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
atomic_add_negative(int i,atomic_t * v)191 static inline int atomic_add_negative(int i, atomic_t *v)
192 {
193 return atomic_add_return(i, v) < 0;
194 }
195
atomic_add(int i,atomic_t * v)196 static inline void atomic_add(int i, atomic_t *v)
197 {
198 atomic_add_return(i, v);
199 }
200
atomic_sub(int i,atomic_t * v)201 static inline void atomic_sub(int i, atomic_t *v)
202 {
203 atomic_sub_return(i, v);
204 }
205
atomic_inc(atomic_t * v)206 static inline void atomic_inc(atomic_t *v)
207 {
208 atomic_add_return(1, v);
209 }
210
atomic_dec(atomic_t * v)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
__atomic_add_unless(atomic_t * v,int a,int u)226 static inline int __atomic_add_unless(atomic_t *v, int a, int u)
227 {
228 int c, old;
229 c = atomic_read(v);
230 while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c)
231 c = old;
232 return c;
233 }
234
235 #endif /* __ASM_GENERIC_ATOMIC_H */
236