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1#ifndef __RES_COUNTER_H__
2#define __RES_COUNTER_H__
3
4/*
5 * Resource Counters
6 * Contain common data types and routines for resource accounting
7 *
8 * Copyright 2007 OpenVZ SWsoft Inc
9 *
10 * Author: Pavel Emelianov <xemul@openvz.org>
11 *
12 * See Documentation/cgroups/resource_counter.txt for more
13 * info about what this counter is.
14 */
15
16#include <linux/cgroup.h>
17
18/*
19 * The core object. the cgroup that wishes to account for some
20 * resource may include this counter into its structures and use
21 * the helpers described beyond
22 */
23
24struct res_counter {
25 /*
26 * the current resource consumption level
27 */
28 unsigned long long usage;
29 /*
30 * the maximal value of the usage from the counter creation
31 */
32 unsigned long long max_usage;
33 /*
34 * the limit that usage cannot exceed
35 */
36 unsigned long long limit;
37 /*
38 * the number of unsuccessful attempts to consume the resource
39 */
40 unsigned long long failcnt;
41 /*
42 * the lock to protect all of the above.
43 * the routines below consider this to be IRQ-safe
44 */
45 spinlock_t lock;
46 /*
47 * Parent counter, used for hierarchial resource accounting
48 */
49 struct res_counter *parent;
50};
51
52#define RESOURCE_MAX (unsigned long long)LLONG_MAX
53
54/**
55 * Helpers to interact with userspace
56 * res_counter_read_u64() - returns the value of the specified member.
57 * res_counter_read/_write - put/get the specified fields from the
58 * res_counter struct to/from the user
59 *
60 * @counter: the counter in question
61 * @member: the field to work with (see RES_xxx below)
62 * @buf: the buffer to opeate on,...
63 * @nbytes: its size...
64 * @pos: and the offset.
65 */
66
67u64 res_counter_read_u64(struct res_counter *counter, int member);
68
69ssize_t res_counter_read(struct res_counter *counter, int member,
70 const char __user *buf, size_t nbytes, loff_t *pos,
71 int (*read_strategy)(unsigned long long val, char *s));
72
73typedef int (*write_strategy_fn)(const char *buf, unsigned long long *val);
74
75int res_counter_memparse_write_strategy(const char *buf,
76 unsigned long long *res);
77
78int res_counter_write(struct res_counter *counter, int member,
79 const char *buffer, write_strategy_fn write_strategy);
80
81/*
82 * the field descriptors. one for each member of res_counter
83 */
84
85enum {
86 RES_USAGE,
87 RES_MAX_USAGE,
88 RES_LIMIT,
89 RES_FAILCNT,
90};
91
92/*
93 * helpers for accounting
94 */
95
96void res_counter_init(struct res_counter *counter, struct res_counter *parent);
97
98/*
99 * charge - try to consume more resource.
100 *
101 * @counter: the counter
102 * @val: the amount of the resource. each controller defines its own
103 * units, e.g. numbers, bytes, Kbytes, etc
104 *
105 * returns 0 on success and <0 if the counter->usage will exceed the
106 * counter->limit _locked call expects the counter->lock to be taken
107 */
108
109int __must_check res_counter_charge_locked(struct res_counter *counter,
110 unsigned long val);
111int __must_check res_counter_charge(struct res_counter *counter,
112 unsigned long val, struct res_counter **limit_fail_at);
113
114/*
115 * uncharge - tell that some portion of the resource is released
116 *
117 * @counter: the counter
118 * @val: the amount of the resource
119 *
120 * these calls check for usage underflow and show a warning on the console
121 * _locked call expects the counter->lock to be taken
122 */
123
124void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
125void res_counter_uncharge(struct res_counter *counter, unsigned long val);
126
127static inline bool res_counter_limit_check_locked(struct res_counter *cnt)
128{
129 if (cnt->usage < cnt->limit)
130 return true;
131
132 return false;
133}
134
135/*
136 * Helper function to detect if the cgroup is within it's limit or
137 * not. It's currently called from cgroup_rss_prepare()
138 */
139static inline bool res_counter_check_under_limit(struct res_counter *cnt)
140{
141 bool ret;
142 unsigned long flags;
143
144 spin_lock_irqsave(&cnt->lock, flags);
145 ret = res_counter_limit_check_locked(cnt);
146 spin_unlock_irqrestore(&cnt->lock, flags);
147 return ret;
148}
149
150static inline void res_counter_reset_max(struct res_counter *cnt)
151{
152 unsigned long flags;
153
154 spin_lock_irqsave(&cnt->lock, flags);
155 cnt->max_usage = cnt->usage;
156 spin_unlock_irqrestore(&cnt->lock, flags);
157}
158
159static inline void res_counter_reset_failcnt(struct res_counter *cnt)
160{
161 unsigned long flags;
162
163 spin_lock_irqsave(&cnt->lock, flags);
164 cnt->failcnt = 0;
165 spin_unlock_irqrestore(&cnt->lock, flags);
166}
167
168static inline int res_counter_set_limit(struct res_counter *cnt,
169 unsigned long long limit)
170{
171 unsigned long flags;
172 int ret = -EBUSY;
173
174 spin_lock_irqsave(&cnt->lock, flags);
175 if (cnt->usage <= limit) {
176 cnt->limit = limit;
177 ret = 0;
178 }
179 spin_unlock_irqrestore(&cnt->lock, flags);
180 return ret;
181}
182
183#endif