Fix up ACPI device breakage.

For some reason the ACPI people continue to make the mistake
of thinking that they are the root of the system.  Disabuse
them of that notion.

drivers/base/core.c

@@ -19,7 +19,10 @@
 # define DBG(x...)
 #endif
 
-static struct device * device_root = NULL;
+static struct device device_root = {
+	bus_id:		"root",
+	name:		"System root",
+};
 
 int (*platform_notify)(struct device * dev) = NULL;
 int (*platform_notify_remove)(struct device * dev) = NULL;
@@ -27,7 +30,7 @@ int (*platform_notify_remove)(struct device * dev) = NULL;
 extern int device_make_dir(struct device * dev);
 extern void device_remove_dir(struct device * dev);
 
-static spinlock_t device_lock;
+static spinlock_t device_lock = SPIN_LOCK_UNLOCKED;
 
 /**
  * device_register - register a device
@@ -35,10 +38,7 @@ static spinlock_t device_lock;
  *
  * First, make sure that the device has a parent, create
  * a directory for it, then add it to the parent's list of
- * children.  Note that the first device to be registered 
- * becomes the device_root, implying that the system root
- * driver (e.g. ACPI, PnP BIOS, etc.) begins the device
- * enumeration process.
+ * children.
  */
 int device_register(struct device *dev)
 {
@@ -47,28 +47,15 @@ int device_register(struct device *dev)
 	if (!dev || !strlen(dev->bus_id))
 		return -EINVAL;
 
-	/* perform first-time initialization (system root device) */
-	if (!device_root) {
-		spin_lock_init(&device_lock);
-
-		error = init_driverfs_fs();
-		if (error) {
-			panic("DEV: could not initialise driverfs\n");
-			return error;
-		}
-
-		device_root = dev;
-	}
-
 	spin_lock(&device_lock);
 	INIT_LIST_HEAD(&dev->node);
 	INIT_LIST_HEAD(&dev->children);
 	spin_lock_init(&dev->lock);
 	atomic_set(&dev->refcount,2);
 
-	if (dev != device_root) {
+	if (dev != &device_root) {
 		if (!dev->parent)
-			dev->parent = device_root;
+			dev->parent = &device_root;
 		get_device(dev->parent);
 		list_add_tail(&dev->node,&dev->parent->children);
 	}
@@ -134,32 +121,22 @@ void put_device(struct device * dev)
 
 static int __init device_init_root(void)
 {
-	int error = 0;
-
-	device_root = kmalloc(sizeof(struct device),GFP_KERNEL);
-	if (!device_root)
-		return -ENOMEM;
-	memset(device_root,0,sizeof(struct device));
-
-	if ((error = device_register(device_root)))
-		printk(KERN_ERR "%s: device root init failed!\n", __FUNCTION__);
-
-	return error;
+	return device_register(&device_root);
 }
 
-/**
- * device_init - initialize the root device
- *
- * Ensures creation of the system root device (device_root)
- * in the absence of a system root enumerator (e.g. ACPI,
- * PnP BIOS, <insert non-IA paradigm here>, etc.).
- */
 static int __init device_init(void)
 {
-	if (!device_root)
-		return device_init_root();
+	int error;
 
-	return 0;
+	error = init_driverfs_fs();
+	if (error) {
+		panic("DEV: could not initialize driverfs");
+		return error;
+	}
+	error = device_init_root();
+	if (error)
+		printk(KERN_ERR "%s: device root init failed!\n", __FUNCTION__);
+	return error;
 }
 
 subsys_initcall(device_init);