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>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/hwmon/smsc47m1.c b/drivers/hwmon/smsc47m1.c
index 9bac3c2d84f9..1de2f2be8708 100644
--- a/drivers/hwmon/smsc47m1.c
+++ b/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;