hwmon: Fix a potential race condition on unload

Fix a potential race condition when some hardware monitoring platform
drivers are being unloaded. I believe that the driver data pointer
shouldn't be cleared before all the sysfs files are removed, otherwise
a sysfs callback might attempt to dereference a NULL pointer. I'm not
sure exactly what the driver core protects drivers against, so let's
play it safe.

While we're here, clear the driver data pointer when probe fails, so
as to not leave an invalid pointer behind us.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>

drivers/hwmon/abituguru.c

@@ -1287,6 +1287,7 @@ static int __devinit abituguru_probe(struct platform_device *pdev)
 	for (i = 0; i < ARRAY_SIZE(abituguru_sysfs_attr); i++)
 		device_remove_file(&pdev->dev,
 			&abituguru_sysfs_attr[i].dev_attr);
+	platform_set_drvdata(pdev, NULL);
 	kfree(data);
 	return res;
 }
@@ -1296,13 +1297,13 @@ static int __devexit abituguru_remove(struct platform_device *pdev)
 	int i;
 	struct abituguru_data *data = platform_get_drvdata(pdev);
 
-	platform_set_drvdata(pdev, NULL);
 	hwmon_device_unregister(data->class_dev);
 	for (i = 0; data->sysfs_attr[i].dev_attr.attr.name; i++)
 		device_remove_file(&pdev->dev, &data->sysfs_attr[i].dev_attr);
 	for (i = 0; i < ARRAY_SIZE(abituguru_sysfs_attr); i++)
 		device_remove_file(&pdev->dev,
 			&abituguru_sysfs_attr[i].dev_attr);
+	platform_set_drvdata(pdev, NULL);
 	kfree(data);
 
 	return 0;

drivers/hwmon/f71805f.c

@@ -1242,12 +1242,12 @@ static int __devexit f71805f_remove(struct platform_device *pdev)
 	struct resource *res;
 	int i;
 
-	platform_set_drvdata(pdev, NULL);
 	hwmon_device_unregister(data->class_dev);
 	sysfs_remove_group(&pdev->dev.kobj, &f71805f_group);
 	for (i = 0; i < 4; i++)
 		sysfs_remove_group(&pdev->dev.kobj, &f71805f_group_optin[i]);
 	sysfs_remove_group(&pdev->dev.kobj, &f71805f_group_pwm_freq);
+	platform_set_drvdata(pdev, NULL);
 	kfree(data);
 
 	res = platform_get_resource(pdev, IORESOURCE_IO, 0);

drivers/hwmon/pc87427.c

@@ -484,14 +484,14 @@ static int __devexit pc87427_remove(struct platform_device *pdev)
 	struct resource *res;
 	int i;
 
-	platform_set_drvdata(pdev, NULL);
 	hwmon_device_unregister(data->class_dev);
 	device_remove_file(&pdev->dev, &dev_attr_name);
 	for (i = 0; i < 8; i++) {
 		if (!(data->fan_enabled & (1 << i)))
 			continue;
 		sysfs_remove_group(&pdev->dev.kobj, &pc87427_group_fan[i]);
 	}
+	platform_set_drvdata(pdev, NULL);
 	kfree(data);
 
 	res = platform_get_resource(pdev, IORESOURCE_IO, 0);

drivers/hwmon/smsc47m1.c

@@ -597,6 +597,7 @@ static int __devinit smsc47m1_probe(struct platform_device *pdev)
 error_remove_files:
 	sysfs_remove_group(&dev->kobj, &smsc47m1_group);
 error_free:
+	platform_set_drvdata(pdev, NULL);
 	kfree(data);
 error_release:
 	release_region(res->start, SMSC_EXTENT);
@@ -608,12 +609,12 @@ static int __devexit smsc47m1_remove(struct platform_device *pdev)
 	struct smsc47m1_data *data = platform_get_drvdata(pdev);
 	struct resource *res;
 
-	platform_set_drvdata(pdev, NULL);
 	hwmon_device_unregister(data->class_dev);
 	sysfs_remove_group(&pdev->dev.kobj, &smsc47m1_group);
 
 	res = platform_get_resource(pdev, IORESOURCE_IO, 0);
 	release_region(res->start, SMSC_EXTENT);
+	platform_set_drvdata(pdev, NULL);
 	kfree(data);
 
 	return 0;

drivers/hwmon/vt8231.c

@@ -743,6 +743,7 @@ int vt8231_probe(struct platform_device *pdev)
 	sysfs_remove_group(&pdev->dev.kobj, &vt8231_group);
 
 exit_free:
+	platform_set_drvdata(pdev, NULL);
 	kfree(data);
 
 exit_release:

drivers/hwmon/w83627hf.c

@@ -1306,6 +1306,7 @@ static int __devinit w83627hf_probe(struct platform_device *pdev)
 	sysfs_remove_group(&dev->kobj, &w83627hf_group);
 	sysfs_remove_group(&dev->kobj, &w83627hf_group_opt);
       ERROR3:
+	platform_set_drvdata(pdev, NULL);
 	kfree(data);
       ERROR1:
 	release_region(res->start, WINB_REGION_SIZE);
@@ -1318,11 +1319,11 @@ static int __devexit w83627hf_remove(struct platform_device *pdev)
 	struct w83627hf_data *data = platform_get_drvdata(pdev);
 	struct resource *res;
 
-	platform_set_drvdata(pdev, NULL);
 	hwmon_device_unregister(data->class_dev);
 
 	sysfs_remove_group(&pdev->dev.kobj, &w83627hf_group);
 	sysfs_remove_group(&pdev->dev.kobj, &w83627hf_group_opt);
+	platform_set_drvdata(pdev, NULL);
 	kfree(data);
 
 	res = platform_get_resource(pdev, IORESOURCE_IO, 0);