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 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 #define RESOURCE_MAX (unsigned long long)LLONG_MAX
  53
  54 /**
  55  * Helpers to interact with userspace
  56  * res_counter_read_u64() - returns the value of the specified member.
  57  * res_counter_read/_write - put/get the specified fields from the
  58  * res_counter struct to/from the user
  59  *
  60  * @counter:     the counter in question
  61  * @member:  the field to work with (see RES_xxx below)
  62  * @buf:     the buffer to opeate on,...
  63  * @nbytes:  its size...
  64  * @pos:     and the offset.
  65  */
  66
  67 u64 res_counter_read_u64(struct res_counter *counter, int member);
  68
  69 ssize_t res_counter_read(struct res_counter *counter, int member,
  70                 const char __user *buf, size_t nbytes, loff_t *pos,
  71                 int (*read_strategy)(unsigned long long val, char *s));
  72
  73 typedef int (*write_strategy_fn)(const char *buf, unsigned long long *val);
  74
  75 int res_counter_memparse_write_strategy(const char *buf,
  76                                         unsigned long long *res);
  77
  78 int res_counter_write(struct res_counter *counter, int member,
  79                       const char *buffer, write_strategy_fn write_strategy);
  80
  81 /*
  82  * the field descriptors. one for each member of res_counter
  83  */
  84
  85 enum {
  86         RES_USAGE,
  87         RES_MAX_USAGE,
  88         RES_LIMIT,
  89         RES_FAILCNT,
  90 };
  91
  92 /*
  93  * helpers for accounting
  94  */
  95
  96 void res_counter_init(struct res_counter *counter, struct res_counter *parent);
  97
  98 /*
  99  * charge - try to consume more resource.
 100  *
 101  * @counter: the counter
 102  * @val: the amount of the resource. each controller defines its own
 103  *       units, e.g. numbers, bytes, Kbytes, etc
 104  *
 105  * returns 0 on success and <0 if the counter->usage will exceed the
 106  * counter->limit _locked call expects the counter->lock to be taken
 107  */
 108
 109 int __must_check res_counter_charge_locked(struct res_counter *counter,
 110                 unsigned long val);
 111 int __must_check res_counter_charge(struct res_counter *counter,
 112                 unsigned long val, struct res_counter **limit_fail_at);
 113
 114 /*
 115  * uncharge - tell that some portion of the resource is released
 116  *
 117  * @counter: the counter
 118  * @val: the amount of the resource
 119  *
 120  * these calls check for usage underflow and show a warning on the console
 121  * _locked call expects the counter->lock to be taken
 122  */
 123
 124 void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
 125 void res_counter_uncharge(struct res_counter *counter, unsigned long val);
 126
 127 static inline bool res_counter_limit_check_locked(struct res_counter *cnt)
 128 {
 129         if (cnt->usage < cnt->limit)
 130                 return true;
 131
 132         return false;
 133 }
 134
 135 /*
 136  * Helper function to detect if the cgroup is within it's limit or
 137  * not. It's currently called from cgroup_rss_prepare()
 138  */
 139 static inline bool res_counter_check_under_limit(struct res_counter *cnt)
 140 {
 141         bool ret;
 142         unsigned long flags;
 143
 144         spin_lock_irqsave(&cnt->lock, flags);
 145         ret = res_counter_limit_check_locked(cnt);
 146         spin_unlock_irqrestore(&cnt->lock, flags);
 147         return ret;
 148 }
 149
 150 static inline void res_counter_reset_max(struct res_counter *cnt)
 151 {
 152         unsigned long flags;
 153
 154         spin_lock_irqsave(&cnt->lock, flags);
 155         cnt->max_usage = cnt->usage;
 156         spin_unlock_irqrestore(&cnt->lock, flags);
 157 }
 158
 159 static inline void res_counter_reset_failcnt(struct res_counter *cnt)
 160 {
 161         unsigned long flags;
 162
 163         spin_lock_irqsave(&cnt->lock, flags);
 164         cnt->failcnt = 0;
 165         spin_unlock_irqrestore(&cnt->lock, flags);
 166 }
 167
 168 static inline int res_counter_set_limit(struct res_counter *cnt,
 169                 unsigned long long limit)
 170 {
 171         unsigned long flags;
 172         int ret = -EBUSY;
 173
 174         spin_lock_irqsave(&cnt->lock, flags);
 175         if (cnt->usage <= limit) {
 176                 cnt->limit = limit;
 177                 ret = 0;
 178         }
 179         spin_unlock_irqrestore(&cnt->lock, flags);
 180         return ret;
 181 }
 182
 183 #endif