LXR linux/tools/arch/x86/include/asm/atomic.h

   1/* SPDX-License-Identifier: GPL-2.0 */
   2#ifndef _TOOLS_LINUX_ASM_X86_ATOMIC_H
   3#define _TOOLS_LINUX_ASM_X86_ATOMIC_H
   4
   5#include <linux/compiler.h>
   6#include <linux/types.h>
   7#include "rmwcc.h"
   8
   9#define LOCK_PREFIX "\n\tlock; "
  10
  11#include <asm/cmpxchg.h>
  12
  13/*
  14 * Atomic operations that C can't guarantee us.  Useful for
  15 * resource counting etc..
  16 */
  17
  18#define ATOMIC_INIT(i)  { (i) }
  19
  20/**
  21 * atomic_read - read atomic variable
  22 * @v: pointer of type atomic_t
  23 *
  24 * Atomically reads the value of @v.
  25 */
  26static inline int atomic_read(const atomic_t *v)
  27{
  28        return READ_ONCE((v)->counter);
  29}
  30
  31/**
  32 * atomic_set - set atomic variable
  33 * @v: pointer of type atomic_t
  34 * @i: required value
  35 *
  36 * Atomically sets the value of @v to @i.
  37 */
  38static inline void atomic_set(atomic_t *v, int i)
  39{
  40        v->counter = i;
  41}
  42
  43/**
  44 * atomic_inc - increment atomic variable
  45 * @v: pointer of type atomic_t
  46 *
  47 * Atomically increments @v by 1.
  48 */
  49static inline void atomic_inc(atomic_t *v)
  50{
  51        asm volatile(LOCK_PREFIX "incl %0"
  52                     : "+m" (v->counter));
  53}
  54
  55/**
  56 * atomic_dec_and_test - decrement and test
  57 * @v: pointer of type atomic_t
  58 *
  59 * Atomically decrements @v by 1 and
  60 * returns true if the result is 0, or false for all other
  61 * cases.
  62 */
  63static inline int atomic_dec_and_test(atomic_t *v)
  64{
  65        GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
  66}
  67
  68static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
  69{
  70        return cmpxchg(&v->counter, old, new);
  71}
  72
  73#endif /* _TOOLS_LINUX_ASM_X86_ATOMIC_H */
  74