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

[Matthew Auld <matthew.auld@intel.com>]

On 22/02/2024 14:58, Marek Behún wrote:
> 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
> 
> Signed-off-by: Marek Behún <kabel@kernel.org>
> ---
>   drivers/gpio/gpio-pisosr.c            |  9 ++-----
>   drivers/gpio/gpio-sim.c               | 12 ++--------
>   drivers/gpu/drm/xe/xe_hwmon.c         | 11 ++-------
>   drivers/hwmon/nzxt-smart2.c           |  9 ++-----
>   drivers/leds/leds-is31fl319x.c        |  9 ++-----
>   drivers/power/supply/mt6370-charger.c | 11 +--------
>   drivers/power/supply/rt9467-charger.c | 34 ++++-----------------------
>   include/linux/devm-helpers.h          | 32 +++++++++++++++++++++++++
>   8 files changed, 47 insertions(+), 80 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-pisosr.c b/drivers/gpio/gpio-pisosr.c
> index e3013e778e15..dddbf37e855f 100644
> --- a/drivers/gpio/gpio-pisosr.c
> +++ b/drivers/gpio/gpio-pisosr.c
> @@ -7,6 +7,7 @@
>   #include <linux/bitmap.h>
>   #include <linux/bitops.h>
>   #include <linux/delay.h>
> +#include <linux/devm-helpers.h>
>   #include <linux/gpio/consumer.h>
>   #include <linux/gpio/driver.h>
>   #include <linux/module.h>
> @@ -116,11 +117,6 @@ static const struct gpio_chip template_chip = {
>   	.can_sleep		= true,
>   };
>   
> -static void pisosr_mutex_destroy(void *lock)
> -{
> -	mutex_destroy(lock);
> -}
> -
>   static int pisosr_gpio_probe(struct spi_device *spi)
>   {
>   	struct device *dev = &spi->dev;
> @@ -147,8 +143,7 @@ static int pisosr_gpio_probe(struct spi_device *spi)
>   		return dev_err_probe(dev, PTR_ERR(gpio->load_gpio),
>   				     "Unable to allocate load GPIO\n");
>   
> -	mutex_init(&gpio->lock);
> -	ret = devm_add_action_or_reset(dev, pisosr_mutex_destroy, &gpio->lock);
> +	ret = devm_mutex_init(dev, &gpio->lock);
>   	if (ret)
>   		return ret;
>   
> diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
> index c4106e37e6db..fcfcaa4efe70 100644
> --- a/drivers/gpio/gpio-sim.c
> +++ b/drivers/gpio/gpio-sim.c
> @@ -12,6 +12,7 @@
>   #include <linux/completion.h>
>   #include <linux/configfs.h>
>   #include <linux/device.h>
> +#include <linux/devm-helpers.h>
>   #include <linux/err.h>
>   #include <linux/gpio/consumer.h>
>   #include <linux/gpio/driver.h>
> @@ -307,13 +308,6 @@ static ssize_t gpio_sim_sysfs_pull_store(struct device *dev,
>   	return len;
>   }
>   
> -static void gpio_sim_mutex_destroy(void *data)
> -{
> -	struct mutex *lock = data;
> -
> -	mutex_destroy(lock);
> -}
> -
>   static void gpio_sim_put_device(void *data)
>   {
>   	struct device *dev = data;
> @@ -457,9 +451,7 @@ static int gpio_sim_add_bank(struct fwnode_handle *swnode, struct device *dev)
>   	if (ret)
>   		return ret;
>   
> -	mutex_init(&chip->lock);
> -	ret = devm_add_action_or_reset(dev, gpio_sim_mutex_destroy,
> -				       &chip->lock);
> +	ret = devm_mutex_init(dev, &chip->lock);
>   	if (ret)
>   		return ret;
>   
> diff --git a/drivers/gpu/drm/xe/xe_hwmon.c b/drivers/gpu/drm/xe/xe_hwmon.c
> index 174ed2185481..bb88ae1c196c 100644
> --- a/drivers/gpu/drm/xe/xe_hwmon.c
> +++ b/drivers/gpu/drm/xe/xe_hwmon.c
> @@ -3,6 +3,7 @@
>    * Copyright © 2023 Intel Corporation
>    */
>   
> +#include <linux/devm-helpers.h>
>   #include <linux/hwmon-sysfs.h>
>   #include <linux/hwmon.h>
>   #include <linux/types.h>
> @@ -729,13 +730,6 @@ xe_hwmon_get_preregistration_info(struct xe_device *xe)
>   		xe_hwmon_energy_get(hwmon, &energy);
>   }
>   
> -static void xe_hwmon_mutex_destroy(void *arg)
> -{
> -	struct xe_hwmon *hwmon = arg;
> -
> -	mutex_destroy(&hwmon->hwmon_lock);
> -}
> -
>   void xe_hwmon_register(struct xe_device *xe)
>   {
>   	struct device *dev = xe->drm.dev;
> @@ -751,8 +745,7 @@ void xe_hwmon_register(struct xe_device *xe)
>   
>   	xe->hwmon = hwmon;
>   
> -	mutex_init(&hwmon->hwmon_lock);
> -	if (devm_add_action_or_reset(dev, xe_hwmon_mutex_destroy, hwmon))
> +	if (devm_mutex_init(dev, &hwmon->hwmon_lock))
>   		return;
>   
>   	/* primary GT to access device level properties */
> diff --git a/drivers/hwmon/nzxt-smart2.c b/drivers/hwmon/nzxt-smart2.c
> index 7aa586eb74be..00bc89607673 100644
> --- a/drivers/hwmon/nzxt-smart2.c
> +++ b/drivers/hwmon/nzxt-smart2.c
> @@ -5,6 +5,7 @@
>    * Copyright (c) 2021 Aleksandr Mezin
>    */
>   
> +#include <linux/devm-helpers.h>
>   #include <linux/hid.h>
>   #include <linux/hwmon.h>
>   #include <linux/math.h>
> @@ -721,11 +722,6 @@ static int __maybe_unused nzxt_smart2_hid_reset_resume(struct hid_device *hdev)
>   	return init_device(drvdata, drvdata->update_interval);
>   }
>   
> -static void mutex_fini(void *lock)
> -{
> -	mutex_destroy(lock);
> -}
> -
>   static int nzxt_smart2_hid_probe(struct hid_device *hdev,
>   				 const struct hid_device_id *id)
>   {
> @@ -741,8 +737,7 @@ static int nzxt_smart2_hid_probe(struct hid_device *hdev,
>   
>   	init_waitqueue_head(&drvdata->wq);
>   
> -	mutex_init(&drvdata->mutex);
> -	ret = devm_add_action_or_reset(&hdev->dev, mutex_fini, &drvdata->mutex);
> +	ret = devm_mutex_init(&hdev->dev, &drvdata->mutex);
>   	if (ret)
>   		return ret;
>   
> diff --git a/drivers/leds/leds-is31fl319x.c b/drivers/leds/leds-is31fl319x.c
> index 66c65741202e..e9d7cf6a386c 100644
> --- a/drivers/leds/leds-is31fl319x.c
> +++ b/drivers/leds/leds-is31fl319x.c
> @@ -8,6 +8,7 @@
>    * effect LEDs.
>    */
>   
> +#include <linux/devm-helpers.h>
>   #include <linux/err.h>
>   #include <linux/i2c.h>
>   #include <linux/leds.h>
> @@ -495,11 +496,6 @@ static inline int is31fl3196_db_to_gain(u32 dezibel)
>   	return dezibel / IS31FL3196_AUDIO_GAIN_DB_STEP;
>   }
>   
> -static void is31f1319x_mutex_destroy(void *lock)
> -{
> -	mutex_destroy(lock);
> -}
> -
>   static int is31fl319x_probe(struct i2c_client *client)
>   {
>   	struct is31fl319x_chip *is31;
> @@ -515,8 +511,7 @@ static int is31fl319x_probe(struct i2c_client *client)
>   	if (!is31)
>   		return -ENOMEM;
>   
> -	mutex_init(&is31->lock);
> -	err = devm_add_action_or_reset(dev, is31f1319x_mutex_destroy, &is31->lock);
> +	err = devm_mutex_init(dev, &is31->lock);
>   	if (err)
>   		return err;
>   
> diff --git a/drivers/power/supply/mt6370-charger.c b/drivers/power/supply/mt6370-charger.c
> index e24fce087d80..fa0517d0352d 100644
> --- a/drivers/power/supply/mt6370-charger.c
> +++ b/drivers/power/supply/mt6370-charger.c
> @@ -766,13 +766,6 @@ static int mt6370_chg_init_psy(struct mt6370_priv *priv)
>   	return PTR_ERR_OR_ZERO(priv->psy);
>   }
>   
> -static void mt6370_chg_destroy_attach_lock(void *data)
> -{
> -	struct mutex *attach_lock = data;
> -
> -	mutex_destroy(attach_lock);
> -}
> -
>   static void mt6370_chg_destroy_wq(void *data)
>   {
>   	struct workqueue_struct *wq = data;
> @@ -900,9 +893,7 @@ static int mt6370_chg_probe(struct platform_device *pdev)
>   	if (ret)
>   		return dev_err_probe(dev, ret, "Failed to init psy\n");
>   
> -	mutex_init(&priv->attach_lock);
> -	ret = devm_add_action_or_reset(dev, mt6370_chg_destroy_attach_lock,
> -				       &priv->attach_lock);
> +	ret = devm_mutex_init(dev, &priv->attach_lock);
>   	if (ret)
>   		return dev_err_probe(dev, ret, "Failed to init attach lock\n");
>   
> diff --git a/drivers/power/supply/rt9467-charger.c b/drivers/power/supply/rt9467-charger.c
> index fdfdc83ab045..84f07c22077f 100644
> --- a/drivers/power/supply/rt9467-charger.c
> +++ b/drivers/power/supply/rt9467-charger.c
> @@ -10,6 +10,7 @@
>   #include <linux/bitfield.h>
>   #include <linux/completion.h>
>   #include <linux/delay.h>
> +#include <linux/devm-helpers.h>
>   #include <linux/gpio/consumer.h>
>   #include <linux/i2c.h>
>   #include <linux/interrupt.h>
> @@ -1149,27 +1150,6 @@ static int rt9467_reset_chip(struct rt9467_chg_data *data)
>   	return regmap_field_write(data->rm_field[F_RST], 1);
>   }
>   
> -static void rt9467_chg_destroy_adc_lock(void *data)
> -{
> -	struct mutex *adc_lock = data;
> -
> -	mutex_destroy(adc_lock);
> -}
> -
> -static void rt9467_chg_destroy_attach_lock(void *data)
> -{
> -	struct mutex *attach_lock = data;
> -
> -	mutex_destroy(attach_lock);
> -}
> -
> -static void rt9467_chg_destroy_ichg_ieoc_lock(void *data)
> -{
> -	struct mutex *ichg_ieoc_lock = data;
> -
> -	mutex_destroy(ichg_ieoc_lock);
> -}
> -
>   static void rt9467_chg_complete_aicl_done(void *data)
>   {
>   	struct completion *aicl_done = data;
> @@ -1222,21 +1202,15 @@ static int rt9467_charger_probe(struct i2c_client *i2c)
>   	if (ret)
>   		return dev_err_probe(dev, ret, "Failed to add irq chip\n");
>   
> -	mutex_init(&data->adc_lock);
> -	ret = devm_add_action_or_reset(dev, rt9467_chg_destroy_adc_lock,
> -				       &data->adc_lock);
> +	ret = devm_mutex_init(dev, &data->adc_lock);
>   	if (ret)
>   		return dev_err_probe(dev, ret, "Failed to init ADC lock\n");
>   
> -	mutex_init(&data->attach_lock);
> -	ret = devm_add_action_or_reset(dev, rt9467_chg_destroy_attach_lock,
> -				       &data->attach_lock);
> +	ret = devm_mutex_init(dev, &data->attach_lock);
>   	if (ret)
>   		return dev_err_probe(dev, ret, "Failed to init attach lock\n");
>   
> -	mutex_init(&data->ichg_ieoc_lock);
> -	ret = devm_add_action_or_reset(dev, rt9467_chg_destroy_ichg_ieoc_lock,
> -				       &data->ichg_ieoc_lock);
> +	ret = devm_mutex_init(dev, &data->ichg_ieoc_lock);
>   	if (ret)
>   		return dev_err_probe(dev, ret, "Failed to init ICHG/IEOC lock\n");
>   
> diff --git a/include/linux/devm-helpers.h b/include/linux/devm-helpers.h
> index 74891802200d..70640fb96117 100644
> --- 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);

Do you know if this this needs __always_inline? The static lockdep key 
in mutex_init() should be different for each caller class. See 
c21f11d182c2 ("drm: fix drmm_mutex_init()").

> +
> +	/*
> +	 * 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;
> +}
> +
>   #endif