linux-kernel - Re: [PATCH v2 01/18] arm64: topology: Use __free(put_cpufreq

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Message-ID: <70f4c2ce-1dbd-4596-af78-bca1cdbbb581@arm.com>
Date: Wed, 27 Aug 2025 09:30:13 +0100
From: Ben Horgan <ben.horgan@....com>
To: Zihuan Zhang <zhangzihuan@...inos.cn>,
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Subject: Re: [PATCH v2 01/18] arm64: topology: Use __free(put_cpufreq_policy)
 for policy reference

Hi Zihuan,

On 8/27/25 03:31, Zihuan Zhang wrote:
> Replace the manual cpufreq_cpu_put() with __free(put_cpufreq_policy)
> annotation for policy references. This reduces the risk of reference
> counting mistakes and aligns the code with the latest kernel style.
> 
> No functional change intended.
> 
> Signed-off-by: Zihuan Zhang <zhangzihuan@...inos.cn>
> ---
>  arch/arm64/kernel/topology.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
> 
> diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c
> index 5d07ee85bdae..e3cb6d54f35b 100644
> --- a/arch/arm64/kernel/topology.c
> +++ b/arch/arm64/kernel/topology.c
> @@ -307,17 +307,16 @@ int arch_freq_get_on_cpu(int cpu)
>  		 */
>  		if (!housekeeping_cpu(cpu, HK_TYPE_TICK) ||
>  		    time_is_before_jiffies(last_update + msecs_to_jiffies(AMU_SAMPLE_EXP_MS))) {
> -			struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
> +			struct cpufreq_policy *policy __free(put_cpufreq_policy);
Based on the guidance, in include/linux/cleanup.h, I would expect the
assignment to be done on this line.

"...the recommendation is to always define and assign variables in one
 * statement and not group variable definitions at the top of the
 * function when __free() is used."
>  			int ref_cpu;
>  
> +			policy = cpufreq_cpu_get(cpu);
>  			if (!policy)
>  				return -EINVAL;
>  
>  			if (!cpumask_intersects(policy->related_cpus,
> -						housekeeping_cpumask(HK_TYPE_TICK))) {
> -				cpufreq_cpu_put(policy);
> +						housekeeping_cpumask(HK_TYPE_TICK)))
>  				return -EOPNOTSUPP;
> -			}
>  
>  			for_each_cpu_wrap(ref_cpu, policy->cpus, cpu + 1) {
>  				if (ref_cpu == start_cpu) {
> @@ -329,8 +328,6 @@ int arch_freq_get_on_cpu(int cpu)
>  					break;
>  			}
>  
> -			cpufreq_cpu_put(policy);
> -
>  			if (ref_cpu >= nr_cpu_ids)
>  				/* No alternative to pull info from */
>  				return -EAGAIN;

Thanks,

Ben