/* * 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. */ #define atomic_read(v) (*(volatile int *)&(v)->counter) /** * atomic_set - set atomic variable * @v: pointer of type atomic_t * @i: required value * * Atomically sets the value of @v to @i. */ #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 */ 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 */ 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 */