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