Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200615145130.bcdidqkp6w23xb6c@linutronix.de>
 <87tuzbh482.fsf@gmx.net> <20200616073827.vysntufld3ves666@linutronix.de>
 <87o8pjh1i0.fsf@gmx.net> <20200616155501.psduxnisltitodme@linutronix.de>
 <871rmesqkk.fsf@gmx.net> <20200617142734.mxwfoblufmo6li5e@linutronix.de>
 <87ftatqu07.fsf@gmx.net> <20200624201156.xu6hel3drnhno6c3@linutronix.de>
 <87ftak2kxr.fsf@rub.de> <20200714134410.3odqfvjq6rndjjf6@linutronix.de>
In-Reply-To: <20200714134410.3odqfvjq6rndjjf6@linutronix.de>
From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Tue, 14 Jul 2020 15:54:57 +0200
Message-ID: <CAJZ5v0hZSUkEMCszDADGWk-v0xNEiDE45B3CHLi05BX6rPfm6g@mail.gmail.com>
Subject: Re: power-off delay/hang due to commit 6d25be57 (mainline)
To:     Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc:     Zhang Rui <rui.zhang@intel.com>,
        Robert Moore <robert.moore@intel.com>,
        Erik Kaneda <erik.kaneda@intel.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        Len Brown <lenb@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Peter Zijlstra <peterz@infradead.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
        Stephen Berman <stephen.berman@gmx.net>,
        "open list:ACPI COMPONENT ARCHITECTURE (ACPICA)" <devel@acpica.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Tue, Jul 14, 2020 at 3:44 PM Sebastian Andrzej Siewior
<bigeasy@linutronix.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!