/* * kref.c - library routines for handling generic reference counted objects * * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com> * Copyright (C) 2004 IBM Corp. * * based on lib/kobject.c which was: * Copyright (C) 2002-2003 Patrick Mochel <mochel@osdl.org> * * This file is released under the GPLv2. * */ #include <linux/kref.h>#include <linux/module.h> /** * kref_init - initialize object. * @kref: object in question. */void kref_init(struct kref *kref){	atomic_set(&kref->refcount,1);} /** * kref_get - increment refcount for object. * @kref: object. */void kref_get(struct kref *kref){	WARN_ON(!atomic_read(&kref->refcount));	atomic_inc(&kref->refcount);} /** * kref_put - decrement refcount for object. * @kref: object. * @release: pointer to the function that will clean up the object when the *	     last reference to the object is released. *	     This pointer is required, and it is not acceptable to pass kfree *	     in as this function. * * Decrement the refcount, and if 0, call release(). * Return 1 if the object was removed, otherwise return 0.  Beware, if this * function returns 0, you still can not count on the kref from remaining in * memory.  Only use the return value if you want to see if the kref is now * gone, not present. */int kref_put(struct kref *kref, void (*release)(struct kref *kref)){	WARN_ON(release == NULL);	WARN_ON(release == (void (*)(struct kref *))kfree); 	/*	 * if current count is one, we are the last user and can release object	 * right now, avoiding an atomic operation on 'refcount'	 */	if ((atomic_read(&kref->refcount) == 1) ||	    (atomic_dec_and_test(&kref->refcount))) {		release(kref);		return 1;	}	return 0;} EXPORT_SYMBOL(kref_init);EXPORT_SYMBOL(kref_get);EXPORT_SYMBOL(kref_put);