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