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 | ||
0617bf4c | 26 | #define _GNU_SOURCE |
71c811bf | 27 | #define _LGPL_SOURCE |
fdee2e6d MD |
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> | |
37 | #include <sys/mman.h> | |
38 | ||
71c811bf | 39 | #include "urcu/wfqueue.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 | /* | |
89451e1b | 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 | { |
89451e1b MD |
76 | assert(!(flags & MREMAP_MAYMOVE)); |
77 | ||
78 | return MAP_FAILED; | |
45a4872f MD |
79 | } |
80 | #endif | |
81 | ||
fdee2e6d MD |
82 | /* Sleep delay in us */ |
83 | #define RCU_SLEEP_DELAY 1000 | |
89451e1b 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 | ||
e038e286 MD |
94 | static |
95 | void __attribute__((constructor)) rcu_bp_init(void); | |
96 | static | |
02be5561 | 97 | void __attribute__((destructor)) rcu_bp_exit(void); |
fdee2e6d | 98 | |
6abb4bd5 | 99 | static pthread_mutex_t rcu_gp_lock = PTHREAD_MUTEX_INITIALIZER; |
fdee2e6d | 100 | |
e038e286 MD |
101 | static pthread_mutex_t init_lock = PTHREAD_MUTEX_INITIALIZER; |
102 | static int initialized; | |
103 | ||
104 | static pthread_key_t urcu_bp_key; | |
105 | ||
fdee2e6d MD |
106 | #ifdef DEBUG_YIELD |
107 | unsigned int yield_active; | |
1745be1a | 108 | __DEFINE_URCU_TLS_GLOBAL(unsigned int, rand_yield); |
fdee2e6d MD |
109 | #endif |
110 | ||
111 | /* | |
112 | * Global grace period counter. | |
02be5561 | 113 | * Contains the current RCU_GP_CTR_PHASE. |
fdee2e6d MD |
114 | * Also has a RCU_GP_COUNT of 1, to accelerate the reader fast path. |
115 | * Written to only by writer with mutex taken. Read by both writer and readers. | |
116 | */ | |
02be5561 | 117 | long rcu_gp_ctr = RCU_GP_COUNT; |
fdee2e6d MD |
118 | |
119 | /* | |
120 | * Pointer to registry elements. Written to only by each individual reader. Read | |
121 | * by both the reader and the writers. | |
122 | */ | |
1745be1a | 123 | __DEFINE_URCU_TLS_GLOBAL(struct rcu_reader *, rcu_reader); |
fdee2e6d | 124 | |
16aa9ee8 | 125 | static CDS_LIST_HEAD(registry); |
fdee2e6d | 126 | |
89451e1b MD |
127 | struct registry_chunk { |
128 | size_t data_len; /* data length */ | |
e038e286 | 129 | size_t used; /* amount of data used */ |
89451e1b MD |
130 | struct cds_list_head node; /* chunk_list node */ |
131 | char data[]; | |
132 | }; | |
133 | ||
fdee2e6d | 134 | struct registry_arena { |
89451e1b | 135 | struct cds_list_head chunk_list; |
fdee2e6d MD |
136 | }; |
137 | ||
89451e1b MD |
138 | static struct registry_arena registry_arena = { |
139 | .chunk_list = CDS_LIST_HEAD_INIT(registry_arena.chunk_list), | |
140 | }; | |
fdee2e6d | 141 | |
4cf1675f MD |
142 | /* Saved fork signal mask, protected by rcu_gp_lock */ |
143 | static sigset_t saved_fork_signal_mask; | |
144 | ||
6abb4bd5 | 145 | static void mutex_lock(pthread_mutex_t *mutex) |
fdee2e6d MD |
146 | { |
147 | int ret; | |
148 | ||
149 | #ifndef DISTRUST_SIGNALS_EXTREME | |
6abb4bd5 | 150 | ret = pthread_mutex_lock(mutex); |
4a6d7378 MD |
151 | if (ret) |
152 | urcu_die(ret); | |
fdee2e6d | 153 | #else /* #ifndef DISTRUST_SIGNALS_EXTREME */ |
6abb4bd5 | 154 | while ((ret = pthread_mutex_trylock(mutex)) != 0) { |
4a6d7378 MD |
155 | if (ret != EBUSY && ret != EINTR) |
156 | urcu_die(ret); | |
fdee2e6d MD |
157 | poll(NULL,0,10); |
158 | } | |
159 | #endif /* #else #ifndef DISTRUST_SIGNALS_EXTREME */ | |
160 | } | |
161 | ||
6abb4bd5 | 162 | static void mutex_unlock(pthread_mutex_t *mutex) |
fdee2e6d MD |
163 | { |
164 | int ret; | |
165 | ||
6abb4bd5 | 166 | ret = pthread_mutex_unlock(mutex); |
4a6d7378 MD |
167 | if (ret) |
168 | urcu_die(ret); | |
fdee2e6d MD |
169 | } |
170 | ||
2dfb8b5e | 171 | void update_counter_and_wait(void) |
fdee2e6d | 172 | { |
16aa9ee8 | 173 | CDS_LIST_HEAD(qsreaders); |
fdee2e6d | 174 | int wait_loops = 0; |
02be5561 | 175 | struct rcu_reader *index, *tmp; |
fdee2e6d | 176 | |
32c15e4e | 177 | /* Switch parity: 0 -> 1, 1 -> 0 */ |
6cf3827c | 178 | CMM_STORE_SHARED(rcu_gp_ctr, rcu_gp_ctr ^ RCU_GP_CTR_PHASE); |
2dfb8b5e MD |
179 | |
180 | /* | |
181 | * Must commit qparity update to memory before waiting for other parity | |
182 | * quiescent state. Failure to do so could result in the writer waiting | |
183 | * forever while new readers are always accessing data (no progress). | |
6cf3827c | 184 | * Ensured by CMM_STORE_SHARED and CMM_LOAD_SHARED. |
2dfb8b5e MD |
185 | */ |
186 | ||
187 | /* | |
5481ddb3 | 188 | * Adding a cmm_smp_mb() which is _not_ formally required, but makes the |
2dfb8b5e MD |
189 | * model easier to understand. It does not have a big performance impact |
190 | * anyway, given this is the write-side. | |
191 | */ | |
5481ddb3 | 192 | cmm_smp_mb(); |
2dfb8b5e | 193 | |
fdee2e6d | 194 | /* |
02be5561 | 195 | * Wait for each thread rcu_reader.ctr count to become 0. |
fdee2e6d MD |
196 | */ |
197 | for (;;) { | |
198 | wait_loops++; | |
16aa9ee8 | 199 | cds_list_for_each_entry_safe(index, tmp, ®istry, node) { |
fdee2e6d | 200 | if (!rcu_old_gp_ongoing(&index->ctr)) |
16aa9ee8 | 201 | cds_list_move(&index->node, &qsreaders); |
fdee2e6d MD |
202 | } |
203 | ||
16aa9ee8 | 204 | if (cds_list_empty(®istry)) { |
fdee2e6d MD |
205 | break; |
206 | } else { | |
207 | if (wait_loops == RCU_QS_ACTIVE_ATTEMPTS) | |
208 | usleep(RCU_SLEEP_DELAY); | |
209 | else | |
06f22bdb | 210 | caa_cpu_relax(); |
fdee2e6d MD |
211 | } |
212 | } | |
213 | /* put back the reader list in the registry */ | |
16aa9ee8 | 214 | cds_list_splice(&qsreaders, ®istry); |
fdee2e6d MD |
215 | } |
216 | ||
217 | void synchronize_rcu(void) | |
218 | { | |
219 | sigset_t newmask, oldmask; | |
220 | int ret; | |
221 | ||
264716f7 | 222 | ret = sigfillset(&newmask); |
fdee2e6d | 223 | assert(!ret); |
264716f7 | 224 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); |
fdee2e6d MD |
225 | assert(!ret); |
226 | ||
6abb4bd5 | 227 | mutex_lock(&rcu_gp_lock); |
fdee2e6d | 228 | |
16aa9ee8 | 229 | if (cds_list_empty(®istry)) |
2dfb8b5e | 230 | goto out; |
fdee2e6d MD |
231 | |
232 | /* All threads should read qparity before accessing data structure | |
2dfb8b5e | 233 | * where new ptr points to. */ |
fdee2e6d | 234 | /* Write new ptr before changing the qparity */ |
5481ddb3 | 235 | cmm_smp_mb(); |
fdee2e6d | 236 | |
fdee2e6d MD |
237 | /* |
238 | * Wait for previous parity to be empty of readers. | |
239 | */ | |
2dfb8b5e | 240 | update_counter_and_wait(); /* 0 -> 1, wait readers in parity 0 */ |
fdee2e6d MD |
241 | |
242 | /* | |
5481ddb3 | 243 | * Adding a cmm_smp_mb() which is _not_ formally required, but makes the |
fdee2e6d MD |
244 | * model easier to understand. It does not have a big performance impact |
245 | * anyway, given this is the write-side. | |
246 | */ | |
5481ddb3 | 247 | cmm_smp_mb(); |
fdee2e6d | 248 | |
fdee2e6d | 249 | /* |
2dfb8b5e | 250 | * Wait for previous parity to be empty of readers. |
fdee2e6d | 251 | */ |
2dfb8b5e | 252 | update_counter_and_wait(); /* 1 -> 0, wait readers in parity 1 */ |
fdee2e6d MD |
253 | |
254 | /* | |
2dfb8b5e MD |
255 | * Finish waiting for reader threads before letting the old ptr being |
256 | * freed. | |
fdee2e6d | 257 | */ |
5481ddb3 | 258 | cmm_smp_mb(); |
2dfb8b5e | 259 | out: |
6abb4bd5 | 260 | mutex_unlock(&rcu_gp_lock); |
fdee2e6d MD |
261 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); |
262 | assert(!ret); | |
263 | } | |
264 | ||
265 | /* | |
266 | * library wrappers to be used by non-LGPL compatible source code. | |
267 | */ | |
268 | ||
269 | void rcu_read_lock(void) | |
270 | { | |
271 | _rcu_read_lock(); | |
272 | } | |
273 | ||
274 | void rcu_read_unlock(void) | |
275 | { | |
276 | _rcu_read_unlock(); | |
277 | } | |
278 | ||
279 | /* | |
89451e1b MD |
280 | * Only grow for now. If empty, allocate a ARENA_INIT_ALLOC sized chunk. |
281 | * Else, try expanding the last chunk. If this fails, allocate a new | |
282 | * chunk twice as big as the last chunk. | |
283 | * Memory used by chunks _never_ moves. A chunk could theoretically be | |
284 | * freed when all "used" slots are released, but we don't do it at this | |
285 | * point. | |
fdee2e6d | 286 | */ |
89451e1b MD |
287 | static |
288 | void expand_arena(struct registry_arena *arena) | |
fdee2e6d | 289 | { |
89451e1b MD |
290 | struct registry_chunk *new_chunk, *last_chunk; |
291 | size_t old_chunk_len, new_chunk_len; | |
292 | ||
293 | /* No chunk. */ | |
294 | if (cds_list_empty(&arena->chunk_list)) { | |
295 | assert(ARENA_INIT_ALLOC >= | |
296 | sizeof(struct registry_chunk) | |
297 | + sizeof(struct rcu_reader)); | |
298 | new_chunk_len = ARENA_INIT_ALLOC; | |
299 | new_chunk = mmap(NULL, new_chunk_len, | |
0bcbf365 MD |
300 | PROT_READ | PROT_WRITE, |
301 | MAP_ANONYMOUS | MAP_PRIVATE, | |
302 | -1, 0); | |
89451e1b MD |
303 | if (new_chunk == MAP_FAILED) |
304 | abort(); | |
305 | bzero(new_chunk, new_chunk_len); | |
306 | new_chunk->data_len = | |
307 | new_chunk_len - sizeof(struct registry_chunk); | |
308 | cds_list_add_tail(&new_chunk->node, &arena->chunk_list); | |
309 | return; /* We're done. */ | |
310 | } | |
0bcbf365 | 311 | |
89451e1b MD |
312 | /* Try expanding last chunk. */ |
313 | last_chunk = cds_list_entry(arena->chunk_list.prev, | |
314 | struct registry_chunk, node); | |
315 | old_chunk_len = | |
316 | last_chunk->data_len + sizeof(struct registry_chunk); | |
317 | new_chunk_len = old_chunk_len << 1; | |
318 | ||
319 | /* Don't allow memory mapping to move, just expand. */ | |
320 | new_chunk = mremap_wrapper(last_chunk, old_chunk_len, | |
321 | new_chunk_len, 0); | |
322 | if (new_chunk != MAP_FAILED) { | |
323 | /* Should not have moved. */ | |
324 | assert(new_chunk == last_chunk); | |
325 | bzero((char *) last_chunk + old_chunk_len, | |
326 | new_chunk_len - old_chunk_len); | |
327 | last_chunk->data_len = | |
328 | new_chunk_len - sizeof(struct registry_chunk); | |
329 | return; /* We're done. */ | |
330 | } | |
0617bf4c | 331 | |
89451e1b MD |
332 | /* Remap did not succeed, we need to add a new chunk. */ |
333 | new_chunk = mmap(NULL, new_chunk_len, | |
334 | PROT_READ | PROT_WRITE, | |
335 | MAP_ANONYMOUS | MAP_PRIVATE, | |
336 | -1, 0); | |
337 | if (new_chunk == MAP_FAILED) | |
338 | abort(); | |
339 | bzero(new_chunk, new_chunk_len); | |
340 | new_chunk->data_len = | |
341 | new_chunk_len - sizeof(struct registry_chunk); | |
342 | cds_list_add_tail(&new_chunk->node, &arena->chunk_list); | |
343 | } | |
344 | ||
345 | static | |
346 | struct rcu_reader *arena_alloc(struct registry_arena *arena) | |
347 | { | |
348 | struct registry_chunk *chunk; | |
349 | struct rcu_reader *rcu_reader_reg; | |
350 | int expand_done = 0; /* Only allow to expand once per alloc */ | |
351 | size_t len = sizeof(struct rcu_reader); | |
fdee2e6d | 352 | |
89451e1b MD |
353 | retry: |
354 | cds_list_for_each_entry(chunk, &arena->chunk_list, node) { | |
355 | if (chunk->data_len - chunk->used < len) | |
356 | continue; | |
357 | /* Find spot */ | |
358 | for (rcu_reader_reg = (struct rcu_reader *) &chunk->data[0]; | |
359 | rcu_reader_reg < (struct rcu_reader *) &chunk->data[chunk->data_len]; | |
360 | rcu_reader_reg++) { | |
361 | if (!rcu_reader_reg->alloc) { | |
362 | rcu_reader_reg->alloc = 1; | |
363 | chunk->used += len; | |
364 | return rcu_reader_reg; | |
365 | } | |
366 | } | |
367 | } | |
368 | ||
369 | if (!expand_done) { | |
370 | expand_arena(arena); | |
371 | expand_done = 1; | |
372 | goto retry; | |
373 | } | |
374 | ||
375 | return NULL; | |
fdee2e6d MD |
376 | } |
377 | ||
378 | /* Called with signals off and mutex locked */ | |
89451e1b MD |
379 | static |
380 | void add_thread(void) | |
fdee2e6d | 381 | { |
02be5561 | 382 | struct rcu_reader *rcu_reader_reg; |
e038e286 | 383 | int ret; |
fdee2e6d | 384 | |
89451e1b MD |
385 | rcu_reader_reg = arena_alloc(®istry_arena); |
386 | if (!rcu_reader_reg) | |
387 | abort(); | |
e038e286 MD |
388 | ret = pthread_setspecific(urcu_bp_key, rcu_reader_reg); |
389 | if (ret) | |
390 | abort(); | |
fdee2e6d MD |
391 | |
392 | /* Add to registry */ | |
02be5561 MD |
393 | rcu_reader_reg->tid = pthread_self(); |
394 | assert(rcu_reader_reg->ctr == 0); | |
16aa9ee8 | 395 | cds_list_add(&rcu_reader_reg->node, ®istry); |
89451e1b MD |
396 | /* |
397 | * Reader threads are pointing to the reader registry. This is | |
398 | * why its memory should never be relocated. | |
399 | */ | |
bd252a04 | 400 | URCU_TLS(rcu_reader) = rcu_reader_reg; |
fdee2e6d MD |
401 | } |
402 | ||
e038e286 MD |
403 | /* Called with mutex locked */ |
404 | static | |
405 | void cleanup_thread(struct registry_chunk *chunk, | |
406 | struct rcu_reader *rcu_reader_reg) | |
407 | { | |
408 | rcu_reader_reg->ctr = 0; | |
409 | cds_list_del(&rcu_reader_reg->node); | |
410 | rcu_reader_reg->tid = 0; | |
411 | rcu_reader_reg->alloc = 0; | |
412 | chunk->used -= sizeof(struct rcu_reader); | |
413 | } | |
414 | ||
415 | static | |
416 | struct registry_chunk *find_chunk(struct rcu_reader *rcu_reader_reg) | |
fdee2e6d | 417 | { |
89451e1b | 418 | struct registry_chunk *chunk; |
fdee2e6d | 419 | |
89451e1b | 420 | cds_list_for_each_entry(chunk, ®istry_arena.chunk_list, node) { |
e038e286 MD |
421 | if (rcu_reader_reg < (struct rcu_reader *) &chunk->data[0]) |
422 | continue; | |
423 | if (rcu_reader_reg >= (struct rcu_reader *) &chunk->data[chunk->data_len]) | |
424 | continue; | |
425 | return chunk; | |
426 | } | |
427 | return NULL; | |
428 | } | |
89451e1b | 429 | |
e038e286 MD |
430 | /* Called with signals off and mutex locked */ |
431 | static | |
432 | void remove_thread(void) | |
433 | { | |
434 | struct rcu_reader *rcu_reader_reg; | |
89451e1b | 435 | |
e038e286 MD |
436 | rcu_reader_reg = URCU_TLS(rcu_reader); |
437 | cleanup_thread(find_chunk(rcu_reader_reg), rcu_reader_reg); | |
438 | URCU_TLS(rcu_reader) = NULL; | |
fdee2e6d MD |
439 | } |
440 | ||
441 | /* Disable signals, take mutex, add to registry */ | |
442 | void rcu_bp_register(void) | |
443 | { | |
444 | sigset_t newmask, oldmask; | |
445 | int ret; | |
446 | ||
264716f7 | 447 | ret = sigfillset(&newmask); |
e038e286 MD |
448 | if (ret) |
449 | abort(); | |
264716f7 | 450 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); |
e038e286 MD |
451 | if (ret) |
452 | abort(); | |
fdee2e6d MD |
453 | |
454 | /* | |
455 | * Check if a signal concurrently registered our thread since | |
e038e286 MD |
456 | * the check in rcu_read_lock(). |
457 | */ | |
bd252a04 | 458 | if (URCU_TLS(rcu_reader)) |
fdee2e6d MD |
459 | goto end; |
460 | ||
e038e286 MD |
461 | /* |
462 | * Take care of early registration before urcu_bp constructor. | |
463 | */ | |
464 | rcu_bp_init(); | |
465 | ||
6abb4bd5 | 466 | mutex_lock(&rcu_gp_lock); |
fdee2e6d | 467 | add_thread(); |
6abb4bd5 | 468 | mutex_unlock(&rcu_gp_lock); |
fdee2e6d MD |
469 | end: |
470 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
e038e286 MD |
471 | if (ret) |
472 | abort(); | |
473 | } | |
474 | ||
475 | /* Disable signals, take mutex, remove from registry */ | |
476 | static | |
477 | void rcu_bp_unregister(void) | |
478 | { | |
479 | sigset_t newmask, oldmask; | |
480 | int ret; | |
481 | ||
482 | ret = sigfillset(&newmask); | |
483 | if (ret) | |
484 | abort(); | |
485 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); | |
486 | if (ret) | |
487 | abort(); | |
488 | ||
489 | mutex_lock(&rcu_gp_lock); | |
490 | remove_thread(); | |
491 | mutex_unlock(&rcu_gp_lock); | |
492 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
493 | if (ret) | |
494 | abort(); | |
495 | } | |
496 | ||
497 | /* | |
498 | * Remove thread from the registry when it exits, and flag it as | |
499 | * destroyed so garbage collection can take care of it. | |
500 | */ | |
501 | static | |
502 | void urcu_bp_thread_exit_notifier(void *rcu_key) | |
503 | { | |
504 | assert(rcu_key == URCU_TLS(rcu_reader)); | |
505 | rcu_bp_unregister(); | |
506 | } | |
507 | ||
508 | static | |
509 | void rcu_bp_init(void) | |
510 | { | |
511 | mutex_lock(&init_lock); | |
512 | if (!initialized) { | |
513 | int ret; | |
514 | ||
515 | ret = pthread_key_create(&urcu_bp_key, | |
516 | urcu_bp_thread_exit_notifier); | |
517 | if (ret) | |
518 | abort(); | |
519 | initialized = 1; | |
520 | } | |
521 | mutex_unlock(&init_lock); | |
fdee2e6d MD |
522 | } |
523 | ||
e038e286 | 524 | static |
9380711a | 525 | void rcu_bp_exit(void) |
fdee2e6d | 526 | { |
89451e1b | 527 | struct registry_chunk *chunk, *tmp; |
e038e286 | 528 | int ret; |
89451e1b MD |
529 | |
530 | cds_list_for_each_entry_safe(chunk, tmp, | |
531 | ®istry_arena.chunk_list, node) { | |
532 | munmap(chunk, chunk->data_len + sizeof(struct registry_chunk)); | |
533 | } | |
e038e286 MD |
534 | ret = pthread_key_delete(urcu_bp_key); |
535 | if (ret) | |
536 | abort(); | |
fdee2e6d | 537 | } |
4cf1675f MD |
538 | |
539 | /* | |
540 | * Holding the rcu_gp_lock across fork will make sure we fork() don't race with | |
541 | * a concurrent thread executing with this same lock held. This ensures that the | |
542 | * registry is in a coherent state in the child. | |
543 | */ | |
544 | void rcu_bp_before_fork(void) | |
545 | { | |
546 | sigset_t newmask, oldmask; | |
547 | int ret; | |
548 | ||
264716f7 | 549 | ret = sigfillset(&newmask); |
4cf1675f | 550 | assert(!ret); |
264716f7 | 551 | ret = pthread_sigmask(SIG_BLOCK, &newmask, &oldmask); |
4cf1675f MD |
552 | assert(!ret); |
553 | mutex_lock(&rcu_gp_lock); | |
554 | saved_fork_signal_mask = oldmask; | |
555 | } | |
556 | ||
557 | void rcu_bp_after_fork_parent(void) | |
558 | { | |
559 | sigset_t oldmask; | |
560 | int ret; | |
561 | ||
562 | oldmask = saved_fork_signal_mask; | |
563 | mutex_unlock(&rcu_gp_lock); | |
564 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
565 | assert(!ret); | |
566 | } | |
567 | ||
e038e286 MD |
568 | /* |
569 | * Prune all entries from registry except our own thread. Fits the Linux | |
570 | * fork behavior. Called with rcu_gp_lock held. | |
571 | */ | |
572 | static | |
573 | void urcu_bp_prune_registry(void) | |
574 | { | |
575 | struct registry_chunk *chunk; | |
576 | struct rcu_reader *rcu_reader_reg; | |
577 | ||
578 | cds_list_for_each_entry(chunk, ®istry_arena.chunk_list, node) { | |
579 | for (rcu_reader_reg = (struct rcu_reader *) &chunk->data[0]; | |
580 | rcu_reader_reg < (struct rcu_reader *) &chunk->data[chunk->data_len]; | |
581 | rcu_reader_reg++) { | |
582 | if (!rcu_reader_reg->alloc) | |
583 | continue; | |
584 | if (rcu_reader_reg->tid == pthread_self()) | |
585 | continue; | |
586 | cleanup_thread(chunk, rcu_reader_reg); | |
587 | } | |
588 | } | |
589 | } | |
590 | ||
4cf1675f MD |
591 | void rcu_bp_after_fork_child(void) |
592 | { | |
593 | sigset_t oldmask; | |
594 | int ret; | |
595 | ||
e038e286 | 596 | urcu_bp_prune_registry(); |
4cf1675f MD |
597 | oldmask = saved_fork_signal_mask; |
598 | mutex_unlock(&rcu_gp_lock); | |
599 | ret = pthread_sigmask(SIG_SETMASK, &oldmask, NULL); | |
600 | assert(!ret); | |
601 | } | |
5e77fc1f | 602 | |
9b7981bb MD |
603 | void *rcu_dereference_sym_bp(void *p) |
604 | { | |
605 | return _rcu_dereference(p); | |
606 | } | |
607 | ||
5efd3cd2 MD |
608 | void *rcu_set_pointer_sym_bp(void **p, void *v) |
609 | { | |
610 | cmm_wmb(); | |
424d4ed5 MD |
611 | uatomic_set(p, v); |
612 | return v; | |
5efd3cd2 MD |
613 | } |
614 | ||
615 | void *rcu_xchg_pointer_sym_bp(void **p, void *v) | |
616 | { | |
617 | cmm_wmb(); | |
618 | return uatomic_xchg(p, v); | |
619 | } | |
620 | ||
621 | void *rcu_cmpxchg_pointer_sym_bp(void **p, void *old, void *_new) | |
622 | { | |
623 | cmm_wmb(); | |
624 | return uatomic_cmpxchg(p, old, _new); | |
625 | } | |
626 | ||
5e6b23a6 | 627 | DEFINE_RCU_FLAVOR(rcu_flavor); |
541d828d | 628 | |
5e77fc1f | 629 | #include "urcu-call-rcu-impl.h" |
0376e7b2 | 630 | #include "urcu-defer-impl.h" |