1/* SPDX-License-Identifier: GPL-2.0+ */
 2/*
 3 * RCU-based infrastructure for lightweight reader-writer locking
 4 *
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 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.  */
17struct rcu_sync {
18	int			gp_state;
19	int			gp_count;
20	wait_queue_head_t	gp_wait;
21
 
22	struct rcu_head		cb_head;
 
 
23};
24
 
 
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 *
29 * Returns true if readers are permitted to use their fastpaths.  Must be
30 * invoked within some flavor of RCU read-side critical section.
 
31 */
32static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
33{
34	RCU_LOCKDEP_WARN(!rcu_read_lock_any_held(),
35			 "suspicious rcu_sync_is_idle() usage");
36	return !READ_ONCE(rsp->gp_state); /* GP_IDLE */
 
37}
38
39extern void rcu_sync_init(struct rcu_sync *);
40extern void rcu_sync_enter_start(struct rcu_sync *);
41extern void rcu_sync_enter(struct rcu_sync *);
42extern void rcu_sync_exit(struct rcu_sync *);
43extern void rcu_sync_dtor(struct rcu_sync *);
44
45#define __RCU_SYNC_INITIALIZER(name) {					\
46		.gp_state = 0,						\
47		.gp_count = 0,						\
48		.gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait),	\
 
 
49	}
50
51#define	DEFINE_RCU_SYNC(name)	\
52	struct rcu_sync name = __RCU_SYNC_INITIALIZER(name)
 
 
 
 
 
 
 
 
 
53
54#endif /* _LINUX_RCU_SYNC_H_ */

 
 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
29enum rcu_sync_type { RCU_SYNC, RCU_SCHED_SYNC, RCU_BH_SYNC };
30
31/* Structure to mediate between updaters and fastpath-using readers.  */
32struct 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
40	enum rcu_sync_type	gp_type;
41};
42
43extern void rcu_sync_lockdep_assert(struct rcu_sync *);
44
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 */
53static inline bool rcu_sync_is_idle(struct rcu_sync *rsp)
54{
55#ifdef CONFIG_PROVE_RCU
56	rcu_sync_lockdep_assert(rsp);
57#endif
58	return !rsp->gp_state; /* GP_IDLE */
59}
60
61extern void rcu_sync_init(struct rcu_sync *, enum rcu_sync_type);
62extern void rcu_sync_enter_start(struct rcu_sync *);
63extern void rcu_sync_enter(struct rcu_sync *);
64extern void rcu_sync_exit(struct rcu_sync *);
65extern void rcu_sync_dtor(struct rcu_sync *);
66
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
87#endif /* _LINUX_RCU_SYNC_H_ */