Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/dtor/input
[linux-2.6-microblaze.git] / include / linux / percpu_counter.h
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
20 struct 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
29 extern int percpu_counter_batch;
30
31 int __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
41 void percpu_counter_destroy(struct percpu_counter *fbc);
42 void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
43 void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount,
44                               s32 batch);
45 s64 __percpu_counter_sum(struct percpu_counter *fbc);
46 int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch);
47 void percpu_counter_sync(struct percpu_counter *fbc);
48
49 static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
50 {
51         return __percpu_counter_compare(fbc, rhs, percpu_counter_batch);
52 }
53
54 static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
55 {
56         percpu_counter_add_batch(fbc, amount, percpu_counter_batch);
57 }
58
59 static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
60 {
61         s64 ret = __percpu_counter_sum(fbc);
62         return ret < 0 ? 0 : ret;
63 }
64
65 static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
66 {
67         return __percpu_counter_sum(fbc);
68 }
69
70 static inline s64 percpu_counter_read(struct percpu_counter *fbc)
71 {
72         return fbc->count;
73 }
74
75 /*
76  * It is possible for the percpu_counter_read() to return a small negative
77  * number for some counter which should never be negative.
78  *
79  */
80 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
81 {
82         /* Prevent reloads of fbc->count */
83         s64 ret = READ_ONCE(fbc->count);
84
85         if (ret >= 0)
86                 return ret;
87         return 0;
88 }
89
90 static inline bool percpu_counter_initialized(struct percpu_counter *fbc)
91 {
92         return (fbc->counters != NULL);
93 }
94
95 #else /* !CONFIG_SMP */
96
97 struct percpu_counter {
98         s64 count;
99 };
100
101 static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount,
102                                       gfp_t gfp)
103 {
104         fbc->count = amount;
105         return 0;
106 }
107
108 static inline void percpu_counter_destroy(struct percpu_counter *fbc)
109 {
110 }
111
112 static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
113 {
114         fbc->count = amount;
115 }
116
117 static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
118 {
119         if (fbc->count > rhs)
120                 return 1;
121         else if (fbc->count < rhs)
122                 return -1;
123         else
124                 return 0;
125 }
126
127 static inline int
128 __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch)
129 {
130         return percpu_counter_compare(fbc, rhs);
131 }
132
133 static inline void
134 percpu_counter_add(struct percpu_counter *fbc, s64 amount)
135 {
136         preempt_disable();
137         fbc->count += amount;
138         preempt_enable();
139 }
140
141 static inline void
142 percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch)
143 {
144         percpu_counter_add(fbc, amount);
145 }
146
147 static inline s64 percpu_counter_read(struct percpu_counter *fbc)
148 {
149         return fbc->count;
150 }
151
152 /*
153  * percpu_counter is intended to track positive numbers. In the UP case the
154  * number should never be negative.
155  */
156 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
157 {
158         return fbc->count;
159 }
160
161 static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
162 {
163         return percpu_counter_read_positive(fbc);
164 }
165
166 static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
167 {
168         return percpu_counter_read(fbc);
169 }
170
171 static inline bool percpu_counter_initialized(struct percpu_counter *fbc)
172 {
173         return true;
174 }
175
176 static inline void percpu_counter_sync(struct percpu_counter *fbc)
177 {
178 }
179 #endif  /* CONFIG_SMP */
180
181 static inline void percpu_counter_inc(struct percpu_counter *fbc)
182 {
183         percpu_counter_add(fbc, 1);
184 }
185
186 static inline void percpu_counter_dec(struct percpu_counter *fbc)
187 {
188         percpu_counter_add(fbc, -1);
189 }
190
191 static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
192 {
193         percpu_counter_add(fbc, -amount);
194 }
195
196 #endif /* _LINUX_PERCPU_COUNTER_H */