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   int pshared = (cond->__data.__mutex == (void *) ~0l)
  30                 ? LLL_SHARED : LLL_PRIVATE;
  31
  32   /* Make sure we are alone.  */
  33   lll_lock (cond->__data.__lock, pshared);
  34
  35   if (cond->__data.__total_seq > cond->__data.__wakeup_seq)
  36     {
  37       /* If there are still some waiters which have not been
  38          woken up, this is an application bug.  */
  39       lll_unlock (cond->__data.__lock, pshared);
  40       return EBUSY;
  41     }
  42
  43   /* Tell pthread_cond_*wait that this condvar is being destroyed.  */
  44   cond->__data.__total_seq = -1ULL;
  45
  46   /* If there are waiters which have been already signalled or
  47      broadcasted, but still are using the pthread_cond_t structure,
  48      pthread_cond_destroy needs to wait for them.  */
  49   unsigned int nwaiters = cond->__data.__nwaiters;
  50
  51   if (nwaiters >= (1 << COND_NWAITERS_SHIFT))
  52     {
  53       /* Wake everybody on the associated mutex in case there are
  54          threads that have been requeued to it.
  55          Without this, pthread_cond_destroy could block potentially
  56          for a long time or forever, as it would depend on other
  57          thread's using the mutex.
  58          When all threads waiting on the mutex are woken up, pthread_cond_wait
  59          only waits for threads to acquire and release the internal
  60          condvar lock.  */
  61       if (cond->__data.__mutex != NULL
  62           && cond->__data.__mutex != (void *) ~0l)
  63         {
  64           pthread_mutex_t *mut = (pthread_mutex_t *) cond->__data.__mutex;
  65           lll_futex_wake (&mut->__data.__lock, INT_MAX,
  66                           PTHREAD_MUTEX_PSHARED (mut));
  67         }
  68
  69       do
  70         {
  71           lll_unlock (cond->__data.__lock, pshared);
  72
  73           lll_futex_wait (&cond->__data.__nwaiters, nwaiters, pshared);
  74
  75           lll_lock (cond->__data.__lock, pshared);
  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);