Driver Core: add warnings if .release functions are not set for objects.

This has been in the -mm tree for a while and has helped a lot in finding
lots of improper users of the driver core.  It also moves the driver core
code up quite a few levels on the "Rusty's guide to kernel APIs".

drivers/base/class.c

@@ -194,6 +194,12 @@ static void class_dev_release(struct kobject * kobj)
 
 	if (cls->release)
 		cls->release(cd);
+	else {
+		printk(KERN_ERR "Device class '%s' does not have a release() function, "
+			"it is broken and must be fixed.\n",
+			cd->class_id);
+		WARN_ON(1);
+	}
 }
 
 static struct kobj_type ktype_class_device = {

drivers/base/core.c

@@ -77,6 +77,12 @@ static void device_release(struct kobject * kobj)
 	struct device * dev = to_dev(kobj);
 	if (dev->release)
 		dev->release(dev);
+	else {
+		printk(KERN_ERR "Device '%s' does not have a release() function, "
+			"it is broken and must be fixed.\n",
+			dev->bus_id);
+		WARN_ON(1);
+	}
 }
 
 static struct kobj_type ktype_device = {