[linux-2.6-block.git] / include / linux / percpu_counter.h

#ifndef _LINUX_PERCPU_COUNTER_H
#define _LINUX_PERCPU_COUNTER_H
/*
 * A simple "approximate counter" for use in ext2 and ext3 superblocks.
 *
 * WARNING: these things are HUGE.  4 kbytes per counter on 32-way P4.
 */

#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/list.h>
#include <linux/threads.h>
#include <linux/percpu.h>
#include <linux/types.h>

#ifdef CONFIG_SMP

struct percpu_counter {
	spinlock_t lock;
	s64 count;
#ifdef CONFIG_HOTPLUG_CPU
	struct list_head list;	/* All percpu_counters are on a list */
#endif
	s32 *counters;
};

extern int percpu_counter_batch;

int __percpu_counter_init(struct percpu_counter *fbc, s64 amount,
			  struct lock_class_key *key);

#define percpu_counter_init(fbc, value)					\
	({								\
		static struct lock_class_key __key;			\
									\
		__percpu_counter_init(fbc, value, &__key);		\
	})

void percpu_counter_destroy(struct percpu_counter *fbc);
void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
s64 __percpu_counter_sum(struct percpu_counter *fbc);

static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
{
	__percpu_counter_add(fbc, amount, percpu_counter_batch);
}

static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
{
	s64 ret = __percpu_counter_sum(fbc);
	return ret < 0 ? 0 : ret;
}

static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
{
	return __percpu_counter_sum(fbc);
}

static inline s64 percpu_counter_read(struct percpu_counter *fbc)
{
	return fbc->count;
}

/*
 * It is possible for the percpu_counter_read() to return a small negative
 * number for some counter which should never be negative.
 *
 */
static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
{
	s64 ret = fbc->count;

	barrier();		/* Prevent reloads of fbc->count */
	if (ret >= 0)
		return ret;
	return 1;
}

#else

struct percpu_counter {
	s64 count;
};

static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount)
{
	fbc->count = amount;
	return 0;
}

static inline void percpu_counter_destroy(struct percpu_counter *fbc)
{
}

static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
{
	fbc->count = amount;
}

#define __percpu_counter_add(fbc, amount, batch) \
	percpu_counter_add(fbc, amount)

static inline void
percpu_counter_add(struct percpu_counter *fbc, s64 amount)
{
	preempt_disable();
	fbc->count += amount;
	preempt_enable();
}

static inline s64 percpu_counter_read(struct percpu_counter *fbc)
{
	return fbc->count;
}

static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
{
	return fbc->count;
}

static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
{
	return percpu_counter_read_positive(fbc);
}

static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
{
	return percpu_counter_read(fbc);
}

#endif	/* CONFIG_SMP */

static inline void percpu_counter_inc(struct percpu_counter *fbc)
{
	percpu_counter_add(fbc, 1);
}

static inline void percpu_counter_dec(struct percpu_counter *fbc)
{
	percpu_counter_add(fbc, -1);
}

static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
{
	percpu_counter_add(fbc, -amount);
}

#endif /* _LINUX_PERCPU_COUNTER_H */
Commit	Line	Data
1da177e4 LT	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
1da177e4 LT	9	#include <linux/spinlock.h>
1da177e4 LT	10	#include <linux/smp.h>
c67ad917	11	#include <linux/list.h>
1da177e4 LT	12	#include <linux/threads.h>
1da177e4 LT	13	#include <linux/percpu.h>
0216bfcf	14	#include <linux/types.h>
1da177e4 LT	15
	16	#ifdef CONFIG_SMP
	17
	18	struct percpu_counter {
	19	spinlock_t lock;
0216bfcf	20	s64 count;
c67ad917 AM	21	#ifdef CONFIG_HOTPLUG_CPU
	22	struct list_head list; /* All percpu_counters are on a list */
	23	#endif
0216bfcf	24	s32 *counters;
1da177e4 LT	25	};
1da177e4 LT	26
179f7ebf	27	extern int percpu_counter_batch;
1da177e4	28
ea319518 PZ	29	int __percpu_counter_init(struct percpu_counter *fbc, s64 amount,
	30	struct lock_class_key *key);
	31
	32	#define percpu_counter_init(fbc, value) \
	33	({ \
	34	static struct lock_class_key __key; \
	35	\
	36	__percpu_counter_init(fbc, value, &__key); \
	37	})
	38
c67ad917	39	void percpu_counter_destroy(struct percpu_counter *fbc);
3a587f47	40	void percpu_counter_set(struct percpu_counter *fbc, s64 amount);
20e89767	41	void __percpu_counter_add(struct percpu_counter *fbc, s64 amount, s32 batch);
02d21168	42	s64 __percpu_counter_sum(struct percpu_counter *fbc);
1da177e4	43
20e89767	44	static inline void percpu_counter_add(struct percpu_counter *fbc, s64 amount)
252e0ba6	45	{
179f7ebf	46	__percpu_counter_add(fbc, amount, percpu_counter_batch);
252e0ba6 PZ	47	}
252e0ba6 PZ	48
bf1d89c8 PZ	49	static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
bf1d89c8 PZ	50	{
02d21168	51	s64 ret = __percpu_counter_sum(fbc);
bf1d89c8 PZ	52	return ret < 0 ? 0 : ret;
	53	}
	54
	55	static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
	56	{
02d21168	57	return __percpu_counter_sum(fbc);
bf1d89c8 PZ	58	}
bf1d89c8 PZ	59
0216bfcf	60	static inline s64 percpu_counter_read(struct percpu_counter *fbc)
1da177e4 LT	61	{
	62	return fbc->count;
	63	}
	64
	65	/*
	66	* It is possible for the percpu_counter_read() to return a small negative
	67	* number for some counter which should never be negative.
0216bfcf	68	*
1da177e4	69	*/
0216bfcf	70	static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
1da177e4	71	{
0216bfcf	72	s64 ret = fbc->count;
1da177e4 LT	73
1da177e4 LT	74	barrier(); /* Prevent reloads of fbc->count */
0216bfcf	75	if (ret >= 0)
1da177e4 LT	76	return ret;
	77	return 1;
	78	}
	79
	80	#else
	81
	82	struct percpu_counter {
0216bfcf	83	s64 count;
1da177e4 LT	84	};
1da177e4 LT	85
833f4077	86	static inline int percpu_counter_init(struct percpu_counter *fbc, s64 amount)
1da177e4	87	{
0216bfcf	88	fbc->count = amount;
833f4077	89	return 0;
1da177e4 LT	90	}
	91
	92	static inline void percpu_counter_destroy(struct percpu_counter *fbc)
	93	{
	94	}
	95
3a587f47 PZ	96	static inline void percpu_counter_set(struct percpu_counter *fbc, s64 amount)
	97	{
	98	fbc->count = amount;
	99	}
	100
252e0ba6 PZ	101	#define __percpu_counter_add(fbc, amount, batch) \
	102	percpu_counter_add(fbc, amount)
	103
1da177e4	104	static inline void
20e89767	105	percpu_counter_add(struct percpu_counter *fbc, s64 amount)
1da177e4 LT	106	{
	107	preempt_disable();
	108	fbc->count += amount;
	109	preempt_enable();
	110	}
	111
0216bfcf	112	static inline s64 percpu_counter_read(struct percpu_counter *fbc)
1da177e4 LT	113	{
	114	return fbc->count;
	115	}
	116
0216bfcf	117	static inline s64 percpu_counter_read_positive(struct percpu_counter *fbc)
1da177e4 LT	118	{
	119	return fbc->count;
	120	}
	121
52d9f3b4	122	static inline s64 percpu_counter_sum_positive(struct percpu_counter *fbc)
e2bab3d9 AM	123	{
	124	return percpu_counter_read_positive(fbc);
	125	}
	126
bf1d89c8 PZ	127	static inline s64 percpu_counter_sum(struct percpu_counter *fbc)
	128	{
	129	return percpu_counter_read(fbc);
	130	}
	131
1da177e4 LT	132	#endif /* CONFIG_SMP */
	133
	134	static inline void percpu_counter_inc(struct percpu_counter *fbc)
	135	{
aa0dff2d	136	percpu_counter_add(fbc, 1);
1da177e4 LT	137	}
	138
	139	static inline void percpu_counter_dec(struct percpu_counter *fbc)
	140	{
aa0dff2d	141	percpu_counter_add(fbc, -1);
1da177e4 LT	142	}
1da177e4 LT	143
3cb4f9fa PZ	144	static inline void percpu_counter_sub(struct percpu_counter *fbc, s64 amount)
	145	{
	146	percpu_counter_add(fbc, -amount);
	147	}
	148
1da177e4	149	#endif /* _LINUX_PERCPU_COUNTER_H */