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1da177e4 LT |
1 | #ifndef __ARCH_I386_ATOMIC__ |
2 | #define __ARCH_I386_ATOMIC__ | |
3 | ||
4 | #include <linux/config.h> | |
5 | #include <linux/compiler.h> | |
6 | #include <asm/processor.h> | |
7 | ||
8 | /* | |
9 | * Atomic operations that C can't guarantee us. Useful for | |
10 | * resource counting etc.. | |
11 | */ | |
12 | ||
13 | #ifdef CONFIG_SMP | |
14 | #define LOCK "lock ; " | |
15 | #else | |
16 | #define LOCK "" | |
17 | #endif | |
18 | ||
19 | /* | |
20 | * Make sure gcc doesn't try to be clever and move things around | |
21 | * on us. We need to use _exactly_ the address the user gave us, | |
22 | * not some alias that contains the same information. | |
23 | */ | |
24 | typedef struct { volatile int counter; } atomic_t; | |
25 | ||
26 | #define ATOMIC_INIT(i) { (i) } | |
27 | ||
28 | /** | |
29 | * atomic_read - read atomic variable | |
30 | * @v: pointer of type atomic_t | |
31 | * | |
32 | * Atomically reads the value of @v. | |
33 | */ | |
34 | #define atomic_read(v) ((v)->counter) | |
35 | ||
36 | /** | |
37 | * atomic_set - set atomic variable | |
38 | * @v: pointer of type atomic_t | |
39 | * @i: required value | |
40 | * | |
41 | * Atomically sets the value of @v to @i. | |
42 | */ | |
43 | #define atomic_set(v,i) (((v)->counter) = (i)) | |
44 | ||
45 | /** | |
46 | * atomic_add - add integer to atomic variable | |
47 | * @i: integer value to add | |
48 | * @v: pointer of type atomic_t | |
49 | * | |
50 | * Atomically adds @i to @v. | |
51 | */ | |
52 | static __inline__ void atomic_add(int i, atomic_t *v) | |
53 | { | |
54 | __asm__ __volatile__( | |
55 | LOCK "addl %1,%0" | |
56 | :"=m" (v->counter) | |
57 | :"ir" (i), "m" (v->counter)); | |
58 | } | |
59 | ||
60 | /** | |
61 | * atomic_sub - subtract the atomic variable | |
62 | * @i: integer value to subtract | |
63 | * @v: pointer of type atomic_t | |
64 | * | |
65 | * Atomically subtracts @i from @v. | |
66 | */ | |
67 | static __inline__ void atomic_sub(int i, atomic_t *v) | |
68 | { | |
69 | __asm__ __volatile__( | |
70 | LOCK "subl %1,%0" | |
71 | :"=m" (v->counter) | |
72 | :"ir" (i), "m" (v->counter)); | |
73 | } | |
74 | ||
75 | /** | |
76 | * atomic_sub_and_test - subtract value from variable and test result | |
77 | * @i: integer value to subtract | |
78 | * @v: pointer of type atomic_t | |
79 | * | |
80 | * Atomically subtracts @i from @v and returns | |
81 | * true if the result is zero, or false for all | |
82 | * other cases. | |
83 | */ | |
84 | static __inline__ int atomic_sub_and_test(int i, atomic_t *v) | |
85 | { | |
86 | unsigned char c; | |
87 | ||
88 | __asm__ __volatile__( | |
89 | LOCK "subl %2,%0; sete %1" | |
90 | :"=m" (v->counter), "=qm" (c) | |
91 | :"ir" (i), "m" (v->counter) : "memory"); | |
92 | return c; | |
93 | } | |
94 | ||
95 | /** | |
96 | * atomic_inc - increment atomic variable | |
97 | * @v: pointer of type atomic_t | |
98 | * | |
99 | * Atomically increments @v by 1. | |
100 | */ | |
101 | static __inline__ void atomic_inc(atomic_t *v) | |
102 | { | |
103 | __asm__ __volatile__( | |
104 | LOCK "incl %0" | |
105 | :"=m" (v->counter) | |
106 | :"m" (v->counter)); | |
107 | } | |
108 | ||
109 | /** | |
110 | * atomic_dec - decrement atomic variable | |
111 | * @v: pointer of type atomic_t | |
112 | * | |
113 | * Atomically decrements @v by 1. | |
114 | */ | |
115 | static __inline__ void atomic_dec(atomic_t *v) | |
116 | { | |
117 | __asm__ __volatile__( | |
118 | LOCK "decl %0" | |
119 | :"=m" (v->counter) | |
120 | :"m" (v->counter)); | |
121 | } | |
122 | ||
123 | /** | |
124 | * atomic_dec_and_test - decrement and test | |
125 | * @v: pointer of type atomic_t | |
126 | * | |
127 | * Atomically decrements @v by 1 and | |
128 | * returns true if the result is 0, or false for all other | |
129 | * cases. | |
130 | */ | |
131 | static __inline__ int atomic_dec_and_test(atomic_t *v) | |
132 | { | |
133 | unsigned char c; | |
134 | ||
135 | __asm__ __volatile__( | |
136 | LOCK "decl %0; sete %1" | |
137 | :"=m" (v->counter), "=qm" (c) | |
138 | :"m" (v->counter) : "memory"); | |
139 | return c != 0; | |
140 | } | |
141 | ||
142 | /** | |
143 | * atomic_inc_and_test - increment and test | |
144 | * @v: pointer of type atomic_t | |
145 | * | |
146 | * Atomically increments @v by 1 | |
147 | * and returns true if the result is zero, or false for all | |
148 | * other cases. | |
149 | */ | |
150 | static __inline__ int atomic_inc_and_test(atomic_t *v) | |
151 | { | |
152 | unsigned char c; | |
153 | ||
154 | __asm__ __volatile__( | |
155 | LOCK "incl %0; sete %1" | |
156 | :"=m" (v->counter), "=qm" (c) | |
157 | :"m" (v->counter) : "memory"); | |
158 | return c != 0; | |
159 | } | |
160 | ||
161 | /** | |
162 | * atomic_add_negative - add and test if negative | |
163 | * @v: pointer of type atomic_t | |
164 | * @i: integer value to add | |
165 | * | |
166 | * Atomically adds @i to @v and returns true | |
167 | * if the result is negative, or false when | |
168 | * result is greater than or equal to zero. | |
169 | */ | |
170 | static __inline__ int atomic_add_negative(int i, atomic_t *v) | |
171 | { | |
172 | unsigned char c; | |
173 | ||
174 | __asm__ __volatile__( | |
175 | LOCK "addl %2,%0; sets %1" | |
176 | :"=m" (v->counter), "=qm" (c) | |
177 | :"ir" (i), "m" (v->counter) : "memory"); | |
178 | return c; | |
179 | } | |
180 | ||
181 | /** | |
182 | * atomic_add_return - add and return | |
183 | * @v: pointer of type atomic_t | |
184 | * @i: integer value to add | |
185 | * | |
186 | * Atomically adds @i to @v and returns @i + @v | |
187 | */ | |
188 | static __inline__ int atomic_add_return(int i, atomic_t *v) | |
189 | { | |
190 | int __i; | |
191 | #ifdef CONFIG_M386 | |
192 | if(unlikely(boot_cpu_data.x86==3)) | |
193 | goto no_xadd; | |
194 | #endif | |
195 | /* Modern 486+ processor */ | |
196 | __i = i; | |
197 | __asm__ __volatile__( | |
198 | LOCK "xaddl %0, %1;" | |
199 | :"=r"(i) | |
200 | :"m"(v->counter), "0"(i)); | |
201 | return i + __i; | |
202 | ||
203 | #ifdef CONFIG_M386 | |
204 | no_xadd: /* Legacy 386 processor */ | |
205 | local_irq_disable(); | |
206 | __i = atomic_read(v); | |
207 | atomic_set(v, i + __i); | |
208 | local_irq_enable(); | |
209 | return i + __i; | |
210 | #endif | |
211 | } | |
212 | ||
213 | static __inline__ int atomic_sub_return(int i, atomic_t *v) | |
214 | { | |
215 | return atomic_add_return(-i,v); | |
216 | } | |
217 | ||
218 | #define atomic_inc_return(v) (atomic_add_return(1,v)) | |
219 | #define atomic_dec_return(v) (atomic_sub_return(1,v)) | |
220 | ||
221 | /* These are x86-specific, used by some header files */ | |
222 | #define atomic_clear_mask(mask, addr) \ | |
223 | __asm__ __volatile__(LOCK "andl %0,%1" \ | |
224 | : : "r" (~(mask)),"m" (*addr) : "memory") | |
225 | ||
226 | #define atomic_set_mask(mask, addr) \ | |
227 | __asm__ __volatile__(LOCK "orl %0,%1" \ | |
228 | : : "r" (mask),"m" (*(addr)) : "memory") | |
229 | ||
230 | /* Atomic operations are already serializing on x86 */ | |
231 | #define smp_mb__before_atomic_dec() barrier() | |
232 | #define smp_mb__after_atomic_dec() barrier() | |
233 | #define smp_mb__before_atomic_inc() barrier() | |
234 | #define smp_mb__after_atomic_inc() barrier() | |
235 | ||
236 | #endif |