tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1#ifndef _TOOLS_LINUX_ASM_X86_ATOMIC_H
2#define _TOOLS_LINUX_ASM_X86_ATOMIC_H
3
4#include <linux/compiler.h>
5#include <linux/types.h>
6#include "rmwcc.h"
7
8#define LOCK_PREFIX "\n\tlock; "
9
10#include <asm/cmpxchg.h>
11
12/*
13 * Atomic operations that C can't guarantee us. Useful for
14 * resource counting etc..
15 */
16
17#define ATOMIC_INIT(i) { (i) }
18
19/**
20 * atomic_read - read atomic variable
21 * @v: pointer of type atomic_t
22 *
23 * Atomically reads the value of @v.
24 */
25static inline int atomic_read(const atomic_t *v)
26{
27 return ACCESS_ONCE((v)->counter);
28}
29
30/**
31 * atomic_set - set atomic variable
32 * @v: pointer of type atomic_t
33 * @i: required value
34 *
35 * Atomically sets the value of @v to @i.
36 */
37static inline void atomic_set(atomic_t *v, int i)
38{
39 v->counter = i;
40}
41
42/**
43 * atomic_inc - increment atomic variable
44 * @v: pointer of type atomic_t
45 *
46 * Atomically increments @v by 1.
47 */
48static inline void atomic_inc(atomic_t *v)
49{
50 asm volatile(LOCK_PREFIX "incl %0"
51 : "+m" (v->counter));
52}
53
54/**
55 * atomic_dec_and_test - decrement and test
56 * @v: pointer of type atomic_t
57 *
58 * Atomically decrements @v by 1 and
59 * returns true if the result is 0, or false for all other
60 * cases.
61 */
62static inline int atomic_dec_and_test(atomic_t *v)
63{
64 GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
65}
66
67static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
68{
69 return cmpxchg(&v->counter, old, new);
70}
71
72#endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */