driver core: let dev_set_drvdata return int instead of void as it can fail

Before commit

	b402843 (Driver core: move dev_get/set_drvdata to drivers/base/dd.c)

calling dev_set_drvdata with dev=NULL was an unchecked error. After some
discussion about what to return in this case removing the check (and so
producing a null pointer exception) seems fine.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/base/dd.c

@@ -413,17 +413,16 @@ void *dev_get_drvdata(const struct device *dev)
 }
 EXPORT_SYMBOL(dev_get_drvdata);
 
-void dev_set_drvdata(struct device *dev, void *data)
+int dev_set_drvdata(struct device *dev, void *data)
 {
 	int error;
 
-	if (!dev)
-		return;
 	if (!dev->p) {
 		error = device_private_init(dev);
 		if (error)
-			return;
+			return error;
 	}
 	dev->p->driver_data = data;
+	return 0;
 }
 EXPORT_SYMBOL(dev_set_drvdata);

include/linux/device.h

@@ -557,7 +557,7 @@ extern int device_move(struct device *dev, struct device *new_parent,
 extern const char *device_get_devnode(struct device *dev,
 				      mode_t *mode, const char **tmp);
 extern void *dev_get_drvdata(const struct device *dev);
-extern void dev_set_drvdata(struct device *dev, void *data);
+extern int dev_set_drvdata(struct device *dev, void *data);
 
 /*
  * Root device objects for grouping under /sys/devices