[linux-2.6-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>

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

	struct rcu_head		cb_head;
};

/**
 * 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 some flavor of RCU read-side critical section.
 */
static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
{
	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
			 "suspicious rcu_sync_is_idle() usage");
	return !READ_ONCE(rsp->gp_state); /* GP_IDLE */
}

extern void rcu_sync_init(struct rcu_sync *);
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) {					\
		.gp_state = 0,						\
		.gp_count = 0,						\
		.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait),	\
	}

#define	DEFINE_RCU_SYNC(name)	\
	struct rcu_sync name = __RCU_SYNC_INITIALIZER(name)

#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
	16	/* Structure to mediate between updaters and fastpath-using readers. */
	17	struct rcu_sync {
	18	int gp_state;
	19	int gp_count;
	20	wait_queue_head_t gp_wait;
	21
cc44ca84	22	struct rcu_head cb_head;
cc44ca84 ON	23	};
cc44ca84 ON	24
cc44ca84 ON	25	/**
	26	* rcu_sync_is_idle() - Are readers permitted to use their fastpaths?
	27	* @rsp: Pointer to rcu_sync structure to use for synchronization
	28	*
95bf33b5 ON	29	* Returns true if readers are permitted to use their fastpaths. Must be
95bf33b5 ON	30	* invoked within some flavor of RCU read-side critical section.
cc44ca84 ON	31	*/
	32	static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
	33	{
fbab8d67	34	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
95bf33b5	35	"suspicious rcu_sync_is_idle() usage");
89da3b94	36	return !READ_ONCE(rsp->gp_state); /* GP_IDLE */
cc44ca84 ON	37	}
cc44ca84 ON	38
95bf33b5	39	extern void rcu_sync_init(struct rcu_sync *);
3942a9bd	40	extern void rcu_sync_enter_start(struct rcu_sync *);
cc44ca84 ON	41	extern void rcu_sync_enter(struct rcu_sync *);
cc44ca84 ON	42	extern void rcu_sync_exit(struct rcu_sync *);
07899a6e	43	extern void rcu_sync_dtor(struct rcu_sync *);
cc44ca84	44
95bf33b5	45	#define __RCU_SYNC_INITIALIZER(name) { \
82e8c565 ON	46	.gp_state = 0, \
	47	.gp_count = 0, \
	48	.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \
82e8c565 ON	49	}
82e8c565 ON	50
95bf33b5 ON	51	#define DEFINE_RCU_SYNC(name) \
95bf33b5 ON	52	struct rcu_sync name = __RCU_SYNC_INITIALIZER(name)
82e8c565	53
cc44ca84	54	#endif /* _LINUX_RCU_SYNC_H_ */