include/asm-generic/atomic.h

   1 /*
   2  * Generic C implementation of atomic counter operations
   3  * Originally implemented for MN10300.
   4  *
   5  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   6  * Written by David Howells (dhowells@redhat.com)
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public Licence
  10  * as published by the Free Software Foundation; either version
  11  * 2 of the Licence, or (at your option) any later version.
  12  */
  13 #ifndef __ASM_GENERIC_ATOMIC_H
  14 #define __ASM_GENERIC_ATOMIC_H
  15
  16 #ifdef CONFIG_SMP
  17 #error not SMP safe
  18 #endif
  19
  20 /*
  21  * Atomic operations that C can't guarantee us.  Useful for
  22  * resource counting etc..
  23  */
  24
  25 #define ATOMIC_INIT(i)  { (i) }
  26
  27 #ifdef __KERNEL__
  28
  29 /**
  30  * atomic_read - read atomic variable
  31  * @v: pointer of type atomic_t
  32  *
  33  * Atomically reads the value of @v.
  34  */
  35 #define atomic_read(v)  (*(volatile int *)&(v)->counter)
  36
  37 /**
  38  * atomic_set - set atomic variable
  39  * @v: pointer of type atomic_t
  40  * @i: required value
  41  *
  42  * Atomically sets the value of @v to @i.
  43  */
  44 #define atomic_set(v, i) (((v)->counter) = (i))
  45
  46 #include <asm/system.h>
  47
  48 /**
  49  * atomic_add_return - add integer to atomic variable
  50  * @i: integer value to add
  51  * @v: pointer of type atomic_t
  52  *
  53  * Atomically adds @i to @v and returns the result
  54  */
  55 static inline int atomic_add_return(int i, atomic_t *v)
  56 {
  57         unsigned long flags;
  58         int temp;
  59
  60         raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
  61         temp = v->counter;
  62         temp += i;
  63         v->counter = temp;
  64         raw_local_irq_restore(flags);
  65
  66         return temp;
  67 }
  68
  69 /**
  70  * atomic_sub_return - subtract integer from atomic variable
  71  * @i: integer value to subtract
  72  * @v: pointer of type atomic_t
  73  *
  74  * Atomically subtracts @i from @v and returns the result
  75  */
  76 static inline int atomic_sub_return(int i, atomic_t *v)
  77 {
  78         unsigned long flags;
  79         int temp;
  80
  81         raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
  82         temp = v->counter;
  83         temp -= i;
  84         v->counter = temp;
  85         raw_local_irq_restore(flags);
  86
  87         return temp;
  88 }
  89
  90 static inline int atomic_add_negative(int i, atomic_t *v)
  91 {
  92         return atomic_add_return(i, v) < 0;
  93 }
  94
  95 static inline void atomic_add(int i, atomic_t *v)
  96 {
  97         atomic_add_return(i, v);
  98 }
  99
 100 static inline void atomic_sub(int i, atomic_t *v)
 101 {
 102         atomic_sub_return(i, v);
 103 }
 104
 105 static inline void atomic_inc(atomic_t *v)
 106 {
 107         atomic_add_return(1, v);
 108 }
 109
 110 static inline void atomic_dec(atomic_t *v)
 111 {
 112         atomic_sub_return(1, v);
 113 }
 114
 115 #define atomic_dec_return(v)            atomic_sub_return(1, (v))
 116 #define atomic_inc_return(v)            atomic_add_return(1, (v))
 117
 118 #define atomic_sub_and_test(i, v)       (atomic_sub_return((i), (v)) == 0)
 119 #define atomic_dec_and_test(v)          (atomic_sub_return(1, (v)) == 0)
 120 #define atomic_inc_and_test(v)          (atomic_add_return(1, (v)) == 0)
 121
 122 #define atomic_add_unless(v, a, u)                              \
 123 ({                                                              \
 124         int c, old;                                             \
 125         c = atomic_read(v);                                     \
 126         while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
 127                 c = old;                                        \
 128         c != (u);                                               \
 129 })
 130
 131 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
 132
 133 static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr)
 134 {
 135         unsigned long flags;
 136
 137         mask = ~mask;
 138         raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */
 139         *addr &= mask;
 140         raw_local_irq_restore(flags);
 141 }
 142
 143 #define atomic_xchg(ptr, v)             (xchg(&(ptr)->counter, (v)))
 144 #define atomic_cmpxchg(v, old, new)     (cmpxchg(&((v)->counter), (old), (new)))
 145
 146 #define cmpxchg_local(ptr, o, n)                                               \
 147         ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
 148                         (unsigned long)(n), sizeof(*(ptr))))
 149
 150 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
 151
 152 /* Assume that atomic operations are already serializing */
 153 #define smp_mb__before_atomic_dec()     barrier()
 154 #define smp_mb__after_atomic_dec()      barrier()
 155 #define smp_mb__before_atomic_inc()     barrier()
 156 #define smp_mb__after_atomic_inc()      barrier()
 157
 158 #include <asm-generic/atomic-long.h>
 159
 160 #endif /* __KERNEL__ */
 161 #endif /* __ASM_GENERIC_ATOMIC_H */