[PATCH] hwmon: Fix WARN_ON() always called from devm_hwmon_device_unregister()

[Matthew Sanders]

devm_hwmon_device_unregister() only takes parent of a devres-managed
hwmon device as an argument. This always fails, as devres can't find
the hwmon device it needs to unregister with the parent device alone.
Without this patch, the WARN_ON() in devm_hwmon_device_unregister() will
always be displayed unconditionally:

[    7.969746] WARNING: CPU: 1 PID: 224 at drivers/hwmon/hwmon.c:1205 devm_hwmon_device_unregister+0x28/0x30

This patch adds an extra argument to devm_hwmon_device_unregister(), a
pointer to a hwmon device which was previously registered to the
parent using devres.

There aren't any drivers which currently make use of this function, so
any existing users of devm_hwmon_* shouldn't require any changes as a
result of this patch.
---
 drivers/hwmon/hwmon.c | 6 ++++--
 include/linux/hwmon.h | 2 +-
 2 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index a362080d41fa..84945a276320 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -1199,10 +1199,12 @@ static int devm_hwmon_match(struct device *dev, void *res, void *data)
  * devm_hwmon_device_unregister - removes a previously registered hwmon device
  *
  * @dev: the parent device of the device to unregister
+ * @hwdev: the hwmon device to unregister
  */
-void devm_hwmon_device_unregister(struct device *dev)
+void devm_hwmon_device_unregister(struct device *dev, struct device *hwdev)
 {
-	WARN_ON(devres_release(dev, devm_hwmon_release, devm_hwmon_match, dev));
+	WARN_ON(devres_release(dev, devm_hwmon_release, devm_hwmon_match,
+			       hwdev));
 }
 EXPORT_SYMBOL_GPL(devm_hwmon_device_unregister);
 
diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
index e94314760aab..2434c6fc17a7 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -481,7 +481,7 @@ devm_hwmon_device_register_with_info(struct device *dev,
 				const struct attribute_group **extra_groups);
 
 void hwmon_device_unregister(struct device *dev);
-void devm_hwmon_device_unregister(struct device *dev);
+void devm_hwmon_device_unregister(struct device *dev, struct device *hwdev);
 
 int hwmon_notify_event(struct device *dev, enum hwmon_sensor_types type,
 		       u32 attr, int channel);
-- 
2.46.0