res_counter.c revision 0eea10301708c64a6b793894c156e21ddd15eb64 
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
16void res_counter_init(struct res_counter *counter)
17{
18	spin_lock_init(&counter->lock);
19	counter->limit = (unsigned long long)LLONG_MAX;
20}
21
22int 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
33int 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
44void 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
52void 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
62static inline unsigned long long *
63res_counter_member(struct res_counter *counter, 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
78ssize_t res_counter_read(struct res_counter *counter, int member,
79		const char __user *userbuf, size_t nbytes, loff_t *pos,
80		int (*read_strategy)(unsigned long long val, char *st_buf))
81{
82	unsigned long long *val;
83	char buf[64], *s;
84
85	s = buf;
86	val = res_counter_member(counter, member);
87	if (read_strategy)
88		s += read_strategy(*val, s);
89	else
90		s += sprintf(s, "%llu\n", *val);
91	return simple_read_from_buffer((void __user *)userbuf, nbytes,
92			pos, buf, s - buf);
93}
94
95ssize_t res_counter_write(struct res_counter *counter, int member,
96		const char __user *userbuf, size_t nbytes, loff_t *pos,
97		int (*write_strategy)(char *st_buf, unsigned long long *val))
98{
99	int ret;
100	char *buf, *end;
101	unsigned long flags;
102	unsigned long long tmp, *val;
103
104	buf = kmalloc(nbytes + 1, GFP_KERNEL);
105	ret = -ENOMEM;
106	if (buf == NULL)
107		goto out;
108
109	buf[nbytes] = '\0';
110	ret = -EFAULT;
111	if (copy_from_user(buf, userbuf, nbytes))
112		goto out_free;
113
114	ret = -EINVAL;
115
116	if (write_strategy) {
117		if (write_strategy(buf, &tmp)) {
118			goto out_free;
119		}
120	} else {
121		tmp = simple_strtoull(buf, &end, 10);
122		if (*end != '\0')
123			goto out_free;
124	}
125	spin_lock_irqsave(&counter->lock, flags);
126	val = res_counter_member(counter, member);
127	*val = tmp;
128	spin_unlock_irqrestore(&counter->lock, flags);
129	ret = nbytes;
130out_free:
131	kfree(buf);
132out:
133	return ret;
134}
135