Kobject: auto-cleanup on final unref

We save the current state in the object itself, so we can do proper
cleanup when the last reference is dropped.

If the initial reference is dropped, the object will be removed from
sysfs if needed, if an "add" event was sent, "remove" will be send, and
the allocated resources are released.

This allows us to clean up some driver core usage as well as allowing us
to do other such changes to the rest of the kernel.

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

1 files changed, 7 insertions, 25 deletions

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 675a719dcdd..d5d542db96f 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -576,8 +576,8 @@ static struct kobject *get_device_parent(struct device *dev,
 
 		/*
 		 * If we have no parent, we live in "virtual".
-		 * Class-devices with a bus-device as parent, live
-		 * in a class-directory to prevent namespace collisions.
+		 * Class-devices with a non class-device as parent, live
+		 * in a "glue" directory to prevent namespace collisions.
 		 */
 		if (parent == NULL)
 			parent_kobj = virtual_device_parent(dev);
@@ -607,8 +607,7 @@ static struct kobject *get_device_parent(struct device *dev,
 			kobject_put(k);
 			return NULL;
 		}
-		/* Do not emit a uevent, as it's not needed for this
-		 * "class glue" directory. */
+		/* do not emit an uevent for this simple "glue" directory */
 		return k;
 	}
 
@@ -619,30 +618,13 @@ static struct kobject *get_device_parent(struct device *dev,
 
 static void cleanup_device_parent(struct device *dev)
 {
-	struct device *d;
-	int other = 0;
+	struct kobject *glue_dir = dev->kobj.parent;
 
-	if (!dev->class)
-		return;
-
-	/* see if we live in a parent class directory */
-	if (dev->kobj.parent->kset != &dev->class->class_dirs)
+	/* see if we live in a "glue" directory */
+	if (!dev->class || glue_dir->kset != &dev->class->class_dirs)
 		return;
 
-	/* if we are the last child of our class, delete the directory */
-	down(&dev->class->sem);
-	list_for_each_entry(d, &dev->class->devices, node) {
-		if (d == dev)
-			continue;
-		if (d->kobj.parent == dev->kobj.parent) {
-			other = 1;
-			break;
-		}
-	}
-	if (!other)
-		kobject_del(dev->kobj.parent);
-	kobject_put(dev->kobj.parent);
-	up(&dev->class->sem);
+	kobject_put(glue_dir);
 }
 #endif