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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/**
53 * Helpers to interact with userspace
54 * res_counter_read_u64() - returns the value of the specified member.
55 * res_counter_read/_write - put/get the specified fields from the
56 * res_counter struct to/from the user
57 *
58 * @counter: the counter in question
59 * @member: the field to work with (see RES_xxx below)
60 * @buf: the buffer to opeate on,...
61 * @nbytes: its size...
62 * @pos: and the offset.
63 */
64
65u64 res_counter_read_u64(struct res_counter *counter, int member);
66
67ssize_t res_counter_read(struct res_counter *counter, int member,
68 const char __user *buf, size_t nbytes, loff_t *pos,
69 int (*read_strategy)(unsigned long long val, char *s));
70
71typedef int (*write_strategy_fn)(const char *buf, unsigned long long *val);
72
73int res_counter_memparse_write_strategy(const char *buf,
74 unsigned long long *res);
75
76int res_counter_write(struct res_counter *counter, int member,
77 const char *buffer, write_strategy_fn write_strategy);
78
79/*
80 * the field descriptors. one for each member of res_counter
81 */
82
83enum {
84 RES_USAGE,
85 RES_MAX_USAGE,
86 RES_LIMIT,
87 RES_FAILCNT,
88};
89
90/*
91 * helpers for accounting
92 */
93
94void res_counter_init(struct res_counter *counter, struct res_counter *parent);
95
96/*
97 * charge - try to consume more resource.
98 *
99 * @counter: the counter
100 * @val: the amount of the resource. each controller defines its own
101 * units, e.g. numbers, bytes, Kbytes, etc
102 *
103 * returns 0 on success and <0 if the counter->usage will exceed the
104 * counter->limit _locked call expects the counter->lock to be taken
105 */
106
107int __must_check res_counter_charge_locked(struct res_counter *counter,
108 unsigned long val);
109int __must_check res_counter_charge(struct res_counter *counter,
110 unsigned long val, struct res_counter **limit_fail_at);
111
112/*
113 * uncharge - tell that some portion of the resource is released
114 *
115 * @counter: the counter
116 * @val: the amount of the resource
117 *
118 * these calls check for usage underflow and show a warning on the console
119 * _locked call expects the counter->lock to be taken
120 */
121
122void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
123void res_counter_uncharge(struct res_counter *counter, unsigned long val);
124
125static inline bool res_counter_limit_check_locked(struct res_counter *cnt)
126{
127 if (cnt->usage < cnt->limit)
128 return true;
129
130 return false;
131}
132
133/*
134 * Helper function to detect if the cgroup is within it's limit or
135 * not. It's currently called from cgroup_rss_prepare()
136 */
137static inline bool res_counter_check_under_limit(struct res_counter *cnt)
138{
139 bool ret;
140 unsigned long flags;
141
142 spin_lock_irqsave(&cnt->lock, flags);
143 ret = res_counter_limit_check_locked(cnt);
144 spin_unlock_irqrestore(&cnt->lock, flags);
145 return ret;
146}
147
148static inline void res_counter_reset_max(struct res_counter *cnt)
149{
150 unsigned long flags;
151
152 spin_lock_irqsave(&cnt->lock, flags);
153 cnt->max_usage = cnt->usage;
154 spin_unlock_irqrestore(&cnt->lock, flags);
155}
156
157static inline void res_counter_reset_failcnt(struct res_counter *cnt)
158{
159 unsigned long flags;
160
161 spin_lock_irqsave(&cnt->lock, flags);
162 cnt->failcnt = 0;
163 spin_unlock_irqrestore(&cnt->lock, flags);
164}
165
166static inline int res_counter_set_limit(struct res_counter *cnt,
167 unsigned long long limit)
168{
169 unsigned long flags;
170 int ret = -EBUSY;
171
172 spin_lock_irqsave(&cnt->lock, flags);
173 if (cnt->usage <= limit) {
174 cnt->limit = limit;
175 ret = 0;
176 }
177 spin_unlock_irqrestore(&cnt->lock, flags);
178 return ret;
179}
180
181#endif