[PATCH v3 0/2] cpufreq: Cleanups and minor fixes

[PATCH v3 0/2] cpufreq: Cleanups and minor fixes

[Zihuan Zhang]

This series contains two small cpufreq cleanups:

  1) Use strlen() as the length argument for strncasecmp() in
     cpufreq_parse_policy(). This makes comparison more permissive
     (prefix match), which is consistent with the intention in our
     deployment and improves readability over using CPUFREQ_NAME_LEN.

  2) The second patch is new in this version. It simplifies the validation
     logic in cpufreq_register_driver().This makes the registration code 
     more straightforward without changing functionality.

Changes since v2:
    - Fix code suggested by Viresh Kumar

Changes since v1:
	- Dropped the second patch from v1, which was not needed.
	- Kept the first patch as-is (already Acked).
	- Added a new second patch to simplify driver registration checks

Zihuan Zhang (2):
  cpufreq: use strlen() for governor name comparison
  cpufreq: simplify setpolicy/target check in driver verification

 drivers/cpufreq/cpufreq.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

-- 
2.25.1

[PATCH v3 1/2] cpufreq: use strlen() for governor name comparison

[Zihuan Zhang]

Most kernel code using strncasecmp()/strncmp() passes strlen("xxx")
as the length argument. cpufreq_parse_policy() previously used
CPUFREQ_NAME_LEN (16), which is longer than the actual strings
("performance" is 11 chars, "powersave" is 9 chars).

This patch switches to strlen() for the comparison, making the
matching slightly more permissive (e.g., "powersavexxx" will now
also match "powersave"). While this is unlikely to cause functional
issues, it aligns cpufreq with common kernel style and makes the
behavior more intuitive.

Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
Acked-by: Viresh Kumar <viresh.kumar@linaro.org>
---
 drivers/cpufreq/cpufreq.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index fc7eace8b65b..a067b5447fe8 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -664,10 +664,10 @@ static struct cpufreq_governor *get_governor(const char *str_governor)
 
 static unsigned int cpufreq_parse_policy(char *str_governor)
 {
-	if (!strncasecmp(str_governor, "performance", CPUFREQ_NAME_LEN))
+	if (!strncasecmp(str_governor, "performance", strlen("performance")))
 		return CPUFREQ_POLICY_PERFORMANCE;
 
-	if (!strncasecmp(str_governor, "powersave", CPUFREQ_NAME_LEN))
+	if (!strncasecmp(str_governor, "powersave", strlen("powersave")))
 		return CPUFREQ_POLICY_POWERSAVE;
 
 	return CPUFREQ_POLICY_UNKNOWN;
-- 
2.25.1

[PATCH v3 2/2] cpufreq: simplify setpolicy/target check in driver verification

[Zihuan Zhang]

Cpufreq drivers are supposed to use either ->setpolicy or
->target/->target_index. This patch simplifies the existing check by
collapsing it into a single boolean expression:

    (!!driver->setpolicy == (driver->target_index || driver->target))

This is a readability/maintainability cleanup and keeps the semantics
unchanged.

No functional change intended.

Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
---
 drivers/cpufreq/cpufreq.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a067b5447fe8..633be16297d6 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2921,10 +2921,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 		return -EPROBE_DEFER;
 
 	if (!driver_data || !driver_data->verify || !driver_data->init ||
-	    !(driver_data->setpolicy || driver_data->target_index ||
-		    driver_data->target) ||
-	     (driver_data->setpolicy && (driver_data->target_index ||
-		    driver_data->target)) ||
+	     (!!driver_data->setpolicy == (driver_data->target_index || driver_data->target)) ||
 	     (!driver_data->get_intermediate != !driver_data->target_intermediate) ||
 	     (!driver_data->online != !driver_data->offline) ||
 		 (driver_data->adjust_perf && !driver_data->fast_switch))
-- 
2.25.1

Re: [PATCH v3 2/2] cpufreq: simplify setpolicy/target check in driver verification

[Viresh Kumar]

On 22-08-25, 15:04, Zihuan Zhang wrote:
> Cpufreq drivers are supposed to use either ->setpolicy or
> ->target/->target_index. This patch simplifies the existing check by
> collapsing it into a single boolean expression:
> 
>     (!!driver->setpolicy == (driver->target_index || driver->target))
> 
> This is a readability/maintainability cleanup and keeps the semantics
> unchanged.
> 
> No functional change intended.
> 
> Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
> ---
>  drivers/cpufreq/cpufreq.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index a067b5447fe8..633be16297d6 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2921,10 +2921,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
>  		return -EPROBE_DEFER;
>  
>  	if (!driver_data || !driver_data->verify || !driver_data->init ||
> -	    !(driver_data->setpolicy || driver_data->target_index ||
> -		    driver_data->target) ||
> -	     (driver_data->setpolicy && (driver_data->target_index ||
> -		    driver_data->target)) ||
> +	     (!!driver_data->setpolicy == (driver_data->target_index || driver_data->target)) ||
>  	     (!driver_data->get_intermediate != !driver_data->target_intermediate) ||
>  	     (!driver_data->online != !driver_data->offline) ||
>  		 (driver_data->adjust_perf && !driver_data->fast_switch))

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

-- 
viresh

Re: [PATCH v3 0/2] cpufreq: Cleanups and minor fixes

[Rafael J. Wysocki]

On Fri, Aug 22, 2025 at 9:04 AM Zihuan Zhang <zhangzihuan@kylinos.cn> wrote:
>
> This series contains two small cpufreq cleanups:
>
>   1) Use strlen() as the length argument for strncasecmp() in
>      cpufreq_parse_policy(). This makes comparison more permissive
>      (prefix match), which is consistent with the intention in our
>      deployment and improves readability over using CPUFREQ_NAME_LEN.
>
>   2) The second patch is new in this version. It simplifies the validation
>      logic in cpufreq_register_driver().This makes the registration code
>      more straightforward without changing functionality.
>
> Changes since v2:
>     - Fix code suggested by Viresh Kumar
>
> Changes since v1:
>         - Dropped the second patch from v1, which was not needed.
>         - Kept the first patch as-is (already Acked).
>         - Added a new second patch to simplify driver registration checks
>
> Zihuan Zhang (2):
>   cpufreq: use strlen() for governor name comparison
>   cpufreq: simplify setpolicy/target check in driver verification
>
>  drivers/cpufreq/cpufreq.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
>
> --

Both patches applied as 6.18 material, thanks!