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 ssize_t res_counter_write(struct res_counter *counter, int member,
  67                 const char __user *buf, size_t nbytes, loff_t *pos,
  68                 int (*write_strategy)(char *buf, unsigned long long *val));
  69
  70 /*
  71  * the field descriptors. one for each member of res_counter
  72  */
  73
  74 enum {
  75         RES_USAGE,
  76         RES_MAX_USAGE,
  77         RES_LIMIT,
  78         RES_FAILCNT,
  79 };
  80
  81 /*
  82  * helpers for accounting
  83  */
  84
  85 void res_counter_init(struct res_counter *counter);
  86
  87 /*
  88  * charge - try to consume more resource.
  89  *
  90  * @counter: the counter
  91  * @val: the amount of the resource. each controller defines its own
  92  *       units, e.g. numbers, bytes, Kbytes, etc
  93  *
  94  * returns 0 on success and <0 if the counter->usage will exceed the
  95  * counter->limit _locked call expects the counter->lock to be taken
  96  */
  97
  98 int __must_check res_counter_charge_locked(struct res_counter *counter,
  99                 unsigned long val);
 100 int __must_check res_counter_charge(struct res_counter *counter,
 101                 unsigned long val);
 102
 103 /*
 104  * uncharge - tell that some portion of the resource is released
 105  *
 106  * @counter: the counter
 107  * @val: the amount of the resource
 108  *
 109  * these calls check for usage underflow and show a warning on the console
 110  * _locked call expects the counter->lock to be taken
 111  */
 112
 113 void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
 114 void res_counter_uncharge(struct res_counter *counter, unsigned long val);
 115
 116 static inline bool res_counter_limit_check_locked(struct res_counter *cnt)
 117 {
 118         if (cnt->usage < cnt->limit)
 119                 return true;
 120
 121         return false;
 122 }
 123
 124 /*
 125  * Helper function to detect if the cgroup is within it's limit or
 126  * not. It's currently called from cgroup_rss_prepare()
 127  */
 128 static inline bool res_counter_check_under_limit(struct res_counter *cnt)
 129 {
 130         bool ret;
 131         unsigned long flags;
 132
 133         spin_lock_irqsave(&cnt->lock, flags);
 134         ret = res_counter_limit_check_locked(cnt);
 135         spin_unlock_irqrestore(&cnt->lock, flags);
 136         return ret;
 137 }
 138
 139 static inline void res_counter_reset_max(struct res_counter *cnt)
 140 {
 141         unsigned long flags;
 142
 143         spin_lock_irqsave(&cnt->lock, flags);
 144         cnt->max_usage = cnt->usage;
 145         spin_unlock_irqrestore(&cnt->lock, flags);
 146 }
 147
 148 static inline void res_counter_reset_failcnt(struct res_counter *cnt)
 149 {
 150         unsigned long flags;
 151
 152         spin_lock_irqsave(&cnt->lock, flags);
 153         cnt->failcnt = 0;
 154         spin_unlock_irqrestore(&cnt->lock, flags);
 155 }
 156 #endif