linux-kernel - Re: [PATCH 1/3] cacheinfo: Add function to get cacheinfo for a given (cpu, cachelevel)

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Date: Mon, 3 Jun 2024 11:06:53 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Greg Kroah-Hartman
	<gregkh@...uxfoundation.org>, Andrew Morton <akpm@...ux-foundation.org>,
	Thomas Gleixner <tglx@...utronix.de>, Borislav Petkov <bp@...en8.de>
CC: Fenghua Yu <fenghua.yu@...el.com>, Maciej Wieczor-Retman
	<maciej.wieczor-retman@...el.com>, Peter Newman <peternewman@...gle.com>,
	James Morse <james.morse@....com>, Babu Moger <babu.moger@....com>, "Drew
 Fustini" <dfustini@...libre.com>, Dave Martin <Dave.Martin@....com>,
	<linux-kernel@...r.kernel.org>, <patches@...ts.linux.dev>
Subject: Re: [PATCH 1/3] cacheinfo: Add function to get cacheinfo for a given
 (cpu, cachelevel)

Hi Tony,

On 5/31/24 12:57 PM, Tony Luck wrote:
> Resctrl code open codes a search for information about a given cache
> level in a couple of places (and more are on the way).
> 
> Provide a new inline function get_cpu_cacheinfo_level() in
> <linux/cacheinfo.h> to do the search and return a pointer to
> the cacheinfo structure.
> 
> Simplify the existing get_cpu_cacheinfo_id() by using this new
> function to do the search.
> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---
>   include/linux/cacheinfo.h | 21 ++++++++++++++++-----
>   1 file changed, 16 insertions(+), 5 deletions(-)
> 
> diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h
> index 2cb15fe4fe12..301b0b24f446 100644
> --- a/include/linux/cacheinfo.h
> +++ b/include/linux/cacheinfo.h
> @@ -113,10 +113,10 @@ int acpi_get_cache_info(unsigned int cpu,
>   const struct attribute_group *cache_get_priv_group(struct cacheinfo *this_leaf);
>   
>   /*
> - * Get the id of the cache associated with @cpu at level @level.
> + * Get the cacheinfo structure for cache associated with @cpu at level @level.

"for cache" -> "for the cache"?

>    * cpuhp lock must be held.
>    */
> -static inline int get_cpu_cacheinfo_id(int cpu, int level)
> +static inline struct cacheinfo *get_cpu_cacheinfo_level(int cpu, int level)
>   {
>   	struct cpu_cacheinfo *ci = get_cpu_cacheinfo(cpu);
>   	int i;
> @@ -124,12 +124,23 @@ static inline int get_cpu_cacheinfo_id(int cpu, int level)
>   	for (i = 0; i < ci->num_leaves; i++) {
>   		if (ci->info_list[i].level == level) {
>   			if (ci->info_list[i].attributes & CACHE_ID)
> -				return ci->info_list[i].id;
> -			return -1;
> +				return &ci->info_list[i];
> +			return NULL;
>   		}
>   	}
>   
> -	return -1;
> +	return NULL;
> +}
> +
> +/*
> + * Get the id of the cache associated with @cpu at level @level.
> + * cpuhp lock must be held.
> + */
> +static inline int get_cpu_cacheinfo_id(int cpu, int level)
> +{
> +	struct cacheinfo *ci = get_cpu_cacheinfo_level(cpu, level);
> +
> +	return ci ? ci->id : -1;
>   }
>   
>   #ifdef CONFIG_ARM64

Just the one nitpick from me.
Thank you.

| Reviewed-by: Reinette Chatre <reinette.chatre@...el.com>

Reinette