linux-kernel - Re: [PATCH][v2] PM / s2idle: Clear _TIF_POLLING

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Message-ID: <20200623015628.GA28671@chenyu-office.sh.intel.com>
Date:   Tue, 23 Jun 2020 09:56:28 +0800
From:   Chen Yu <yu.c.chen@...el.com>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     Peter Zijlstra <peterz@...radead.org>, Len Brown <lenb@...nel.org>,
        Daniel Lezcano <daniel.lezcano@...aro.org>,
        Ingo Molnar <mingo@...nel.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Rui Zhang <rui.zhang@...el.com>
Subject: Re: [PATCH][v2] PM / s2idle: Clear _TIF_POLLING_NRFLAG before
 suspend to idle

On Mon, Jun 22, 2020 at 09:45:35PM +0200, Rafael J. Wysocki wrote:
> On Mon, Jun 22, 2020 at 7:16 PM Chen Yu <yu.c.chen@...el.com> wrote:
> >
> > Hi Rafael,
> > On Mon, Jun 22, 2020 at 06:19:35PM +0200, Rafael J. Wysocki wrote:
> > [cut]
> > > > +{
> > > > +       if (!current_clr_polling_and_test())
> > > > +               s2idle_enter(drv, dev, index);
> > > > +
> > > > +       return index;
> > >
> > > Is the value returned here used at all?
> > >
> > It is not used for now IMO.
> > > >          */
> > > >         index = find_deepest_state(drv, dev, U64_MAX, 0, true);
> > > >         if (index > 0)
> > > > -               enter_s2idle_proper(drv, dev, index);
> > > > +               call_s2idle(drv, dev, index);
> > >
> > > I'm wondering why this can't be
> > >
> > >     if (index > 0 && !current_clr_polling_and_test())
> > >             enter_s2idle_proper(drv, dev, index);
> > >
> > Yes, it should be simpler, but I guess Peter was trying to
> > make call_s2idle() consistent with call_cpuidle(),
> > and also s2idle_enter() is analogous to cpuidle_enter().
> 
> So IMO it would be better to do the simplest fix first and then do the
> cleanup on top of it.
>
Okay, I'll do that.

Thanks,
Chenyu