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/spinlock.h>
  17 #include <linux/errno.h>
  18
  19 /*
  20  * The core object. the cgroup that wishes to account for some
  21  * resource may include this counter into its structures and use
  22  * the helpers described beyond
  23  */
  24
  25 struct res_counter {
  26         /*
  27          * the current resource consumption level
  28          */
  29         unsigned long long usage;
  30         /*
  31          * the maximal value of the usage from the counter creation
  32          */
  33         unsigned long long max_usage;
  34         /*
  35          * the limit that usage cannot exceed
  36          */
  37         unsigned long long limit;
  38         /*
  39          * the limit that usage can be exceed
  40          */
  41         unsigned long long soft_limit;
  42         /*
  43          * the number of unsuccessful attempts to consume the resource
  44          */
  45         unsigned long long failcnt;
  46         /*
  47          * the lock to protect all of the above.
  48          * the routines below consider this to be IRQ-safe
  49          */
  50         spinlock_t lock;
  51         /*
  52          * Parent counter, used for hierarchial resource accounting
  53          */
  54         struct res_counter *parent;
  55 };
  56
  57 #define RES_COUNTER_MAX ULLONG_MAX
  58
  59 /**
  60  * Helpers to interact with userspace
  61  * res_counter_read_u64() - returns the value of the specified member.
  62  * res_counter_read/_write - put/get the specified fields from the
  63  * res_counter struct to/from the user
  64  *
  65  * @counter:     the counter in question
  66  * @member:  the field to work with (see RES_xxx below)
  67  * @buf:     the buffer to opeate on,...
  68  * @nbytes:  its size...
  69  * @pos:     and the offset.
  70  */
  71
  72 u64 res_counter_read_u64(struct res_counter *counter, int member);
  73
  74 ssize_t res_counter_read(struct res_counter *counter, int member,
  75                 const char __user *buf, size_t nbytes, loff_t *pos,
  76                 int (*read_strategy)(unsigned long long val, char *s));
  77
  78 int res_counter_memparse_write_strategy(const char *buf,
  79                                         unsigned long long *res);
  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         RES_SOFT_LIMIT,
  91 };
  92
  93 /*
  94  * helpers for accounting
  95  */
  96
  97 void res_counter_init(struct res_counter *counter, struct res_counter *parent);
  98
  99 /*
 100  * charge - try to consume more resource.
 101  *
 102  * @counter: the counter
 103  * @val: the amount of the resource. each controller defines its own
 104  *       units, e.g. numbers, bytes, Kbytes, etc
 105  *
 106  * returns 0 on success and <0 if the counter->usage will exceed the
 107  * counter->limit
 108  *
 109  * charge_nofail works the same, except that it charges the resource
 110  * counter unconditionally, and returns < 0 if the after the current
 111  * charge we are over limit.
 112  */
 113
 114 int __must_check res_counter_charge(struct res_counter *counter,
 115                 unsigned long val, struct res_counter **limit_fail_at);
 116 int res_counter_charge_nofail(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  *
 127  * returns the total charges still present in @counter.
 128  */
 129
 130 u64 res_counter_uncharge(struct res_counter *counter, unsigned long val);
 131
 132 u64 res_counter_uncharge_until(struct res_counter *counter,
 133                                struct res_counter *top,
 134                                unsigned long val);
 135 /**
 136  * res_counter_margin - calculate chargeable space of a counter
 137  * @cnt: the counter
 138  *
 139  * Returns the difference between the hard limit and the current usage
 140  * of resource counter @cnt.
 141  */
 142 static inline unsigned long long res_counter_margin(struct res_counter *cnt)
 143 {
 144         unsigned long long margin;
 145         unsigned long flags;
 146
 147         spin_lock_irqsave(&cnt->lock, flags);
 148         if (cnt->limit > cnt->usage)
 149                 margin = cnt->limit - cnt->usage;
 150         else
 151                 margin = 0;
 152         spin_unlock_irqrestore(&cnt->lock, flags);
 153         return margin;
 154 }
 155
 156 /**
 157  * Get the difference between the usage and the soft limit
 158  * @cnt: The counter
 159  *
 160  * Returns 0 if usage is less than or equal to soft limit
 161  * The difference between usage and soft limit, otherwise.
 162  */
 163 static inline unsigned long long
 164 res_counter_soft_limit_excess(struct res_counter *cnt)
 165 {
 166         unsigned long long excess;
 167         unsigned long flags;
 168
 169         spin_lock_irqsave(&cnt->lock, flags);
 170         if (cnt->usage <= cnt->soft_limit)
 171                 excess = 0;
 172         else
 173                 excess = cnt->usage - cnt->soft_limit;
 174         spin_unlock_irqrestore(&cnt->lock, flags);
 175         return excess;
 176 }
 177
 178 static inline void res_counter_reset_max(struct res_counter *cnt)
 179 {
 180         unsigned long flags;
 181
 182         spin_lock_irqsave(&cnt->lock, flags);
 183         cnt->max_usage = cnt->usage;
 184         spin_unlock_irqrestore(&cnt->lock, flags);
 185 }
 186
 187 static inline void res_counter_reset_failcnt(struct res_counter *cnt)
 188 {
 189         unsigned long flags;
 190
 191         spin_lock_irqsave(&cnt->lock, flags);
 192         cnt->failcnt = 0;
 193         spin_unlock_irqrestore(&cnt->lock, flags);
 194 }
 195
 196 static inline int res_counter_set_limit(struct res_counter *cnt,
 197                 unsigned long long limit)
 198 {
 199         unsigned long flags;
 200         int ret = -EBUSY;
 201
 202         spin_lock_irqsave(&cnt->lock, flags);
 203         if (cnt->usage <= limit) {
 204                 cnt->limit = limit;
 205                 ret = 0;
 206         }
 207         spin_unlock_irqrestore(&cnt->lock, flags);
 208         return ret;
 209 }
 210
 211 static inline int
 212 res_counter_set_soft_limit(struct res_counter *cnt,
 213                                 unsigned long long soft_limit)
 214 {
 215         unsigned long flags;
 216
 217         spin_lock_irqsave(&cnt->lock, flags);
 218         cnt->soft_limit = soft_limit;
 219         spin_unlock_irqrestore(&cnt->lock, flags);
 220         return 0;
 221 }
 222
 223 #endif