compat/compat_atomic.c

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

#if !((LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,31)) && (defined(CONFIG_UML) || defined(CONFIG_X86))) && !((LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,33)) && defined(CONFIG_ARM) && !defined(CONFIG_GENERIC_ATOMIC64))

static DEFINE_SPINLOCK(lock);

long long atomic64_read(const atomic64_t *v)
{
	unsigned long flags;
	long long val;

	spin_lock_irqsave(&lock, flags);
	val = v->counter;
	spin_unlock_irqrestore(&lock, flags);
	return val;
}
EXPORT_SYMBOL_GPL(atomic64_read);

void atomic64_set(atomic64_t *v, long long i)
{
	unsigned long flags;

	spin_lock_irqsave(&lock, flags);
	v->counter = i;
	spin_unlock_irqrestore(&lock, flags);
}
EXPORT_SYMBOL_GPL(atomic64_set);

long long atomic64_add_return(long long a, atomic64_t *v)
{
	unsigned long flags;
	long long val;

	spin_lock_irqsave(&lock, flags);
	val = v->counter += a;
	spin_unlock_irqrestore(&lock, flags);
	return val;
}
EXPORT_SYMBOL_GPL(atomic64_add_return);

#endif