fbdev: fix race in device_create

There is a race from when a device is created with device_create() and
then the drvdata is set with a call to dev_set_drvdata() in which a
sysfs file could be open, yet the drvdata will be NULL, causing all
sorts of bad things to happen.

This patch fixes the problem by using the new function,
device_create_drvdata().

Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/video/display/display-sysfs.c

@@ -26,6 +26,7 @@
 #include <linux/ctype.h>
 #include <linux/idr.h>
 #include <linux/err.h>
+#include <linux/kdev_t.h>
 
 static ssize_t display_show_name(struct device *dev,
 				struct device_attribute *attr, char *buf)
@@ -152,10 +153,13 @@ struct display_device *display_device_register(struct display_driver *driver,
 		mutex_unlock(&allocated_dsp_lock);
 
 		if (!ret) {
-			new_dev->dev = device_create(display_class, parent, 0,
-						"display%d", new_dev->idx);
+			new_dev->dev = device_create_drvdata(display_class,
+							     parent,
+							     MKDEV(0,0),
+							     new_dev,
+							     "display%d",
+							     new_dev->idx);
 			if (!IS_ERR(new_dev->dev)) {
-				dev_set_drvdata(new_dev->dev, new_dev);
 				new_dev->parent = parent;
 				new_dev->driver = driver;
 				mutex_init(&new_dev->lock);