arch/sparc/lib/atomic32.c

Source file repositories/reference/linux-study-clean/arch/sparc/lib/atomic32.c

File Facts

System
Linux kernel
Corpus path
arch/sparc/lib/atomic32.c
Extension
.c
Size
4412 bytes
Lines
198
Domain
Architecture Layer
Bucket
arch/sparc
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
/*
 * atomic32.c: 32-bit atomic_t implementation
 *
 * Copyright (C) 2004 Keith M Wesolowski
 * Copyright (C) 2007 Kyle McMartin
 * 
 * Based on asm-parisc/atomic.h Copyright (C) 2000 Philipp Rumpf
 */

#include <linux/atomic.h>
#include <linux/spinlock.h>
#include <linux/module.h>

#ifdef CONFIG_SMP
#define ATOMIC_HASH_SIZE	4
#define ATOMIC_HASH(a)	(&__atomic_hash[(((unsigned long)a)>>8) & (ATOMIC_HASH_SIZE-1)])

spinlock_t __atomic_hash[ATOMIC_HASH_SIZE] = {
	[0 ... (ATOMIC_HASH_SIZE-1)] = __SPIN_LOCK_UNLOCKED(__atomic_hash)
};

#else /* SMP */

static DEFINE_SPINLOCK(dummy);
#define ATOMIC_HASH_SIZE	1
#define ATOMIC_HASH(a)		(&dummy)

#endif /* SMP */

#define ATOMIC_FETCH_OP(op, c_op)					\
int arch_atomic_fetch_##op(int i, atomic_t *v)				\
{									\
	int ret;							\
	unsigned long flags;						\
	spin_lock_irqsave(ATOMIC_HASH(v), flags);			\
									\
	ret = v->counter;						\
	v->counter c_op i;						\
									\
	spin_unlock_irqrestore(ATOMIC_HASH(v), flags);			\
	return ret;							\
}									\
EXPORT_SYMBOL(arch_atomic_fetch_##op);

#define ATOMIC_OP_RETURN(op, c_op)					\
int arch_atomic_##op##_return(int i, atomic_t *v)			\
{									\
	int ret;							\
	unsigned long flags;						\
	spin_lock_irqsave(ATOMIC_HASH(v), flags);			\
									\
	ret = (v->counter c_op i);					\
									\
	spin_unlock_irqrestore(ATOMIC_HASH(v), flags);			\
	return ret;							\
}									\
EXPORT_SYMBOL(arch_atomic_##op##_return);

ATOMIC_OP_RETURN(add, +=)

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

#undef ATOMIC_FETCH_OP
#undef ATOMIC_OP_RETURN

int arch_atomic_xchg(atomic_t *v, int new)
{
	int ret;
	unsigned long flags;

	spin_lock_irqsave(ATOMIC_HASH(v), flags);
	ret = v->counter;
	v->counter = new;
	spin_unlock_irqrestore(ATOMIC_HASH(v), flags);
	return ret;
}
EXPORT_SYMBOL(arch_atomic_xchg);

int arch_atomic_cmpxchg(atomic_t *v, int old, int new)
{
	int ret;
	unsigned long flags;

	spin_lock_irqsave(ATOMIC_HASH(v), flags);
	ret = v->counter;
	if (likely(ret == old))

Annotation

Implementation Notes