linux-kernel - Re: power-off delay/hang due to commit 6d25be57 (mainline)

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Date:   Tue, 14 Jul 2020 15:54:57 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Cc:     Zhang Rui <rui.zhang@...el.com>,
        Robert Moore <robert.moore@...el.com>,
        Erik Kaneda <erik.kaneda@...el.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Len Brown <lenb@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Stephen Berman <stephen.berman@....net>,
        "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" <devel@...ica.org>
Subject: Re: power-off delay/hang due to commit 6d25be57 (mainline)

On Tue, Jul 14, 2020 at 3:44 PM Sebastian Andrzej Siewior
<bigeasy@...utronix.de> wrote:>
> On 2020-06-24 23:49:52 [+0200], Stephen Berman wrote:
>
> Let me summarize the thread here:
>
> On Stephen's system, ACPI informs the thermal zone driver to poll the
> temperature every second and the driver does so.
> The driver queries the temperature by invoking acpi_evaluate_integer()
> which invokes (at some point) acpi_ev_queue_notify_request().

Well, I don't quite see how acpi_ev_queue_notify_request() can be
invoked from the acpi_evaluate_integer() code path.

Do you have a call trace showing that?

> This then invokes acpi_os_execute_deferred() via
>     queue_work_on(, kacpi_notify_wq, )
>
> acpi_os_execute_deferred() invokes acpi_ev_notify_dispatch() and this is
> no longer synchronised with the initial acpi_evaluate_integer() request.

That indeed would be the case, but I first need to understand what's
going on with the acpi_evaluate_integer() causing a Notify () to be
queued up.

Cheers!