2 * kref.c - library routines for handling generic reference counted objects
4 * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
5 * Copyright (C) 2004 IBM Corp.
7 * based on lib/kobject.c which was:
8 * Copyright (C) 2002-2003 Patrick Mochel <mochel@osdl.org>
10 * This file is released under the GPLv2.
14 #include <linux/kref.h>
15 #include <linux/module.h>
18 * kref_init - initialize object.
19 * @kref: object in question.
21 void kref_init(struct kref
*kref
)
23 atomic_set(&kref
->refcount
,1);
28 * kref_get - increment refcount for object.
31 void kref_get(struct kref
*kref
)
33 WARN_ON(!atomic_read(&kref
->refcount
));
34 atomic_inc(&kref
->refcount
);
35 smp_mb__after_atomic_inc();
39 * kref_put - decrement refcount for object.
41 * @release: pointer to the function that will clean up the object when the
42 * last reference to the object is released.
43 * This pointer is required, and it is not acceptable to pass kfree
44 * in as this function.
46 * Decrement the refcount, and if 0, call release().
47 * Return 1 if the object was removed, otherwise return 0. Beware, if this
48 * function returns 0, you still can not count on the kref from remaining in
49 * memory. Only use the return value if you want to see if the kref is now
52 int kref_put(struct kref
*kref
, void (*release
)(struct kref
*kref
))
54 WARN_ON(release
== NULL
);
55 WARN_ON(release
== (void (*)(struct kref
*))kfree
);
57 if (atomic_dec_and_test(&kref
->refcount
)) {
64 EXPORT_SYMBOL(kref_init
);
65 EXPORT_SYMBOL(kref_get
);
66 EXPORT_SYMBOL(kref_put
);
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