150 lines
3.2 KiB
C
150 lines
3.2 KiB
C
#ifndef _LINUX_PERCPU_COUNTER_H
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#define _LINUX_PERCPU_COUNTER_H
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/*
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* A simple "approximate counter" for use in ext2 and ext3 superblocks.
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*
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* WARNING: these things are HUGE. 4 kbytes per counter on 32-way P4.
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*/
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#include <linux/spinlock.h>
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#include <linux/smp.h>
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#include <linux/list.h>
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#include <linux/threads.h>
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#include <linux/percpu.h>
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#include <linux/types.h>
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#ifdef CONFIG_SMP
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struct percpu_counter {
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spinlock_t lock;
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s64 count;
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#ifdef CONFIG_HOTPLUG_CPU
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struct list_head list; /* All percpu_counters are on a list */
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#endif
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s32 *counters;
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};
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extern int percpu_counter_batch;
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int __percpu_counter_init(struct percpu_counter *fbc, s64 amount,
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struct lock_class_key *key);
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#define percpu_counter_init(fbc, value) \
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({ \
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static struct lock_class_key __key; \
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\
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__percpu_counter_init(fbc, value, &__key); \
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})
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void percpu_counter_destroy(struct percpu_counter *fbc);
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void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
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void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
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s64 __percpu_counter_sum(struct percpu_counter *fbc);
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static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
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{
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__percpu_counter_add(fbc, amount, percpu_counter_batch);
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}
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static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
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{
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s64 ret = __percpu_counter_sum(fbc);
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return ret < 0 ? 0 : ret;
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}
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static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
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{
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return __percpu_counter_sum(fbc);
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}
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static inline s64 percpu_counter_read(struct percpu_counter *fbc)
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{
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return fbc->count;
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}
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/*
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* It is possible for the percpu_counter_read() to return a small negative
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* number for some counter which should never be negative.
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*
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*/
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static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
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{
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s64 ret = fbc->count;
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barrier(); /* Prevent reloads of fbc->count */
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if (ret >= 0)
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return ret;
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return 1;
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}
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#else
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struct percpu_counter {
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s64 count;
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};
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static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount)
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{
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fbc->count = amount;
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return 0;
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}
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static inline void percpu_counter_destroy(struct percpu_counter *fbc)
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{
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}
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static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
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{
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fbc->count = amount;
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}
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#define __percpu_counter_add(fbc, amount, batch) \
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percpu_counter_add(fbc, amount)
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static inline void
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percpu_counter_add(struct percpu_counter *fbc, s64 amount)
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{
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preempt_disable();
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fbc->count += amount;
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preempt_enable();
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}
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static inline s64 percpu_counter_read(struct percpu_counter *fbc)
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{
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return fbc->count;
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}
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static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
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{
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return fbc->count;
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}
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static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
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{
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return percpu_counter_read_positive(fbc);
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}
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static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
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{
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return percpu_counter_read(fbc);
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}
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#endif /* CONFIG_SMP */
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static inline void percpu_counter_inc(struct percpu_counter *fbc)
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{
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percpu_counter_add(fbc, 1);
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}
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static inline void percpu_counter_dec(struct percpu_counter *fbc)
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{
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percpu_counter_add(fbc, -1);
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}
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static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
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{
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percpu_counter_add(fbc, -amount);
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}
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#endif /* _LINUX_PERCPU_COUNTER_H */
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