linux-kernel - Re: [PATCH v6 1/3] x86/resctrl: Add mount option "mba_MBps

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Message-ID: <CALPaoCj_OvMzD8W9+jEORewwDquM6F-sOW32Ngcy+Gm6A1+OcQ@mail.gmail.com>
Date:   Fri, 8 Dec 2023 14:09:52 -0800
From:   Peter Newman <peternewman@...gle.com>
To:     Tony Luck <tony.luck@...el.com>
Cc:     Fenghua Yu <fenghua.yu@...el.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Jonathan Corbet <corbet@....net>,
        Shuah Khan <skhan@...uxfoundation.org>, x86@...nel.org,
        Shaopeng Tan <tan.shaopeng@...itsu.com>,
        James Morse <james.morse@....com>,
        Jamie Iles <quic_jiles@...cinc.com>,
        Babu Moger <babu.moger@....com>,
        Randy Dunlap <rdunlap@...radead.org>,
        linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
        patches@...ts.linux.dev
Subject: Re: [PATCH v6 1/3] x86/resctrl: Add mount option "mba_MBps_event"

On Fri, Dec 8, 2023 at 1:57 PM Tony Luck <tony.luck@...el.com> wrote:
>
> On Fri, Dec 08, 2023 at 10:17:08AM -0800, Peter Newman wrote:
> > Hi Tony,
> >
> > On Thu, Dec 7, 2023 at 11:56 AM Tony Luck <tony.luck@...el.com> wrote:
> > > @@ -2715,7 +2723,25 @@ static int rdt_parse_param(struct fs_context *fc, struct fs_parameter *param)
> > >         case Opt_mba_mbps:
> > >                 if (!supports_mba_mbps())
> > >                         return -EINVAL;
> > > -               ctx->enable_mba_mbps = true;
> > > +               if (is_mbm_local_enabled())
> > > +                       ctx->enable_mba_mbps_local = true;
> > > +               else
> > > +                       return -EINVAL;
> > > +               return 0;
> > > +       case Opt_mba_mbps_event:
> > > +               if (!supports_mba_mbps())
> > > +                       return -EINVAL;
> > > +               if (!strcmp("mbm_local_bytes", param->string)) {
> > > +                       if (!is_mbm_local_enabled())
> > > +                               return -EINVAL;
> > > +                       ctx->enable_mba_mbps_local = true;
> > > +               } else if (!strcmp("mbm_total_bytes", param->string)) {
> > > +                       if (!is_mbm_total_enabled())
> > > +                               return -EINVAL;
> > > +                       ctx->enable_mba_mbps_total = true;
> > > +               } else {
> > > +                       return -EINVAL;
> >
> > It looks like if I pass
> > "mba_MBps_event=mbm_total_bytes,mba_MBps_event=mbm_local_bytes" I can
> > set both flags true.
>
> That's going to be confusing. I'll add code to stop the user from
> passing both options.

Also kind of confusing, after reading the second patch, I realized
"mba_MBps_event=mbm_total_bytes,mba_MBps" also results in both being
set. If you're able to fail the mount operation if both flags somehow
get set, that would address this one too.

-Peter