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Brian Gerst5abbbbf2010-01-07 11:53:35 -05001#ifndef _ASM_X86_ATOMIC_H
2#define _ASM_X86_ATOMIC_H
3
4#include <linux/compiler.h>
5#include <linux/types.h>
6#include <asm/processor.h>
7#include <asm/alternative.h>
8#include <asm/cmpxchg.h>
9
10/*
11 * Atomic operations that C can't guarantee us. Useful for
12 * resource counting etc..
13 */
14
15#define ATOMIC_INIT(i) { (i) }
16
17/**
18 * atomic_read - read atomic variable
19 * @v: pointer of type atomic_t
20 *
21 * Atomically reads the value of @v.
22 */
23static inline int atomic_read(const atomic_t *v)
24{
Anton Blanchardf3d46f92010-05-17 14:33:53 +100025 return (*(volatile int *)&(v)->counter);
Brian Gerst5abbbbf2010-01-07 11:53:35 -050026}
27
28/**
29 * atomic_set - set atomic variable
30 * @v: pointer of type atomic_t
31 * @i: required value
32 *
33 * Atomically sets the value of @v to @i.
34 */
35static inline void atomic_set(atomic_t *v, int i)
36{
37 v->counter = i;
38}
39
40/**
41 * atomic_add - add integer to atomic variable
42 * @i: integer value to add
43 * @v: pointer of type atomic_t
44 *
45 * Atomically adds @i to @v.
46 */
47static inline void atomic_add(int i, atomic_t *v)
48{
49 asm volatile(LOCK_PREFIX "addl %1,%0"
50 : "+m" (v->counter)
51 : "ir" (i));
52}
53
54/**
55 * atomic_sub - subtract integer from atomic variable
56 * @i: integer value to subtract
57 * @v: pointer of type atomic_t
58 *
59 * Atomically subtracts @i from @v.
60 */
61static inline void atomic_sub(int i, atomic_t *v)
62{
63 asm volatile(LOCK_PREFIX "subl %1,%0"
64 : "+m" (v->counter)
65 : "ir" (i));
66}
67
68/**
69 * atomic_sub_and_test - subtract value from variable and test result
70 * @i: integer value to subtract
71 * @v: pointer of type atomic_t
72 *
73 * Atomically subtracts @i from @v and returns
74 * true if the result is zero, or false for all
75 * other cases.
76 */
77static inline int atomic_sub_and_test(int i, atomic_t *v)
78{
79 unsigned char c;
80
81 asm volatile(LOCK_PREFIX "subl %2,%0; sete %1"
82 : "+m" (v->counter), "=qm" (c)
83 : "ir" (i) : "memory");
84 return c;
85}
86
87/**
88 * atomic_inc - increment atomic variable
89 * @v: pointer of type atomic_t
90 *
91 * Atomically increments @v by 1.
92 */
93static inline void atomic_inc(atomic_t *v)
94{
95 asm volatile(LOCK_PREFIX "incl %0"
96 : "+m" (v->counter));
97}
98
99/**
100 * atomic_dec - decrement atomic variable
101 * @v: pointer of type atomic_t
102 *
103 * Atomically decrements @v by 1.
104 */
105static inline void atomic_dec(atomic_t *v)
106{
107 asm volatile(LOCK_PREFIX "decl %0"
108 : "+m" (v->counter));
109}
110
111/**
112 * atomic_dec_and_test - decrement and test
113 * @v: pointer of type atomic_t
114 *
115 * Atomically decrements @v by 1 and
116 * returns true if the result is 0, or false for all other
117 * cases.
118 */
119static inline int atomic_dec_and_test(atomic_t *v)
120{
121 unsigned char c;
122
123 asm volatile(LOCK_PREFIX "decl %0; sete %1"
124 : "+m" (v->counter), "=qm" (c)
125 : : "memory");
126 return c != 0;
127}
128
129/**
130 * atomic_inc_and_test - increment and test
131 * @v: pointer of type atomic_t
132 *
133 * Atomically increments @v by 1
134 * and returns true if the result is zero, or false for all
135 * other cases.
136 */
137static inline int atomic_inc_and_test(atomic_t *v)
138{
139 unsigned char c;
140
141 asm volatile(LOCK_PREFIX "incl %0; sete %1"
142 : "+m" (v->counter), "=qm" (c)
143 : : "memory");
144 return c != 0;
145}
146
147/**
148 * atomic_add_negative - add and test if negative
149 * @i: integer value to add
150 * @v: pointer of type atomic_t
151 *
152 * Atomically adds @i to @v and returns true
153 * if the result is negative, or false when
154 * result is greater than or equal to zero.
155 */
156static inline int atomic_add_negative(int i, atomic_t *v)
157{
158 unsigned char c;
159
160 asm volatile(LOCK_PREFIX "addl %2,%0; sets %1"
161 : "+m" (v->counter), "=qm" (c)
162 : "ir" (i) : "memory");
163 return c;
164}
165
166/**
167 * atomic_add_return - add integer and return
168 * @i: integer value to add
169 * @v: pointer of type atomic_t
170 *
171 * Atomically adds @i to @v and returns @i + @v
172 */
173static inline int atomic_add_return(int i, atomic_t *v)
174{
175 int __i;
176#ifdef CONFIG_M386
177 unsigned long flags;
178 if (unlikely(boot_cpu_data.x86 <= 3))
179 goto no_xadd;
Thomas Gleixner96a388d2007-10-11 11:20:03 +0200180#endif
Brian Gerst5abbbbf2010-01-07 11:53:35 -0500181 /* Modern 486+ processor */
182 __i = i;
183 asm volatile(LOCK_PREFIX "xaddl %0, %1"
184 : "+r" (i), "+m" (v->counter)
185 : : "memory");
186 return i + __i;
187
188#ifdef CONFIG_M386
189no_xadd: /* Legacy 386 processor */
Ingo Molnar17c0e712009-07-03 08:29:25 -0500190 raw_local_irq_save(flags);
Brian Gerst5abbbbf2010-01-07 11:53:35 -0500191 __i = atomic_read(v);
192 atomic_set(v, i + __i);
Ingo Molnar17c0e712009-07-03 08:29:25 -0500193 raw_local_irq_restore(flags);
Brian Gerst5abbbbf2010-01-07 11:53:35 -0500194 return i + __i;
195#endif
196}
197
198/**
199 * atomic_sub_return - subtract integer and return
200 * @v: pointer of type atomic_t
201 * @i: integer value to subtract
202 *
203 * Atomically subtracts @i from @v and returns @v - @i
204 */
205static inline int atomic_sub_return(int i, atomic_t *v)
206{
207 return atomic_add_return(-i, v);
208}
209
210#define atomic_inc_return(v) (atomic_add_return(1, v))
211#define atomic_dec_return(v) (atomic_sub_return(1, v))
212
213static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
214{
215 return cmpxchg(&v->counter, old, new);
216}
217
218static inline int atomic_xchg(atomic_t *v, int new)
219{
220 return xchg(&v->counter, new);
221}
222
223/**
224 * atomic_add_unless - add unless the number is already a given value
225 * @v: pointer of type atomic_t
226 * @a: the amount to add to v...
227 * @u: ...unless v is equal to u.
228 *
229 * Atomically adds @a to @v, so long as @v was not already @u.
230 * Returns non-zero if @v was not @u, and zero otherwise.
231 */
232static inline int atomic_add_unless(atomic_t *v, int a, int u)
233{
234 int c, old;
235 c = atomic_read(v);
236 for (;;) {
237 if (unlikely(c == (u)))
238 break;
239 old = atomic_cmpxchg((v), c, c + (a));
240 if (likely(old == c))
241 break;
242 c = old;
243 }
244 return c != (u);
245}
246
247#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
248
Luca Barbierid7f6de12010-02-26 12:22:41 +0100249/*
250 * atomic_dec_if_positive - decrement by 1 if old value positive
251 * @v: pointer of type atomic_t
252 *
253 * The function returns the old value of *v minus 1, even if
254 * the atomic variable, v, was not decremented.
255 */
256static inline int atomic_dec_if_positive(atomic_t *v)
257{
258 int c, old, dec;
259 c = atomic_read(v);
260 for (;;) {
261 dec = c - 1;
262 if (unlikely(dec < 0))
263 break;
264 old = atomic_cmpxchg((v), c, dec);
265 if (likely(old == c))
266 break;
267 c = old;
268 }
269 return dec;
270}
271
Brian Gerst5abbbbf2010-01-07 11:53:35 -0500272/**
273 * atomic_inc_short - increment of a short integer
274 * @v: pointer to type int
275 *
276 * Atomically adds 1 to @v
277 * Returns the new value of @u
278 */
279static inline short int atomic_inc_short(short int *v)
280{
281 asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
282 return *v;
283}
284
285#ifdef CONFIG_X86_64
286/**
287 * atomic_or_long - OR of two long integers
288 * @v1: pointer to type unsigned long
289 * @v2: pointer to type unsigned long
290 *
291 * Atomically ORs @v1 and @v2
292 * Returns the result of the OR
293 */
294static inline void atomic_or_long(unsigned long *v1, unsigned long v2)
295{
296 asm(LOCK_PREFIX "orq %1, %0" : "+m" (*v1) : "r" (v2));
297}
298#endif
299
300/* These are x86-specific, used by some header files */
301#define atomic_clear_mask(mask, addr) \
302 asm volatile(LOCK_PREFIX "andl %0,%1" \
303 : : "r" (~(mask)), "m" (*(addr)) : "memory")
304
305#define atomic_set_mask(mask, addr) \
306 asm volatile(LOCK_PREFIX "orl %0,%1" \
307 : : "r" ((unsigned)(mask)), "m" (*(addr)) \
308 : "memory")
309
310/* Atomic operations are already serializing on x86 */
311#define smp_mb__before_atomic_dec() barrier()
312#define smp_mb__after_atomic_dec() barrier()
313#define smp_mb__before_atomic_inc() barrier()
314#define smp_mb__after_atomic_inc() barrier()
315
316#ifdef CONFIG_X86_32
317# include "atomic64_32.h"
318#else
319# include "atomic64_64.h"
320#endif
321
322#include <asm-generic/atomic-long.h>
323#endif /* _ASM_X86_ATOMIC_H */