1 /* Atomic operations usable in machine independent code */
2 #ifndef _LINUX_ATOMIC_H
3 #define _LINUX_ATOMIC_H
4 #include <asm/atomic.h>
5
6 /**
7 * atomic_add_unless - add unless the number is already a given value
8 * @v: pointer of type atomic_t
9 * @a: the amount to add to v...
10 * @u: ...unless v is equal to u.
11 *
12 * Atomically adds @a to @v, so long as @v was not already @u.
13 * Returns non-zero if @v was not @u, and zero otherwise.
14 */
atomic_add_unless(atomic_t * v,int a,int u)15 static inline int atomic_add_unless(atomic_t *v, int a, int u)
16 {
17 return __atomic_add_unless(v, a, u) != u;
18 }
19
20 /**
21 * atomic_inc_not_zero - increment unless the number is zero
22 * @v: pointer of type atomic_t
23 *
24 * Atomically increments @v by 1, so long as @v is non-zero.
25 * Returns non-zero if @v was non-zero, and zero otherwise.
26 */
27 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
28
29 /**
30 * atomic_inc_not_zero_hint - increment if not null
31 * @v: pointer of type atomic_t
32 * @hint: probable value of the atomic before the increment
33 *
34 * This version of atomic_inc_not_zero() gives a hint of probable
35 * value of the atomic. This helps processor to not read the memory
36 * before doing the atomic read/modify/write cycle, lowering
37 * number of bus transactions on some arches.
38 *
39 * Returns: 0 if increment was not done, 1 otherwise.
40 */
41 #ifndef atomic_inc_not_zero_hint
atomic_inc_not_zero_hint(atomic_t * v,int hint)42 static inline int atomic_inc_not_zero_hint(atomic_t *v, int hint)
43 {
44 int val, c = hint;
45
46 /* sanity test, should be removed by compiler if hint is a constant */
47 if (!hint)
48 return atomic_inc_not_zero(v);
49
50 do {
51 val = atomic_cmpxchg(v, c, c + 1);
52 if (val == c)
53 return 1;
54 c = val;
55 } while (c);
56
57 return 0;
58 }
59 #endif
60
61 #ifndef atomic_inc_unless_negative
atomic_inc_unless_negative(atomic_t * p)62 static inline int atomic_inc_unless_negative(atomic_t *p)
63 {
64 int v, v1;
65 for (v = 0; v >= 0; v = v1) {
66 v1 = atomic_cmpxchg(p, v, v + 1);
67 if (likely(v1 == v))
68 return 1;
69 }
70 return 0;
71 }
72 #endif
73
74 #ifndef atomic_dec_unless_positive
atomic_dec_unless_positive(atomic_t * p)75 static inline int atomic_dec_unless_positive(atomic_t *p)
76 {
77 int v, v1;
78 for (v = 0; v <= 0; v = v1) {
79 v1 = atomic_cmpxchg(p, v, v - 1);
80 if (likely(v1 == v))
81 return 1;
82 }
83 return 0;
84 }
85 #endif
86
87 #ifndef CONFIG_ARCH_HAS_ATOMIC_OR
atomic_or(int i,atomic_t * v)88 static inline void atomic_or(int i, atomic_t *v)
89 {
90 int old;
91 int new;
92
93 do {
94 old = atomic_read(v);
95 new = old | i;
96 } while (atomic_cmpxchg(v, old, new) != old);
97 }
98 #endif /* #ifndef CONFIG_ARCH_HAS_ATOMIC_OR */
99
100 #include <asm-generic/atomic-long.h>
101 #ifdef CONFIG_GENERIC_ATOMIC64
102 #include <asm-generic/atomic64.h>
103 #endif
104 #endif /* _LINUX_ATOMIC_H */
105