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
  17 void res_counter_init(struct res_counter *counter)
  18 {
  19         spin_lock_init(&counter->lock);
  20         counter->limit = (unsigned long long)LLONG_MAX;
  21 }
  22
  23 int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
  24 {
  25         if (counter->usage + val > counter->limit) {
  26                 counter->failcnt++;
  27                 return -ENOMEM;
  28         }
  29
  30         counter->usage += val;
  31         if (counter->usage > counter->max_usage)
  32                 counter->max_usage = counter->usage;
  33         return 0;
  34 }
  35
  36 int res_counter_charge(struct res_counter *counter, unsigned long val)
  37 {
  38         int ret;
  39         unsigned long flags;
  40
  41         spin_lock_irqsave(&counter->lock, flags);
  42         ret = res_counter_charge_locked(counter, val);
  43         spin_unlock_irqrestore(&counter->lock, flags);
  44         return ret;
  45 }
  46
  47 void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val)
  48 {
  49         if (WARN_ON(counter->usage < val))
  50                 val = counter->usage;
  51
  52         counter->usage -= val;
  53 }
  54
  55 void res_counter_uncharge(struct res_counter *counter, unsigned long val)
  56 {
  57         unsigned long flags;
  58
  59         spin_lock_irqsave(&counter->lock, flags);
  60         res_counter_uncharge_locked(counter, val);
  61         spin_unlock_irqrestore(&counter->lock, flags);
  62 }
  63
  64
  65 static inline unsigned long long *
  66 res_counter_member(struct res_counter *counter, int member)
  67 {
  68         switch (member) {
  69         case RES_USAGE:
  70                 return &counter->usage;
  71         case RES_MAX_USAGE:
  72                 return &counter->max_usage;
  73         case RES_LIMIT:
  74                 return &counter->limit;
  75         case RES_FAILCNT:
  76                 return &counter->failcnt;
  77         };
  78
  79         BUG();
  80         return NULL;
  81 }
  82
  83 ssize_t res_counter_read(struct res_counter *counter, int member,
  84                 const char __user *userbuf, size_t nbytes, loff_t *pos,
  85                 int (*read_strategy)(unsigned long long val, char *st_buf))
  86 {
  87         unsigned long long *val;
  88         char buf[64], *s;
  89
  90         s = buf;
  91         val = res_counter_member(counter, member);
  92         if (read_strategy)
  93                 s += read_strategy(*val, s);
  94         else
  95                 s += sprintf(s, "%llu\n", *val);
  96         return simple_read_from_buffer((void __user *)userbuf, nbytes,
  97                         pos, buf, s - buf);
  98 }
  99
 100 u64 res_counter_read_u64(struct res_counter *counter, int member)
 101 {
 102         return *res_counter_member(counter, member);
 103 }
 104
 105 ssize_t res_counter_write(struct res_counter *counter, int member,
 106                 const char __user *userbuf, size_t nbytes, loff_t *pos,
 107                 int (*write_strategy)(char *st_buf, unsigned long long *val))
 108 {
 109         int ret;
 110         char *buf, *end;
 111         unsigned long flags;
 112         unsigned long long tmp, *val;
 113
 114         buf = kmalloc(nbytes + 1, GFP_KERNEL);
 115         ret = -ENOMEM;
 116         if (buf == NULL)
 117                 goto out;
 118
 119         buf[nbytes] = '\0';
 120         ret = -EFAULT;
 121         if (copy_from_user(buf, userbuf, nbytes))
 122                 goto out_free;
 123
 124         ret = -EINVAL;
 125
 126         strstrip(buf);
 127         if (write_strategy) {
 128                 if (write_strategy(buf, &tmp)) {
 129                         goto out_free;
 130                 }
 131         } else {
 132                 tmp = simple_strtoull(buf, &end, 10);
 133                 if (*end != '\0')
 134                         goto out_free;
 135         }
 136         spin_lock_irqsave(&counter->lock, flags);
 137         val = res_counter_member(counter, member);
 138         *val = tmp;
 139         spin_unlock_irqrestore(&counter->lock, flags);
 140         ret = nbytes;
 141 out_free:
 142         kfree(buf);
 143 out:
 144         return ret;
 145 }