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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 | /* SPDX-License-Identifier: GPL-2.0-or-later */ /* * Generic C implementation of atomic counter operations. Usable on * UP systems only. Do not include in machine independent code. * * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) */ #ifndef __ASM_GENERIC_ATOMIC_H #define __ASM_GENERIC_ATOMIC_H #include <asm/cmpxchg.h> #include <asm/barrier.h> /* * atomic_$op() - $op integer to atomic variable * @i: integer value to $op * @v: pointer to the atomic variable * * Atomically $ops @i to @v. Does not strictly guarantee a memory-barrier, use * smp_mb__{before,after}_atomic(). */ /* * atomic_$op_return() - $op interer to atomic variable and returns the result * @i: integer value to $op * @v: pointer to the atomic variable * * Atomically $ops @i to @v. Does imply a full memory barrier. */ #ifdef CONFIG_SMP /* we can build all atomic primitives from cmpxchg */ #define ATOMIC_OP(op, c_op) \ static inline void atomic_##op(int i, atomic_t *v) \ { \ int c, old; \ \ c = v->counter; \ while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ c = old; \ } #define ATOMIC_OP_RETURN(op, c_op) \ static inline int atomic_##op##_return(int i, atomic_t *v) \ { \ int c, old; \ \ c = v->counter; \ while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ c = old; \ \ return c c_op i; \ } #define ATOMIC_FETCH_OP(op, c_op) \ static inline int atomic_fetch_##op(int i, atomic_t *v) \ { \ int c, old; \ \ c = v->counter; \ while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ c = old; \ \ return c; \ } #else #include <linux/irqflags.h> #define ATOMIC_OP(op, c_op) \ static inline void atomic_##op(int i, atomic_t *v) \ { \ unsigned long flags; \ \ raw_local_irq_save(flags); \ v->counter = v->counter c_op i; \ raw_local_irq_restore(flags); \ } #define ATOMIC_OP_RETURN(op, c_op) \ static inline int atomic_##op##_return(int i, atomic_t *v) \ { \ unsigned long flags; \ int ret; \ \ raw_local_irq_save(flags); \ ret = (v->counter = v->counter c_op i); \ raw_local_irq_restore(flags); \ \ return ret; \ } #define ATOMIC_FETCH_OP(op, c_op) \ static inline int atomic_fetch_##op(int i, atomic_t *v) \ { \ unsigned long flags; \ int ret; \ \ raw_local_irq_save(flags); \ ret = v->counter; \ v->counter = v->counter c_op i; \ raw_local_irq_restore(flags); \ \ return ret; \ } #endif /* CONFIG_SMP */ #ifndef atomic_add_return ATOMIC_OP_RETURN(add, +) #endif #ifndef atomic_sub_return ATOMIC_OP_RETURN(sub, -) #endif #ifndef atomic_fetch_add ATOMIC_FETCH_OP(add, +) #endif #ifndef atomic_fetch_sub ATOMIC_FETCH_OP(sub, -) #endif #ifndef atomic_fetch_and ATOMIC_FETCH_OP(and, &) #endif #ifndef atomic_fetch_or ATOMIC_FETCH_OP(or, |) #endif #ifndef atomic_fetch_xor ATOMIC_FETCH_OP(xor, ^) #endif #ifndef atomic_and ATOMIC_OP(and, &) #endif #ifndef atomic_or ATOMIC_OP(or, |) #endif #ifndef atomic_xor ATOMIC_OP(xor, ^) #endif #undef ATOMIC_FETCH_OP #undef ATOMIC_OP_RETURN #undef ATOMIC_OP /* * Atomic operations that C can't guarantee us. Useful for * resource counting etc.. */ #define ATOMIC_INIT(i) { (i) } /** * atomic_read - read atomic variable * @v: pointer of type atomic_t * * Atomically reads the value of @v. */ #ifndef atomic_read #define atomic_read(v) READ_ONCE((v)->counter) #endif /** * atomic_set - set atomic variable * @v: pointer of type atomic_t * @i: required value * * Atomically sets the value of @v to @i. */ #define atomic_set(v, i) WRITE_ONCE(((v)->counter), (i)) #include <linux/irqflags.h> static inline void atomic_add(int i, atomic_t *v) { atomic_add_return(i, v); } static inline void atomic_sub(int i, atomic_t *v) { atomic_sub_return(i, v); } #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) #endif /* __ASM_GENERIC_ATOMIC_H */ |