include/linux/bit_spinlock.h

#ifndef __LINUX_BIT_SPINLOCK_H
#define __LINUX_BIT_SPINLOCK_H

#include <linux/kernel.h>
#include <linux/preempt.h>
#include <linux/atomic.h>
#include <linux/bug.h>

static inline void bit_spin_lock(int bitnum, unsigned long *addr)
{
	preempt_disable();
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
	while (unlikely(test_and_set_bit_lock(bitnum, addr))) {
		preempt_enable();
		do {
			cpu_relax();
		} while (test_bit(bitnum, addr));
		preempt_disable();
	}
#endif
	__acquire(bitlock);
}

static inline int bit_spin_trylock(int bitnum, unsigned long *addr)
{
	preempt_disable();
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
	if (unlikely(test_and_set_bit_lock(bitnum, addr))) {
		preempt_enable();
		return 0;
	}
#endif
	__acquire(bitlock);
	return 1;
}

static inline void bit_spin_unlock(int bitnum, unsigned long *addr)
{
#ifdef CONFIG_DEBUG_SPINLOCK
	BUG_ON(!test_bit(bitnum, addr));
#endif
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
	clear_bit_unlock(bitnum, addr);
#endif
	preempt_enable();
	__release(bitlock);
}

static inline void __bit_spin_unlock(int bitnum, unsigned long *addr)
{
#ifdef CONFIG_DEBUG_SPINLOCK
	BUG_ON(!test_bit(bitnum, addr));
#endif
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
	__clear_bit_unlock(bitnum, addr);
#endif
	preempt_enable();
	__release(bitlock);
}

static inline int bit_spin_is_locked(int bitnum, unsigned long *addr)
{
#if defined(CONFIG_SMP) || defined(CONFIG_DEBUG_SPINLOCK)
	return test_bit(bitnum, addr);
#elif defined CONFIG_PREEMPT_COUNT
	return preempt_count();
#else
	return 1;
#endif
}

#endif