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1#ifndef _LINUX_PERCPU_COUNTER_H
2#define _LINUX_PERCPU_COUNTER_H
3/*
4 * A simple "approximate counter" for use in ext2 and ext3 superblocks.
5 *
6 * WARNING: these things are HUGE. 4 kbytes per counter on 32-way P4.
7 */
8
9#include <linux/spinlock.h>
10#include <linux/smp.h>
11#include <linux/list.h>
12#include <linux/threads.h>
13#include <linux/percpu.h>
14#include <linux/types.h>
15#include <linux/gfp.h>
16
17#ifdef CONFIG_SMP
18
19struct percpu_counter {
20 raw_spinlock_t lock;
21 s64 count;
22#ifdef CONFIG_HOTPLUG_CPU
23 struct list_head list; /* All percpu_counters are on a list */
24#endif
25 s32 __percpu *counters;
26};
27
28extern int percpu_counter_batch;
29
30int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp,
31 struct lock_class_key *key);
32
33#define percpu_counter_init(fbc, value, gfp) \
34 ({ \
35 static struct lock_class_key __key; \
36 \
37 __percpu_counter_init(fbc, value, gfp, &__key); \
38 })
39
40void percpu_counter_destroy(struct percpu_counter *fbc);
41void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
42void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount,
43 s32 batch);
44s64 __percpu_counter_sum(struct percpu_counter *fbc);
45int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch);
46
47static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
48{
49 return __percpu_counter_compare(fbc, rhs, percpu_counter_batch);
50}
51
52static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
53{
54 percpu_counter_add_batch(fbc, amount, percpu_counter_batch);
55}
56
57static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
58{
59 s64 ret = __percpu_counter_sum(fbc);
60 return ret < 0 ? 0 : ret;
61}
62
63static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
64{
65 return __percpu_counter_sum(fbc);
66}
67
68static inline s64 percpu_counter_read(struct percpu_counter *fbc)
69{
70 return fbc->count;
71}
72
73/*
74 * It is possible for the percpu_counter_read() to return a small negative
75 * number for some counter which should never be negative.
76 *
77 */
78static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
79{
80 s64 ret = fbc->count;
81
82 barrier(); /* Prevent reloads of fbc->count */
83 if (ret >= 0)
84 return ret;
85 return 0;
86}
87
88static inline int percpu_counter_initialized(struct percpu_counter *fbc)
89{
90 return (fbc->counters != NULL);
91}
92
93#else /* !CONFIG_SMP */
94
95struct percpu_counter {
96 s64 count;
97};
98
99static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount,
100 gfp_t gfp)
101{
102 fbc->count = amount;
103 return 0;
104}
105
106static inline void percpu_counter_destroy(struct percpu_counter *fbc)
107{
108}
109
110static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
111{
112 fbc->count = amount;
113}
114
115static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
116{
117 if (fbc->count > rhs)
118 return 1;
119 else if (fbc->count < rhs)
120 return -1;
121 else
122 return 0;
123}
124
125static inline int
126__percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch)
127{
128 return percpu_counter_compare(fbc, rhs);
129}
130
131static inline void
132percpu_counter_add(struct percpu_counter *fbc, s64 amount)
133{
134 preempt_disable();
135 fbc->count += amount;
136 preempt_enable();
137}
138
139static inline void
140percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch)
141{
142 percpu_counter_add(fbc, amount);
143}
144
145static inline s64 percpu_counter_read(struct percpu_counter *fbc)
146{
147 return fbc->count;
148}
149
150/*
151 * percpu_counter is intended to track positive numbers. In the UP case the
152 * number should never be negative.
153 */
154static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
155{
156 return fbc->count;
157}
158
159static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
160{
161 return percpu_counter_read_positive(fbc);
162}
163
164static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
165{
166 return percpu_counter_read(fbc);
167}
168
169static inline int percpu_counter_initialized(struct percpu_counter *fbc)
170{
171 return 1;
172}
173
174#endif /* CONFIG_SMP */
175
176static inline void percpu_counter_inc(struct percpu_counter *fbc)
177{
178 percpu_counter_add(fbc, 1);
179}
180
181static inline void percpu_counter_dec(struct percpu_counter *fbc)
182{
183 percpu_counter_add(fbc, -1);
184}
185
186static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
187{
188 percpu_counter_add(fbc, -amount);
189}
190
191#endif /* _LINUX_PERCPU_COUNTER_H */