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
   9 typedef 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
  18 static inline void local_inc(local_t *l)
  19 {
  20         asm volatile(_ASM_INC "%0"
  21                      : "+m" (l->a.counter));
  22 }
  23
  24 static inline void local_dec(local_t *l)
  25 {
  26         asm volatile(_ASM_DEC "%0"
  27                      : "+m" (l->a.counter));
  28 }
  29
  30 static 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
  37 static 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  */
  53 static 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  */
  66 static 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  */
  79 static 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  */
  93 static 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  */
 105 static 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
 114 static 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 */