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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 | |
87de1cfd PM |
15 | * along with this program; if not, you can access it online at |
16 | * http://www.gnu.org/licenses/gpl-2.0.html. | |
621934ee PM |
17 | * |
18 | * Copyright (C) IBM Corporation, 2006 | |
4e87b2d7 | 19 | * Copyright (C) Fujitsu, 2012 |
621934ee PM |
20 | * |
21 | * Author: Paul McKenney <paulmck@us.ibm.com> | |
4e87b2d7 | 22 | * Lai Jiangshan <laijs@cn.fujitsu.com> |
621934ee PM |
23 | * |
24 | * For detailed explanation of Read-Copy Update mechanism see - | |
8660b7d8 | 25 | * Documentation/RCU/ *.txt |
621934ee PM |
26 | * |
27 | */ | |
28 | ||
eabc0694 AS |
29 | #ifndef _LINUX_SRCU_H |
30 | #define _LINUX_SRCU_H | |
31 | ||
d14aada8 | 32 | #include <linux/mutex.h> |
ff195cb6 | 33 | #include <linux/rcupdate.h> |
931ea9d1 | 34 | #include <linux/workqueue.h> |
8660b7d8 | 35 | #include <linux/rcu_segcblist.h> |
d14aada8 | 36 | |
d8be8173 | 37 | struct srcu_struct; |
c2a8ec07 | 38 | |
632ee200 PM |
39 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
40 | ||
41 | int __init_srcu_struct(struct srcu_struct *sp, const char *name, | |
42 | struct lock_class_key *key); | |
43 | ||
44 | #define init_srcu_struct(sp) \ | |
45 | ({ \ | |
46 | static struct lock_class_key __srcu_key; \ | |
47 | \ | |
48 | __init_srcu_struct((sp), #sp, &__srcu_key); \ | |
49 | }) | |
50 | ||
55c6659a | 51 | #define __SRCU_DEP_MAP_INIT(srcu_name) .dep_map = { .name = #srcu_name }, |
632ee200 PM |
52 | #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
53 | ||
e6a92013 | 54 | int init_srcu_struct(struct srcu_struct *sp); |
632ee200 | 55 | |
55c6659a | 56 | #define __SRCU_DEP_MAP_INIT(srcu_name) |
632ee200 PM |
57 | #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
58 | ||
d8be8173 PM |
59 | #ifdef CONFIG_TINY_SRCU |
60 | #include <linux/srcutiny.h> | |
61 | #elif defined(CONFIG_TREE_SRCU) | |
62 | #include <linux/srcutree.h> | |
dad81a20 PM |
63 | #elif defined(CONFIG_CLASSIC_SRCU) |
64 | #include <linux/srcuclassic.h> | |
d8be8173 PM |
65 | #else |
66 | #error "Unknown SRCU implementation specified to kernel configuration" | |
67 | #endif | |
55c6659a | 68 | |
931ea9d1 LJ |
69 | /** |
70 | * call_srcu() - Queue a callback for invocation after an SRCU grace period | |
71 | * @sp: srcu_struct in queue the callback | |
72 | * @head: structure to be used for queueing the SRCU callback. | |
73 | * @func: function to be invoked after the SRCU grace period | |
74 | * | |
75 | * The callback function will be invoked some time after a full SRCU | |
76 | * grace period elapses, in other words after all pre-existing SRCU | |
77 | * read-side critical sections have completed. However, the callback | |
78 | * function might well execute concurrently with other SRCU read-side | |
79 | * critical sections that started after call_srcu() was invoked. SRCU | |
80 | * read-side critical sections are delimited by srcu_read_lock() and | |
81 | * srcu_read_unlock(), and may be nested. | |
82 | * | |
83 | * The callback will be invoked from process context, but must nevertheless | |
84 | * be fast and must not block. | |
85 | */ | |
86 | void call_srcu(struct srcu_struct *sp, struct rcu_head *head, | |
87 | void (*func)(struct rcu_head *head)); | |
88 | ||
621934ee | 89 | void cleanup_srcu_struct(struct srcu_struct *sp); |
632ee200 PM |
90 | int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp); |
91 | void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp); | |
621934ee | 92 | void synchronize_srcu(struct srcu_struct *sp); |
eabc0694 | 93 | |
632ee200 PM |
94 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
95 | ||
96 | /** | |
97 | * srcu_read_lock_held - might we be in SRCU read-side critical section? | |
98 | * | |
d20200b5 PM |
99 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU |
100 | * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, | |
632ee200 PM |
101 | * this assumes we are in an SRCU read-side critical section unless it can |
102 | * prove otherwise. | |
ff195cb6 | 103 | * |
867f236b PM |
104 | * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot |
105 | * and while lockdep is disabled. | |
106 | * | |
511a0868 LJ |
107 | * Note that SRCU is based on its own statemachine and it doesn't |
108 | * relies on normal RCU, it can be called from the CPU which | |
109 | * is in the idle loop from an RCU point of view or offline. | |
632ee200 PM |
110 | */ |
111 | static inline int srcu_read_lock_held(struct srcu_struct *sp) | |
112 | { | |
867f236b | 113 | if (!debug_lockdep_rcu_enabled()) |
ff195cb6 | 114 | return 1; |
ff195cb6 | 115 | return lock_is_held(&sp->dep_map); |
632ee200 PM |
116 | } |
117 | ||
118 | #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
119 | ||
120 | static inline int srcu_read_lock_held(struct srcu_struct *sp) | |
121 | { | |
122 | return 1; | |
123 | } | |
124 | ||
125 | #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
126 | ||
c26d34a5 | 127 | /** |
ca5ecddf PM |
128 | * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing |
129 | * @p: the pointer to fetch and protect for later dereferencing | |
130 | * @sp: pointer to the srcu_struct, which is used to check that we | |
131 | * really are in an SRCU read-side critical section. | |
132 | * @c: condition to check for update-side use | |
c26d34a5 | 133 | * |
ca5ecddf PM |
134 | * If PROVE_RCU is enabled, invoking this outside of an RCU read-side |
135 | * critical section will result in an RCU-lockdep splat, unless @c evaluates | |
136 | * to 1. The @c argument will normally be a logical expression containing | |
137 | * lockdep_is_held() calls. | |
c26d34a5 | 138 | */ |
ca5ecddf | 139 | #define srcu_dereference_check(p, sp, c) \ |
b826565a | 140 | __rcu_dereference_check((p), (c) || srcu_read_lock_held(sp), __rcu) |
ca5ecddf PM |
141 | |
142 | /** | |
143 | * srcu_dereference - fetch SRCU-protected pointer for later dereferencing | |
144 | * @p: the pointer to fetch and protect for later dereferencing | |
145 | * @sp: pointer to the srcu_struct, which is used to check that we | |
146 | * really are in an SRCU read-side critical section. | |
147 | * | |
148 | * Makes rcu_dereference_check() do the dirty work. If PROVE_RCU | |
149 | * is enabled, invoking this outside of an RCU read-side critical | |
150 | * section will result in an RCU-lockdep splat. | |
151 | */ | |
152 | #define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0) | |
c26d34a5 | 153 | |
632ee200 PM |
154 | /** |
155 | * srcu_read_lock - register a new reader for an SRCU-protected structure. | |
156 | * @sp: srcu_struct in which to register the new reader. | |
157 | * | |
158 | * Enter an SRCU read-side critical section. Note that SRCU read-side | |
73d4da4d PM |
159 | * critical sections may be nested. However, it is illegal to |
160 | * call anything that waits on an SRCU grace period for the same | |
161 | * srcu_struct, whether directly or indirectly. Please note that | |
162 | * one way to indirectly wait on an SRCU grace period is to acquire | |
163 | * a mutex that is held elsewhere while calling synchronize_srcu() or | |
164 | * synchronize_srcu_expedited(). | |
3842a083 PM |
165 | * |
166 | * Note that srcu_read_lock() and the matching srcu_read_unlock() must | |
167 | * occur in the same context, for example, it is illegal to invoke | |
168 | * srcu_read_unlock() in an irq handler if the matching srcu_read_lock() | |
169 | * was invoked in process context. | |
632ee200 PM |
170 | */ |
171 | static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp) | |
172 | { | |
49f5903b | 173 | int retval; |
632ee200 | 174 | |
49f5903b | 175 | retval = __srcu_read_lock(sp); |
ff195cb6 | 176 | rcu_lock_acquire(&(sp)->dep_map); |
632ee200 PM |
177 | return retval; |
178 | } | |
179 | ||
180 | /** | |
181 | * srcu_read_unlock - unregister a old reader from an SRCU-protected structure. | |
182 | * @sp: srcu_struct in which to unregister the old reader. | |
183 | * @idx: return value from corresponding srcu_read_lock(). | |
184 | * | |
185 | * Exit an SRCU read-side critical section. | |
186 | */ | |
187 | static inline void srcu_read_unlock(struct srcu_struct *sp, int idx) | |
188 | __releases(sp) | |
189 | { | |
ff195cb6 | 190 | rcu_lock_release(&(sp)->dep_map); |
632ee200 PM |
191 | __srcu_read_unlock(sp, idx); |
192 | } | |
193 | ||
ce332f66 MT |
194 | /** |
195 | * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock | |
196 | * | |
197 | * Converts the preceding srcu_read_unlock into a two-way memory barrier. | |
198 | * | |
199 | * Call this after srcu_read_unlock, to guarantee that all memory operations | |
200 | * that occur after smp_mb__after_srcu_read_unlock will appear to happen after | |
201 | * the preceding srcu_read_unlock. | |
202 | */ | |
203 | static inline void smp_mb__after_srcu_read_unlock(void) | |
204 | { | |
205 | /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */ | |
206 | } | |
207 | ||
eabc0694 | 208 | #endif |