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
24 struct 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 limit that usage can be exceed
39 */
40 unsigned long long soft_limit;
41 /*
42 * the number of unsuccessful attempts to consume the resource
43 */
44 unsigned long long failcnt;
45 /*
46 * the lock to protect all of the above.
47 * the routines below consider this to be IRQ-safe
48 */
49 spinlock_t lock;
50 /*
51 * Parent counter, used for hierarchial resource accounting
52 */
53 struct res_counter *parent;
54 };
55
56 #define RESOURCE_MAX (unsigned long long)LLONG_MAX
57
58 /**
59 * Helpers to interact with userspace
60 * res_counter_read_u64() - returns the value of the specified member.
61 * res_counter_read/_write - put/get the specified fields from the
62 * res_counter struct to/from the user
63 *
64 * @counter: the counter in question
65 * @member: the field to work with (see RES_xxx below)
66 * @buf: the buffer to opeate on,...
67 * @nbytes: its size...
68 * @pos: and the offset.
69 */
70
71 u64 res_counter_read_u64(struct res_counter *counter, int member);
72
73 ssize_t res_counter_read(struct res_counter *counter, int member,
74 const char __user *buf, size_t nbytes, loff_t *pos,
75 int (*read_strategy)(unsigned long long val, char *s));
76
77 typedef int (*write_strategy_fn)(const char *buf, unsigned long long *val);
78
79 int res_counter_memparse_write_strategy(const char *buf,
80 unsigned long long *res);
81
82 int res_counter_write(struct res_counter *counter, int member,
83 const char *buffer, write_strategy_fn write_strategy);
84
85 /*
86 * the field descriptors. one for each member of res_counter
87 */
88
89 enum {
90 RES_USAGE,
91 RES_MAX_USAGE,
92 RES_LIMIT,
93 RES_FAILCNT,
94 RES_SOFT_LIMIT,
95 };
96
97 /*
98 * helpers for accounting
99 */
100
101 void res_counter_init(struct res_counter *counter, struct res_counter *parent);
102
103 /*
104 * charge - try to consume more resource.
105 *
106 * @counter: the counter
107 * @val: the amount of the resource. each controller defines its own
108 * units, e.g. numbers, bytes, Kbytes, etc
109 *
110 * returns 0 on success and <0 if the counter->usage will exceed the
111 * counter->limit _locked call expects the counter->lock to be taken
112 */
113
114 int __must_check res_counter_charge_locked(struct res_counter *counter,
115 unsigned long val);
116 int __must_check res_counter_charge(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 * _locked call expects the counter->lock to be taken
127 */
128
129 void res_counter_uncharge_locked(struct res_counter *counter, unsigned long val);
130 void res_counter_uncharge(struct res_counter *counter, unsigned long val);
131
132 /**
133 * res_counter_margin - calculate chargeable space of a counter
134 * @cnt: the counter
135 *
136 * Returns the difference between the hard limit and the current usage
137 * of resource counter @cnt.
138 */
res_counter_margin(struct res_counter * cnt)139 static inline unsigned long long res_counter_margin(struct res_counter *cnt)
140 {
141 unsigned long long margin;
142 unsigned long flags;
143
144 spin_lock_irqsave(&cnt->lock, flags);
145 margin = cnt->limit - cnt->usage;
146 spin_unlock_irqrestore(&cnt->lock, flags);
147 return margin;
148 }
149
150 /**
151 * Get the difference between the usage and the soft limit
152 * @cnt: The counter
153 *
154 * Returns 0 if usage is less than or equal to soft limit
155 * The difference between usage and soft limit, otherwise.
156 */
157 static inline unsigned long long
res_counter_soft_limit_excess(struct res_counter * cnt)158 res_counter_soft_limit_excess(struct res_counter *cnt)
159 {
160 unsigned long long excess;
161 unsigned long flags;
162
163 spin_lock_irqsave(&cnt->lock, flags);
164 if (cnt->usage <= cnt->soft_limit)
165 excess = 0;
166 else
167 excess = cnt->usage - cnt->soft_limit;
168 spin_unlock_irqrestore(&cnt->lock, flags);
169 return excess;
170 }
171
res_counter_reset_max(struct res_counter * cnt)172 static inline void res_counter_reset_max(struct res_counter *cnt)
173 {
174 unsigned long flags;
175
176 spin_lock_irqsave(&cnt->lock, flags);
177 cnt->max_usage = cnt->usage;
178 spin_unlock_irqrestore(&cnt->lock, flags);
179 }
180
res_counter_reset_failcnt(struct res_counter * cnt)181 static inline void res_counter_reset_failcnt(struct res_counter *cnt)
182 {
183 unsigned long flags;
184
185 spin_lock_irqsave(&cnt->lock, flags);
186 cnt->failcnt = 0;
187 spin_unlock_irqrestore(&cnt->lock, flags);
188 }
189
res_counter_set_limit(struct res_counter * cnt,unsigned long long limit)190 static inline int res_counter_set_limit(struct res_counter *cnt,
191 unsigned long long limit)
192 {
193 unsigned long flags;
194 int ret = -EBUSY;
195
196 spin_lock_irqsave(&cnt->lock, flags);
197 if (cnt->usage <= limit) {
198 cnt->limit = limit;
199 ret = 0;
200 }
201 spin_unlock_irqrestore(&cnt->lock, flags);
202 return ret;
203 }
204
205 static inline int
res_counter_set_soft_limit(struct res_counter * cnt,unsigned long long soft_limit)206 res_counter_set_soft_limit(struct res_counter *cnt,
207 unsigned long long soft_limit)
208 {
209 unsigned long flags;
210
211 spin_lock_irqsave(&cnt->lock, flags);
212 cnt->soft_limit = soft_limit;
213 spin_unlock_irqrestore(&cnt->lock, flags);
214 return 0;
215 }
216
217 #endif
218