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/alternative.h>
7 #include <asm/cmpxchg.h>
9 #include <asm/barrier.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 __always_inline int atomic_read(const atomic_t *v)
26 return READ_ONCE((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 __always_inline void atomic_set(atomic_t *v, int i)
38 WRITE_ONCE(v->counter, 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 __always_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 __always_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 __always_inline bool 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 __always_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 __always_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 __always_inline bool 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 __always_inline bool 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 __always_inline bool 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 __always_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 __always_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 __always_inline int atomic_fetch_add(int i, atomic_t *v)
176 return xadd(&v->counter, i);
179 static __always_inline int atomic_fetch_sub(int i, atomic_t *v)
181 return xadd(&v->counter, -i);
184 static __always_inline int atomic_cmpxchg(atomic_t *v, int old, int new)
186 return cmpxchg(&v->counter, old, new);
189 static inline int atomic_xchg(atomic_t *v, int new)
191 return xchg(&v->counter, new);
194 #define ATOMIC_OP(op) \
195 static inline void atomic_##op(int i, atomic_t *v) \
197 asm volatile(LOCK_PREFIX #op"l %1,%0" \
198 : "+m" (v->counter) \
203 #define ATOMIC_FETCH_OP(op, c_op) \
204 static inline int atomic_fetch_##op(int i, atomic_t *v) \
206 int old, val = atomic_read(v); \
208 old = atomic_cmpxchg(v, val, val c_op i); \
216 #define ATOMIC_OPS(op, c_op) \
218 ATOMIC_FETCH_OP(op, c_op)
225 #undef ATOMIC_FETCH_OP
229 * __atomic_add_unless - add unless the number is already a given value
230 * @v: pointer of type atomic_t
231 * @a: the amount to add to v...
232 * @u: ...unless v is equal to u.
234 * Atomically adds @a to @v, so long as @v was not already @u.
235 * Returns the old value of @v.
237 static __always_inline int __atomic_add_unless(atomic_t *v, int a, int u)
242 if (unlikely(c == (u)))
244 old = atomic_cmpxchg((v), c, c + (a));
245 if (likely(old == c))
253 * atomic_inc_short - increment of a short integer
254 * @v: pointer to type int
256 * Atomically adds 1 to @v
257 * Returns the new value of @u
259 static __always_inline short int atomic_inc_short(short int *v)
261 asm(LOCK_PREFIX "addw $1, %0" : "+m" (*v));
266 # include <asm/atomic64_32.h>
268 # include <asm/atomic64_64.h>
271 #endif /* _ASM_X86_ATOMIC_H */