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

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Message-ID: <CAJZ5v0jcFqG=Jd19ms7XQMR+rGfdKTEaN7SK91DPzBa=xcMY1w@mail.gmail.com>
Date:   Tue, 5 Dec 2017 23:18:44 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Sinan Kaya <okaya@...eaurora.org>
Cc:     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

On Tue, Dec 5, 2017 at 10:01 PM, Sinan Kaya <okaya@...eaurora.org> wrote:
> Some GED interrupts could be pending by the time we are doing a reboot.
>
> Even though GED driver uses devm_request_irq() to register the interrupt
> handler, the handler is not being freed on time during a shutdown since
> the driver is missing a shutdown callback.
>
> If the ACPI handler is no longer available, this causes an interrupt
> storm and delays shutdown.
>
> Register a shutdown callback and manually free the interrupts.
>
> Signed-off-by: Sinan Kaya <okaya@...eaurora.org>
> ---
>  drivers/acpi/evged.c | 36 +++++++++++++++++++++++++++++++++---
>  1 file changed, 33 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/acpi/evged.c b/drivers/acpi/evged.c
> index 46f0603..dde50ea 100644
> --- a/drivers/acpi/evged.c
> +++ b/drivers/acpi/evged.c
> @@ -1,7 +1,7 @@
>  /*
>   * Generic Event Device for ACPI.
>   *
> - * Copyright (c) 2016, The Linux Foundation. All rights reserved.
> + * Copyright (c) 2016-2017, The Linux Foundation. All rights reserved.

Why are you changing this?

>   *
>   * This program is free software; you can redistribute it and/or modify
>   * it under the terms of the GNU General Public License version 2 and
> @@ -49,6 +49,11 @@
>
>  #define MODULE_NAME    "acpi-ged"
>
> +struct acpi_ged_device {
> +       struct device *dev;
> +       struct list_head event_list;
> +};
> +
>  struct acpi_ged_event {
>         struct list_head node;
>         struct device *dev;
> @@ -76,7 +81,8 @@ static acpi_status acpi_ged_request_interrupt(struct acpi_resource *ares,
>         unsigned int irq;
>         unsigned int gsi;
>         unsigned int irqflags = IRQF_ONESHOT;
> -       struct device *dev = context;
> +       struct acpi_ged_device *geddev = context;
> +       struct device *dev = geddev->dev;
>         acpi_handle handle = ACPI_HANDLE(dev);
>         acpi_handle evt_handle;
>         struct resource r;
> @@ -122,29 +128,53 @@ static acpi_status acpi_ged_request_interrupt(struct acpi_resource *ares,
>                 return AE_ERROR;
>         }
>
> +       dev_info(dev, "GED listening GSI %u @ IRQ %u\n", gsi, irq);

Why dev_info()?

> +       list_add_tail(&event->node, &geddev->event_list);
>         return AE_OK;
>  }
>
>  static int ged_probe(struct platform_device *pdev)
>  {
> +       struct acpi_ged_device *geddev;
>         acpi_status acpi_ret;
>
> +       geddev = devm_kzalloc(&pdev->dev, sizeof(*geddev), GFP_KERNEL);
> +       if (!geddev)
> +               return -ENOMEM;
> +
> +       geddev->dev = &pdev->dev;
> +       INIT_LIST_HEAD(&geddev->event_list);
>         acpi_ret = acpi_walk_resources(ACPI_HANDLE(&pdev->dev), "_CRS",
> -                                      acpi_ged_request_interrupt, &pdev->dev);
> +                                      acpi_ged_request_interrupt, geddev);
>         if (ACPI_FAILURE(acpi_ret)) {
>                 dev_err(&pdev->dev, "unable to parse the _CRS record\n");
>                 return -EINVAL;
>         }
> +       platform_set_drvdata(pdev, geddev);
>
>         return 0;
>  }
>
> +static void ged_remove(struct platform_device *pdev)
> +{
> +       struct acpi_ged_device *geddev = platform_get_drvdata(pdev);
> +       struct acpi_ged_event *event, *next;
> +
> +       list_for_each_entry_safe(event, next, &geddev->event_list, node) {
> +               devm_free_irq(geddev->dev, event->irq, event);
> +               list_del(&event->node);
> +               dev_info(geddev->dev, "GED releasing GSI %u @ IRQ %u\n",
> +                        event->gsi, event->irq);

dev_dbg() and that if you really need it.

> +       }
> +}
> +
>  static const struct acpi_device_id ged_acpi_ids[] = {
>         {"ACPI0013"},
>         {},
>  };
>
>  static struct platform_driver ged_driver = {
> +       .shutdown = ged_remove,

That ged_remove really should be called ged_shutdown.  It is confusing
as is, because there is a ->remove callback in the structure too.

>         .probe = ged_probe,
>         .driver = {
>                 .name = MODULE_NAME,
> --

Overall, it looks like we should just unbind the driver from all
devices on shutdown.

Thanks,
Rafael