linux-kernel - Re: [PATCH v5 05/10] acpi/battery: Move handler installing logic to driver

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Message-ID: <CAJZ5v0i1-7p-V0nFHoNWHDXRZ-xvVwTXJKM387PTP1d4k7Wrdg@mail.gmail.com>
Date:   Thu, 29 Jun 2023 18:05:54 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Michal Wilczynski <michal.wilczynski@...el.com>
Cc:     linux-acpi@...r.kernel.org, rafael@...nel.org,
        dan.j.williams@...el.com, vishal.l.verma@...el.com,
        lenb@...nel.org, dave.jiang@...el.com, ira.weiny@...el.com,
        rui.zhang@...el.com, linux-kernel@...r.kernel.org,
        nvdimm@...ts.linux.dev,
        "Rafael J . Wysocki" <rafael.j.wysocki@...el.com>
Subject: Re: [PATCH v5 05/10] acpi/battery: Move handler installing logic to driver

On Fri, Jun 16, 2023 at 6:51 PM Michal Wilczynski
<michal.wilczynski@...el.com> wrote:
>
> Currently logic for installing notifications from ACPI devices is
> implemented using notify callback in struct acpi_driver. Preparations
> are being made to replace acpi_driver with more generic struct
> platform_driver, which doesn't contain notify callback. Furthermore
> as of now handlers are being called indirectly through
> acpi_notify_device(), which decreases performance.
>
> Call acpi_dev_install_notify_handler() at the end of .add() callback.
> Call acpi_dev_remove_notify_handler() at the beginning of .remove()
> callback. Change arguments passed to the notify function to match with
> what's required by acpi_install_notify_handler(). Remove .notify
> callback initialization in acpi_driver.
>
> While at it, fix lack of whitespaces in .remove() callback.
>
> Suggested-by: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
> Signed-off-by: Michal Wilczynski <michal.wilczynski@...el.com>
> ---
>  drivers/acpi/battery.c | 30 ++++++++++++++++++++++++------
>  1 file changed, 24 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
> index 9c67ed02d797..6337e7b1f6e1 100644
> --- a/drivers/acpi/battery.c
> +++ b/drivers/acpi/battery.c
> @@ -1034,11 +1034,14 @@ static void acpi_battery_refresh(struct acpi_battery *battery)
>  }
>
>  /* Driver Interface */
> -static void acpi_battery_notify(struct acpi_device *device, u32 event)
> +static void acpi_battery_notify(acpi_handle handle, u32 event, void *data)
>  {
> -       struct acpi_battery *battery = acpi_driver_data(device);
> +       struct acpi_device *device = data;
> +       struct acpi_battery *battery;
>         struct power_supply *old;
>
> +       battery = acpi_driver_data(device);
> +
>         if (!battery)
>                 return;
>         old = battery->bat;
> @@ -1212,13 +1215,23 @@ static int acpi_battery_add(struct acpi_device *device)
>
>         device_init_wakeup(&device->dev, 1);
>
> -       return result;
> +       result = acpi_dev_install_notify_handler(device,
> +                                                ACPI_ALL_NOTIFY,
> +                                                acpi_battery_notify);
> +       if (result)
> +               goto fail_deinit_wakup_and_unregister;

You could call the label "fail_pm", for example, which would be more
concise and so slightly easier to follow, without any loss of clarity
AFAICS.

> +
> +       return 0;
>
> +fail_deinit_wakup_and_unregister:
> +       device_init_wakeup(&device->dev, 0);
> +       unregister_pm_notifier(&battery->pm_nb);
>  fail:
>         sysfs_remove_battery(battery);
>         mutex_destroy(&battery->lock);
>         mutex_destroy(&battery->sysfs_lock);
>         kfree(battery);
> +
>         return result;
>  }
>
> @@ -1228,10 +1241,17 @@ static void acpi_battery_remove(struct acpi_device *device)
>
>         if (!device || !acpi_driver_data(device))
>                 return;
> -       device_init_wakeup(&device->dev, 0);
> +
>         battery = acpi_driver_data(device);
> +
> +       acpi_dev_remove_notify_handler(device,
> +                                      ACPI_ALL_NOTIFY,
> +                                      acpi_battery_notify);
> +
> +       device_init_wakeup(&device->dev, 0);
>         unregister_pm_notifier(&battery->pm_nb);
>         sysfs_remove_battery(battery);
> +
>         mutex_destroy(&battery->lock);
>         mutex_destroy(&battery->sysfs_lock);
>         kfree(battery);
> @@ -1264,11 +1284,9 @@ static struct acpi_driver acpi_battery_driver = {
>         .name = "battery",
>         .class = ACPI_BATTERY_CLASS,
>         .ids = battery_device_ids,
> -       .flags = ACPI_DRIVER_ALL_NOTIFY_EVENTS,
>         .ops = {
>                 .add = acpi_battery_add,
>                 .remove = acpi_battery_remove,
> -               .notify = acpi_battery_notify,
>                 },
>         .drv.pm = &acpi_battery_pm,
>  };
> --
> 2.41.0
>