1 /* 2 * Generic C implementation of atomic counter operations. Usable on 3 * UP systems only. Do not include in machine independent code. 4 * 5 * Originally implemented for MN10300. 6 * 7 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. 8 * Written by David Howells (dhowells@redhat.com) 9 * 10 * This program is free software; you can redistribute it and/or 11 * modify it under the terms of the GNU General Public Licence 12 * as published by the Free Software Foundation; either version 13 * 2 of the Licence, or (at your option) any later version. 14 */ 15 #ifndef __ASM_GENERIC_ATOMIC_H 16 #define __ASM_GENERIC_ATOMIC_H 17 18 #include <asm/cmpxchg.h> 19 20 #ifdef CONFIG_SMP 21 /* Force people to define core atomics */ 22 # if !defined(atomic_add_return) || !defined(atomic_sub_return) || \ 23 !defined(atomic_clear_mask) || !defined(atomic_set_mask) 24 # error "SMP requires a little arch-specific magic" 25 # endif 26 #endif 27 28 /* 29 * Atomic operations that C can't guarantee us. Useful for 30 * resource counting etc.. 31 */ 32 33 #define ATOMIC_INIT(i) { (i) } 34 35 #ifdef __KERNEL__ 36 37 /** 38 * atomic_read - read atomic variable 39 * @v: pointer of type atomic_t 40 * 41 * Atomically reads the value of @v. 42 */ 43 #ifndef atomic_read 44 #define atomic_read(v) (*(volatile int *)&(v)->counter) 45 #endif 46 47 /** 48 * atomic_set - set atomic variable 49 * @v: pointer of type atomic_t 50 * @i: required value 51 * 52 * Atomically sets the value of @v to @i. 53 */ 54 #define atomic_set(v, i) (((v)->counter) = (i)) 55 56 #include <linux/irqflags.h> 57 58 /** 59 * atomic_add_return - add integer to atomic variable 60 * @i: integer value to add 61 * @v: pointer of type atomic_t 62 * 63 * Atomically adds @i to @v and returns the result 64 */ 65 #ifndef atomic_add_return 66 static inline int atomic_add_return(int i, atomic_t *v) 67 { 68 unsigned long flags; 69 int temp; 70 71 raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */ 72 temp = v->counter; 73 temp += i; 74 v->counter = temp; 75 raw_local_irq_restore(flags); 76 77 return temp; 78 } 79 #endif 80 81 /** 82 * atomic_sub_return - subtract integer from atomic variable 83 * @i: integer value to subtract 84 * @v: pointer of type atomic_t 85 * 86 * Atomically subtracts @i from @v and returns the result 87 */ 88 #ifndef atomic_sub_return 89 static inline int atomic_sub_return(int i, atomic_t *v) 90 { 91 unsigned long flags; 92 int temp; 93 94 raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */ 95 temp = v->counter; 96 temp -= i; 97 v->counter = temp; 98 raw_local_irq_restore(flags); 99 100 return temp; 101 } 102 #endif 103 104 static inline int atomic_add_negative(int i, atomic_t *v) 105 { 106 return atomic_add_return(i, v) < 0; 107 } 108 109 static inline void atomic_add(int i, atomic_t *v) 110 { 111 atomic_add_return(i, v); 112 } 113 114 static inline void atomic_sub(int i, atomic_t *v) 115 { 116 atomic_sub_return(i, v); 117 } 118 119 static inline void atomic_inc(atomic_t *v) 120 { 121 atomic_add_return(1, v); 122 } 123 124 static inline void atomic_dec(atomic_t *v) 125 { 126 atomic_sub_return(1, v); 127 } 128 129 #define atomic_dec_return(v) atomic_sub_return(1, (v)) 130 #define atomic_inc_return(v) atomic_add_return(1, (v)) 131 132 #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0) 133 #define atomic_dec_and_test(v) (atomic_dec_return(v) == 0) 134 #define atomic_inc_and_test(v) (atomic_inc_return(v) == 0) 135 136 #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) 137 #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) 138 139 #define cmpxchg_local(ptr, o, n) \ 140 ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ 141 (unsigned long)(n), sizeof(*(ptr)))) 142 143 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) 144 145 static inline int __atomic_add_unless(atomic_t *v, int a, int u) 146 { 147 int c, old; 148 c = atomic_read(v); 149 while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c) 150 c = old; 151 return c; 152 } 153 154 /** 155 * atomic_clear_mask - Atomically clear bits in atomic variable 156 * @mask: Mask of the bits to be cleared 157 * @v: pointer of type atomic_t 158 * 159 * Atomically clears the bits set in @mask from @v 160 */ 161 #ifndef atomic_clear_mask 162 static inline void atomic_clear_mask(unsigned long mask, atomic_t *v) 163 { 164 unsigned long flags; 165 166 mask = ~mask; 167 raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ 168 v->counter &= mask; 169 raw_local_irq_restore(flags); 170 } 171 #endif 172 173 /** 174 * atomic_set_mask - Atomically set bits in atomic variable 175 * @mask: Mask of the bits to be set 176 * @v: pointer of type atomic_t 177 * 178 * Atomically sets the bits set in @mask in @v 179 */ 180 #ifndef atomic_set_mask 181 static inline void atomic_set_mask(unsigned int mask, atomic_t *v) 182 { 183 unsigned long flags; 184 185 raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ 186 v->counter |= mask; 187 raw_local_irq_restore(flags); 188 } 189 #endif 190 191 /* Assume that atomic operations are already serializing */ 192 #define smp_mb__before_atomic_dec() barrier() 193 #define smp_mb__after_atomic_dec() barrier() 194 #define smp_mb__before_atomic_inc() barrier() 195 #define smp_mb__after_atomic_inc() barrier() 196 197 #endif /* __KERNEL__ */ 198 #endif /* __ASM_GENERIC_ATOMIC_H */ 199