[6/6] hwmon: (pwm-fan) Use devm_thermal_of_cooling_device_register
diff mbox series

Message ID 1555617500-10862-7-git-send-email-linux@roeck-us.net
State Accepted
Delegated to: Eduardo Valentin
Headers show
Series
  • thermal: Introduce devm_thermal_of_cooling_device_register
Related show

Commit Message

Guenter Roeck April 18, 2019, 7:58 p.m. UTC
Use devm_thermal_of_cooling_device_register() to register the cooling
device. Also use devm_add_action_or_reset() to stop the fan on device
removal, and to disable the pwm. Introduce a local 'dev' variable in
the probe function to make the code easier to read.

As a side effect, this fixes a bug seen if pwm_fan_of_get_cooling_data()
returned an error. In that situation, the pwm was not disabled, and
the fan was not stopped. Using devm functions also ensures that the
pwm is disabled and that the fan is stopped only after the hwmon device
has been unregistered.

Cc: Lukasz Majewski <l.majewski@samsung.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/pwm-fan.c | 73 ++++++++++++++++++++-----------------------------
 1 file changed, 29 insertions(+), 44 deletions(-)

Comments

Marek Szyprowski May 20, 2019, 3:21 p.m. UTC | #1
Dear All,

On 2019-04-18 21:58, Guenter Roeck wrote:
> Use devm_thermal_of_cooling_device_register() to register the cooling
> device. Also use devm_add_action_or_reset() to stop the fan on device
> removal, and to disable the pwm. Introduce a local 'dev' variable in
> the probe function to make the code easier to read.
>
> As a side effect, this fixes a bug seen if pwm_fan_of_get_cooling_data()
> returned an error. In that situation, the pwm was not disabled, and
> the fan was not stopped. Using devm functions also ensures that the
> pwm is disabled and that the fan is stopped only after the hwmon device
> has been unregistered.
>
> Cc: Lukasz Majewski <l.majewski@samsung.com>
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>


I've noticed the following lockdep warning after this commit during CPU 
hotplug tests on TM2e board (ARM64 Exynos5433). It looks like a false 
positive, but it would be nice to annotate it somehow in the code to 
make lockdep happy:

--->8---

IRQ 8: no longer affine to CPU5
CPU5: shutdown
IRQ 9: no longer affine to CPU6
CPU6: shutdown

======================================================
WARNING: possible circular locking dependency detected
5.2.0-rc1+ #6093 Not tainted
------------------------------------------------------
cpuhp/7/43 is trying to acquire lock:
00000000d1a60be3 (thermal_list_lock){+.+.}, at: 
thermal_cooling_device_unregister+0x34/0x1c0

but task is already holding lock:
00000000a6a56c92 (&policy->rwsem){++++}, at: cpufreq_offline+0x68/0x228

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3 (&policy->rwsem){++++}:
        down_write+0x48/0x98
        cpufreq_cpu_acquire+0x20/0x58
        cpufreq_update_policy+0x28/0xc0
        cpufreq_set_cur_state+0x44/0x70
        thermal_cdev_update+0x7c/0x240
        step_wise_throttle+0x4c/0x88
        handle_thermal_trip+0xc0/0x348
        thermal_zone_device_update.part.7+0x6c/0x250
        thermal_zone_device_update+0x28/0x38
        exynos_tmu_work+0x28/0x70
        process_one_work+0x298/0x6c0
        worker_thread+0x48/0x430
        kthread+0x100/0x130
        ret_from_fork+0x10/0x18

-> #2 (&cdev->lock){+.+.}:
        __mutex_lock+0x90/0x890
        mutex_lock_nested+0x1c/0x28
        thermal_zone_bind_cooling_device+0x2cc/0x3e0
        of_thermal_bind+0x9c/0xf8
        __thermal_cooling_device_register+0x1a4/0x388
        thermal_of_cooling_device_register+0xc/0x18
        __cpufreq_cooling_register+0x360/0x410
        of_cpufreq_cooling_register+0x84/0xf8
        cpufreq_online+0x414/0x720
        cpufreq_add_dev+0x78/0x88
        subsys_interface_register+0xa4/0xf8
        cpufreq_register_driver+0x140/0x1e0
        dt_cpufreq_probe+0xb0/0x130
        platform_drv_probe+0x50/0xa8
        really_probe+0x1b0/0x2a0
        driver_probe_device+0x58/0x100
        __device_attach_driver+0x90/0xc0
        bus_for_each_drv+0x70/0xc8
        __device_attach+0xdc/0x140
        device_initial_probe+0x10/0x18
        bus_probe_device+0x94/0xa0
        device_add+0x39c/0x5c8
        platform_device_add+0x110/0x248
        platform_device_register_full+0x134/0x178
        cpufreq_dt_platdev_init+0x114/0x14c
        do_one_initcall+0x84/0x430
        kernel_init_freeable+0x440/0x534
        kernel_init+0x10/0x108
        ret_from_fork+0x10/0x18

-> #1 (&tz->lock){+.+.}:
        __mutex_lock+0x90/0x890
        mutex_lock_nested+0x1c/0x28
        thermal_zone_bind_cooling_device+0x2b8/0x3e0
        of_thermal_bind+0x9c/0xf8
        __thermal_cooling_device_register+0x1a4/0x388
        thermal_of_cooling_device_register+0xc/0x18
        __cpufreq_cooling_register+0x360/0x410
        of_cpufreq_cooling_register+0x84/0xf8
        cpufreq_online+0x414/0x720
        cpufreq_add_dev+0x78/0x88
        subsys_interface_register+0xa4/0xf8
        cpufreq_register_driver+0x140/0x1e0
        dt_cpufreq_probe+0xb0/0x130
        platform_drv_probe+0x50/0xa8
        really_probe+0x1b0/0x2a0
        driver_probe_device+0x58/0x100
        __device_attach_driver+0x90/0xc0
        bus_for_each_drv+0x70/0xc8
        __device_attach+0xdc/0x140
        device_initial_probe+0x10/0x18
        bus_probe_device+0x94/0xa0
        device_add+0x39c/0x5c8
        platform_device_add+0x110/0x248
        platform_device_register_full+0x134/0x178
        cpufreq_dt_platdev_init+0x114/0x14c
        do_one_initcall+0x84/0x430
        kernel_init_freeable+0x440/0x534
        kernel_init+0x10/0x108
        ret_from_fork+0x10/0x18

-> #0 (thermal_list_lock){+.+.}:
        lock_acquire+0xdc/0x260
        __mutex_lock+0x90/0x890
        mutex_lock_nested+0x1c/0x28
        thermal_cooling_device_unregister+0x34/0x1c0
        cpufreq_cooling_unregister+0x78/0xd0
        cpufreq_offline+0x200/0x228
        cpuhp_cpufreq_offline+0xc/0x18
        cpuhp_invoke_callback+0xd0/0xcb0
        cpuhp_thread_fun+0x1e8/0x258
        smpboot_thread_fn+0x1b4/0x2d0
        kthread+0x100/0x130
        ret_from_fork+0x10/0x18

other info that might help us debug this:

Chain exists of:
   thermal_list_lock --> &cdev->lock --> &policy->rwsem

  Possible unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
   lock(&policy->rwsem);
                                lock(&cdev->lock);
                                lock(&policy->rwsem);
   lock(thermal_list_lock);

  *** DEADLOCK ***

3 locks held by cpuhp/7/43:
  #0: 00000000ae30cc2b (cpu_hotplug_lock.rw_sem){++++}, at: 
cpuhp_thread_fun+0x34/0x258
  #1: 00000000a0e2460a (cpuhp_state-down){+.+.}, at: 
cpuhp_thread_fun+0x178/0x258
  #2: 00000000a6a56c92 (&policy->rwsem){++++}, at: 
cpufreq_offline+0x68/0x228

stack backtrace:
CPU: 7 PID: 43 Comm: cpuhp/7 Not tainted 5.2.0-rc1+ #6093
Hardware name: Samsung TM2E board (DT)
Call trace:
  dump_backtrace+0x0/0x158
  show_stack+0x14/0x20
  dump_stack+0xc8/0x114
  print_circular_bug+0x1cc/0x2d8
  __lock_acquire+0x18f4/0x20f8
  lock_acquire+0xdc/0x260
  __mutex_lock+0x90/0x890
  mutex_lock_nested+0x1c/0x28
  thermal_cooling_device_unregister+0x34/0x1c0
  cpufreq_cooling_unregister+0x78/0xd0
  cpufreq_offline+0x200/0x228
  cpuhp_cpufreq_offline+0xc/0x18
  cpuhp_invoke_callback+0xd0/0xcb0
  cpuhp_thread_fun+0x1e8/0x258
  smpboot_thread_fn+0x1b4/0x2d0
  kthread+0x100/0x130
  ret_from_fork+0x10/0x18
IRQ 10: no longer affine to CPU7

--->8---

> ---
>   drivers/hwmon/pwm-fan.c | 73 ++++++++++++++++++++-----------------------------
>   1 file changed, 29 insertions(+), 44 deletions(-)
>
> diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
> index 167221c7628a..0243ba70107e 100644
> --- a/drivers/hwmon/pwm-fan.c
> +++ b/drivers/hwmon/pwm-fan.c
> @@ -207,33 +207,44 @@ static int pwm_fan_of_get_cooling_data(struct device *dev,
>   	return 0;
>   }
>   
> +static void pwm_fan_regulator_disable(void *data)
> +{
> +	regulator_disable(data);
> +}
> +
> +static void pwm_fan_pwm_disable(void *data)
> +{
> +	pwm_disable(data);
> +}
> +
>   static int pwm_fan_probe(struct platform_device *pdev)
>   {
>   	struct thermal_cooling_device *cdev;
> +	struct device *dev = &pdev->dev;
>   	struct pwm_fan_ctx *ctx;
>   	struct device *hwmon;
>   	int ret;
>   	struct pwm_state state = { };
>   
> -	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
> +	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
>   	if (!ctx)
>   		return -ENOMEM;
>   
>   	mutex_init(&ctx->lock);
>   
> -	ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL);
> +	ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
>   	if (IS_ERR(ctx->pwm)) {
>   		ret = PTR_ERR(ctx->pwm);
>   
>   		if (ret != -EPROBE_DEFER)
> -			dev_err(&pdev->dev, "Could not get PWM: %d\n", ret);
> +			dev_err(dev, "Could not get PWM: %d\n", ret);
>   
>   		return ret;
>   	}
>   
>   	platform_set_drvdata(pdev, ctx);
>   
> -	ctx->reg_en = devm_regulator_get_optional(&pdev->dev, "fan");
> +	ctx->reg_en = devm_regulator_get_optional(dev, "fan");
>   	if (IS_ERR(ctx->reg_en)) {
>   		if (PTR_ERR(ctx->reg_en) != -ENODEV)
>   			return PTR_ERR(ctx->reg_en);
> @@ -242,10 +253,11 @@ static int pwm_fan_probe(struct platform_device *pdev)
>   	} else {
>   		ret = regulator_enable(ctx->reg_en);
>   		if (ret) {
> -			dev_err(&pdev->dev,
> -				"Failed to enable fan supply: %d\n", ret);
> +			dev_err(dev, "Failed to enable fan supply: %d\n", ret);
>   			return ret;
>   		}
> +		devm_add_action_or_reset(dev, pwm_fan_regulator_disable,
> +					 ctx->reg_en);
>   	}
>   
>   	ctx->pwm_value = MAX_PWM;
> @@ -257,62 +269,36 @@ static int pwm_fan_probe(struct platform_device *pdev)
>   
>   	ret = pwm_apply_state(ctx->pwm, &state);
>   	if (ret) {
> -		dev_err(&pdev->dev, "Failed to configure PWM\n");
> -		goto err_reg_disable;
> +		dev_err(dev, "Failed to configure PWM\n");
> +		return ret;
>   	}
> +	devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx->pwm);
>   
> -	hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
> +	hwmon = devm_hwmon_device_register_with_groups(dev, "pwmfan",
>   						       ctx, pwm_fan_groups);
>   	if (IS_ERR(hwmon)) {
> -		dev_err(&pdev->dev, "Failed to register hwmon device\n");
> -		ret = PTR_ERR(hwmon);
> -		goto err_pwm_disable;
> +		dev_err(dev, "Failed to register hwmon device\n");
> +		return PTR_ERR(hwmon);
>   	}
>   
> -	ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
> +	ret = pwm_fan_of_get_cooling_data(dev, ctx);
>   	if (ret)
>   		return ret;
>   
>   	ctx->pwm_fan_state = ctx->pwm_fan_max_state;
>   	if (IS_ENABLED(CONFIG_THERMAL)) {
> -		cdev = thermal_of_cooling_device_register(pdev->dev.of_node,
> -							  "pwm-fan", ctx,
> -							  &pwm_fan_cooling_ops);
> +		cdev = devm_thermal_of_cooling_device_register(dev,
> +			dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
>   		if (IS_ERR(cdev)) {
> -			dev_err(&pdev->dev,
> +			dev_err(dev,
>   				"Failed to register pwm-fan as cooling device");
> -			ret = PTR_ERR(cdev);
> -			goto err_pwm_disable;
> +			return PTR_ERR(cdev);
>   		}
>   		ctx->cdev = cdev;
>   		thermal_cdev_update(cdev);
>   	}
>   
>   	return 0;
> -
> -err_pwm_disable:
> -	state.enabled = false;
> -	pwm_apply_state(ctx->pwm, &state);
> -
> -err_reg_disable:
> -	if (ctx->reg_en)
> -		regulator_disable(ctx->reg_en);
> -
> -	return ret;
> -}
> -
> -static int pwm_fan_remove(struct platform_device *pdev)
> -{
> -	struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
> -
> -	thermal_cooling_device_unregister(ctx->cdev);
> -	if (ctx->pwm_value)
> -		pwm_disable(ctx->pwm);
> -
> -	if (ctx->reg_en)
> -		regulator_disable(ctx->reg_en);
> -
> -	return 0;
>   }
>   
>   #ifdef CONFIG_PM_SLEEP
> @@ -380,7 +366,6 @@ MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
>   
>   static struct platform_driver pwm_fan_driver = {
>   	.probe		= pwm_fan_probe,
> -	.remove		= pwm_fan_remove,
>   	.driver	= {
>   		.name		= "pwm-fan",
>   		.pm		= &pwm_fan_pm,

Best regards

Patch
diff mbox series

diff --git a/drivers/hwmon/pwm-fan.c b/drivers/hwmon/pwm-fan.c
index 167221c7628a..0243ba70107e 100644
--- a/drivers/hwmon/pwm-fan.c
+++ b/drivers/hwmon/pwm-fan.c
@@ -207,33 +207,44 @@  static int pwm_fan_of_get_cooling_data(struct device *dev,
 	return 0;
 }
 
+static void pwm_fan_regulator_disable(void *data)
+{
+	regulator_disable(data);
+}
+
+static void pwm_fan_pwm_disable(void *data)
+{
+	pwm_disable(data);
+}
+
 static int pwm_fan_probe(struct platform_device *pdev)
 {
 	struct thermal_cooling_device *cdev;
+	struct device *dev = &pdev->dev;
 	struct pwm_fan_ctx *ctx;
 	struct device *hwmon;
 	int ret;
 	struct pwm_state state = { };
 
-	ctx = devm_kzalloc(&pdev->dev, sizeof(*ctx), GFP_KERNEL);
+	ctx = devm_kzalloc(dev, sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
 		return -ENOMEM;
 
 	mutex_init(&ctx->lock);
 
-	ctx->pwm = devm_of_pwm_get(&pdev->dev, pdev->dev.of_node, NULL);
+	ctx->pwm = devm_of_pwm_get(dev, dev->of_node, NULL);
 	if (IS_ERR(ctx->pwm)) {
 		ret = PTR_ERR(ctx->pwm);
 
 		if (ret != -EPROBE_DEFER)
-			dev_err(&pdev->dev, "Could not get PWM: %d\n", ret);
+			dev_err(dev, "Could not get PWM: %d\n", ret);
 
 		return ret;
 	}
 
 	platform_set_drvdata(pdev, ctx);
 
-	ctx->reg_en = devm_regulator_get_optional(&pdev->dev, "fan");
+	ctx->reg_en = devm_regulator_get_optional(dev, "fan");
 	if (IS_ERR(ctx->reg_en)) {
 		if (PTR_ERR(ctx->reg_en) != -ENODEV)
 			return PTR_ERR(ctx->reg_en);
@@ -242,10 +253,11 @@  static int pwm_fan_probe(struct platform_device *pdev)
 	} else {
 		ret = regulator_enable(ctx->reg_en);
 		if (ret) {
-			dev_err(&pdev->dev,
-				"Failed to enable fan supply: %d\n", ret);
+			dev_err(dev, "Failed to enable fan supply: %d\n", ret);
 			return ret;
 		}
+		devm_add_action_or_reset(dev, pwm_fan_regulator_disable,
+					 ctx->reg_en);
 	}
 
 	ctx->pwm_value = MAX_PWM;
@@ -257,62 +269,36 @@  static int pwm_fan_probe(struct platform_device *pdev)
 
 	ret = pwm_apply_state(ctx->pwm, &state);
 	if (ret) {
-		dev_err(&pdev->dev, "Failed to configure PWM\n");
-		goto err_reg_disable;
+		dev_err(dev, "Failed to configure PWM\n");
+		return ret;
 	}
+	devm_add_action_or_reset(dev, pwm_fan_pwm_disable, ctx->pwm);
 
-	hwmon = devm_hwmon_device_register_with_groups(&pdev->dev, "pwmfan",
+	hwmon = devm_hwmon_device_register_with_groups(dev, "pwmfan",
 						       ctx, pwm_fan_groups);
 	if (IS_ERR(hwmon)) {
-		dev_err(&pdev->dev, "Failed to register hwmon device\n");
-		ret = PTR_ERR(hwmon);
-		goto err_pwm_disable;
+		dev_err(dev, "Failed to register hwmon device\n");
+		return PTR_ERR(hwmon);
 	}
 
-	ret = pwm_fan_of_get_cooling_data(&pdev->dev, ctx);
+	ret = pwm_fan_of_get_cooling_data(dev, ctx);
 	if (ret)
 		return ret;
 
 	ctx->pwm_fan_state = ctx->pwm_fan_max_state;
 	if (IS_ENABLED(CONFIG_THERMAL)) {
-		cdev = thermal_of_cooling_device_register(pdev->dev.of_node,
-							  "pwm-fan", ctx,
-							  &pwm_fan_cooling_ops);
+		cdev = devm_thermal_of_cooling_device_register(dev,
+			dev->of_node, "pwm-fan", ctx, &pwm_fan_cooling_ops);
 		if (IS_ERR(cdev)) {
-			dev_err(&pdev->dev,
+			dev_err(dev,
 				"Failed to register pwm-fan as cooling device");
-			ret = PTR_ERR(cdev);
-			goto err_pwm_disable;
+			return PTR_ERR(cdev);
 		}
 		ctx->cdev = cdev;
 		thermal_cdev_update(cdev);
 	}
 
 	return 0;
-
-err_pwm_disable:
-	state.enabled = false;
-	pwm_apply_state(ctx->pwm, &state);
-
-err_reg_disable:
-	if (ctx->reg_en)
-		regulator_disable(ctx->reg_en);
-
-	return ret;
-}
-
-static int pwm_fan_remove(struct platform_device *pdev)
-{
-	struct pwm_fan_ctx *ctx = platform_get_drvdata(pdev);
-
-	thermal_cooling_device_unregister(ctx->cdev);
-	if (ctx->pwm_value)
-		pwm_disable(ctx->pwm);
-
-	if (ctx->reg_en)
-		regulator_disable(ctx->reg_en);
-
-	return 0;
 }
 
 #ifdef CONFIG_PM_SLEEP
@@ -380,7 +366,6 @@  MODULE_DEVICE_TABLE(of, of_pwm_fan_match);
 
 static struct platform_driver pwm_fan_driver = {
 	.probe		= pwm_fan_probe,
-	.remove		= pwm_fan_remove,
 	.driver	= {
 		.name		= "pwm-fan",
 		.pm		= &pwm_fan_pm,