Asterisk - The Open Source Telephony Project  21.4.1
lock.h
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1 /*
2  * Asterisk -- An open source telephony toolkit.
3  *
4  * Copyright (C) 1999 - 2010, Digium, Inc.
5  *
6  * Mark Spencer <markster@digium.com>
7  *
8  * See http://www.asterisk.org for more information about
9  * the Asterisk project. Please do not directly contact
10  * any of the maintainers of this project for assistance;
11  * the project provides a web site, mailing lists and IRC
12  * channels for your use.
13  *
14  * This program is free software, distributed under the terms of
15  * the GNU General Public License Version 2. See the LICENSE file
16  * at the top of the source tree.
17  */
18 
19 /*! \file
20  * \brief Asterisk locking-related definitions:
21  * - ast_mutex_t, ast_rwlock_t and related functions;
22  * - atomic arithmetic instructions;
23  * - wrappers for channel locking.
24  *
25  * - See \ref LockDef
26  */
27 
28 /*! \page LockDef Asterisk thread locking models
29  *
30  * This file provides different implementation of the functions,
31  * depending on the platform, the use of DEBUG_THREADS, and the way
32  * module-level mutexes are initialized.
33  *
34  * - \b static: the mutex is assigned the value AST_MUTEX_INIT_VALUE
35  * this is done at compile time, and is the way used on Linux.
36  * This method is not applicable to all platforms e.g. when the
37  * initialization needs that some code is run.
38  *
39  * - \b through constructors: for each mutex, a constructor function is
40  * defined, which then runs when the program (or the module)
41  * starts. The problem with this approach is that there is a
42  * lot of code duplication (a new block of code is created for
43  * each mutex). Also, it does not prevent a user from declaring
44  * a global mutex without going through the wrapper macros,
45  * so sane programming practices are still required.
46  */
47 
48 #ifndef _ASTERISK_LOCK_H
49 #define _ASTERISK_LOCK_H
50 
51 #include <pthread.h>
52 #include <time.h>
53 #include <sys/param.h>
54 #ifdef HAVE_BKTR
55 #include <execinfo.h>
56 #endif
57 
58 #ifndef HAVE_PTHREAD_RWLOCK_TIMEDWRLOCK
59 #include "asterisk/time.h"
60 #endif
61 
62 #include "asterisk/backtrace.h"
63 #include "asterisk/logger.h"
64 #include "asterisk/compiler.h"
65 
66 #define AST_PTHREADT_NULL (pthread_t) -1
67 #define AST_PTHREADT_STOP (pthread_t) -2
68 
69 #if (defined(SOLARIS) || defined(BSD))
70 #define AST_MUTEX_INIT_W_CONSTRUCTORS
71 #endif /* SOLARIS || BSD */
72 
73 /* Asterisk REQUIRES recursive (not error checking) mutexes
74  and will not run without them. */
75 #if defined(HAVE_PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP) && defined(HAVE_PTHREAD_MUTEX_RECURSIVE_NP)
76 #define PTHREAD_MUTEX_INIT_VALUE PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP
77 #define AST_MUTEX_KIND PTHREAD_MUTEX_RECURSIVE_NP
78 #else
79 #define PTHREAD_MUTEX_INIT_VALUE PTHREAD_MUTEX_INITIALIZER
80 #define AST_MUTEX_KIND PTHREAD_MUTEX_RECURSIVE
81 #endif /* PTHREAD_RECURSIVE_MUTEX_INITIALIZER_NP */
82 
83 #ifdef HAVE_PTHREAD_RWLOCK_INITIALIZER
84 #define __AST_RWLOCK_INIT_VALUE PTHREAD_RWLOCK_INITIALIZER
85 #else /* HAVE_PTHREAD_RWLOCK_INITIALIZER */
86 #define __AST_RWLOCK_INIT_VALUE {0}
87 #endif /* HAVE_PTHREAD_RWLOCK_INITIALIZER */
88 
89 #ifdef HAVE_BKTR
90 #define AST_LOCK_TRACK_INIT_VALUE { { NULL }, { 0 }, 0, { NULL }, { 0 }, {{{ 0 }}}, PTHREAD_MUTEX_INIT_VALUE }
91 #else
92 #define AST_LOCK_TRACK_INIT_VALUE { { NULL }, { 0 }, 0, { NULL }, { 0 }, PTHREAD_MUTEX_INIT_VALUE }
93 #endif
94 
95 #define AST_MUTEX_INIT_VALUE { PTHREAD_MUTEX_INIT_VALUE, NULL, {1, 0} }
96 #define AST_MUTEX_INIT_VALUE_NOTRACKING { PTHREAD_MUTEX_INIT_VALUE, NULL, {0, 0} }
97 
98 #define AST_RWLOCK_INIT_VALUE { __AST_RWLOCK_INIT_VALUE, NULL, {1, 0} }
99 #define AST_RWLOCK_INIT_VALUE_NOTRACKING { __AST_RWLOCK_INIT_VALUE, NULL, {0, 0} }
100 
101 #define AST_MAX_REENTRANCY 10
102 
103 struct ast_channel;
104 
105 /*!
106  * \brief Lock tracking information.
107  *
108  * \note Any changes to this struct MUST be reflected in the
109  * lock.c:restore_lock_tracking() function.
110  */
112  const char *file[AST_MAX_REENTRANCY];
113  int lineno[AST_MAX_REENTRANCY];
114  int reentrancy;
115  const char *func[AST_MAX_REENTRANCY];
116  pthread_t thread_id[AST_MAX_REENTRANCY];
117 #ifdef HAVE_BKTR
118  struct ast_bt backtrace[AST_MAX_REENTRANCY];
119 #endif
120  pthread_mutex_t reentr_mutex;
121 };
122 
124  /*! non-zero if lock tracking is enabled */
125  unsigned int tracking:1;
126  /*! non-zero if track is setup */
127  volatile unsigned int setup:1;
128 };
129 
130 /*! \brief Structure for mutex and tracking information.
131  *
132  * We have tracking information in this structure regardless of DEBUG_THREADS being enabled.
133  * The information will just be ignored in the core if a module does not request it..
134  */
136  pthread_mutex_t mutex;
137 #if !defined(DEBUG_THREADS) && !defined(DEBUG_THREADS_LOOSE_ABI) && \
138  !defined(DETECT_DEADLOCKS)
139  /*!
140  * These fields are renamed to ensure they are never used when
141  * DEBUG_THREADS is not defined.
142  */
144  struct ast_lock_track_flags _flags;
145 #elif defined(DEBUG_THREADS) || defined(DETECT_DEADLOCKS)
146  /*! Track which thread holds this mutex. */
147  struct ast_lock_track *track;
148  struct ast_lock_track_flags flags;
149 #endif
150 };
151 
152 /*! \brief Structure for rwlock and tracking information.
153  *
154  * We have tracking information in this structure regardless of DEBUG_THREADS being enabled.
155  * The information will just be ignored in the core if a module does not request it..
156  */
158  pthread_rwlock_t lock;
159 #if !defined(DEBUG_THREADS) && !defined(DEBUG_THREADS_LOOSE_ABI) && \
160  !defined(DETECT_DEADLOCKS)
161  /*!
162  * These fields are renamed to ensure they are never used when
163  * DEBUG_THREADS is not defined.
164  */
166  struct ast_lock_track_flags _flags;
167 #elif defined(DEBUG_THREADS) || defined(DETECT_DEADLOCKS)
168  /*! Track which thread holds this lock */
169  struct ast_lock_track *track;
170  struct ast_lock_track_flags flags;
171 #endif
172 };
173 
174 typedef struct ast_mutex_info ast_mutex_t;
175 
176 typedef struct ast_rwlock_info ast_rwlock_t;
177 
178 typedef pthread_cond_t ast_cond_t;
179 
180 int __ast_pthread_mutex_init(int tracking, const char *filename, int lineno, const char *func, const char *mutex_name, ast_mutex_t *t);
181 int __ast_pthread_mutex_destroy(const char *filename, int lineno, const char *func, const char *mutex_name, ast_mutex_t *t);
182 int __ast_pthread_mutex_lock(const char *filename, int lineno, const char *func, const char* mutex_name, ast_mutex_t *t);
183 int __ast_pthread_mutex_trylock(const char *filename, int lineno, const char *func, const char* mutex_name, ast_mutex_t *t);
184 int __ast_pthread_mutex_unlock(const char *filename, int lineno, const char *func, const char *mutex_name, ast_mutex_t *t);
185 
186 #define ast_mutex_init(pmutex) __ast_pthread_mutex_init(1, __FILE__, __LINE__, __PRETTY_FUNCTION__, #pmutex, pmutex)
187 #define ast_mutex_init_notracking(pmutex) __ast_pthread_mutex_init(0, __FILE__, __LINE__, __PRETTY_FUNCTION__, #pmutex, pmutex)
188 #define ast_mutex_destroy(a) __ast_pthread_mutex_destroy(__FILE__, __LINE__, __PRETTY_FUNCTION__, #a, a)
189 #define ast_mutex_lock(a) __ast_pthread_mutex_lock(__FILE__, __LINE__, __PRETTY_FUNCTION__, #a, a)
190 #define ast_mutex_unlock(a) __ast_pthread_mutex_unlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, #a, a)
191 #define ast_mutex_trylock(a) __ast_pthread_mutex_trylock(__FILE__, __LINE__, __PRETTY_FUNCTION__, #a, a)
192 
193 
194 int __ast_cond_init(const char *filename, int lineno, const char *func, const char *cond_name, ast_cond_t *cond, pthread_condattr_t *cond_attr);
195 int __ast_cond_signal(const char *filename, int lineno, const char *func, const char *cond_name, ast_cond_t *cond);
196 int __ast_cond_broadcast(const char *filename, int lineno, const char *func, const char *cond_name, ast_cond_t *cond);
197 int __ast_cond_destroy(const char *filename, int lineno, const char *func, const char *cond_name, ast_cond_t *cond);
198 int __ast_cond_wait(const char *filename, int lineno, const char *func, const char *cond_name, const char *mutex_name, ast_cond_t *cond, ast_mutex_t *t);
199 int __ast_cond_timedwait(const char *filename, int lineno, const char *func, const char *cond_name, const char *mutex_name, ast_cond_t *cond, ast_mutex_t *t, const struct timespec *abstime);
200 
201 #define ast_cond_init(cond, attr) __ast_cond_init(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, cond, attr)
202 #define ast_cond_destroy(cond) __ast_cond_destroy(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, cond)
203 #define ast_cond_signal(cond) __ast_cond_signal(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, cond)
204 #define ast_cond_broadcast(cond) __ast_cond_broadcast(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, cond)
205 #define ast_cond_wait(cond, mutex) __ast_cond_wait(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, #mutex, cond, mutex)
206 #define ast_cond_timedwait(cond, mutex, time) __ast_cond_timedwait(__FILE__, __LINE__, __PRETTY_FUNCTION__, #cond, #mutex, cond, mutex, time)
207 
208 
209 int __ast_rwlock_init(int tracking, const char *filename, int lineno, const char *func, const char *rwlock_name, ast_rwlock_t *t);
210 int __ast_rwlock_destroy(const char *filename, int lineno, const char *func, const char *rwlock_name, ast_rwlock_t *t);
211 int __ast_rwlock_unlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name);
212 int __ast_rwlock_rdlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name);
213 int __ast_rwlock_wrlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name);
214 int __ast_rwlock_timedrdlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name, const struct timespec *abs_timeout);
215 int __ast_rwlock_timedwrlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name, const struct timespec *abs_timeout);
216 int __ast_rwlock_tryrdlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name);
217 int __ast_rwlock_trywrlock(const char *filename, int lineno, const char *func, ast_rwlock_t *t, const char *name);
218 
219 /*!
220  * \brief wrapper for rwlock with tracking enabled
221  * \return 0 on success, non zero for error
222  * \since 1.6.1
223  */
224 #define ast_rwlock_init(rwlock) __ast_rwlock_init(1, __FILE__, __LINE__, __PRETTY_FUNCTION__, #rwlock, rwlock)
225 
226 /*!
227  * \brief wrapper for ast_rwlock_init with tracking disabled
228  * \return 0 on success, non zero for error
229  * \since 1.6.1
230  */
231 #define ast_rwlock_init_notracking(rwlock) __ast_rwlock_init(0, __FILE__, __LINE__, __PRETTY_FUNCTION__, #rwlock, rwlock)
232 
233 #define ast_rwlock_destroy(rwlock) __ast_rwlock_destroy(__FILE__, __LINE__, __PRETTY_FUNCTION__, #rwlock, rwlock)
234 #define ast_rwlock_unlock(a) __ast_rwlock_unlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a)
235 #define ast_rwlock_rdlock(a) __ast_rwlock_rdlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a)
236 #define ast_rwlock_wrlock(a) __ast_rwlock_wrlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a)
237 #define ast_rwlock_tryrdlock(a) __ast_rwlock_tryrdlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a)
238 #define ast_rwlock_trywrlock(a) __ast_rwlock_trywrlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a)
239 #define ast_rwlock_timedrdlock(a, b) __ast_rwlock_timedrdlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a, b)
240 #define ast_rwlock_timedwrlock(a, b) __ast_rwlock_timedwrlock(__FILE__, __LINE__, __PRETTY_FUNCTION__, a, #a, b)
241 
242 #define ROFFSET ((lt->reentrancy > 0) ? (lt->reentrancy-1) : 0)
243 
244 #ifdef DEBUG_THREADS
245 
246 #ifdef THREAD_CRASH
247 #define DO_THREAD_CRASH do { *((int *)(0)) = 1; } while(0)
248 #else
249 #define DO_THREAD_CRASH do { } while (0)
250 #endif
251 
252 #include <errno.h>
253 
254 enum ast_lock_type {
255  AST_MUTEX,
256  AST_RDLOCK,
257  AST_WRLOCK,
258 };
259 
260 /*!
261  * \brief Store lock info for the current thread
262  *
263  * This function gets called in ast_mutex_lock() and ast_mutex_trylock() so
264  * that information about this lock can be stored in this thread's
265  * lock info struct. The lock is marked as pending as the thread is waiting
266  * on the lock. ast_mark_lock_acquired() will mark it as held by this thread.
267  */
268 void ast_store_lock_info(enum ast_lock_type type, const char *filename,
269  int line_num, const char *func, const char *lock_name, void *lock_addr, struct ast_bt *bt);
270 
271 /*!
272  * \brief Mark the last lock as acquired
273  */
274 void ast_mark_lock_acquired(void *lock_addr);
275 
276 /*!
277  * \brief Mark the last lock as failed (trylock)
278  */
279 void ast_mark_lock_failed(void *lock_addr);
280 
281 /*!
282  * \brief remove lock info for the current thread
283  *
284  * this gets called by ast_mutex_unlock so that information on the lock can
285  * be removed from the current thread's lock info struct.
286  */
287 void ast_remove_lock_info(void *lock_addr, struct ast_bt *bt);
288 void ast_suspend_lock_info(void *lock_addr);
289 void ast_restore_lock_info(void *lock_addr);
290 
291 /*!
292  * \brief log info for the current lock with ast_log().
293  *
294  * this function would be mostly for debug. If you come across a lock
295  * that is unexpectedly but momentarily locked, and you wonder who
296  * are fighting with for the lock, this routine could be called, IF
297  * you have the thread debugging stuff turned on.
298  * \param this_lock_addr lock address to return lock information
299  * \since 1.6.1
300  */
301 void ast_log_show_lock(void *this_lock_addr);
302 
303 /*!
304  * \brief Generate a lock dump equivalent to "core show locks".
305  *
306  * The lock dump generated is generally too large to be output by a
307  * single ast_verbose/log/debug/etc. call. Only ast_cli() handles it
308  * properly without changing BUFSIZ in logger.c.
309  *
310  * Note: This must be ast_free()d when you're done with it.
311  *
312  * \retval An ast_str containing the lock dump
313  * \retval NULL on error
314  * \since 12
315  */
316 struct ast_str *ast_dump_locks(void);
317 
318 /*!
319  * \brief retrieve lock info for the specified mutex
320  *
321  * this gets called during deadlock avoidance, so that the information may
322  * be preserved as to what location originally acquired the lock.
323  */
324 int ast_find_lock_info(void *lock_addr, char *filename, size_t filename_size, int *lineno, char *func, size_t func_size, char *mutex_name, size_t mutex_name_size);
325 
326 /*!
327  * \brief Unlock a lock briefly
328  *
329  * used during deadlock avoidance, to preserve the original location where
330  * a lock was originally acquired.
331  */
332 #define AO2_DEADLOCK_AVOIDANCE(obj) \
333  do { \
334  char __filename[80], __func[80], __mutex_name[80]; \
335  int __lineno; \
336  int __res = ast_find_lock_info(ao2_object_get_lockaddr(obj), __filename, sizeof(__filename), &__lineno, __func, sizeof(__func), __mutex_name, sizeof(__mutex_name)); \
337  int __res2 = ao2_unlock(obj); \
338  usleep(1); \
339  if (__res < 0) { /* Could happen if the ao2 object does not have a mutex. */ \
340  if (__res2) { \
341  ast_log(LOG_WARNING, "Could not unlock ao2 object '%s': %s and no lock info found! I will NOT try to relock.\n", #obj, strerror(__res2)); \
342  } else { \
343  ao2_lock(obj); \
344  } \
345  } else { \
346  if (__res2) { \
347  ast_log(LOG_WARNING, "Could not unlock ao2 object '%s': %s. {{{Originally locked at %s line %d: (%s) '%s'}}} I will NOT try to relock.\n", #obj, strerror(__res2), __filename, __lineno, __func, __mutex_name); \
348  } else { \
349  __ao2_lock(obj, AO2_LOCK_REQ_MUTEX, __filename, __func, __lineno, __mutex_name); \
350  } \
351  } \
352  } while (0)
353 
354 #define CHANNEL_DEADLOCK_AVOIDANCE(chan) \
355  do { \
356  char __filename[80], __func[80], __mutex_name[80]; \
357  int __lineno; \
358  int __res = ast_find_lock_info(ao2_object_get_lockaddr(chan), __filename, sizeof(__filename), &__lineno, __func, sizeof(__func), __mutex_name, sizeof(__mutex_name)); \
359  int __res2 = ast_channel_unlock(chan); \
360  usleep(1); \
361  if (__res < 0) { /* Shouldn't ever happen, but just in case... */ \
362  if (__res2) { \
363  ast_log(LOG_WARNING, "Could not unlock channel '%s': %s and no lock info found! I will NOT try to relock.\n", #chan, strerror(__res2)); \
364  } else { \
365  ast_channel_lock(chan); \
366  } \
367  } else { \
368  if (__res2) { \
369  ast_log(LOG_WARNING, "Could not unlock channel '%s': %s. {{{Originally locked at %s line %d: (%s) '%s'}}} I will NOT try to relock.\n", #chan, strerror(__res2), __filename, __lineno, __func, __mutex_name); \
370  } else { \
371  __ao2_lock(chan, AO2_LOCK_REQ_MUTEX, __filename, __func, __lineno, __mutex_name); \
372  } \
373  } \
374  } while (0)
375 
376 #define DEADLOCK_AVOIDANCE(lock) \
377  do { \
378  char __filename[80], __func[80], __mutex_name[80]; \
379  int __lineno; \
380  int __res = ast_find_lock_info(lock, __filename, sizeof(__filename), &__lineno, __func, sizeof(__func), __mutex_name, sizeof(__mutex_name)); \
381  int __res2 = ast_mutex_unlock(lock); \
382  usleep(1); \
383  if (__res < 0) { /* Shouldn't ever happen, but just in case... */ \
384  if (__res2 == 0) { \
385  ast_mutex_lock(lock); \
386  } else { \
387  ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s and no lock info found! I will NOT try to relock.\n", #lock, strerror(__res2)); \
388  } \
389  } else { \
390  if (__res2 == 0) { \
391  __ast_pthread_mutex_lock(__filename, __lineno, __func, __mutex_name, lock); \
392  } else { \
393  ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s. {{{Originally locked at %s line %d: (%s) '%s'}}} I will NOT try to relock.\n", #lock, strerror(__res2), __filename, __lineno, __func, __mutex_name); \
394  } \
395  } \
396  } while (0)
397 
398 /*!
399  * \brief Deadlock avoidance unlock
400  *
401  * In certain deadlock avoidance scenarios, there is more than one lock to be
402  * unlocked and relocked. Therefore, this pair of macros is provided for that
403  * purpose. Note that every DLA_UNLOCK _MUST_ be paired with a matching
404  * DLA_LOCK. The intent of this pair of macros is to be used around another
405  * set of deadlock avoidance code, mainly CHANNEL_DEADLOCK_AVOIDANCE, as the
406  * locking order specifies that we may safely lock a channel, followed by its
407  * pvt, with no worries about a deadlock. In any other scenario, this macro
408  * may not be safe to use.
409  */
410 #define DLA_UNLOCK(lock) \
411  do { \
412  char __filename[80], __func[80], __mutex_name[80]; \
413  int __lineno; \
414  int __res = ast_find_lock_info(lock, __filename, sizeof(__filename), &__lineno, __func, sizeof(__func), __mutex_name, sizeof(__mutex_name)); \
415  int __res2 = ast_mutex_unlock(lock);
416 
417 /*!
418  * \brief Deadlock avoidance lock
419  *
420  * In certain deadlock avoidance scenarios, there is more than one lock to be
421  * unlocked and relocked. Therefore, this pair of macros is provided for that
422  * purpose. Note that every DLA_UNLOCK _MUST_ be paired with a matching
423  * DLA_LOCK. The intent of this pair of macros is to be used around another
424  * set of deadlock avoidance code, mainly CHANNEL_DEADLOCK_AVOIDANCE, as the
425  * locking order specifies that we may safely lock a channel, followed by its
426  * pvt, with no worries about a deadlock. In any other scenario, this macro
427  * may not be safe to use.
428  */
429 #define DLA_LOCK(lock) \
430  if (__res < 0) { /* Shouldn't ever happen, but just in case... */ \
431  if (__res2) { \
432  ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s and no lock info found! I will NOT try to relock.\n", #lock, strerror(__res2)); \
433  } else { \
434  ast_mutex_lock(lock); \
435  } \
436  } else { \
437  if (__res2) { \
438  ast_log(LOG_WARNING, "Could not unlock mutex '%s': %s. {{{Originally locked at %s line %d: (%s) '%s'}}} I will NOT try to relock.\n", #lock, strerror(__res2), __filename, __lineno, __func, __mutex_name); \
439  } else { \
440  __ast_pthread_mutex_lock(__filename, __lineno, __func, __mutex_name, lock); \
441  } \
442  } \
443  } while (0)
444 
445 static inline void ast_reentrancy_lock(struct ast_lock_track *lt)
446 {
447  int res;
448  if ((res = pthread_mutex_lock(&lt->reentr_mutex))) {
449  fprintf(stderr, "ast_reentrancy_lock failed: '%s' (%d)\n", strerror(res), res);
450 #if defined(DO_CRASH) || defined(THREAD_CRASH)
451  abort();
452 #endif
453  }
454 }
455 
456 static inline void ast_reentrancy_unlock(struct ast_lock_track *lt)
457 {
458  int res;
459  if ((res = pthread_mutex_unlock(&lt->reentr_mutex))) {
460  fprintf(stderr, "ast_reentrancy_unlock failed: '%s' (%d)\n", strerror(res), res);
461 #if defined(DO_CRASH) || defined(THREAD_CRASH)
462  abort();
463 #endif
464  }
465 }
466 
467 #else /* !DEBUG_THREADS */
468 
469 #define AO2_DEADLOCK_AVOIDANCE(obj) \
470  ao2_unlock(obj); \
471  usleep(1); \
472  ao2_lock(obj);
473 
474 #define CHANNEL_DEADLOCK_AVOIDANCE(chan) \
475  ast_channel_unlock(chan); \
476  usleep(1); \
477  ast_channel_lock(chan);
478 
479 #define DEADLOCK_AVOIDANCE(lock) \
480  do { \
481  int __res; \
482  if (!(__res = ast_mutex_unlock(lock))) { \
483  usleep(1); \
484  ast_mutex_lock(lock); \
485  } else { \
486  ast_log(LOG_WARNING, "Failed to unlock mutex '%s' (%s). I will NOT try to relock. {{{ THIS IS A BUG. }}}\n", #lock, strerror(__res)); \
487  } \
488  } while (0)
489 
490 #define DLA_UNLOCK(lock) ast_mutex_unlock(lock)
491 
492 #define DLA_LOCK(lock) ast_mutex_lock(lock)
493 
494 #endif /* !DEBUG_THREADS */
495 
496 #if defined(AST_MUTEX_INIT_W_CONSTRUCTORS)
497 /*
498  * If AST_MUTEX_INIT_W_CONSTRUCTORS is defined, use file scope constructors
499  * and destructors to create/destroy global mutexes.
500  */
501 #define __AST_MUTEX_DEFINE(scope, mutex, init_val, track) \
502  scope ast_mutex_t mutex = init_val; \
503 static void __attribute__((constructor)) init_##mutex(void) \
504 { \
505  if (track) \
506  ast_mutex_init(&mutex); \
507  else \
508  ast_mutex_init_notracking(&mutex); \
509 } \
510  \
511 static void __attribute__((destructor)) fini_##mutex(void) \
512 { \
513  ast_mutex_destroy(&mutex); \
514 }
515 #else /* !AST_MUTEX_INIT_W_CONSTRUCTORS */
516 /* By default, use static initialization of mutexes. */
517 #define __AST_MUTEX_DEFINE(scope, mutex, init_val, track) scope ast_mutex_t mutex = init_val
518 #endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
519 
520 #define AST_MUTEX_DEFINE_STATIC(mutex) __AST_MUTEX_DEFINE(static, mutex, AST_MUTEX_INIT_VALUE, 1)
521 #define AST_MUTEX_DEFINE_STATIC_NOTRACKING(mutex) __AST_MUTEX_DEFINE(static, mutex, AST_MUTEX_INIT_VALUE_NOTRACKING, 0)
522 
523 
524 /* Statically declared read/write locks */
525 #ifdef AST_MUTEX_INIT_W_CONSTRUCTORS
526 #define __AST_RWLOCK_DEFINE(scope, rwlock, init_val, track) \
527  scope ast_rwlock_t rwlock = init_val; \
528 static void __attribute__((constructor)) init_##rwlock(void) \
529 { \
530  if (track) \
531  ast_rwlock_init(&rwlock); \
532  else \
533  ast_rwlock_init_notracking(&rwlock); \
534 } \
535 static void __attribute__((destructor)) fini_##rwlock(void) \
536 { \
537  ast_rwlock_destroy(&rwlock); \
538 }
539 #else
540 #define __AST_RWLOCK_DEFINE(scope, rwlock, init_val, track) scope ast_rwlock_t rwlock = init_val
541 #endif
542 
543 #define AST_RWLOCK_DEFINE_STATIC(rwlock) __AST_RWLOCK_DEFINE(static, rwlock, AST_RWLOCK_INIT_VALUE, 1)
544 #define AST_RWLOCK_DEFINE_STATIC_NOTRACKING(rwlock) __AST_RWLOCK_DEFINE(static, rwlock, AST_RWLOCK_INIT_VALUE_NOTRACKING, 0)
545 
546 /*!
547  * \brief Scoped Locks
548  *
549  * Scoped locks provide a way to use RAII locks. In other words,
550  * declaration of a scoped lock will automatically define and lock
551  * the lock. When the lock goes out of scope, it will automatically
552  * be unlocked.
553  *
554  * \code
555  * int some_function(struct ast_channel *chan)
556  * {
557  * SCOPED_LOCK(lock, chan, ast_channel_lock, ast_channel_unlock);
558  *
559  * if (!strcmp(ast_channel_name(chan, "foo")) {
560  * return 0;
561  * }
562  *
563  * return -1;
564  * }
565  * \endcode
566  *
567  * In the above example, neither return path requires explicit unlocking
568  * of the channel.
569  *
570  * \note
571  * Care should be taken when using SCOPED_LOCKS in conjunction with ao2 objects.
572  * ao2 objects should be unlocked before they are unreffed. Since SCOPED_LOCK runs
573  * once the variable goes out of scope, this can easily lead to situations where the
574  * variable gets unlocked after it is unreffed.
575  *
576  * \param varname The unique name to give to the scoped lock. You are not likely to reference
577  * this outside of the SCOPED_LOCK invocation.
578  * \param lock The variable to lock. This can be anything that can be passed to a locking
579  * or unlocking function.
580  * \param lockfunc The function to call to lock the lock
581  * \param unlockfunc The function to call to unlock the lock
582  */
583 #define SCOPED_LOCK(varname, lock, lockfunc, unlockfunc) \
584  RAII_VAR(typeof((lock)), varname, ({lockfunc((lock)); (lock); }), unlockfunc)
585 
586 /*!
587  * \brief scoped lock specialization for mutexes
588  */
589 #define SCOPED_MUTEX(varname, lock) SCOPED_LOCK(varname, (lock), ast_mutex_lock, ast_mutex_unlock)
590 
591 /*!
592  * \brief scoped lock specialization for read locks
593  */
594 #define SCOPED_RDLOCK(varname, lock) SCOPED_LOCK(varname, (lock), ast_rwlock_rdlock, ast_rwlock_unlock)
595 
596 /*!
597  * \brief scoped lock specialization for write locks
598  */
599 #define SCOPED_WRLOCK(varname, lock) SCOPED_LOCK(varname, (lock), ast_rwlock_wrlock, ast_rwlock_unlock)
600 
601 /*!
602  * \brief scoped lock specialization for ao2 mutexes.
603  */
604 #define SCOPED_AO2LOCK(varname, obj) SCOPED_LOCK(varname, (obj), ao2_lock, ao2_unlock)
605 
606 /*!
607  * \brief scoped lock specialization for ao2 read locks.
608  */
609 #define SCOPED_AO2RDLOCK(varname, obj) SCOPED_LOCK(varname, (obj), ao2_rdlock, ao2_unlock)
610 
611 /*!
612  * \brief scoped lock specialization for ao2 write locks.
613  */
614 #define SCOPED_AO2WRLOCK(varname, obj) SCOPED_LOCK(varname, (obj), ao2_wrlock, ao2_unlock)
615 
616 /*!
617  * \brief scoped lock specialization for channels.
618  */
619 #define SCOPED_CHANNELLOCK(varname, chan) SCOPED_LOCK(varname, (chan), ast_channel_lock, ast_channel_unlock)
620 
621 #ifndef __CYGWIN__ /* temporary disabled for cygwin */
622 #define pthread_mutex_t use_ast_mutex_t_instead_of_pthread_mutex_t
623 #define pthread_cond_t use_ast_cond_t_instead_of_pthread_cond_t
624 #endif
625 #define pthread_mutex_lock use_ast_mutex_lock_instead_of_pthread_mutex_lock
626 #define pthread_mutex_unlock use_ast_mutex_unlock_instead_of_pthread_mutex_unlock
627 #define pthread_mutex_trylock use_ast_mutex_trylock_instead_of_pthread_mutex_trylock
628 #define pthread_mutex_init use_ast_mutex_init_instead_of_pthread_mutex_init
629 #define pthread_mutex_destroy use_ast_mutex_destroy_instead_of_pthread_mutex_destroy
630 #define pthread_cond_init use_ast_cond_init_instead_of_pthread_cond_init
631 #define pthread_cond_destroy use_ast_cond_destroy_instead_of_pthread_cond_destroy
632 #define pthread_cond_signal use_ast_cond_signal_instead_of_pthread_cond_signal
633 #define pthread_cond_broadcast use_ast_cond_broadcast_instead_of_pthread_cond_broadcast
634 #define pthread_cond_wait use_ast_cond_wait_instead_of_pthread_cond_wait
635 #define pthread_cond_timedwait use_ast_cond_timedwait_instead_of_pthread_cond_timedwait
636 
637 #define AST_MUTEX_INITIALIZER __use_AST_MUTEX_DEFINE_STATIC_rather_than_AST_MUTEX_INITIALIZER__
638 
639 #define gethostbyname __gethostbyname__is__not__reentrant__use__ast_gethostbyname__instead__
640 
641 #ifndef __linux__
642 #define pthread_create __use_ast_pthread_create_instead__
643 #endif
644 
645 /*!
646  * \brief Support for atomic instructions.
647  *
648  * These macros implement a uniform interface to use built-in atomic functionality.
649  * If available __atomic built-ins are prefered. Legacy __sync built-ins are used
650  * as a fallback for older compilers.
651  *
652  * Detailed documentation can be found in the GCC manual, all API's are modeled after
653  * the __atomic interfaces but using the namespace ast_atomic.
654  *
655  * The memorder argument is always ignored by legacy __sync functions. Invalid
656  * memorder arguments do not produce errors unless __atomic functions are supported
657  * as the argument is erased by the preprocessor.
658  *
659  * \note ast_atomic_fetch_nand and ast_atomic_nand_fetch purposely do not exist.
660  * It's implementation was broken prior to gcc-4.4.
661  *
662  * @{
663  */
664 
665 #include "asterisk/inline_api.h"
666 
667 #if defined(HAVE_C_ATOMICS)
668 /*! Atomic += */
669 #define ast_atomic_fetch_add(ptr, val, memorder) __atomic_fetch_add((ptr), (val), (memorder))
670 #define ast_atomic_add_fetch(ptr, val, memorder) __atomic_add_fetch((ptr), (val), (memorder))
671 
672 /*! Atomic -= */
673 #define ast_atomic_fetch_sub(ptr, val, memorder) __atomic_fetch_sub((ptr), (val), (memorder))
674 #define ast_atomic_sub_fetch(ptr, val, memorder) __atomic_sub_fetch((ptr), (val), (memorder))
675 
676 /*! Atomic &= */
677 #define ast_atomic_fetch_and(ptr, val, memorder) __atomic_fetch_and((ptr), (val), (memorder))
678 #define ast_atomic_and_fetch(ptr, val, memorder) __atomic_and_fetch((ptr), (val), (memorder))
679 
680 /*! Atomic |= */
681 #define ast_atomic_fetch_or(ptr, val, memorder) __atomic_fetch_or((ptr), (val), (memorder))
682 #define ast_atomic_or_fetch(ptr, val, memorder) __atomic_or_fetch((ptr), (val), (memorder))
683 
684 /*! Atomic xor = */
685 #define ast_atomic_fetch_xor(ptr, val, memorder) __atomic_fetch_xor((ptr), (val), (memorder))
686 #define ast_atomic_xor_fetch(ptr, val, memorder) __atomic_xor_fetch((ptr), (val), (memorder))
687 
688 #if 0
689 /* Atomic compare and swap
690  *
691  * See comments near the __atomic implementation for why this is disabled.
692  */
693 #define ast_atomic_compare_exchange_n(ptr, expected, desired, success_memorder, failure_memorder) \
694  __atomic_compare_exchange_n((ptr), (expected), (desired), 0, success_memorder, failure_memorder)
695 
696 #define ast_atomic_compare_exchange(ptr, expected, desired, success_memorder, failure_memorder) \
697  __atomic_compare_exchange((ptr), (expected), (desired), 0, success_memorder, failure_memorder)
698 #endif
699 
700 #elif defined(HAVE_GCC_ATOMICS)
701 /*! Atomic += */
702 #define ast_atomic_fetch_add(ptr, val, memorder) __sync_fetch_and_add((ptr), (val))
703 #define ast_atomic_add_fetch(ptr, val, memorder) __sync_add_and_fetch((ptr), (val))
704 
705 /*! Atomic -= */
706 #define ast_atomic_fetch_sub(ptr, val, memorder) __sync_fetch_and_sub((ptr), (val))
707 #define ast_atomic_sub_fetch(ptr, val, memorder) __sync_sub_and_fetch((ptr), (val))
708 
709 /*! Atomic &= */
710 #define ast_atomic_fetch_and(ptr, val, memorder) __sync_fetch_and_and((ptr), (val))
711 #define ast_atomic_and_fetch(ptr, val, memorder) __sync_and_and_fetch((ptr), (val))
712 
713 /*! Atomic |= */
714 #define ast_atomic_fetch_or(ptr, val, memorder) __sync_fetch_and_or((ptr), (val))
715 #define ast_atomic_or_fetch(ptr, val, memorder) __sync_or_and_fetch((ptr), (val))
716 
717 /*! Atomic xor = */
718 #define ast_atomic_fetch_xor(ptr, val, memorder) __sync_fetch_and_xor((ptr), (val))
719 #define ast_atomic_xor_fetch(ptr, val, memorder) __sync_xor_and_fetch((ptr), (val))
720 
721 #if 0
722 /* Atomic compare and swap
723  *
724  * The \a expected argument is a pointer, I'm guessing __atomic built-ins
725  * perform all memory reads/writes in a single atomic operation. I don't
726  * believe this is possible to exactly replicate using __sync built-ins.
727  * Will need to determine potential use cases of this feature and write a
728  * wrapper which provides consistant behavior between __sync and __atomic
729  * implementations.
730  */
731 #define ast_atomic_compare_exchange_n(ptr, expected, desired, success_memorder, failure_memorder) \
732  __sync_bool_compare_and_swap((ptr), *(expected), (desired))
733 
734 #define ast_atomic_compare_exchange(ptr, expected, desired, success_memorder, failure_memorder) \
735  __sync_bool_compare_and_swap((ptr), *(expected), *(desired))
736 #endif
737 
738 #else
739 #error "Atomics not available."
740 #endif
741 
742 /*! Atomic flag set */
743 #define ast_atomic_flag_set(ptr, val, memorder) ast_atomic_fetch_or((ptr), (val), (memorder))
744 
745 /*! Atomic flag clear */
746 #define ast_atomic_flag_clear(ptr, val, memorder) ast_atomic_fetch_and((ptr), ~(val), (memorder))
747 
748 /*!
749  * \brief Atomically add v to *p and return the previous value of *p.
750  *
751  * This can be used to handle reference counts, and the return value
752  * can be used to generate unique identifiers.
753  */
754 AST_INLINE_API(int ast_atomic_fetchadd_int(volatile int *p, int v),
755 {
756  return ast_atomic_fetch_add(p, v, __ATOMIC_RELAXED);
757 })
758 
759 /*!
760  * \brief decrement *p by 1 and return true if the variable has reached 0.
761  *
762  * Useful e.g. to check if a refcount has reached 0.
763  */
764 AST_INLINE_API(int ast_atomic_dec_and_test(volatile int *p),
765 {
766  return ast_atomic_sub_fetch(p, 1, __ATOMIC_RELAXED) == 0;
767 })
768 
769 /*! @} */
770 
771 #endif /* _ASTERISK_LOCK_H */
struct ast_lock_track * _track
Definition: lock.h:165
Main Channel structure associated with a channel.
Asterisk backtrace generation.
Time-related functions and macros.
#define ast_atomic_fetch_add(ptr, val, memorder)
Support for atomic instructions.
Definition: lock.h:669
int ast_atomic_fetchadd_int(volatile int *p, int v)
Atomically add v to *p and return the previous value of *p.
Definition: lock.h:757
Compiler-specific macros and other items.
A structure to hold backtrace information. This structure provides an easy means to store backtrace i...
Definition: backtrace.h:50
Lock tracking information.
Definition: lock.h:111
volatile unsigned int setup
Definition: lock.h:127
Inlinable API function macro.
unsigned int tracking
Definition: lock.h:125
int ast_atomic_dec_and_test(volatile int *p)
decrement *p by 1 and return true if the variable has reached 0.
Definition: lock.h:767
Support for dynamic strings.
Definition: strings.h:623
Support for logging to various files, console and syslog Configuration in file logger.conf.
struct ast_lock_track * _track
Definition: lock.h:143
Structure for rwlock and tracking information.
Definition: lock.h:157
Structure for mutex and tracking information.
Definition: lock.h:135