1 #ifndef _ASM_X86_ATOMIC_32_H
2 #define _ASM_X86_ATOMIC_32_H
3
4 #include <linux/compiler.h>
5 #include <linux/types.h>
6 #include <asm/processor.h>
7 #include <asm/cmpxchg.h>
8
9 /*
10 * Atomic operations that C can't guarantee us. Useful for
11 * resource counting etc..
12 */
13
14 #define ATOMIC_INIT(i) { (i) }
15
16 /**
17 * atomic_read - read atomic variable
18 * @v: pointer of type atomic_t
19 *
20 * Atomically reads the value of @v.
21 */
22 #define atomic_read(v) ((v)->counter)
23
24 /**
25 * atomic_set - set atomic variable
26 * @v: pointer of type atomic_t
27 * @i: required value
28 *
29 * Atomically sets the value of @v to @i.
30 */
31 #define atomic_set(v, i) (((v)->counter) = (i))
32
33 /**
34 * atomic_add - add integer to atomic variable
35 * @i: integer value to add
36 * @v: pointer of type atomic_t
37 *
38 * Atomically adds @i to @v.
39 */
atomic_add(int i,atomic_t * v)40 static inline void atomic_add(int i, atomic_t *v)
41 {
42 asm volatile(LOCK_PREFIX "addl %1,%0"
43 : "+m" (v->counter)
44 : "ir" (i));
45 }
46
47 /**
48 * atomic_sub - subtract integer from atomic variable
49 * @i: integer value to subtract
50 * @v: pointer of type atomic_t
51 *
52 * Atomically subtracts @i from @v.
53 */
atomic_sub(int i,atomic_t * v)54 static inline void atomic_sub(int i, atomic_t *v)
55 {
56 asm volatile(LOCK_PREFIX "subl %1,%0"
57 : "+m" (v->counter)
58 : "ir" (i));
59 }
60
61 /**
62 * atomic_sub_and_test - subtract value from variable and test result
63 * @i: integer value to subtract
64 * @v: pointer of type atomic_t
65 *
66 * Atomically subtracts @i from @v and returns
67 * true if the result is zero, or false for all
68 * other cases.
69 */
atomic_sub_and_test(int i,atomic_t * v)70 static inline int atomic_sub_and_test(int i, atomic_t *v)
71 {
72 unsigned char c;
73
74 asm volatile(LOCK_PREFIX "subl %2,%0; sete %1"
75 : "+m" (v->counter), "=qm" (c)
76 : "ir" (i) : "memory");
77 return c;
78 }
79
80 /**
81 * atomic_inc - increment atomic variable
82 * @v: pointer of type atomic_t
83 *
84 * Atomically increments @v by 1.
85 */
atomic_inc(atomic_t * v)86 static inline void atomic_inc(atomic_t *v)
87 {
88 asm volatile(LOCK_PREFIX "incl %0"
89 : "+m" (v->counter));
90 }
91
92 /**
93 * atomic_dec - decrement atomic variable
94 * @v: pointer of type atomic_t
95 *
96 * Atomically decrements @v by 1.
97 */
atomic_dec(atomic_t * v)98 static inline void atomic_dec(atomic_t *v)
99 {
100 asm volatile(LOCK_PREFIX "decl %0"
101 : "+m" (v->counter));
102 }
103
104 /**
105 * atomic_dec_and_test - decrement and test
106 * @v: pointer of type atomic_t
107 *
108 * Atomically decrements @v by 1 and
109 * returns true if the result is 0, or false for all other
110 * cases.
111 */
atomic_dec_and_test(atomic_t * v)112 static inline int atomic_dec_and_test(atomic_t *v)
113 {
114 unsigned char c;
115
116 asm volatile(LOCK_PREFIX "decl %0; sete %1"
117 : "+m" (v->counter), "=qm" (c)
118 : : "memory");
119 return c != 0;
120 }
121
122 /**
123 * atomic_inc_and_test - increment and test
124 * @v: pointer of type atomic_t
125 *
126 * Atomically increments @v by 1
127 * and returns true if the result is zero, or false for all
128 * other cases.
129 */
atomic_inc_and_test(atomic_t * v)130 static inline int atomic_inc_and_test(atomic_t *v)
131 {
132 unsigned char c;
133
134 asm volatile(LOCK_PREFIX "incl %0; sete %1"
135 : "+m" (v->counter), "=qm" (c)
136 : : "memory");
137 return c != 0;
138 }
139
140 /**
141 * atomic_add_negative - add and test if negative
142 * @v: pointer of type atomic_t
143 * @i: integer value to add
144 *
145 * Atomically adds @i to @v and returns true
146 * if the result is negative, or false when
147 * result is greater than or equal to zero.
148 */
atomic_add_negative(int i,atomic_t * v)149 static inline int atomic_add_negative(int i, atomic_t *v)
150 {
151 unsigned char c;
152
153 asm volatile(LOCK_PREFIX "addl %2,%0; sets %1"
154 : "+m" (v->counter), "=qm" (c)
155 : "ir" (i) : "memory");
156 return c;
157 }
158
159 /**
160 * atomic_add_return - add integer and return
161 * @v: pointer of type atomic_t
162 * @i: integer value to add
163 *
164 * Atomically adds @i to @v and returns @i + @v
165 */
atomic_add_return(int i,atomic_t * v)166 static inline int atomic_add_return(int i, atomic_t *v)
167 {
168 int __i;
169 #ifdef CONFIG_M386
170 unsigned long flags;
171 if (unlikely(boot_cpu_data.x86 <= 3))
172 goto no_xadd;
173 #endif
174 /* Modern 486+ processor */
175 __i = i;
176 asm volatile(LOCK_PREFIX "xaddl %0, %1"
177 : "+r" (i), "+m" (v->counter)
178 : : "memory");
179 return i + __i;
180
181 #ifdef CONFIG_M386
182 no_xadd: /* Legacy 386 processor */
183 local_irq_save(flags);
184 __i = atomic_read(v);
185 atomic_set(v, i + __i);
186 local_irq_restore(flags);
187 return i + __i;
188 #endif
189 }
190
191 /**
192 * atomic_sub_return - subtract integer and return
193 * @v: pointer of type atomic_t
194 * @i: integer value to subtract
195 *
196 * Atomically subtracts @i from @v and returns @v - @i
197 */
atomic_sub_return(int i,atomic_t * v)198 static inline int atomic_sub_return(int i, atomic_t *v)
199 {
200 return atomic_add_return(-i, v);
201 }
202
203 #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
204 #define atomic_xchg(v, new) (xchg(&((v)->counter), (new)))
205
206 /**
207 * atomic_add_unless - add unless the number is already a given value
208 * @v: pointer of type atomic_t
209 * @a: the amount to add to v...
210 * @u: ...unless v is equal to u.
211 *
212 * Atomically adds @a to @v, so long as @v was not already @u.
213 * Returns non-zero if @v was not @u, and zero otherwise.
214 */
atomic_add_unless(atomic_t * v,int a,int u)215 static inline int atomic_add_unless(atomic_t *v, int a, int u)
216 {
217 int c, old;
218 c = atomic_read(v);
219 for (;;) {
220 if (unlikely(c == (u)))
221 break;
222 old = atomic_cmpxchg((v), c, c + (a));
223 if (likely(old == c))
224 break;
225 c = old;
226 }
227 return c != (u);
228 }
229
230 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
231
232 #define atomic_inc_return(v) (atomic_add_return(1, v))
233 #define atomic_dec_return(v) (atomic_sub_return(1, v))
234
235 /* These are x86-specific, used by some header files */
236 #define atomic_clear_mask(mask, addr) \
237 asm volatile(LOCK_PREFIX "andl %0,%1" \
238 : : "r" (~(mask)), "m" (*(addr)) : "memory")
239
240 #define atomic_set_mask(mask, addr) \
241 asm volatile(LOCK_PREFIX "orl %0,%1" \
242 : : "r" (mask), "m" (*(addr)) : "memory")
243
244 /* Atomic operations are already serializing on x86 */
245 #define smp_mb__before_atomic_dec() barrier()
246 #define smp_mb__after_atomic_dec() barrier()
247 #define smp_mb__before_atomic_inc() barrier()
248 #define smp_mb__after_atomic_inc() barrier()
249
250 #include <asm-generic/atomic.h>
251 #endif /* _ASM_X86_ATOMIC_32_H */
252