LXR linux/arch/x86/include/asm/local.h

   1#ifndef _ASM_X86_LOCAL_H
   2#define _ASM_X86_LOCAL_H
   3
   4#include <linux/percpu.h>
   5
   6#include <linux/atomic.h>
   7#include <asm/asm.h>
   8
   9typedef struct {
  10        atomic_long_t a;
  11} local_t;
  12
  13#define LOCAL_INIT(i)   { ATOMIC_LONG_INIT(i) }
  14
  15#define local_read(l)   atomic_long_read(&(l)->a)
  16#define local_set(l, i) atomic_long_set(&(l)->a, (i))
  17
  18static inline void local_inc(local_t *l)
  19{
  20        asm volatile(_ASM_INC "%0"
  21                     : "+m" (l->a.counter));
  22}
  23
  24static inline void local_dec(local_t *l)
  25{
  26        asm volatile(_ASM_DEC "%0"
  27                     : "+m" (l->a.counter));
  28}
  29
  30static inline void local_add(long i, local_t *l)
  31{
  32        asm volatile(_ASM_ADD "%1,%0"
  33                     : "+m" (l->a.counter)
  34                     : "ir" (i));
  35}
  36
  37static inline void local_sub(long i, local_t *l)
  38{
  39        asm volatile(_ASM_SUB "%1,%0"
  40                     : "+m" (l->a.counter)
  41                     : "ir" (i));
  42}
  43
  44/**
  45 * local_sub_and_test - subtract value from variable and test result
  46 * @i: integer value to subtract
  47 * @l: pointer to type local_t
  48 *
  49 * Atomically subtracts @i from @l and returns
  50 * true if the result is zero, or false for all
  51 * other cases.
  52 */
  53static inline int local_sub_and_test(long i, local_t *l)
  54{
  55        GEN_BINARY_RMWcc(_ASM_SUB, l->a.counter, "er", i, "%0", "e");
  56}
  57
  58/**
  59 * local_dec_and_test - decrement and test
  60 * @l: pointer to type local_t
  61 *
  62 * Atomically decrements @l by 1 and
  63 * returns true if the result is 0, or false for all other
  64 * cases.
  65 */
  66static inline int local_dec_and_test(local_t *l)
  67{
  68        GEN_UNARY_RMWcc(_ASM_DEC, l->a.counter, "%0", "e");
  69}
  70
  71/**
  72 * local_inc_and_test - increment and test
  73 * @l: pointer to type local_t
  74 *
  75 * Atomically increments @l by 1
  76 * and returns true if the result is zero, or false for all
  77 * other cases.
  78 */
  79static inline int local_inc_and_test(local_t *l)
  80{
  81        GEN_UNARY_RMWcc(_ASM_INC, l->a.counter, "%0", "e");
  82}
  83
  84/**
  85 * local_add_negative - add and test if negative
  86 * @i: integer value to add
  87 * @l: pointer to type local_t
  88 *
  89 * Atomically adds @i to @l and returns true
  90 * if the result is negative, or false when
  91 * result is greater than or equal to zero.
  92 */
  93static inline int local_add_negative(long i, local_t *l)
  94{
  95        GEN_BINARY_RMWcc(_ASM_ADD, l->a.counter, "er", i, "%0", "s");
  96}
  97
  98/**
  99 * local_add_return - add and return
 100 * @i: integer value to add
 101 * @l: pointer to type local_t
 102 *
 103 * Atomically adds @i to @l and returns @i + @l
 104 */
 105static inline long local_add_return(long i, local_t *l)
 106{
 107        long __i = i;
 108        asm volatile(_ASM_XADD "%0, %1;"
 109                     : "+r" (i), "+m" (l->a.counter)
 110                     : : "memory");
 111        return i + __i;
 112}
 113
 114static inline long local_sub_return(long i, local_t *l)
 115{
 116        return local_add_return(-i, l);
 117}
 118
 119#define local_inc_return(l)  (local_add_return(1, l))
 120#define local_dec_return(l)  (local_sub_return(1, l))
 121
 122#define local_cmpxchg(l, o, n) \
 123        (cmpxchg_local(&((l)->a.counter), (o), (n)))
 124/* Always has a lock prefix */
 125#define local_xchg(l, n) (xchg(&((l)->a.counter), (n)))
 126
 127/**
 128 * local_add_unless - add unless the number is a given value
 129 * @l: pointer of type local_t
 130 * @a: the amount to add to l...
 131 * @u: ...unless l is equal to u.
 132 *
 133 * Atomically adds @a to @l, so long as it was not @u.
 134 * Returns non-zero if @l was not @u, and zero otherwise.
 135 */
 136#define local_add_unless(l, a, u)                               \
 137({                                                              \
 138        long c, old;                                            \
 139        c = local_read((l));                                    \
 140        for (;;) {                                              \
 141                if (unlikely(c == (u)))                         \
 142                        break;                                  \
 143                old = local_cmpxchg((l), c, c + (a));           \
 144                if (likely(old == c))                           \
 145                        break;                                  \
 146                c = old;                                        \
 147        }                                                       \
 148        c != (u);                                               \
 149})
 150#define local_inc_not_zero(l) local_add_unless((l), 1, 0)
 151
 152/* On x86_32, these are no better than the atomic variants.
 153 * On x86-64 these are better than the atomic variants on SMP kernels
 154 * because they dont use a lock prefix.
 155 */
 156#define __local_inc(l)          local_inc(l)
 157#define __local_dec(l)          local_dec(l)
 158#define __local_add(i, l)       local_add((i), (l))
 159#define __local_sub(i, l)       local_sub((i), (l))
 160
 161#endif /* _ASM_X86_LOCAL_H */
 162