All of lore.kernel.org
 help / color / mirror / Atom feed
From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
	Linux PM <linux-pm@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>,
	linux-omap <linux-omap@vger.kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Biju Das <biju.das@bp.renesas.com>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>
Subject: Re: [PATCH v2 ] PM-runtime: fix deadlock with ktime
Date: Tue, 5 Feb 2019 14:24:33 +0100	[thread overview]
Message-ID: <CAMuHMdWdbRpA_M4V1kigab6U8rSDgGYXtidiSU4MVdj5xarK8g@mail.gmail.com> (raw)
In-Reply-To: <CAPDyKFpyg7oGoDZA+=SG7R3yL874Geeqs5LWrsAf50csxsE05A@mail.gmail.com>

Hi Ulf,

On Wed, Jan 30, 2019 at 1:15 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:
> On Wed, 30 Jan 2019 at 12:16, Vincent Guittot
> <vincent.guittot@linaro.org> wrote:
> >
> > A deadlock has been seen when swicthing clocksources which use PM runtime.
> > The call path is:
> > change_clocksource
> >     ...
> >     write_seqcount_begin
> >     ...
> >     timekeeping_update
> >         ...
> >         sh_cmt_clocksource_enable
> >             ...
> >             rpm_resume
>
> Hmm, isn't this already a problem in genpd then?
>
> In genpd's ->runtime_resume() callback (genpd_runtime_resume()) we
> call ktime_get() to measure the latency of running the callback.
>
> Or, perhaps irq_safe_dev_in_no_sleep_domain() returns true for the
> genpd + device in question, which means the ktime thingy is skipped.
>
> Geert?

Correct. After adding

    dev_info(dev, "%s: pm_runtime_is_irq_safe = %d,
genpd_is_irq_safe(%s) = %d => %s\n", __func__,
pm_runtime_is_irq_safe(dev), genpd->name, genpd_is_irq_safe(genpd),
ret ? "true" : "false");

I see on R-Car M2-W:

    sh_cmt ffca0000.timer: irq_safe_dev_in_no_sleep_domain:
pm_runtime_is_irq_safe = 1, genpd_is_irq_safe(always-on) = 0 => true

For all other devices, the result is false.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

WARNING: multiple messages have this Message-ID (diff)
From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
	Linux PM <linux-pm@vger.kernel.org>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Biju Das <biju.das@bp.renesas.com>,
	Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
	linux-omap <linux-omap@vger.kernel.org>,
	Linux ARM <linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH v2 ] PM-runtime: fix deadlock with ktime
Date: Tue, 5 Feb 2019 14:24:33 +0100	[thread overview]
Message-ID: <CAMuHMdWdbRpA_M4V1kigab6U8rSDgGYXtidiSU4MVdj5xarK8g@mail.gmail.com> (raw)
In-Reply-To: <CAPDyKFpyg7oGoDZA+=SG7R3yL874Geeqs5LWrsAf50csxsE05A@mail.gmail.com>

Hi Ulf,

On Wed, Jan 30, 2019 at 1:15 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:
> On Wed, 30 Jan 2019 at 12:16, Vincent Guittot
> <vincent.guittot@linaro.org> wrote:
> >
> > A deadlock has been seen when swicthing clocksources which use PM runtime.
> > The call path is:
> > change_clocksource
> >     ...
> >     write_seqcount_begin
> >     ...
> >     timekeeping_update
> >         ...
> >         sh_cmt_clocksource_enable
> >             ...
> >             rpm_resume
>
> Hmm, isn't this already a problem in genpd then?
>
> In genpd's ->runtime_resume() callback (genpd_runtime_resume()) we
> call ktime_get() to measure the latency of running the callback.
>
> Or, perhaps irq_safe_dev_in_no_sleep_domain() returns true for the
> genpd + device in question, which means the ktime thingy is skipped.
>
> Geert?

Correct. After adding

    dev_info(dev, "%s: pm_runtime_is_irq_safe = %d,
genpd_is_irq_safe(%s) = %d => %s\n", __func__,
pm_runtime_is_irq_safe(dev), genpd->name, genpd_is_irq_safe(genpd),
ret ? "true" : "false");

I see on R-Car M2-W:

    sh_cmt ffca0000.timer: irq_safe_dev_in_no_sleep_domain:
pm_runtime_is_irq_safe = 1, genpd_is_irq_safe(always-on) = 0 => true

For all other devices, the result is false.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

  reply	other threads:[~2019-02-05 13:24 UTC|newest]

Thread overview: 36+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-30 11:16 [PATCH v2 ] PM-runtime: fix deadlock with ktime Vincent Guittot
2019-01-30 11:16 ` Vincent Guittot
2019-01-30 12:14 ` Ulf Hansson
2019-01-30 12:14   ` Ulf Hansson
2019-01-30 12:14   ` Ulf Hansson
2019-02-05 13:24   ` Geert Uytterhoeven [this message]
2019-02-05 13:24     ` Geert Uytterhoeven
2019-02-05 13:40     ` Ulf Hansson
2019-02-05 13:40       ` Ulf Hansson
2019-01-30 13:06 ` Rafael J. Wysocki
2019-01-30 13:06   ` Rafael J. Wysocki
2019-01-30 13:18   ` Vincent Guittot
2019-01-30 13:18     ` Vincent Guittot
2019-01-30 19:39     ` Ladislav Michl
2019-01-30 19:39       ` Ladislav Michl
2019-01-30 17:26   ` [PATCH v3] " Vincent Guittot
2019-01-30 17:26     ` Vincent Guittot
2019-01-30 21:53     ` Rafael J. Wysocki
2019-01-30 21:53       ` Rafael J. Wysocki
2019-01-30 21:53       ` Rafael J. Wysocki
2019-02-01 15:02       ` Biju Das
2019-02-01 15:02         ` Biju Das
2019-02-01 15:28         ` Vincent Guittot
2019-02-01 15:28           ` Vincent Guittot
2019-02-01 15:44           ` Biju Das
2019-02-01 15:44             ` Biju Das
2019-02-01 15:48             ` Vincent Guittot
2019-02-01 15:48               ` Vincent Guittot
2019-02-01 15:52               ` Vincent Guittot
2019-02-01 15:52                 ` Vincent Guittot
2019-02-04  9:29                 ` Biju Das
2019-02-04  9:29                   ` Biju Das
2019-02-01 15:45           ` Vincent Guittot
2019-02-01 15:45             ` Vincent Guittot
2019-01-30 21:32   ` [PATCH v2 ] " Ladislav Michl
2019-01-30 21:32     ` Ladislav Michl

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=CAMuHMdWdbRpA_M4V1kigab6U8rSDgGYXtidiSU4MVdj5xarK8g@mail.gmail.com \
    --to=geert@linux-m68k.org \
    --cc=biju.das@bp.renesas.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-omap@vger.kernel.org \
    --cc=linux-pm@vger.kernel.org \
    --cc=linux-renesas-soc@vger.kernel.org \
    --cc=rjw@rjwysocki.net \
    --cc=ulf.hansson@linaro.org \
    --cc=vincent.guittot@linaro.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.