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/* 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_ */
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