Linux kernel mirror (for testing)
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linux
1#ifndef _LINUX_REFCOUNT_H
2#define _LINUX_REFCOUNT_H
3
4#include <linux/atomic.h>
5#include <linux/mutex.h>
6#include <linux/spinlock.h>
7#include <linux/kernel.h>
8
9/**
10 * refcount_t - variant of atomic_t specialized for reference counts
11 * @refs: atomic_t counter field
12 *
13 * The counter saturates at UINT_MAX and will not move once
14 * there. This avoids wrapping the counter and causing 'spurious'
15 * use-after-free bugs.
16 */
17typedef struct refcount_struct {
18 atomic_t refs;
19} refcount_t;
20
21#define REFCOUNT_INIT(n) { .refs = ATOMIC_INIT(n), }
22
23/**
24 * refcount_set - set a refcount's value
25 * @r: the refcount
26 * @n: value to which the refcount will be set
27 */
28static inline void refcount_set(refcount_t *r, unsigned int n)
29{
30 atomic_set(&r->refs, n);
31}
32
33/**
34 * refcount_read - get a refcount's value
35 * @r: the refcount
36 *
37 * Return: the refcount's value
38 */
39static inline unsigned int refcount_read(const refcount_t *r)
40{
41 return atomic_read(&r->refs);
42}
43
44#ifdef CONFIG_REFCOUNT_FULL
45extern __must_check bool refcount_add_not_zero(unsigned int i, refcount_t *r);
46extern void refcount_add(unsigned int i, refcount_t *r);
47
48extern __must_check bool refcount_inc_not_zero(refcount_t *r);
49extern void refcount_inc(refcount_t *r);
50
51extern __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r);
52
53extern __must_check bool refcount_dec_and_test(refcount_t *r);
54extern void refcount_dec(refcount_t *r);
55#else
56static inline __must_check bool refcount_add_not_zero(unsigned int i, refcount_t *r)
57{
58 return atomic_add_unless(&r->refs, i, 0);
59}
60
61static inline void refcount_add(unsigned int i, refcount_t *r)
62{
63 atomic_add(i, &r->refs);
64}
65
66static inline __must_check bool refcount_inc_not_zero(refcount_t *r)
67{
68 return atomic_add_unless(&r->refs, 1, 0);
69}
70
71static inline void refcount_inc(refcount_t *r)
72{
73 atomic_inc(&r->refs);
74}
75
76static inline __must_check bool refcount_sub_and_test(unsigned int i, refcount_t *r)
77{
78 return atomic_sub_and_test(i, &r->refs);
79}
80
81static inline __must_check bool refcount_dec_and_test(refcount_t *r)
82{
83 return atomic_dec_and_test(&r->refs);
84}
85
86static inline void refcount_dec(refcount_t *r)
87{
88 atomic_dec(&r->refs);
89}
90#endif /* CONFIG_REFCOUNT_FULL */
91
92extern __must_check bool refcount_dec_if_one(refcount_t *r);
93extern __must_check bool refcount_dec_not_one(refcount_t *r);
94extern __must_check bool refcount_dec_and_mutex_lock(refcount_t *r, struct mutex *lock);
95extern __must_check bool refcount_dec_and_lock(refcount_t *r, spinlock_t *lock);
96
97#endif /* _LINUX_REFCOUNT_H */