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Linux/arch/x86/include/asm/atomic.h

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  1 #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  */
 23 static inline int atomic_read(const atomic_t *v)
 24 {
 25         return (*(volatile int *)&(v)->counter);
 26 }
 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  */
 35 static 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  */
 47 static 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  */
 61 static 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  */
 77 static 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  */
 93 static 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  */
105 static 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  */
119 static 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  */
137 static 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  */
156 static 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  */
173 static inline int atomic_add_return(int i, atomic_t *v)
174 {
175         return i + xadd(&v->counter, i);
176 }
177 
178 /**
179  * atomic_sub_return - subtract integer and return
180  * @v: pointer of type atomic_t
181  * @i: integer value to subtract
182  *
183  * Atomically subtracts @i from @v and returns @v - @i
184  */
185 static inline int atomic_sub_return(int i, atomic_t *v)
186 {
187         return atomic_add_return(-i, v);
188 }
189 
190 #define atomic_inc_return(v)  (atomic_add_return(1, v))
191 #define atomic_dec_return(v)  (atomic_sub_return(1, v))
192 
193 static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
194 {
195         return cmpxchg(&v->counter, old, new);
196 }
197 
198 static inline int atomic_xchg(atomic_t *v, int new)
199 {
200         return xchg(&v->counter, new);
201 }
202 
203 /**
204  * __atomic_add_unless - add unless the number is already a given value
205  * @v: pointer of type atomic_t
206  * @a: the amount to add to v...
207  * @u: ...unless v is equal to u.
208  *
209  * Atomically adds @a to @v, so long as @v was not already @u.
210  * Returns the old value of @v.
211  */
212 static inline int __atomic_add_unless(atomic_t *v, int a, int u)
213 {
214         int c, old;
215         c = atomic_read(v);
216         for (;;) {
217                 if (unlikely(c == (u)))
218                         break;
219                 old = atomic_cmpxchg((v), c, c + (a));
220                 if (likely(old == c))
221                         break;
222                 c = old;
223         }
224         return c;
225 }
226 
227 /**
228  * atomic_inc_short - increment of a short integer
229  * @v: pointer to type int
230  *
231  * Atomically adds 1 to @v
232  * Returns the new value of @u
233  */
234 static inline short int atomic_inc_short(short int *v)
235 {
236         asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
237         return *v;
238 }
239 
240 #ifdef CONFIG_X86_64
241 /**
242  * atomic_or_long - OR of two long integers
243  * @v1: pointer to type unsigned long
244  * @v2: pointer to type unsigned long
245  *
246  * Atomically ORs @v1 and @v2
247  * Returns the result of the OR
248  */
249 static inline void atomic_or_long(unsigned long *v1, unsigned long v2)
250 {
251         asm(LOCK_PREFIX "orq %1, %0" : "+m" (*v1) : "r" (v2));
252 }
253 #endif
254 
255 /* These are x86-specific, used by some header files */
256 #define atomic_clear_mask(mask, addr)                           \
257         asm volatile(LOCK_PREFIX "andl %0,%1"                   \
258                      : : "r" (~(mask)), "m" (*(addr)) : "memory")
259 
260 #define atomic_set_mask(mask, addr)                             \
261         asm volatile(LOCK_PREFIX "orl %0,%1"                    \
262                      : : "r" ((unsigned)(mask)), "m" (*(addr))  \
263                      : "memory")
264 
265 /* Atomic operations are already serializing on x86 */
266 #define smp_mb__before_atomic_dec()     barrier()
267 #define smp_mb__after_atomic_dec()      barrier()
268 #define smp_mb__before_atomic_inc()     barrier()
269 #define smp_mb__after_atomic_inc()      barrier()
270 
271 #ifdef CONFIG_X86_32
272 # include <asm/atomic64_32.h>
273 #else
274 # include <asm/atomic64_64.h>
275 #endif
276 
277 #endif /* _ASM_X86_ATOMIC_H */
278 

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