Subject: Re: [PATCH v2 0/4] ACPI: SBS: Fix various issues
To:     "Rafael J. Wysocki" <rafael@kernel.org>
Cc:     lenb@kernel.org, linux-acpi@vger.kernel.org,
        linux-kernel@vger.kernel.org
References: <20230225115144.31212-1-W_Armin@gmx.de>
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 <CAJZ5v0itUSnsxgdvw39e+YZWe4jTHA1fLjw3HZSKHTkp+eLHwQ@mail.gmail.com>
From:   Armin Wolf <W_Armin@gmx.de>
Message-ID: <1de16fdb-e6e2-57eb-b074-cdd5473172ba@gmx.de>
Date:   Wed, 15 Mar 2023 00:04:34 +0100
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Precedence: bulk

Am 14.03.23 um 20:49 schrieb Rafael J. Wysocki:

> On Sun, Mar 12, 2023 at 6:15=E2=80=AFPM Armin Wolf <W_Armin@gmx.de> wrot=
e:
>> Am 25.02.23 um 12:51 schrieb Armin Wolf:
>>
>>> On my Acer Travelmate 4002WLMi, the system locks up upon
>>> suspend/shutdown. After a lot of research, it turned out
>>> that the sbs module was the culprit. The driver would not
>>> correctly mask out the value used to select a battery using
>>> the "Smart Battery Selector" (subset of the "Smart Battery Manager").
>>> This accidentally caused a invalid power source to be selected,
>>> which was automatically corrected by the selector. Upon
>>> notifing the host about the corrected power source, some batteries
>>> would be selected for re-reading, causing a endless loop.
>>> This would lead to some workqueues filling up, which caused the
>>> lockup upon suspend/shutdown.
>>>
>>> The first three patches fix a stacktrace on module removal caused
>>> by some locking issues. The last patch finally fixes the
>>> suspend/shutdown issues.
>>>
>>> As a side note: This was the first machine on which i installed Linux,
>>> to finally fixing this took ~5 years of tinkering.
>> What is the status of this patchset? Should i use a SRCU notifier chain
>> for the query notifiers? I would really like to see this getting fixed,
>> as it prevents me from using linux on this machine.
> I'm not entirely convinced about the query notifiers idea TBH.

I already thought about just flushing the query workqueue, but acpi_ec_rem=
ove_query_handler()
would still also remove query handlers installed to handle _Qxx methods. T=
his might cause errors,
as for example on the Acer Travelmate 4002WLMI, the SMBUS query handler (_=
Q20) resets the SMBUS
alert bit in case no EC SMBus driver is overriding it.
Is there any specific reason for your dislike of the query notifiers? I co=
uld turn them into
SRCU call chains to avoid performance issues.

Armin Wolf