Currently the driver verification code uses two separate conditions to
ensure that exactly one of setpolicy or target functions is provided:

    if (!has_setpolicy && !has_target)
        return -EINVAL;
    if (has_setpolicy && has_target)
        return -EINVAL;

This can be simplified into a single condition:

    if (has_setpolicy == has_target)
        return -EINVAL;

which makes the intent clearer and avoids duplicated logic.
No functional changes intended.

Signed-off-by: Zihuan Zhang <zhangzihuan@kylinos.cn>
---
 drivers/cpufreq/cpufreq.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
index a067b5447fe8..92633ff2c4f3 100644
--- a/drivers/cpufreq/cpufreq.c
+++ b/drivers/cpufreq/cpufreq.c
@@ -2908,6 +2908,8 @@ static int cpuhp_cpufreq_offline(unsigned int cpu)
 int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 {
 	unsigned long flags;
+	bool has_setpolicy = driver_data->setpolicy;
+	bool has_target = driver_data->target_index || driver_data->target;
 	int ret;
 
 	if (cpufreq_disabled())
@@ -2921,10 +2923,7 @@ 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)) ||
+	     (has_setpolicy == has_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

On 21-08-25, 17:00, Zihuan Zhang wrote:
> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
> index a067b5447fe8..92633ff2c4f3 100644
> --- a/drivers/cpufreq/cpufreq.c
> +++ b/drivers/cpufreq/cpufreq.c
> @@ -2908,6 +2908,8 @@ static int cpuhp_cpufreq_offline(unsigned int cpu)
>  int cpufreq_register_driver(struct cpufreq_driver *driver_data)
>  {
>  	unsigned long flags;

driver_data can be NULL here. It is checked at a later point.

> +	bool has_setpolicy = driver_data->setpolicy;

This is a pointer and ..

> +	bool has_target = driver_data->target_index || driver_data->target;

.. this is bool.

Their comparison will always fail. Did you actually try this with both
setpolicy and target() set for a cpufreq driver to check if it really
fails ?

What you need is:

	bool has_setpolicy = !!driver_data->setpolicy;

>  	int ret;
>  
>  	if (cpufreq_disabled())
> @@ -2921,10 +2923,7 @@ 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)) ||
> +	     (has_setpolicy == has_target) ||

I would rather do:

	(!!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

-- 
viresh

在 2025/8/21 17:17, Viresh Kumar 写道:
> On 21-08-25, 17:00, Zihuan Zhang wrote:
>> diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
>> index a067b5447fe8..92633ff2c4f3 100644
>> --- a/drivers/cpufreq/cpufreq.c
>> +++ b/drivers/cpufreq/cpufreq.c
>> @@ -2908,6 +2908,8 @@ static int cpuhp_cpufreq_offline(unsigned int cpu)
>>   int cpufreq_register_driver(struct cpufreq_driver *driver_data)
>>   {
>>   	unsigned long flags;
> driver_data can be NULL here. It is checked at a later point.
>
Thanks for your feedback. I did think about the case where driver_data 
is NULL, but I didn’t think it through properly at the time.

You are right — this clearly can cause issues.

>> +	bool has_setpolicy = driver_data->setpolicy;
> This is a pointer and ..
>
>> +	bool has_target = driver_data->target_index || driver_data->target;
> .. this is bool.
>
> Their comparison will always fail. Did you actually try this with both
> setpolicy and target() set for a cpufreq driver to check if it really
> fails ?
>
> What you need is:
>
> 	bool has_setpolicy = !!driver_data->setpolicy;
Sorry about that. I only tested the case where driver registration succeeds.

Do you have any suggestions on how to better test or handle the cases 
where driver registration could fail?
>>   	int ret;
>>   
>>   	if (cpufreq_disabled())
>> @@ -2921,10 +2923,7 @@ 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)) ||
>> +	     (has_setpolicy == has_target) ||
> I would rather do:
>
> 	(!!driver_data->setpolicy == (driver_data->target_index || driver_data->target))

The current version of the code is much better and safer.

Thanks for pointing this out.

I will carefully test all cases, including potential failure paths, and 
send a next version accordingly.

>>   	     (!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

On 21-08-25, 17:45, Zihuan Zhang wrote:
> Do you have any suggestions on how to better test or handle the cases where
> driver registration could fail?

That's what I suggested earlier.

> > I would rather do:
> > 
> > 	(!!driver_data->setpolicy == (driver_data->target_index || driver_data->target))
> 
> The current version of the code is much better and safer.

You can actually do this.. This first converts
`driver_data->setpolicy` to bool and then compares both of them, and
both can't be true or false.

-- 
viresh

在 2025/8/21 17:56, Viresh Kumar 写道:
> On 21-08-25, 17:45, Zihuan Zhang wrote:
>>> I would rather do:
>>>
>>> 	(!!driver_data->setpolicy == (driver_data->target_index || driver_data->target))
>> The current version of the code is much better and safer.
> You can actually do this.. This first converts
> `driver_data->setpolicy` to bool and then compares both of them, and
> both can't be true or false.

Thanks. I will.