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. */ |
17 | struct 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 | */ |
32 | static 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 | |
39 | extern void rcu_sync_init(struct rcu_sync *); |
40 | extern void rcu_sync_enter_start(struct rcu_sync *); |
41 | extern void rcu_sync_enter(struct rcu_sync *); |
42 | extern void rcu_sync_exit(struct rcu_sync *); |
43 | extern 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_ */ |
55 | |