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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/spinlock.h>
17#include <linux/errno.h>
18
19/*
20 * The core object. the cgroup that wishes to account for some
21 * resource may include this counter into its structures and use
22 * the helpers described beyond
23 */
24
25struct res_counter {
26 /*
27 * the current resource consumption level
28 */
29 unsigned long long usage;
30 /*
31 * the maximal value of the usage from the counter creation
32 */
33 unsigned long long max_usage;
34 /*
35 * the limit that usage cannot exceed
36 */
37 unsigned long long limit;
38 /*
39 * the limit that usage can be exceed
40 */
41 unsigned long long soft_limit;
42 /*
43 * the number of unsuccessful attempts to consume the resource
44 */
45 unsigned long long failcnt;
46 /*
47 * the lock to protect all of the above.
48 * the routines below consider this to be IRQ-safe
49 */
50 spinlock_t lock;
51 /*
52 * Parent counter, used for hierarchial resource accounting
53 */
54 struct res_counter *parent;
55};
56
57#define RES_COUNTER_MAX ULLONG_MAX
58
59/**
60 * Helpers to interact with userspace
61 * res_counter_read_u64() - returns the value of the specified member.
62 * res_counter_read/_write - put/get the specified fields from the
63 * res_counter struct to/from the user
64 *
65 * @counter: the counter in question
66 * @member: the field to work with (see RES_xxx below)
67 * @buf: the buffer to opeate on,...
68 * @nbytes: its size...
69 * @pos: and the offset.
70 */
71
72u64 res_counter_read_u64(struct res_counter *counter, int member);
73
74ssize_t res_counter_read(struct res_counter *counter, int member,
75 const char __user *buf, size_t nbytes, loff_t *pos,
76 int (*read_strategy)(unsigned long long val, char *s));
77
78int res_counter_memparse_write_strategy(const char *buf,
79 unsigned long long *res);
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 RES_SOFT_LIMIT,
91};
92
93/*
94 * helpers for accounting
95 */
96
97void res_counter_init(struct res_counter *counter, struct res_counter *parent);
98
99/*
100 * charge - try to consume more resource.
101 *
102 * @counter: the counter
103 * @val: the amount of the resource. each controller defines its own
104 * units, e.g. numbers, bytes, Kbytes, etc
105 *
106 * returns 0 on success and <0 if the counter->usage will exceed the
107 * counter->limit
108 *
109 * charge_nofail works the same, except that it charges the resource
110 * counter unconditionally, and returns < 0 if the after the current
111 * charge we are over limit.
112 */
113
114int __must_check res_counter_charge(struct res_counter *counter,
115 unsigned long val, struct res_counter **limit_fail_at);
116int res_counter_charge_nofail(struct res_counter *counter,
117 unsigned long val, struct res_counter **limit_fail_at);
118
119/*
120 * uncharge - tell that some portion of the resource is released
121 *
122 * @counter: the counter
123 * @val: the amount of the resource
124 *
125 * these calls check for usage underflow and show a warning on the console
126 *
127 * returns the total charges still present in @counter.
128 */
129
130u64 res_counter_uncharge(struct res_counter *counter, unsigned long val);
131
132u64 res_counter_uncharge_until(struct res_counter *counter,
133 struct res_counter *top,
134 unsigned long val);
135/**
136 * res_counter_margin - calculate chargeable space of a counter
137 * @cnt: the counter
138 *
139 * Returns the difference between the hard limit and the current usage
140 * of resource counter @cnt.
141 */
142static inline unsigned long long res_counter_margin(struct res_counter *cnt)
143{
144 unsigned long long margin;
145 unsigned long flags;
146
147 spin_lock_irqsave(&cnt->lock, flags);
148 if (cnt->limit > cnt->usage)
149 margin = cnt->limit - cnt->usage;
150 else
151 margin = 0;
152 spin_unlock_irqrestore(&cnt->lock, flags);
153 return margin;
154}
155
156/**
157 * Get the difference between the usage and the soft limit
158 * @cnt: The counter
159 *
160 * Returns 0 if usage is less than or equal to soft limit
161 * The difference between usage and soft limit, otherwise.
162 */
163static inline unsigned long long
164res_counter_soft_limit_excess(struct res_counter *cnt)
165{
166 unsigned long long excess;
167 unsigned long flags;
168
169 spin_lock_irqsave(&cnt->lock, flags);
170 if (cnt->usage <= cnt->soft_limit)
171 excess = 0;
172 else
173 excess = cnt->usage - cnt->soft_limit;
174 spin_unlock_irqrestore(&cnt->lock, flags);
175 return excess;
176}
177
178static inline void res_counter_reset_max(struct res_counter *cnt)
179{
180 unsigned long flags;
181
182 spin_lock_irqsave(&cnt->lock, flags);
183 cnt->max_usage = cnt->usage;
184 spin_unlock_irqrestore(&cnt->lock, flags);
185}
186
187static inline void res_counter_reset_failcnt(struct res_counter *cnt)
188{
189 unsigned long flags;
190
191 spin_lock_irqsave(&cnt->lock, flags);
192 cnt->failcnt = 0;
193 spin_unlock_irqrestore(&cnt->lock, flags);
194}
195
196static inline int res_counter_set_limit(struct res_counter *cnt,
197 unsigned long long limit)
198{
199 unsigned long flags;
200 int ret = -EBUSY;
201
202 spin_lock_irqsave(&cnt->lock, flags);
203 if (cnt->usage <= limit) {
204 cnt->limit = limit;
205 ret = 0;
206 }
207 spin_unlock_irqrestore(&cnt->lock, flags);
208 return ret;
209}
210
211static inline int
212res_counter_set_soft_limit(struct res_counter *cnt,
213 unsigned long long soft_limit)
214{
215 unsigned long flags;
216
217 spin_lock_irqsave(&cnt->lock, flags);
218 cnt->soft_limit = soft_limit;
219 spin_unlock_irqrestore(&cnt->lock, flags);
220 return 0;
221}
222
223#endif