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 #include <asm/barrier.h> 20 21 /* 22 * atomic_$op() - $op integer to atomic variable 23 * @i: integer value to $op 24 * @v: pointer to the atomic variable 25 * 26 * Atomically $ops @i to @v. Does not strictly guarantee a memory-barrier, use 27 * smp_mb__{before,after}_atomic(). 28 */ 29 30 /* 31 * atomic_$op_return() - $op interer to atomic variable and returns the result 32 * @i: integer value to $op 33 * @v: pointer to the atomic variable 34 * 35 * Atomically $ops @i to @v. Does imply a full memory barrier. 36 */ 37 38 #ifdef CONFIG_SMP 39 40 /* we can build all atomic primitives from cmpxchg */ 41 42 #define ATOMIC_OP(op, c_op) \ 43 static inline void atomic_##op(int i, atomic_t *v) \ 44 { \ 45 int c, old; \ 46 \ 47 c = v->counter; \ 48 while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ 49 c = old; \ 50 } 51 52 #define ATOMIC_OP_RETURN(op, c_op) \ 53 static inline int atomic_##op##_return(int i, atomic_t *v) \ 54 { \ 55 int c, old; \ 56 \ 57 c = v->counter; \ 58 while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ 59 c = old; \ 60 \ 61 return c c_op i; \ 62 } 63 64 #define ATOMIC_FETCH_OP(op, c_op) \ 65 static inline int atomic_fetch_##op(int i, atomic_t *v) \ 66 { \ 67 int c, old; \ 68 \ 69 c = v->counter; \ 70 while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ 71 c = old; \ 72 \ 73 return c; \ 74 } 75 76 #else 77 78 #include <linux/irqflags.h> 79 80 #define ATOMIC_OP(op, c_op) \ 81 static inline void atomic_##op(int i, atomic_t *v) \ 82 { \ 83 unsigned long flags; \ 84 \ 85 raw_local_irq_save(flags); \ 86 v->counter = v->counter c_op i; \ 87 raw_local_irq_restore(flags); \ 88 } 89 90 #define ATOMIC_OP_RETURN(op, c_op) \ 91 static inline int atomic_##op##_return(int i, atomic_t *v) \ 92 { \ 93 unsigned long flags; \ 94 int ret; \ 95 \ 96 raw_local_irq_save(flags); \ 97 ret = (v->counter = v->counter c_op i); \ 98 raw_local_irq_restore(flags); \ 99 \ 100 return ret; \ 101 } 102 103 #define ATOMIC_FETCH_OP(op, c_op) \ 104 static inline int atomic_fetch_##op(int i, atomic_t *v) \ 105 { \ 106 unsigned long flags; \ 107 int ret; \ 108 \ 109 raw_local_irq_save(flags); \ 110 ret = v->counter; \ 111 v->counter = v->counter c_op i; \ 112 raw_local_irq_restore(flags); \ 113 \ 114 return ret; \ 115 } 116 117 #endif /* CONFIG_SMP */ 118 119 #ifndef atomic_add_return 120 ATOMIC_OP_RETURN(add, +) 121 #endif 122 123 #ifndef atomic_sub_return 124 ATOMIC_OP_RETURN(sub, -) 125 #endif 126 127 #ifndef atomic_fetch_add 128 ATOMIC_FETCH_OP(add, +) 129 #endif 130 131 #ifndef atomic_fetch_sub 132 ATOMIC_FETCH_OP(sub, -) 133 #endif 134 135 #ifndef atomic_fetch_and 136 ATOMIC_FETCH_OP(and, &) 137 #endif 138 139 #ifndef atomic_fetch_or 140 ATOMIC_FETCH_OP(or, |) 141 #endif 142 143 #ifndef atomic_fetch_xor 144 ATOMIC_FETCH_OP(xor, ^) 145 #endif 146 147 #ifndef atomic_and 148 ATOMIC_OP(and, &) 149 #endif 150 151 #ifndef atomic_or 152 ATOMIC_OP(or, |) 153 #endif 154 155 #ifndef atomic_xor 156 ATOMIC_OP(xor, ^) 157 #endif 158 159 #undef ATOMIC_FETCH_OP 160 #undef ATOMIC_OP_RETURN 161 #undef ATOMIC_OP 162 163 /* 164 * Atomic operations that C can't guarantee us. Useful for 165 * resource counting etc.. 166 */ 167 168 #define ATOMIC_INIT(i) { (i) } 169 170 /** 171 * atomic_read - read atomic variable 172 * @v: pointer of type atomic_t 173 * 174 * Atomically reads the value of @v. 175 */ 176 #ifndef atomic_read 177 #define atomic_read(v) READ_ONCE((v)->counter) 178 #endif 179 180 /** 181 * atomic_set - set atomic variable 182 * @v: pointer of type atomic_t 183 * @i: required value 184 * 185 * Atomically sets the value of @v to @i. 186 */ 187 #define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i)) 188 189 #include <linux/irqflags.h> 190 191 static inline int atomic_add_negative(int i, atomic_t *v) 192 { 193 return atomic_add_return(i, v) < 0; 194 } 195 196 static inline void atomic_add(int i, atomic_t *v) 197 { 198 atomic_add_return(i, v); 199 } 200 201 static inline void atomic_sub(int i, atomic_t *v) 202 { 203 atomic_sub_return(i, v); 204 } 205 206 static inline void atomic_inc(atomic_t *v) 207 { 208 atomic_add_return(1, v); 209 } 210 211 static inline void atomic_dec(atomic_t *v) 212 { 213 atomic_sub_return(1, v); 214 } 215 216 #define atomic_dec_return(v) atomic_sub_return(1, (v)) 217 #define atomic_inc_return(v) atomic_add_return(1, (v)) 218 219 #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0) 220 #define atomic_dec_and_test(v) (atomic_dec_return(v) == 0) 221 #define atomic_inc_and_test(v) (atomic_inc_return(v) == 0) 222 223 #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) 224 #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) 225 226 #ifndef __atomic_add_unless 227 static inline int __atomic_add_unless(atomic_t *v, int a, int u) 228 { 229 int c, old; 230 c = atomic_read(v); 231 while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c) 232 c = old; 233 return c; 234 } 235 #endif 236 237 #endif /* __ASM_GENERIC_ATOMIC_H */ 238