linux-kernel - Re: [PATCH v2 1/3] ACPI: battery: Simplify battery hook locking

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Message-ID: <5b3e4ec1-e5a6-cb77-1d57-3515eb051cc2@linux.intel.com>
Date: Mon, 23 Sep 2024 16:35:39 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Armin Wolf <W_Armin@....de>
cc: mjg59@...f.ucam.org, pali@...nel.org, dilinger@...ued.net, 
    "Rafael J. Wysocki" <rafael@...nel.org>, lenb@...nel.org, 
    Hans de Goede <hdegoede@...hat.com>, platform-driver-x86@...r.kernel.org, 
    linux-acpi@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/3] ACPI: battery: Simplify battery hook locking

On Sun, 22 Sep 2024, Armin Wolf wrote:

> Move the conditional locking from __battery_hook_unregister()
> into battery_hook_unregister() and rename the low-level function
> to simplify the locking during battery hook removal.
> 
> Signed-off-by: Armin Wolf <W_Armin@....de>

Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>

-- 
 i.

> ---
>  drivers/acpi/battery.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/acpi/battery.c b/drivers/acpi/battery.c
> index da3a879d638a..10e9136897a7 100644
> --- a/drivers/acpi/battery.c
> +++ b/drivers/acpi/battery.c
> @@ -706,28 +706,28 @@ static LIST_HEAD(acpi_battery_list);
>  static LIST_HEAD(battery_hook_list);
>  static DEFINE_MUTEX(hook_mutex);
> 
> -static void __battery_hook_unregister(struct acpi_battery_hook *hook, int lock)
> +static void battery_hook_unregister_unlocked(struct acpi_battery_hook *hook)
>  {
>  	struct acpi_battery *battery;
> +
>  	/*
>  	 * In order to remove a hook, we first need to
>  	 * de-register all the batteries that are registered.
>  	 */
> -	if (lock)
> -		mutex_lock(&hook_mutex);
>  	list_for_each_entry(battery, &acpi_battery_list, list) {
>  		if (!hook->remove_battery(battery->bat, hook))
>  			power_supply_changed(battery->bat);
>  	}
>  	list_del(&hook->list);
> -	if (lock)
> -		mutex_unlock(&hook_mutex);
> +
>  	pr_info("extension unregistered: %s\n", hook->name);
>  }
> 
>  void battery_hook_unregister(struct acpi_battery_hook *hook)
>  {
> -	__battery_hook_unregister(hook, 1);
> +	mutex_lock(&hook_mutex);
> +	battery_hook_unregister_unlocked(hook);
> +	mutex_unlock(&hook_mutex);
>  }
>  EXPORT_SYMBOL_GPL(battery_hook_unregister);
> 
> @@ -753,7 +753,7 @@ void battery_hook_register(struct acpi_battery_hook *hook)
>  			 * hooks.
>  			 */
>  			pr_err("extension failed to load: %s", hook->name);
> -			__battery_hook_unregister(hook, 0);
> +			battery_hook_unregister_unlocked(hook);
>  			goto end;
>  		}
> 
> @@ -807,7 +807,7 @@ static void battery_hook_add_battery(struct acpi_battery *battery)
>  			 */
>  			pr_err("error in extension, unloading: %s",
>  					hook_node->name);
> -			__battery_hook_unregister(hook_node, 0);
> +			battery_hook_unregister_unlocked(hook_node);
>  		}
>  	}
>  	mutex_unlock(&hook_mutex);
> @@ -840,7 +840,7 @@ static void __exit battery_hook_exit(void)
>  	 * need to remove the hooks.
>  	 */
>  	list_for_each_entry_safe(hook, ptr, &battery_hook_list, list) {
> -		__battery_hook_unregister(hook, 1);
> +		battery_hook_unregister(hook);
>  	}
>  	mutex_destroy(&hook_mutex);
>  }
> --
> 2.39.5
>