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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> | |
07f6e64b | 63 | #elif defined(CONFIG_SRCU) |
d8be8173 | 64 | #error "Unknown SRCU implementation specified to kernel configuration" |
07f6e64b | 65 | #else |
07f6e64b PM |
66 | /* Dummy definition for things like notifiers. Actual use gets link error. */ |
67 | struct srcu_struct { }; | |
d8be8173 | 68 | #endif |
55c6659a | 69 | |
931ea9d1 LJ |
70 | void call_srcu(struct srcu_struct *sp, struct rcu_head *head, |
71 | void (*func)(struct rcu_head *head)); | |
f7194ac3 | 72 | void _cleanup_srcu_struct(struct srcu_struct *sp, bool quiesced); |
632ee200 PM |
73 | int __srcu_read_lock(struct srcu_struct *sp) __acquires(sp); |
74 | void __srcu_read_unlock(struct srcu_struct *sp, int idx) __releases(sp); | |
621934ee | 75 | void synchronize_srcu(struct srcu_struct *sp); |
eabc0694 | 76 | |
f7194ac3 PM |
77 | /** |
78 | * cleanup_srcu_struct - deconstruct a sleep-RCU structure | |
79 | * @sp: structure to clean up. | |
80 | * | |
81 | * Must invoke this after you are finished using a given srcu_struct that | |
82 | * was initialized via init_srcu_struct(), else you leak memory. | |
83 | */ | |
84 | static inline void cleanup_srcu_struct(struct srcu_struct *sp) | |
85 | { | |
86 | _cleanup_srcu_struct(sp, false); | |
87 | } | |
88 | ||
89 | /** | |
90 | * cleanup_srcu_struct_quiesced - deconstruct a quiesced sleep-RCU structure | |
91 | * @sp: structure to clean up. | |
92 | * | |
93 | * Must invoke this after you are finished using a given srcu_struct that | |
94 | * was initialized via init_srcu_struct(), else you leak memory. Also, | |
95 | * all grace-period processing must have completed. | |
96 | * | |
97 | * "Completed" means that the last synchronize_srcu() and | |
98 | * synchronize_srcu_expedited() calls must have returned before the call | |
99 | * to cleanup_srcu_struct_quiesced(). It also means that the callback | |
100 | * from the last call_srcu() must have been invoked before the call to | |
101 | * cleanup_srcu_struct_quiesced(), but you can use srcu_barrier() to help | |
102 | * with this last. Violating these rules will get you a WARN_ON() splat | |
103 | * (with high probability, anyway), and will also cause the srcu_struct | |
104 | * to be leaked. | |
105 | */ | |
106 | static inline void cleanup_srcu_struct_quiesced(struct srcu_struct *sp) | |
107 | { | |
108 | _cleanup_srcu_struct(sp, true); | |
109 | } | |
110 | ||
632ee200 PM |
111 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
112 | ||
113 | /** | |
114 | * srcu_read_lock_held - might we be in SRCU read-side critical section? | |
27fdb35f | 115 | * @sp: The srcu_struct structure to check |
632ee200 | 116 | * |
d20200b5 PM |
117 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU |
118 | * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, | |
632ee200 PM |
119 | * this assumes we are in an SRCU read-side critical section unless it can |
120 | * prove otherwise. | |
ff195cb6 | 121 | * |
867f236b PM |
122 | * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot |
123 | * and while lockdep is disabled. | |
124 | * | |
511a0868 LJ |
125 | * Note that SRCU is based on its own statemachine and it doesn't |
126 | * relies on normal RCU, it can be called from the CPU which | |
127 | * is in the idle loop from an RCU point of view or offline. | |
632ee200 | 128 | */ |
05b93801 | 129 | static inline int srcu_read_lock_held(const struct srcu_struct *sp) |
632ee200 | 130 | { |
867f236b | 131 | if (!debug_lockdep_rcu_enabled()) |
ff195cb6 | 132 | return 1; |
ff195cb6 | 133 | return lock_is_held(&sp->dep_map); |
632ee200 PM |
134 | } |
135 | ||
136 | #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
137 | ||
05b93801 | 138 | static inline int srcu_read_lock_held(const struct srcu_struct *sp) |
632ee200 PM |
139 | { |
140 | return 1; | |
141 | } | |
142 | ||
143 | #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
144 | ||
c26d34a5 | 145 | /** |
ca5ecddf PM |
146 | * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing |
147 | * @p: the pointer to fetch and protect for later dereferencing | |
148 | * @sp: pointer to the srcu_struct, which is used to check that we | |
149 | * really are in an SRCU read-side critical section. | |
150 | * @c: condition to check for update-side use | |
c26d34a5 | 151 | * |
ca5ecddf PM |
152 | * If PROVE_RCU is enabled, invoking this outside of an RCU read-side |
153 | * critical section will result in an RCU-lockdep splat, unless @c evaluates | |
154 | * to 1. The @c argument will normally be a logical expression containing | |
155 | * lockdep_is_held() calls. | |
c26d34a5 | 156 | */ |
ca5ecddf | 157 | #define srcu_dereference_check(p, sp, c) \ |
b826565a | 158 | __rcu_dereference_check((p), (c) || srcu_read_lock_held(sp), __rcu) |
ca5ecddf PM |
159 | |
160 | /** | |
161 | * srcu_dereference - fetch SRCU-protected pointer for later dereferencing | |
162 | * @p: the pointer to fetch and protect for later dereferencing | |
163 | * @sp: pointer to the srcu_struct, which is used to check that we | |
164 | * really are in an SRCU read-side critical section. | |
165 | * | |
166 | * Makes rcu_dereference_check() do the dirty work. If PROVE_RCU | |
167 | * is enabled, invoking this outside of an RCU read-side critical | |
168 | * section will result in an RCU-lockdep splat. | |
169 | */ | |
170 | #define srcu_dereference(p, sp) srcu_dereference_check((p), (sp), 0) | |
c26d34a5 | 171 | |
0b764a6e JFG |
172 | /** |
173 | * srcu_dereference_notrace - no tracing and no lockdep calls from here | |
174 | */ | |
175 | #define srcu_dereference_notrace(p, sp) srcu_dereference_check((p), (sp), 1) | |
176 | ||
632ee200 PM |
177 | /** |
178 | * srcu_read_lock - register a new reader for an SRCU-protected structure. | |
179 | * @sp: srcu_struct in which to register the new reader. | |
180 | * | |
181 | * Enter an SRCU read-side critical section. Note that SRCU read-side | |
73d4da4d PM |
182 | * critical sections may be nested. However, it is illegal to |
183 | * call anything that waits on an SRCU grace period for the same | |
184 | * srcu_struct, whether directly or indirectly. Please note that | |
185 | * one way to indirectly wait on an SRCU grace period is to acquire | |
186 | * a mutex that is held elsewhere while calling synchronize_srcu() or | |
187 | * synchronize_srcu_expedited(). | |
3842a083 PM |
188 | * |
189 | * Note that srcu_read_lock() and the matching srcu_read_unlock() must | |
190 | * occur in the same context, for example, it is illegal to invoke | |
191 | * srcu_read_unlock() in an irq handler if the matching srcu_read_lock() | |
192 | * was invoked in process context. | |
632ee200 PM |
193 | */ |
194 | static inline int srcu_read_lock(struct srcu_struct *sp) __acquires(sp) | |
195 | { | |
49f5903b | 196 | int retval; |
632ee200 | 197 | |
49f5903b | 198 | retval = __srcu_read_lock(sp); |
ff195cb6 | 199 | rcu_lock_acquire(&(sp)->dep_map); |
632ee200 PM |
200 | return retval; |
201 | } | |
202 | ||
1f45a4db PM |
203 | /* Used by tracing, cannot be traced and cannot invoke lockdep. */ |
204 | static inline notrace int | |
205 | srcu_read_lock_notrace(struct srcu_struct *sp) __acquires(sp) | |
206 | { | |
207 | int retval; | |
208 | ||
209 | retval = __srcu_read_lock(sp); | |
210 | return retval; | |
211 | } | |
212 | ||
632ee200 PM |
213 | /** |
214 | * srcu_read_unlock - unregister a old reader from an SRCU-protected structure. | |
215 | * @sp: srcu_struct in which to unregister the old reader. | |
216 | * @idx: return value from corresponding srcu_read_lock(). | |
217 | * | |
218 | * Exit an SRCU read-side critical section. | |
219 | */ | |
220 | static inline void srcu_read_unlock(struct srcu_struct *sp, int idx) | |
221 | __releases(sp) | |
222 | { | |
ff195cb6 | 223 | rcu_lock_release(&(sp)->dep_map); |
632ee200 PM |
224 | __srcu_read_unlock(sp, idx); |
225 | } | |
226 | ||
1f45a4db PM |
227 | /* Used by tracing, cannot be traced and cannot call lockdep. */ |
228 | static inline notrace void | |
229 | srcu_read_unlock_notrace(struct srcu_struct *sp, int idx) __releases(sp) | |
230 | { | |
231 | __srcu_read_unlock(sp, idx); | |
232 | } | |
233 | ||
ce332f66 MT |
234 | /** |
235 | * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock | |
236 | * | |
237 | * Converts the preceding srcu_read_unlock into a two-way memory barrier. | |
238 | * | |
239 | * Call this after srcu_read_unlock, to guarantee that all memory operations | |
240 | * that occur after smp_mb__after_srcu_read_unlock will appear to happen after | |
241 | * the preceding srcu_read_unlock. | |
242 | */ | |
243 | static inline void smp_mb__after_srcu_read_unlock(void) | |
244 | { | |
245 | /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */ | |
246 | } | |
247 | ||
eabc0694 | 248 | #endif |