Commit | Line | Data |
---|---|---|
621934ee PM |
1 | /* |
2 | * Sleepable Read-Copy Update mechanism for mutual exclusion | |
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, write to the Free Software | |
16 | * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. | |
17 | * | |
18 | * Copyright (C) IBM Corporation, 2006 | |
19 | * | |
20 | * Author: Paul McKenney <paulmck@us.ibm.com> | |
21 | * | |
22 | * For detailed explanation of Read-Copy Update mechanism see - | |
23 | * Documentation/RCU/ *.txt | |
24 | * | |
25 | */ | |
26 | ||
eabc0694 AS |
27 | #ifndef _LINUX_SRCU_H |
28 | #define _LINUX_SRCU_H | |
29 | ||
d14aada8 PM |
30 | #include <linux/mutex.h> |
31 | ||
621934ee PM |
32 | struct srcu_struct_array { |
33 | int c[2]; | |
34 | }; | |
35 | ||
36 | struct srcu_struct { | |
37 | int completed; | |
43cf38eb | 38 | struct srcu_struct_array __percpu *per_cpu_ref; |
621934ee | 39 | struct mutex mutex; |
632ee200 PM |
40 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
41 | struct lockdep_map dep_map; | |
42 | #endif /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
621934ee PM |
43 | }; |
44 | ||
45 | #ifndef CONFIG_PREEMPT | |
46 | #define srcu_barrier() barrier() | |
47 | #else /* #ifndef CONFIG_PREEMPT */ | |
48 | #define srcu_barrier() | |
49 | #endif /* #else #ifndef CONFIG_PREEMPT */ | |
50 | ||
632ee200 PM |
51 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
52 | ||
53 | int __init_srcu_struct(struct srcu_struct *sp, const char *name, | |
54 | struct lock_class_key *key); | |
55 | ||
56 | #define init_srcu_struct(sp) \ | |
57 | ({ \ | |
58 | static struct lock_class_key __srcu_key; \ | |
59 | \ | |
60 | __init_srcu_struct((sp), #sp, &__srcu_key); \ | |
61 | }) | |
62 | ||
63 | # define srcu_read_acquire(sp) \ | |
64 | lock_acquire(&(sp)->dep_map, 0, 0, 2, 1, NULL, _THIS_IP_) | |
65 | # define srcu_read_release(sp) \ | |
66 | lock_release(&(sp)->dep_map, 1, _THIS_IP_) | |
67 | ||
68 | #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
69 | ||
e6a92013 | 70 | int init_srcu_struct(struct srcu_struct *sp); |
632ee200 PM |
71 | |
72 | # define srcu_read_acquire(sp) do { } while (0) | |
73 | # define srcu_read_release(sp) do { } while (0) | |
74 | ||
75 | #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
76 | ||
621934ee | 77 | void cleanup_srcu_struct(struct srcu_struct *sp); |
632ee200 PM |
78 | int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp); |
79 | void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp); | |
621934ee | 80 | void synchronize_srcu(struct srcu_struct *sp); |
0cd397d3 | 81 | void synchronize_srcu_expedited(struct srcu_struct *sp); |
621934ee | 82 | long srcu_batches_completed(struct srcu_struct *sp); |
eabc0694 | 83 | |
632ee200 PM |
84 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
85 | ||
86 | /** | |
87 | * srcu_read_lock_held - might we be in SRCU read-side critical section? | |
88 | * | |
d20200b5 PM |
89 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU |
90 | * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, | |
632ee200 PM |
91 | * this assumes we are in an SRCU read-side critical section unless it can |
92 | * prove otherwise. | |
93 | */ | |
94 | static inline int srcu_read_lock_held(struct srcu_struct *sp) | |
95 | { | |
96 | if (debug_locks) | |
97 | return lock_is_held(&sp->dep_map); | |
98 | return 1; | |
99 | } | |
100 | ||
101 | #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
102 | ||
103 | static inline int srcu_read_lock_held(struct srcu_struct *sp) | |
104 | { | |
105 | return 1; | |
106 | } | |
107 | ||
108 | #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
109 | ||
c26d34a5 | 110 | /** |
ca5ecddf PM |
111 | * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing |
112 | * @p: the pointer to fetch and protect for later dereferencing | |
113 | * @sp: pointer to the srcu_struct, which is used to check that we | |
114 | * really are in an SRCU read-side critical section. | |
115 | * @c: condition to check for update-side use | |
c26d34a5 | 116 | * |
ca5ecddf PM |
117 | * If PROVE_RCU is enabled, invoking this outside of an RCU read-side |
118 | * critical section will result in an RCU-lockdep splat, unless @c evaluates | |
119 | * to 1. The @c argument will normally be a logical expression containing | |
120 | * lockdep_is_held() calls. | |
c26d34a5 | 121 | */ |
ca5ecddf PM |
122 | #define srcu_dereference_check(p, sp, c) \ |
123 | __rcu_dereference_check((p), srcu_read_lock_held(sp) || (c), __rcu) | |
124 | ||
125 | /** | |
126 | * srcu_dereference - fetch SRCU-protected pointer for later dereferencing | |
127 | * @p: the pointer to fetch and protect for later dereferencing | |
128 | * @sp: pointer to the srcu_struct, which is used to check that we | |
129 | * really are in an SRCU read-side critical section. | |
130 | * | |
131 | * Makes rcu_dereference_check() do the dirty work. If PROVE_RCU | |
132 | * is enabled, invoking this outside of an RCU read-side critical | |
133 | * section will result in an RCU-lockdep splat. | |
134 | */ | |
135 | #define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0) | |
c26d34a5 | 136 | |
632ee200 PM |
137 | /** |
138 | * srcu_read_lock - register a new reader for an SRCU-protected structure. | |
139 | * @sp: srcu_struct in which to register the new reader. | |
140 | * | |
141 | * Enter an SRCU read-side critical section. Note that SRCU read-side | |
73d4da4d PM |
142 | * critical sections may be nested. However, it is illegal to |
143 | * call anything that waits on an SRCU grace period for the same | |
144 | * srcu_struct, whether directly or indirectly. Please note that | |
145 | * one way to indirectly wait on an SRCU grace period is to acquire | |
146 | * a mutex that is held elsewhere while calling synchronize_srcu() or | |
147 | * synchronize_srcu_expedited(). | |
632ee200 PM |
148 | */ |
149 | static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp) | |
150 | { | |
151 | int retval = __srcu_read_lock(sp); | |
152 | ||
153 | srcu_read_acquire(sp); | |
154 | return retval; | |
155 | } | |
156 | ||
157 | /** | |
158 | * srcu_read_unlock - unregister a old reader from an SRCU-protected structure. | |
159 | * @sp: srcu_struct in which to unregister the old reader. | |
160 | * @idx: return value from corresponding srcu_read_lock(). | |
161 | * | |
162 | * Exit an SRCU read-side critical section. | |
163 | */ | |
164 | static inline void srcu_read_unlock(struct srcu_struct *sp, int idx) | |
165 | __releases(sp) | |
166 | { | |
167 | srcu_read_release(sp); | |
168 | __srcu_read_unlock(sp, idx); | |
169 | } | |
170 | ||
eabc0694 | 171 | #endif |