linux-kernel - Re: [PATCH] ACPI / GED: unregister interrupts during shutdown

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Date:   Thu, 7 Dec 2017 00:19:25 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     Sinan Kaya <okaya@...eaurora.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Timur Tabi <timur@...eaurora.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        linux-arm-msm@...r.kernel.org,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] ACPI / GED: unregister interrupts during shutdown

Hi Greg,

On Wed, Dec 6, 2017 at 6:16 PM, Rafael J. Wysocki <rafael@...nel.org> wrote:
> On Wed, Dec 6, 2017 at 5:55 PM, Sinan Kaya <okaya@...eaurora.org> wrote:
>> On 12/6/2017 11:41 AM, Rafael J. Wysocki wrote:
>>> On Wed, Dec 6, 2017 at 5:11 PM, Sinan Kaya <okaya@...eaurora.org> wrote:
>>>> On 12/6/2017 9:57 AM, Sinan Kaya wrote:
>>>>>> Yes, it should, so I'm not sure why you need the list in the first place.
>>>>>>
>>>>>> Also it looks like something along the lines of devres_release_all()
>>>>>> should be sufficient.
>>>>> Good suggestion, let me test this.
>>>>>
>>>>
>>>> I tried to pull the code into GED but the API is not public. I also looked
>>>> at how it is used. I was afraid to mess up with the internals of base.c by
>>>> calling devres_release_all() externally first and by the driver framework
>>>> next. I moved away from this approach.
>>>
>>> Are you sure it is called by the core in the shutdown path?
>>
>> Sorry, I was thinking about a general case not the shutdown path. If we open
>> this API and have device drivers call it from arbitrary places; then we could
>> be opening a new can of worms that show up during device driver removal.

[cut]

>
> OK
>
> Anyway, it looks like something is missing in the core.
>
> You shouldn't really need to do all that dance in a driver.

We have a problem with the ACPI GED driver which essentially is a
platform driver requesting a number of interrupts and handling them by
dispatching a specific AML method.

It uses devm_request_threaded_irq() to request the interrupts, so it
doesn't need a ->remove() callback, but it turns out to need a
->shutdown() one to free all of these interrupts at the shutdown time.

While we can add a ->shutdown() callback to it, that essentially needs
to duplicate devres_release_all() somewhat.

Any suggestions what to do with that?

Thanks,
Rafael