linux-kernel - Re: [PATCH] arch_topology: Do not set llc_sibling if llc

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Message-ID: <CAHp75Vc-frdJSAMxK1YpHwmPa_-0fTpRxq=QObcux3Jt=5+9kw@mail.gmail.com>
Date:   Mon, 11 Apr 2022 18:07:45 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Qing Wang <wangqing@...o.com>
Cc:     Sudeep Holla <sudeep.holla@....com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        "Rafael J. Wysocki" <rafael@...nel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] arch_topology: Do not set llc_sibling if llc_id is invalid

On Mon, Apr 11, 2022 at 12:10 PM Qing Wang <wangqing@...o.com> wrote:
>
> From: Wang Qing <wangqing@...o.com>
>
> When ACPI is not enabled, cpuid_topo->llc_id = cpu_topo->llc_id = -1, which
> will set llc_sibling 0xff(...), this is misleading.

Shouldn't it be a Fixes tag then?

> Don't set llc_sibling(default 0) if we don't know the cache topology.

...

> -               if (cpuid_topo->llc_id == cpu_topo->llc_id) {
> +               if (cpu_topo->llc_id != -1 && cpuid_topo->llc_id == cpu_topo->llc_id) {

I'm wondering if more strict check is better here, i.e.

               if (cpu_topo->llc_id >= 0 && cpuid_topo->llc_id ==
cpu_topo->llc_id) {

>                         cpumask_set_cpu(cpu, &cpuid_topo->llc_sibling);
>                         cpumask_set_cpu(cpuid, &cpu_topo->llc_sibling);
>                 }

-- 
With Best Regards,
Andy Shevchenko