Re: [PATCH v3 3/3] Input: ads7846: Switch to devm initialization

[Marco Felsch <m.felsch@pengutronix.de>]

Hi Daniel,

sry for my late response.

On 20-05-07 08:20, Daniel Mack wrote:
> This simplies the code a lot and fixes some potential resource leaks in
> the error return paths.
> 
> Signed-off-by: Daniel Mack <daniel@zonque.org>
> ---
>  drivers/input/touchscreen/ads7846.c | 123 ++++++++++------------------
>  1 file changed, 45 insertions(+), 78 deletions(-)
> 
> diff --git a/drivers/input/touchscreen/ads7846.c b/drivers/input/touchscreen/ads7846.c
> index 4635e8867d10..1f496c4ca6ad 100644
> --- a/drivers/input/touchscreen/ads7846.c
> +++ b/drivers/input/touchscreen/ads7846.c
> @@ -98,10 +98,6 @@ struct ads7846 {
>  	struct spi_device	*spi;
>  	struct regulator	*reg;
>  
> -#if IS_ENABLED(CONFIG_HWMON)
> -	struct device		*hwmon;
> -#endif
> -
>  	u16			model;
>  	u16			vref_mv;
>  	u16			vref_delay_usecs;
> @@ -513,6 +509,8 @@ __ATTRIBUTE_GROUPS(ads7846_attr);
>  
>  static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
>  {
> +	struct device *hwmon;
> +
>  	/* hwmon sensors need a reference voltage */
>  	switch (ts->model) {
>  	case 7846:
> @@ -533,17 +531,11 @@ static int ads784x_hwmon_register(struct spi_device *spi, struct ads7846 *ts)
>  		break;
>  	}
>  
> -	ts->hwmon = hwmon_device_register_with_groups(&spi->dev, spi->modalias,
> -						      ts, ads7846_attr_groups);
> -
> -	return PTR_ERR_OR_ZERO(ts->hwmon);
> -}
> +	hwmon = devm_hwmon_device_register_with_groups(&spi->dev,
> +						       spi->modalias, ts,
> +						       ads7846_attr_groups);
>  
> -static void ads784x_hwmon_unregister(struct spi_device *spi,
> -				     struct ads7846 *ts)
> -{
> -	if (ts->hwmon)
> -		hwmon_device_unregister(ts->hwmon);
> +	return PTR_ERR_OR_ZERO(hwmon);
>  }
>  
>  #else
> @@ -552,11 +544,6 @@ static inline int ads784x_hwmon_register(struct spi_device *spi,
>  {
>  	return 0;
>  }
> -
> -static inline void ads784x_hwmon_unregister(struct spi_device *spi,
> -					    struct ads7846 *ts)
> -{
> -}
>  #endif
>  
>  static ssize_t ads7846_pen_down_show(struct device *dev,
> @@ -949,8 +936,8 @@ static int ads7846_setup_pendown(struct spi_device *spi,
>  		ts->get_pendown_state = pdata->get_pendown_state;
>  	} else if (gpio_is_valid(pdata->gpio_pendown)) {
>  
> -		err = gpio_request_one(pdata->gpio_pendown, GPIOF_IN,
> -				       "ads7846_pendown");
> +		err = devm_gpio_request_one(&spi->dev, pdata->gpio_pendown,
> +					    GPIOF_IN, "ads7846_pendown");
>  		if (err) {
>  			dev_err(&spi->dev,
>  				"failed to request/setup pendown GPIO%d: %d\n",
> @@ -1266,6 +1253,11 @@ static const struct ads7846_platform_data *ads7846_probe_dt(struct device *dev)
>  }
>  #endif
>  
> +static void ads7846_regulator_disable(void *regulator)
> +{
> +	regulator_disable(regulator);
> +}
> +
>  static int ads7846_probe(struct spi_device *spi)
>  {
>  	const struct ads7846_platform_data *pdata;
> @@ -1299,13 +1291,17 @@ static int ads7846_probe(struct spi_device *spi)
>  	if (err < 0)
>  		return err;
>  
> -	ts = kzalloc(sizeof(struct ads7846), GFP_KERNEL);
> -	packet = kzalloc(sizeof(struct ads7846_packet), GFP_KERNEL);
> -	input_dev = input_allocate_device();
> -	if (!ts || !packet || !input_dev) {
> -		err = -ENOMEM;
> -		goto err_free_mem;
> -	}
> +	ts = devm_kzalloc(dev, sizeof(struct ads7846), GFP_KERNEL);
> +	if (!ts)
> +		return -ENOMEM;
> +
> +	packet = devm_kzalloc(dev, sizeof(struct ads7846_packet), GFP_KERNEL);
> +	if (!packet)
> +		return -ENOMEM;
> +
> +	input_dev = devm_input_allocate_device(dev);
> +	if (!input_dev)
> +		return -ENOMEM;
>  
>  	spi_set_drvdata(spi, ts);
>  
> @@ -1319,10 +1315,8 @@ static int ads7846_probe(struct spi_device *spi)
>  	pdata = dev_get_platdata(dev);
>  	if (!pdata) {
>  		pdata = ads7846_probe_dt(dev);
> -		if (IS_ERR(pdata)) {
> -			err = PTR_ERR(pdata);
> -			goto err_free_mem;
> -		}
> +		if (IS_ERR(pdata))
> +			return PTR_ERR(pdata);
>  	}
>  
>  	ts->model = pdata->model ? : 7846;
> @@ -1344,7 +1338,7 @@ static int ads7846_probe(struct spi_device *spi)
>  
>  	err = ads7846_setup_pendown(spi, ts, pdata);
>  	if (err)
> -		goto err_free_mem;
> +		return err;
>  
>  	if (pdata->penirq_recheck_delay_usecs)
>  		ts->penirq_recheck_delay_usecs =
> @@ -1391,41 +1385,47 @@ static int ads7846_probe(struct spi_device *spi)
>  
>  	ads7846_setup_spi_msg(ts, pdata);
>  
> -	ts->reg = regulator_get(dev, "vcc");
> +	ts->reg = devm_regulator_get(dev, "vcc");
>  	if (IS_ERR(ts->reg)) {
>  		err = PTR_ERR(ts->reg);
>  		dev_err(dev, "unable to get regulator: %d\n", err);
> -		goto err_free_gpio;
> +		return err;
>  	}
>  
>  	err = regulator_enable(ts->reg);
>  	if (err) {
>  		dev_err(dev, "unable to enable regulator: %d\n", err);
> -		goto err_put_regulator;
> +		return err;
>  	}
>  
> +	err = devm_add_action_or_reset(dev, ads7846_regulator_disable, ts->reg);
> +	if (err)
> +		return err;
> +
>  	irq_flags = pdata->irq_flags ? : IRQF_TRIGGER_FALLING;
>  	irq_flags |= IRQF_ONESHOT;
>  
> -	err = request_threaded_irq(spi->irq, ads7846_hard_irq, ads7846_irq,
> -				   irq_flags, dev->driver->name, ts);
> +	err = devm_request_threaded_irq(dev, spi->irq,
> +					ads7846_hard_irq, ads7846_irq,
> +					irq_flags, dev->driver->name, ts);
>  	if (err && !pdata->irq_flags) {
>  		dev_info(dev,
>  			"trying pin change workaround on irq %d\n", spi->irq);
>  		irq_flags |= IRQF_TRIGGER_RISING;
> -		err = request_threaded_irq(spi->irq,
> -				  ads7846_hard_irq, ads7846_irq,
> -				  irq_flags, dev->driver->name, ts);
> +		err = devm_request_threaded_irq(dev, spi->irq,
> +						ads7846_hard_irq, ads7846_irq,
> +						irq_flags, dev->driver->name,
> +						ts);
>  	}
>  
>  	if (err) {
>  		dev_dbg(dev, "irq %d busy?\n", spi->irq);
> -		goto err_disable_regulator;
> +		return err;
>  	}
>  
>  	err = ads784x_hwmon_register(spi, ts);
>  	if (err)
> -		goto err_free_irq;
> +		return err;
>  
>  	dev_info(dev, "touchscreen, irq %d\n", spi->irq);
>  
> @@ -1440,7 +1440,7 @@ static int ads7846_probe(struct spi_device *spi)
>  
>  	err = sysfs_create_group(&dev->kobj, &ads784x_attr_group);
>  	if (err)
> -		goto err_remove_hwmon;
> +		return err;
>  
>  	err = input_register_device(input_dev);
>  	if (err)
> @@ -1459,21 +1459,7 @@ static int ads7846_probe(struct spi_device *spi)
>  
>   err_remove_attr_group:
>  	sysfs_remove_group(&dev->kobj, &ads784x_attr_group);
> - err_remove_hwmon:
> -	ads784x_hwmon_unregister(spi, ts);
> - err_free_irq:
> -	free_irq(spi->irq, ts);
> - err_disable_regulator:
> -	regulator_disable(ts->reg);
> - err_put_regulator:
> -	regulator_put(ts->reg);
> - err_free_gpio:
> -	if (!ts->get_pendown_state)
> -		gpio_free(ts->gpio_pendown);
> - err_free_mem:
> -	input_free_device(input_dev);
> -	kfree(packet);
> -	kfree(ts);
> +
>  	return err;
>  }
>  
> @@ -1482,26 +1468,7 @@ static int ads7846_remove(struct spi_device *spi)
>  	struct ads7846 *ts = spi_get_drvdata(spi);
>  
>  	sysfs_remove_group(&spi->dev.kobj, &ads784x_attr_group);
> -
>  	ads7846_disable(ts);

Did you tested the bind/unbind path? I think we are getting troubles
here because ads7846_disable calls ads7846_stop() and
regulator_disable(). Since we are using the devm_action the regualtor
gets disabled by this action and ads7846_disable(). This causes a
refcount problem.

Regards,
  Marco

> -	free_irq(ts->spi->irq, ts);
> -
> -	input_unregister_device(ts->input);
> -
> -	ads784x_hwmon_unregister(spi, ts);
> -
> -	regulator_put(ts->reg);
> -
> -	if (!ts->get_pendown_state) {
> -		/*
> -		 * If we are not using specialized pendown method we must
> -		 * have been relying on gpio we set up ourselves.
> -		 */
> -		gpio_free(ts->gpio_pendown);
> -	}
> -
> -	kfree(ts->packet);
> -	kfree(ts);
>  
>  	dev_dbg(&spi->dev, "unregistered touchscreen\n");
>  
> -- 
> 2.26.2
> 
>