linux-kernel - Re: [PATCH -next RFC -v2 07/11] cpuset: refactor out validate

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Message-ID: <90fb9914-3c6f-4d2a-8512-cebcaa5ddbb6@redhat.com>
Date: Mon, 15 Sep 2025 14:53:45 -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 07/11] cpuset: refactor out
 validate_partition

On 9/8/25 11:32 PM, Chen Ridong wrote:
> From: Chen Ridong <chenridong@...wei.com>
>
> Refactor the validate_partition function to handle cpuset partition
> validation when modifying cpuset.cpus. This refactoring also makes the
> function reusable for handling cpuset.cpus.exclusive updates in subsequent
> patches.
>
> Signed-off-by: Chen Ridong <chenridong@...wei.com>
> ---
>   kernel/cgroup/cpuset.c | 48 +++++++++++++++++++++++++++++++-----------
>   1 file changed, 36 insertions(+), 12 deletions(-)
>
> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c
> index 389dfd5be6c8..770b33e30576 100644
> --- a/kernel/cgroup/cpuset.c
> +++ b/kernel/cgroup/cpuset.c
> @@ -2386,6 +2386,37 @@ static int parse_cpuset_cpulist(const char *buf, struct cpumask *out_mask)
>   	return 0;
>   }
>   
> +/**
> + * validate_partition - Validate a cpuset partition configuration
> + * @cs: The cpuset to validate
> + * @trialcs: The trial cpuset containing proposed configuration changes
> + *
> + * If any validation check fails, the appropriate error code is set in the
> + * cpuset's prs_err field.
> + *
> + * Return: PRS error code (0 if valid, non-zero error code if invalid)
> + */
> +static enum prs_errcode validate_partition(struct cpuset *cs, struct cpuset *trialcs)
> +{
> +	struct cpuset *parent = parent_cs(cs);
> +
> +	if (cs_is_member(trialcs))
> +		return PERR_NONE;
> +
> +	if (cpumask_empty(trialcs->effective_xcpus))
> +		return PERR_INVCPUS;
> +
> +	if (prstate_housekeeping_conflict(trialcs->partition_root_state,
> +					  trialcs->effective_xcpus))
> +		return PERR_HKEEPING;
> +
> +	if (tasks_nocpu_error(parent, cs, trialcs->effective_xcpus))
> +		return PERR_NOCPUS;
> +
> +	return PERR_NONE;
> +}
> +
> +
>   /**
>    * update_cpumask - update the cpus_allowed mask of a cpuset and all tasks in it
>    * @cs: the cpuset to consider
> @@ -2401,6 +2432,7 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
>   	bool invalidate = false;
>   	bool force = false;
>   	int old_prs = cs->partition_root_state;
> +	enum prs_errcode prs_err;
>   
>   	retval = parse_cpuset_cpulist(buf, trialcs->cpus_allowed);
>   	if (retval < 0)
> @@ -2415,18 +2447,10 @@ static int update_cpumask(struct cpuset *cs, struct cpuset *trialcs,
>   
>   	compute_trialcs_excpus(trialcs, cs);
>   
> -	if (old_prs) {
> -		if (is_partition_valid(cs) &&
> -		    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;
> -		}
> +	prs_err = validate_partition(cs, trialcs);
> +	if (prs_err) {
> +		invalidate = true;
> +		cs->prs_err = prs_err;
>   	}
>   
>   	/*
Reviewed-by: Waiman Long <longman@...hat.com>