Replace the manual cpufreq_cpu_put() with __free(put_cpufreq_policy)
annotation for policy references. This reduces the risk of reference
counting mistakes and aligns the code with the latest kernel style.
No functional change intended.
Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
---
drivers/powercap/dtpm_cpu.c | 30 +++++++++++-------------------
1 file changed, 11 insertions(+), 19 deletions(-)
diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
index 99390ec1481f..f76594185fa2 100644
--- a/drivers/powercap/dtpm_cpu.c
+++ b/drivers/powercap/dtpm_cpu.c
@@ -144,19 +144,17 @@ static int update_pd_power_uw(struct dtpm *dtpm)
static void pd_release(struct dtpm *dtpm)
{
struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
- struct cpufreq_policy *policy;
if (freq_qos_request_active(&dtpm_cpu->qos_req))
freq_qos_remove_request(&dtpm_cpu->qos_req);
- policy = cpufreq_cpu_get(dtpm_cpu->cpu);
- if (policy) {
+ struct cpufreq_policy *policy __free(put_cpufreq_policy) =
+ cpufreq_cpu_get(dtpm_cpu->cpu);
+
+ if (policy)
for_each_cpu(dtpm_cpu->cpu, policy->related_cpus)
per_cpu(dtpm_per_cpu, dtpm_cpu->cpu) = NULL;
- cpufreq_cpu_put(policy);
- }
-
kfree(dtpm_cpu);
}
@@ -192,7 +190,6 @@ static int cpuhp_dtpm_cpu_online(unsigned int cpu)
static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
{
struct dtpm_cpu *dtpm_cpu;
- struct cpufreq_policy *policy;
struct em_perf_state *table;
struct em_perf_domain *pd;
char name[CPUFREQ_NAME_LEN];
@@ -202,21 +199,19 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
if (dtpm_cpu)
return 0;
- policy = cpufreq_cpu_get(cpu);
+ struct cpufreq_policy *policy __free(put_cpufreq_policy) =
+ cpufreq_cpu_get(cpu);
+
if (!policy)
return 0;
pd = em_cpu_get(cpu);
- if (!pd || em_is_artificial(pd)) {
- ret = -EINVAL;
- goto release_policy;
- }
+ if (!pd || em_is_artificial(pd))
+ return -EINVAL;
dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
- if (!dtpm_cpu) {
- ret = -ENOMEM;
- goto release_policy;
- }
+ if (!dtpm_cpu)
+ return -ENOMEM;
dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
dtpm_cpu->cpu = cpu;
@@ -239,7 +234,6 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
if (ret < 0)
goto out_dtpm_unregister;
- cpufreq_cpu_put(policy);
return 0;
out_dtpm_unregister:
@@ -251,8 +245,6 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
per_cpu(dtpm_per_cpu, cpu) = NULL;
kfree(dtpm_cpu);
-release_policy:
- cpufreq_cpu_put(policy);
return ret;
}
--
2.25.1On Wed, Sep 3, 2025 at 3:18 PM Zihuan Zhang <zhangzihuan@kylinos.cn> wrote:
>
> Replace the manual cpufreq_cpu_put() with __free(put_cpufreq_policy)
> annotation for policy references. This reduces the risk of reference
> counting mistakes and aligns the code with the latest kernel style.
>
> No functional change intended.
>
> Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
> ---
> drivers/powercap/dtpm_cpu.c | 30 +++++++++++-------------------
> 1 file changed, 11 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
> index 99390ec1481f..f76594185fa2 100644
> --- a/drivers/powercap/dtpm_cpu.c
> +++ b/drivers/powercap/dtpm_cpu.c
> @@ -144,19 +144,17 @@ static int update_pd_power_uw(struct dtpm *dtpm)
> static void pd_release(struct dtpm *dtpm)
> {
> struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
> - struct cpufreq_policy *policy;
>
> if (freq_qos_request_active(&dtpm_cpu->qos_req))
> freq_qos_remove_request(&dtpm_cpu->qos_req);
>
> - policy = cpufreq_cpu_get(dtpm_cpu->cpu);
> - if (policy) {
> + struct cpufreq_policy *policy __free(put_cpufreq_policy) =
> + cpufreq_cpu_get(dtpm_cpu->cpu);
> +
> + if (policy)
> for_each_cpu(dtpm_cpu->cpu, policy->related_cpus)
> per_cpu(dtpm_per_cpu, dtpm_cpu->cpu) = NULL;
>
> - cpufreq_cpu_put(policy);
> - }
> -
> kfree(dtpm_cpu);
> }
>
> @@ -192,7 +190,6 @@ static int cpuhp_dtpm_cpu_online(unsigned int cpu)
> static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
> {
> struct dtpm_cpu *dtpm_cpu;
> - struct cpufreq_policy *policy;
> struct em_perf_state *table;
> struct em_perf_domain *pd;
> char name[CPUFREQ_NAME_LEN];
> @@ -202,21 +199,19 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
> if (dtpm_cpu)
> return 0;
>
> - policy = cpufreq_cpu_get(cpu);
> + struct cpufreq_policy *policy __free(put_cpufreq_policy) =
> + cpufreq_cpu_get(cpu);
> +
> if (!policy)
> return 0;
>
> pd = em_cpu_get(cpu);
> - if (!pd || em_is_artificial(pd)) {
> - ret = -EINVAL;
> - goto release_policy;
> - }
> + if (!pd || em_is_artificial(pd))
> + return -EINVAL;
>
> dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
> - if (!dtpm_cpu) {
> - ret = -ENOMEM;
> - goto release_policy;
> - }
> + if (!dtpm_cpu)
> + return -ENOMEM;
>
> dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
> dtpm_cpu->cpu = cpu;
> @@ -239,7 +234,6 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
> if (ret < 0)
> goto out_dtpm_unregister;
So this change kind of goes against another recommendation given in cleanup.h:
* Lastly, given that the benefit of cleanup helpers is removal of
* "goto", and that the "goto" statement can jump between scopes, the
* expectation is that usage of "goto" and cleanup helpers is never
* mixed in the same function. I.e. for a given routine, convert all
* resources that need a "goto" cleanup to scope-based cleanup, or
* convert none of them.
>
> - cpufreq_cpu_put(policy);
> return 0;
>
> out_dtpm_unregister:
> @@ -251,8 +245,6 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
> per_cpu(dtpm_per_cpu, cpu) = NULL;
> kfree(dtpm_cpu);
>
> -release_policy:
> - cpufreq_cpu_put(policy);
> return ret;
> }
>
> --
在 2025/9/3 21:45, Rafael J. Wysocki 写道:
> On Wed, Sep 3, 2025 at 3:18 PM Zihuan Zhang <zhangzihuan@kylinos.cn> wrote:
>> Replace the manual cpufreq_cpu_put() with __free(put_cpufreq_policy)
>> annotation for policy references. This reduces the risk of reference
>> counting mistakes and aligns the code with the latest kernel style.
>>
>> No functional change intended.
>>
>> Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
>> ---
>> drivers/powercap/dtpm_cpu.c | 30 +++++++++++-------------------
>> 1 file changed, 11 insertions(+), 19 deletions(-)
>>
>> diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
>> index 99390ec1481f..f76594185fa2 100644
>> --- a/drivers/powercap/dtpm_cpu.c
>> +++ b/drivers/powercap/dtpm_cpu.c
>> @@ -144,19 +144,17 @@ static int update_pd_power_uw(struct dtpm *dtpm)
>> static void pd_release(struct dtpm *dtpm)
>> {
>> struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
>> - struct cpufreq_policy *policy;
>>
>> if (freq_qos_request_active(&dtpm_cpu->qos_req))
>> freq_qos_remove_request(&dtpm_cpu->qos_req);
>>
>> - policy = cpufreq_cpu_get(dtpm_cpu->cpu);
>> - if (policy) {
>> + struct cpufreq_policy *policy __free(put_cpufreq_policy) =
>> + cpufreq_cpu_get(dtpm_cpu->cpu);
>> +
>> + if (policy)
>> for_each_cpu(dtpm_cpu->cpu, policy->related_cpus)
>> per_cpu(dtpm_per_cpu, dtpm_cpu->cpu) = NULL;
>>
>> - cpufreq_cpu_put(policy);
>> - }
>> -
>> kfree(dtpm_cpu);
>> }
>>
>> @@ -192,7 +190,6 @@ static int cpuhp_dtpm_cpu_online(unsigned int cpu)
>> static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
>> {
>> struct dtpm_cpu *dtpm_cpu;
>> - struct cpufreq_policy *policy;
>> struct em_perf_state *table;
>> struct em_perf_domain *pd;
>> char name[CPUFREQ_NAME_LEN];
>> @@ -202,21 +199,19 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
>> if (dtpm_cpu)
>> return 0;
>>
>> - policy = cpufreq_cpu_get(cpu);
>> + struct cpufreq_policy *policy __free(put_cpufreq_policy) =
>> + cpufreq_cpu_get(cpu);
>> +
>> if (!policy)
>> return 0;
>>
>> pd = em_cpu_get(cpu);
>> - if (!pd || em_is_artificial(pd)) {
>> - ret = -EINVAL;
>> - goto release_policy;
>> - }
>> + if (!pd || em_is_artificial(pd))
>> + return -EINVAL;
>>
>> dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
>> - if (!dtpm_cpu) {
>> - ret = -ENOMEM;
>> - goto release_policy;
>> - }
>> + if (!dtpm_cpu)
>> + return -ENOMEM;
>>
>> dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
>> dtpm_cpu->cpu = cpu;
>> @@ -239,7 +234,6 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
>> if (ret < 0)
>> goto out_dtpm_unregister;
> So this change kind of goes against another recommendation given in cleanup.h:
>
> * Lastly, given that the benefit of cleanup helpers is removal of
> * "goto", and that the "goto" statement can jump between scopes, the
> * expectation is that usage of "goto" and cleanup helpers is never
> * mixed in the same function. I.e. for a given routine, convert all
> * resources that need a "goto" cleanup to scope-based cleanup, or
> * convert none of them.
Should I replace all the memory allocation cleanups here with `__free`?
That would allow us to drop all the `goto`s, but since this function has
quite a few of them, I’m concerned it might introduce new issues. What’s
your recommendation?
Thanks!
>> - cpufreq_cpu_put(policy);
>> return 0;
>>
>> out_dtpm_unregister:
>> @@ -251,8 +245,6 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
>> per_cpu(dtpm_per_cpu, cpu) = NULL;
>> kfree(dtpm_cpu);
>>
>> -release_policy:
>> - cpufreq_cpu_put(policy);
>> return ret;
>> }
>>
>> --
On Thu, Sep 4, 2025 at 12:38 PM Zihuan Zhang <zhangzihuan@kylinos.cn> wrote:
>
>
> 在 2025/9/3 21:45, Rafael J. Wysocki 写道:
> > On Wed, Sep 3, 2025 at 3:18 PM Zihuan Zhang <zhangzihuan@kylinos.cn> wrote:
> >> Replace the manual cpufreq_cpu_put() with __free(put_cpufreq_policy)
> >> annotation for policy references. This reduces the risk of reference
> >> counting mistakes and aligns the code with the latest kernel style.
> >>
> >> No functional change intended.
> >>
> >> Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
> >> ---
> >> drivers/powercap/dtpm_cpu.c | 30 +++++++++++-------------------
> >> 1 file changed, 11 insertions(+), 19 deletions(-)
> >>
> >> diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
> >> index 99390ec1481f..f76594185fa2 100644
> >> --- a/drivers/powercap/dtpm_cpu.c
> >> +++ b/drivers/powercap/dtpm_cpu.c
> >> @@ -144,19 +144,17 @@ static int update_pd_power_uw(struct dtpm *dtpm)
> >> static void pd_release(struct dtpm *dtpm)
> >> {
> >> struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
> >> - struct cpufreq_policy *policy;
> >>
> >> if (freq_qos_request_active(&dtpm_cpu->qos_req))
> >> freq_qos_remove_request(&dtpm_cpu->qos_req);
> >>
> >> - policy = cpufreq_cpu_get(dtpm_cpu->cpu);
> >> - if (policy) {
> >> + struct cpufreq_policy *policy __free(put_cpufreq_policy) =
> >> + cpufreq_cpu_get(dtpm_cpu->cpu);
> >> +
> >> + if (policy)
> >> for_each_cpu(dtpm_cpu->cpu, policy->related_cpus)
> >> per_cpu(dtpm_per_cpu, dtpm_cpu->cpu) = NULL;
> >>
> >> - cpufreq_cpu_put(policy);
> >> - }
> >> -
> >> kfree(dtpm_cpu);
> >> }
> >>
> >> @@ -192,7 +190,6 @@ static int cpuhp_dtpm_cpu_online(unsigned int cpu)
> >> static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
> >> {
> >> struct dtpm_cpu *dtpm_cpu;
> >> - struct cpufreq_policy *policy;
> >> struct em_perf_state *table;
> >> struct em_perf_domain *pd;
> >> char name[CPUFREQ_NAME_LEN];
> >> @@ -202,21 +199,19 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
> >> if (dtpm_cpu)
> >> return 0;
> >>
> >> - policy = cpufreq_cpu_get(cpu);
> >> + struct cpufreq_policy *policy __free(put_cpufreq_policy) =
> >> + cpufreq_cpu_get(cpu);
> >> +
> >> if (!policy)
> >> return 0;
> >>
> >> pd = em_cpu_get(cpu);
> >> - if (!pd || em_is_artificial(pd)) {
> >> - ret = -EINVAL;
> >> - goto release_policy;
> >> - }
> >> + if (!pd || em_is_artificial(pd))
> >> + return -EINVAL;
> >>
> >> dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
> >> - if (!dtpm_cpu) {
> >> - ret = -ENOMEM;
> >> - goto release_policy;
> >> - }
> >> + if (!dtpm_cpu)
> >> + return -ENOMEM;
> >>
> >> dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
> >> dtpm_cpu->cpu = cpu;
> >> @@ -239,7 +234,6 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
> >> if (ret < 0)
> >> goto out_dtpm_unregister;
> > So this change kind of goes against another recommendation given in cleanup.h:
> >
> > * Lastly, given that the benefit of cleanup helpers is removal of
> > * "goto", and that the "goto" statement can jump between scopes, the
> > * expectation is that usage of "goto" and cleanup helpers is never
> > * mixed in the same function. I.e. for a given routine, convert all
> > * resources that need a "goto" cleanup to scope-based cleanup, or
> > * convert none of them.
>
>
> Should I replace all the memory allocation cleanups here with `__free`?
> That would allow us to drop all the `goto`s, but since this function has
> quite a few of them, I’m concerned it might introduce new issues. What’s
> your recommendation?
Frankly, don't use __free() in this code at all, at least for the time being.
There is a problem with dropping the reference to policy at the end of
__dtpm_cpu_setup() because that policy may be subsequently indirectly
used in set_pd_power_limit() which calls
freq_qos_update_request(&dtpm_cpu->qos_req, freq) and
dtpm_cpu->qos_req->qos is policy->constraints, so using it will cause
policy->constraints to be dereferenced in freq_qos_apply() which will
crash and burn if the policy goes away in the meantime. So AFAICS
__dtpm_cpu_setup() shouldn't call cpufreq_cpu_put() at all and the
policy should be released in pd_release() without acquiring a new
reference to it.
You may as well try to fix this if you have free cycles.
在 2025/9/4 21:17, Rafael J. Wysocki 写道:
> On Thu, Sep 4, 2025 at 12:38 PM Zihuan Zhang <zhangzihuan@kylinos.cn> wrote:
>>
>> 在 2025/9/3 21:45, Rafael J. Wysocki 写道:
>>> On Wed, Sep 3, 2025 at 3:18 PM Zihuan Zhang <zhangzihuan@kylinos.cn> wrote:
>>>> Replace the manual cpufreq_cpu_put() with __free(put_cpufreq_policy)
>>>> annotation for policy references. This reduces the risk of reference
>>>> counting mistakes and aligns the code with the latest kernel style.
>>>>
>>>> No functional change intended.
>>>>
>>>> Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
>>>> ---
>>>> drivers/powercap/dtpm_cpu.c | 30 +++++++++++-------------------
>>>> 1 file changed, 11 insertions(+), 19 deletions(-)
>>>>
>>>> diff --git a/drivers/powercap/dtpm_cpu.c b/drivers/powercap/dtpm_cpu.c
>>>> index 99390ec1481f..f76594185fa2 100644
>>>> --- a/drivers/powercap/dtpm_cpu.c
>>>> +++ b/drivers/powercap/dtpm_cpu.c
>>>> @@ -144,19 +144,17 @@ static int update_pd_power_uw(struct dtpm *dtpm)
>>>> static void pd_release(struct dtpm *dtpm)
>>>> {
>>>> struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
>>>> - struct cpufreq_policy *policy;
>>>>
>>>> if (freq_qos_request_active(&dtpm_cpu->qos_req))
>>>> freq_qos_remove_request(&dtpm_cpu->qos_req);
>>>>
>>>> - policy = cpufreq_cpu_get(dtpm_cpu->cpu);
>>>> - if (policy) {
>>>> + struct cpufreq_policy *policy __free(put_cpufreq_policy) =
>>>> + cpufreq_cpu_get(dtpm_cpu->cpu);
>>>> +
>>>> + if (policy)
>>>> for_each_cpu(dtpm_cpu->cpu, policy->related_cpus)
>>>> per_cpu(dtpm_per_cpu, dtpm_cpu->cpu) = NULL;
>>>>
>>>> - cpufreq_cpu_put(policy);
>>>> - }
>>>> -
>>>> kfree(dtpm_cpu);
>>>> }
>>>>
>>>> @@ -192,7 +190,6 @@ static int cpuhp_dtpm_cpu_online(unsigned int cpu)
>>>> static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
>>>> {
>>>> struct dtpm_cpu *dtpm_cpu;
>>>> - struct cpufreq_policy *policy;
>>>> struct em_perf_state *table;
>>>> struct em_perf_domain *pd;
>>>> char name[CPUFREQ_NAME_LEN];
>>>> @@ -202,21 +199,19 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
>>>> if (dtpm_cpu)
>>>> return 0;
>>>>
>>>> - policy = cpufreq_cpu_get(cpu);
>>>> + struct cpufreq_policy *policy __free(put_cpufreq_policy) =
>>>> + cpufreq_cpu_get(cpu);
>>>> +
>>>> if (!policy)
>>>> return 0;
>>>>
>>>> pd = em_cpu_get(cpu);
>>>> - if (!pd || em_is_artificial(pd)) {
>>>> - ret = -EINVAL;
>>>> - goto release_policy;
>>>> - }
>>>> + if (!pd || em_is_artificial(pd))
>>>> + return -EINVAL;
>>>>
>>>> dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
>>>> - if (!dtpm_cpu) {
>>>> - ret = -ENOMEM;
>>>> - goto release_policy;
>>>> - }
>>>> + if (!dtpm_cpu)
>>>> + return -ENOMEM;
>>>>
>>>> dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
>>>> dtpm_cpu->cpu = cpu;
>>>> @@ -239,7 +234,6 @@ static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
>>>> if (ret < 0)
>>>> goto out_dtpm_unregister;
>>> So this change kind of goes against another recommendation given in cleanup.h:
>>>
>>> * Lastly, given that the benefit of cleanup helpers is removal of
>>> * "goto", and that the "goto" statement can jump between scopes, the
>>> * expectation is that usage of "goto" and cleanup helpers is never
>>> * mixed in the same function. I.e. for a given routine, convert all
>>> * resources that need a "goto" cleanup to scope-based cleanup, or
>>> * convert none of them.
>>
>> Should I replace all the memory allocation cleanups here with `__free`?
>> That would allow us to drop all the `goto`s, but since this function has
>> quite a few of them, I’m concerned it might introduce new issues. What’s
>> your recommendation?
> Frankly, don't use __free() in this code at all, at least for the time being.
>
> There is a problem with dropping the reference to policy at the end of
> __dtpm_cpu_setup() because that policy may be subsequently indirectly
> used in set_pd_power_limit() which calls
> freq_qos_update_request(&dtpm_cpu->qos_req, freq) and
> dtpm_cpu->qos_req->qos is policy->constraints, so using it will cause
> policy->constraints to be dereferenced in freq_qos_apply() which will
> crash and burn if the policy goes away in the meantime. So AFAICS
> __dtpm_cpu_setup() shouldn't call cpufreq_cpu_put() at all and the
> policy should be released in pd_release() without acquiring a new
> reference to it.
>
Thanks a lot for the detailed explanation!
On 04/09/2025 12:37, Zihuan Zhang wrote: >> * Lastly, given that the benefit of cleanup helpers is removal of >> * "goto", and that the "goto" statement can jump between scopes, the >> * expectation is that usage of "goto" and cleanup helpers is never >> * mixed in the same function. I.e. for a given routine, convert all >> * resources that need a "goto" cleanup to scope-based cleanup, or >> * convert none of them. > > > Should I replace all the memory allocation cleanups here with `__free`? > That would allow us to drop all the `goto`s, but since this function has > quite a few of them, I’m concerned it might introduce new issues. What’s > your recommendation? If you keep asking this, I have doubts you really know how to use cleanup.h. Don't blindly convert code to cleanup.h. It's very odd syntax and it is not even welcomed everywhere. Best regards, Krzysztof
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