/* * Generic C implementation of atomic counter operations. Usable on * UP systems only. Do not include in machine independent code. * * 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 #include <asm/cmpxchg.h> #include <asm/barrier.h> #ifdef CONFIG_SMP /* Force people to define core atomics */ # if !defined(atomic_add_return) || !defined(atomic_sub_return) || \ !defined(atomic_clear_mask) || !defined(atomic_set_mask) # error "SMP requires a little arch-specific magic" # endif #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. */ #ifndef atomic_read #define atomic_read(v) (*(volatile int *)&(v)->counter) #endif /** * 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 <linux/irqflags.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 */ #ifndef atomic_add_return static inline int atomic_add_return(int i, atomic_t *v) { unsigned long flags; int temp; raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */ temp = v->counter; temp += i; v->counter = temp; raw_local_irq_restore(flags); return temp; } #endif /** * 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 */ #ifndef atomic_sub_return static inline int atomic_sub_return(int i, atomic_t *v) { unsigned long flags; int temp; raw_local_irq_save(flags); /* Don't trace it in an irqsoff handler */ temp = v->counter; temp -= i; v->counter = temp; raw_local_irq_restore(flags); return temp; } #endif 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_dec_return(v) == 0) #define atomic_inc_and_test(v) (atomic_inc_return(v) == 0) #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) static inline int __atomic_add_unless(atomic_t *v, int a, int u) { int c, old; c = atomic_read(v); while (c != u && (old = atomic_cmpxchg(v, c, c + a)) != c) c = old; return c; } /** * atomic_clear_mask - Atomically clear bits in atomic variable * @mask: Mask of the bits to be cleared * @v: pointer of type atomic_t * * Atomically clears the bits set in @mask from @v */ #ifndef atomic_clear_mask static inline void atomic_clear_mask(unsigned long mask, atomic_t *v) { unsigned long flags; mask = ~mask; raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ v->counter &= mask; raw_local_irq_restore(flags); } #endif /** * atomic_set_mask - Atomically set bits in atomic variable * @mask: Mask of the bits to be set * @v: pointer of type atomic_t * * Atomically sets the bits set in @mask in @v */ #ifndef atomic_set_mask static inline void atomic_set_mask(unsigned int mask, atomic_t *v) { unsigned long flags; raw_local_irq_save(flags); /* Don't trace it in a irqsoff handler */ v->counter |= mask; raw_local_irq_restore(flags); } #endif #endif /* __KERNEL__ */ #endif /* __ASM_GENERIC_ATOMIC_H */