lock.c

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/*
 * Asterisk -- An open source telephony toolkit.
 *
 * Copyright (C) 1999 - 2010, Digium, Inc.
 *
 * Mark Spencer <markster@digium.com>
 *
 * See http://www.asterisk.org for more information about
 * the Asterisk project. Please do not directly contact
 * any of the maintainers of this project for assistance;
 * the project provides a web site, mailing lists and IRC
 * channels for your use.
 *
 * This program is free software, distributed under the terms of
 * the GNU General Public License Version 2. See the LICENSE file
 * at the top of the source tree.
 */

/*! \file
 *
 * \brief General Asterisk locking.
 */

/*** MODULEINFO
   <support_level>core</support_level>
 ***/

#include "asterisk.h"

#ifdef HAVE_MTX_PROFILE
/* profile mutex */
static int mtx_prof = -1;
static void __attribute__((constructor)) __mtx_init(void)
{
   mtx_prof = ast_add_profile("mtx_lock_" __FILE__, 0);
}
#endif

#include "asterisk/utils.h"
#include "asterisk/lock.h"

/* Allow direct use of pthread_mutex_* / pthread_cond_* */
#undef pthread_mutex_init
#undef pthread_mutex_destroy
#undef pthread_mutex_lock
#undef pthread_mutex_trylock
#undef pthread_mutex_t
#undef pthread_mutex_unlock
#undef pthread_cond_init
#undef pthread_cond_signal
#undef pthread_cond_broadcast
#undef pthread_cond_destroy
#undef pthread_cond_wait
#undef pthread_cond_timedwait

#if defined(DEBUG_THREADS)
#define log_mutex_error(canlog, ...) \
   do { \
      if (canlog) { \
         ast_log(LOG_ERROR, __VA_ARGS__); \
      } else { \
         fprintf(stderr, __VA_ARGS__); \
      } \
   } while (0)
#endif

#if defined(DEBUG_THREADS) && defined(HAVE_BKTR)
static void __dump_backtrace(struct ast_bt *bt, int canlog)
{
   char **strings;
   ssize_t i;

   strings = backtrace_symbols(bt->addresses, bt->num_frames);

   for (i = 0; i < bt->num_frames; i++) {
      log_mutex_error(canlog, "%s\n", strings[i]);
   }

   ast_std_free(strings);
}
#endif   /* defined(DEBUG_THREADS) && defined(HAVE_BKTR) */

#ifdef DEBUG_THREADS
AST_MUTEX_DEFINE_STATIC(reentrancy_lock);

static inline struct ast_lock_track *ast_get_reentrancy(struct ast_lock_track **plt,
   struct ast_lock_track_flags *flags, int no_setup)
{
   pthread_mutexattr_t reentr_attr;
   struct ast_lock_track *lt;

   if (!flags->tracking || flags->setup) {
      return *plt;
   }

   pthread_mutex_lock(&reentrancy_lock.mutex);

   if (*plt) {
      pthread_mutex_unlock(&reentrancy_lock.mutex);
      return *plt;
   }

   if (no_setup) {
      pthread_mutex_unlock(&reentrancy_lock.mutex);
      return NULL;
   }

   lt = *plt = ast_std_calloc(1, sizeof(*lt));
   if (!lt) {
      fprintf(stderr, "%s: Failed to allocate lock tracking\n", __func__);
#if defined(DO_CRASH) || defined(THREAD_CRASH)
      abort();
#else
      pthread_mutex_unlock(&reentrancy_lock.mutex);
      return NULL;
#endif
   }

   pthread_mutexattr_init(&reentr_attr);
   pthread_mutexattr_settype(&reentr_attr, AST_MUTEX_KIND);
   pthread_mutex_init(&lt->reentr_mutex, &reentr_attr);
   pthread_mutexattr_destroy(&reentr_attr);

   flags->setup = 1;
   pthread_mutex_unlock(&reentrancy_lock.mutex);
   return lt;
}

static inline void delete_reentrancy_cs(struct ast_lock_track **plt)
{
   struct ast_lock_track *lt;

   if (*plt) {
      lt = *plt;
      *plt = NULL;

      pthread_mutex_destroy(&lt->reentr_mutex);
      ast_std_free(lt);
   }
}

#endif /* DEBUG_THREADS */

int __ast_pthread_mutex_init(int tracking, const char *filename, int lineno, const char *func,
                  const char *mutex_name, ast_mutex_t *t)
{
   int res;
   pthread_mutexattr_t  attr;

#ifdef DEBUG_THREADS
#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
   if ((t->mutex) != ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
      int canlog = tracking && strcmp(filename, "logger.c");

      log_mutex_error(canlog, "%s line %d (%s): NOTICE: mutex '%s' is already initialized.\n",
               filename, lineno, func, mutex_name);
      DO_THREAD_CRASH;
      return EBUSY;
   }
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */

   t->track = NULL;
   t->flags.tracking = tracking;
   t->flags.setup = 0;
#endif /* DEBUG_THREADS */

   pthread_mutexattr_init(&attr);
   pthread_mutexattr_settype(&attr, AST_MUTEX_KIND);
   res = pthread_mutex_init(&t->mutex, &attr);
   pthread_mutexattr_destroy(&attr);

   return res;
}

int __ast_pthread_mutex_destroy(const char *filename, int lineno, const char *func,
                  const char *mutex_name, ast_mutex_t *t)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 1);
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");

#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
   if ((t->mutex) == ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
      /* Don't try to uninitialize an uninitialized mutex
       * This may have no effect on linux
       * but it always generates a core on *BSD when
       * linked with libpthread.
       * This is not an error condition if the mutex is created on the fly.
       */
      log_mutex_error(canlog, "%s line %d (%s): NOTICE: mutex '%s' is uninitialized.\n",
               filename, lineno, func, mutex_name);
      DO_THREAD_CRASH;
      res = EINVAL;
      goto lt_cleanup;
   }
#endif

   res = pthread_mutex_trylock(&t->mutex);
   switch (res) {
   case 0:
      pthread_mutex_unlock(&t->mutex);
      break;
   case EINVAL:
      log_mutex_error(canlog, "%s line %d (%s): Error: attempt to destroy invalid mutex '%s'.\n",
              filename, lineno, func, mutex_name);
      break;
   case EBUSY:
      log_mutex_error(canlog, "%s line %d (%s): Error: attempt to destroy locked mutex '%s'.\n",
               filename, lineno, func, mutex_name);
      if (lt) {
         ast_reentrancy_lock(lt);
         log_mutex_error(canlog, "%s line %d (%s): Error: '%s' was locked here.\n",
                lt->file[ROFFSET], lt->lineno[ROFFSET], lt->func[ROFFSET], mutex_name);
#ifdef HAVE_BKTR
         __dump_backtrace(&lt->backtrace[ROFFSET], canlog);
#endif
         ast_reentrancy_unlock(lt);
      }
      break;
   }
#endif /* DEBUG_THREADS */

   res = pthread_mutex_destroy(&t->mutex);

#ifdef DEBUG_THREADS
   if (res) {
      log_mutex_error(canlog, "%s line %d (%s): Error destroying mutex %s: %s\n",
               filename, lineno, func, mutex_name, strerror(res));
   }
#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
lt_cleanup:
#endif
   if (lt) {
      ast_reentrancy_lock(lt);
      lt->file[0] = filename;
      lt->lineno[0] = lineno;
      lt->func[0] = func;
      lt->reentrancy = 0;
      lt->thread_id[0] = 0;
#ifdef HAVE_BKTR
      memset(&lt->backtrace[0], 0, sizeof(lt->backtrace[0]));
#endif
      ast_reentrancy_unlock(lt);
      delete_reentrancy_cs(&t->track);
   }
#endif /* DEBUG_THREADS */

   return res;
}

int __ast_pthread_mutex_lock(const char *filename, int lineno, const char *func,
            const char* mutex_name, ast_mutex_t *t)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");
   struct ast_bt *bt = NULL;

   if (lt) {
#ifdef HAVE_BKTR
      struct ast_bt tmp;

      /* The implementation of backtrace() may have its own locks.
       * Capture the backtrace outside of the reentrancy lock to
       * avoid deadlocks. See ASTERISK-22455. */
      ast_bt_get_addresses(&tmp);

      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->backtrace[lt->reentrancy] = tmp;
         bt = &lt->backtrace[lt->reentrancy];
      }
      ast_reentrancy_unlock(lt);
#endif
      ast_store_lock_info(AST_MUTEX, filename, lineno, func, mutex_name, t, bt);
   }
#endif /* DEBUG_THREADS */

#if defined(DETECT_DEADLOCKS) && defined(DEBUG_THREADS)
   {
      time_t seconds = time(NULL);
      time_t wait_time, reported_wait = 0;
      do {
#ifdef   HAVE_MTX_PROFILE
         ast_mark(mtx_prof, 1);
#endif
         res = pthread_mutex_trylock(&t->mutex);
#ifdef   HAVE_MTX_PROFILE
         ast_mark(mtx_prof, 0);
#endif
         if (res == EBUSY) {
            wait_time = time(NULL) - seconds;
            if (wait_time > reported_wait && (wait_time % 5) == 0) {
               log_mutex_error(canlog, "%s line %d (%s): Deadlock? waited %d sec for mutex '%s'?\n",
                        filename, lineno, func, (int) wait_time, mutex_name);
               if (lt) {
                  ast_reentrancy_lock(lt);
#ifdef HAVE_BKTR
                  __dump_backtrace(&lt->backtrace[lt->reentrancy], canlog);
#endif
                  log_mutex_error(canlog, "%s line %d (%s): '%s' was locked here.\n",
                           lt->file[ROFFSET], lt->lineno[ROFFSET],
                           lt->func[ROFFSET], mutex_name);
#ifdef HAVE_BKTR
                  __dump_backtrace(&lt->backtrace[ROFFSET], canlog);
#endif
                  ast_reentrancy_unlock(lt);
               }
               reported_wait = wait_time;
            }
            usleep(200);
         }
      } while (res == EBUSY);
   }
#else /* !DETECT_DEADLOCKS || !DEBUG_THREADS */
#ifdef   HAVE_MTX_PROFILE
   ast_mark(mtx_prof, 1);
   res = pthread_mutex_trylock(&t->mutex);
   ast_mark(mtx_prof, 0);
   if (res)
#endif
   res = pthread_mutex_lock(&t->mutex);
#endif /* !DETECT_DEADLOCKS || !DEBUG_THREADS */

#ifdef DEBUG_THREADS
   if (lt && !res) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->file[lt->reentrancy] = filename;
         lt->lineno[lt->reentrancy] = lineno;
         lt->func[lt->reentrancy] = func;
         lt->thread_id[lt->reentrancy] = pthread_self();
         lt->reentrancy++;
      } else {
         log_mutex_error(canlog, "%s line %d (%s): '%s' really deep reentrancy!\n",
                        filename, lineno, func, mutex_name);
      }
      ast_reentrancy_unlock(lt);
      ast_mark_lock_acquired(t);
   } else if (lt) {
#ifdef HAVE_BKTR
      if (lt->reentrancy) {
         ast_reentrancy_lock(lt);
         bt = &lt->backtrace[lt->reentrancy-1];
         ast_reentrancy_unlock(lt);
      } else {
         bt = NULL;
      }
#endif
      ast_remove_lock_info(t, bt);
   }
   if (res) {
      log_mutex_error(canlog, "%s line %d (%s): Error obtaining mutex: %s\n",
               filename, lineno, func, strerror(res));
      DO_THREAD_CRASH;
   }
#endif /* DEBUG_THREADS */

   return res;
}

int __ast_pthread_mutex_trylock(const char *filename, int lineno, const char *func,
            const char* mutex_name, ast_mutex_t *t)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");
   struct ast_bt *bt = NULL;

   if (lt) {
#ifdef HAVE_BKTR
      struct ast_bt tmp;

      /* The implementation of backtrace() may have its own locks.
       * Capture the backtrace outside of the reentrancy lock to
       * avoid deadlocks. See ASTERISK-22455. */
      ast_bt_get_addresses(&tmp);

      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->backtrace[lt->reentrancy] = tmp;
         bt = &lt->backtrace[lt->reentrancy];
      }
      ast_reentrancy_unlock(lt);
#endif
      ast_store_lock_info(AST_MUTEX, filename, lineno, func, mutex_name, t, bt);
   }
#endif /* DEBUG_THREADS */

   res = pthread_mutex_trylock(&t->mutex);

#ifdef DEBUG_THREADS
   if (lt && !res) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->file[lt->reentrancy] = filename;
         lt->lineno[lt->reentrancy] = lineno;
         lt->func[lt->reentrancy] = func;
         lt->thread_id[lt->reentrancy] = pthread_self();
         lt->reentrancy++;
      } else {
         log_mutex_error(canlog, "%s line %d (%s): '%s' really deep reentrancy!\n",
                  filename, lineno, func, mutex_name);
      }
      ast_reentrancy_unlock(lt);
      ast_mark_lock_acquired(t);
   } else if (lt) {
      ast_mark_lock_failed(t);
   }
#endif /* DEBUG_THREADS */

   return res;
}

int __ast_pthread_mutex_unlock(const char *filename, int lineno, const char *func,
                    const char *mutex_name, ast_mutex_t *t)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = NULL;
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");
   struct ast_bt *bt = NULL;

#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
   if ((t->mutex) == ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
      log_mutex_error(canlog, "%s line %d (%s): Error: mutex '%s' is uninitialized.\n",
               filename, lineno, func, mutex_name);
      DO_THREAD_CRASH;
      return EINVAL;
   }
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */

   lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   if (lt) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy && (lt->thread_id[ROFFSET] != pthread_self())) {
         log_mutex_error(canlog, "%s line %d (%s): attempted unlock mutex '%s' without owning it!\n",
                  filename, lineno, func, mutex_name);
         log_mutex_error(canlog, "%s line %d (%s): '%s' was locked here.\n",
                  lt->file[ROFFSET], lt->lineno[ROFFSET], lt->func[ROFFSET], mutex_name);
#ifdef HAVE_BKTR
         __dump_backtrace(&lt->backtrace[ROFFSET], canlog);
#endif
         DO_THREAD_CRASH;
      }

      if (--lt->reentrancy < 0) {
         log_mutex_error(canlog, "%s line %d (%s): mutex '%s' freed more times than we've locked!\n",
                  filename, lineno, func, mutex_name);
         lt->reentrancy = 0;
      }

      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->file[lt->reentrancy] = NULL;
         lt->lineno[lt->reentrancy] = 0;
         lt->func[lt->reentrancy] = NULL;
         lt->thread_id[lt->reentrancy] = 0;
      }

#ifdef HAVE_BKTR
      if (lt->reentrancy) {
         bt = &lt->backtrace[lt->reentrancy - 1];
      }
#endif
      ast_reentrancy_unlock(lt);

      ast_remove_lock_info(t, bt);
   }
#endif /* DEBUG_THREADS */

   res = pthread_mutex_unlock(&t->mutex);

#ifdef DEBUG_THREADS
   if (res) {
      log_mutex_error(canlog, "%s line %d (%s): Error releasing mutex: %s\n",
               filename, lineno, func, strerror(res));
      DO_THREAD_CRASH;
   }
#endif /* DEBUG_THREADS */

   return res;
}


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)
{
   return pthread_cond_init(cond, cond_attr);
}

int __ast_cond_signal(const char *filename, int lineno, const char *func,
                const char *cond_name, ast_cond_t *cond)
{
   return pthread_cond_signal(cond);
}

int __ast_cond_broadcast(const char *filename, int lineno, const char *func,
                   const char *cond_name, ast_cond_t *cond)
{
   return pthread_cond_broadcast(cond);
}

int __ast_cond_destroy(const char *filename, int lineno, const char *func,
                 const char *cond_name, ast_cond_t *cond)
{
   return pthread_cond_destroy(cond);
}

#ifdef DEBUG_THREADS
static void restore_lock_tracking(struct ast_lock_track *lt, struct ast_lock_track *lt_saved)
{
   ast_reentrancy_lock(lt);

   /*
    * The following code must match the struct ast_lock_track
    * definition with the explicit exception of the reentr_mutex
    * member.
    */
   memcpy(lt->file, lt_saved->file, sizeof(lt->file));
   memcpy(lt->lineno, lt_saved->lineno, sizeof(lt->lineno));
   lt->reentrancy = lt_saved->reentrancy;
   memcpy(lt->func, lt_saved->func, sizeof(lt->func));
   memcpy(lt->thread_id, lt_saved->thread_id, sizeof(lt->thread_id));
#ifdef HAVE_BKTR
   memcpy(lt->backtrace, lt_saved->backtrace, sizeof(lt->backtrace));
#endif

   ast_reentrancy_unlock(lt);
}
#endif /* DEBUG_THREADS */

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)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = NULL;
   struct ast_lock_track lt_orig;
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");

#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
   if ((t->mutex) == ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
      log_mutex_error(canlog, "%s line %d (%s): Error: mutex '%s' is uninitialized.\n",
               filename, lineno, func, mutex_name);
      DO_THREAD_CRASH;
      return EINVAL;
   }
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */

   lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   if (lt) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy && (lt->thread_id[ROFFSET] != pthread_self())) {
         log_mutex_error(canlog, "%s line %d (%s): attempted wait using mutex '%s' without owning it!\n",
                  filename, lineno, func, mutex_name);
         log_mutex_error(canlog, "%s line %d (%s): '%s' was locked here.\n",
                  lt->file[ROFFSET], lt->lineno[ROFFSET], lt->func[ROFFSET], mutex_name);
#ifdef HAVE_BKTR
         __dump_backtrace(&lt->backtrace[ROFFSET], canlog);
#endif
         DO_THREAD_CRASH;
      } else if (lt->reentrancy <= 0) {
         log_mutex_error(canlog, "%s line %d (%s): attempted wait using an unlocked mutex '%s'\n",
                  filename, lineno, func, mutex_name);
         DO_THREAD_CRASH;
      }

      /* Waiting on a condition completely suspends a recursive mutex,
       * even if it's been recursively locked multiple times. Make a
       * copy of the lock tracking, and reset reentrancy to zero */
      lt_orig = *lt;
      lt->reentrancy = 0;
      ast_reentrancy_unlock(lt);

      ast_suspend_lock_info(t);
   }
#endif /* DEBUG_THREADS */

   res = pthread_cond_wait(cond, &t->mutex);

#ifdef DEBUG_THREADS
   if (res) {
      log_mutex_error(canlog, "%s line %d (%s): Error waiting on condition mutex '%s'\n",
               filename, lineno, func, strerror(res));
      DO_THREAD_CRASH;
   } else if (lt) {
      restore_lock_tracking(lt, &lt_orig);
      ast_restore_lock_info(t);
   }
#endif /* DEBUG_THREADS */

   return res;
}

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)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = NULL;
   struct ast_lock_track lt_orig;
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");

#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
   if ((t->mutex) == ((pthread_mutex_t) PTHREAD_MUTEX_INITIALIZER)) {
      log_mutex_error(canlog, "%s line %d (%s): Error: mutex '%s' is uninitialized.\n",
               filename, lineno, func, mutex_name);
      DO_THREAD_CRASH;
      return EINVAL;
   }
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */

   lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   if (lt) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy && (lt->thread_id[ROFFSET] != pthread_self())) {
         log_mutex_error(canlog, "%s line %d (%s): attempted wait using mutex '%s' without owning it!\n",
                  filename, lineno, func, mutex_name);
         log_mutex_error(canlog, "%s line %d (%s): '%s' was locked here.\n",
                  lt->file[ROFFSET], lt->lineno[ROFFSET], lt->func[ROFFSET], mutex_name);
#ifdef HAVE_BKTR
         __dump_backtrace(&lt->backtrace[ROFFSET], canlog);
#endif
         DO_THREAD_CRASH;
      } else if (lt->reentrancy <= 0) {
         log_mutex_error(canlog, "%s line %d (%s): attempted wait using an unlocked mutex '%s'\n",
                  filename, lineno, func, mutex_name);
         DO_THREAD_CRASH;
      }

      /* Waiting on a condition completely suspends a recursive mutex,
       * even if it's been recursively locked multiple times. Make a
       * copy of the lock tracking, and reset reentrancy to zero */
      lt_orig = *lt;
      lt->reentrancy = 0;
      ast_reentrancy_unlock(lt);

      ast_suspend_lock_info(t);
   }
#endif /* DEBUG_THREADS */

   res = pthread_cond_timedwait(cond, &t->mutex, abstime);

#ifdef DEBUG_THREADS
   if (res && (res != ETIMEDOUT)) {
      log_mutex_error(canlog, "%s line %d (%s): Error waiting on condition mutex '%s'\n",
               filename, lineno, func, strerror(res));
      DO_THREAD_CRASH;
   } else if (lt) {
      restore_lock_tracking(lt, &lt_orig);
      ast_restore_lock_info(t);
   }
#endif /* DEBUG_THREADS */

   return res;
}

int __ast_rwlock_init(int tracking, const char *filename, int lineno, const char *func, const char *rwlock_name, ast_rwlock_t *t)
{
   int res;
   pthread_rwlockattr_t attr;

#ifdef DEBUG_THREADS
#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
   if (t->lock != ((pthread_rwlock_t) __AST_RWLOCK_INIT_VALUE)) {
      int canlog = tracking && strcmp(filename, "logger.c");

      log_mutex_error(canlog, "%s line %d (%s): Warning: rwlock '%s' is already initialized.\n",
            filename, lineno, func, rwlock_name);
      DO_THREAD_CRASH;
      return EBUSY;
   }
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */

   t->track = NULL;
   t->flags.tracking = tracking;
   t->flags.setup = 0;
#endif /* DEBUG_THREADS */

   pthread_rwlockattr_init(&attr);
#ifdef HAVE_PTHREAD_RWLOCK_PREFER_WRITER_NP
   pthread_rwlockattr_setkind_np(&attr, PTHREAD_RWLOCK_PREFER_WRITER_NP);
#endif
   res = pthread_rwlock_init(&t->lock, &attr);
   pthread_rwlockattr_destroy(&attr);

   return res;
}

int __ast_rwlock_destroy(const char *filename, int lineno, const char *func, const char *rwlock_name, ast_rwlock_t *t)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 1);
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");

#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
   if (t->lock == ((pthread_rwlock_t) __AST_RWLOCK_INIT_VALUE)) {
      log_mutex_error(canlog, "%s line %d (%s): Warning: rwlock '%s' is uninitialized.\n",
               filename, lineno, func, rwlock_name);
      DO_THREAD_CRASH;
      res = EINVAL;
      goto lt_cleanup;
   }
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
#endif /* DEBUG_THREADS */

   res = pthread_rwlock_destroy(&t->lock);

#ifdef DEBUG_THREADS
   if (res) {
      log_mutex_error(canlog, "%s line %d (%s): Error destroying rwlock %s: %s\n",
            filename, lineno, func, rwlock_name, strerror(res));
   }
#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
lt_cleanup:
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */
   if (lt) {
      ast_reentrancy_lock(lt);
      lt->file[0] = filename;
      lt->lineno[0] = lineno;
      lt->func[0] = func;
      lt->reentrancy = 0;
      lt->thread_id[0] = 0;
#ifdef HAVE_BKTR
      memset(&lt->backtrace[0], 0, sizeof(lt->backtrace[0]));
#endif
      ast_reentrancy_unlock(lt);
      delete_reentrancy_cs(&t->track);
   }
#endif /* DEBUG_THREADS */

   return res;
}

int __ast_rwlock_unlock(const char *filename, int line, const char *func, ast_rwlock_t *t, const char *name)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = NULL;
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");
   struct ast_bt *bt = NULL;
   int lock_found = 0;

#if defined(AST_MUTEX_INIT_W_CONSTRUCTORS) && defined(CAN_COMPARE_MUTEX_TO_INIT_VALUE)
   if ((t->lock) == ((pthread_rwlock_t) __AST_RWLOCK_INIT_VALUE)) {
      log_mutex_error(canlog, "%s line %d (%s): Warning: rwlock '%s' is uninitialized.\n",
               filename, line, func, name);
      DO_THREAD_CRASH;
      return EINVAL;
   }
#endif /* AST_MUTEX_INIT_W_CONSTRUCTORS */

   lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   if (lt) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy) {
         int i;
         pthread_t self = pthread_self();
         for (i = lt->reentrancy - 1; i >= 0; --i) {
            if (lt->thread_id[i] == self) {
               lock_found = 1;
               if (i != lt->reentrancy - 1) {
                  lt->file[i] = lt->file[lt->reentrancy - 1];
                  lt->lineno[i] = lt->lineno[lt->reentrancy - 1];
                  lt->func[i] = lt->func[lt->reentrancy - 1];
                  lt->thread_id[i] = lt->thread_id[lt->reentrancy - 1];
               }
#ifdef HAVE_BKTR
               bt = &lt->backtrace[i];
#endif
               lt->file[lt->reentrancy - 1] = NULL;
               lt->lineno[lt->reentrancy - 1] = 0;
               lt->func[lt->reentrancy - 1] = NULL;
               lt->thread_id[lt->reentrancy - 1] = AST_PTHREADT_NULL;
               break;
            }
         }
      }

      if (lock_found && --lt->reentrancy < 0) {
         log_mutex_error(canlog, "%s line %d (%s): rwlock '%s' freed more times than we've locked!\n",
               filename, line, func, name);
         lt->reentrancy = 0;
      }

      ast_reentrancy_unlock(lt);

      ast_remove_lock_info(t, bt);
   }
#endif /* DEBUG_THREADS */

   res = pthread_rwlock_unlock(&t->lock);

#ifdef DEBUG_THREADS
   if (res) {
      log_mutex_error(canlog, "%s line %d (%s): Error releasing rwlock: %s\n",
            filename, line, func, strerror(res));
      DO_THREAD_CRASH;
   }
#endif /* DEBUG_THREADS */

   return res;
}

int __ast_rwlock_rdlock(const char *filename, int line, const char *func, ast_rwlock_t *t, const char *name)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");
   struct ast_bt *bt = NULL;

   if (lt) {
#ifdef HAVE_BKTR
      struct ast_bt tmp;

      /* The implementation of backtrace() may have its own locks.
       * Capture the backtrace outside of the reentrancy lock to
       * avoid deadlocks. See ASTERISK-22455. */
      ast_bt_get_addresses(&tmp);

      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->backtrace[lt->reentrancy] = tmp;
         bt = &lt->backtrace[lt->reentrancy];
      }
      ast_reentrancy_unlock(lt);
#endif
      ast_store_lock_info(AST_RDLOCK, filename, line, func, name, t, bt);
   }
#endif /* DEBUG_THREADS */

#if defined(DETECT_DEADLOCKS) && defined(DEBUG_THREADS)
   {
      time_t seconds = time(NULL);
      time_t wait_time, reported_wait = 0;
      do {
         res = pthread_rwlock_tryrdlock(&t->lock);
         if (res == EBUSY) {
            wait_time = time(NULL) - seconds;
            if (wait_time > reported_wait && (wait_time % 5) == 0) {
               log_mutex_error(canlog, "%s line %d (%s): Deadlock? waited %d sec for readlock '%s'?\n",
                  filename, line, func, (int)wait_time, name);
               if (lt) {
                  ast_reentrancy_lock(lt);
#ifdef HAVE_BKTR
                  __dump_backtrace(&lt->backtrace[lt->reentrancy], canlog);
#endif
                  log_mutex_error(canlog, "%s line %d (%s): '%s' was locked  here.\n",
                        lt->file[lt->reentrancy-1], lt->lineno[lt->reentrancy-1],
                        lt->func[lt->reentrancy-1], name);
#ifdef HAVE_BKTR
                  __dump_backtrace(&lt->backtrace[lt->reentrancy-1], canlog);
#endif
                  ast_reentrancy_unlock(lt);
               }
               reported_wait = wait_time;
            }
            usleep(200);
         }
      } while (res == EBUSY);
   }
#else /* !DETECT_DEADLOCKS || !DEBUG_THREADS */
   res = pthread_rwlock_rdlock(&t->lock);
#endif /* !DETECT_DEADLOCKS || !DEBUG_THREADS */

#ifdef DEBUG_THREADS
   if (!res && lt) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->file[lt->reentrancy] = filename;
         lt->lineno[lt->reentrancy] = line;
         lt->func[lt->reentrancy] = func;
         lt->thread_id[lt->reentrancy] = pthread_self();
         lt->reentrancy++;
      }
      ast_reentrancy_unlock(lt);
      ast_mark_lock_acquired(t);
   } else if (lt) {
#ifdef HAVE_BKTR
      if (lt->reentrancy) {
         ast_reentrancy_lock(lt);
         bt = &lt->backtrace[lt->reentrancy-1];
         ast_reentrancy_unlock(lt);
      } else {
         bt = NULL;
      }
#endif
      ast_remove_lock_info(t, bt);
   }

   if (res) {
      log_mutex_error(canlog, "%s line %d (%s): Error obtaining read lock: %s\n",
            filename, line, func, strerror(res));
      DO_THREAD_CRASH;
   }
#endif /* DEBUG_THREADS */

   return res;
}

int __ast_rwlock_wrlock(const char *filename, int line, const char *func, ast_rwlock_t *t, const char *name)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");
   struct ast_bt *bt = NULL;

   if (lt) {
#ifdef HAVE_BKTR
      struct ast_bt tmp;

      /* The implementation of backtrace() may have its own locks.
       * Capture the backtrace outside of the reentrancy lock to
       * avoid deadlocks. See ASTERISK-22455. */
      ast_bt_get_addresses(&tmp);

      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->backtrace[lt->reentrancy] = tmp;
         bt = &lt->backtrace[lt->reentrancy];
      }
      ast_reentrancy_unlock(lt);
#endif
      ast_store_lock_info(AST_WRLOCK, filename, line, func, name, t, bt);
   }
#endif /* DEBUG_THREADS */

#if defined(DETECT_DEADLOCKS) && defined(DEBUG_THREADS)
   {
      time_t seconds = time(NULL);
      time_t wait_time, reported_wait = 0;
      do {
         res = pthread_rwlock_trywrlock(&t->lock);
         if (res == EBUSY) {
            wait_time = time(NULL) - seconds;
            if (wait_time > reported_wait && (wait_time % 5) == 0) {
               log_mutex_error(canlog, "%s line %d (%s): Deadlock? waited %d sec for writelock '%s'?\n",
                  filename, line, func, (int)wait_time, name);
               if (lt) {
                  ast_reentrancy_lock(lt);
#ifdef HAVE_BKTR
                  __dump_backtrace(&lt->backtrace[lt->reentrancy], canlog);
#endif
                  log_mutex_error(canlog, "%s line %d (%s): '%s' was locked  here.\n",
                        lt->file[lt->reentrancy-1], lt->lineno[lt->reentrancy-1],
                        lt->func[lt->reentrancy-1], name);
#ifdef HAVE_BKTR
                  __dump_backtrace(&lt->backtrace[lt->reentrancy-1], canlog);
#endif
                  ast_reentrancy_unlock(lt);
               }
               reported_wait = wait_time;
            }
            usleep(200);
         }
      } while (res == EBUSY);
   }
#else /* !DETECT_DEADLOCKS || !DEBUG_THREADS */
   res = pthread_rwlock_wrlock(&t->lock);
#endif /* !DETECT_DEADLOCKS || !DEBUG_THREADS */

#ifdef DEBUG_THREADS
   if (!res && lt) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->file[lt->reentrancy] = filename;
         lt->lineno[lt->reentrancy] = line;
         lt->func[lt->reentrancy] = func;
         lt->thread_id[lt->reentrancy] = pthread_self();
         lt->reentrancy++;
      }
      ast_reentrancy_unlock(lt);
      ast_mark_lock_acquired(t);
   } else if (lt) {
#ifdef HAVE_BKTR
      if (lt->reentrancy) {
         ast_reentrancy_lock(lt);
         bt = &lt->backtrace[lt->reentrancy-1];
         ast_reentrancy_unlock(lt);
      } else {
         bt = NULL;
      }
#endif
      ast_remove_lock_info(t, bt);
   }
   if (res) {
      log_mutex_error(canlog, "%s line %d (%s): Error obtaining write lock: %s\n",
            filename, line, func, strerror(res));
      DO_THREAD_CRASH;
   }
#endif /* DEBUG_THREADS */

   return res;
}

int __ast_rwlock_timedrdlock(const char *filename, int line, const char *func, ast_rwlock_t *t, const char *name,
   const struct timespec *abs_timeout)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");
   struct ast_bt *bt = NULL;

   if (lt) {
#ifdef HAVE_BKTR
      struct ast_bt tmp;

      /* The implementation of backtrace() may have its own locks.
       * Capture the backtrace outside of the reentrancy lock to
       * avoid deadlocks. See ASTERISK-22455. */
      ast_bt_get_addresses(&tmp);

      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->backtrace[lt->reentrancy] = tmp;
         bt = &lt->backtrace[lt->reentrancy];
      }
      ast_reentrancy_unlock(lt);
#endif
      ast_store_lock_info(AST_WRLOCK, filename, line, func, name, t, bt);
   }
#endif /* DEBUG_THREADS */

#ifdef HAVE_PTHREAD_RWLOCK_TIMEDWRLOCK
   res = pthread_rwlock_timedrdlock(&t->lock, abs_timeout);
#else
   do {
      struct timeval _now;
      for (;;) {
         if (!(res = pthread_rwlock_tryrdlock(&t->lock))) {
            break;
         }
         _now = ast_tvnow();
         if (_now.tv_sec > abs_timeout->tv_sec || (_now.tv_sec == abs_timeout->tv_sec && _now.tv_usec * 1000 > abs_timeout->tv_nsec)) {
            break;
         }
         usleep(1);
      }
   } while (0);
#endif

#ifdef DEBUG_THREADS
   if (!res && lt) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->file[lt->reentrancy] = filename;
         lt->lineno[lt->reentrancy] = line;
         lt->func[lt->reentrancy] = func;
         lt->thread_id[lt->reentrancy] = pthread_self();
         lt->reentrancy++;
      }
      ast_reentrancy_unlock(lt);
      ast_mark_lock_acquired(t);
   } else if (lt) {
#ifdef HAVE_BKTR
      if (lt->reentrancy) {
         ast_reentrancy_lock(lt);
         bt = &lt->backtrace[lt->reentrancy-1];
         ast_reentrancy_unlock(lt);
      } else {
         bt = NULL;
      }
#endif
      ast_remove_lock_info(t, bt);
   }
   if (res) {
      log_mutex_error(canlog, "%s line %d (%s): Error obtaining read lock: %s\n",
            filename, line, func, strerror(res));
      DO_THREAD_CRASH;
   }
#endif /* DEBUG_THREADS */

   return res;
}

int __ast_rwlock_timedwrlock(const char *filename, int line, const char *func, ast_rwlock_t *t, const char *name,
   const struct timespec *abs_timeout)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   int canlog = t->flags.tracking && strcmp(filename, "logger.c");
   struct ast_bt *bt = NULL;

   if (lt) {
#ifdef HAVE_BKTR
      struct ast_bt tmp;

      /* The implementation of backtrace() may have its own locks.
       * Capture the backtrace outside of the reentrancy lock to
       * avoid deadlocks. See ASTERISK-22455. */
      ast_bt_get_addresses(&tmp);

      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->backtrace[lt->reentrancy] = tmp;
         bt = &lt->backtrace[lt->reentrancy];
      }
      ast_reentrancy_unlock(lt);
#endif
      ast_store_lock_info(AST_WRLOCK, filename, line, func, name, t, bt);
   }
#endif /* DEBUG_THREADS */

#ifdef HAVE_PTHREAD_RWLOCK_TIMEDWRLOCK
   res = pthread_rwlock_timedwrlock(&t->lock, abs_timeout);
#else
   do {
      struct timeval _now;
      for (;;) {
         if (!(res = pthread_rwlock_trywrlock(&t->lock))) {
            break;
         }
         _now = ast_tvnow();
         if (_now.tv_sec > abs_timeout->tv_sec || (_now.tv_sec == abs_timeout->tv_sec && _now.tv_usec * 1000 > abs_timeout->tv_nsec)) {
            break;
         }
         usleep(1);
      }
   } while (0);
#endif

#ifdef DEBUG_THREADS
   if (!res && lt) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->file[lt->reentrancy] = filename;
         lt->lineno[lt->reentrancy] = line;
         lt->func[lt->reentrancy] = func;
         lt->thread_id[lt->reentrancy] = pthread_self();
         lt->reentrancy++;
      }
      ast_reentrancy_unlock(lt);
      ast_mark_lock_acquired(t);
   } else if (lt) {
#ifdef HAVE_BKTR
      if (lt->reentrancy) {
         ast_reentrancy_lock(lt);
         bt = &lt->backtrace[lt->reentrancy-1];
         ast_reentrancy_unlock(lt);
      } else {
         bt = NULL;
      }
#endif
      ast_remove_lock_info(t, bt);
   }
   if (res) {
      log_mutex_error(canlog, "%s line %d (%s): Error obtaining read lock: %s\n",
            filename, line, func, strerror(res));
      DO_THREAD_CRASH;
   }
#endif /* DEBUG_THREADS */

   return res;
}

int __ast_rwlock_tryrdlock(const char *filename, int line, const char *func, ast_rwlock_t *t, const char *name)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   struct ast_bt *bt = NULL;

   if (lt) {
#ifdef HAVE_BKTR
      struct ast_bt tmp;

      /* The implementation of backtrace() may have its own locks.
       * Capture the backtrace outside of the reentrancy lock to
       * avoid deadlocks. See ASTERISK-22455. */
      ast_bt_get_addresses(&tmp);

      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->backtrace[lt->reentrancy] = tmp;
         bt = &lt->backtrace[lt->reentrancy];
      }
      ast_reentrancy_unlock(lt);
#endif
      ast_store_lock_info(AST_RDLOCK, filename, line, func, name, t, bt);
   }
#endif /* DEBUG_THREADS */

   res = pthread_rwlock_tryrdlock(&t->lock);

#ifdef DEBUG_THREADS
   if (!res && lt) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->file[lt->reentrancy] = filename;
         lt->lineno[lt->reentrancy] = line;
         lt->func[lt->reentrancy] = func;
         lt->thread_id[lt->reentrancy] = pthread_self();
         lt->reentrancy++;
      }
      ast_reentrancy_unlock(lt);
      ast_mark_lock_acquired(t);
   } else if (lt) {
      ast_mark_lock_failed(t);
   }
#endif /* DEBUG_THREADS */

   return res;
}

int __ast_rwlock_trywrlock(const char *filename, int line, const char *func, ast_rwlock_t *t, const char *name)
{
   int res;

#ifdef DEBUG_THREADS
   struct ast_lock_track *lt = ast_get_reentrancy(&t->track, &t->flags, 0);
   struct ast_bt *bt = NULL;

   if (lt) {
#ifdef HAVE_BKTR
      struct ast_bt tmp;

      /* The implementation of backtrace() may have its own locks.
       * Capture the backtrace outside of the reentrancy lock to
       * avoid deadlocks. See ASTERISK-22455. */
      ast_bt_get_addresses(&tmp);

      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->backtrace[lt->reentrancy] = tmp;
         bt = &lt->backtrace[lt->reentrancy];
      }
      ast_reentrancy_unlock(lt);
#endif
      ast_store_lock_info(AST_WRLOCK, filename, line, func, name, t, bt);
   }
#endif /* DEBUG_THREADS */

   res = pthread_rwlock_trywrlock(&t->lock);

#ifdef DEBUG_THREADS
   if (!res && lt) {
      ast_reentrancy_lock(lt);
      if (lt->reentrancy < AST_MAX_REENTRANCY) {
         lt->file[lt->reentrancy] = filename;
         lt->lineno[lt->reentrancy] = line;
         lt->func[lt->reentrancy] = func;
         lt->thread_id[lt->reentrancy] = pthread_self();
         lt->reentrancy++;
      }
      ast_reentrancy_unlock(lt);
      ast_mark_lock_acquired(t);
   } else if (lt) {
      ast_mark_lock_failed(t);
   }
#endif /* DEBUG_THREADS */

   return res;
}