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8c366db0 | 1 | /* SPDX-License-Identifier: GPL-2.0+ */ |
621934ee PM |
2 | /* |
3 | * Sleepable Read-Copy Update mechanism for mutual exclusion | |
4 | * | |
621934ee | 5 | * Copyright (C) IBM Corporation, 2006 |
4e87b2d7 | 6 | * Copyright (C) Fujitsu, 2012 |
621934ee | 7 | * |
8c366db0 | 8 | * Author: Paul McKenney <paulmck@linux.ibm.com> |
4e87b2d7 | 9 | * Lai Jiangshan <laijs@cn.fujitsu.com> |
621934ee PM |
10 | * |
11 | * For detailed explanation of Read-Copy Update mechanism see - | |
8660b7d8 | 12 | * Documentation/RCU/ *.txt |
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13 | * |
14 | */ | |
15 | ||
eabc0694 AS |
16 | #ifndef _LINUX_SRCU_H |
17 | #define _LINUX_SRCU_H | |
18 | ||
d14aada8 | 19 | #include <linux/mutex.h> |
ff195cb6 | 20 | #include <linux/rcupdate.h> |
931ea9d1 | 21 | #include <linux/workqueue.h> |
8660b7d8 | 22 | #include <linux/rcu_segcblist.h> |
d14aada8 | 23 | |
d8be8173 | 24 | struct srcu_struct; |
c2a8ec07 | 25 | |
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26 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
27 | ||
aacb5d91 | 28 | int __init_srcu_struct(struct srcu_struct *ssp, const char *name, |
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29 | struct lock_class_key *key); |
30 | ||
aacb5d91 | 31 | #define init_srcu_struct(ssp) \ |
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32 | ({ \ |
33 | static struct lock_class_key __srcu_key; \ | |
34 | \ | |
aacb5d91 | 35 | __init_srcu_struct((ssp), #ssp, &__srcu_key); \ |
632ee200 PM |
36 | }) |
37 | ||
55c6659a | 38 | #define __SRCU_DEP_MAP_INIT(srcu_name) .dep_map = { .name = #srcu_name }, |
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39 | #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
40 | ||
aacb5d91 | 41 | int init_srcu_struct(struct srcu_struct *ssp); |
632ee200 | 42 | |
55c6659a | 43 | #define __SRCU_DEP_MAP_INIT(srcu_name) |
632ee200 PM |
44 | #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ |
45 | ||
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46 | #ifdef CONFIG_TINY_SRCU |
47 | #include <linux/srcutiny.h> | |
48 | #elif defined(CONFIG_TREE_SRCU) | |
49 | #include <linux/srcutree.h> | |
07f6e64b | 50 | #elif defined(CONFIG_SRCU) |
d8be8173 | 51 | #error "Unknown SRCU implementation specified to kernel configuration" |
07f6e64b | 52 | #else |
07f6e64b PM |
53 | /* Dummy definition for things like notifiers. Actual use gets link error. */ |
54 | struct srcu_struct { }; | |
d8be8173 | 55 | #endif |
55c6659a | 56 | |
aacb5d91 | 57 | void call_srcu(struct srcu_struct *ssp, struct rcu_head *head, |
931ea9d1 | 58 | void (*func)(struct rcu_head *head)); |
f5ad3991 | 59 | void cleanup_srcu_struct(struct srcu_struct *ssp); |
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60 | int __srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp); |
61 | void __srcu_read_unlock(struct srcu_struct *ssp, int idx) __releases(ssp); | |
62 | void synchronize_srcu(struct srcu_struct *ssp); | |
eabc0694 | 63 | |
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64 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
65 | ||
66 | /** | |
67 | * srcu_read_lock_held - might we be in SRCU read-side critical section? | |
aacb5d91 | 68 | * @ssp: The srcu_struct structure to check |
632ee200 | 69 | * |
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70 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU |
71 | * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, | |
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72 | * this assumes we are in an SRCU read-side critical section unless it can |
73 | * prove otherwise. | |
ff195cb6 | 74 | * |
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75 | * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot |
76 | * and while lockdep is disabled. | |
77 | * | |
511a0868 LJ |
78 | * Note that SRCU is based on its own statemachine and it doesn't |
79 | * relies on normal RCU, it can be called from the CPU which | |
80 | * is in the idle loop from an RCU point of view or offline. | |
632ee200 | 81 | */ |
aacb5d91 | 82 | static inline int srcu_read_lock_held(const struct srcu_struct *ssp) |
632ee200 | 83 | { |
867f236b | 84 | if (!debug_lockdep_rcu_enabled()) |
ff195cb6 | 85 | return 1; |
aacb5d91 | 86 | return lock_is_held(&ssp->dep_map); |
632ee200 PM |
87 | } |
88 | ||
89 | #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
90 | ||
aacb5d91 | 91 | static inline int srcu_read_lock_held(const struct srcu_struct *ssp) |
632ee200 PM |
92 | { |
93 | return 1; | |
94 | } | |
95 | ||
96 | #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
97 | ||
c26d34a5 | 98 | /** |
ca5ecddf PM |
99 | * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing |
100 | * @p: the pointer to fetch and protect for later dereferencing | |
aacb5d91 | 101 | * @ssp: pointer to the srcu_struct, which is used to check that we |
ca5ecddf PM |
102 | * really are in an SRCU read-side critical section. |
103 | * @c: condition to check for update-side use | |
c26d34a5 | 104 | * |
ca5ecddf PM |
105 | * If PROVE_RCU is enabled, invoking this outside of an RCU read-side |
106 | * critical section will result in an RCU-lockdep splat, unless @c evaluates | |
107 | * to 1. The @c argument will normally be a logical expression containing | |
108 | * lockdep_is_held() calls. | |
c26d34a5 | 109 | */ |
aacb5d91 PM |
110 | #define srcu_dereference_check(p, ssp, c) \ |
111 | __rcu_dereference_check((p), (c) || srcu_read_lock_held(ssp), __rcu) | |
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112 | |
113 | /** | |
114 | * srcu_dereference - fetch SRCU-protected pointer for later dereferencing | |
115 | * @p: the pointer to fetch and protect for later dereferencing | |
aacb5d91 | 116 | * @ssp: pointer to the srcu_struct, which is used to check that we |
ca5ecddf PM |
117 | * really are in an SRCU read-side critical section. |
118 | * | |
119 | * Makes rcu_dereference_check() do the dirty work. If PROVE_RCU | |
120 | * is enabled, invoking this outside of an RCU read-side critical | |
121 | * section will result in an RCU-lockdep splat. | |
122 | */ | |
aacb5d91 | 123 | #define srcu_dereference(p, ssp) srcu_dereference_check((p), (ssp), 0) |
c26d34a5 | 124 | |
0b764a6e JFG |
125 | /** |
126 | * srcu_dereference_notrace - no tracing and no lockdep calls from here | |
f3e763c3 | 127 | * @p: the pointer to fetch and protect for later dereferencing |
aacb5d91 | 128 | * @ssp: pointer to the srcu_struct, which is used to check that we |
f3e763c3 | 129 | * really are in an SRCU read-side critical section. |
0b764a6e | 130 | */ |
aacb5d91 | 131 | #define srcu_dereference_notrace(p, ssp) srcu_dereference_check((p), (ssp), 1) |
0b764a6e | 132 | |
632ee200 PM |
133 | /** |
134 | * srcu_read_lock - register a new reader for an SRCU-protected structure. | |
aacb5d91 | 135 | * @ssp: srcu_struct in which to register the new reader. |
632ee200 PM |
136 | * |
137 | * Enter an SRCU read-side critical section. Note that SRCU read-side | |
73d4da4d PM |
138 | * critical sections may be nested. However, it is illegal to |
139 | * call anything that waits on an SRCU grace period for the same | |
140 | * srcu_struct, whether directly or indirectly. Please note that | |
141 | * one way to indirectly wait on an SRCU grace period is to acquire | |
142 | * a mutex that is held elsewhere while calling synchronize_srcu() or | |
143 | * synchronize_srcu_expedited(). | |
3842a083 PM |
144 | * |
145 | * Note that srcu_read_lock() and the matching srcu_read_unlock() must | |
146 | * occur in the same context, for example, it is illegal to invoke | |
147 | * srcu_read_unlock() in an irq handler if the matching srcu_read_lock() | |
148 | * was invoked in process context. | |
632ee200 | 149 | */ |
aacb5d91 | 150 | static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp) |
632ee200 | 151 | { |
49f5903b | 152 | int retval; |
632ee200 | 153 | |
aacb5d91 PM |
154 | retval = __srcu_read_lock(ssp); |
155 | rcu_lock_acquire(&(ssp)->dep_map); | |
632ee200 PM |
156 | return retval; |
157 | } | |
158 | ||
1f45a4db PM |
159 | /* Used by tracing, cannot be traced and cannot invoke lockdep. */ |
160 | static inline notrace int | |
aacb5d91 | 161 | srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp) |
1f45a4db PM |
162 | { |
163 | int retval; | |
164 | ||
aacb5d91 | 165 | retval = __srcu_read_lock(ssp); |
1f45a4db PM |
166 | return retval; |
167 | } | |
168 | ||
632ee200 PM |
169 | /** |
170 | * srcu_read_unlock - unregister a old reader from an SRCU-protected structure. | |
aacb5d91 | 171 | * @ssp: srcu_struct in which to unregister the old reader. |
632ee200 PM |
172 | * @idx: return value from corresponding srcu_read_lock(). |
173 | * | |
174 | * Exit an SRCU read-side critical section. | |
175 | */ | |
aacb5d91 PM |
176 | static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx) |
177 | __releases(ssp) | |
632ee200 | 178 | { |
c8ca1aa7 | 179 | WARN_ON_ONCE(idx & ~0x1); |
aacb5d91 PM |
180 | rcu_lock_release(&(ssp)->dep_map); |
181 | __srcu_read_unlock(ssp, idx); | |
632ee200 PM |
182 | } |
183 | ||
1f45a4db PM |
184 | /* Used by tracing, cannot be traced and cannot call lockdep. */ |
185 | static inline notrace void | |
aacb5d91 | 186 | srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp) |
1f45a4db | 187 | { |
aacb5d91 | 188 | __srcu_read_unlock(ssp, idx); |
1f45a4db PM |
189 | } |
190 | ||
ce332f66 MT |
191 | /** |
192 | * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock | |
193 | * | |
194 | * Converts the preceding srcu_read_unlock into a two-way memory barrier. | |
195 | * | |
196 | * Call this after srcu_read_unlock, to guarantee that all memory operations | |
197 | * that occur after smp_mb__after_srcu_read_unlock will appear to happen after | |
198 | * the preceding srcu_read_unlock. | |
199 | */ | |
200 | static inline void smp_mb__after_srcu_read_unlock(void) | |
201 | { | |
202 | /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */ | |
203 | } | |
204 | ||
eabc0694 | 205 | #endif |