root/tools/arch/x86/include/asm/atomic.h

INCLUDED FROM

DEFINITIONS

1. atomic_read
2. atomic_set
3. atomic_inc
4. atomic_dec_and_test
5. atomic_cmpxchg

   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  */
  26 static 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  */
  38 static 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  */
  49 static 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  */
  63 static inline int atomic_dec_and_test(atomic_t *v)
  64 {
  65         GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
  66 }
  67 
  68 static __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 */