Fix: handle sys_futex() FUTEX_WAIT interrupted by signal
[urcu.git] / urcu / wfstack.h
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1#ifndef _URCU_WFSTACK_H
2#define _URCU_WFSTACK_H
3
4/*
edac6b69 5 * urcu/wfstack.h
cb3f3d6b 6 *
edac6b69 7 * Userspace RCU library - Stack with wait-free push, blocking traversal.
cb3f3d6b 8 *
a03a0f42 9 * Copyright 2010-2012 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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10 *
11 * This library is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU Lesser General Public
13 * License as published by the Free Software Foundation; either
14 * version 2.1 of the License, or (at your option) any later version.
15 *
16 * This library is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Lesser General Public License for more details.
20 *
21 * You should have received a copy of the GNU Lesser General Public
22 * License along with this library; if not, write to the Free Software
23 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
24 */
25
26#include <pthread.h>
27#include <assert.h>
edac6b69 28#include <stdbool.h>
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29#include <urcu/compiler.h>
30
31#ifdef __cplusplus
32extern "C" {
33#endif
34
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35/*
36 * Stack with wait-free push, blocking traversal.
37 *
38 * Stack implementing push, pop, pop_all operations, as well as iterator
39 * on the stack head returned by pop_all.
40 *
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41 * Wait-free operations: cds_wfs_push, __cds_wfs_pop_all, cds_wfs_empty,
42 * cds_wfs_first.
43 * Blocking operations: cds_wfs_pop, cds_wfs_pop_all, cds_wfs_next,
44 * iteration on stack head returned by pop_all.
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45 *
46 * Synchronization table:
47 *
48 * External synchronization techniques described in the API below is
49 * required between pairs marked with "X". No external synchronization
50 * required between pairs marked with "-".
51 *
52 * cds_wfs_push __cds_wfs_pop __cds_wfs_pop_all
53 * cds_wfs_push - - -
54 * __cds_wfs_pop - X X
55 * __cds_wfs_pop_all - X -
56 *
57 * cds_wfs_pop and cds_wfs_pop_all use an internal mutex to provide
58 * synchronization.
59 */
60
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61#define CDS_WFS_WOULDBLOCK ((void *) -1UL)
62
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63enum cds_wfs_state {
64 CDS_WFS_STATE_LAST = (1U << 0),
65};
66
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67/*
68 * struct cds_wfs_node is returned by __cds_wfs_pop, and also used as
69 * iterator on stack. It is not safe to dereference the node next
70 * pointer when returned by __cds_wfs_pop_blocking.
71 */
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72struct cds_wfs_node {
73 struct cds_wfs_node *next;
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74};
75
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76/*
77 * struct cds_wfs_head is returned by __cds_wfs_pop_all, and can be used
78 * to begin iteration on the stack. "node" needs to be the first field of
79 * cds_wfs_head, so the end-of-stack pointer value can be used for both
80 * types.
81 */
82struct cds_wfs_head {
83 struct cds_wfs_node node;
84};
85
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86struct __cds_wfs_stack {
87 struct cds_wfs_head *head;
88};
89
16aa9ee8 90struct cds_wfs_stack {
edac6b69 91 struct cds_wfs_head *head;
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92 pthread_mutex_t lock;
93};
94
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95/*
96 * The transparent union allows calling functions that work on both
97 * struct cds_wfs_stack and struct __cds_wfs_stack on any of those two
98 * types.
99 */
5135c0fd 100typedef union {
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101 struct __cds_wfs_stack *_s;
102 struct cds_wfs_stack *s;
5135c0fd 103} __attribute__((__transparent_union__)) cds_wfs_stack_ptr_t;
718eb63e 104
294d3396 105#ifdef _LGPL_SOURCE
cb3f3d6b 106
af7c2dbe 107#include <urcu/static/wfstack.h>
cb3f3d6b 108
16aa9ee8 109#define cds_wfs_node_init _cds_wfs_node_init
edac6b69 110#define cds_wfs_init _cds_wfs_init
711ff0f9 111#define __cds_wfs_init ___cds_wfs_init
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112#define cds_wfs_empty _cds_wfs_empty
113#define cds_wfs_push _cds_wfs_push
114
115/* Locking performed internally */
116#define cds_wfs_pop_blocking _cds_wfs_pop_blocking
c8975b94 117#define cds_wfs_pop_with_state_blocking _cds_wfs_pop_with_state_blocking
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118#define cds_wfs_pop_all_blocking _cds_wfs_pop_all_blocking
119
120/*
121 * For iteration on cds_wfs_head returned by __cds_wfs_pop_all or
122 * cds_wfs_pop_all_blocking.
123 */
c7ba06ba 124#define cds_wfs_first _cds_wfs_first
edac6b69 125#define cds_wfs_next_blocking _cds_wfs_next_blocking
150fc1bb 126#define cds_wfs_next_nonblocking _cds_wfs_next_nonblocking
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127
128/* Pop locking with internal mutex */
129#define cds_wfs_pop_lock _cds_wfs_pop_lock
130#define cds_wfs_pop_unlock _cds_wfs_pop_unlock
131
132/* Synchronization ensured by the caller. See synchronization table. */
133#define __cds_wfs_pop_blocking ___cds_wfs_pop_blocking
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134#define __cds_wfs_pop_with_state_blocking \
135 ___cds_wfs_pop_with_state_blocking
150fc1bb 136#define __cds_wfs_pop_nonblocking ___cds_wfs_pop_nonblocking
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137#define __cds_wfs_pop_with_state_nonblocking \
138 ___cds_wfs_pop_with_state_nonblocking
edac6b69 139#define __cds_wfs_pop_all ___cds_wfs_pop_all
cb3f3d6b 140
294d3396 141#else /* !_LGPL_SOURCE */
cb3f3d6b 142
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143/*
144 * cds_wfs_node_init: initialize wait-free stack node.
145 */
16aa9ee8 146extern void cds_wfs_node_init(struct cds_wfs_node *node);
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147
148/*
149 * cds_wfs_init: initialize wait-free stack.
150 */
16aa9ee8 151extern void cds_wfs_init(struct cds_wfs_stack *s);
edac6b69 152
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153/*
154 * __cds_wfs_init: initialize wait-free stack.
155 */
156extern void __cds_wfs_init(struct __cds_wfs_stack *s);
157
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158/*
159 * cds_wfs_empty: return whether wait-free stack is empty.
160 *
161 * No memory barrier is issued. No mutual exclusion is required.
162 */
718eb63e 163extern bool cds_wfs_empty(cds_wfs_stack_ptr_t u_stack);
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164
165/*
166 * cds_wfs_push: push a node into the stack.
167 *
168 * Issues a full memory barrier before push. No mutual exclusion is
169 * required.
170 *
171 * Returns 0 if the stack was empty prior to adding the node.
172 * Returns non-zero otherwise.
173 */
718eb63e 174extern int cds_wfs_push(cds_wfs_stack_ptr_t u_stack, struct cds_wfs_node *node);
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175
176/*
177 * cds_wfs_pop_blocking: pop a node from the stack.
178 *
179 * Calls __cds_wfs_pop_blocking with an internal pop mutex held.
180 */
16aa9ee8 181extern struct cds_wfs_node *cds_wfs_pop_blocking(struct cds_wfs_stack *s);
cb3f3d6b 182
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183/*
184 * cds_wfs_pop_with_state_blocking: pop a node from the stack, with state.
185 *
186 * Same as cds_wfs_pop_blocking, but stores whether the stack was
187 * empty into state (CDS_WFS_STATE_LAST).
188 */
189extern struct cds_wfs_node *
190 cds_wfs_pop_with_state_blocking(struct cds_wfs_stack *s, int *state);
191
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192/*
193 * cds_wfs_pop_all_blocking: pop all nodes from a stack.
194 *
195 * Calls __cds_wfs_pop_all with an internal pop mutex held.
196 */
197extern struct cds_wfs_head *cds_wfs_pop_all_blocking(struct cds_wfs_stack *s);
198
199/*
c7ba06ba 200 * cds_wfs_first: get first node of a popped stack.
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201 *
202 * Content written into the node before enqueue is guaranteed to be
203 * consistent, but no other memory ordering is ensured.
204 *
205 * Used by for-like iteration macros in urcu/wfstack.h:
206 * cds_wfs_for_each_blocking()
207 * cds_wfs_for_each_blocking_safe()
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208 *
209 * Returns NULL if popped stack is empty, top stack node otherwise.
edac6b69 210 */
c7ba06ba 211extern struct cds_wfs_node *cds_wfs_first(struct cds_wfs_head *head);
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212
213/*
214 * cds_wfs_next_blocking: get next node of a popped stack.
215 *
216 * Content written into the node before enqueue is guaranteed to be
217 * consistent, but no other memory ordering is ensured.
218 *
219 * Used by for-like iteration macros in urcu/wfstack.h:
220 * cds_wfs_for_each_blocking()
221 * cds_wfs_for_each_blocking_safe()
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222 *
223 * Returns NULL if reached end of popped stack, non-NULL next stack
224 * node otherwise.
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225 */
226extern struct cds_wfs_node *cds_wfs_next_blocking(struct cds_wfs_node *node);
227
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228/*
229 * cds_wfs_next_nonblocking: get next node of a popped stack.
230 *
231 * Same as cds_wfs_next_blocking, but returns CDS_WFS_WOULDBLOCK if it
232 * needs to block.
233 */
234extern struct cds_wfs_node *cds_wfs_next_nonblocking(struct cds_wfs_node *node);
235
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236/*
237 * cds_wfs_pop_lock: lock stack pop-protection mutex.
238 */
239extern void cds_wfs_pop_lock(struct cds_wfs_stack *s);
240
241/*
242 * cds_wfs_pop_unlock: unlock stack pop-protection mutex.
243 */
244extern void cds_wfs_pop_unlock(struct cds_wfs_stack *s);
245
246/*
247 * __cds_wfs_pop_blocking: pop a node from the stack.
248 *
249 * Returns NULL if stack is empty.
250 *
251 * __cds_wfs_pop_blocking needs to be synchronized using one of the
252 * following techniques:
253 *
254 * 1) Calling __cds_wfs_pop_blocking under rcu read lock critical
255 * section. The caller must wait for a grace period to pass before
256 * freeing the returned node or modifying the cds_wfs_node structure.
257 * 2) Using mutual exclusion (e.g. mutexes) to protect
258 * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers.
259 * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking()
260 * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme).
261 */
711ff0f9 262extern struct cds_wfs_node *__cds_wfs_pop_blocking(cds_wfs_stack_ptr_t u_stack);
edac6b69 263
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264/*
265 * __cds_wfs_pop_with_state_blocking: pop a node from the stack, with state.
266 *
267 * Same as __cds_wfs_pop_blocking, but stores whether the stack was
268 * empty into state (CDS_WFS_STATE_LAST).
269 */
270extern struct cds_wfs_node *
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271 __cds_wfs_pop_with_state_blocking(cds_wfs_stack_ptr_t u_stack,
272 int *state);
c8975b94 273
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274/*
275 * __cds_wfs_pop_nonblocking: pop a node from the stack.
276 *
277 * Same as __cds_wfs_pop_blocking, but returns CDS_WFS_WOULDBLOCK if
278 * it needs to block.
279 */
711ff0f9 280extern struct cds_wfs_node *__cds_wfs_pop_nonblocking(cds_wfs_stack_ptr_t u_stack);
af67624d 281
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282/*
283 * __cds_wfs_pop_with_state_nonblocking: pop a node from the stack, with state.
284 *
285 * Same as __cds_wfs_pop_nonblocking, but stores whether the stack was
286 * empty into state (CDS_WFS_STATE_LAST).
287 */
288extern struct cds_wfs_node *
711ff0f9 289 __cds_wfs_pop_with_state_nonblocking(cds_wfs_stack_ptr_t u_stack,
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290 int *state);
291
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292/*
293 * __cds_wfs_pop_all: pop all nodes from a stack.
294 *
295 * __cds_wfs_pop_all does not require any synchronization with other
296 * push, nor with other __cds_wfs_pop_all, but requires synchronization
297 * matching the technique used to synchronize __cds_wfs_pop_blocking:
298 *
299 * 1) If __cds_wfs_pop_blocking is called under rcu read lock critical
300 * section, both __cds_wfs_pop_blocking and cds_wfs_pop_all callers
301 * must wait for a grace period to pass before freeing the returned
302 * node or modifying the cds_wfs_node structure. However, no RCU
303 * read-side critical section is needed around __cds_wfs_pop_all.
304 * 2) Using mutual exclusion (e.g. mutexes) to protect
305 * __cds_wfs_pop_blocking and __cds_wfs_pop_all callers.
306 * 3) Ensuring that only ONE thread can call __cds_wfs_pop_blocking()
307 * and __cds_wfs_pop_all(). (multi-provider/single-consumer scheme).
308 */
711ff0f9 309extern struct cds_wfs_head *__cds_wfs_pop_all(cds_wfs_stack_ptr_t u_stack);
edac6b69 310
294d3396 311#endif /* !_LGPL_SOURCE */
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312
313#ifdef __cplusplus
314}
315#endif
316
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317/*
318 * cds_wfs_for_each_blocking: Iterate over all nodes returned by
319 * __cds_wfs_pop_all().
320 * @head: head of the queue (struct cds_wfs_head pointer).
321 * @node: iterator (struct cds_wfs_node pointer).
322 *
323 * Content written into each node before enqueue is guaranteed to be
324 * consistent, but no other memory ordering is ensured.
325 */
326#define cds_wfs_for_each_blocking(head, node) \
c7ba06ba 327 for (node = cds_wfs_first(head); \
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328 node != NULL; \
329 node = cds_wfs_next_blocking(node))
330
331/*
332 * cds_wfs_for_each_blocking_safe: Iterate over all nodes returned by
333 * __cds_wfs_pop_all(). Safe against deletion.
334 * @head: head of the queue (struct cds_wfs_head pointer).
335 * @node: iterator (struct cds_wfs_node pointer).
336 * @n: struct cds_wfs_node pointer holding the next pointer (used
337 * internally).
338 *
339 * Content written into each node before enqueue is guaranteed to be
340 * consistent, but no other memory ordering is ensured.
341 */
342#define cds_wfs_for_each_blocking_safe(head, node, n) \
c7ba06ba 343 for (node = cds_wfs_first(head), \
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344 n = (node ? cds_wfs_next_blocking(node) : NULL); \
345 node != NULL; \
346 node = n, n = (node ? cds_wfs_next_blocking(node) : NULL))
347
cb3f3d6b 348#endif /* _URCU_WFSTACK_H */
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