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/*
* 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 <[email protected]>
*/
#ifndef _LINUX_RCU_SYNC_H_
#define _LINUX_RCU_SYNC_H_
#include <linux/wait.h>
#include <linux/rcupdate.h>
#include <linux/rh_kabi.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;
RH_KABI_DEPRECATE(int, cb_state)
struct rcu_head cb_head;
RH_KABI_DEPRECATE(enum rcu_sync_type, gp_type)
};
/**
* 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_ */