2024-02-22 08:36:24

by Shivnandan Kumar

Subject: [PATCH] cpufreq: Limit resolving a frequency to policy min/max

Resolving a frequency to an efficient one should not transgress policy->max
(which can be set for thermal reason) and policy->min. Currently there is
possibility where scaling_cur_freq can exceed scaling_max_freq when
scaling_max_freq is inefficient frequency. Add additional check to ensure
that resolving a frequency will respect policy->min/max.

Fixes: 1f39fa0dccff ("cpufreq: Introducing CPUFREQ_RELATION_E")
Signed-off-by: Shivnandan Kumar <[email protected]>
---
include/linux/cpufreq.h | 18 +++++++++++++++++-
1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index afda5f24d3dd..42d98b576a36 100644
--- a/include/linux/cpufreq.h
+++ b/include/linux/cpufreq.h
@@ -1021,6 +1021,19 @@ static inline int cpufreq_table_find_index_c(struct cpufreq_policy *policy,
efficiencies);
}

+static inline bool cpufreq_table_index_is_in_limits(struct cpufreq_policy *policy,
+ int idx)
+{
+ unsigned int freq;
+
+ if (idx < 0)
+ return false;
+
+ freq = policy->freq_table[idx].frequency;
+
+ return (freq == clamp_val(freq, policy->min, policy->max));
+}
+
static inline int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
@@ -1054,7 +1067,10 @@ static inline int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
return 0;
}

- if (idx < 0 && efficiencies) {
+ /*
+ * Limit frequency index to honor policy->min/max
+ */
+ if (!cpufreq_table_index_is_in_limits(policy, idx) && efficiencies) {
efficiencies = false;
goto retry;
}
--
2.25.1

2024-02-22 19:26:41

by Rafael J. Wysocki

Subject: Re: [PATCH] cpufreq: Limit resolving a frequency to policy min/max

On Thu, Feb 22, 2024 at 9:35 AM Shivnandan Kumar
<[email protected]> wrote:
>
> Resolving a frequency to an efficient one should not transgress policy->max
> (which can be set for thermal reason) and policy->min. Currently there is
> possibility where scaling_cur_freq can exceed scaling_max_freq when
> scaling_max_freq is inefficient frequency. Add additional check to ensure
> that resolving a frequency will respect policy->min/max.
>
> Fixes: 1f39fa0dccff ("cpufreq: Introducing CPUFREQ_RELATION_E")
> Signed-off-by: Shivnandan Kumar <[email protected]>
> ---
> include/linux/cpufreq.h | 18 +++++++++++++++++-
> 1 file changed, 17 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index afda5f24d3dd..42d98b576a36 100644
> --- a/include/linux/cpufreq.h
> +++ b/include/linux/cpufreq.h
> @@ -1021,6 +1021,19 @@ static inline int cpufreq_table_find_index_c(struct cpufreq_policy *policy,
> efficiencies);
> }
>
> +static inline bool cpufreq_table_index_is_in_limits(struct cpufreq_policy *policy,
> + int idx)

This is not really about the index only, but about the frequency at
that index too, so I'd call the function differently.

> +{
> + unsigned int freq;
> +
> + if (idx < 0)
> + return false;
> +
> + freq = policy->freq_table[idx].frequency;
> +
> + return (freq == clamp_val(freq, policy->min, policy->max));

Redundant outer parens.

> +}
> +
> static inline int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
> unsigned int target_freq,
> unsigned int relation)
> @@ -1054,7 +1067,10 @@ static inline int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
> return 0;
> }
>
> - if (idx < 0 && efficiencies) {
> + /*
> + * Limit frequency index to honor policy->min/max
> + */

This comment need not be multi-line.

> + if (!cpufreq_table_index_is_in_limits(policy, idx) && efficiencies) {
> efficiencies = false;
> goto retry;
> }
> --

Thanks!

2024-02-24 15:23:54

by Shivnandan Kumar

Subject: Re: [PATCH] cpufreq: Limit resolving a frequency to policy min/max

Hi Rafael,

Thanks for reviewing the change.

On 2/23/2024 12:52 AM, Rafael J. Wysocki wrote:
> On Thu, Feb 22, 2024 at 9:35 AM Shivnandan Kumar
> <[email protected]> wrote:
>>
>> Resolving a frequency to an efficient one should not transgress policy->max
>> (which can be set for thermal reason) and policy->min. Currently there is
>> possibility where scaling_cur_freq can exceed scaling_max_freq when
>> scaling_max_freq is inefficient frequency. Add additional check to ensure
>> that resolving a frequency will respect policy->min/max.
>>
>> Fixes: 1f39fa0dccff ("cpufreq: Introducing CPUFREQ_RELATION_E")
>> Signed-off-by: Shivnandan Kumar <[email protected]>
>> ---
>> include/linux/cpufreq.h | 18 +++++++++++++++++-
>> 1 file changed, 17 insertions(+), 1 deletion(-)
>>
>> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
>> index afda5f24d3dd..42d98b576a36 100644
>> --- a/include/linux/cpufreq.h
>> +++ b/include/linux/cpufreq.h
>> @@ -1021,6 +1021,19 @@ static inline int cpufreq_table_find_index_c(struct cpufreq_policy *policy,
>> efficiencies);
>> }
>>
>> +static inline bool cpufreq_table_index_is_in_limits(struct cpufreq_policy *policy,
>> + int idx)
>
> This is not really about the index only, but about the frequency at
> that index too, so I'd call the function differently.
>

ACK

>> +{
>> + unsigned int freq;
>> +
>> + if (idx < 0)
>> + return false;
>> +
>> + freq = policy->freq_table[idx].frequency;
>> +
>> + return (freq == clamp_val(freq, policy->min, policy->max));
>
> Redundant outer parens.
>

ACK


>> +}
>> +
>> static inline int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
>> unsigned int target_freq,
>> unsigned int relation)
>> @@ -1054,7 +1067,10 @@ static inline int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
>> return 0;
>> }
>>
>> - if (idx < 0 && efficiencies) {
>> + /*
>> + * Limit frequency index to honor policy->min/max
>> + */
>
> This comment need not be multi-line.
>

ACK
I will make the changes in next patch set.

Thanks
Shivnandan

>> + if (!cpufreq_table_index_is_in_limits(policy, idx) && efficiencies) {
>> efficiencies = false;
>> goto retry;
>> }
>> --
>
> Thanks!