linux-kernel - Re: [PATCH -next v4 1/3] cpuset: decouple tmpmasks and cpumasks freeing in cgroup

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Message-ID: <54e1466c-8db7-4fd1-a60f-5590015afaf2@redhat.com>
Date: Sun, 24 Aug 2025 13:07:00 -0400
From: Waiman Long <llong@...hat.com>
To: Chen Ridong <chenridong@...weicloud.com>, tj@...nel.org,
 hannes@...xchg.org, mkoutny@...e.com
Cc: cgroups@...r.kernel.org, linux-kernel@...r.kernel.org,
 lujialin4@...wei.com, chenridong@...wei.com
Subject: Re: [PATCH -next v4 1/3] cpuset: decouple tmpmasks and cpumasks
 freeing in cgroup

On 8/18/25 2:41 AM, Chen Ridong wrote:
> From: Chen Ridong <chenridong@...wei.com>
>
> Currently, free_cpumasks() can free both tmpmasks and cpumasks of a cpuset
> (cs). However, these two operations are not logically coupled. To improve
> code clarity:
> 1. Move cpumask freeing to free_cpuset()
> 2. Rename free_cpumasks() to free_tmpmasks()
>
> This change enforces the single responsibility principle.
>
> Signed-off-by: Chen Ridong <chenridong@...wei.com>
> ---
>   kernel/cgroup/cpuset.c | 32 +++++++++++++-------------------
>   1 file changed, 13 insertions(+), 19 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 3466ebbf1016..aebda14cc67f 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -459,23 +459,14 @@ static inline int alloc_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
>   }
>   
>   /**
> - * free_cpumasks - free cpumasks in a tmpmasks structure
> - * @cs:  the cpuset that have cpumasks to be free.
> + * free_tmpmasks - free cpumasks in a tmpmasks structure
>    * @tmp: the tmpmasks structure pointer
>    */
> -static inline void free_cpumasks(struct cpuset *cs, struct tmpmasks *tmp)
> +static inline void free_tmpmasks(struct tmpmasks *tmp)
>   {
> -	if (cs) {
> -		free_cpumask_var(cs->cpus_allowed);
> -		free_cpumask_var(cs->effective_cpus);
> -		free_cpumask_var(cs->effective_xcpus);
> -		free_cpumask_var(cs->exclusive_cpus);
> -	}
> -	if (tmp) {
> -		free_cpumask_var(tmp->new_cpus);
> -		free_cpumask_var(tmp->addmask);
> -		free_cpumask_var(tmp->delmask);
> -	}
> +	free_cpumask_var(tmp->new_cpus);
> +	free_cpumask_var(tmp->addmask);
> +	free_cpumask_var(tmp->delmask);
>   }
>   
>   /**
> @@ -508,7 +499,10 @@ static struct cpuset *alloc_trial_cpuset(struct cpuset *cs)
>    */
>   static inline void free_cpuset(struct cpuset *cs)
>   {
> -	free_cpumasks(cs, NULL);
> +	free_cpumask_var(cs->cpus_allowed);
> +	free_cpumask_var(cs->effective_cpus);
> +	free_cpumask_var(cs->effective_xcpus);
> +	free_cpumask_var(cs->exclusive_cpus);
>   	kfree(cs);
>   }
>   
> @@ -2427,7 +2421,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
>   	if (cs->partition_root_state)
>   		update_partition_sd_lb(cs, old_prs);
>   out_free:
> -	free_cpumasks(NULL, &tmp);
> +	free_tmpmasks(&tmp);
>   	return retval;
>   }
>   
> @@ -2530,7 +2524,7 @@ static int update_exclusive_cpumask(struct cpuset *cs, struct cpuset *trialcs,
>   	if (cs->partition_root_state)
>   		update_partition_sd_lb(cs, old_prs);
>   
> -	free_cpumasks(NULL, &tmp);
> +	free_tmpmasks(&tmp);
>   	return 0;
>   }
>   
> @@ -2983,7 +2977,7 @@ static int update_prstate(struct cpuset *cs, int new_prs)
>   	notify_partition_change(cs, old_prs);
>   	if (force_sd_rebuild)
>   		rebuild_sched_domains_locked();
> -	free_cpumasks(NULL, &tmpmask);
> +	free_tmpmasks(&tmpmask);
>   	return 0;
>   }
>   
> @@ -4006,7 +4000,7 @@ static void cpuset_handle_hotplug(void)
>   	if (force_sd_rebuild)
>   		rebuild_sched_domains_cpuslocked();
>   
> -	free_cpumasks(NULL, ptmp);
> +	free_tmpmasks(ptmp);
>   }
>   
>   void cpuset_update_active_cpus(void)
Reviewed-by: Waiman Long <longman@...hat.com>