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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 | }; |
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 |
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 | { | |
95bf33b5 ON |
34 | RCU_LOCKDEP_WARN(!rcu_read_lock_held() && |
35 | !rcu_read_lock_bh_held() && | |
36 | !rcu_read_lock_sched_held(), | |
37 | "suspicious rcu_sync_is_idle() usage"); | |
89da3b94 | 38 | return !READ_ONCE(rsp->gp_state); /* GP_IDLE */ |
cc44ca84 ON |
39 | } |
40 | ||
95bf33b5 | 41 | extern void rcu_sync_init(struct rcu_sync *); |
3942a9bd | 42 | extern void rcu_sync_enter_start(struct rcu_sync *); |
cc44ca84 ON |
43 | extern void rcu_sync_enter(struct rcu_sync *); |
44 | extern void rcu_sync_exit(struct rcu_sync *); | |
07899a6e | 45 | extern void rcu_sync_dtor(struct rcu_sync *); |
cc44ca84 | 46 | |
95bf33b5 | 47 | #define __RCU_SYNC_INITIALIZER(name) { \ |
82e8c565 ON |
48 | .gp_state = 0, \ |
49 | .gp_count = 0, \ | |
50 | .gp_wait = __WAIT_QUEUE_HEAD_INITIALIZER(name.gp_wait), \ | |
82e8c565 ON |
51 | } |
52 | ||
95bf33b5 ON |
53 | #define DEFINE_RCU_SYNC(name) \ |
54 | struct rcu_sync name = __RCU_SYNC_INITIALIZER(name) | |
82e8c565 | 55 | |
cc44ca84 | 56 | #endif /* _LINUX_RCU_SYNC_H_ */ |