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d8be8173 PM |
1 | /* |
2 | * Sleepable Read-Copy Update mechanism for mutual exclusion, | |
3 | * tiny variant. | |
4 | * | |
5 | * This program is free software; you can redistribute it and/or modify | |
6 | * it under the terms of the GNU General Public License as published by | |
7 | * the Free Software Foundation; either version 2 of the License, or | |
8 | * (at your option) any later version. | |
9 | * | |
10 | * This program is distributed in the hope that it will be useful, | |
11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | * GNU General Public License for more details. | |
14 | * | |
15 | * You should have received a copy of the GNU General Public License | |
16 | * along with this program; if not, you can access it online at | |
17 | * http://www.gnu.org/licenses/gpl-2.0.html. | |
18 | * | |
19 | * Copyright (C) IBM Corporation, 2017 | |
20 | * | |
21 | * Author: Paul McKenney <paulmck@us.ibm.com> | |
22 | */ | |
23 | ||
24 | #ifndef _LINUX_SRCU_TINY_H | |
25 | #define _LINUX_SRCU_TINY_H | |
26 | ||
27 | #include <linux/swait.h> | |
28 | ||
29 | struct srcu_struct { | |
3ddf20c9 PM |
30 | short srcu_lock_nesting[2]; /* srcu_read_lock() nesting depth. */ |
31 | short srcu_idx; /* Current reader array element. */ | |
32 | u8 srcu_gp_running; /* GP workqueue running? */ | |
33 | u8 srcu_gp_waiting; /* GP waiting for readers? */ | |
d8be8173 PM |
34 | struct swait_queue_head srcu_wq; |
35 | /* Last srcu_read_unlock() wakes GP. */ | |
2464dd94 PM |
36 | struct rcu_head *srcu_cb_head; /* Pending callbacks: Head. */ |
37 | struct rcu_head **srcu_cb_tail; /* Pending callbacks: Tail. */ | |
d8be8173 PM |
38 | struct work_struct srcu_work; /* For driving grace periods. */ |
39 | #ifdef CONFIG_DEBUG_LOCK_ALLOC | |
40 | struct lockdep_map dep_map; | |
41 | #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
42 | }; | |
43 | ||
44 | void srcu_drive_gp(struct work_struct *wp); | |
45 | ||
46 | #define __SRCU_STRUCT_INIT(name) \ | |
47 | { \ | |
48 | .srcu_wq = __SWAIT_QUEUE_HEAD_INITIALIZER(name.srcu_wq), \ | |
2464dd94 | 49 | .srcu_cb_tail = &name.srcu_cb_head, \ |
d8be8173 PM |
50 | .srcu_work = __WORK_INITIALIZER(name.srcu_work, srcu_drive_gp), \ |
51 | __SRCU_DEP_MAP_INIT(name) \ | |
52 | } | |
53 | ||
54 | /* | |
55 | * This odd _STATIC_ arrangement is needed for API compatibility with | |
56 | * Tree SRCU, which needs some per-CPU data. | |
57 | */ | |
58 | #define DEFINE_SRCU(name) \ | |
59 | struct srcu_struct name = __SRCU_STRUCT_INIT(name) | |
60 | #define DEFINE_STATIC_SRCU(name) \ | |
61 | static struct srcu_struct name = __SRCU_STRUCT_INIT(name) | |
62 | ||
63 | void synchronize_srcu(struct srcu_struct *sp); | |
64 | ||
d4efe6c5 PM |
65 | /* |
66 | * Counts the new reader in the appropriate per-CPU element of the | |
67 | * srcu_struct. Can be invoked from irq/bh handlers, but the matching | |
68 | * __srcu_read_unlock() must be in the same handler instance. Returns an | |
69 | * index that must be passed to the matching srcu_read_unlock(). | |
70 | */ | |
71 | static inline int __srcu_read_lock(struct srcu_struct *sp) | |
72 | { | |
73 | int idx; | |
74 | ||
75 | idx = READ_ONCE(sp->srcu_idx); | |
76 | WRITE_ONCE(sp->srcu_lock_nesting[idx], sp->srcu_lock_nesting[idx] + 1); | |
77 | return idx; | |
78 | } | |
79 | ||
d8be8173 PM |
80 | static inline void synchronize_srcu_expedited(struct srcu_struct *sp) |
81 | { | |
82 | synchronize_srcu(sp); | |
83 | } | |
84 | ||
85 | static inline void srcu_barrier(struct srcu_struct *sp) | |
86 | { | |
87 | synchronize_srcu(sp); | |
88 | } | |
89 | ||
d8be8173 | 90 | #endif |