[linux-block.git] / include / linux / rcu_sync.h

/* SPDX-License-Identifier: GPL-2.0+ */
/*
 * RCU-based infrastructure for lightweight reader-writer locking
 *
 * Copyright (c) 2015, Red Hat, Inc.
 *
 * Author: Oleg Nesterov <oleg@redhat.com>
 */

#ifndef _LINUX_RCU_SYNC_H_
#define _LINUX_RCU_SYNC_H_

#include <linux/wait.h>
#include <linux/rcupdate.h>

enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };

/* Structure to mediate between updaters and fastpath-using readers.  */
struct rcu_sync {
	int			gp_state;
	int			gp_count;
	wait_queue_head_t	gp_wait;

	int			cb_state;
	struct rcu_head		cb_head;

	enum rcu_sync_type	gp_type;
};

extern void rcu_sync_lockdep_assert(struct rcu_sync *);

/**
 * rcu_sync_is_idle() - Are readers permitted to use their fastpaths?
 * @rsp: Pointer to rcu_sync structure to use for synchronization
 *
 * Returns true if readers are permitted to use their fastpaths.
 * Must be invoked within an RCU read-side critical section whose
 * flavor matches that of the rcu_sync struture.
 */
static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
{
#ifdef CONFIG_PROVE_RCU
	rcu_sync_lockdep_assert(rsp);
#endif
	return !rsp->gp_state; /* GP_IDLE */
}

extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type);
extern void rcu_sync_enter_start(struct rcu_sync *);
extern void rcu_sync_enter(struct rcu_sync *);
extern void rcu_sync_exit(struct rcu_sync *);
extern void rcu_sync_dtor(struct rcu_sync *);

#define __RCU_SYNC_INITIALIZER(name, type) {				\
		.gp_state = 0,						\
		.gp_count = 0,						\
		.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait),	\
		.cb_state = 0,						\
		.gp_type = type,					\
	}

#define	__DEFINE_RCU_SYNC(name, type)	\
	struct rcu_sync_struct name = __RCU_SYNC_INITIALIZER(name, type)

#define DEFINE_RCU_SYNC(name)		\
	__DEFINE_RCU_SYNC(name, RCU_SYNC)

#define DEFINE_RCU_SCHED_SYNC(name)	\
	__DEFINE_RCU_SYNC(name, RCU_SCHED_SYNC)

#define DEFINE_RCU_BH_SYNC(name)	\
	__DEFINE_RCU_SYNC(name, RCU_BH_SYNC)

#endif /* _LINUX_RCU_SYNC_H_ */
Commit	Line	Data
a66e0092	1	/* SPDX-License-Identifier: GPL-2.0+ */
cc44ca84 ON	2	/*
	3	* RCU-based infrastructure for lightweight reader-writer locking
	4	*
cc44ca84 ON	5	* Copyright (c) 2015, Red Hat, Inc.
	6	*
	7	* Author: Oleg Nesterov <oleg@redhat.com>
	8	*/
	9
	10	#ifndef _LINUX_RCU_SYNC_H_
	11	#define _LINUX_RCU_SYNC_H_
	12
	13	#include <linux/wait.h>
	14	#include <linux/rcupdate.h>
	15
82e8c565 ON	16	enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };
82e8c565 ON	17
cc44ca84 ON	18	/* Structure to mediate between updaters and fastpath-using readers. */
	19	struct rcu_sync {
	20	int gp_state;
	21	int gp_count;
	22	wait_queue_head_t gp_wait;
	23
	24	int cb_state;
	25	struct rcu_head cb_head;
	26
82e8c565	27	enum rcu_sync_type gp_type;
cc44ca84 ON	28	};
cc44ca84 ON	29
4bace734	30	extern void rcu_sync_lockdep_assert(struct rcu_sync *);
3a518b76	31
cc44ca84 ON	32	/**
	33	* rcu_sync_is_idle() - Are readers permitted to use their fastpaths?
	34	* @rsp: Pointer to rcu_sync structure to use for synchronization
	35	*
	36	* Returns true if readers are permitted to use their fastpaths.
	37	* Must be invoked within an RCU read-side critical section whose
	38	* flavor matches that of the rcu_sync struture.
	39	*/
	40	static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
	41	{
3a518b76	42	#ifdef CONFIG_PROVE_RCU
4bace734	43	rcu_sync_lockdep_assert(rsp);
3a518b76	44	#endif
4bace734	45	return !rsp->gp_state; /* GP_IDLE */
cc44ca84 ON	46	}
cc44ca84 ON	47
cc44ca84	48	extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type);
3942a9bd	49	extern void rcu_sync_enter_start(struct rcu_sync *);
cc44ca84 ON	50	extern void rcu_sync_enter(struct rcu_sync *);
cc44ca84 ON	51	extern void rcu_sync_exit(struct rcu_sync *);
07899a6e	52	extern void rcu_sync_dtor(struct rcu_sync *);
cc44ca84	53
82e8c565 ON	54	#define __RCU_SYNC_INITIALIZER(name, type) { \
	55	.gp_state = 0, \
	56	.gp_count = 0, \
	57	.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \
	58	.cb_state = 0, \
	59	.gp_type = type, \
	60	}
	61
	62	#define __DEFINE_RCU_SYNC(name, type) \
	63	struct rcu_sync_struct name = __RCU_SYNC_INITIALIZER(name, type)
	64
	65	#define DEFINE_RCU_SYNC(name) \
	66	__DEFINE_RCU_SYNC(name, RCU_SYNC)
	67
	68	#define DEFINE_RCU_SCHED_SYNC(name) \
	69	__DEFINE_RCU_SYNC(name, RCU_SCHED_SYNC)
	70
	71	#define DEFINE_RCU_BH_SYNC(name) \
	72	__DEFINE_RCU_SYNC(name, RCU_BH_SYNC)
	73
cc44ca84	74	#endif /* _LINUX_RCU_SYNC_H_ */