Re: [RFC PATCH 1/2] thermal/cpufreq_cooling: remove unused cpu_idx in get_load()

[Lukasz Luba <lukasz.luba@arm.com>]

Hi Xuewen,

On 3/20/26 11:31, Xuewen Yan wrote:
> From: Di Shen <di.shen@unisoc.com>
> 
> The cpu_idx variable in the get_load function is now
> unused and can be safely removed.
> 
> No code logic is affected.
> 
> Signed-off-by: Di Shen <di.shen@unisoc.com>
> ---
>   drivers/thermal/cpufreq_cooling.c | 13 +++++--------
>   1 file changed, 5 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/thermal/cpufreq_cooling.c b/drivers/thermal/cpufreq_cooling.c
> index 32bf5ab44f4a..d030dbeb2973 100644
> --- a/drivers/thermal/cpufreq_cooling.c
> +++ b/drivers/thermal/cpufreq_cooling.c
> @@ -151,26 +151,23 @@ static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_cdev,
>    * get_load() - get load for a cpu
>    * @cpufreq_cdev: struct cpufreq_cooling_device for the cpu
>    * @cpu: cpu number
> - * @cpu_idx: index of the cpu in time_in_idle array
>    *
>    * Return: The average load of cpu @cpu in percentage since this
>    * function was last called.
>    */
>   #ifdef CONFIG_SMP
> -static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
> -		    int cpu_idx)
> +static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu)
>   {
>   	unsigned long util = sched_cpu_util(cpu);
>   
>   	return (util * 100) / arch_scale_cpu_capacity(cpu);
>   }
>   #else /* !CONFIG_SMP */
> -static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu,
> -		    int cpu_idx)
> +static u32 get_load(struct cpufreq_cooling_device *cpufreq_cdev, int cpu)
>   {
>   	u32 load;
>   	u64 now, now_idle, delta_time, delta_idle;
> -	struct time_in_idle *idle_time = &cpufreq_cdev->idle_time[cpu_idx];
> +	struct time_in_idle *idle_time = &cpufreq_cdev->idle_time[cpu];

This is a bug. We allocate 'num_cpus' size of array based on
number of CPU in the cpumask for a given cpufreq policy.
If there are 4 cpus in the CPU cluster but CPUs have ids:
CPU4-7 then accessing it with this change would explode.

Please re-design this patch set slightly and I will have a look
on the 2nd version (and particularly the part in current patch 2/2).

Regards,
Lukasz