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