MIME-Version: 1.0
References: <20230211064527.3481754-1-jstultz@google.com> <20230211064527.3481754-2-jstultz@google.com>
 <CAOf5uwnW1u=nfFnj3C8kCVmhgwRaVh6sHZR1RGnXdbrCNpkGVg@mail.gmail.com>
 <87o7porea9.ffs@tglx> <CAOf5uwmhtQ8GXhMiE-Y3-wgL5=xfjOv0Tpq1vqPB8p=LyZHBmw@mail.gmail.com>
 <CAOf5uwmpayJwpAFzUS6qsCgdpyek1f-2t2t9YNr76vnRjSC8=w@mail.gmail.com>
 <87a618qlcp.ffs@tglx> <CAOf5uw=a2RYYFj+4_WOX+KaF_FCXSsUgfM+T2m2XjVuqKMdooA@mail.gmail.com>
 <87sff0ox1a.ffs@tglx> <CAOf5uwmZWZij1tKUFUWKSKqyph4OYe6C3HdA8TQtrB7ztOdC-A@mail.gmail.com>
 <874jrfq3jw.ffs@tglx> <CAOf5uw=+yZiTXGyjDgiw_w9yZZ5Pz3JQpykdCyFfbpNBTz+rXA@mail.gmail.com>
In-Reply-To: <CAOf5uw=+yZiTXGyjDgiw_w9yZZ5Pz3JQpykdCyFfbpNBTz+rXA@mail.gmail.com>
From:   Michael Nazzareno Trimarchi <michael@amarulasolutions.com>
Date:   Fri, 24 Feb 2023 11:02:49 +0100
Message-ID: <CAOf5uwmqLkFDAjQdSJF8zXHjoz1P-2-Fp1L6orRHsAa6x89EHA@mail.gmail.com>
Subject: Re: [RFC][PATCH 2/2] time: alarmtimer: Use TASK_FREEZABLE to cleanup
 freezer handling
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     John Stultz <jstultz@google.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Stephen Boyd <sboyd@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
        Michael <michael@mipisi.de>, kernel-team@android.com,
        Peter Zijlstra <peterz@infradead.org>,
        "Rafael J. Wysocki" <rafael@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Precedence: bulk

Hi Thomas

On Tue, Feb 21, 2023 at 8:10 AM Michael Nazzareno Trimarchi
<michael@amarulasolutions.com> wrote:
>
> Hi
>
> On Tue, Feb 21, 2023 at 1:12 AM Thomas Gleixner <tglx@linutronix.de> wrote:
> >
> > Michael!
> >
> > On Mon, Feb 20 2023 at 22:32, Michael Nazzareno Trimarchi wrote:
> > > On Mon, Feb 20, 2023 at 10:18 PM Thomas Gleixner <tglx@linutronix.de> wrote:
> > >>   * alarmtimer_fired - Handles alarm hrtimer being fired.
> > >> @@ -194,6 +196,8 @@ static enum hrtimer_restart alarmtimer_f
> > >>         int ret = HRTIMER_NORESTART;
> > >>         int restart = ALARMTIMER_NORESTART;
> > >>
> > >> +       atomic_inc(&alarmtimer_wakeup);
> > >> +
> > >
> > >        ptr->it_active = 0;
> > >         if (ptr->it_interval) {
> > >                 atomic_inc(&alarmtimer_wakeup);
> > >                 si_private = ++ptr->it_requeue_pending;
> > >         }
> > >
> > > Should I not go to the alarm_handle_timer? and only if it's a periodic
> > > one?
> >
> > Why?
> >
>
> You are right. I will pay more attention to my reply.
>

I get time to test it and if the system suspend to ram we need to catch:

case PM_SUSPEND_PREPARE:
case PM_POST_SUSPEND:

Michael

> Michael
>
> > Any alarmtimer which hits that window has exactly the same problem.
> >
> > It's not restricted to periodic timers. Why would a dropped one-shot
> > wakeup be acceptable?
> >
> > It's neither restricted to posix timers. If a clock_nanosleep(ALARM)
> > expires in that window then the task wake up will just end up in the
> > /dev/null bucket for the very same reason. Why would this be correct?
> >
> > Hmm?
> >
> > <GRMBL>
> > > Michael
> > >
> > >>         spin_lock_irqsave(&base->lock, flags);
> >
> > <SNIP>Tons of wasted electrons</SNIP>
> >
> > Can you please trim your replies?
> >
> > </GRMBL>
> >
> > Thanks,
> >
> >         tglx