2 * Generic C implementation of atomic counter operations
3 * Originally implemented for MN10300.
5 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
6 * Written by David Howells (dhowells@redhat.com)
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public Licence
10 * as published by the Free Software Foundation; either version
11 * 2 of the Licence, or (at your option) any later version.
13 #ifndef __ASM_GENERIC_ATOMIC_H
14 #define __ASM_GENERIC_ATOMIC_H
21 * Atomic operations that C can't guarantee us. Useful for
22 * resource counting etc..
25 #define ATOMIC_INIT(i) { (i) }
30 * atomic_read - read atomic variable
31 * @v: pointer of type atomic_t
33 * Atomically reads the value of @v. Note that the guaranteed
34 * useful range of an atomic_t is only 24 bits.
36 #define atomic_read(v) ((v)->counter)
39 * atomic_set - set atomic variable
40 * @v: pointer of type atomic_t
43 * Atomically sets the value of @v to @i. Note that the guaranteed
44 * useful range of an atomic_t is only 24 bits.
46 #define atomic_set(v, i) (((v)->counter) = (i))
48 #include <asm/system.h>
51 * atomic_add_return - add integer to atomic variable
52 * @i: integer value to add
53 * @v: pointer of type atomic_t
55 * Atomically adds @i to @v and returns the result
56 * Note that the guaranteed useful range of an atomic_t is only 24 bits.
58 static inline int atomic_add_return(int i
, atomic_t
*v
)
63 local_irq_save(flags
);
67 local_irq_restore(flags
);
73 * atomic_sub_return - subtract integer from atomic variable
74 * @i: integer value to subtract
75 * @v: pointer of type atomic_t
77 * Atomically subtracts @i from @v and returns the result
78 * Note that the guaranteed useful range of an atomic_t is only 24 bits.
80 static inline int atomic_sub_return(int i
, atomic_t
*v
)
85 local_irq_save(flags
);
89 local_irq_restore(flags
);
94 static inline int atomic_add_negative(int i
, atomic_t
*v
)
96 return atomic_add_return(i
, v
) < 0;
99 static inline void atomic_add(int i
, atomic_t
*v
)
101 atomic_add_return(i
, v
);
104 static inline void atomic_sub(int i
, atomic_t
*v
)
106 atomic_sub_return(i
, v
);
109 static inline void atomic_inc(atomic_t
*v
)
111 atomic_add_return(1, v
);
114 static inline void atomic_dec(atomic_t
*v
)
116 atomic_sub_return(1, v
);
119 #define atomic_dec_return(v) atomic_sub_return(1, (v))
120 #define atomic_inc_return(v) atomic_add_return(1, (v))
122 #define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0)
123 #define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0)
124 #define atomic_inc_and_test(v) (atomic_add_return(1, (v)) == 0)
126 #define atomic_add_unless(v, a, u) \
129 c = atomic_read(v); \
130 while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \
135 #define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0)
137 static inline void atomic_clear_mask(unsigned long mask
, unsigned long *addr
)
142 local_irq_save(flags
);
144 local_irq_restore(flags
);
147 #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v)))
148 #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new)))
150 #define cmpxchg_local(ptr, o, n) \
151 ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\
152 (unsigned long)(n), sizeof(*(ptr))))
154 #define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n))
156 /* Assume that atomic operations are already serializing */
157 #define smp_mb__before_atomic_dec() barrier()
158 #define smp_mb__after_atomic_dec() barrier()
159 #define smp_mb__before_atomic_inc() barrier()
160 #define smp_mb__after_atomic_inc() barrier()
162 #include <asm-generic/atomic-long.h>
164 #endif /* __KERNEL__ */
165 #endif /* __ASM_GENERIC_ATOMIC_H */
This page took 0.032964 seconds and 5 git commands to generate.