1 #ifndef __ARCH_I386_ATOMIC__
2 #define __ARCH_I386_ATOMIC__
4 #include <linux/compiler.h>
5 #include <asm/processor.h>
8 * Atomic operations that C can't guarantee us. Useful for
9 * resource counting etc..
13 * Make sure gcc doesn't try to be clever and move things around
14 * on us. We need to use _exactly_ the address the user gave us,
15 * not some alias that contains the same information.
17 typedef struct { int counter
; } atomic_t
;
19 #define ATOMIC_INIT(i) { (i) }
22 * atomic_read - read atomic variable
23 * @v: pointer of type atomic_t
25 * Atomically reads the value of @v.
27 #define atomic_read(v) ((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 #define atomic_set(v,i) (((v)->counter) = (i))
39 * atomic_add - add integer to atomic variable
40 * @i: integer value to add
41 * @v: pointer of type atomic_t
43 * Atomically adds @i to @v.
45 static __inline__
void atomic_add(int i
, atomic_t
*v
)
48 LOCK_PREFIX
"addl %1,%0"
54 * atomic_sub - subtract the atomic variable
55 * @i: integer value to subtract
56 * @v: pointer of type atomic_t
58 * Atomically subtracts @i from @v.
60 static __inline__
void atomic_sub(int i
, atomic_t
*v
)
63 LOCK_PREFIX
"subl %1,%0"
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
73 * Atomically subtracts @i from @v and returns
74 * true if the result is zero, or false for all
77 static __inline__
int atomic_sub_and_test(int i
, atomic_t
*v
)
82 LOCK_PREFIX
"subl %2,%0; sete %1"
83 :"+m" (v
->counter
), "=qm" (c
)
84 :"ir" (i
) : "memory");
89 * atomic_inc - increment atomic variable
90 * @v: pointer of type atomic_t
92 * Atomically increments @v by 1.
94 static __inline__
void atomic_inc(atomic_t
*v
)
102 * atomic_dec - decrement atomic variable
103 * @v: pointer of type atomic_t
105 * Atomically decrements @v by 1.
107 static __inline__
void atomic_dec(atomic_t
*v
)
109 __asm__
__volatile__(
110 LOCK_PREFIX
"decl %0"
115 * atomic_dec_and_test - decrement and test
116 * @v: pointer of type atomic_t
118 * Atomically decrements @v by 1 and
119 * returns true if the result is 0, or false for all other
122 static __inline__
int atomic_dec_and_test(atomic_t
*v
)
126 __asm__
__volatile__(
127 LOCK_PREFIX
"decl %0; sete %1"
128 :"+m" (v
->counter
), "=qm" (c
)
134 * atomic_inc_and_test - increment and test
135 * @v: pointer of type atomic_t
137 * Atomically increments @v by 1
138 * and returns true if the result is zero, or false for all
141 static __inline__
int atomic_inc_and_test(atomic_t
*v
)
145 __asm__
__volatile__(
146 LOCK_PREFIX
"incl %0; sete %1"
147 :"+m" (v
->counter
), "=qm" (c
)
153 * atomic_add_negative - add and test if negative
154 * @v: pointer of type atomic_t
155 * @i: integer value to add
157 * Atomically adds @i to @v and returns true
158 * if the result is negative, or false when
159 * result is greater than or equal to zero.
161 static __inline__
int atomic_add_negative(int i
, atomic_t
*v
)
165 __asm__
__volatile__(
166 LOCK_PREFIX
"addl %2,%0; sets %1"
167 :"+m" (v
->counter
), "=qm" (c
)
168 :"ir" (i
) : "memory");
173 * atomic_add_return - add and return
174 * @v: pointer of type atomic_t
175 * @i: integer value to add
177 * Atomically adds @i to @v and returns @i + @v
179 static __inline__
int atomic_add_return(int i
, atomic_t
*v
)
184 if(unlikely(boot_cpu_data
.x86
==3))
187 /* Modern 486+ processor */
189 __asm__
__volatile__(
190 LOCK_PREFIX
"xaddl %0, %1"
191 :"+r" (i
), "+m" (v
->counter
)
196 no_xadd
: /* Legacy 386 processor */
197 local_irq_save(flags
);
198 __i
= atomic_read(v
);
199 atomic_set(v
, i
+ __i
);
200 local_irq_restore(flags
);
205 static __inline__
int atomic_sub_return(int i
, atomic_t
*v
)
207 return atomic_add_return(-i
,v
);
210 #define atomic_cmpxchg(v, old, new) ((int)cmpxchg(&((v)->counter), old, new))
211 #define atomic_xchg(v, new) (xchg(&((v)->counter), new))
214 * atomic_add_unless - add unless the number is already a given value
215 * @v: pointer of type atomic_t
216 * @a: the amount to add to v...
217 * @u: ...unless v is equal to u.
219 * Atomically adds @a to @v, so long as @v was not already @u.
220 * Returns non-zero if @v was not @u, and zero otherwise.
222 #define atomic_add_unless(v, a, u) \
225 c = atomic_read(v); \
227 if (unlikely(c == (u))) \
229 old = atomic_cmpxchg((v), c, c + (a)); \
230 if (likely(old == c)) \
236 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
238 #define atomic_inc_return(v) (atomic_add_return(1,v))
239 #define atomic_dec_return(v) (atomic_sub_return(1,v))
241 /* These are x86-specific, used by some header files */
242 #define atomic_clear_mask(mask, addr) \
243 __asm__ __volatile__(LOCK_PREFIX "andl %0,%1" \
244 : : "r" (~(mask)),"m" (*addr) : "memory")
246 #define atomic_set_mask(mask, addr) \
247 __asm__ __volatile__(LOCK_PREFIX "orl %0,%1" \
248 : : "r" (mask),"m" (*(addr)) : "memory")
250 /* Atomic operations are already serializing on x86 */
251 #define smp_mb__before_atomic_dec() barrier()
252 #define smp_mb__after_atomic_dec() barrier()
253 #define smp_mb__before_atomic_inc() barrier()
254 #define smp_mb__after_atomic_inc() barrier()
256 #include <asm-generic/atomic.h>