include/linux/res_counter.h

   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
  24 struct 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
  71 u64 res_counter_read_u64(struct res_counter *counter, int member);
  72
  73 ssize_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
  77 typedef int (*write_strategy_fn)(const char *buf, unsigned long long *val);
  78
  79 int res_counter_memparse_write_strategy(const char *buf,
  80                                         unsigned long long *res);
  81
  82 int 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
  89 enum {
  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
 101 void 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
 114 int __must_check res_counter_charge_locked(struct res_counter *counter,
 115                 unsigned long val);
 116 int __must_check res_counter_charge(struct res_counter *counter,
 117                 unsigned long val, struct res_counter **limit_fail_at);
 118
 119 /*
 120  * uncharge - tell that some portion of the resource is released
 121  *
 122  * @counter: the counter
 123  * @val: the amount of the resource
 124  *
 125  * these calls check for usage underflow and show a warning on the console
 126  * _locked call expects the counter->lock to be taken
 127  */
 128
 129 void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
 130 void res_counter_uncharge(struct res_counter *counter, unsigned long val);
 131
 132 /**
 133  * res_counter_margin - calculate chargeable space of a counter
 134  * @cnt: the counter
 135  *
 136  * Returns the difference between the hard limit and the current usage
 137  * of resource counter @cnt.
 138  */
 139 static inline unsigned long long res_counter_margin(struct res_counter *cnt)
 140 {
 141         unsigned long long margin;
 142         unsigned long flags;
 143
 144         spin_lock_irqsave(&cnt->lock, flags);
 145         margin = cnt->limit - cnt->usage;
 146         spin_unlock_irqrestore(&cnt->lock, flags);
 147         return margin;
 148 }
 149
 150 /**
 151  * Get the difference between the usage and the soft limit
 152  * @cnt: The counter
 153  *
 154  * Returns 0 if usage is less than or equal to soft limit
 155  * The difference between usage and soft limit, otherwise.
 156  */
 157 static inline unsigned long long
 158 res_counter_soft_limit_excess(struct res_counter *cnt)
 159 {
 160         unsigned long long excess;
 161         unsigned long flags;
 162
 163         spin_lock_irqsave(&cnt->lock, flags);
 164         if (cnt->usage <= cnt->soft_limit)
 165                 excess = 0;
 166         else
 167                 excess = cnt->usage - cnt->soft_limit;
 168         spin_unlock_irqrestore(&cnt->lock, flags);
 169         return excess;
 170 }
 171
 172 static inline void res_counter_reset_max(struct res_counter *cnt)
 173 {
 174         unsigned long flags;
 175
 176         spin_lock_irqsave(&cnt->lock, flags);
 177         cnt->max_usage = cnt->usage;
 178         spin_unlock_irqrestore(&cnt->lock, flags);
 179 }
 180
 181 static inline void res_counter_reset_failcnt(struct res_counter *cnt)
 182 {
 183         unsigned long flags;
 184
 185         spin_lock_irqsave(&cnt->lock, flags);
 186         cnt->failcnt = 0;
 187         spin_unlock_irqrestore(&cnt->lock, flags);
 188 }
 189
 190 static inline int res_counter_set_limit(struct res_counter *cnt,
 191                 unsigned long long limit)
 192 {
 193         unsigned long flags;
 194         int ret = -EBUSY;
 195
 196         spin_lock_irqsave(&cnt->lock, flags);
 197         if (cnt->usage <= limit) {
 198                 cnt->limit = limit;
 199                 ret = 0;
 200         }
 201         spin_unlock_irqrestore(&cnt->lock, flags);
 202         return ret;
 203 }
 204
 205 static inline int
 206 res_counter_set_soft_limit(struct res_counter *cnt,
 207                                 unsigned long long soft_limit)
 208 {
 209         unsigned long flags;
 210
 211         spin_lock_irqsave(&cnt->lock, flags);
 212         cnt->soft_limit = soft_limit;
 213         spin_unlock_irqrestore(&cnt->lock, flags);
 214         return 0;
 215 }
 216
 217 #endif