linux-kernel - Re: [PATCH 1/2] devm-helpers: Add resource managed version of mutex init

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Date: Thu, 22 Feb 2024 23:42:11 +0200
From: andy.shevchenko@...il.com
To: Marek Behún <kabel@...nel.org>
Cc: linux-kernel@...r.kernel.org, Hans de Goede <hdegoede@...hat.com>,
	Matti Vaittinen <mazziesaccount@...il.com>,
	Linus Walleij <linus.walleij@...aro.org>,
	Bartosz Golaszewski <brgl@...ev.pl>,
	Lucas De Marchi <lucas.demarchi@...el.com>,
	Oded Gabbay <ogabbay@...nel.org>,
	Thomas Hellström <thomas.hellstrom@...ux.intel.com>,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Maxime Ripard <mripard@...nel.org>,
	Thomas Zimmermann <tzimmermann@...e.de>,
	David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>,
	Aleksandr Mezin <mezin.alexander@...il.com>,
	Jean Delvare <jdelvare@...e.com>,
	Guenter Roeck <linux@...ck-us.net>, Pavel Machek <pavel@....cz>,
	Lee Jones <lee@...nel.org>, Sebastian Reichel <sre@...nel.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	AngeloGioacchino Del Regno <angelogioacchino.delregno@...labora.com>,
	linux-gpio@...r.kernel.org, intel-xe@...ts.freedesktop.org,
	dri-devel@...ts.freedesktop.org, linux-hwmon@...r.kernel.org,
	linux-leds@...r.kernel.org, linux-pm@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	linux-mediatek@...ts.infradead.org,
	George Stark <gnstark@...utedevices.com>
Subject: Re: [PATCH 1/2] devm-helpers: Add resource managed version of mutex
 init

Thu, Feb 22, 2024 at 03:58:37PM +0100, Marek Behún kirjoitti:
> A few drivers are doing resource-managed mutex initialization by
> implementing ad-hoc one-liner mutex dropping functions and using them
> with devm_add_action_or_reset(). Help drivers avoid these repeated
> one-liners by adding managed version of mutex initialization.
> 
> Use the new function devm_mutex_init() in the following drivers:
>   drivers/gpio/gpio-pisosr.c
>   drivers/gpio/gpio-sim.c
>   drivers/gpu/drm/xe/xe_hwmon.c
>   drivers/hwmon/nzxt-smart2.c
>   drivers/leds/leds-is31fl319x.c
>   drivers/power/supply/mt6370-charger.c
>   drivers/power/supply/rt9467-charger.c

Pardon me, but why?

https://lore.kernel.org/linux-leds/20231214173614.2820929-1-gnstark@salutedevices.com/

Can you cooperate, folks, instead of doing something independently?


> --- a/include/linux/devm-helpers.h
> +++ b/include/linux/devm-helpers.h
> @@ -24,6 +24,8 @@
>   */
>  
>  #include <linux/device.h>
> +#include <linux/kconfig.h>
> +#include <linux/mutex.h>
>  #include <linux/workqueue.h>
>  
>  static inline void devm_delayed_work_drop(void *res)
> @@ -76,4 +78,34 @@ static inline int devm_work_autocancel(struct device *dev,
>  	return devm_add_action(dev, devm_work_drop, w);
>  }
>  
> +static inline void devm_mutex_drop(void *res)
> +{
> +	mutex_destroy(res);
> +}
> +
> +/**
> + * devm_mutex_init - Resource managed mutex initialization
> + * @dev:	Device which lifetime mutex is bound to
> + * @lock:	Mutex to be initialized (and automatically destroyed)
> + *
> + * Initialize mutex which is automatically destroyed when driver is detached.
> + * A few drivers initialize mutexes which they want destroyed before driver is
> + * detached, for debugging purposes.
> + * devm_mutex_init() can be used to omit the explicit mutex_destroy() call when
> + * driver is detached.
> + */
> +static inline int devm_mutex_init(struct device *dev, struct mutex *lock)
> +{
> +	mutex_init(lock);
> +
> +	/*
> +	 * mutex_destroy() is an empty function if CONFIG_DEBUG_MUTEXES is
> +	 * disabled. No need to allocate an action in that case.
> +	 */
> +	if (IS_ENABLED(CONFIG_DEBUG_MUTEXES))
> +		return devm_add_action_or_reset(dev, devm_mutex_drop, lock);
> +	else
> +		return 0;
> +}

Cc: George Stark <gnstark@...utedevices.com>

-- 
With Best Regards,
Andy Shevchenko