Memory controller: resource counters
[linux-2.6.git] / 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 }