[fio.git] / lib / seqlock.h

#ifndef FIO_SEQLOCK_H
#define FIO_SEQLOCK_H

#include "types.h"
#include "../arch/arch.h"

struct seqlock {
	volatile unsigned int sequence;
};

static inline void seqlock_init(struct seqlock *s)
{
	s->sequence = 0;
}

static inline unsigned int read_seqlock_begin(struct seqlock *s)
{
	unsigned int seq;

	do {
		seq = atomic_load_acquire(&s->sequence);
		if (!(seq & 1))
			break;
		nop;
	} while (1);

	return seq;
}

static inline bool read_seqlock_retry(struct seqlock *s, unsigned int seq)
{
	read_barrier();
	return s->sequence != seq;
}

static inline void write_seqlock_begin(struct seqlock *s)
{
	s->sequence = atomic_load_acquire(&s->sequence) + 1;
}

static inline void write_seqlock_end(struct seqlock *s)
{
	atomic_store_release(&s->sequence, s->sequence + 1);
}

#endif
Commit	Line	Data
c6bb62bc JA	1	#ifndef FIO_SEQLOCK_H
	2	#define FIO_SEQLOCK_H
	3
64dbaa7e	4	#include "types.h"
c6bb62bc JA	5	#include "../arch/arch.h"
	6
	7	struct seqlock {
ecba19b6	8	volatile unsigned int sequence;
c6bb62bc JA	9	};
	10
	11	static inline void seqlock_init(struct seqlock *s)
	12	{
	13	s->sequence = 0;
	14	}
	15
	16	static inline unsigned int read_seqlock_begin(struct seqlock *s)
	17	{
	18	unsigned int seq;
	19
	20	do {
5fa0c063	21	seq = atomic_load_acquire(&s->sequence);
c6bb62bc JA	22	if (!(seq & 1))
	23	break;
	24	nop;
	25	} while (1);
	26
c6bb62bc JA	27	return seq;
	28	}
	29
	30	static inline bool read_seqlock_retry(struct seqlock *s, unsigned int seq)
	31	{
	32	read_barrier();
	33	return s->sequence != seq;
	34	}
	35
	36	static inline void write_seqlock_begin(struct seqlock *s)
	37	{
5fa0c063	38	s->sequence = atomic_load_acquire(&s->sequence) + 1;
c6bb62bc JA	39	}
	40
	41	static inline void write_seqlock_end(struct seqlock *s)
	42	{
5fa0c063	43	atomic_store_release(&s->sequence, s->sequence + 1);
c6bb62bc JA	44	}
	45
	46	#endif