1 #ifndef _ASM_X86_ATOMIC_H
2 #define _ASM_X86_ATOMIC_H
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>
12 * Atomic operations that C can't guarantee us. Useful for
13 * resource counting etc..
16 #define ATOMIC_INIT(i) { (i) }
19 * atomic_read - read atomic variable
20 * @v: pointer of type atomic_t
22 * Atomically reads the value of @v.
24 static inline int atomic_read(const atomic_t *v)
26 return (*(volatile int *)&(v)->counter);
30 * atomic_set - set atomic variable
31 * @v: pointer of type atomic_t
34 * Atomically sets the value of @v to @i.
36 static inline void atomic_set(atomic_t *v, int i)
42 * atomic_add - add integer to atomic variable
43 * @i: integer value to add
44 * @v: pointer of type atomic_t
46 * Atomically adds @i to @v.
48 static inline void atomic_add(int i, atomic_t *v)
50 asm volatile(LOCK_PREFIX "addl %1,%0"
56 * atomic_sub - subtract integer from atomic variable
57 * @i: integer value to subtract
58 * @v: pointer of type atomic_t
60 * Atomically subtracts @i from @v.
62 static inline void atomic_sub(int i, atomic_t *v)
64 asm volatile(LOCK_PREFIX "subl %1,%0"
70 * atomic_sub_and_test - subtract value from variable and test result
71 * @i: integer value to subtract
72 * @v: pointer of type atomic_t
74 * Atomically subtracts @i from @v and returns
75 * true if the result is zero, or false for all
78 static inline int atomic_sub_and_test(int i, atomic_t *v)
80 GEN_BINARY_RMWcc(LOCK_PREFIX "subl", v->counter, "er", i, "%0", "e");
84 * atomic_inc - increment atomic variable
85 * @v: pointer of type atomic_t
87 * Atomically increments @v by 1.
89 static inline void atomic_inc(atomic_t *v)
91 asm volatile(LOCK_PREFIX "incl %0"
96 * atomic_dec - decrement atomic variable
97 * @v: pointer of type atomic_t
99 * Atomically decrements @v by 1.
101 static inline void atomic_dec(atomic_t *v)
103 asm volatile(LOCK_PREFIX "decl %0"
104 : "+m" (v->counter));
108 * atomic_dec_and_test - decrement and test
109 * @v: pointer of type atomic_t
111 * Atomically decrements @v by 1 and
112 * returns true if the result is 0, or false for all other
115 static inline int atomic_dec_and_test(atomic_t *v)
117 GEN_UNARY_RMWcc(LOCK_PREFIX "decl", v->counter, "%0", "e");
121 * atomic_inc_and_test - increment and test
122 * @v: pointer of type atomic_t
124 * Atomically increments @v by 1
125 * and returns true if the result is zero, or false for all
128 static inline int atomic_inc_and_test(atomic_t *v)
130 GEN_UNARY_RMWcc(LOCK_PREFIX "incl", v->counter, "%0", "e");
134 * atomic_add_negative - add and test if negative
135 * @i: integer value to add
136 * @v: pointer of type atomic_t
138 * Atomically adds @i to @v and returns true
139 * if the result is negative, or false when
140 * result is greater than or equal to zero.
142 static inline int atomic_add_negative(int i, atomic_t *v)
144 GEN_BINARY_RMWcc(LOCK_PREFIX "addl", v->counter, "er", i, "%0", "s");
148 * atomic_add_return - add integer and return
149 * @i: integer value to add
150 * @v: pointer of type atomic_t
152 * Atomically adds @i to @v and returns @i + @v
154 static inline int atomic_add_return(int i, atomic_t *v)
156 return i + xadd(&v->counter, i);
160 * atomic_sub_return - subtract integer and return
161 * @v: pointer of type atomic_t
162 * @i: integer value to subtract
164 * Atomically subtracts @i from @v and returns @v - @i
166 static inline int atomic_sub_return(int i, atomic_t *v)
168 return atomic_add_return(-i, v);
171 #define atomic_inc_return(v) (atomic_add_return(1, v))
172 #define atomic_dec_return(v) (atomic_sub_return(1, v))
174 static inline int atomic_cmpxchg(atomic_t *v, int old, int new)
176 return cmpxchg(&v->counter, old, new);
179 static inline int atomic_xchg(atomic_t *v, int new)
181 return xchg(&v->counter, new);
185 * __atomic_add_unless - add unless the number is already a given value
186 * @v: pointer of type atomic_t
187 * @a: the amount to add to v...
188 * @u: ...unless v is equal to u.
190 * Atomically adds @a to @v, so long as @v was not already @u.
191 * Returns the old value of @v.
193 static inline int __atomic_add_unless(atomic_t *v, int a, int u)
198 if (unlikely(c == (u)))
200 old = atomic_cmpxchg((v), c, c + (a));
201 if (likely(old == c))
209 * atomic_inc_short - increment of a short integer
210 * @v: pointer to type int
212 * Atomically adds 1 to @v
213 * Returns the new value of @u
215 static inline short int atomic_inc_short(short int *v)
217 asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
223 * atomic_or_long - OR of two long integers
224 * @v1: pointer to type unsigned long
225 * @v2: pointer to type unsigned long
227 * Atomically ORs @v1 and @v2
228 * Returns the result of the OR
230 static inline void atomic_or_long(unsigned long *v1, unsigned long v2)
232 asm(LOCK_PREFIX "orq %1, %0" : "+m" (*v1) : "r" (v2));
236 /* These are x86-specific, used by some header files */
237 #define atomic_clear_mask(mask, addr) \
238 asm volatile(LOCK_PREFIX "andl %0,%1" \
239 : : "r" (~(mask)), "m" (*(addr)) : "memory")
241 #define atomic_set_mask(mask, addr) \
242 asm volatile(LOCK_PREFIX "orl %0,%1" \
243 : : "r" ((unsigned)(mask)), "m" (*(addr)) \
246 /* Atomic operations are already serializing on x86 */
247 #define smp_mb__before_atomic_dec() barrier()
248 #define smp_mb__after_atomic_dec() barrier()
249 #define smp_mb__before_atomic_inc() barrier()
250 #define smp_mb__after_atomic_inc() barrier()
253 # include <asm/atomic64_32.h>
255 # include <asm/atomic64_64.h>
258 #endif /* _ASM_X86_ATOMIC_H */