Commit | Line | Data |
---|---|---|
fdee2e6d MD |
1 | /* |
2 | * urcu-bp.c | |
3 | * | |
4 | * Userspace RCU library, "bulletproof" version. | |
5 | * | |
6982d6d7 | 6 | * Copyright (c) 2009 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
fdee2e6d MD |
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 | ||
71c811bf | 26 | #define _LGPL_SOURCE |
fdee2e6d MD |
27 | #include <stdio.h> |
28 | #include <pthread.h> | |
29 | #include <signal.h> | |
30 | #include <assert.h> | |
31 | #include <stdlib.h> | |
32 | #include <string.h> | |
33 | #include <errno.h> | |
34 | #include <poll.h> | |
35 | #include <unistd.h> | |
36 | #include <sys/mman.h> | |
37 | ||
999991c6 | 38 | #include "urcu/arch.h" |
d73fb81f | 39 | #include "urcu/wfcqueue.h" |
57760d44 | 40 | #include "urcu/map/urcu-bp.h" |
af7c2dbe | 41 | #include "urcu/static/urcu-bp.h" |
618b2595 | 42 | #include "urcu-pointer.h" |
bd252a04 | 43 | #include "urcu/tls-compat.h" |
71c811bf | 44 | |
4a6d7378 MD |
45 | #include "urcu-die.h" |
46 | ||
fdee2e6d | 47 | /* Do not #define _LGPL_SOURCE to ensure we can emit the wrapper symbols */ |
71c811bf | 48 | #undef _LGPL_SOURCE |
fdee2e6d | 49 | #include "urcu-bp.h" |
71c811bf | 50 | #define _LGPL_SOURCE |
fdee2e6d | 51 | |
4c1ae2ea MD |
52 | #ifndef MAP_ANONYMOUS |
53 | #define MAP_ANONYMOUS MAP_ANON | |
54 | #endif | |
55 | ||
c7eaf61c MD |
56 | #ifdef __linux__ |
57 | static | |
58 | void *mremap_wrapper(void *old_address, size_t old_size, | |
59 | size_t new_size, int flags) | |
60 | { | |
61 | return mremap(old_address, old_size, new_size, flags); | |
62 | } | |
63 | #else | |
45a4872f MD |
64 | |
65 | #define MREMAP_MAYMOVE 1 | |
66 | #define MREMAP_FIXED 2 | |
67 | ||
68 | /* | |
95b94246 | 69 | * mremap wrapper for non-Linux systems not allowing MAYMOVE. |
45a4872f MD |
70 | * This is not generic. |
71 | */ | |
c7eaf61c MD |
72 | static |
73 | void *mremap_wrapper(void *old_address, size_t old_size, | |
74 | size_t new_size, int flags) | |
45a4872f | 75 | { |
95b94246 MD |
76 | assert(!(flags & MREMAP_MAYMOVE)); |
77 | ||
78 | return MAP_FAILED; | |
45a4872f MD |
79 | } |
80 | #endif | |
81 | ||
9340c38d MD |
82 | /* Sleep delay in ms */ |
83 | #define RCU_SLEEP_DELAY_MS 10 | |
95b94246 MD |
84 | #define INIT_NR_THREADS 8 |
85 | #define ARENA_INIT_ALLOC \ | |
86 | sizeof(struct registry_chunk) \ | |
87 | + INIT_NR_THREADS * sizeof(struct rcu_reader) | |
fdee2e6d | 88 | |
b7b6a8f5 PB |
89 | /* |
90 | * Active attempts to check for reader Q.S. before calling sleep(). | |
91 | */ | |
92 | #define RCU_QS_ACTIVE_ATTEMPTS 100 | |
93 | ||
76d6a951 MD |
94 | static |
95 | int rcu_bp_refcount; | |
96 | ||
999991c6 MD |
97 | /* If the headers do not support membarrier system call, fall back smp_mb. */ |
98 | #ifdef __NR_membarrier | |
99 | # define membarrier(...) syscall(__NR_membarrier, __VA_ARGS__) | |
f541831e MD |
100 | #else |
101 | # define membarrier(...) -ENOSYS | |
102 | #endif | |
103 | ||
104 | enum membarrier_cmd { | |
105 | MEMBARRIER_CMD_QUERY = 0, | |
106 | MEMBARRIER_CMD_SHARED = (1 << 0), | |
107 | }; | |
108 | ||
c1be8fb9 MD |
109 | static |
110 | void __attribute__((constructor)) rcu_bp_init(void); | |
111 | static | |
02be5561 | 112 | void __attribute__((destructor)) rcu_bp_exit(void); |
fdee2e6d | 113 | |
f541831e MD |
114 | int urcu_bp_has_sys_membarrier; |
115 | ||
731ccb96 MD |
116 | /* |
117 | * rcu_gp_lock ensures mutual exclusion between threads calling | |
118 | * synchronize_rcu(). | |
119 | */ | |
6abb4bd5 | 120 | static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER; |
731ccb96 MD |
121 | /* |
122 | * rcu_registry_lock ensures mutual exclusion between threads | |
123 | * registering and unregistering themselves to/from the registry, and | |
124 | * with threads reading that registry from synchronize_rcu(). However, | |
125 | * this lock is not held all the way through the completion of awaiting | |
126 | * for the grace period. It is sporadically released between iterations | |
127 | * on the registry. | |
128 | * rcu_registry_lock may nest inside rcu_gp_lock. | |
129 | */ | |
130 | static pthread_mutex_t rcu_registry_lock = PTHREAD_MUTEX_INITIALIZER; | |
fdee2e6d | 131 | |
c1be8fb9 MD |
132 | static pthread_mutex_t init_lock = PTHREAD_MUTEX_INITIALIZER; |
133 | static int initialized; | |
134 | ||
135 | static pthread_key_t urcu_bp_key; | |
136 | ||
c13c2e55 | 137 | struct rcu_gp rcu_gp = { .ctr = RCU_GP_COUNT }; |
fdee2e6d MD |
138 | |
139 | /* | |
140 | * Pointer to registry elements. Written to only by each individual reader. Read | |
141 | * by both the reader and the writers. | |
142 | */ | |
bd252a04 | 143 | DEFINE_URCU_TLS(struct rcu_reader *, rcu_reader); |
fdee2e6d | 144 | |
16aa9ee8 | 145 | static CDS_LIST_HEAD(registry); |
fdee2e6d | 146 | |
95b94246 MD |
147 | struct registry_chunk { |
148 | size_t data_len; /* data length */ | |
c1be8fb9 | 149 | size_t used; /* amount of data used */ |
95b94246 MD |
150 | struct cds_list_head node; /* chunk_list node */ |
151 | char data[]; | |
152 | }; | |
153 | ||
fdee2e6d | 154 | struct registry_arena { |
95b94246 | 155 | struct cds_list_head chunk_list; |
fdee2e6d MD |
156 | }; |
157 | ||
95b94246 MD |
158 | static struct registry_arena registry_arena = { |
159 | .chunk_list = CDS_LIST_HEAD_INIT(registry_arena.chunk_list), | |
160 | }; | |
fdee2e6d | 161 | |
4cf1675f MD |
162 | /* Saved fork signal mask, protected by rcu_gp_lock */ |
163 | static sigset_t saved_fork_signal_mask; | |
164 | ||
6abb4bd5 | 165 | static void mutex_lock(pthread_mutex_t *mutex) |
fdee2e6d MD |
166 | { |
167 | int ret; | |
168 | ||
169 | #ifndef DISTRUST_SIGNALS_EXTREME | |
6abb4bd5 | 170 | ret = pthread_mutex_lock(mutex); |
4a6d7378 MD |
171 | if (ret) |
172 | urcu_die(ret); | |
fdee2e6d | 173 | #else /* #ifndef DISTRUST_SIGNALS_EXTREME */ |
6abb4bd5 | 174 | while ((ret = pthread_mutex_trylock(mutex)) != 0) { |
4a6d7378 MD |
175 | if (ret != EBUSY && ret != EINTR) |
176 | urcu_die(ret); | |
fdee2e6d MD |
177 | poll(NULL,0,10); |
178 | } | |
179 | #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */ | |
180 | } | |
181 | ||
6abb4bd5 | 182 | static void mutex_unlock(pthread_mutex_t *mutex) |
fdee2e6d MD |
183 | { |
184 | int ret; | |
185 | ||
6abb4bd5 | 186 | ret = pthread_mutex_unlock(mutex); |
4a6d7378 MD |
187 | if (ret) |
188 | urcu_die(ret); | |
fdee2e6d MD |
189 | } |
190 | ||
f541831e MD |
191 | static void smp_mb_master(void) |
192 | { | |
193 | if (caa_likely(urcu_bp_has_sys_membarrier)) | |
194 | (void) membarrier(MEMBARRIER_CMD_SHARED, 0); | |
195 | else | |
196 | cmm_smp_mb(); | |
197 | } | |
198 | ||
731ccb96 MD |
199 | /* |
200 | * Always called with rcu_registry lock held. Releases this lock between | |
201 | * iterations and grabs it again. Holds the lock when it returns. | |
202 | */ | |
52c75091 MD |
203 | static void wait_for_readers(struct cds_list_head *input_readers, |
204 | struct cds_list_head *cur_snap_readers, | |
205 | struct cds_list_head *qsreaders) | |
fdee2e6d | 206 | { |
9340c38d | 207 | unsigned int wait_loops = 0; |
02be5561 | 208 | struct rcu_reader *index, *tmp; |
fdee2e6d | 209 | |
fdee2e6d | 210 | /* |
dd61d077 MD |
211 | * Wait for each thread URCU_TLS(rcu_reader).ctr to either |
212 | * indicate quiescence (not nested), or observe the current | |
c13c2e55 | 213 | * rcu_gp.ctr value. |
fdee2e6d MD |
214 | */ |
215 | for (;;) { | |
9340c38d MD |
216 | if (wait_loops < RCU_QS_ACTIVE_ATTEMPTS) |
217 | wait_loops++; | |
218 | ||
52c75091 MD |
219 | cds_list_for_each_entry_safe(index, tmp, input_readers, node) { |
220 | switch (rcu_reader_state(&index->ctr)) { | |
221 | case RCU_READER_ACTIVE_CURRENT: | |
222 | if (cur_snap_readers) { | |
223 | cds_list_move(&index->node, | |
224 | cur_snap_readers); | |
225 | break; | |
226 | } | |
227 | /* Fall-through */ | |
228 | case RCU_READER_INACTIVE: | |
229 | cds_list_move(&index->node, qsreaders); | |
230 | break; | |
231 | case RCU_READER_ACTIVE_OLD: | |
232 | /* | |
233 | * Old snapshot. Leaving node in | |
234 | * input_readers will make us busy-loop | |
235 | * until the snapshot becomes current or | |
236 | * the reader becomes inactive. | |
237 | */ | |
238 | break; | |
239 | } | |
fdee2e6d MD |
240 | } |
241 | ||
52c75091 | 242 | if (cds_list_empty(input_readers)) { |
fdee2e6d MD |
243 | break; |
244 | } else { | |
731ccb96 MD |
245 | /* Temporarily unlock the registry lock. */ |
246 | mutex_unlock(&rcu_registry_lock); | |
9340c38d MD |
247 | if (wait_loops >= RCU_QS_ACTIVE_ATTEMPTS) |
248 | (void) poll(NULL, 0, RCU_SLEEP_DELAY_MS); | |
fdee2e6d | 249 | else |
06f22bdb | 250 | caa_cpu_relax(); |
731ccb96 MD |
251 | /* Re-lock the registry lock before the next loop. */ |
252 | mutex_lock(&rcu_registry_lock); | |
fdee2e6d MD |
253 | } |
254 | } | |
fdee2e6d MD |
255 | } |
256 | ||
257 | void synchronize_rcu(void) | |
258 | { | |
52c75091 MD |
259 | CDS_LIST_HEAD(cur_snap_readers); |
260 | CDS_LIST_HEAD(qsreaders); | |
fdee2e6d MD |
261 | sigset_t newmask, oldmask; |
262 | int ret; | |
263 | ||
6ed4b2e6 | 264 | ret = sigfillset(&newmask); |
fdee2e6d | 265 | assert(!ret); |
6ed4b2e6 | 266 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); |
fdee2e6d MD |
267 | assert(!ret); |
268 | ||
6abb4bd5 | 269 | mutex_lock(&rcu_gp_lock); |
fdee2e6d | 270 | |
731ccb96 MD |
271 | mutex_lock(&rcu_registry_lock); |
272 | ||
16aa9ee8 | 273 | if (cds_list_empty(®istry)) |
2dfb8b5e | 274 | goto out; |
fdee2e6d MD |
275 | |
276 | /* All threads should read qparity before accessing data structure | |
2dfb8b5e | 277 | * where new ptr points to. */ |
fdee2e6d | 278 | /* Write new ptr before changing the qparity */ |
f541831e | 279 | smp_mb_master(); |
fdee2e6d | 280 | |
fdee2e6d | 281 | /* |
dd61d077 | 282 | * Wait for readers to observe original parity or be quiescent. |
731ccb96 MD |
283 | * wait_for_readers() can release and grab again rcu_registry_lock |
284 | * interally. | |
dd61d077 | 285 | */ |
52c75091 | 286 | wait_for_readers(®istry, &cur_snap_readers, &qsreaders); |
dd61d077 MD |
287 | |
288 | /* | |
289 | * Adding a cmm_smp_mb() which is _not_ formally required, but makes the | |
290 | * model easier to understand. It does not have a big performance impact | |
291 | * anyway, given this is the write-side. | |
292 | */ | |
293 | cmm_smp_mb(); | |
294 | ||
295 | /* Switch parity: 0 -> 1, 1 -> 0 */ | |
c13c2e55 | 296 | CMM_STORE_SHARED(rcu_gp.ctr, rcu_gp.ctr ^ RCU_GP_CTR_PHASE); |
dd61d077 MD |
297 | |
298 | /* | |
299 | * Must commit qparity update to memory before waiting for other parity | |
300 | * quiescent state. Failure to do so could result in the writer waiting | |
301 | * forever while new readers are always accessing data (no progress). | |
302 | * Ensured by CMM_STORE_SHARED and CMM_LOAD_SHARED. | |
fdee2e6d | 303 | */ |
fdee2e6d MD |
304 | |
305 | /* | |
5481ddb3 | 306 | * Adding a cmm_smp_mb() which is _not_ formally required, but makes the |
fdee2e6d MD |
307 | * model easier to understand. It does not have a big performance impact |
308 | * anyway, given this is the write-side. | |
309 | */ | |
5481ddb3 | 310 | cmm_smp_mb(); |
fdee2e6d | 311 | |
fdee2e6d | 312 | /* |
dd61d077 | 313 | * Wait for readers to observe new parity or be quiescent. |
731ccb96 MD |
314 | * wait_for_readers() can release and grab again rcu_registry_lock |
315 | * interally. | |
fdee2e6d | 316 | */ |
52c75091 MD |
317 | wait_for_readers(&cur_snap_readers, NULL, &qsreaders); |
318 | ||
319 | /* | |
320 | * Put quiescent reader list back into registry. | |
321 | */ | |
322 | cds_list_splice(&qsreaders, ®istry); | |
fdee2e6d MD |
323 | |
324 | /* | |
2dfb8b5e MD |
325 | * Finish waiting for reader threads before letting the old ptr being |
326 | * freed. | |
fdee2e6d | 327 | */ |
f541831e | 328 | smp_mb_master(); |
2dfb8b5e | 329 | out: |
731ccb96 | 330 | mutex_unlock(&rcu_registry_lock); |
6abb4bd5 | 331 | mutex_unlock(&rcu_gp_lock); |
fdee2e6d MD |
332 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); |
333 | assert(!ret); | |
334 | } | |
335 | ||
336 | /* | |
337 | * library wrappers to be used by non-LGPL compatible source code. | |
338 | */ | |
339 | ||
340 | void rcu_read_lock(void) | |
341 | { | |
342 | _rcu_read_lock(); | |
343 | } | |
344 | ||
345 | void rcu_read_unlock(void) | |
346 | { | |
347 | _rcu_read_unlock(); | |
348 | } | |
349 | ||
882f3357 MD |
350 | int rcu_read_ongoing(void) |
351 | { | |
352 | return _rcu_read_ongoing(); | |
353 | } | |
354 | ||
fdee2e6d | 355 | /* |
95b94246 MD |
356 | * Only grow for now. If empty, allocate a ARENA_INIT_ALLOC sized chunk. |
357 | * Else, try expanding the last chunk. If this fails, allocate a new | |
358 | * chunk twice as big as the last chunk. | |
359 | * Memory used by chunks _never_ moves. A chunk could theoretically be | |
360 | * freed when all "used" slots are released, but we don't do it at this | |
361 | * point. | |
fdee2e6d | 362 | */ |
95b94246 MD |
363 | static |
364 | void expand_arena(struct registry_arena *arena) | |
fdee2e6d | 365 | { |
95b94246 MD |
366 | struct registry_chunk *new_chunk, *last_chunk; |
367 | size_t old_chunk_len, new_chunk_len; | |
368 | ||
369 | /* No chunk. */ | |
370 | if (cds_list_empty(&arena->chunk_list)) { | |
371 | assert(ARENA_INIT_ALLOC >= | |
372 | sizeof(struct registry_chunk) | |
373 | + sizeof(struct rcu_reader)); | |
374 | new_chunk_len = ARENA_INIT_ALLOC; | |
375 | new_chunk = mmap(NULL, new_chunk_len, | |
9d8612b7 MD |
376 | PROT_READ | PROT_WRITE, |
377 | MAP_ANONYMOUS | MAP_PRIVATE, | |
378 | -1, 0); | |
95b94246 MD |
379 | if (new_chunk == MAP_FAILED) |
380 | abort(); | |
d3ac5bb7 | 381 | memset(new_chunk, 0, new_chunk_len); |
95b94246 MD |
382 | new_chunk->data_len = |
383 | new_chunk_len - sizeof(struct registry_chunk); | |
384 | cds_list_add_tail(&new_chunk->node, &arena->chunk_list); | |
385 | return; /* We're done. */ | |
386 | } | |
9d8612b7 | 387 | |
95b94246 MD |
388 | /* Try expanding last chunk. */ |
389 | last_chunk = cds_list_entry(arena->chunk_list.prev, | |
390 | struct registry_chunk, node); | |
391 | old_chunk_len = | |
392 | last_chunk->data_len + sizeof(struct registry_chunk); | |
393 | new_chunk_len = old_chunk_len << 1; | |
394 | ||
395 | /* Don't allow memory mapping to move, just expand. */ | |
396 | new_chunk = mremap_wrapper(last_chunk, old_chunk_len, | |
397 | new_chunk_len, 0); | |
398 | if (new_chunk != MAP_FAILED) { | |
399 | /* Should not have moved. */ | |
400 | assert(new_chunk == last_chunk); | |
d3ac5bb7 | 401 | memset((char *) last_chunk + old_chunk_len, 0, |
95b94246 MD |
402 | new_chunk_len - old_chunk_len); |
403 | last_chunk->data_len = | |
404 | new_chunk_len - sizeof(struct registry_chunk); | |
405 | return; /* We're done. */ | |
406 | } | |
0617bf4c | 407 | |
95b94246 MD |
408 | /* Remap did not succeed, we need to add a new chunk. */ |
409 | new_chunk = mmap(NULL, new_chunk_len, | |
410 | PROT_READ | PROT_WRITE, | |
411 | MAP_ANONYMOUS | MAP_PRIVATE, | |
412 | -1, 0); | |
413 | if (new_chunk == MAP_FAILED) | |
414 | abort(); | |
d3ac5bb7 | 415 | memset(new_chunk, 0, new_chunk_len); |
95b94246 MD |
416 | new_chunk->data_len = |
417 | new_chunk_len - sizeof(struct registry_chunk); | |
418 | cds_list_add_tail(&new_chunk->node, &arena->chunk_list); | |
419 | } | |
fdee2e6d | 420 | |
95b94246 MD |
421 | static |
422 | struct rcu_reader *arena_alloc(struct registry_arena *arena) | |
423 | { | |
424 | struct registry_chunk *chunk; | |
425 | struct rcu_reader *rcu_reader_reg; | |
426 | int expand_done = 0; /* Only allow to expand once per alloc */ | |
427 | size_t len = sizeof(struct rcu_reader); | |
428 | ||
429 | retry: | |
430 | cds_list_for_each_entry(chunk, &arena->chunk_list, node) { | |
431 | if (chunk->data_len - chunk->used < len) | |
432 | continue; | |
433 | /* Find spot */ | |
434 | for (rcu_reader_reg = (struct rcu_reader *) &chunk->data[0]; | |
435 | rcu_reader_reg < (struct rcu_reader *) &chunk->data[chunk->data_len]; | |
436 | rcu_reader_reg++) { | |
437 | if (!rcu_reader_reg->alloc) { | |
438 | rcu_reader_reg->alloc = 1; | |
439 | chunk->used += len; | |
440 | return rcu_reader_reg; | |
441 | } | |
442 | } | |
443 | } | |
444 | ||
445 | if (!expand_done) { | |
446 | expand_arena(arena); | |
447 | expand_done = 1; | |
448 | goto retry; | |
449 | } | |
450 | ||
451 | return NULL; | |
fdee2e6d MD |
452 | } |
453 | ||
454 | /* Called with signals off and mutex locked */ | |
95b94246 MD |
455 | static |
456 | void add_thread(void) | |
fdee2e6d | 457 | { |
02be5561 | 458 | struct rcu_reader *rcu_reader_reg; |
c1be8fb9 | 459 | int ret; |
fdee2e6d | 460 | |
95b94246 MD |
461 | rcu_reader_reg = arena_alloc(®istry_arena); |
462 | if (!rcu_reader_reg) | |
463 | abort(); | |
c1be8fb9 MD |
464 | ret = pthread_setspecific(urcu_bp_key, rcu_reader_reg); |
465 | if (ret) | |
466 | abort(); | |
fdee2e6d MD |
467 | |
468 | /* Add to registry */ | |
02be5561 MD |
469 | rcu_reader_reg->tid = pthread_self(); |
470 | assert(rcu_reader_reg->ctr == 0); | |
16aa9ee8 | 471 | cds_list_add(&rcu_reader_reg->node, ®istry); |
95b94246 MD |
472 | /* |
473 | * Reader threads are pointing to the reader registry. This is | |
474 | * why its memory should never be relocated. | |
475 | */ | |
bd252a04 | 476 | URCU_TLS(rcu_reader) = rcu_reader_reg; |
fdee2e6d MD |
477 | } |
478 | ||
c1be8fb9 MD |
479 | /* Called with mutex locked */ |
480 | static | |
481 | void cleanup_thread(struct registry_chunk *chunk, | |
482 | struct rcu_reader *rcu_reader_reg) | |
483 | { | |
484 | rcu_reader_reg->ctr = 0; | |
485 | cds_list_del(&rcu_reader_reg->node); | |
486 | rcu_reader_reg->tid = 0; | |
487 | rcu_reader_reg->alloc = 0; | |
488 | chunk->used -= sizeof(struct rcu_reader); | |
489 | } | |
490 | ||
491 | static | |
492 | struct registry_chunk *find_chunk(struct rcu_reader *rcu_reader_reg) | |
fdee2e6d | 493 | { |
95b94246 | 494 | struct registry_chunk *chunk; |
fdee2e6d | 495 | |
95b94246 | 496 | cds_list_for_each_entry(chunk, ®istry_arena.chunk_list, node) { |
c1be8fb9 MD |
497 | if (rcu_reader_reg < (struct rcu_reader *) &chunk->data[0]) |
498 | continue; | |
499 | if (rcu_reader_reg >= (struct rcu_reader *) &chunk->data[chunk->data_len]) | |
500 | continue; | |
501 | return chunk; | |
502 | } | |
503 | return NULL; | |
504 | } | |
95b94246 | 505 | |
c1be8fb9 MD |
506 | /* Called with signals off and mutex locked */ |
507 | static | |
76d6a951 | 508 | void remove_thread(struct rcu_reader *rcu_reader_reg) |
c1be8fb9 | 509 | { |
c1be8fb9 MD |
510 | cleanup_thread(find_chunk(rcu_reader_reg), rcu_reader_reg); |
511 | URCU_TLS(rcu_reader) = NULL; | |
fdee2e6d MD |
512 | } |
513 | ||
514 | /* Disable signals, take mutex, add to registry */ | |
515 | void rcu_bp_register(void) | |
516 | { | |
517 | sigset_t newmask, oldmask; | |
518 | int ret; | |
519 | ||
6ed4b2e6 | 520 | ret = sigfillset(&newmask); |
c1be8fb9 MD |
521 | if (ret) |
522 | abort(); | |
6ed4b2e6 | 523 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); |
c1be8fb9 MD |
524 | if (ret) |
525 | abort(); | |
fdee2e6d MD |
526 | |
527 | /* | |
528 | * Check if a signal concurrently registered our thread since | |
c1be8fb9 MD |
529 | * the check in rcu_read_lock(). |
530 | */ | |
bd252a04 | 531 | if (URCU_TLS(rcu_reader)) |
fdee2e6d MD |
532 | goto end; |
533 | ||
c1be8fb9 MD |
534 | /* |
535 | * Take care of early registration before urcu_bp constructor. | |
536 | */ | |
537 | rcu_bp_init(); | |
538 | ||
731ccb96 | 539 | mutex_lock(&rcu_registry_lock); |
fdee2e6d | 540 | add_thread(); |
731ccb96 | 541 | mutex_unlock(&rcu_registry_lock); |
fdee2e6d MD |
542 | end: |
543 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
c1be8fb9 MD |
544 | if (ret) |
545 | abort(); | |
546 | } | |
547 | ||
548 | /* Disable signals, take mutex, remove from registry */ | |
549 | static | |
76d6a951 | 550 | void rcu_bp_unregister(struct rcu_reader *rcu_reader_reg) |
c1be8fb9 MD |
551 | { |
552 | sigset_t newmask, oldmask; | |
553 | int ret; | |
554 | ||
555 | ret = sigfillset(&newmask); | |
556 | if (ret) | |
557 | abort(); | |
558 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); | |
559 | if (ret) | |
560 | abort(); | |
561 | ||
731ccb96 | 562 | mutex_lock(&rcu_registry_lock); |
76d6a951 | 563 | remove_thread(rcu_reader_reg); |
731ccb96 | 564 | mutex_unlock(&rcu_registry_lock); |
c1be8fb9 MD |
565 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); |
566 | if (ret) | |
567 | abort(); | |
76d6a951 | 568 | rcu_bp_exit(); |
c1be8fb9 MD |
569 | } |
570 | ||
571 | /* | |
572 | * Remove thread from the registry when it exits, and flag it as | |
573 | * destroyed so garbage collection can take care of it. | |
574 | */ | |
575 | static | |
576 | void urcu_bp_thread_exit_notifier(void *rcu_key) | |
577 | { | |
76d6a951 | 578 | rcu_bp_unregister(rcu_key); |
c1be8fb9 MD |
579 | } |
580 | ||
581 | static | |
582 | void rcu_bp_init(void) | |
583 | { | |
584 | mutex_lock(&init_lock); | |
76d6a951 | 585 | if (!rcu_bp_refcount++) { |
c1be8fb9 MD |
586 | int ret; |
587 | ||
588 | ret = pthread_key_create(&urcu_bp_key, | |
589 | urcu_bp_thread_exit_notifier); | |
590 | if (ret) | |
591 | abort(); | |
f541831e MD |
592 | ret = membarrier(MEMBARRIER_CMD_QUERY, 0); |
593 | if (ret >= 0 && (ret & MEMBARRIER_CMD_SHARED)) { | |
594 | urcu_bp_has_sys_membarrier = 1; | |
595 | } | |
c1be8fb9 MD |
596 | initialized = 1; |
597 | } | |
598 | mutex_unlock(&init_lock); | |
fdee2e6d MD |
599 | } |
600 | ||
c1be8fb9 | 601 | static |
9380711a | 602 | void rcu_bp_exit(void) |
fdee2e6d | 603 | { |
76d6a951 MD |
604 | mutex_lock(&init_lock); |
605 | if (!--rcu_bp_refcount) { | |
606 | struct registry_chunk *chunk, *tmp; | |
607 | int ret; | |
95b94246 | 608 | |
76d6a951 MD |
609 | cds_list_for_each_entry_safe(chunk, tmp, |
610 | ®istry_arena.chunk_list, node) { | |
611 | munmap(chunk, chunk->data_len | |
612 | + sizeof(struct registry_chunk)); | |
613 | } | |
7937ae1c | 614 | CDS_INIT_LIST_HEAD(®istry_arena.chunk_list); |
76d6a951 MD |
615 | ret = pthread_key_delete(urcu_bp_key); |
616 | if (ret) | |
617 | abort(); | |
95b94246 | 618 | } |
76d6a951 | 619 | mutex_unlock(&init_lock); |
fdee2e6d | 620 | } |
4cf1675f MD |
621 | |
622 | /* | |
731ccb96 MD |
623 | * Holding the rcu_gp_lock and rcu_registry_lock across fork will make |
624 | * sure we fork() don't race with a concurrent thread executing with | |
625 | * any of those locks held. This ensures that the registry and data | |
626 | * protected by rcu_gp_lock are in a coherent state in the child. | |
4cf1675f MD |
627 | */ |
628 | void rcu_bp_before_fork(void) | |
629 | { | |
630 | sigset_t newmask, oldmask; | |
631 | int ret; | |
632 | ||
6ed4b2e6 | 633 | ret = sigfillset(&newmask); |
4cf1675f | 634 | assert(!ret); |
6ed4b2e6 | 635 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); |
4cf1675f MD |
636 | assert(!ret); |
637 | mutex_lock(&rcu_gp_lock); | |
731ccb96 | 638 | mutex_lock(&rcu_registry_lock); |
4cf1675f MD |
639 | saved_fork_signal_mask = oldmask; |
640 | } | |
641 | ||
642 | void rcu_bp_after_fork_parent(void) | |
643 | { | |
644 | sigset_t oldmask; | |
645 | int ret; | |
646 | ||
647 | oldmask = saved_fork_signal_mask; | |
731ccb96 | 648 | mutex_unlock(&rcu_registry_lock); |
4cf1675f MD |
649 | mutex_unlock(&rcu_gp_lock); |
650 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
651 | assert(!ret); | |
652 | } | |
653 | ||
c1be8fb9 MD |
654 | /* |
655 | * Prune all entries from registry except our own thread. Fits the Linux | |
731ccb96 | 656 | * fork behavior. Called with rcu_gp_lock and rcu_registry_lock held. |
c1be8fb9 MD |
657 | */ |
658 | static | |
659 | void urcu_bp_prune_registry(void) | |
660 | { | |
661 | struct registry_chunk *chunk; | |
662 | struct rcu_reader *rcu_reader_reg; | |
663 | ||
664 | cds_list_for_each_entry(chunk, ®istry_arena.chunk_list, node) { | |
665 | for (rcu_reader_reg = (struct rcu_reader *) &chunk->data[0]; | |
666 | rcu_reader_reg < (struct rcu_reader *) &chunk->data[chunk->data_len]; | |
667 | rcu_reader_reg++) { | |
668 | if (!rcu_reader_reg->alloc) | |
669 | continue; | |
670 | if (rcu_reader_reg->tid == pthread_self()) | |
671 | continue; | |
672 | cleanup_thread(chunk, rcu_reader_reg); | |
673 | } | |
674 | } | |
675 | } | |
676 | ||
4cf1675f MD |
677 | void rcu_bp_after_fork_child(void) |
678 | { | |
679 | sigset_t oldmask; | |
680 | int ret; | |
681 | ||
c1be8fb9 | 682 | urcu_bp_prune_registry(); |
4cf1675f | 683 | oldmask = saved_fork_signal_mask; |
731ccb96 | 684 | mutex_unlock(&rcu_registry_lock); |
4cf1675f MD |
685 | mutex_unlock(&rcu_gp_lock); |
686 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
687 | assert(!ret); | |
688 | } | |
5e77fc1f | 689 | |
9b7981bb MD |
690 | void *rcu_dereference_sym_bp(void *p) |
691 | { | |
692 | return _rcu_dereference(p); | |
693 | } | |
694 | ||
5efd3cd2 MD |
695 | void *rcu_set_pointer_sym_bp(void **p, void *v) |
696 | { | |
697 | cmm_wmb(); | |
424d4ed5 MD |
698 | uatomic_set(p, v); |
699 | return v; | |
5efd3cd2 MD |
700 | } |
701 | ||
702 | void *rcu_xchg_pointer_sym_bp(void **p, void *v) | |
703 | { | |
704 | cmm_wmb(); | |
705 | return uatomic_xchg(p, v); | |
706 | } | |
707 | ||
708 | void *rcu_cmpxchg_pointer_sym_bp(void **p, void *old, void *_new) | |
709 | { | |
710 | cmm_wmb(); | |
711 | return uatomic_cmpxchg(p, old, _new); | |
712 | } | |
713 | ||
5e6b23a6 | 714 | DEFINE_RCU_FLAVOR(rcu_flavor); |
541d828d | 715 | |
5e77fc1f | 716 | #include "urcu-call-rcu-impl.h" |
0376e7b2 | 717 | #include "urcu-defer-impl.h" |