]>
Commit | Line | Data |
---|---|---|
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 |
621934ee PM |
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 | |
632ee200 PM |
26 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
27 | ||
aacb5d91 | 28 | int __init_srcu_struct(struct srcu_struct *ssp, const char *name, |
632ee200 PM |
29 | struct lock_class_key *key); |
30 | ||
aacb5d91 | 31 | #define init_srcu_struct(ssp) \ |
632ee200 PM |
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 }, |
632ee200 PM |
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 | ||
d8be8173 PM |
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); |
aacb5d91 PM |
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); | |
8b5bd67c PM |
63 | unsigned long get_state_synchronize_srcu(struct srcu_struct *ssp); |
64 | unsigned long start_poll_synchronize_srcu(struct srcu_struct *ssp); | |
65 | bool poll_state_synchronize_srcu(struct srcu_struct *ssp, unsigned long cookie); | |
eabc0694 | 66 | |
8e9c01c7 FW |
67 | #ifdef CONFIG_SRCU |
68 | void srcu_init(void); | |
69 | #else /* #ifdef CONFIG_SRCU */ | |
70 | static inline void srcu_init(void) { } | |
71 | #endif /* #else #ifdef CONFIG_SRCU */ | |
72 | ||
632ee200 PM |
73 | #ifdef CONFIG_DEBUG_LOCK_ALLOC |
74 | ||
75 | /** | |
76 | * srcu_read_lock_held - might we be in SRCU read-side critical section? | |
aacb5d91 | 77 | * @ssp: The srcu_struct structure to check |
632ee200 | 78 | * |
d20200b5 PM |
79 | * If CONFIG_DEBUG_LOCK_ALLOC is selected, returns nonzero iff in an SRCU |
80 | * read-side critical section. In absence of CONFIG_DEBUG_LOCK_ALLOC, | |
632ee200 PM |
81 | * this assumes we are in an SRCU read-side critical section unless it can |
82 | * prove otherwise. | |
ff195cb6 | 83 | * |
867f236b PM |
84 | * Checks debug_lockdep_rcu_enabled() to prevent false positives during boot |
85 | * and while lockdep is disabled. | |
86 | * | |
511a0868 LJ |
87 | * Note that SRCU is based on its own statemachine and it doesn't |
88 | * relies on normal RCU, it can be called from the CPU which | |
89 | * is in the idle loop from an RCU point of view or offline. | |
632ee200 | 90 | */ |
aacb5d91 | 91 | static inline int srcu_read_lock_held(const struct srcu_struct *ssp) |
632ee200 | 92 | { |
867f236b | 93 | if (!debug_lockdep_rcu_enabled()) |
ff195cb6 | 94 | return 1; |
aacb5d91 | 95 | return lock_is_held(&ssp->dep_map); |
632ee200 PM |
96 | } |
97 | ||
98 | #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
99 | ||
aacb5d91 | 100 | static inline int srcu_read_lock_held(const struct srcu_struct *ssp) |
632ee200 PM |
101 | { |
102 | return 1; | |
103 | } | |
104 | ||
105 | #endif /* #else #ifdef CONFIG_DEBUG_LOCK_ALLOC */ | |
106 | ||
c26d34a5 | 107 | /** |
ca5ecddf PM |
108 | * srcu_dereference_check - fetch SRCU-protected pointer for later dereferencing |
109 | * @p: the pointer to fetch and protect for later dereferencing | |
aacb5d91 | 110 | * @ssp: pointer to the srcu_struct, which is used to check that we |
ca5ecddf PM |
111 | * really are in an SRCU read-side critical section. |
112 | * @c: condition to check for update-side use | |
c26d34a5 | 113 | * |
ca5ecddf PM |
114 | * If PROVE_RCU is enabled, invoking this outside of an RCU read-side |
115 | * critical section will result in an RCU-lockdep splat, unless @c evaluates | |
116 | * to 1. The @c argument will normally be a logical expression containing | |
117 | * lockdep_is_held() calls. | |
c26d34a5 | 118 | */ |
aacb5d91 PM |
119 | #define srcu_dereference_check(p, ssp, c) \ |
120 | __rcu_dereference_check((p), (c) || srcu_read_lock_held(ssp), __rcu) | |
ca5ecddf PM |
121 | |
122 | /** | |
123 | * srcu_dereference - fetch SRCU-protected pointer for later dereferencing | |
124 | * @p: the pointer to fetch and protect for later dereferencing | |
aacb5d91 | 125 | * @ssp: pointer to the srcu_struct, which is used to check that we |
ca5ecddf PM |
126 | * really are in an SRCU read-side critical section. |
127 | * | |
128 | * Makes rcu_dereference_check() do the dirty work. If PROVE_RCU | |
129 | * is enabled, invoking this outside of an RCU read-side critical | |
130 | * section will result in an RCU-lockdep splat. | |
131 | */ | |
aacb5d91 | 132 | #define srcu_dereference(p, ssp) srcu_dereference_check((p), (ssp), 0) |
c26d34a5 | 133 | |
0b764a6e JFG |
134 | /** |
135 | * srcu_dereference_notrace - no tracing and no lockdep calls from here | |
f3e763c3 | 136 | * @p: the pointer to fetch and protect for later dereferencing |
aacb5d91 | 137 | * @ssp: pointer to the srcu_struct, which is used to check that we |
f3e763c3 | 138 | * really are in an SRCU read-side critical section. |
0b764a6e | 139 | */ |
aacb5d91 | 140 | #define srcu_dereference_notrace(p, ssp) srcu_dereference_check((p), (ssp), 1) |
0b764a6e | 141 | |
632ee200 PM |
142 | /** |
143 | * srcu_read_lock - register a new reader for an SRCU-protected structure. | |
aacb5d91 | 144 | * @ssp: srcu_struct in which to register the new reader. |
632ee200 PM |
145 | * |
146 | * Enter an SRCU read-side critical section. Note that SRCU read-side | |
73d4da4d PM |
147 | * critical sections may be nested. However, it is illegal to |
148 | * call anything that waits on an SRCU grace period for the same | |
149 | * srcu_struct, whether directly or indirectly. Please note that | |
150 | * one way to indirectly wait on an SRCU grace period is to acquire | |
151 | * a mutex that is held elsewhere while calling synchronize_srcu() or | |
152 | * synchronize_srcu_expedited(). | |
3842a083 PM |
153 | * |
154 | * Note that srcu_read_lock() and the matching srcu_read_unlock() must | |
155 | * occur in the same context, for example, it is illegal to invoke | |
156 | * srcu_read_unlock() in an irq handler if the matching srcu_read_lock() | |
157 | * was invoked in process context. | |
632ee200 | 158 | */ |
aacb5d91 | 159 | static inline int srcu_read_lock(struct srcu_struct *ssp) __acquires(ssp) |
632ee200 | 160 | { |
49f5903b | 161 | int retval; |
632ee200 | 162 | |
aacb5d91 PM |
163 | retval = __srcu_read_lock(ssp); |
164 | rcu_lock_acquire(&(ssp)->dep_map); | |
632ee200 PM |
165 | return retval; |
166 | } | |
167 | ||
1f45a4db PM |
168 | /* Used by tracing, cannot be traced and cannot invoke lockdep. */ |
169 | static inline notrace int | |
aacb5d91 | 170 | srcu_read_lock_notrace(struct srcu_struct *ssp) __acquires(ssp) |
1f45a4db PM |
171 | { |
172 | int retval; | |
173 | ||
aacb5d91 | 174 | retval = __srcu_read_lock(ssp); |
1f45a4db PM |
175 | return retval; |
176 | } | |
177 | ||
632ee200 PM |
178 | /** |
179 | * srcu_read_unlock - unregister a old reader from an SRCU-protected structure. | |
aacb5d91 | 180 | * @ssp: srcu_struct in which to unregister the old reader. |
632ee200 PM |
181 | * @idx: return value from corresponding srcu_read_lock(). |
182 | * | |
183 | * Exit an SRCU read-side critical section. | |
184 | */ | |
aacb5d91 PM |
185 | static inline void srcu_read_unlock(struct srcu_struct *ssp, int idx) |
186 | __releases(ssp) | |
632ee200 | 187 | { |
c8ca1aa7 | 188 | WARN_ON_ONCE(idx & ~0x1); |
aacb5d91 PM |
189 | rcu_lock_release(&(ssp)->dep_map); |
190 | __srcu_read_unlock(ssp, idx); | |
632ee200 PM |
191 | } |
192 | ||
1f45a4db PM |
193 | /* Used by tracing, cannot be traced and cannot call lockdep. */ |
194 | static inline notrace void | |
aacb5d91 | 195 | srcu_read_unlock_notrace(struct srcu_struct *ssp, int idx) __releases(ssp) |
1f45a4db | 196 | { |
aacb5d91 | 197 | __srcu_read_unlock(ssp, idx); |
1f45a4db PM |
198 | } |
199 | ||
ce332f66 MT |
200 | /** |
201 | * smp_mb__after_srcu_read_unlock - ensure full ordering after srcu_read_unlock | |
202 | * | |
203 | * Converts the preceding srcu_read_unlock into a two-way memory barrier. | |
204 | * | |
205 | * Call this after srcu_read_unlock, to guarantee that all memory operations | |
206 | * that occur after smp_mb__after_srcu_read_unlock will appear to happen after | |
207 | * the preceding srcu_read_unlock. | |
208 | */ | |
209 | static inline void smp_mb__after_srcu_read_unlock(void) | |
210 | { | |
211 | /* __srcu_read_unlock has smp_mb() internally so nothing to do here. */ | |
212 | } | |
213 | ||
eabc0694 | 214 | #endif |