| 1 | /* |
| 2 | * kref.c - library routines for handling generic reference counted objects |
| 3 | * |
| 4 | * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com> |
| 5 | * Copyright (C) 2004 IBM Corp. |
| 6 | * |
| 7 | * based on lib/kobject.c which was: |
| 8 | * Copyright (C) 2002-2003 Patrick Mochel <mochel@osdl.org> |
| 9 | * |
| 10 | * This file is released under the GPLv2. |
| 11 | * |
| 12 | */ |
| 13 | |
| 14 | //#include "<kernelcompat.h>" |
| 15 | #include <kref.h> |
| 16 | //ust// #include <linux/module.h> |
| 17 | #include "usterr.h" |
| 18 | #include "compiler.h" |
| 19 | |
| 20 | /** |
| 21 | * kref_set - initialize object and set refcount to requested number. |
| 22 | * @kref: object in question. |
| 23 | * @num: initial reference counter |
| 24 | */ |
| 25 | void kref_set(struct kref *kref, int num) |
| 26 | { |
| 27 | atomic_set(&kref->refcount, num); |
| 28 | smp_mb(); |
| 29 | } |
| 30 | |
| 31 | /** |
| 32 | * kref_init - initialize object. |
| 33 | * @kref: object in question. |
| 34 | */ |
| 35 | void kref_init(struct kref *kref) |
| 36 | { |
| 37 | kref_set(kref, 1); |
| 38 | } |
| 39 | |
| 40 | /** |
| 41 | * kref_get - increment refcount for object. |
| 42 | * @kref: object. |
| 43 | */ |
| 44 | void kref_get(struct kref *kref) |
| 45 | { |
| 46 | WARN_ON(!atomic_read(&kref->refcount)); |
| 47 | atomic_inc(&kref->refcount); |
| 48 | smp_mb__after_atomic_inc(); |
| 49 | } |
| 50 | |
| 51 | /** |
| 52 | * kref_put - decrement refcount for object. |
| 53 | * @kref: object. |
| 54 | * @release: pointer to the function that will clean up the object when the |
| 55 | * last reference to the object is released. |
| 56 | * This pointer is required, and it is not acceptable to pass kfree |
| 57 | * in as this function. |
| 58 | * |
| 59 | * Decrement the refcount, and if 0, call release(). |
| 60 | * Return 1 if the object was removed, otherwise return 0. Beware, if this |
| 61 | * function returns 0, you still can not count on the kref from remaining in |
| 62 | * memory. Only use the return value if you want to see if the kref is now |
| 63 | * gone, not present. |
| 64 | */ |
| 65 | int kref_put(struct kref *kref, void (*release)(struct kref *kref)) |
| 66 | { |
| 67 | WARN_ON(release == NULL); |
| 68 | //ust// WARN_ON(release == (void (*)(struct kref *))kfree); |
| 69 | |
| 70 | if (atomic_dec_and_test(&kref->refcount)) { |
| 71 | release(kref); |
| 72 | return 1; |
| 73 | } |
| 74 | return 0; |
| 75 | } |
| 76 | |
| 77 | //ust// EXPORT_SYMBOL(kref_set); |
| 78 | //ust// EXPORT_SYMBOL(kref_init); |
| 79 | //ust// EXPORT_SYMBOL(kref_get); |
| 80 | //ust// EXPORT_SYMBOL(kref_put); |