2024-02-27 09:16:39

by Shivnandan Kumar

Subject: [PATCH v2] 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.

Cc: <[email protected]>
Fixes: 1f39fa0dccff ("cpufreq: Introducing CPUFREQ_RELATION_E")
Signed-off-by: Shivnandan Kumar <[email protected]>
--

Changes in v2:
-rename function name from cpufreq_table_index_is_in_limits to cpufreq_is_in_limits
-remove redundant outer parenthesis in return statement
-Make comment single line

--
---
include/linux/cpufreq.h | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
index afda5f24d3dd..7741244dee6e 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_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 +1067,8 @@ 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_is_in_limits(policy, idx) && efficiencies) {
efficiencies = false;
goto retry;
}
--
2.25.1

2024-02-29 19:24:05

by Rafael J. Wysocki

Subject: Re: [PATCH v2] cpufreq: Limit resolving a frequency to policy min/max

On Tue, Feb 27, 2024 at 10:15 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.
>
> Cc: <[email protected]>
> Fixes: 1f39fa0dccff ("cpufreq: Introducing CPUFREQ_RELATION_E")
> Signed-off-by: Shivnandan Kumar <[email protected]>
> --
>
> Changes in v2:
> -rename function name from cpufreq_table_index_is_in_limits to cpufreq_is_in_limits
> -remove redundant outer parenthesis in return statement
> -Make comment single line
>
> --
> ---
> include/linux/cpufreq.h | 16 +++++++++++++++-
> 1 file changed, 15 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/cpufreq.h b/include/linux/cpufreq.h
> index afda5f24d3dd..7741244dee6e 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_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 +1067,8 @@ 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_is_in_limits(policy, idx) && efficiencies) {
> efficiencies = false;
> goto retry;
> }
> --

Applied (with a whitespace adjustment and changelog edits) as 6.9
material, thanks!