Line data Source code
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 842617 : __percpu_counter_add(fbc, amount, percpu_counter_batch);
48 : }
49 :
50 : static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
51 : {
52 104 : s64 ret = __percpu_counter_sum(fbc);
53 104 : return ret < 0 ? 0 : ret;
54 : }
55 :
56 : static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
57 : {
58 374 : 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 */
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