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Diffstat (limited to 'include/asm-generic/atomic.h')
| -rw-r--r-- | include/asm-generic/atomic.h | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/include/asm-generic/atomic.h b/include/asm-generic/atomic.h new file mode 100644 index 000000000000..c99c64dc5f3d --- /dev/null +++ b/include/asm-generic/atomic.h @@ -0,0 +1,165 @@ +/* + * Generic C implementation of atomic counter operations + * Originally implemented for MN10300. + * + * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ +#ifndef __ASM_GENERIC_ATOMIC_H +#define __ASM_GENERIC_ATOMIC_H + +#ifdef CONFIG_SMP +#error not SMP safe +#endif + +/* + * Atomic operations that C can't guarantee us. Useful for + * resource counting etc.. + */ + +#define ATOMIC_INIT(i) { (i) } + +#ifdef __KERNEL__ + +/** + * atomic_read - read atomic variable + * @v: pointer of type atomic_t + * + * Atomically reads the value of @v. Note that the guaranteed + * useful range of an atomic_t is only 24 bits. + */ +#define atomic_read(v) ((v)->counter) + +/** + * atomic_set - set atomic variable + * @v: pointer of type atomic_t + * @i: required value + * + * Atomically sets the value of @v to @i. Note that the guaranteed + * useful range of an atomic_t is only 24 bits. + */ +#define atomic_set(v, i) (((v)->counter) = (i)) + +#include <asm/system.h> + +/** + * atomic_add_return - add integer to atomic variable + * @i: integer value to add + * @v: pointer of type atomic_t + * + * Atomically adds @i to @v and returns the result + * Note that the guaranteed useful range of an atomic_t is only 24 bits. + */ +static inline int atomic_add_return(int i, atomic_t *v) +{ + unsigned long flags; + int temp; + + local_irq_save(flags); + temp = v->counter; + temp += i; + v->counter = temp; + local_irq_restore(flags); + + return temp; +} + +/** + * atomic_sub_return - subtract integer from atomic variable + * @i: integer value to subtract + * @v: pointer of type atomic_t + * + * Atomically subtracts @i from @v and returns the result + * Note that the guaranteed useful range of an atomic_t is only 24 bits. + */ +static inline int atomic_sub_return(int i, atomic_t *v) +{ + unsigned long flags; + int temp; + + local_irq_save(flags); + temp = v->counter; + temp -= i; + v->counter = temp; + local_irq_restore(flags); + + return temp; +} + +static inline int atomic_add_negative(int i, atomic_t *v) +{ + return atomic_add_return(i, v) < 0; +} + +static inline void atomic_add(int i, atomic_t *v) +{ + atomic_add_return(i, v); +} + +static inline void atomic_sub(int i, atomic_t *v) +{ + atomic_sub_return(i, v); +} + +static inline void atomic_inc(atomic_t *v) +{ + atomic_add_return(1, v); +} + +static inline void atomic_dec(atomic_t *v) +{ + atomic_sub_return(1, v); +} + +#define atomic_dec_return(v) atomic_sub_return(1, (v)) +#define atomic_inc_return(v) atomic_add_return(1, (v)) + +#define atomic_sub_and_test(i, v) (atomic_sub_return((i), (v)) == 0) +#define atomic_dec_and_test(v) (atomic_sub_return(1, (v)) == 0) +#define atomic_inc_and_test(v) (atomic_add_return(1, (v)) == 0) + +#define atomic_add_unless(v, a, u) \ +({ \ + int c, old; \ + c = atomic_read(v); \ + while (c != (u) && (old = atomic_cmpxchg((v), c, c + (a))) != c) \ + c = old; \ + c != (u); \ +}) + +#define atomic_inc_not_zero(v) atomic_add_unless((v), 1, 0) + +static inline void atomic_clear_mask(unsigned long mask, unsigned long *addr) +{ + unsigned long flags; + + mask = ~mask; + local_irq_save(flags); + *addr &= mask; + local_irq_restore(flags); +} + +#define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) +#define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) + +#define cmpxchg_local(ptr, o, n) \ + ((__typeof__(*(ptr)))__cmpxchg_local_generic((ptr), (unsigned long)(o),\ + (unsigned long)(n), sizeof(*(ptr)))) + +#define cmpxchg64_local(ptr, o, n) __cmpxchg64_local_generic((ptr), (o), (n)) + +/* Assume that atomic operations are already serializing */ +#define smp_mb__before_atomic_dec() barrier() +#define smp_mb__after_atomic_dec() barrier() +#define smp_mb__before_atomic_inc() barrier() +#define smp_mb__after_atomic_inc() barrier() + +#include <asm-generic/atomic-long.h> + +#endif /* __KERNEL__ */ +#endif /* __ASM_GENERIC_ATOMIC_H */ |