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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>
*
* See Documentation/cgroups/resource_counter.txt for more
* info about what this counter is.
*/
#include <linux/spinlock.h>
#include <linux/errno.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 limit that usage can be exceed
*/
unsigned long long soft_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;
/*
* Parent counter, used for hierarchial resource accounting
*/
struct res_counter *parent;
};
#define RES_COUNTER_MAX ULLONG_MAX
/**
* 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));
int res_counter_memparse_write_strategy(const char *buf,
unsigned long long *res);
/*
* the field descriptors. one for each member of res_counter
*/
enum {
RES_USAGE,
RES_MAX_USAGE,
RES_LIMIT,
RES_FAILCNT,
RES_SOFT_LIMIT,
};
/*
* helpers for accounting
*/
void res_counter_init(struct res_counter *counter, struct res_counter *parent);
/*
* 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
*
* charge_nofail works the same, except that it charges the resource
* counter unconditionally, and returns < 0 if the after the current
* charge we are over limit.
*/
int __must_check res_counter_charge(struct res_counter *counter,
unsigned long val, struct res_counter **limit_fail_at);
int res_counter_charge_nofail(struct res_counter *counter,
unsigned long val, struct res_counter **limit_fail_at);
/*
* 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
*
* returns the total charges still present in @counter.
*/
u64 res_counter_uncharge(struct res_counter *counter, unsigned long val);
u64 res_counter_uncharge_until(struct res_counter *counter,
struct res_counter *top,
unsigned long val);
/**
* res_counter_margin - calculate chargeable space of a counter
* @cnt: the counter
*
* Returns the difference between the hard limit and the current usage
* of resource counter @cnt.
*/
static inline unsigned long long res_counter_margin(struct res_counter *cnt)
{
unsigned long long margin;
unsigned long flags;
spin_lock_irqsave(&cnt->lock, flags);
if (cnt->limit > cnt->usage)
margin = cnt->limit - cnt->usage;
else
margin = 0;
spin_unlock_irqrestore(&cnt->lock, flags);
return margin;
}
/**
* Get the difference between the usage and the soft limit
* @cnt: The counter
*
* Returns 0 if usage is less than or equal to soft limit
* The difference between usage and soft limit, otherwise.
*/
static inline unsigned long long
res_counter_soft_limit_excess(struct res_counter *cnt)
{
unsigned long long excess;
unsigned long flags;
spin_lock_irqsave(&cnt->lock, flags);
if (cnt->usage <= cnt->soft_limit)
excess = 0;
else
excess = cnt->usage - cnt->soft_limit;
spin_unlock_irqrestore(&cnt->lock, flags);
return excess;
}
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;
}
static inline int
res_counter_set_soft_limit(struct res_counter *cnt,
unsigned long long soft_limit)
{
unsigned long flags;
spin_lock_irqsave(&cnt->lock, flags);
cnt->soft_limit = soft_limit;
spin_unlock_irqrestore(&cnt->lock, flags);
return 0;
}
#endif
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