linux-kernel - Re: [PATCH v7 06/31] x86/resctrl: Move L3 initialization into new helper function

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Message-ID: <6ac15beb-7306-4507-b88b-b6f6cca66def@intel.com>
Date: Fri, 25 Jul 2025 16:21:57 -0700
From: Reinette Chatre <reinette.chatre@...el.com>
To: Tony Luck <tony.luck@...el.com>, Fenghua Yu <fenghuay@...dia.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>, Anil Keshavamurthy <anil.s.keshavamurthy@...el.com>,
	Chen Yu <yu.c.chen@...el.com>
CC: <x86@...nel.org>, <linux-kernel@...r.kernel.org>,
	<patches@...ts.linux.dev>
Subject: Re: [PATCH v7 06/31] x86/resctrl: Move L3 initialization into new
 helper function

Hi Tony,

On 7/11/25 4:53 PM, Tony Luck wrote:

Missing context and problem description.

> To prepare for additional types of monitoring domains, move open coded L3
> resource monitoring domain initialization from domain_add_cpu_mon() into
> a new helper function l3_mon_domain_setup() called by domain_add_cpu_mon().

Please drop "function" that is unnecessary when using ().
(this highlights to consider my proposals critically as this confirms how easily
I too get it wrong)

> 
> Signed-off-by: Tony Luck <tony.luck@...el.com>
> ---

...

> +static void domain_add_cpu_mon(int cpu, struct rdt_resource *r)
> +{
> +	int id = get_domain_id_from_scope(cpu, r->mon_scope);
> +	struct list_head *add_pos = NULL;
> +	struct rdt_domain_hdr *hdr;
> +
> +	lockdep_assert_held(&domain_list_lock);
> +
> +	if (id < 0) {
> +		pr_warn_once("Can't find monitor domain id for CPU:%d scope:%d for resource %s\n",
> +			     cpu, r->mon_scope, r->name);
> +		return;
> +	}
> +
> +	hdr = resctrl_find_domain(&r->mon_domains, id, &add_pos);
> +	if (hdr) {
> +		if (!domain_header_is_valid(hdr, RESCTRL_MON_DOMAIN, r->rid))
> +			return;
> +		cpumask_set_cpu(cpu, &hdr->cpu_mask);
> +
> +		return;
> +	}
> +
> +	switch (r->rid) {
> +	case RDT_RESOURCE_L3:
> +		l3_mon_domain_setup(cpu, id, r, add_pos);
> +		break;
> +	default:
> +		WARN_ON_ONCE(1);

Please add a "break". For consistency, when compared with the changes to
partner domain_remove_cpu_mon() in the next patch I'd vote for how the
default branch in domain_remove_cpu_mon() looks.

Reinette