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
  77typedef int (*write_strategy_fn)(const char *buf, unsigned long long *val);
  78
  79int res_counter_memparse_write_strategy(const char *buf,
  80                                        unsigned long long *res);
  81
  82int res_counter_write(struct res_counter *counter, int member,
  83                      const char *buffer, write_strategy_fn write_strategy);
  84
  85/*
  86 * the field descriptors. one for each member of res_counter
  87 */
  88
  89enum {
  90        RES_USAGE,
  91        RES_MAX_USAGE,
  92        RES_LIMIT,
  93        RES_FAILCNT,
  94        RES_SOFT_LIMIT,
  95};
  96
  97/*
  98 * helpers for accounting
  99 */
 100
 101void res_counter_init(struct res_counter *counter, struct res_counter *parent);
 102
 103/*
 104 * charge - try to consume more resource.
 105 *
 106 * @counter: the counter
 107 * @val: the amount of the resource. each controller defines its own
 108 *       units, e.g. numbers, bytes, Kbytes, etc
 109 *
 110 * returns 0 on success and <0 if the counter->usage will exceed the
 111 * counter->limit _locked call expects the counter->lock to be taken
 112 *
 113 * charge_nofail works the same, except that it charges the resource
 114 * counter unconditionally, and returns < 0 if the after the current
 115 * charge we are over limit.
 116 */
 117
 118int __must_check res_counter_charge_locked(struct res_counter *counter,
 119                                           unsigned long val, bool force);
 120int __must_check res_counter_charge(struct res_counter *counter,
 121                unsigned long val, struct res_counter **limit_fail_at);
 122int res_counter_charge_nofail(struct res_counter *counter,
 123                unsigned long val, struct res_counter **limit_fail_at);
 124
 125/*
 126 * uncharge - tell that some portion of the resource is released
 127 *
 128 * @counter: the counter
 129 * @val: the amount of the resource
 130 *
 131 * these calls check for usage underflow and show a warning on the console
 132 * _locked call expects the counter->lock to be taken
 133 */
 134
 135void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
 136void res_counter_uncharge(struct res_counter *counter, unsigned long val);
 137
 138void res_counter_uncharge_until(struct res_counter *counter,
 139                                struct res_counter *top,
 140                                unsigned long val);
 141/**
 142 * res_counter_margin - calculate chargeable space of a counter
 143 * @cnt: the counter
 144 *
 145 * Returns the difference between the hard limit and the current usage
 146 * of resource counter @cnt.
 147 */
 148static inline unsigned long long res_counter_margin(struct res_counter *cnt)
 149{
 150        unsigned long long margin;
 151        unsigned long flags;
 152
 153        spin_lock_irqsave(&cnt->lock, flags);
 154        if (cnt->limit > cnt->usage)
 155                margin = cnt->limit - cnt->usage;
 156        else
 157                margin = 0;
 158        spin_unlock_irqrestore(&cnt->lock, flags);
 159        return margin;
 160}
 161
 162/**
 163 * Get the difference between the usage and the soft limit
 164 * @cnt: The counter
 165 *
 166 * Returns 0 if usage is less than or equal to soft limit
 167 * The difference between usage and soft limit, otherwise.
 168 */
 169static inline unsigned long long
 170res_counter_soft_limit_excess(struct res_counter *cnt)
 171{
 172        unsigned long long excess;
 173        unsigned long flags;
 174
 175        spin_lock_irqsave(&cnt->lock, flags);
 176        if (cnt->usage <= cnt->soft_limit)
 177                excess = 0;
 178        else
 179                excess = cnt->usage - cnt->soft_limit;
 180        spin_unlock_irqrestore(&cnt->lock, flags);
 181        return excess;
 182}
 183
 184static inline void res_counter_reset_max(struct res_counter *cnt)
 185{
 186        unsigned long flags;
 187
 188        spin_lock_irqsave(&cnt->lock, flags);
 189        cnt->max_usage = cnt->usage;
 190        spin_unlock_irqrestore(&cnt->lock, flags);
 191}
 192
 193static inline void res_counter_reset_failcnt(struct res_counter *cnt)
 194{
 195        unsigned long flags;
 196
 197        spin_lock_irqsave(&cnt->lock, flags);
 198        cnt->failcnt = 0;
 199        spin_unlock_irqrestore(&cnt->lock, flags);
 200}
 201
 202static inline int res_counter_set_limit(struct res_counter *cnt,
 203                unsigned long long limit)
 204{
 205        unsigned long flags;
 206        int ret = -EBUSY;
 207
 208        spin_lock_irqsave(&cnt->lock, flags);
 209        if (cnt->usage <= limit) {
 210                cnt->limit = limit;
 211                ret = 0;
 212        }
 213        spin_unlock_irqrestore(&cnt->lock, flags);
 214        return ret;
 215}
 216
 217static inline int
 218res_counter_set_soft_limit(struct res_counter *cnt,
 219                                unsigned long long soft_limit)
 220{
 221        unsigned long flags;
 222
 223        spin_lock_irqsave(&cnt->lock, flags);
 224        cnt->soft_limit = soft_limit;
 225        spin_unlock_irqrestore(&cnt->lock, flags);
 226        return 0;
 227}
 228
 229#endif
 230
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