Import Linux's percpu_counter
[akaros.git] / kern / include / percpu_counter.h
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
19 struct 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
28 extern int percpu_counter_batch;
29
30 int __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
40 void percpu_counter_destroy(struct percpu_counter *fbc);
41 void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
42 void percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount,
43                               s32 batch);
44 s64 __percpu_counter_sum(struct percpu_counter *fbc);
45 int __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch);
46
47 static inline int percpu_counter_compare(struct percpu_counter *fbc, s64 rhs)
48 {
49         return __percpu_counter_compare(fbc, rhs, percpu_counter_batch);
50 }
51
52 static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
53 {
54         percpu_counter_add_batch(fbc, amount, percpu_counter_batch);
55 }
56
57 static 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
63 static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
64 {
65         return __percpu_counter_sum(fbc);
66 }
67
68 static 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  */
78 static 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
88 static inline int percpu_counter_initialized(struct percpu_counter *fbc)
89 {
90         return (fbc->counters != NULL);
91 }
92
93 #else /* !CONFIG_SMP */
94
95 struct percpu_counter {
96         s64 count;
97 };
98
99 static 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
106 static inline void percpu_counter_destroy(struct percpu_counter *fbc)
107 {
108 }
109
110 static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
111 {
112         fbc->count = amount;
113 }
114
115 static 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
125 static inline int
126 __percpu_counter_compare(struct percpu_counter *fbc, s64 rhs, s32 batch)
127 {
128         return percpu_counter_compare(fbc, rhs);
129 }
130
131 static inline void
132 percpu_counter_add(struct percpu_counter *fbc, s64 amount)
133 {
134         preempt_disable();
135         fbc->count += amount;
136         preempt_enable();
137 }
138
139 static inline void
140 percpu_counter_add_batch(struct percpu_counter *fbc, s64 amount, s32 batch)
141 {
142         percpu_counter_add(fbc, amount);
143 }
144
145 static 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  */
154 static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
155 {
156         return fbc->count;
157 }
158
159 static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
160 {
161         return percpu_counter_read_positive(fbc);
162 }
163
164 static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
165 {
166         return percpu_counter_read(fbc);
167 }
168
169 static inline int percpu_counter_initialized(struct percpu_counter *fbc)
170 {
171         return 1;
172 }
173
174 #endif  /* CONFIG_SMP */
175
176 static inline void percpu_counter_inc(struct percpu_counter *fbc)
177 {
178         percpu_counter_add(fbc, 1);
179 }
180
181 static inline void percpu_counter_dec(struct percpu_counter *fbc)
182 {
183         percpu_counter_add(fbc, -1);
184 }
185
186 static 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 */