1 /*
2 * Copyright (c) 2013, Google, Inc. All rights reserved
3 *
4 * Permission is hereby granted, free of charge, to any person obtaining
5 * a copy of this software and associated documentation files
6 * (the "Software"), to deal in the Software without restriction,
7 * including without limitation the rights to use, copy, modify, merge,
8 * publish, distribute, sublicense, and/or sell copies of the Software,
9 * and to permit persons to whom the Software is furnished to do so,
10 * subject to the following conditions:
11 *
12 * The above copyright notice and this permission notice shall be
13 * included in all copies or substantial portions of the Software.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
18 * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
19 * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
20 * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
21 * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
22 */
23
24 #ifndef __REFCOUNT_H
25 #define __REFCOUNT_H
26
27 #include <arch/ops.h>
28 #include <compiler.h>
29 #include <limits.h>
30 #include <panic.h>
31
32 struct refcount {
33 volatile int cnt;
34 };
35
36 typedef void (*refcount_destroy_func)(struct refcount* ref);
37
refcount_init(struct refcount * ref)38 static inline __ALWAYS_INLINE void refcount_init(struct refcount* ref) {
39 /* TODO: silly, but don't have atomic_set, or a clean
40 * write barrier */
41 atomic_and(&ref->cnt, 0);
42 atomic_add(&ref->cnt, 1);
43 }
44
refcount_inc(struct refcount * ref)45 static inline __ALWAYS_INLINE void refcount_inc(struct refcount* ref) {
46 if (atomic_add(&ref->cnt, 1) == INT_MAX) {
47 panic("ref overflow\n");
48 }
49 }
50
refcount_dec(struct refcount * ref,refcount_destroy_func destroy)51 static inline __ALWAYS_INLINE void refcount_dec(struct refcount* ref,
52 refcount_destroy_func destroy) {
53 /* decerementing from 1? destroy */
54 if (atomic_add(&ref->cnt, -1) == 1)
55 destroy(ref);
56 }
57
58 #endif
59