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

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Message-ID: <20200622171759.GA26527@chenyu-office.sh.intel.com>
Date:   Tue, 23 Jun 2020 01:18:00 +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

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().

Thanks,
Chenyu