root/arch/x86/include/asm/local.h

INCLUDED FROM

DEFINITIONS

1. local_inc
2. local_dec
3. local_add
4. local_sub
5. local_sub_and_test
6. local_dec_and_test
7. local_inc_and_test
8. local_add_negative
9. local_add_return
10. local_sub_return

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2 #ifndef _ASM_X86_LOCAL_H
   3 #define _ASM_X86_LOCAL_H
   4 
   5 #include <linux/percpu.h>
   6 
   7 #include <linux/atomic.h>
   8 #include <asm/asm.h>
   9 
  10 typedef struct {
  11         atomic_long_t a;
  12 } local_t;
  13 
  14 #define LOCAL_INIT(i)   { ATOMIC_LONG_INIT(i) }
  15 
  16 #define local_read(l)   atomic_long_read(&(l)->a)
  17 #define local_set(l, i) atomic_long_set(&(l)->a, (i))
  18 
  19 static inline void local_inc(local_t *l)
  20 {
  21         asm volatile(_ASM_INC "%0"
  22                      : "+m" (l->a.counter));
  23 }
  24 
  25 static inline void local_dec(local_t *l)
  26 {
  27         asm volatile(_ASM_DEC "%0"
  28                      : "+m" (l->a.counter));
  29 }
  30 
  31 static inline void local_add(long i, local_t *l)
  32 {
  33         asm volatile(_ASM_ADD "%1,%0"
  34                      : "+m" (l->a.counter)
  35                      : "ir" (i));
  36 }
  37 
  38 static inline void local_sub(long i, local_t *l)
  39 {
  40         asm volatile(_ASM_SUB "%1,%0"
  41                      : "+m" (l->a.counter)
  42                      : "ir" (i));
  43 }
  44 
  45 /**
  46  * local_sub_and_test - subtract value from variable and test result
  47  * @i: integer value to subtract
  48  * @l: pointer to type local_t
  49  *
  50  * Atomically subtracts @i from @l and returns
  51  * true if the result is zero, or false for all
  52  * other cases.
  53  */
  54 static inline bool local_sub_and_test(long i, local_t *l)
  55 {
  56         return GEN_BINARY_RMWcc(_ASM_SUB, l->a.counter, e, "er", i);
  57 }
  58 
  59 /**
  60  * local_dec_and_test - decrement and test
  61  * @l: pointer to type local_t
  62  *
  63  * Atomically decrements @l by 1 and
  64  * returns true if the result is 0, or false for all other
  65  * cases.
  66  */
  67 static inline bool local_dec_and_test(local_t *l)
  68 {
  69         return GEN_UNARY_RMWcc(_ASM_DEC, l->a.counter, e);
  70 }
  71 
  72 /**
  73  * local_inc_and_test - increment and test
  74  * @l: pointer to type local_t
  75  *
  76  * Atomically increments @l by 1
  77  * and returns true if the result is zero, or false for all
  78  * other cases.
  79  */
  80 static inline bool local_inc_and_test(local_t *l)
  81 {
  82         return GEN_UNARY_RMWcc(_ASM_INC, l->a.counter, e);
  83 }
  84 
  85 /**
  86  * local_add_negative - add and test if negative
  87  * @i: integer value to add
  88  * @l: pointer to type local_t
  89  *
  90  * Atomically adds @i to @l and returns true
  91  * if the result is negative, or false when
  92  * result is greater than or equal to zero.
  93  */
  94 static inline bool local_add_negative(long i, local_t *l)
  95 {
  96         return GEN_BINARY_RMWcc(_ASM_ADD, l->a.counter, s, "er", i);
  97 }
  98 
  99 /**
 100  * local_add_return - add and return
 101  * @i: integer value to add
 102  * @l: pointer to type local_t
 103  *
 104  * Atomically adds @i to @l and returns @i + @l
 105  */
 106 static inline long local_add_return(long i, local_t *l)
 107 {
 108         long __i = i;
 109         asm volatile(_ASM_XADD "%0, %1;"
 110                      : "+r" (i), "+m" (l->a.counter)
 111                      : : "memory");
 112         return i + __i;
 113 }
 114 
 115 static inline long local_sub_return(long i, local_t *l)
 116 {
 117         return local_add_return(-i, l);
 118 }
 119 
 120 #define local_inc_return(l)  (local_add_return(1, l))
 121 #define local_dec_return(l)  (local_sub_return(1, l))
 122 
 123 #define local_cmpxchg(l, o, n) \
 124         (cmpxchg_local(&((l)->a.counter), (o), (n)))
 125 /* Always has a lock prefix */
 126 #define local_xchg(l, n) (xchg(&((l)->a.counter), (n)))
 127 
 128 /**
 129  * local_add_unless - add unless the number is a given value
 130  * @l: pointer of type local_t
 131  * @a: the amount to add to l...
 132  * @u: ...unless l is equal to u.
 133  *
 134  * Atomically adds @a to @l, so long as it was not @u.
 135  * Returns non-zero if @l was not @u, and zero otherwise.
 136  */
 137 #define local_add_unless(l, a, u)                               \
 138 ({                                                              \
 139         long c, old;                                            \
 140         c = local_read((l));                                    \
 141         for (;;) {                                              \
 142                 if (unlikely(c == (u)))                         \
 143                         break;                                  \
 144                 old = local_cmpxchg((l), c, c + (a));           \
 145                 if (likely(old == c))                           \
 146                         break;                                  \
 147                 c = old;                                        \
 148         }                                                       \
 149         c != (u);                                               \
 150 })
 151 #define local_inc_not_zero(l) local_add_unless((l), 1, 0)
 152 
 153 /* On x86_32, these are no better than the atomic variants.
 154  * On x86-64 these are better than the atomic variants on SMP kernels
 155  * because they dont use a lock prefix.
 156  */
 157 #define __local_inc(l)          local_inc(l)
 158 #define __local_dec(l)          local_dec(l)
 159 #define __local_add(i, l)       local_add((i), (l))
 160 #define __local_sub(i, l)       local_sub((i), (l))
 161 
 162 #endif /* _ASM_X86_LOCAL_H */