linux-kernel - Re: [PATCH] ACPI: thermal: Do not call acpi_thermal

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Date:   Sun, 24 Jan 2021 14:40:15 +0100
From:   Stephen Berman <stephen.berman@....net>
To:     "Rafael J. Wysocki" <rafael@...nel.org>
Cc:     "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux ACPI <linux-acpi@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Zhang Rui <rui.zhang@...el.com>,
        Linux PM <linux-pm@...r.kernel.org>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: Re: [PATCH] ACPI: thermal: Do not call acpi_thermal_check() directly

On Fri, 22 Jan 2021 17:42:59 +0100 "Rafael J. Wysocki" <rafael@...nel.org> wrote:

> On Fri, Jan 22, 2021 at 5:39 PM Stephen Berman <stephen.berman@....net> wrote:
>>
>> On Fri, 22 Jan 2021 17:23:36 +0100 "Rafael J. Wysocki" <rafael@...nel.org> wrote:
>>
>> > On Thu, Jan 14, 2021 at 7:35 PM Rafael J. Wysocki <rjw@...ysocki.net> wrote:
>> >>
>> >> From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>> >>
>> >> Calling acpi_thermal_check() from acpi_thermal_notify() directly
>> >> is problematic if _TMP triggers Notify () on the thermal zone for
>> >> which it has been evaluated (which happens on some systems), because
>> >> it causes a new acpi_thermal_notify() invocation to be queued up
>> >> every time and if that takes place too often, an indefinite number of
>> >> pending work items may accumulate in kacpi_notify_wq over time.
>> >>
>> >> Besides, it is not really useful to queue up a new invocation of
>> >> acpi_thermal_check() if one of them is pending already.
>> >>
>> >> For these reasons, rework acpi_thermal_notify() to queue up a thermal
>> >> check instead of calling acpi_thermal_check() directly and only allow
>> >> one thermal check to be pending at a time.  Moreover, only allow one
>> >> acpi_thermal_check_fn() instance at a time to run
>> >> thermal_zone_device_update() for one thermal zone and make it return
>> >> early if it sees other instances running for the same thermal zone.
>> >>
>> >> While at it, fold acpi_thermal_check() into acpi_thermal_check_fn(),
>> >> as it is only called from there after the other changes made here.
>> >>
>> >> BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=208877
>> >> Reported-by: Stephen Berman <stephen.berman@....net>
>> >> Diagnosed-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
>> >> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
>> >
>> > Well, it's been over a week since this was posted.
>> >
>> > Does anyone have any comments?
>>
>> Sorry, I haven't been able to make time to test the patch yet, but I'll
>> try to do so this weekend.  Is it just the patch below that I should
>> apply, ignoring the previous patches you sent?
>
> Yes.
>
>> And can I apply it to the current mainline kernel?
>
> Yes, it should be applicable to the current mainline (at least as of 5.11-rc4).
>
> Thanks!

I've now updated my local repo to 5.11.0-rc4+, installed your patch,
rebuilt and installed the kernel, rebooted (without adding
'thermal.tzp=300' to the kernel command line), did some normal activity,
then ran 'shutdown -h now', and the machine did just that.  So your
patch seems to have fixed the problem I reported.  Many thanks!

Steve Berman