linux-kernel - Re: [PATCH -next RFC -v2 11/11] cpuset: use partition_cpus

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Message-ID: <7937af93-9652-4032-93c9-7d7d8571c52b@redhat.com>
Date: Mon, 15 Sep 2025 16:05:46 -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 RFC -v2 11/11] cpuset: use partition_cpus_change for
 setting exclusive cpus

On 9/8/25 11:32 PM, Chen Ridong wrote:
> From: Chen Ridong <chenridong@...wei.com>
>
> Previous patches have refactored partition_cpus_change. Now replace the
> exclusive cpus setting logic with this helper function.
Nit: The term "refactor" usually mean updating the code of an existing 
function, sometimes extracting out code into new helper functions. In 
your case, partition_cpus_change() is a new helper function. This is 
also an issue in some of the earlier patches. I would prefer using 
phrase like "A previous patch has introduced a new helper function 
partition_cpus_change()"
>
> Signed-off-by: Chen Ridong <chenridong@...wei.com>
> ---
>   kernel/cgroup/cpuset.c | 29 ++---------------------------
>   1 file changed, 2 insertions(+), 27 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 785a2740b0ea..6a44dfabe9dd 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -2562,8 +2562,6 @@ static int update_exclusive_cpumask(struct cpuset *cs, struct cpuset *trialcs,
>   {
>   	int retval;
>   	struct tmpmasks tmp;
> -	struct cpuset *parent = parent_cs(cs);
> -	bool invalidate = false;
>   	bool force = false;
>   	int old_prs = cs->partition_root_state;
>   
> @@ -2595,32 +2593,9 @@ static int update_exclusive_cpumask(struct cpuset *cs, struct cpuset *trialcs,
>   	if (alloc_tmpmasks(&tmp))
>   		return -ENOMEM;
>   
> -	if (old_prs) {
> -		if (cpumask_empty(trialcs->effective_xcpus)) {
> -			invalidate = true;
> -			cs->prs_err = PERR_INVCPUS;
> -		} else if (prstate_housekeeping_conflict(old_prs, trialcs->effective_xcpus)) {
> -			invalidate = true;
> -			cs->prs_err = PERR_HKEEPING;
> -		} else if (tasks_nocpu_error(parent, cs, trialcs->effective_xcpus)) {
> -			invalidate = true;
> -			cs->prs_err = PERR_NOCPUS;
> -		}
> +	trialcs->prs_err = PERR_NONE;
> +	partition_cpus_change(cs, trialcs, &tmp);
>   
> -		if (is_remote_partition(cs)) {
> -			if (invalidate)
> -				remote_partition_disable(cs, &tmp);
> -			else
> -				remote_cpus_update(cs, trialcs->exclusive_cpus,
> -						   trialcs->effective_xcpus, &tmp);
> -		} else if (invalidate) {
> -			update_parent_effective_cpumask(cs, partcmd_invalidate,
> -							NULL, &tmp);
> -		} else {
> -			update_parent_effective_cpumask(cs, partcmd_update,
> -						trialcs->effective_xcpus, &tmp);
> -		}
> -	}
>   	spin_lock_irq(&callback_lock);
>   	cpumask_copy(cs->exclusive_cpus, trialcs->exclusive_cpus);
>   	cpumask_copy(cs->effective_xcpus, trialcs->effective_xcpus);
Reviewed-by: Waiman Long <longman@...hat.com>