/* * Generic C implementation of atomic counter operations. Usable on * UP systems only. Do not include in machine independent code. * * 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> /* * atomic_$op() - $op integer to atomic variable * @i: integer value to $op * @v: pointer to the atomic variable * * Atomically $ops @i to @v. Does not strictly guarantee a memory-barrier, use * smp_mb__{before,after}_atomic(). */ /* * atomic_$op_return() - $op interer to atomic variable and returns the result * @i: integer value to $op * @v: pointer to the atomic variable * * Atomically $ops @i to @v. Does imply a full memory barrier. */ #ifdef CONFIG_SMP /* we can build all atomic primitives from cmpxchg */ #define ATOMIC_OP(op, c_op) \ static inline void atomic_##op(int i, atomic_t *v) \ { \ int c, old; \ \ c = v->counter; \ while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ c = old; \ } #define ATOMIC_OP_RETURN(op, c_op) \ static inline int atomic_##op##_return(int i, atomic_t *v) \ { \ int c, old; \ \ c = v->counter; \ while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ c = old; \ \ return c c_op i; \ } #define ATOMIC_FETCH_OP(op, c_op) \ static inline int atomic_fetch_##op(int i, atomic_t *v) \ { \ int c, old; \ \ c = v->counter; \ while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ c = old; \ \ return c; \ } #else #include <linux/irqflags.h> #define ATOMIC_OP(op, c_op) \ static inline void atomic_##op(int i, atomic_t *v) \ { \ unsigned long flags; \ \ raw_local_irq_save(flags); \ v->counter = v->counter c_op i; \ raw_local_irq_restore(flags); \ } #define ATOMIC_OP_RETURN(op, c_op) \ static inline int atomic_##op##_return(int i, atomic_t *v) \ { \ unsigned long flags; \ int ret; \ \ raw_local_irq_save(flags); \ ret = (v->counter = v->counter c_op i); \ raw_local_irq_restore(flags); \ \ return ret; \ } #define ATOMIC_FETCH_OP(op, c_op) \ static inline int atomic_fetch_##op(int i, atomic_t *v) \ { \ unsigned long flags; \ int ret; \ \ raw_local_irq_save(flags); \ ret = v->counter; \ v->counter = v->counter c_op i; \ raw_local_irq_restore(flags); \ \ return ret; \ } #endif /* CONFIG_SMP */ #ifndef atomic_add_return ATOMIC_OP_RETURN(add, +) #endif #ifndef atomic_sub_return ATOMIC_OP_RETURN(sub, -) #endif #ifndef atomic_fetch_add ATOMIC_FETCH_OP(add, +) #endif #ifndef atomic_fetch_sub ATOMIC_FETCH_OP(sub, -) #endif #ifndef atomic_fetch_and ATOMIC_FETCH_OP(and, &) #endif #ifndef atomic_fetch_or ATOMIC_FETCH_OP(or, |) #endif #ifndef atomic_fetch_xor ATOMIC_FETCH_OP(xor, ^) #endif #ifndef atomic_and ATOMIC_OP(and, &) #endif #ifndef atomic_or ATOMIC_OP(or, |) #endif #ifndef atomic_xor ATOMIC_OP(xor, ^) #endif #undef ATOMIC_FETCH_OP #undef ATOMIC_OP_RETURN #undef ATOMIC_OP /* * Atomic operations that C can't guarantee us. Useful for * resource counting etc.. */ #define ATOMIC_INIT(i) { (i) } /** * atomic_read - read atomic variable * @v: pointer of type atomic_t * * Atomically reads the value of @v. */ #ifndef atomic_read #define atomic_read(v) READ_ONCE((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) WRITE_ONCE(((v)->counter), (i)) #include <linux/irqflags.h> 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); } #define atomic_xchg(ptr, v) (xchg(&(ptr)->counter, (v))) #define atomic_cmpxchg(v, old, new) (cmpxchg(&((v)->counter), (old), (new))) #endif /* __ASM_GENERIC_ATOMIC_H */