nptl/pthread_cond_destroy.c

   1 /* Copyright (C) 2002, 2003, 2004, 2007 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <errno.h>
  21 #include <shlib-compat.h>
  22 #include "pthreadP.h"
  23
  24
  25 int
  26 __pthread_cond_destroy (cond)
  27      pthread_cond_t *cond;
  28 {
  29   /* Make sure we are alone.  */
  30   lll_mutex_lock (cond->__data.__lock);
  31
  32   if (cond->__data.__total_seq > cond->__data.__wakeup_seq)
  33     {
  34       /* If there are still some waiters which have not been
  35          woken up, this is an application bug.  */
  36       lll_mutex_unlock (cond->__data.__lock);
  37       return EBUSY;
  38     }
  39
  40   /* Tell pthread_cond_*wait that this condvar is being destroyed.  */
  41   cond->__data.__total_seq = -1ULL;
  42
  43   /* If there are waiters which have been already signalled or
  44      broadcasted, but still are using the pthread_cond_t structure,
  45      pthread_cond_destroy needs to wait for them.  */
  46   unsigned int nwaiters = cond->__data.__nwaiters;
  47
  48   if (nwaiters >= (1 << COND_NWAITERS_SHIFT))
  49     {
  50       /* Wake everybody on the associated mutex in case there are
  51          threads that have been requeued to it.
  52          Without this, pthread_cond_destroy could block potentially
  53          for a long time or forever, as it would depend on other
  54          thread's using the mutex.
  55          When all threads waiting on the mutex are woken up, pthread_cond_wait
  56          only waits for threads to acquire and release the internal
  57          condvar lock.  */
  58       if (cond->__data.__mutex != NULL
  59           && cond->__data.__mutex != (void *) ~0l)
  60         {
  61           pthread_mutex_t *mut = (pthread_mutex_t *) cond->__data.__mutex;
  62           lll_futex_wake (&mut->__data.__lock, INT_MAX,
  63                           // XYZ check mutex flag
  64                           LLL_SHARED);
  65         }
  66
  67       do
  68         {
  69           lll_mutex_unlock (cond->__data.__lock);
  70
  71           lll_futex_wait (&cond->__data.__nwaiters, nwaiters,
  72                           // XYZ check mutex flag
  73                           LLL_SHARED);
  74
  75           lll_mutex_lock (cond->__data.__lock);
  76
  77           nwaiters = cond->__data.__nwaiters;
  78         }
  79       while (nwaiters >= (1 << COND_NWAITERS_SHIFT));
  80     }
  81
  82   return 0;
  83 }
  84 versioned_symbol (libpthread, __pthread_cond_destroy,
  85                   pthread_cond_destroy, GLIBC_2_3_2);