/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _LINUX_PERCPU_COUNTER_H
#define _LINUX_PERCPU_COUNTER_H


#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/list.h>
#include <linux/threads.h>
#include <linux/percpu.h>
#include <linux/types.h>
#include <linux/gfp.h>


#define PERCPU_COUNTER_LOCAL_BATCH	INT_MAX

#ifdef CONFIG_SMP

struct percpu_counter {
	raw_spinlock_t lock;
	s64 count;
#ifdef CONFIG_HOTPLUG_CPU
	struct list_head list;	
#endif
	s32 __percpu *counters;
};

extern int percpu_counter_batch;

int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp,
			  struct lock_class_key *key);

#define percpu_counter_init(fbc, value, gfp)				\
	({								\
		static struct lock_class_key __key;			\
									\
		__percpu_counter_init(fbc, value, gfp, &__key);		\
	})

void percpu_counter_destroy(struct percpu_counter *fbc);
void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount,
			      s32 batch);
s64 __percpu_counter_sum(struct percpu_counter *fbc);
int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch);
void percpu_counter_sync(struct percpu_counter *fbc);

static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
{
	return __percpu_counter_compare(fbc, rhs, percpu_counter_batch);
}

static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
{
	percpu_counter_add_batch(fbc, amount, percpu_counter_batch);
}


static inline void
percpu_counter_add_local(struct percpu_counter *fbc, s64 amount)
{
	percpu_counter_add_batch(fbc, amount, PERCPU_COUNTER_LOCAL_BATCH);
}

static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
{
	s64 ret = __percpu_counter_sum(fbc);
	return ret < 0 ? 0 : ret;
}

static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
{
	return __percpu_counter_sum(fbc);
}

static inline s64 percpu_counter_read(struct percpu_counter *fbc)
{
	return fbc->count;
}


static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
{
	
	s64 ret = READ_ONCE(fbc->count);

	if (ret >= 0)
		return ret;
	return 0;
}

static inline bool percpu_counter_initialized(struct percpu_counter *fbc)
{
	return (fbc->counters != NULL);
}

#else 

struct percpu_counter {
	s64 count;
};

static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount,
				      gfp_t gfp)
{
	fbc->count = amount;
	return 0;
}

static inline void percpu_counter_destroy(struct percpu_counter *fbc)
{
}

static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
{
	fbc->count = amount;
}

static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
{
	if (fbc->count > rhs)
		return 1;
	else if (fbc->count < rhs)
		return -1;
	else
		return 0;
}

static inline int
__percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch)
{
	return percpu_counter_compare(fbc, rhs);
}

static inline void
percpu_counter_add(struct percpu_counter *fbc, s64 amount)
{
	preempt_disable();
	fbc->count += amount;
	preempt_enable();
}


static inline void
percpu_counter_add_local(struct percpu_counter *fbc, s64 amount)
{
	percpu_counter_add(fbc, amount);
}

static inline void
percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch)
{
	percpu_counter_add(fbc, amount);
}

static inline s64 percpu_counter_read(struct percpu_counter *fbc)
{
	return fbc->count;
}


static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
{
	return fbc->count;
}

static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
{
	return percpu_counter_read_positive(fbc);
}

static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
{
	return percpu_counter_read(fbc);
}

static inline bool percpu_counter_initialized(struct percpu_counter *fbc)
{
	return true;
}

static inline void percpu_counter_sync(struct percpu_counter *fbc)
{
}
#endif	

static inline void percpu_counter_inc(struct percpu_counter *fbc)
{
	percpu_counter_add(fbc, 1);
}

static inline void percpu_counter_dec(struct percpu_counter *fbc)
{
	percpu_counter_add(fbc, -1);
}

static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
{
	percpu_counter_add(fbc, -amount);
}

static inline void
percpu_counter_sub_local(struct percpu_counter *fbc, s64 amount)
{
	percpu_counter_add_local(fbc, -amount);
}

#endif 
