1 /* Atomic operations usable in machine independent code */
2 #ifndef _LINUX_ATOMIC_H
3 #define _LINUX_ATOMIC_H
4 #include <asm/atomic.h>
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.
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.
15 static inline int atomic_add_unless(atomic_t
*v
, int a
, int u
)
17 return __atomic_add_unless(v
, a
, u
) != u
;
21 * atomic_inc_not_zero - increment unless the number is zero
22 * @v: pointer of type atomic_t
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.
27 #ifndef atomic_inc_not_zero
28 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
32 * atomic_inc_not_zero_hint - increment if not null
33 * @v: pointer of type atomic_t
34 * @hint: probable value of the atomic before the increment
36 * This version of atomic_inc_not_zero() gives a hint of probable
37 * value of the atomic. This helps processor to not read the memory
38 * before doing the atomic read/modify/write cycle, lowering
39 * number of bus transactions on some arches.
41 * Returns: 0 if increment was not done, 1 otherwise.
43 #ifndef atomic_inc_not_zero_hint
44 static inline int atomic_inc_not_zero_hint(atomic_t
*v
, int hint
)
48 /* sanity test, should be removed by compiler if hint is a constant */
50 return atomic_inc_not_zero(v
);
53 val
= atomic_cmpxchg(v
, c
, c
+ 1);
63 #ifndef atomic_inc_unless_negative
64 static inline int atomic_inc_unless_negative(atomic_t
*p
)
67 for (v
= 0; v
>= 0; v
= v1
) {
68 v1
= atomic_cmpxchg(p
, v
, v
+ 1);
76 #ifndef atomic_dec_unless_positive
77 static inline int atomic_dec_unless_positive(atomic_t
*p
)
80 for (v
= 0; v
<= 0; v
= v1
) {
81 v1
= atomic_cmpxchg(p
, v
, v
- 1);
90 * atomic_dec_if_positive - decrement by 1 if old value positive
91 * @v: pointer of type atomic_t
93 * The function returns the old value of *v minus 1, even if
94 * the atomic variable, v, was not decremented.
96 #ifndef atomic_dec_if_positive
97 static inline int atomic_dec_if_positive(atomic_t
*v
)
103 if (unlikely(dec
< 0))
105 old
= atomic_cmpxchg((v
), c
, dec
);
106 if (likely(old
== c
))
114 #ifndef CONFIG_ARCH_HAS_ATOMIC_OR
115 static inline void atomic_or(int i
, atomic_t
*v
)
121 old
= atomic_read(v
);
123 } while (atomic_cmpxchg(v
, old
, new) != old
);
125 #endif /* #ifndef CONFIG_ARCH_HAS_ATOMIC_OR */
127 #include <asm-generic/atomic-long.h>
128 #ifdef CONFIG_GENERIC_ATOMIC64
129 #include <asm-generic/atomic64.h>
131 #endif /* _LINUX_ATOMIC_H */
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