#ifndef __RES_COUNTER_H__

#define __RES_COUNTER_H__

/*

 * Resource Counters

 * Contain common data types and routines for resource accounting

 *

 * Copyright 2007 OpenVZ SWsoft Inc

 *

 * Author: Pavel Emelianov <xemul@openvz.org>

 *

 * info about what this counter is.

 */

#include <linux/cgroup.h>

/*

 * The core object. the cgroup that wishes to account for some

 * resource may include this counter into its structures and use

 * the helpers described beyond

 */

struct res_counter {

	/*

	 * the current resource consumption level

	 */

	unsigned long long usage;

	/*

	 * the maximal value of the usage from the counter creation

	 */

	unsigned long long max_usage;

	/*

	 * the limit that usage cannot exceed

	 */

	unsigned long long limit;

	/*

	 * the number of unsuccessful attempts to consume the resource

	 */

	unsigned long long failcnt;

	/*

	 * the lock to protect all of the above.

	 * the routines below consider this to be IRQ-safe

	 */

	spinlock_t lock;

};

/**

 * Helpers to interact with userspace

 * res_counter_read_u64() - returns the value of the specified member.

 * res_counter_read/_write - put/get the specified fields from the

 * res_counter struct to/from the user

 *

 * @counter:     the counter in question

 * @member:  the field to work with (see RES_xxx below)

 * @buf:     the buffer to opeate on,...

 * @nbytes:  its size...

 * @pos:     and the offset.

 */

u64 res_counter_read_u64(struct res_counter *counter, int member);

ssize_t res_counter_read(struct res_counter *counter, int member,

		const char __user *buf, size_t nbytes, loff_t *pos,

		int (*read_strategy)(unsigned long long val, char *s));

typedef int (*write_strategy_fn)(const char *buf, unsigned long long *val);

int res_counter_memparse_write_strategy(const char *buf,

					unsigned long long *res);

int res_counter_write(struct res_counter *counter, int member,

		      const char *buffer, write_strategy_fn write_strategy);

/*

 * the field descriptors. one for each member of res_counter

 */

enum {

	RES_USAGE,

	RES_MAX_USAGE,

	RES_LIMIT,

	RES_FAILCNT,

};

/*

 * helpers for accounting

 */

/*

 * charge - try to consume more resource.

 *

 * @counter: the counter

 * @val: the amount of the resource. each controller defines its own

 *       units, e.g. numbers, bytes, Kbytes, etc

 *

 * returns 0 on success and <0 if the counter->usage will exceed the

 * counter->limit _locked call expects the counter->lock to be taken

 */

int __must_check res_counter_charge_locked(struct res_counter *counter,

		unsigned long val);

int __must_check res_counter_charge(struct res_counter *counter,

/*

 * uncharge - tell that some portion of the resource is released

 *

 * @counter: the counter

 * @val: the amount of the resource

 *

 * these calls check for usage underflow and show a warning on the console

 * _locked call expects the counter->lock to be taken

 */

void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);

void res_counter_uncharge(struct res_counter *counter, unsigned long val);

static inline bool res_counter_limit_check_locked(struct res_counter *cnt)

{

	if (cnt->usage < cnt->limit)

		return true;

	return false;

}

/*

 * Helper function to detect if the cgroup is within it's limit or

 * not. It's currently called from cgroup_rss_prepare()

 */

static inline bool res_counter_check_under_limit(struct res_counter *cnt)

{

	bool ret;

	unsigned long flags;

	spin_lock_irqsave(&cnt->lock, flags);

	ret = res_counter_limit_check_locked(cnt);

	spin_unlock_irqrestore(&cnt->lock, flags);

	return ret;

}

static inline void res_counter_reset_max(struct res_counter *cnt)

{

	unsigned long flags;

	spin_lock_irqsave(&cnt->lock, flags);

	cnt->max_usage = cnt->usage;

	spin_unlock_irqrestore(&cnt->lock, flags);

}

static inline void res_counter_reset_failcnt(struct res_counter *cnt)

{

	unsigned long flags;

	spin_lock_irqsave(&cnt->lock, flags);

	cnt->failcnt = 0;

	spin_unlock_irqrestore(&cnt->lock, flags);

}

static inline int res_counter_set_limit(struct res_counter *cnt,

		unsigned long long limit)

{

	unsigned long flags;

	int ret = -EBUSY;

	spin_lock_irqsave(&cnt->lock, flags);

	if (cnt->usage <= limit) {

		cnt->limit = limit;

		ret = 0;

	}

	spin_unlock_irqrestore(&cnt->lock, flags);

	return ret;

}

#endif