ_UPDATE_POLICY_CPU) {
cpufreq_stats_update_policy_cpu(policy);
return 0;
}
if (val != CPUFREQ_NOTIFY)
return 0;
table = cpufreq_frequency_get_table(cpu);
......
......@@ -227,6 +227,15 @@ void cpufreq_frequency_table_put_attr(unsigned int cpu)
}
EXPORT_SYMBOL_GPL(cpufreq_frequency_table_put_attr);
void cpufreq_frequency_table_update_policy_cpu(struct cpufreq_policy *policy)
{
pr_debug("Updating show_table for new_cpu %u from last_cpu %u\n",
policy->cpu, policy->last_cpu);
per_cpu(cpufreq_show_table, policy->cpu) = per_cpu(cpufreq_show_table,
policy->last_cpu);
per_cpu(cpufreq_show_table, policy->last_cpu) = NULL;
}
struct cpufreq_frequency_table *cpufreq_frequency_get_table(unsigned int cpu)
{
return per_cpu(cpufreq_show_table, cpu);
......
......@@ -93,7 +93,9 @@ struct cpufreq_policy {
cpumask_var_t related_cpus; /* CPUs with any coordination */
unsigned int shared_type; /* ANY or ALL affected CPUs
should set cpufreq */
unsigned int cpu; /* cpu nr of registered CPU */
unsigned int cpu; /* cpu nr of CPU managing this policy */
unsigned int last_cpu; /* cpu nr of previous CPU that managed
* this policy */
struct cpufreq_cpuinfo cpuinfo;/* see above */
unsigned int min; /* in kHz */
......@@ -112,10 +114,11 @@ struct cpufreq_policy {
struct completion kobj_unregister;
};
#define CPUFREQ_ADJUST (0)
#define CPUFREQ_INCOMPATIBLE (1)
#define CPUFREQ_NOTIFY (2)
#define CPUFREQ_START (3)
#define CPUFREQ_ADJUST (0)
#define CPUFREQ_INCOMPATIBLE (1)
#define CPUFREQ_NOTIFY (2)
#define CPUFREQ_START (3)
#define CPUFREQ_UPDATE_POLICY_CPU (4)
#define CPUFREQ_SHARED_TYPE_NONE (0) /* None */
#define CPUFREQ_SHARED_TYPE_HW (1) /* HW does needed coordination */
......@@ -405,6 +408,7 @@ extern struct freq_attr cpufreq_freq_attr_scaling_available_freqs;
void cpufreq_frequency_table_get_attr(struct cpufreq_frequency_table *table,
unsigned int cpu);
void cpufreq_frequency_table_update_policy_cpu(struct cpufreq_policy *policy);
void cpufreq_frequency_table_put_attr(unsigned int cpu);
#endif /* _LINUX_CPUFREQ_H */
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