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1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef _LINUX_PERCPU_COUNTER_H
3#define _LINUX_PERCPU_COUNTER_H
4/*
5 * A simple "approximate counter" for use in ext2 and ext3 superblocks.
6 *
7 * WARNING: these things are HUGE. 4 kbytes per counter on 32-way P4.
8 */
9
10#include <linux/spinlock.h>
11#include <linux/smp.h>
12#include <linux/list.h>
13#include <linux/threads.h>
14#include <linux/percpu.h>
15#include <linux/types.h>
16#include <linux/gfp.h>
17
18#ifdef CONFIG_SMP
19
20struct percpu_counter {
21 raw_spinlock_t lock;
22 s64 count;
23#ifdef CONFIG_HOTPLUG_CPU
24 struct list_head list; /* All percpu_counters are on a list */
25#endif
26 s32 __percpu *counters;
27};
28
29extern int percpu_counter_batch;
30
31int __percpu_counter_init(struct percpu_counter *fbc, s64 amount, gfp_t gfp,
32 struct lock_class_key *key);
33
34#define percpu_counter_init(fbc, value, gfp) \
35 ({ \
36 static struct lock_class_key __key; \
37 \
38 __percpu_counter_init(fbc, value, gfp, &__key); \
39 })
40
41void percpu_counter_destroy(struct percpu_counter *fbc);
42void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
43void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount,
44 s32 batch);
45s64 __percpu_counter_sum(struct percpu_counter *fbc);
46int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch);
47
48static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
49{
50 return __percpu_counter_compare(fbc, rhs, percpu_counter_batch);
51}
52
53static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
54{
55 percpu_counter_add_batch(fbc, amount, percpu_counter_batch);
56}
57
58static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
59{
60 s64 ret = __percpu_counter_sum(fbc);
61 return ret < 0 ? 0 : ret;
62}
63
64static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
65{
66 return __percpu_counter_sum(fbc);
67}
68
69static inline s64 percpu_counter_read(struct percpu_counter *fbc)
70{
71 return fbc->count;
72}
73
74/*
75 * It is possible for the percpu_counter_read() to return a small negative
76 * number for some counter which should never be negative.
77 *
78 */
79static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
80{
81 s64 ret = fbc->count;
82
83 barrier(); /* Prevent reloads of fbc->count */
84 if (ret >= 0)
85 return ret;
86 return 0;
87}
88
89static inline bool percpu_counter_initialized(struct percpu_counter *fbc)
90{
91 return (fbc->counters != NULL);
92}
93
94#else /* !CONFIG_SMP */
95
96struct percpu_counter {
97 s64 count;
98};
99
100static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount,
101 gfp_t gfp)
102{
103 fbc->count = amount;
104 return 0;
105}
106
107static inline void percpu_counter_destroy(struct percpu_counter *fbc)
108{
109}
110
111static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
112{
113 fbc->count = amount;
114}
115
116static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
117{
118 if (fbc->count > rhs)
119 return 1;
120 else if (fbc->count < rhs)
121 return -1;
122 else
123 return 0;
124}
125
126static inline int
127__percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch)
128{
129 return percpu_counter_compare(fbc, rhs);
130}
131
132static inline void
133percpu_counter_add(struct percpu_counter *fbc, s64 amount)
134{
135 preempt_disable();
136 fbc->count += amount;
137 preempt_enable();
138}
139
140static inline void
141percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch)
142{
143 percpu_counter_add(fbc, amount);
144}
145
146static inline s64 percpu_counter_read(struct percpu_counter *fbc)
147{
148 return fbc->count;
149}
150
151/*
152 * percpu_counter is intended to track positive numbers. In the UP case the
153 * number should never be negative.
154 */
155static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
156{
157 return fbc->count;
158}
159
160static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
161{
162 return percpu_counter_read_positive(fbc);
163}
164
165static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
166{
167 return percpu_counter_read(fbc);
168}
169
170static inline bool percpu_counter_initialized(struct percpu_counter *fbc)
171{
172 return true;
173}
174
175#endif /* CONFIG_SMP */
176
177static inline void percpu_counter_inc(struct percpu_counter *fbc)
178{
179 percpu_counter_add(fbc, 1);
180}
181
182static inline void percpu_counter_dec(struct percpu_counter *fbc)
183{
184 percpu_counter_add(fbc, -1);
185}
186
187static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
188{
189 percpu_counter_add(fbc, -amount);
190}
191
192#endif /* _LINUX_PERCPU_COUNTER_H */