fix: warnings on non-Linux platforms
[urcu.git] / src / urcu-bp.c
CommitLineData
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1/*
2 * urcu-bp.c
3 *
4 * Userspace RCU library, "bulletproof" version.
5 *
6982d6d7 6 * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
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7 * Copyright (c) 2009 Paul E. McKenney, IBM Corporation.
8 *
9 * This library is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU Lesser General Public
11 * License as published by the Free Software Foundation; either
12 * version 2.1 of the License, or (at your option) any later version.
13 *
14 * This library is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 * Lesser General Public License for more details.
18 *
19 * You should have received a copy of the GNU Lesser General Public
20 * License along with this library; if not, write to the Free Software
21 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 *
23 * IBM's contributions to this file may be relicensed under LGPLv2 or later.
24 */
25
e37faee1 26#define URCU_NO_COMPAT_IDENTIFIERS
71c811bf 27#define _LGPL_SOURCE
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28#include <stdio.h>
29#include <pthread.h>
30#include <signal.h>
31#include <assert.h>
32#include <stdlib.h>
33#include <string.h>
34#include <errno.h>
35#include <poll.h>
36#include <unistd.h>
3745305b 37#include <stdbool.h>
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38#include <sys/mman.h>
39
375db287 40#include <urcu/config.h>
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41#include <urcu/arch.h>
42#include <urcu/wfcqueue.h>
43#include <urcu/map/urcu-bp.h>
44#include <urcu/static/urcu-bp.h>
45#include <urcu/pointer.h>
46#include <urcu/tls-compat.h>
71c811bf 47
4a6d7378 48#include "urcu-die.h"
ce28e67a 49#include "urcu-utils.h"
4a6d7378 50
4477a870 51#define URCU_API_MAP
fdee2e6d 52/* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */
71c811bf 53#undef _LGPL_SOURCE
4477a870 54#include <urcu/urcu-bp.h>
71c811bf 55#define _LGPL_SOURCE
fdee2e6d 56
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57#ifndef MAP_ANONYMOUS
58#define MAP_ANONYMOUS MAP_ANON
59#endif
60
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61#ifdef __linux__
62static
63void *mremap_wrapper(void *old_address, size_t old_size,
64 size_t new_size, int flags)
65{
66 return mremap(old_address, old_size, new_size, flags);
67}
68#else
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69
70#define MREMAP_MAYMOVE 1
71#define MREMAP_FIXED 2
72
73/*
95b94246 74 * mremap wrapper for non-Linux systems not allowing MAYMOVE.
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75 * This is not generic.
76*/
c7eaf61c 77static
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78void *mremap_wrapper(void *old_address __attribute__((unused)),
79 size_t old_size __attribute__((unused)),
80 size_t new_size __attribute__((unused)),
81 int flags)
45a4872f 82{
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83 assert(!(flags & MREMAP_MAYMOVE));
84
85 return MAP_FAILED;
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86}
87#endif
88
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89/* Sleep delay in ms */
90#define RCU_SLEEP_DELAY_MS 10
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91#define INIT_NR_THREADS 8
92#define ARENA_INIT_ALLOC \
93 sizeof(struct registry_chunk) \
4477a870 94 + INIT_NR_THREADS * sizeof(struct urcu_bp_reader)
fdee2e6d 95
b7b6a8f5
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96/*
97 * Active attempts to check for reader Q.S. before calling sleep().
98 */
99#define RCU_QS_ACTIVE_ATTEMPTS 100
100
76d6a951 101static
4477a870 102int urcu_bp_refcount;
76d6a951 103
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104/* If the headers do not support membarrier system call, fall back smp_mb. */
105#ifdef __NR_membarrier
106# define membarrier(...) syscall(__NR_membarrier, __VA_ARGS__)
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107#else
108# define membarrier(...) -ENOSYS
109#endif
110
111enum membarrier_cmd {
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112 MEMBARRIER_CMD_QUERY = 0,
113 MEMBARRIER_CMD_SHARED = (1 << 0),
114 /* reserved for MEMBARRIER_CMD_SHARED_EXPEDITED (1 << 1) */
115 /* reserved for MEMBARRIER_CMD_PRIVATE (1 << 2) */
116 MEMBARRIER_CMD_PRIVATE_EXPEDITED = (1 << 3),
117 MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED = (1 << 4),
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118};
119
c1be8fb9 120static
4477a870 121void __attribute__((constructor)) _urcu_bp_init(void);
c1be8fb9 122static
4477a870 123void __attribute__((destructor)) urcu_bp_exit(void);
fdee2e6d 124
d8d9a340 125#ifndef CONFIG_RCU_FORCE_SYS_MEMBARRIER
f541831e 126int urcu_bp_has_sys_membarrier;
d8d9a340 127#endif
f541831e 128
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129/*
130 * rcu_gp_lock ensures mutual exclusion between threads calling
131 * synchronize_rcu().
132 */
6abb4bd5 133static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER;
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134/*
135 * rcu_registry_lock ensures mutual exclusion between threads
136 * registering and unregistering themselves to/from the registry, and
137 * with threads reading that registry from synchronize_rcu(). However,
138 * this lock is not held all the way through the completion of awaiting
139 * for the grace period. It is sporadically released between iterations
140 * on the registry.
141 * rcu_registry_lock may nest inside rcu_gp_lock.
142 */
143static pthread_mutex_t rcu_registry_lock = PTHREAD_MUTEX_INITIALIZER;
fdee2e6d 144
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145static pthread_mutex_t init_lock = PTHREAD_MUTEX_INITIALIZER;
146static int initialized;
147
148static pthread_key_t urcu_bp_key;
149
4477a870 150struct urcu_bp_gp urcu_bp_gp = { .ctr = URCU_BP_GP_COUNT };
ce28e67a 151URCU_ATTR_ALIAS("urcu_bp_gp") extern struct urcu_bp_gp rcu_gp_bp;
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152
153/*
154 * Pointer to registry elements. Written to only by each individual reader. Read
155 * by both the reader and the writers.
156 */
4477a870 157DEFINE_URCU_TLS(struct urcu_bp_reader *, urcu_bp_reader);
99bfa9e9 158DEFINE_URCU_TLS_ALIAS(struct urcu_bp_reader *, urcu_bp_reader, rcu_reader_bp);
fdee2e6d 159
16aa9ee8 160static CDS_LIST_HEAD(registry);
fdee2e6d 161
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162struct registry_chunk {
163 size_t data_len; /* data length */
c1be8fb9 164 size_t used; /* amount of data used */
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165 struct cds_list_head node; /* chunk_list node */
166 char data[];
167};
168
fdee2e6d 169struct registry_arena {
95b94246 170 struct cds_list_head chunk_list;
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171};
172
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173static struct registry_arena registry_arena = {
174 .chunk_list = CDS_LIST_HEAD_INIT(registry_arena.chunk_list),
175};
fdee2e6d 176
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177/* Saved fork signal mask, protected by rcu_gp_lock */
178static sigset_t saved_fork_signal_mask;
179
6abb4bd5 180static void mutex_lock(pthread_mutex_t *mutex)
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181{
182 int ret;
183
184#ifndef DISTRUST_SIGNALS_EXTREME
6abb4bd5 185 ret = pthread_mutex_lock(mutex);
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186 if (ret)
187 urcu_die(ret);
fdee2e6d 188#else /* #ifndef DISTRUST_SIGNALS_EXTREME */
6abb4bd5 189 while ((ret = pthread_mutex_trylock(mutex)) != 0) {
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190 if (ret != EBUSY && ret != EINTR)
191 urcu_die(ret);
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192 poll(NULL,0,10);
193 }
194#endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */
195}
196
6abb4bd5 197static void mutex_unlock(pthread_mutex_t *mutex)
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198{
199 int ret;
200
6abb4bd5 201 ret = pthread_mutex_unlock(mutex);
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202 if (ret)
203 urcu_die(ret);
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204}
205
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206static void smp_mb_master(void)
207{
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208 if (caa_likely(urcu_bp_has_sys_membarrier)) {
209 if (membarrier(MEMBARRIER_CMD_PRIVATE_EXPEDITED, 0))
210 urcu_die(errno);
211 } else {
f541831e 212 cmm_smp_mb();
3745305b 213 }
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214}
215
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216/*
217 * Always called with rcu_registry lock held. Releases this lock between
218 * iterations and grabs it again. Holds the lock when it returns.
219 */
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220static void wait_for_readers(struct cds_list_head *input_readers,
221 struct cds_list_head *cur_snap_readers,
222 struct cds_list_head *qsreaders)
fdee2e6d 223{
9340c38d 224 unsigned int wait_loops = 0;
4477a870 225 struct urcu_bp_reader *index, *tmp;
fdee2e6d 226
fdee2e6d 227 /*
4477a870 228 * Wait for each thread URCU_TLS(urcu_bp_reader).ctr to either
dd61d077 229 * indicate quiescence (not nested), or observe the current
c13c2e55 230 * rcu_gp.ctr value.
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231 */
232 for (;;) {
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233 if (wait_loops < RCU_QS_ACTIVE_ATTEMPTS)
234 wait_loops++;
235
52c75091 236 cds_list_for_each_entry_safe(index, tmp, input_readers, node) {
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237 switch (urcu_bp_reader_state(&index->ctr)) {
238 case URCU_BP_READER_ACTIVE_CURRENT:
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239 if (cur_snap_readers) {
240 cds_list_move(&index->node,
241 cur_snap_readers);
242 break;
243 }
244 /* Fall-through */
4477a870 245 case URCU_BP_READER_INACTIVE:
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246 cds_list_move(&index->node, qsreaders);
247 break;
4477a870 248 case URCU_BP_READER_ACTIVE_OLD:
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249 /*
250 * Old snapshot. Leaving node in
251 * input_readers will make us busy-loop
252 * until the snapshot becomes current or
253 * the reader becomes inactive.
254 */
255 break;
256 }
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257 }
258
52c75091 259 if (cds_list_empty(input_readers)) {
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260 break;
261 } else {
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262 /* Temporarily unlock the registry lock. */
263 mutex_unlock(&rcu_registry_lock);
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264 if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS)
265 (void) poll(NULL, 0, RCU_SLEEP_DELAY_MS);
fdee2e6d 266 else
06f22bdb 267 caa_cpu_relax();
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268 /* Re-lock the registry lock before the next loop. */
269 mutex_lock(&rcu_registry_lock);
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270 }
271 }
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272}
273
4477a870 274void urcu_bp_synchronize_rcu(void)
fdee2e6d 275{
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276 CDS_LIST_HEAD(cur_snap_readers);
277 CDS_LIST_HEAD(qsreaders);
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278 sigset_t newmask, oldmask;
279 int ret;
280
6ed4b2e6 281 ret = sigfillset(&newmask);
fdee2e6d 282 assert(!ret);
6ed4b2e6 283 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
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284 assert(!ret);
285
6abb4bd5 286 mutex_lock(&rcu_gp_lock);
fdee2e6d 287
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288 mutex_lock(&rcu_registry_lock);
289
16aa9ee8 290 if (cds_list_empty(&registry))
2dfb8b5e 291 goto out;
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292
293 /* All threads should read qparity before accessing data structure
2dfb8b5e 294 * where new ptr points to. */
fdee2e6d 295 /* Write new ptr before changing the qparity */
f541831e 296 smp_mb_master();
fdee2e6d 297
fdee2e6d 298 /*
dd61d077 299 * Wait for readers to observe original parity or be quiescent.
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300 * wait_for_readers() can release and grab again rcu_registry_lock
301 * interally.
dd61d077 302 */
52c75091 303 wait_for_readers(&registry, &cur_snap_readers, &qsreaders);
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304
305 /*
306 * Adding a cmm_smp_mb() which is _not_ formally required, but makes the
307 * model easier to understand. It does not have a big performance impact
308 * anyway, given this is the write-side.
309 */
310 cmm_smp_mb();
311
312 /* Switch parity: 0 -> 1, 1 -> 0 */
4477a870 313 CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ URCU_BP_GP_CTR_PHASE);
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314
315 /*
316 * Must commit qparity update to memory before waiting for other parity
317 * quiescent state. Failure to do so could result in the writer waiting
318 * forever while new readers are always accessing data (no progress).
319 * Ensured by CMM_STORE_SHARED and CMM_LOAD_SHARED.
fdee2e6d 320 */
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321
322 /*
5481ddb3 323 * Adding a cmm_smp_mb() which is _not_ formally required, but makes the
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324 * model easier to understand. It does not have a big performance impact
325 * anyway, given this is the write-side.
326 */
5481ddb3 327 cmm_smp_mb();
fdee2e6d 328
fdee2e6d 329 /*
dd61d077 330 * Wait for readers to observe new parity or be quiescent.
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331 * wait_for_readers() can release and grab again rcu_registry_lock
332 * interally.
fdee2e6d 333 */
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334 wait_for_readers(&cur_snap_readers, NULL, &qsreaders);
335
336 /*
337 * Put quiescent reader list back into registry.
338 */
339 cds_list_splice(&qsreaders, &registry);
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340
341 /*
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342 * Finish waiting for reader threads before letting the old ptr being
343 * freed.
fdee2e6d 344 */
f541831e 345 smp_mb_master();
2dfb8b5e 346out:
731ccb96 347 mutex_unlock(&rcu_registry_lock);
6abb4bd5 348 mutex_unlock(&rcu_gp_lock);
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349 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
350 assert(!ret);
351}
ce28e67a 352URCU_ATTR_ALIAS("urcu_bp_synchronize_rcu") void synchronize_rcu_bp();
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353
354/*
355 * library wrappers to be used by non-LGPL compatible source code.
356 */
357
4477a870 358void urcu_bp_read_lock(void)
fdee2e6d 359{
4477a870 360 _urcu_bp_read_lock();
fdee2e6d 361}
ce28e67a 362URCU_ATTR_ALIAS("urcu_bp_read_lock") void rcu_read_lock_bp();
fdee2e6d 363
4477a870 364void urcu_bp_read_unlock(void)
fdee2e6d 365{
4477a870 366 _urcu_bp_read_unlock();
fdee2e6d 367}
ce28e67a 368URCU_ATTR_ALIAS("urcu_bp_read_unlock") void rcu_read_unlock_bp();
fdee2e6d 369
4477a870 370int urcu_bp_read_ongoing(void)
882f3357 371{
4477a870 372 return _urcu_bp_read_ongoing();
882f3357 373}
ce28e67a 374URCU_ATTR_ALIAS("urcu_bp_read_ongoing") int rcu_read_ongoing_bp();
882f3357 375
fdee2e6d 376/*
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377 * Only grow for now. If empty, allocate a ARENA_INIT_ALLOC sized chunk.
378 * Else, try expanding the last chunk. If this fails, allocate a new
379 * chunk twice as big as the last chunk.
380 * Memory used by chunks _never_ moves. A chunk could theoretically be
381 * freed when all "used" slots are released, but we don't do it at this
382 * point.
fdee2e6d 383 */
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384static
385void expand_arena(struct registry_arena *arena)
fdee2e6d 386{
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387 struct registry_chunk *new_chunk, *last_chunk;
388 size_t old_chunk_len, new_chunk_len;
389
390 /* No chunk. */
391 if (cds_list_empty(&arena->chunk_list)) {
392 assert(ARENA_INIT_ALLOC >=
393 sizeof(struct registry_chunk)
394 + sizeof(struct rcu_reader));
395 new_chunk_len = ARENA_INIT_ALLOC;
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396 new_chunk = (struct registry_chunk *) mmap(NULL,
397 new_chunk_len,
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398 PROT_READ | PROT_WRITE,
399 MAP_ANONYMOUS | MAP_PRIVATE,
400 -1, 0);
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401 if (new_chunk == MAP_FAILED)
402 abort();
d3ac5bb7 403 memset(new_chunk, 0, new_chunk_len);
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404 new_chunk->data_len =
405 new_chunk_len - sizeof(struct registry_chunk);
406 cds_list_add_tail(&new_chunk->node, &arena->chunk_list);
407 return; /* We're done. */
408 }
9d8612b7 409
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410 /* Try expanding last chunk. */
411 last_chunk = cds_list_entry(arena->chunk_list.prev,
412 struct registry_chunk, node);
413 old_chunk_len =
414 last_chunk->data_len + sizeof(struct registry_chunk);
415 new_chunk_len = old_chunk_len << 1;
416
417 /* Don't allow memory mapping to move, just expand. */
418 new_chunk = mremap_wrapper(last_chunk, old_chunk_len,
419 new_chunk_len, 0);
420 if (new_chunk != MAP_FAILED) {
421 /* Should not have moved. */
422 assert(new_chunk == last_chunk);
d3ac5bb7 423 memset((char *) last_chunk + old_chunk_len, 0,
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424 new_chunk_len - old_chunk_len);
425 last_chunk->data_len =
426 new_chunk_len - sizeof(struct registry_chunk);
427 return; /* We're done. */
428 }
0617bf4c 429
95b94246 430 /* Remap did not succeed, we need to add a new chunk. */
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431 new_chunk = (struct registry_chunk *) mmap(NULL,
432 new_chunk_len,
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433 PROT_READ | PROT_WRITE,
434 MAP_ANONYMOUS | MAP_PRIVATE,
435 -1, 0);
436 if (new_chunk == MAP_FAILED)
437 abort();
d3ac5bb7 438 memset(new_chunk, 0, new_chunk_len);
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439 new_chunk->data_len =
440 new_chunk_len - sizeof(struct registry_chunk);
441 cds_list_add_tail(&new_chunk->node, &arena->chunk_list);
442}
fdee2e6d 443
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444static
445struct rcu_reader *arena_alloc(struct registry_arena *arena)
446{
447 struct registry_chunk *chunk;
448 struct rcu_reader *rcu_reader_reg;
449 int expand_done = 0; /* Only allow to expand once per alloc */
450 size_t len = sizeof(struct rcu_reader);
451
452retry:
453 cds_list_for_each_entry(chunk, &arena->chunk_list, node) {
454 if (chunk->data_len - chunk->used < len)
455 continue;
456 /* Find spot */
457 for (rcu_reader_reg = (struct rcu_reader *) &chunk->data[0];
458 rcu_reader_reg < (struct rcu_reader *) &chunk->data[chunk->data_len];
459 rcu_reader_reg++) {
460 if (!rcu_reader_reg->alloc) {
461 rcu_reader_reg->alloc = 1;
462 chunk->used += len;
463 return rcu_reader_reg;
464 }
465 }
466 }
467
468 if (!expand_done) {
469 expand_arena(arena);
470 expand_done = 1;
471 goto retry;
472 }
473
474 return NULL;
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475}
476
477/* Called with signals off and mutex locked */
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478static
479void add_thread(void)
fdee2e6d 480{
02be5561 481 struct rcu_reader *rcu_reader_reg;
c1be8fb9 482 int ret;
fdee2e6d 483
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484 rcu_reader_reg = arena_alloc(&registry_arena);
485 if (!rcu_reader_reg)
486 abort();
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487 ret = pthread_setspecific(urcu_bp_key, rcu_reader_reg);
488 if (ret)
489 abort();
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490
491 /* Add to registry */
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492 rcu_reader_reg->tid = pthread_self();
493 assert(rcu_reader_reg->ctr == 0);
16aa9ee8 494 cds_list_add(&rcu_reader_reg->node, &registry);
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495 /*
496 * Reader threads are pointing to the reader registry. This is
497 * why its memory should never be relocated.
498 */
4477a870 499 URCU_TLS(urcu_bp_reader) = rcu_reader_reg;
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500}
501
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502/* Called with mutex locked */
503static
504void cleanup_thread(struct registry_chunk *chunk,
505 struct rcu_reader *rcu_reader_reg)
506{
507 rcu_reader_reg->ctr = 0;
508 cds_list_del(&rcu_reader_reg->node);
509 rcu_reader_reg->tid = 0;
510 rcu_reader_reg->alloc = 0;
511 chunk->used -= sizeof(struct rcu_reader);
512}
513
514static
515struct registry_chunk *find_chunk(struct rcu_reader *rcu_reader_reg)
fdee2e6d 516{
95b94246 517 struct registry_chunk *chunk;
fdee2e6d 518
95b94246 519 cds_list_for_each_entry(chunk, &registry_arena.chunk_list, node) {
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520 if (rcu_reader_reg < (struct rcu_reader *) &chunk->data[0])
521 continue;
522 if (rcu_reader_reg >= (struct rcu_reader *) &chunk->data[chunk->data_len])
523 continue;
524 return chunk;
525 }
526 return NULL;
527}
95b94246 528
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529/* Called with signals off and mutex locked */
530static
76d6a951 531void remove_thread(struct rcu_reader *rcu_reader_reg)
c1be8fb9 532{
c1be8fb9 533 cleanup_thread(find_chunk(rcu_reader_reg), rcu_reader_reg);
4477a870 534 URCU_TLS(urcu_bp_reader) = NULL;
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535}
536
537/* Disable signals, take mutex, add to registry */
4477a870 538void urcu_bp_register(void)
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539{
540 sigset_t newmask, oldmask;
541 int ret;
542
6ed4b2e6 543 ret = sigfillset(&newmask);
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544 if (ret)
545 abort();
6ed4b2e6 546 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
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547 if (ret)
548 abort();
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549
550 /*
551 * Check if a signal concurrently registered our thread since
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552 * the check in rcu_read_lock().
553 */
4477a870 554 if (URCU_TLS(urcu_bp_reader))
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555 goto end;
556
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557 /*
558 * Take care of early registration before urcu_bp constructor.
559 */
4477a870 560 _urcu_bp_init();
c1be8fb9 561
731ccb96 562 mutex_lock(&rcu_registry_lock);
fdee2e6d 563 add_thread();
731ccb96 564 mutex_unlock(&rcu_registry_lock);
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565end:
566 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
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567 if (ret)
568 abort();
569}
ce28e67a 570URCU_ATTR_ALIAS("urcu_bp_register") void rcu_bp_register();
c1be8fb9 571
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572void urcu_bp_register_thread(void)
573{
574 if (caa_unlikely(!URCU_TLS(urcu_bp_reader)))
575 urcu_bp_register(); /* If not yet registered. */
576}
577
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578/* Disable signals, take mutex, remove from registry */
579static
4477a870 580void urcu_bp_unregister(struct rcu_reader *rcu_reader_reg)
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581{
582 sigset_t newmask, oldmask;
583 int ret;
584
585 ret = sigfillset(&newmask);
586 if (ret)
587 abort();
588 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
589 if (ret)
590 abort();
591
731ccb96 592 mutex_lock(&rcu_registry_lock);
76d6a951 593 remove_thread(rcu_reader_reg);
731ccb96 594 mutex_unlock(&rcu_registry_lock);
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595 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
596 if (ret)
597 abort();
4477a870 598 urcu_bp_exit();
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599}
600
601/*
602 * Remove thread from the registry when it exits, and flag it as
603 * destroyed so garbage collection can take care of it.
604 */
605static
606void urcu_bp_thread_exit_notifier(void *rcu_key)
607{
4477a870 608 urcu_bp_unregister(rcu_key);
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609}
610
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611#ifdef CONFIG_RCU_FORCE_SYS_MEMBARRIER
612static
4477a870 613void urcu_bp_sys_membarrier_status(bool available)
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614{
615 if (!available)
616 abort();
617}
618#else
619static
4477a870 620void urcu_bp_sys_membarrier_status(bool available)
d8d9a340 621{
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622 if (!available)
623 return;
624 urcu_bp_has_sys_membarrier = 1;
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625}
626#endif
627
3745305b 628static
4477a870 629void urcu_bp_sys_membarrier_init(void)
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630{
631 bool available = false;
632 int mask;
633
634 mask = membarrier(MEMBARRIER_CMD_QUERY, 0);
635 if (mask >= 0) {
636 if (mask & MEMBARRIER_CMD_PRIVATE_EXPEDITED) {
637 if (membarrier(MEMBARRIER_CMD_REGISTER_PRIVATE_EXPEDITED, 0))
638 urcu_die(errno);
639 available = true;
640 }
641 }
4477a870 642 urcu_bp_sys_membarrier_status(available);
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643}
644
c1be8fb9 645static
4477a870 646void _urcu_bp_init(void)
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647{
648 mutex_lock(&init_lock);
4477a870 649 if (!urcu_bp_refcount++) {
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650 int ret;
651
652 ret = pthread_key_create(&urcu_bp_key,
653 urcu_bp_thread_exit_notifier);
654 if (ret)
655 abort();
4477a870 656 urcu_bp_sys_membarrier_init();
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657 initialized = 1;
658 }
659 mutex_unlock(&init_lock);
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660}
661
c1be8fb9 662static
4477a870 663void urcu_bp_exit(void)
fdee2e6d 664{
76d6a951 665 mutex_lock(&init_lock);
4477a870 666 if (!--urcu_bp_refcount) {
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667 struct registry_chunk *chunk, *tmp;
668 int ret;
95b94246 669
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670 cds_list_for_each_entry_safe(chunk, tmp,
671 &registry_arena.chunk_list, node) {
5592d049 672 munmap((void *) chunk, chunk->data_len
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673 + sizeof(struct registry_chunk));
674 }
7937ae1c 675 CDS_INIT_LIST_HEAD(&registry_arena.chunk_list);
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676 ret = pthread_key_delete(urcu_bp_key);
677 if (ret)
678 abort();
95b94246 679 }
76d6a951 680 mutex_unlock(&init_lock);
fdee2e6d 681}
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682
683/*
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684 * Holding the rcu_gp_lock and rcu_registry_lock across fork will make
685 * sure we fork() don't race with a concurrent thread executing with
686 * any of those locks held. This ensures that the registry and data
687 * protected by rcu_gp_lock are in a coherent state in the child.
4cf1675f 688 */
4477a870 689void urcu_bp_before_fork(void)
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690{
691 sigset_t newmask, oldmask;
692 int ret;
693
6ed4b2e6 694 ret = sigfillset(&newmask);
4cf1675f 695 assert(!ret);
6ed4b2e6 696 ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask);
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697 assert(!ret);
698 mutex_lock(&rcu_gp_lock);
731ccb96 699 mutex_lock(&rcu_registry_lock);
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700 saved_fork_signal_mask = oldmask;
701}
ce28e67a 702URCU_ATTR_ALIAS("urcu_bp_before_fork") void rcu_bp_before_fork();
4cf1675f 703
4477a870 704void urcu_bp_after_fork_parent(void)
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705{
706 sigset_t oldmask;
707 int ret;
708
709 oldmask = saved_fork_signal_mask;
731ccb96 710 mutex_unlock(&rcu_registry_lock);
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711 mutex_unlock(&rcu_gp_lock);
712 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
713 assert(!ret);
714}
ce28e67a 715URCU_ATTR_ALIAS("urcu_bp_after_fork_parent")
4477a870 716void rcu_bp_after_fork_parent(void);
4cf1675f 717
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718/*
719 * Prune all entries from registry except our own thread. Fits the Linux
731ccb96 720 * fork behavior. Called with rcu_gp_lock and rcu_registry_lock held.
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721 */
722static
723void urcu_bp_prune_registry(void)
724{
725 struct registry_chunk *chunk;
4477a870 726 struct urcu_bp_reader *rcu_reader_reg;
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727
728 cds_list_for_each_entry(chunk, &registry_arena.chunk_list, node) {
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729 for (rcu_reader_reg = (struct urcu_bp_reader *) &chunk->data[0];
730 rcu_reader_reg < (struct urcu_bp_reader *) &chunk->data[chunk->data_len];
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731 rcu_reader_reg++) {
732 if (!rcu_reader_reg->alloc)
733 continue;
734 if (rcu_reader_reg->tid == pthread_self())
735 continue;
736 cleanup_thread(chunk, rcu_reader_reg);
737 }
738 }
739}
740
4477a870 741void urcu_bp_after_fork_child(void)
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742{
743 sigset_t oldmask;
744 int ret;
745
c1be8fb9 746 urcu_bp_prune_registry();
4cf1675f 747 oldmask = saved_fork_signal_mask;
731ccb96 748 mutex_unlock(&rcu_registry_lock);
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749 mutex_unlock(&rcu_gp_lock);
750 ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
751 assert(!ret);
752}
ce28e67a 753URCU_ATTR_ALIAS("urcu_bp_after_fork_child")
4477a870 754void rcu_bp_after_fork_child(void);
5e77fc1f 755
4477a870 756void *urcu_bp_dereference_sym(void *p)
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757{
758 return _rcu_dereference(p);
759}
ce28e67a 760URCU_ATTR_ALIAS("urcu_bp_dereference_sym")
4477a870 761void *rcu_dereference_sym_bp();
9b7981bb 762
4477a870 763void *urcu_bp_set_pointer_sym(void **p, void *v)
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764{
765 cmm_wmb();
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766 uatomic_set(p, v);
767 return v;
5efd3cd2 768}
ce28e67a 769URCU_ATTR_ALIAS("urcu_bp_set_pointer_sym")
4477a870 770void *rcu_set_pointer_sym_bp();
5efd3cd2 771
4477a870 772void *urcu_bp_xchg_pointer_sym(void **p, void *v)
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773{
774 cmm_wmb();
775 return uatomic_xchg(p, v);
776}
ce28e67a 777URCU_ATTR_ALIAS("urcu_bp_xchg_pointer_sym")
4477a870 778void *rcu_xchg_pointer_sym_bp();
5efd3cd2 779
4477a870 780void *urcu_bp_cmpxchg_pointer_sym(void **p, void *old, void *_new)
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781{
782 cmm_wmb();
783 return uatomic_cmpxchg(p, old, _new);
784}
ce28e67a 785URCU_ATTR_ALIAS("urcu_bp_cmpxchg_pointer_sym")
4477a870 786void *rcu_cmpxchg_pointer_sym_bp();
5efd3cd2 787
5e6b23a6 788DEFINE_RCU_FLAVOR(rcu_flavor);
4477a870 789DEFINE_RCU_FLAVOR_ALIAS(rcu_flavor, alias_rcu_flavor);
541d828d 790
5e77fc1f 791#include "urcu-call-rcu-impl.h"
0376e7b2 792#include "urcu-defer-impl.h"
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