kernel/res_counter.c

   1 /*
   2  * resource cgroups
   3  *
   4  * Copyright 2007 OpenVZ SWsoft Inc
   5  *
   6  * Author: Pavel Emelianov <xemul@openvz.org>
   7  *
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/parser.h>
  12 #include <linux/fs.h>
  13 #include <linux/slab.h>
  14 #include <linux/res_counter.h>
  15 #include <linux/uaccess.h>
  16 #include <linux/mm.h>
  17
  18 void res_counter_init(struct res_counter *counter)
  19 {
  20         spin_lock_init(&counter->lock);
  21         counter->limit = (unsigned long long)LLONG_MAX;
  22 }
  23
  24 int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
  25 {
  26         if (counter->usage + val > counter->limit) {
  27                 counter->failcnt++;
  28                 return -ENOMEM;
  29         }
  30
  31         counter->usage += val;
  32         if (counter->usage > counter->max_usage)
  33                 counter->max_usage = counter->usage;
  34         return 0;
  35 }
  36
  37 int res_counter_charge(struct res_counter *counter, unsigned long val)
  38 {
  39         int ret;
  40         unsigned long flags;
  41
  42         spin_lock_irqsave(&counter->lock, flags);
  43         ret = res_counter_charge_locked(counter, val);
  44         spin_unlock_irqrestore(&counter->lock, flags);
  45         return ret;
  46 }
  47
  48 void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val)
  49 {
  50         if (WARN_ON(counter->usage < val))
  51                 val = counter->usage;
  52
  53         counter->usage -= val;
  54 }
  55
  56 void res_counter_uncharge(struct res_counter *counter, unsigned long val)
  57 {
  58         unsigned long flags;
  59
  60         spin_lock_irqsave(&counter->lock, flags);
  61         res_counter_uncharge_locked(counter, val);
  62         spin_unlock_irqrestore(&counter->lock, flags);
  63 }
  64
  65
  66 static inline unsigned long long *
  67 res_counter_member(struct res_counter *counter, int member)
  68 {
  69         switch (member) {
  70         case RES_USAGE:
  71                 return &counter->usage;
  72         case RES_MAX_USAGE:
  73                 return &counter->max_usage;
  74         case RES_LIMIT:
  75                 return &counter->limit;
  76         case RES_FAILCNT:
  77                 return &counter->failcnt;
  78         };
  79
  80         BUG();
  81         return NULL;
  82 }
  83
  84 ssize_t res_counter_read(struct res_counter *counter, int member,
  85                 const char __user *userbuf, size_t nbytes, loff_t *pos,
  86                 int (*read_strategy)(unsigned long long val, char *st_buf))
  87 {
  88         unsigned long long *val;
  89         char buf[64], *s;
  90
  91         s = buf;
  92         val = res_counter_member(counter, member);
  93         if (read_strategy)
  94                 s += read_strategy(*val, s);
  95         else
  96                 s += sprintf(s, "%llu\n", *val);
  97         return simple_read_from_buffer((void __user *)userbuf, nbytes,
  98                         pos, buf, s - buf);
  99 }
 100
 101 u64 res_counter_read_u64(struct res_counter *counter, int member)
 102 {
 103         return *res_counter_member(counter, member);
 104 }
 105
 106 int res_counter_memparse_write_strategy(const char *buf,
 107                                         unsigned long long *res)
 108 {
 109         char *end;
 110         /* FIXME - make memparse() take const char* args */
 111         *res = memparse((char *)buf, &end);
 112         if (*end != '\0')
 113                 return -EINVAL;
 114
 115         *res = PAGE_ALIGN(*res);
 116         return 0;
 117 }
 118
 119 int res_counter_write(struct res_counter *counter, int member,
 120                       const char *buf, write_strategy_fn write_strategy)
 121 {
 122         char *end;
 123         unsigned long flags;
 124         unsigned long long tmp, *val;
 125
 126         if (write_strategy) {
 127                 if (write_strategy(buf, &tmp))
 128                         return -EINVAL;
 129         } else {
 130                 tmp = simple_strtoull(buf, &end, 10);
 131                 if (*end != '\0')
 132                         return -EINVAL;
 133         }
 134         spin_lock_irqsave(&counter->lock, flags);
 135         val = res_counter_member(counter, member);
 136         *val = tmp;
 137         spin_unlock_irqrestore(&counter->lock, flags);
 138         return 0;
 139 }