[mirror_ubuntu-bionic-kernel.git] / include / linux / rcu_sync.h

/*
 * RCU-based infrastructure for lightweight reader-writer locking
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you can access it online at
 * http://www.gnu.org/licenses/gpl-2.0.html.
 *
 * 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
cc44ca84 ON	1	/*
	2	* RCU-based infrastructure for lightweight reader-writer locking
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License as published by
	6	* the Free Software Foundation; either version 2 of the License, or
	7	* (at your option) any later version.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; if not, you can access it online at
	16	* http://www.gnu.org/licenses/gpl-2.0.html.
	17	*
	18	* Copyright (c) 2015, Red Hat, Inc.
	19	*
	20	* Author: Oleg Nesterov <oleg@redhat.com>
	21	*/
	22
	23	#ifndef _LINUX_RCU_SYNC_H_
	24	#define _LINUX_RCU_SYNC_H_
	25
	26	#include <linux/wait.h>
	27	#include <linux/rcupdate.h>
	28
82e8c565 ON	29	enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };
82e8c565 ON	30
cc44ca84 ON	31	/* Structure to mediate between updaters and fastpath-using readers. */
	32	struct rcu_sync {
	33	int gp_state;
	34	int gp_count;
	35	wait_queue_head_t gp_wait;
	36
	37	int cb_state;
	38	struct rcu_head cb_head;
	39
82e8c565	40	enum rcu_sync_type gp_type;
cc44ca84 ON	41	};
cc44ca84 ON	42
4bace734	43	extern void rcu_sync_lockdep_assert(struct rcu_sync *);
3a518b76	44
cc44ca84 ON	45	/**
	46	* rcu_sync_is_idle() - Are readers permitted to use their fastpaths?
	47	* @rsp: Pointer to rcu_sync structure to use for synchronization
	48	*
	49	* Returns true if readers are permitted to use their fastpaths.
	50	* Must be invoked within an RCU read-side critical section whose
	51	* flavor matches that of the rcu_sync struture.
	52	*/
	53	static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
	54	{
3a518b76	55	#ifdef CONFIG_PROVE_RCU
4bace734	56	rcu_sync_lockdep_assert(rsp);
3a518b76	57	#endif
4bace734	58	return !rsp->gp_state; /* GP_IDLE */
cc44ca84 ON	59	}
cc44ca84 ON	60
cc44ca84	61	extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type);
3942a9bd	62	extern void rcu_sync_enter_start(struct rcu_sync *);
cc44ca84 ON	63	extern void rcu_sync_enter(struct rcu_sync *);
cc44ca84 ON	64	extern void rcu_sync_exit(struct rcu_sync *);
07899a6e	65	extern void rcu_sync_dtor(struct rcu_sync *);
cc44ca84	66
82e8c565 ON	67	#define __RCU_SYNC_INITIALIZER(name, type) { \
	68	.gp_state = 0, \
	69	.gp_count = 0, \
	70	.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \
	71	.cb_state = 0, \
	72	.gp_type = type, \
	73	}
	74
	75	#define __DEFINE_RCU_SYNC(name, type) \
	76	struct rcu_sync_struct name = __RCU_SYNC_INITIALIZER(name, type)
	77
	78	#define DEFINE_RCU_SYNC(name) \
	79	__DEFINE_RCU_SYNC(name, RCU_SYNC)
	80
	81	#define DEFINE_RCU_SCHED_SYNC(name) \
	82	__DEFINE_RCU_SYNC(name, RCU_SCHED_SYNC)
	83
	84	#define DEFINE_RCU_BH_SYNC(name) \
	85	__DEFINE_RCU_SYNC(name, RCU_BH_SYNC)
	86
cc44ca84	87	#endif /* _LINUX_RCU_SYNC_H_ */