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, struct res_counter *parent)
  19 {
  20         spin_lock_init(&counter->lock);
  21         counter->limit = RESOURCE_MAX;
  22         counter->parent = parent;
  23 }
  24
  25 int res_counter_charge_locked(struct res_counter *counter, unsigned long val)
  26 {
  27         if (counter->usage + val > counter->limit) {
  28                 counter->failcnt++;
  29                 return -ENOMEM;
  30         }
  31
  32         counter->usage += val;
  33         if (counter->usage > counter->max_usage)
  34                 counter->max_usage = counter->usage;
  35         return 0;
  36 }
  37
  38 int res_counter_charge(struct res_counter *counter, unsigned long val,
  39                         struct res_counter **limit_fail_at)
  40 {
  41         int ret;
  42         unsigned long flags;
  43         struct res_counter *c, *u;
  44
  45         *limit_fail_at = NULL;
  46         local_irq_save(flags);
  47         for (c = counter; c != NULL; c = c->parent) {
  48                 spin_lock(&c->lock);
  49                 ret = res_counter_charge_locked(c, val);
  50                 spin_unlock(&c->lock);
  51                 if (ret < 0) {
  52                         *limit_fail_at = c;
  53                         goto undo;
  54                 }
  55         }
  56         ret = 0;
  57         goto done;
  58 undo:
  59         for (u = counter; u != c; u = u->parent) {
  60                 spin_lock(&u->lock);
  61                 res_counter_uncharge_locked(u, val);
  62                 spin_unlock(&u->lock);
  63         }
  64 done:
  65         local_irq_restore(flags);
  66         return ret;
  67 }
  68
  69 void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val)
  70 {
  71         if (WARN_ON(counter->usage < val))
  72                 val = counter->usage;
  73
  74         counter->usage -= val;
  75 }
  76
  77 void res_counter_uncharge(struct res_counter *counter, unsigned long val)
  78 {
  79         unsigned long flags;
  80         struct res_counter *c;
  81
  82         local_irq_save(flags);
  83         for (c = counter; c != NULL; c = c->parent) {
  84                 spin_lock(&c->lock);
  85                 res_counter_uncharge_locked(c, val);
  86                 spin_unlock(&c->lock);
  87         }
  88         local_irq_restore(flags);
  89 }
  90
  91
  92 static inline unsigned long long *
  93 res_counter_member(struct res_counter *counter, int member)
  94 {
  95         switch (member) {
  96         case RES_USAGE:
  97                 return &counter->usage;
  98         case RES_MAX_USAGE:
  99                 return &counter->max_usage;
 100         case RES_LIMIT:
 101                 return &counter->limit;
 102         case RES_FAILCNT:
 103                 return &counter->failcnt;
 104         };
 105
 106         BUG();
 107         return NULL;
 108 }
 109
 110 ssize_t res_counter_read(struct res_counter *counter, int member,
 111                 const char __user *userbuf, size_t nbytes, loff_t *pos,
 112                 int (*read_strategy)(unsigned long long val, char *st_buf))
 113 {
 114         unsigned long long *val;
 115         char buf[64], *s;
 116
 117         s = buf;
 118         val = res_counter_member(counter, member);
 119         if (read_strategy)
 120                 s += read_strategy(*val, s);
 121         else
 122                 s += sprintf(s, "%llu\n", *val);
 123         return simple_read_from_buffer((void __user *)userbuf, nbytes,
 124                         pos, buf, s - buf);
 125 }
 126
 127 u64 res_counter_read_u64(struct res_counter *counter, int member)
 128 {
 129         return *res_counter_member(counter, member);
 130 }
 131
 132 int res_counter_memparse_write_strategy(const char *buf,
 133                                         unsigned long long *res)
 134 {
 135         char *end;
 136
 137         /* return RESOURCE_MAX(unlimited) if "-1" is specified */
 138         if (*buf == '-') {
 139                 *res = simple_strtoull(buf + 1, &end, 10);
 140                 if (*res != 1 || *end != '\0')
 141                         return -EINVAL;
 142                 *res = RESOURCE_MAX;
 143                 return 0;
 144         }
 145
 146         /* FIXME - make memparse() take const char* args */
 147         *res = memparse((char *)buf, &end);
 148         if (*end != '\0')
 149                 return -EINVAL;
 150
 151         *res = PAGE_ALIGN(*res);
 152         return 0;
 153 }
 154
 155 int res_counter_write(struct res_counter *counter, int member,
 156                       const char *buf, write_strategy_fn write_strategy)
 157 {
 158         char *end;
 159         unsigned long flags;
 160         unsigned long long tmp, *val;
 161
 162         if (write_strategy) {
 163                 if (write_strategy(buf, &tmp))
 164                         return -EINVAL;
 165         } else {
 166                 tmp = simple_strtoull(buf, &end, 10);
 167                 if (*end != '\0')
 168                         return -EINVAL;
 169         }
 170         spin_lock_irqsave(&counter->lock, flags);
 171         val = res_counter_member(counter, member);
 172         *val = tmp;
 173         spin_unlock_irqrestore(&counter->lock, flags);
 174         return 0;
 175 }