1 /*
2 * Copyright (c) 2008-2012 Niels Provos, Nick Mathewson
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. The name of the author may not be used to endorse or promote products
13 * derived from this software without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26
27 #include "event2/event-config.h"
28 #include "evconfig-private.h"
29
30 #ifndef EVENT__DISABLE_THREAD_SUPPORT
31
32 #include "event2/thread.h"
33
34 #include <stdlib.h>
35 #include <string.h>
36
37 #include "log-internal.h"
38 #include "mm-internal.h"
39 #include "util-internal.h"
40 #include "evthread-internal.h"
41
42 #ifdef EVTHREAD_EXPOSE_STRUCTS
43 #define GLOBAL
44 #else
45 #define GLOBAL static
46 #endif
47
48 /* globals */
49 GLOBAL int evthread_lock_debugging_enabled_ = 0;
50 GLOBAL struct evthread_lock_callbacks evthread_lock_fns_ = {
51 0, 0, NULL, NULL, NULL, NULL
52 };
53 GLOBAL unsigned long (*evthread_id_fn_)(void) = NULL;
54 GLOBAL struct evthread_condition_callbacks evthread_cond_fns_ = {
55 0, NULL, NULL, NULL, NULL
56 };
57
58 /* Used for debugging */
59 static struct evthread_lock_callbacks original_lock_fns_ = {
60 0, 0, NULL, NULL, NULL, NULL
61 };
62 static struct evthread_condition_callbacks original_cond_fns_ = {
63 0, NULL, NULL, NULL, NULL
64 };
65
66 void
evthread_set_id_callback(unsigned long (* id_fn)(void))67 evthread_set_id_callback(unsigned long (*id_fn)(void))
68 {
69 evthread_id_fn_ = id_fn;
70 }
71
evthread_get_lock_callbacks()72 struct evthread_lock_callbacks *evthread_get_lock_callbacks()
73 {
74 return evthread_lock_debugging_enabled_
75 ? &original_lock_fns_ : &evthread_lock_fns_;
76 }
evthread_get_condition_callbacks()77 struct evthread_condition_callbacks *evthread_get_condition_callbacks()
78 {
79 return evthread_lock_debugging_enabled_
80 ? &original_cond_fns_ : &evthread_cond_fns_;
81 }
evthreadimpl_disable_lock_debugging_(void)82 void evthreadimpl_disable_lock_debugging_(void)
83 {
84 evthread_lock_debugging_enabled_ = 0;
85 }
86
87 int
evthread_set_lock_callbacks(const struct evthread_lock_callbacks * cbs)88 evthread_set_lock_callbacks(const struct evthread_lock_callbacks *cbs)
89 {
90 struct evthread_lock_callbacks *target = evthread_get_lock_callbacks();
91
92 if (!cbs) {
93 if (target->alloc)
94 event_warnx("Trying to disable lock functions after "
95 "they have been set up will probaby not work.");
96 memset(target, 0, sizeof(evthread_lock_fns_));
97 return 0;
98 }
99 if (target->alloc) {
100 /* Uh oh; we already had locking callbacks set up.*/
101 if (target->lock_api_version == cbs->lock_api_version &&
102 target->supported_locktypes == cbs->supported_locktypes &&
103 target->alloc == cbs->alloc &&
104 target->free == cbs->free &&
105 target->lock == cbs->lock &&
106 target->unlock == cbs->unlock) {
107 /* no change -- allow this. */
108 return 0;
109 }
110 event_warnx("Can't change lock callbacks once they have been "
111 "initialized.");
112 return -1;
113 }
114 if (cbs->alloc && cbs->free && cbs->lock && cbs->unlock) {
115 memcpy(target, cbs, sizeof(evthread_lock_fns_));
116 return event_global_setup_locks_(1);
117 } else {
118 return -1;
119 }
120 }
121
122 int
evthread_set_condition_callbacks(const struct evthread_condition_callbacks * cbs)123 evthread_set_condition_callbacks(const struct evthread_condition_callbacks *cbs)
124 {
125 struct evthread_condition_callbacks *target = evthread_get_condition_callbacks();
126
127 if (!cbs) {
128 if (target->alloc_condition)
129 event_warnx("Trying to disable condition functions "
130 "after they have been set up will probaby not "
131 "work.");
132 memset(target, 0, sizeof(evthread_cond_fns_));
133 return 0;
134 }
135 if (target->alloc_condition) {
136 /* Uh oh; we already had condition callbacks set up.*/
137 if (target->condition_api_version == cbs->condition_api_version &&
138 target->alloc_condition == cbs->alloc_condition &&
139 target->free_condition == cbs->free_condition &&
140 target->signal_condition == cbs->signal_condition &&
141 target->wait_condition == cbs->wait_condition) {
142 /* no change -- allow this. */
143 return 0;
144 }
145 event_warnx("Can't change condition callbacks once they "
146 "have been initialized.");
147 return -1;
148 }
149 if (cbs->alloc_condition && cbs->free_condition &&
150 cbs->signal_condition && cbs->wait_condition) {
151 memcpy(target, cbs, sizeof(evthread_cond_fns_));
152 }
153 if (evthread_lock_debugging_enabled_) {
154 evthread_cond_fns_.alloc_condition = cbs->alloc_condition;
155 evthread_cond_fns_.free_condition = cbs->free_condition;
156 evthread_cond_fns_.signal_condition = cbs->signal_condition;
157 }
158 return 0;
159 }
160
161 #define DEBUG_LOCK_SIG 0xdeb0b10c
162
163 struct debug_lock {
164 unsigned signature;
165 unsigned locktype;
166 unsigned long held_by;
167 /* XXXX if we ever use read-write locks, we will need a separate
168 * lock to protect count. */
169 int count;
170 void *lock;
171 };
172
173 static void *
debug_lock_alloc(unsigned locktype)174 debug_lock_alloc(unsigned locktype)
175 {
176 struct debug_lock *result = mm_malloc(sizeof(struct debug_lock));
177 if (!result)
178 return NULL;
179 if (original_lock_fns_.alloc) {
180 if (!(result->lock = original_lock_fns_.alloc(
181 locktype|EVTHREAD_LOCKTYPE_RECURSIVE))) {
182 mm_free(result);
183 return NULL;
184 }
185 } else {
186 result->lock = NULL;
187 }
188 result->signature = DEBUG_LOCK_SIG;
189 result->locktype = locktype;
190 result->count = 0;
191 result->held_by = 0;
192 return result;
193 }
194
195 static void
debug_lock_free(void * lock_,unsigned locktype)196 debug_lock_free(void *lock_, unsigned locktype)
197 {
198 struct debug_lock *lock = lock_;
199 EVUTIL_ASSERT(lock->count == 0);
200 EVUTIL_ASSERT(locktype == lock->locktype);
201 EVUTIL_ASSERT(DEBUG_LOCK_SIG == lock->signature);
202 if (original_lock_fns_.free) {
203 original_lock_fns_.free(lock->lock,
204 lock->locktype|EVTHREAD_LOCKTYPE_RECURSIVE);
205 }
206 lock->lock = NULL;
207 lock->count = -100;
208 lock->signature = 0x12300fda;
209 mm_free(lock);
210 }
211
212 static void
evthread_debug_lock_mark_locked(unsigned mode,struct debug_lock * lock)213 evthread_debug_lock_mark_locked(unsigned mode, struct debug_lock *lock)
214 {
215 EVUTIL_ASSERT(DEBUG_LOCK_SIG == lock->signature);
216 ++lock->count;
217 if (!(lock->locktype & EVTHREAD_LOCKTYPE_RECURSIVE))
218 EVUTIL_ASSERT(lock->count == 1);
219 if (evthread_id_fn_) {
220 unsigned long me;
221 me = evthread_id_fn_();
222 if (lock->count > 1)
223 EVUTIL_ASSERT(lock->held_by == me);
224 lock->held_by = me;
225 }
226 }
227
228 static int
debug_lock_lock(unsigned mode,void * lock_)229 debug_lock_lock(unsigned mode, void *lock_)
230 {
231 struct debug_lock *lock = lock_;
232 int res = 0;
233 if (lock->locktype & EVTHREAD_LOCKTYPE_READWRITE)
234 EVUTIL_ASSERT(mode & (EVTHREAD_READ|EVTHREAD_WRITE));
235 else
236 EVUTIL_ASSERT((mode & (EVTHREAD_READ|EVTHREAD_WRITE)) == 0);
237 if (original_lock_fns_.lock)
238 res = original_lock_fns_.lock(mode, lock->lock);
239 if (!res) {
240 evthread_debug_lock_mark_locked(mode, lock);
241 }
242 return res;
243 }
244
245 static void
evthread_debug_lock_mark_unlocked(unsigned mode,struct debug_lock * lock)246 evthread_debug_lock_mark_unlocked(unsigned mode, struct debug_lock *lock)
247 {
248 EVUTIL_ASSERT(DEBUG_LOCK_SIG == lock->signature);
249 if (lock->locktype & EVTHREAD_LOCKTYPE_READWRITE)
250 EVUTIL_ASSERT(mode & (EVTHREAD_READ|EVTHREAD_WRITE));
251 else
252 EVUTIL_ASSERT((mode & (EVTHREAD_READ|EVTHREAD_WRITE)) == 0);
253 if (evthread_id_fn_) {
254 unsigned long me;
255 me = evthread_id_fn_();
256 EVUTIL_ASSERT(lock->held_by == me);
257 if (lock->count == 1)
258 lock->held_by = 0;
259 }
260 --lock->count;
261 EVUTIL_ASSERT(lock->count >= 0);
262 }
263
264 static int
debug_lock_unlock(unsigned mode,void * lock_)265 debug_lock_unlock(unsigned mode, void *lock_)
266 {
267 struct debug_lock *lock = lock_;
268 int res = 0;
269 evthread_debug_lock_mark_unlocked(mode, lock);
270 if (original_lock_fns_.unlock)
271 res = original_lock_fns_.unlock(mode, lock->lock);
272 return res;
273 }
274
275 static int
debug_cond_wait(void * cond_,void * lock_,const struct timeval * tv)276 debug_cond_wait(void *cond_, void *lock_, const struct timeval *tv)
277 {
278 int r;
279 struct debug_lock *lock = lock_;
280 EVUTIL_ASSERT(lock);
281 EVUTIL_ASSERT(DEBUG_LOCK_SIG == lock->signature);
282 EVLOCK_ASSERT_LOCKED(lock_);
283 evthread_debug_lock_mark_unlocked(0, lock);
284 r = original_cond_fns_.wait_condition(cond_, lock->lock, tv);
285 evthread_debug_lock_mark_locked(0, lock);
286 return r;
287 }
288
289 /* misspelled version for backward compatibility */
290 void
evthread_enable_lock_debuging(void)291 evthread_enable_lock_debuging(void)
292 {
293 evthread_enable_lock_debugging();
294 }
295
296 void
evthread_enable_lock_debugging(void)297 evthread_enable_lock_debugging(void)
298 {
299 struct evthread_lock_callbacks cbs = {
300 EVTHREAD_LOCK_API_VERSION,
301 EVTHREAD_LOCKTYPE_RECURSIVE,
302 debug_lock_alloc,
303 debug_lock_free,
304 debug_lock_lock,
305 debug_lock_unlock
306 };
307 if (evthread_lock_debugging_enabled_)
308 return;
309 memcpy(&original_lock_fns_, &evthread_lock_fns_,
310 sizeof(struct evthread_lock_callbacks));
311 memcpy(&evthread_lock_fns_, &cbs,
312 sizeof(struct evthread_lock_callbacks));
313
314 memcpy(&original_cond_fns_, &evthread_cond_fns_,
315 sizeof(struct evthread_condition_callbacks));
316 evthread_cond_fns_.wait_condition = debug_cond_wait;
317 evthread_lock_debugging_enabled_ = 1;
318
319 /* XXX return value should get checked. */
320 event_global_setup_locks_(0);
321 }
322
323 int
evthread_is_debug_lock_held_(void * lock_)324 evthread_is_debug_lock_held_(void *lock_)
325 {
326 struct debug_lock *lock = lock_;
327 if (! lock->count)
328 return 0;
329 if (evthread_id_fn_) {
330 unsigned long me = evthread_id_fn_();
331 if (lock->held_by != me)
332 return 0;
333 }
334 return 1;
335 }
336
337 void *
evthread_debug_get_real_lock_(void * lock_)338 evthread_debug_get_real_lock_(void *lock_)
339 {
340 struct debug_lock *lock = lock_;
341 return lock->lock;
342 }
343
344 void *
evthread_setup_global_lock_(void * lock_,unsigned locktype,int enable_locks)345 evthread_setup_global_lock_(void *lock_, unsigned locktype, int enable_locks)
346 {
347 /* there are four cases here:
348 1) we're turning on debugging; locking is not on.
349 2) we're turning on debugging; locking is on.
350 3) we're turning on locking; debugging is not on.
351 4) we're turning on locking; debugging is on. */
352
353 if (!enable_locks && original_lock_fns_.alloc == NULL) {
354 /* Case 1: allocate a debug lock. */
355 EVUTIL_ASSERT(lock_ == NULL);
356 return debug_lock_alloc(locktype);
357 } else if (!enable_locks && original_lock_fns_.alloc != NULL) {
358 /* Case 2: wrap the lock in a debug lock. */
359 struct debug_lock *lock;
360 EVUTIL_ASSERT(lock_ != NULL);
361
362 if (!(locktype & EVTHREAD_LOCKTYPE_RECURSIVE)) {
363 /* We can't wrap it: We need a recursive lock */
364 original_lock_fns_.free(lock_, locktype);
365 return debug_lock_alloc(locktype);
366 }
367 lock = mm_malloc(sizeof(struct debug_lock));
368 if (!lock) {
369 original_lock_fns_.free(lock_, locktype);
370 return NULL;
371 }
372 lock->lock = lock_;
373 lock->locktype = locktype;
374 lock->count = 0;
375 lock->held_by = 0;
376 return lock;
377 } else if (enable_locks && ! evthread_lock_debugging_enabled_) {
378 /* Case 3: allocate a regular lock */
379 EVUTIL_ASSERT(lock_ == NULL);
380 return evthread_lock_fns_.alloc(locktype);
381 } else {
382 /* Case 4: Fill in a debug lock with a real lock */
383 struct debug_lock *lock = lock_;
384 EVUTIL_ASSERT(enable_locks &&
385 evthread_lock_debugging_enabled_);
386 EVUTIL_ASSERT(lock->locktype == locktype);
387 EVUTIL_ASSERT(lock->lock == NULL);
388 lock->lock = original_lock_fns_.alloc(
389 locktype|EVTHREAD_LOCKTYPE_RECURSIVE);
390 if (!lock->lock) {
391 lock->count = -200;
392 mm_free(lock);
393 return NULL;
394 }
395 return lock;
396 }
397 }
398
399
400 #ifndef EVTHREAD_EXPOSE_STRUCTS
401 unsigned long
evthreadimpl_get_id_()402 evthreadimpl_get_id_()
403 {
404 return evthread_id_fn_ ? evthread_id_fn_() : 1;
405 }
406 void *
evthreadimpl_lock_alloc_(unsigned locktype)407 evthreadimpl_lock_alloc_(unsigned locktype)
408 {
409 return evthread_lock_fns_.alloc ?
410 evthread_lock_fns_.alloc(locktype) : NULL;
411 }
412 void
evthreadimpl_lock_free_(void * lock,unsigned locktype)413 evthreadimpl_lock_free_(void *lock, unsigned locktype)
414 {
415 if (evthread_lock_fns_.free)
416 evthread_lock_fns_.free(lock, locktype);
417 }
418 int
evthreadimpl_lock_lock_(unsigned mode,void * lock)419 evthreadimpl_lock_lock_(unsigned mode, void *lock)
420 {
421 if (evthread_lock_fns_.lock)
422 return evthread_lock_fns_.lock(mode, lock);
423 else
424 return 0;
425 }
426 int
evthreadimpl_lock_unlock_(unsigned mode,void * lock)427 evthreadimpl_lock_unlock_(unsigned mode, void *lock)
428 {
429 if (evthread_lock_fns_.unlock)
430 return evthread_lock_fns_.unlock(mode, lock);
431 else
432 return 0;
433 }
434 void *
evthreadimpl_cond_alloc_(unsigned condtype)435 evthreadimpl_cond_alloc_(unsigned condtype)
436 {
437 return evthread_cond_fns_.alloc_condition ?
438 evthread_cond_fns_.alloc_condition(condtype) : NULL;
439 }
440 void
evthreadimpl_cond_free_(void * cond)441 evthreadimpl_cond_free_(void *cond)
442 {
443 if (evthread_cond_fns_.free_condition)
444 evthread_cond_fns_.free_condition(cond);
445 }
446 int
evthreadimpl_cond_signal_(void * cond,int broadcast)447 evthreadimpl_cond_signal_(void *cond, int broadcast)
448 {
449 if (evthread_cond_fns_.signal_condition)
450 return evthread_cond_fns_.signal_condition(cond, broadcast);
451 else
452 return 0;
453 }
454 int
evthreadimpl_cond_wait_(void * cond,void * lock,const struct timeval * tv)455 evthreadimpl_cond_wait_(void *cond, void *lock, const struct timeval *tv)
456 {
457 if (evthread_cond_fns_.wait_condition)
458 return evthread_cond_fns_.wait_condition(cond, lock, tv);
459 else
460 return 0;
461 }
462 int
evthreadimpl_is_lock_debugging_enabled_(void)463 evthreadimpl_is_lock_debugging_enabled_(void)
464 {
465 return evthread_lock_debugging_enabled_;
466 }
467
468 int
evthreadimpl_locking_enabled_(void)469 evthreadimpl_locking_enabled_(void)
470 {
471 return evthread_lock_fns_.lock != NULL;
472 }
473 #endif
474
475 #endif
476