[PATCH V2] acpi-cpufreq: replace per_cpu with driver_data of policy

[PATCH V2] acpi-cpufreq: replace per_cpu with driver_data of policy

[Pan Xinhui]

Drivers can store their internal per-policy information in
policy->driver_data, lets use it.

we have benefits after this replacing.
1) memory saving.
2) policy is shared by several cpus, per_cpu seems not correct. using
*driver_data* is more reasonable.
3) fix a memory leak in acpi_cpufreq_cpu_exit. as policy->cpu might
change during cpu hotplug. So sometimes we cant't free *data*, use
*driver_data* to fix it.
4) fix a zero return value of get_cur_freq_on_cpu. Only per_cpu of
policy->cpu is set to *data*, if we try to get cpufreq on other cpus, we
get zero instead of correct values. Use *driver_data* to fix it.

Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com>
---
Changes from V1:
	codes style fix, comments update
	move cpufreq_cpu_put(policy) after we get *driver_data*
---
 drivers/cpufreq/acpi-cpufreq.c | 40 ++++++++++++++++++++++------------------
 1 file changed, 22 insertions(+), 18 deletions(-)

diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
index 0136dfc..e7fcaa6 100644
--- a/drivers/cpufreq/acpi-cpufreq.c
+++ b/drivers/cpufreq/acpi-cpufreq.c
@@ -72,8 +72,6 @@ struct acpi_cpufreq_data {
 	cpumask_var_t freqdomain_cpus;
 };
 
-static DEFINE_PER_CPU(struct acpi_cpufreq_data *, acfreq_data);
-
 /* acpi_perf_data is a pointer to percpu data. */
 static struct acpi_processor_performance __percpu *acpi_perf_data;
 
@@ -144,7 +142,7 @@ static int _store_boost(int val)
 
 static ssize_t show_freqdomain_cpus(struct cpufreq_policy *policy, char *buf)
 {
-	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);
+	struct acpi_cpufreq_data *data = policy->driver_data;
 
 	return cpufreq_show_cpus(data->freqdomain_cpus, buf);
 }
@@ -327,7 +325,8 @@ static void drv_write(struct drv_cmd *cmd)
 	put_cpu();
 }
 
-static u32 get_cur_val(const struct cpumask *mask)
+static u32
+get_cur_val(const struct cpumask *mask, struct acpi_cpufreq_data *data)
 {
 	struct acpi_processor_performance *perf;
 	struct drv_cmd cmd;
@@ -335,7 +334,7 @@ static u32 get_cur_val(const struct cpumask *mask)
 	if (unlikely(cpumask_empty(mask)))
 		return 0;
 
-	switch (per_cpu(acfreq_data, cpumask_first(mask))->cpu_feature) {
+	switch (data->cpu_feature) {
 	case SYSTEM_INTEL_MSR_CAPABLE:
 		cmd.type = SYSTEM_INTEL_MSR_CAPABLE;
 		cmd.addr.msr.reg = MSR_IA32_PERF_CTL;
@@ -346,7 +345,7 @@ static u32 get_cur_val(const struct cpumask *mask)
 		break;
 	case SYSTEM_IO_CAPABLE:
 		cmd.type = SYSTEM_IO_CAPABLE;
-		perf = per_cpu(acfreq_data, cpumask_first(mask))->acpi_data;
+		perf = data->acpi_data;
 		cmd.addr.io.port = perf->control_register.address;
 		cmd.addr.io.bit_width = perf->control_register.bit_width;
 		break;
@@ -364,19 +363,24 @@ static u32 get_cur_val(const struct cpumask *mask)
 
 static unsigned int get_cur_freq_on_cpu(unsigned int cpu)
 {
-	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, cpu);
+	struct acpi_cpufreq_data *data;
+	struct cpufreq_policy *policy;
 	unsigned int freq;
 	unsigned int cached_freq;
 
 	pr_debug("get_cur_freq_on_cpu (%d)\n", cpu);
 
-	if (unlikely(data == NULL ||
-		     data->acpi_data == NULL || data->freq_table == NULL)) {
+	policy = cpufreq_cpu_get(cpu);
+	if (unlikely(!policy))
+		return 0;
+
+	data = policy->driver_data;
+	cpufreq_cpu_put(policy);
+	if (unlikely(!data || !data->acpi_data || !data->freq_table))
 		return 0;
-	}
 
 	cached_freq = data->freq_table[data->acpi_data->state].frequency;
-	freq = extract_freq(get_cur_val(cpumask_of(cpu)), data);
+	freq = extract_freq(get_cur_val(cpumask_of(cpu), data), data);
 	if (freq != cached_freq) {
 		/*
 		 * The dreaded BIOS frequency change behind our back.
@@ -397,7 +401,7 @@ static unsigned int check_freqs(const struct cpumask *mask, unsigned int freq,
 	unsigned int i;
 
 	for (i = 0; i < 100; i++) {
-		cur_freq = extract_freq(get_cur_val(mask), data);
+		cur_freq = extract_freq(get_cur_val(mask, data), data);
 		if (cur_freq == freq)
 			return 1;
 		udelay(10);
@@ -408,7 +412,7 @@ static unsigned int check_freqs(const struct cpumask *mask, unsigned int freq,
 static int acpi_cpufreq_target(struct cpufreq_policy *policy,
 			       unsigned int index)
 {
-	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);
+	struct acpi_cpufreq_data *data = policy->driver_data;
 	struct acpi_processor_performance *perf;
 	struct drv_cmd cmd;
 	unsigned int next_perf_state = 0; /* Index into perf table */
@@ -673,7 +677,7 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
 	}
 
 	data->acpi_data = per_cpu_ptr(acpi_perf_data, cpu);
-	per_cpu(acfreq_data, cpu) = data;
+	policy->driver_data = data;
 
 	if (cpu_has(c, X86_FEATURE_CONSTANT_TSC))
 		acpi_cpufreq_driver.flags |= CPUFREQ_CONST_LOOPS;
@@ -843,19 +847,19 @@ err_free_mask:
 	free_cpumask_var(data->freqdomain_cpus);
 err_free:
 	kfree(data);
-	per_cpu(acfreq_data, cpu) = NULL;
+	policy->driver_data = NULL;
 
 	return result;
 }
 
 static int acpi_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 {
-	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);
+	struct acpi_cpufreq_data *data = policy->driver_data;
 
 	pr_debug("acpi_cpufreq_cpu_exit\n");
 
 	if (data) {
-		per_cpu(acfreq_data, policy->cpu) = NULL;
+		policy->driver_data = NULL;
 		acpi_processor_unregister_performance(data->acpi_data,
 						      policy->cpu);
 		free_cpumask_var(data->freqdomain_cpus);
@@ -868,7 +872,7 @@ static int acpi_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 
 static int acpi_cpufreq_resume(struct cpufreq_policy *policy)
 {
-	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);
+	struct acpi_cpufreq_data *data = policy->driver_data;
 
 	pr_debug("acpi_cpufreq_resume\n");
 
-- 
1.9.1

Re: [PATCH V2] acpi-cpufreq: replace per_cpu with driver_data of policy

[Pan Xinhui]

hi, all
	thanks for reviewing.
any comments or advices are welcome :)
I am OOO tomorrow, so response may arrive later.

thanks
xinhui

On 2015年07月07日 20:43, Pan Xinhui wrote:
> 
> Drivers can store their internal per-policy information in
> policy->driver_data, lets use it.
> 
> we have benefits after this replacing.
> 1) memory saving.
> 2) policy is shared by several cpus, per_cpu seems not correct. using
> *driver_data* is more reasonable.
> 3) fix a memory leak in acpi_cpufreq_cpu_exit. as policy->cpu might
> change during cpu hotplug. So sometimes we cant't free *data*, use
> *driver_data* to fix it.
> 4) fix a zero return value of get_cur_freq_on_cpu. Only per_cpu of
> policy->cpu is set to *data*, if we try to get cpufreq on other cpus, we
> get zero instead of correct values. Use *driver_data* to fix it.
> 
> Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com>
> ---
> Changes from V1:
> 	codes style fix, comments update
> 	move cpufreq_cpu_put(policy) after we get *driver_data*
> ---
>  drivers/cpufreq/acpi-cpufreq.c | 40 ++++++++++++++++++++++------------------
>  1 file changed, 22 insertions(+), 18 deletions(-)
> 
> diff --git a/drivers/cpufreq/acpi-cpufreq.c b/drivers/cpufreq/acpi-cpufreq.c
> index 0136dfc..e7fcaa6 100644
> --- a/drivers/cpufreq/acpi-cpufreq.c
> +++ b/drivers/cpufreq/acpi-cpufreq.c
> @@ -72,8 +72,6 @@ struct acpi_cpufreq_data {
>  	cpumask_var_t freqdomain_cpus;
>  };
>  
> -static DEFINE_PER_CPU(struct acpi_cpufreq_data *, acfreq_data);
> -
>  /* acpi_perf_data is a pointer to percpu data. */
>  static struct acpi_processor_performance __percpu *acpi_perf_data;
>  
> @@ -144,7 +142,7 @@ static int _store_boost(int val)
>  
>  static ssize_t show_freqdomain_cpus(struct cpufreq_policy *policy, char *buf)
>  {
> -	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);
> +	struct acpi_cpufreq_data *data = policy->driver_data;
>  
>  	return cpufreq_show_cpus(data->freqdomain_cpus, buf);
>  }
> @@ -327,7 +325,8 @@ static void drv_write(struct drv_cmd *cmd)
>  	put_cpu();
>  }
>  
> -static u32 get_cur_val(const struct cpumask *mask)
> +static u32
> +get_cur_val(const struct cpumask *mask, struct acpi_cpufreq_data *data)
>  {
>  	struct acpi_processor_performance *perf;
>  	struct drv_cmd cmd;
> @@ -335,7 +334,7 @@ static u32 get_cur_val(const struct cpumask *mask)
>  	if (unlikely(cpumask_empty(mask)))
>  		return 0;
>  
> -	switch (per_cpu(acfreq_data, cpumask_first(mask))->cpu_feature) {
> +	switch (data->cpu_feature) {
>  	case SYSTEM_INTEL_MSR_CAPABLE:
>  		cmd.type = SYSTEM_INTEL_MSR_CAPABLE;
>  		cmd.addr.msr.reg = MSR_IA32_PERF_CTL;
> @@ -346,7 +345,7 @@ static u32 get_cur_val(const struct cpumask *mask)
>  		break;
>  	case SYSTEM_IO_CAPABLE:
>  		cmd.type = SYSTEM_IO_CAPABLE;
> -		perf = per_cpu(acfreq_data, cpumask_first(mask))->acpi_data;
> +		perf = data->acpi_data;
>  		cmd.addr.io.port = perf->control_register.address;
>  		cmd.addr.io.bit_width = perf->control_register.bit_width;
>  		break;
> @@ -364,19 +363,24 @@ static u32 get_cur_val(const struct cpumask *mask)
>  
>  static unsigned int get_cur_freq_on_cpu(unsigned int cpu)
>  {
> -	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, cpu);
> +	struct acpi_cpufreq_data *data;
> +	struct cpufreq_policy *policy;
>  	unsigned int freq;
>  	unsigned int cached_freq;
>  
>  	pr_debug("get_cur_freq_on_cpu (%d)\n", cpu);
>  
> -	if (unlikely(data == NULL ||
> -		     data->acpi_data == NULL || data->freq_table == NULL)) {
> +	policy = cpufreq_cpu_get(cpu);
> +	if (unlikely(!policy))
> +		return 0;
> +
> +	data = policy->driver_data;
> +	cpufreq_cpu_put(policy);
> +	if (unlikely(!data || !data->acpi_data || !data->freq_table))
>  		return 0;
> -	}
>  
>  	cached_freq = data->freq_table[data->acpi_data->state].frequency;
> -	freq = extract_freq(get_cur_val(cpumask_of(cpu)), data);
> +	freq = extract_freq(get_cur_val(cpumask_of(cpu), data), data);
>  	if (freq != cached_freq) {
>  		/*
>  		 * The dreaded BIOS frequency change behind our back.
> @@ -397,7 +401,7 @@ static unsigned int check_freqs(const struct cpumask *mask, unsigned int freq,
>  	unsigned int i;
>  
>  	for (i = 0; i < 100; i++) {
> -		cur_freq = extract_freq(get_cur_val(mask), data);
> +		cur_freq = extract_freq(get_cur_val(mask, data), data);
>  		if (cur_freq == freq)
>  			return 1;
>  		udelay(10);
> @@ -408,7 +412,7 @@ static unsigned int check_freqs(const struct cpumask *mask, unsigned int freq,
>  static int acpi_cpufreq_target(struct cpufreq_policy *policy,
>  			       unsigned int index)
>  {
> -	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);
> +	struct acpi_cpufreq_data *data = policy->driver_data;
>  	struct acpi_processor_performance *perf;
>  	struct drv_cmd cmd;
>  	unsigned int next_perf_state = 0; /* Index into perf table */
> @@ -673,7 +677,7 @@ static int acpi_cpufreq_cpu_init(struct cpufreq_policy *policy)
>  	}
>  
>  	data->acpi_data = per_cpu_ptr(acpi_perf_data, cpu);
> -	per_cpu(acfreq_data, cpu) = data;
> +	policy->driver_data = data;
>  
>  	if (cpu_has(c, X86_FEATURE_CONSTANT_TSC))
>  		acpi_cpufreq_driver.flags |= CPUFREQ_CONST_LOOPS;
> @@ -843,19 +847,19 @@ err_free_mask:
>  	free_cpumask_var(data->freqdomain_cpus);
>  err_free:
>  	kfree(data);
> -	per_cpu(acfreq_data, cpu) = NULL;
> +	policy->driver_data = NULL;
>  
>  	return result;
>  }
>  
>  static int acpi_cpufreq_cpu_exit(struct cpufreq_policy *policy)
>  {
> -	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);
> +	struct acpi_cpufreq_data *data = policy->driver_data;
>  
>  	pr_debug("acpi_cpufreq_cpu_exit\n");
>  
>  	if (data) {
> -		per_cpu(acfreq_data, policy->cpu) = NULL;
> +		policy->driver_data = NULL;
>  		acpi_processor_unregister_performance(data->acpi_data,
>  						      policy->cpu);
>  		free_cpumask_var(data->freqdomain_cpus);
> @@ -868,7 +872,7 @@ static int acpi_cpufreq_cpu_exit(struct cpufreq_policy *policy)
>  
>  static int acpi_cpufreq_resume(struct cpufreq_policy *policy)
>  {
> -	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, policy->cpu);
> +	struct acpi_cpufreq_data *data = policy->driver_data;
>  
>  	pr_debug("acpi_cpufreq_resume\n");
>  
> 

Re: [PATCH V2] acpi-cpufreq: replace per_cpu with driver_data of policy

[Viresh Kumar]

On 07-07-15, 20:43, Pan Xinhui wrote:
> 
> Drivers can store their internal per-policy information in
> policy->driver_data, lets use it.
> 
> we have benefits after this replacing.
> 1) memory saving.
> 2) policy is shared by several cpus, per_cpu seems not correct. using
> *driver_data* is more reasonable.
> 3) fix a memory leak in acpi_cpufreq_cpu_exit. as policy->cpu might
> change during cpu hotplug. So sometimes we cant't free *data*, use
> *driver_data* to fix it.
> 4) fix a zero return value of get_cur_freq_on_cpu. Only per_cpu of
> policy->cpu is set to *data*, if we try to get cpufreq on other cpus, we
> get zero instead of correct values. Use *driver_data* to fix it.
> 
> Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com>
> ---
> Changes from V1:
> 	codes style fix, comments update
> 	move cpufreq_cpu_put(policy) after we get *driver_data*
> ---
>  drivers/cpufreq/acpi-cpufreq.c | 40 ++++++++++++++++++++++------------------
>  1 file changed, 22 insertions(+), 18 deletions(-)

Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

-- 
viresh

Re: [PATCH V2] acpi-cpufreq: replace per_cpu with driver_data of policy

[Dmitry Torokhov]

Hi Pan,

On Tue, Jul 07, 2015 at 08:43:26PM +0800, Pan Xinhui wrote:
> @@ -364,19 +363,24 @@ static u32 get_cur_val(const struct cpumask *mask)
>  
>  static unsigned int get_cur_freq_on_cpu(unsigned int cpu)
>  {
> -	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, cpu);
> +	struct acpi_cpufreq_data *data;
> +	struct cpufreq_policy *policy;
>  	unsigned int freq;
>  	unsigned int cached_freq;
>  
>  	pr_debug("get_cur_freq_on_cpu (%d)\n", cpu);
>  
> -	if (unlikely(data == NULL ||
> -		     data->acpi_data == NULL || data->freq_table == NULL)) {
> +	policy = cpufreq_cpu_get(cpu);
> +	if (unlikely(!policy))
> +		return 0;
> +
> +	data = policy->driver_data;
> +	cpufreq_cpu_put(policy);

If we put policy here can we guarantee that memory pointed to by data
stays valid? Shoudln't we issue cpufreq_cpu_put(policy) after we done
assessing the pointer?

> +	if (unlikely(!data || !data->acpi_data || !data->freq_table))
>  		return 0;
> -	}
>  
>  	cached_freq = data->freq_table[data->acpi_data->state].frequency;
> -	freq = extract_freq(get_cur_val(cpumask_of(cpu)), data);
> +	freq = extract_freq(get_cur_val(cpumask_of(cpu), data), data);
>  	if (freq != cached_freq) {
>  		/*
>  		 * The dreaded BIOS frequency change behind our back.

Thanks.

-- 
Dmitry

Re: [PATCH V2] acpi-cpufreq: replace per_cpu with driver_data of policy

[Viresh Kumar]

Hi Dmitry,

On 07-07-15, 10:11, Dmitry Torokhov wrote:
> > +	data = policy->driver_data;
> > +	cpufreq_cpu_put(policy);
> 
> If we put policy here can we guarantee that memory pointed to by data
> stays valid? Shoudln't we issue cpufreq_cpu_put(policy) after we done
> assessing the pointer?

Ideally yes, you are right. But this was a special case as a callback
of the cpufreq-driver is being called and any such issues must be
handled at the core level, it at all they are relevant.

So probably we can do cpufreq_cpu_put() as soon as we have used it.

-- 
viresh

Re: [PATCH V2] acpi-cpufreq: replace per_cpu with driver_data of policy

[Pan Xinhui]

hi, Dmitry	
	thanks for your reply

On 2015年07月08日 01:11, Dmitry Torokhov wrote:
> Hi Pan,
> 
> On Tue, Jul 07, 2015 at 08:43:26PM +0800, Pan Xinhui wrote:
>> @@ -364,19 +363,24 @@ static u32 get_cur_val(const struct cpumask *mask)
>>  
>>  static unsigned int get_cur_freq_on_cpu(unsigned int cpu)
>>  {
>> -	struct acpi_cpufreq_data *data = per_cpu(acfreq_data, cpu);
>> +	struct acpi_cpufreq_data *data;
>> +	struct cpufreq_policy *policy;
>>  	unsigned int freq;
>>  	unsigned int cached_freq;
>>  
>>  	pr_debug("get_cur_freq_on_cpu (%d)\n", cpu);
>>  
>> -	if (unlikely(data == NULL ||
>> -		     data->acpi_data == NULL || data->freq_table == NULL)) {
>> +	policy = cpufreq_cpu_get(cpu);
>> +	if (unlikely(!policy))
>> +		return 0;
>> +
>> +	data = policy->driver_data;
>> +	cpufreq_cpu_put(policy);
> 
> If we put policy here can we guarantee that memory pointed to by data
> stays valid? Shoudln't we issue cpufreq_cpu_put(policy) after we done
> assessing the pointer?
> 

*driver_data* is used internal by acpi-cpufreq driver. So probably issuing
cpufreq_cpu_put(policy) after we get *driver_data* is OKay.

The worry you have is about the race. we set *driver_data* to NULL then 
free it in ->exit callback while ->get callback is using it.

CPU A                                   CPU B
->get					->exit
data = policy->driver_data;
if (!data ....)
					policy->driver_data = NULL;
					kfree(data);
access data ....

yes, it might happen in real world. As Viresh says, it is more like to be a core level work.
But this race exists in current codes, too. Maybe down_write policy->rwsem can avoid this race(need double check).

thanks for pointing out it. :)

thanks
xinhui

>> +	if (unlikely(!data || !data->acpi_data || !data->freq_table))
>>  		return 0;
>> -	}
>>  
>>  	cached_freq = data->freq_table[data->acpi_data->state].frequency;
>> -	freq = extract_freq(get_cur_val(cpumask_of(cpu)), data);
>> +	freq = extract_freq(get_cur_val(cpumask_of(cpu), data), data);
>>  	if (freq != cached_freq) {
>>  		/*
>>  		 * The dreaded BIOS frequency change behind our back.
> 
> Thanks.
> 

Re: [PATCH V2] acpi-cpufreq: replace per_cpu with driver_data of policy

[Rafael J. Wysocki]

On Tuesday, July 07, 2015 08:04:43 PM Viresh Kumar wrote:
> On 07-07-15, 20:43, Pan Xinhui wrote:
> > 
> > Drivers can store their internal per-policy information in
> > policy->driver_data, lets use it.
> > 
> > we have benefits after this replacing.
> > 1) memory saving.
> > 2) policy is shared by several cpus, per_cpu seems not correct. using
> > *driver_data* is more reasonable.
> > 3) fix a memory leak in acpi_cpufreq_cpu_exit. as policy->cpu might
> > change during cpu hotplug. So sometimes we cant't free *data*, use
> > *driver_data* to fix it.
> > 4) fix a zero return value of get_cur_freq_on_cpu. Only per_cpu of
> > policy->cpu is set to *data*, if we try to get cpufreq on other cpus, we
> > get zero instead of correct values. Use *driver_data* to fix it.
> > 
> > Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com>
> > ---
> > Changes from V1:
> > 	codes style fix, comments update
> > 	move cpufreq_cpu_put(policy) after we get *driver_data*
> > ---
> >  drivers/cpufreq/acpi-cpufreq.c | 40 ++++++++++++++++++++++------------------
> >  1 file changed, 22 insertions(+), 18 deletions(-)
> 
> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>

OK

Does it fix any recent regressions or is it just an old bug?

Rafael

Re: [PATCH V2] acpi-cpufreq: replace per_cpu with driver_data of policy

[Pan Xinhui]

hi, Rafael
	thanks for your kind reply. :)

On 2015年07月09日 08:20, Rafael J. Wysocki wrote:
> On Tuesday, July 07, 2015 08:04:43 PM Viresh Kumar wrote:
>> On 07-07-15, 20:43, Pan Xinhui wrote:
>>>
>>> Drivers can store their internal per-policy information in
>>> policy->driver_data, lets use it.
>>>
>>> we have benefits after this replacing.
>>> 1) memory saving.
>>> 2) policy is shared by several cpus, per_cpu seems not correct. using
>>> *driver_data* is more reasonable.
>>> 3) fix a memory leak in acpi_cpufreq_cpu_exit. as policy->cpu might
>>> change during cpu hotplug. So sometimes we cant't free *data*, use
>>> *driver_data* to fix it.
>>> 4) fix a zero return value of get_cur_freq_on_cpu. Only per_cpu of
>>> policy->cpu is set to *data*, if we try to get cpufreq on other cpus, we
>>> get zero instead of correct values. Use *driver_data* to fix it.
>>>
>>> Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com>
>>> ---
>>> Changes from V1:
>>> 	codes style fix, comments update
>>> 	move cpufreq_cpu_put(policy) after we get *driver_data*
>>> ---
>>>  drivers/cpufreq/acpi-cpufreq.c | 40 ++++++++++++++++++++++------------------
>>>  1 file changed, 22 insertions(+), 18 deletions(-)
>>
>> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
> 
> OK
> 
> Does it fix any recent regressions or is it just an old bug?
> 

This patch achieve old bug fix and codes improvements. In past days, policy has no field *driver_data*, So
acpi-cpufreq driver has to use per_cpu to store some extra information. But it did not take good care of every scenarios.
Now cpufreq core makes awesome effort to store more per-policy information in policy. We can make use of this feature. So I
cook this patch. :)

I am preparing two patches for other two issues in acpi-cpufreq driver based on this patch.
I will fix them step by step. :)

thanks
xinhui

> Rafael
> 

Re: [PATCH V2] acpi-cpufreq: replace per_cpu with driver_data of policy

[Rafael J. Wysocki]

On Thursday, July 09, 2015 09:28:30 AM Pan Xinhui wrote:
> hi, Rafael
> 	thanks for your kind reply. :)
> 
> On 2015年07月09日 08:20, Rafael J. Wysocki wrote:
> > On Tuesday, July 07, 2015 08:04:43 PM Viresh Kumar wrote:
> >> On 07-07-15, 20:43, Pan Xinhui wrote:
> >>>
> >>> Drivers can store their internal per-policy information in
> >>> policy->driver_data, lets use it.
> >>>
> >>> we have benefits after this replacing.
> >>> 1) memory saving.
> >>> 2) policy is shared by several cpus, per_cpu seems not correct. using
> >>> *driver_data* is more reasonable.
> >>> 3) fix a memory leak in acpi_cpufreq_cpu_exit. as policy->cpu might
> >>> change during cpu hotplug. So sometimes we cant't free *data*, use
> >>> *driver_data* to fix it.
> >>> 4) fix a zero return value of get_cur_freq_on_cpu. Only per_cpu of
> >>> policy->cpu is set to *data*, if we try to get cpufreq on other cpus, we
> >>> get zero instead of correct values. Use *driver_data* to fix it.
> >>>
> >>> Signed-off-by: Pan Xinhui <xinhuix.pan@intel.com>
> >>> ---
> >>> Changes from V1:
> >>> 	codes style fix, comments update
> >>> 	move cpufreq_cpu_put(policy) after we get *driver_data*
> >>> ---
> >>>  drivers/cpufreq/acpi-cpufreq.c | 40 ++++++++++++++++++++++------------------
> >>>  1 file changed, 22 insertions(+), 18 deletions(-)
> >>
> >> Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
> > 
> > OK
> > 
> > Does it fix any recent regressions or is it just an old bug?
> > 
> 
> This patch achieve old bug fix and codes improvements. In past days, policy has no field *driver_data*, So
> acpi-cpufreq driver has to use per_cpu to store some extra information. But it did not take good care of every scenarios.
> Now cpufreq core makes awesome effort to store more per-policy information in policy. We can make use of this feature. So I
> cook this patch. :)

OK, patch applied, thanks!

> I am preparing two patches for other two issues in acpi-cpufreq driver based on this patch.
> I will fix them step by step. :)

Thanks for doing that!

Rafael