introduce struct kobject: simple, generic object for embedding in other structures.

This is not meant to be fancy; just something simple for which we can 
control the refcount and other common functionality using common code. 
   
The basic operations for registration and reference count manipulation are
included. 

1 files changed, 98 insertions, 0 deletions

diff --git a/lib/kobject.c b/lib/kobject.c
new file mode 100644
index 000000000000..48e950c9e4ce
--- /dev/null
+++ b/lib/kobject.c
@@ -0,0 +1,98 @@
+/*
+ * kobject.c - library routines for handling generic kernel objects
+ */
+
+#define DEBUG 1
+
+#include <linux/kobject.h>
+#include <linux/module.h>
+#include <linux/stat.h>
+
+/**
+ *	kobject_init - initialize object.
+ *	@kobj:	object in question.
+ */
+
+void kobject_init(struct kobject * kobj)
+{
+	atomic_set(&kobj->refcount,1);
+	INIT_LIST_HEAD(&kobj->entry);
+}
+
+/**
+ *	kobject_register - register an object.
+ *	@kobj:	object in question.
+ *
+ *	For now, fill in the replicated fields in the object's
+ *	directory entry, and create a dir in sysfs. 
+ *	This stuff should go away in the future, as we move
+ *	more implicit things to sysfs.
+ */
+
+int kobject_register(struct kobject * kobj)
+{
+	pr_debug("kobject %s: registering\n",kobj->name);
+	if (kobj->parent)
+		kobject_get(kobj->parent);
+	return 0;
+}
+
+/**
+ *	kobject_unregister - unlink an object.
+ *	@kobj:	object going away.
+ *
+ *	The device has been told to be removed, but may
+ *	not necessarily be disappearing from the kernel.
+ *	So, we remove the directory and decrement the refcount
+ *	that we set with kobject_register().
+ *
+ *	Eventually (maybe now), the refcount will hit 0, and 
+ *	put_device() will clean the device up.
+ */
+
+void kobject_unregister(struct kobject * kobj)
+{
+	pr_debug("kobject %s: unregistering\n",kobj->name);
+	kobject_put(kobj);
+}
+
+/**
+ *	kobject_get - increment refcount for object.
+ *	@kobj:	object.
+ */
+
+struct kobject * kobject_get(struct kobject * kobj)
+{
+	struct kobject * ret = kobj;
+	if (atomic_read(&kobj->refcount) > 0)
+		atomic_inc(&kobj->refcount);
+	else
+		ret = NULL;
+	return ret;
+}
+
+/**
+ *	kobject_put - decrement refcount for object.
+ *	@kobj:	object.
+ *
+ *	Decrement the refcount, and check if 0. If it is, then 
+ *	we're gonna need to clean it up, and decrement the refcount
+ *	of its parent.
+ */
+
+void kobject_put(struct kobject * kobj)
+{
+	struct kobject * parent = kobj->parent;
+
+	if (!atomic_dec_and_test(&kobj->refcount))
+		return;
+	pr_debug("kobject %s: cleaning up\n",kobj->name);
+	if (parent)
+		kobject_put(parent);
+}
+
+EXPORT_SYMBOL(kobject_init);
+EXPORT_SYMBOL(kobject_register);
+EXPORT_SYMBOL(kobject_unregister);
+EXPORT_SYMBOL(kobject_get);
+EXPORT_SYMBOL(kobject_put);