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/res_counter.h>
  14 #include <linux/uaccess.h>
  15
  16 void res_counter_init(struct res_counter *counter)
  17 {
  18         spin_lock_init(&counter->lock);
  19         counter->limit = (unsigned long)LONG_MAX;
  20 }
  21
  22 int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
  23 {
  24         if (counter->usage + val > counter->limit) {
  25                 counter->failcnt++;
  26                 return -ENOMEM;
  27         }
  28
  29         counter->usage += val;
  30         return 0;
  31 }
  32
  33 int res_counter_charge(struct res_counter *counter, unsigned long val)
  34 {
  35         int ret;
  36         unsigned long flags;
  37
  38         spin_lock_irqsave(&counter->lock, flags);
  39         ret = res_counter_charge_locked(counter, val);
  40         spin_unlock_irqrestore(&counter->lock, flags);
  41         return ret;
  42 }
  43
  44 void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val)
  45 {
  46         if (WARN_ON(counter->usage < val))
  47                 val = counter->usage;
  48
  49         counter->usage -= val;
  50 }
  51
  52 void res_counter_uncharge(struct res_counter *counter, unsigned long val)
  53 {
  54         unsigned long flags;
  55
  56         spin_lock_irqsave(&counter->lock, flags);
  57         res_counter_uncharge_locked(counter, val);
  58         spin_unlock_irqrestore(&counter->lock, flags);
  59 }
  60
  61
  62 static inline unsigned long *res_counter_member(struct res_counter *counter,
  63                                                 int member)
  64 {
  65         switch (member) {
  66         case RES_USAGE:
  67                 return &counter->usage;
  68         case RES_LIMIT:
  69                 return &counter->limit;
  70         case RES_FAILCNT:
  71                 return &counter->failcnt;
  72         };
  73
  74         BUG();
  75         return NULL;
  76 }
  77
  78 ssize_t res_counter_read(struct res_counter *counter, int member,
  79                 const char __user *userbuf, size_t nbytes, loff_t *pos)
  80 {
  81         unsigned long *val;
  82         char buf[64], *s;
  83
  84         s = buf;
  85         val = res_counter_member(counter, member);
  86         s += sprintf(s, "%lu\n", *val);
  87         return simple_read_from_buffer((void __user *)userbuf, nbytes,
  88                         pos, buf, s - buf);
  89 }
  90
  91 ssize_t res_counter_write(struct res_counter *counter, int member,
  92                 const char __user *userbuf, size_t nbytes, loff_t *pos)
  93 {
  94         int ret;
  95         char *buf, *end;
  96         unsigned long tmp, *val;
  97
  98         buf = kmalloc(nbytes + 1, GFP_KERNEL);
  99         ret = -ENOMEM;
 100         if (buf == NULL)
 101                 goto out;
 102
 103         buf[nbytes] = '\0';
 104         ret = -EFAULT;
 105         if (copy_from_user(buf, userbuf, nbytes))
 106                 goto out_free;
 107
 108         ret = -EINVAL;
 109         tmp = simple_strtoul(buf, &end, 10);
 110         if (*end != '\0')
 111                 goto out_free;
 112
 113         val = res_counter_member(counter, member);
 114         *val = tmp;
 115         ret = nbytes;
 116 out_free:
 117         kfree(buf);
 118 out:
 119         return ret;
 120 }