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/controllers/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 number of unsuccessful attempts to consume the resource
  39          */
  40         unsigned long long failcnt;
  41         /*
  42          * the lock to protect all of the above.
  43          * the routines below consider this to be IRQ-safe
  44          */
  45         spinlock_t lock;
  46         /*
  47          * Parent counter, used for hierarchial resource accounting
  48          */
  49         struct res_counter *parent;
  50 };
  51
  52 /**
  53  * Helpers to interact with userspace
  54  * res_counter_read_u64() - returns the value of the specified member.
  55  * res_counter_read/_write - put/get the specified fields from the
  56  * res_counter struct to/from the user
  57  *
  58  * @counter:     the counter in question
  59  * @member:  the field to work with (see RES_xxx below)
  60  * @buf:     the buffer to opeate on,...
  61  * @nbytes:  its size...
  62  * @pos:     and the offset.
  63  */
  64
  65 u64 res_counter_read_u64(struct res_counter *counter, int member);
  66
  67 ssize_t res_counter_read(struct res_counter *counter, int member,
  68                 const char __user *buf, size_t nbytes, loff_t *pos,
  69                 int (*read_strategy)(unsigned long long val, char *s));
  70
  71 typedef int (*write_strategy_fn)(const char *buf, unsigned long long *val);
  72
  73 int res_counter_memparse_write_strategy(const char *buf,
  74                                         unsigned long long *res);
  75
  76 int res_counter_write(struct res_counter *counter, int member,
  77                       const char *buffer, write_strategy_fn write_strategy);
  78
  79 /*
  80  * the field descriptors. one for each member of res_counter
  81  */
  82
  83 enum {
  84         RES_USAGE,
  85         RES_MAX_USAGE,
  86         RES_LIMIT,
  87         RES_FAILCNT,
  88 };
  89
  90 /*
  91  * helpers for accounting
  92  */
  93
  94 void res_counter_init(struct res_counter *counter, struct res_counter *parent);
  95
  96 /*
  97  * charge - try to consume more resource.
  98  *
  99  * @counter: the counter
 100  * @val: the amount of the resource. each controller defines its own
 101  *       units, e.g. numbers, bytes, Kbytes, etc
 102  *
 103  * returns 0 on success and <0 if the counter->usage will exceed the
 104  * counter->limit _locked call expects the counter->lock to be taken
 105  */
 106
 107 int __must_check res_counter_charge_locked(struct res_counter *counter,
 108                 unsigned long val);
 109 int __must_check res_counter_charge(struct res_counter *counter,
 110                 unsigned long val, struct res_counter **limit_fail_at);
 111
 112 /*
 113  * uncharge - tell that some portion of the resource is released
 114  *
 115  * @counter: the counter
 116  * @val: the amount of the resource
 117  *
 118  * these calls check for usage underflow and show a warning on the console
 119  * _locked call expects the counter->lock to be taken
 120  */
 121
 122 void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
 123 void res_counter_uncharge(struct res_counter *counter, unsigned long val);
 124
 125 static inline bool res_counter_limit_check_locked(struct res_counter *cnt)
 126 {
 127         if (cnt->usage < cnt->limit)
 128                 return true;
 129
 130         return false;
 131 }
 132
 133 /*
 134  * Helper function to detect if the cgroup is within it's limit or
 135  * not. It's currently called from cgroup_rss_prepare()
 136  */
 137 static inline bool res_counter_check_under_limit(struct res_counter *cnt)
 138 {
 139         bool ret;
 140         unsigned long flags;
 141
 142         spin_lock_irqsave(&cnt->lock, flags);
 143         ret = res_counter_limit_check_locked(cnt);
 144         spin_unlock_irqrestore(&cnt->lock, flags);
 145         return ret;
 146 }
 147
 148 static inline void res_counter_reset_max(struct res_counter *cnt)
 149 {
 150         unsigned long flags;
 151
 152         spin_lock_irqsave(&cnt->lock, flags);
 153         cnt->max_usage = cnt->usage;
 154         spin_unlock_irqrestore(&cnt->lock, flags);
 155 }
 156
 157 static inline void res_counter_reset_failcnt(struct res_counter *cnt)
 158 {
 159         unsigned long flags;
 160
 161         spin_lock_irqsave(&cnt->lock, flags);
 162         cnt->failcnt = 0;
 163         spin_unlock_irqrestore(&cnt->lock, flags);
 164 }
 165
 166 static inline int res_counter_set_limit(struct res_counter *cnt,
 167                 unsigned long long limit)
 168 {
 169         unsigned long flags;
 170         int ret = -EBUSY;
 171
 172         spin_lock_irqsave(&cnt->lock, flags);
 173         if (cnt->usage <= limit) {
 174                 cnt->limit = limit;
 175                 ret = 0;
 176         }
 177         spin_unlock_irqrestore(&cnt->lock, flags);
 178         return ret;
 179 }
 180
 181 #endif