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#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>
*
*/
#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 usage;
/*
* the limit that usage cannot exceed
*/
unsigned long limit;
/*
* the number of unsuccessful attempts to consume the resource
*/
unsigned 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/_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.
*/
ssize_t res_counter_read(struct res_counter *counter, int member,
const char __user *buf, size_t nbytes, loff_t *pos);
ssize_t res_counter_write(struct res_counter *counter, int member,
const char __user *buf, size_t nbytes, loff_t *pos);
/*
* the field descriptors. one for each member of res_counter
*/
enum {
RES_USAGE,
RES_LIMIT,
RES_FAILCNT,
};
/*
* helpers for accounting
*/
void res_counter_init(struct res_counter *counter);
/*
* 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 res_counter_charge_locked(struct res_counter *counter, unsigned long val);
int res_counter_charge(struct res_counter *counter, unsigned long val);
/*
* 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);
#endif
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