Edit File: res_counter.h
#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 RESOURCE_MAX (unsigned long long)LLONG_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 _locked call expects the counter->lock to be taken * * 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_locked(struct res_counter *counter, unsigned long val, bool force); 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 * _locked call expects the counter->lock to be taken * * returns the total charges still present in @counter. */ u64 res_counter_uncharge_locked(struct res_counter *counter, unsigned long val); 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