linux/include/linux/res_counter.h
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   1#ifndef __RES_COUNTER_H__
   2#define __RES_COUNTER_H__
   3
   4/*
   5 * Resource Counters
   6 * Contain common data types and routines for resource accounting
   7 *
   8 * Copyright 2007 OpenVZ SWsoft Inc
   9 *
  10 * Author: Pavel Emelianov <xemul@openvz.org>
  11 *
  12 * See Documentation/cgroups/resource_counter.txt for more
  13 * info about what this counter is.
  14 */
  15
  16#include <linux/cgroup.h>
  17
  18/*
  19 * The core object. the cgroup that wishes to account for some
  20 * resource may include this counter into its structures and use
  21 * the helpers described beyond
  22 */
  23
  24struct res_counter {
  25        /*
  26         * the current resource consumption level
  27         */
  28        unsigned long long usage;
  29        /*
  30         * the maximal value of the usage from the counter creation
  31         */
  32        unsigned long long max_usage;
  33        /*
  34         * the limit that usage cannot exceed
  35         */
  36        unsigned long long limit;
  37        /*
  38         * the limit that usage can be exceed
  39         */
  40        unsigned long long soft_limit;
  41        /*
  42         * the number of unsuccessful attempts to consume the resource
  43         */
  44        unsigned long long failcnt;
  45        /*
  46         * the lock to protect all of the above.
  47         * the routines below consider this to be IRQ-safe
  48         */
  49        spinlock_t lock;
  50        /*
  51         * Parent counter, used for hierarchial resource accounting
  52         */
  53        struct res_counter *parent;
  54};
  55
  56#define RESOURCE_MAX (unsigned long long)LLONG_MAX
  57
  58/**
  59 * Helpers to interact with userspace
  60 * res_counter_read_u64() - returns the value of the specified member.
  61 * res_counter_read/_write - put/get the specified fields from the
  62 * res_counter struct to/from the user
  63 *
  64 * @counter:     the counter in question
  65 * @member:  the field to work with (see RES_xxx below)
  66 * @buf:     the buffer to opeate on,...
  67 * @nbytes:  its size...
  68 * @pos:     and the offset.
  69 */
  70
  71u64 res_counter_read_u64(struct res_counter *counter, int member);
  72
  73ssize_t res_counter_read(struct res_counter *counter, int member,
  74                const char __user *buf, size_t nbytes, loff_t *pos,
  75                int (*read_strategy)(unsigned long long val, char *s));
  76
  77int res_counter_memparse_write_strategy(const char *buf,
  78                                        unsigned long long *res);
  79
  80/*
  81 * the field descriptors. one for each member of res_counter
  82 */
  83
  84enum {
  85        RES_USAGE,
  86        RES_MAX_USAGE,
  87        RES_LIMIT,
  88        RES_FAILCNT,
  89        RES_SOFT_LIMIT,
  90};
  91
  92/*
  93 * helpers for accounting
  94 */
  95
  96void res_counter_init(struct res_counter *counter, struct res_counter *parent);
  97
  98/*
  99 * charge - try to consume more resource.
 100 *
 101 * @counter: the counter
 102 * @val: the amount of the resource. each controller defines its own
 103 *       units, e.g. numbers, bytes, Kbytes, etc
 104 *
 105 * returns 0 on success and <0 if the counter->usage will exceed the
 106 * counter->limit _locked call expects the counter->lock to be taken
 107 *
 108 * charge_nofail works the same, except that it charges the resource
 109 * counter unconditionally, and returns < 0 if the after the current
 110 * charge we are over limit.
 111 */
 112
 113int __must_check res_counter_charge_locked(struct res_counter *counter,
 114                                           unsigned long val, bool force);
 115int __must_check res_counter_charge(struct res_counter *counter,
 116                unsigned long val, struct res_counter **limit_fail_at);
 117int res_counter_charge_nofail(struct res_counter *counter,
 118                unsigned long val, struct res_counter **limit_fail_at);
 119
 120/*
 121 * uncharge - tell that some portion of the resource is released
 122 *
 123 * @counter: the counter
 124 * @val: the amount of the resource
 125 *
 126 * these calls check for usage underflow and show a warning on the console
 127 * _locked call expects the counter->lock to be taken
 128 *
 129 * returns the total charges still present in @counter.
 130 */
 131
 132u64 res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
 133u64 res_counter_uncharge(struct res_counter *counter, unsigned long val);
 134
 135u64 res_counter_uncharge_until(struct res_counter *counter,
 136                               struct res_counter *top,
 137                               unsigned long val);
 138/**
 139 * res_counter_margin - calculate chargeable space of a counter
 140 * @cnt: the counter
 141 *
 142 * Returns the difference between the hard limit and the current usage
 143 * of resource counter @cnt.
 144 */
 145static inline unsigned long long res_counter_margin(struct res_counter *cnt)
 146{
 147        unsigned long long margin;
 148        unsigned long flags;
 149
 150        spin_lock_irqsave(&cnt->lock, flags);
 151        if (cnt->limit > cnt->usage)
 152                margin = cnt->limit - cnt->usage;
 153        else
 154                margin = 0;
 155        spin_unlock_irqrestore(&cnt->lock, flags);
 156        return margin;
 157}
 158
 159/**
 160 * Get the difference between the usage and the soft limit
 161 * @cnt: The counter
 162 *
 163 * Returns 0 if usage is less than or equal to soft limit
 164 * The difference between usage and soft limit, otherwise.
 165 */
 166static inline unsigned long long
 167res_counter_soft_limit_excess(struct res_counter *cnt)
 168{
 169        unsigned long long excess;
 170        unsigned long flags;
 171
 172        spin_lock_irqsave(&cnt->lock, flags);
 173        if (cnt->usage <= cnt->soft_limit)
 174                excess = 0;
 175        else
 176                excess = cnt->usage - cnt->soft_limit;
 177        spin_unlock_irqrestore(&cnt->lock, flags);
 178        return excess;
 179}
 180
 181static inline void res_counter_reset_max(struct res_counter *cnt)
 182{
 183        unsigned long flags;
 184
 185        spin_lock_irqsave(&cnt->lock, flags);
 186        cnt->max_usage = cnt->usage;
 187        spin_unlock_irqrestore(&cnt->lock, flags);
 188}
 189
 190static inline void res_counter_reset_failcnt(struct res_counter *cnt)
 191{
 192        unsigned long flags;
 193
 194        spin_lock_irqsave(&cnt->lock, flags);
 195        cnt->failcnt = 0;
 196        spin_unlock_irqrestore(&cnt->lock, flags);
 197}
 198
 199static inline int res_counter_set_limit(struct res_counter *cnt,
 200                unsigned long long limit)
 201{
 202        unsigned long flags;
 203        int ret = -EBUSY;
 204
 205        spin_lock_irqsave(&cnt->lock, flags);
 206        if (cnt->usage <= limit) {
 207                cnt->limit = limit;
 208                ret = 0;
 209        }
 210        spin_unlock_irqrestore(&cnt->lock, flags);
 211        return ret;
 212}
 213
 214static inline int
 215res_counter_set_soft_limit(struct res_counter *cnt,
 216                                unsigned long long soft_limit)
 217{
 218        unsigned long flags;
 219
 220        spin_lock_irqsave(&cnt->lock, flags);
 221        cnt->soft_limit = soft_limit;
 222        spin_unlock_irqrestore(&cnt->lock, flags);
 223        return 0;
 224}
 225
 226#endif
 227
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