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/* Copyright (C) 1991-2017, the Linux Kernel authors */
#ifndef _LINUX_PERCPU_COUNTER_H
#define _LINUX_PERCPU_COUNTER_H
/*
* A simple "approximate counter".
*/
#include <atomic.h>
#include <list.h>
struct percpu_counter {
spinlock_t lock;
int64_t count;
#ifdef CONFIG_HOTPLUG_CPU
struct list_head list; /* All percpu_counters are on a list */
#endif
int32_t *counters;
};
extern int percpu_counter_batch;
int percpu_counter_init(struct percpu_counter *fbc, int64_t amount, int gfp);
void percpu_counter_destroy(struct percpu_counter *fbc);
void percpu_counter_set(struct percpu_counter *fbc, int64_t amount);
void percpu_counter_add_batch(struct percpu_counter *fbc, int64_t amount,
int32_t batch);
int64_t __percpu_counter_sum(struct percpu_counter *fbc);
int __percpu_counter_compare(struct percpu_counter *fbc, int64_t rhs,
int32_t batch);
static inline int percpu_counter_compare(struct percpu_counter *fbc,
int64_t rhs)
{
return __percpu_counter_compare(fbc, rhs, percpu_counter_batch);
}
static inline void percpu_counter_add(struct percpu_counter *fbc,
int64_t amount)
{
percpu_counter_add_batch(fbc, amount, percpu_counter_batch);
}
static inline int64_t percpu_counter_sum_positive(struct percpu_counter *fbc)
{
int64_t ret = __percpu_counter_sum(fbc);
return ret < 0 ? 0 : ret;
}
static inline int64_t percpu_counter_sum(struct percpu_counter *fbc)
{
return __percpu_counter_sum(fbc);
}
static inline int64_t percpu_counter_read(struct percpu_counter *fbc)
{
return fbc->count;
}
/*
* It is possible for the percpu_counter_read() to return a small negative
* number for some counter which should never be negative.
*
*/
static inline int64_t percpu_counter_read_positive(struct percpu_counter *fbc)
{
int64_t ret = fbc->count;
cmb(); /* Prevent reloads of fbc->count */
if (ret >= 0)
return ret;
return 0;
}
static inline int percpu_counter_initialized(struct percpu_counter *fbc)
{
return (fbc->counters != NULL);
}
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,
int64_t amount)
{
percpu_counter_add(fbc, -amount);
}
#endif /* _LINUX_PERCPU_COUNTER_H */