Quelle  atomic.h   Sprache: C

/* SPDX-License-Identifier: GPL-2.0-or-later */
/*
 * Generic C implementation of atomic counter operations. Do not include in
 * machine independent code.
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 */
#ifndef __ASM_GENERIC_ATOMIC_H
#define __ASM_GENERIC_ATOMIC_H

#include <asm/cmpxchg.h>
#include <asm/barrier.h>

#ifdef CONFIG_SMP

/* we can build all atomic primitives from cmpxchg */

#define ATOMIC_OP(op, c_op)      \
static inline void generic_atomic_##op(int i, atomic_t *v)  \
{         \
 int c, old;       \
         \
 c = v->counter;       \
 while ((old = arch_cmpxchg(&v->counter, c, c c_op i)) != c) \
  c = old;      \
}

#define ATOMIC_OP_RETURN(op, c_op)     \
static inline int generic_atomic_##op##_return(int i, atomic_t *v) \
{         \
 int c, old;       \
         \
 c = v->counter;       \
 while ((old = arch_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 generic_atomic_fetch_##op(int i, atomic_t *v)  \
{         \
 int c, old;       \
         \
 c = v->counter;       \
 while ((old = arch_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 generic_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 generic_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 generic_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 */

ATOMIC_OP_RETURN(add, +)
ATOMIC_OP_RETURN(sub, -)

ATOMIC_FETCH_OP(add, +)
ATOMIC_FETCH_OP(sub, -)
ATOMIC_FETCH_OP(and, &)
ATOMIC_FETCH_OP(or, |)
ATOMIC_FETCH_OP(xor, ^)

ATOMIC_OP(add, +)
ATOMIC_OP(sub, -)
ATOMIC_OP(and, &)
ATOMIC_OP(or, |)
ATOMIC_OP(xor, ^)

#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN
#undef ATOMIC_OP

#define arch_atomic_add_return   generic_atomic_add_return
#define arch_atomic_sub_return   generic_atomic_sub_return

#define arch_atomic_fetch_add   generic_atomic_fetch_add
#define arch_atomic_fetch_sub   generic_atomic_fetch_sub
#define arch_atomic_fetch_and   generic_atomic_fetch_and
#define arch_atomic_fetch_or   generic_atomic_fetch_or
#define arch_atomic_fetch_xor   generic_atomic_fetch_xor

#define arch_atomic_add    generic_atomic_add
#define arch_atomic_sub    generic_atomic_sub
#define arch_atomic_and    generic_atomic_and
#define arch_atomic_or    generic_atomic_or
#define arch_atomic_xor    generic_atomic_xor

#define arch_atomic_read(v)   READ_ONCE((v)->counter)
#define arch_atomic_set(v, i)   WRITE_ONCE(((v)->counter), (i))

#endif /* __ASM_GENERIC_ATOMIC_H */