native_client_sdk/src/libraries/third_party/pthreads-win32/pthread_spin_destroy.c

   1 /*
   2  * pthread_spin_destroy.c
   3  *
   4  * Description:
   5  * This translation unit implements spin lock primitives.
   6  *
   7  * --------------------------------------------------------------------------
   8  *
   9  *      Pthreads-win32 - POSIX Threads Library for Win32
  10  *      Copyright(C) 1998 John E. Bossom
  11  *      Copyright(C) 1999,2005 Pthreads-win32 contributors
  12  *
  13  *      Contact Email: rpj@callisto.canberra.edu.au
  14  *
  15  *      The current list of contributors is contained
  16  *      in the file CONTRIBUTORS included with the source
  17  *      code distribution. The list can also be seen at the
  18  *      following World Wide Web location:
  19  *      http://sources.redhat.com/pthreads-win32/contributors.html
  20  *
  21  *      This library is free software; you can redistribute it and/or
  22  *      modify it under the terms of the GNU Lesser General Public
  23  *      License as published by the Free Software Foundation; either
  24  *      version 2 of the License, or (at your option) any later version.
  25  *
  26  *      This library is distributed in the hope that it will be useful,
  27  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  28  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  29  *      Lesser General Public License for more details.
  30  *
  31  *      You should have received a copy of the GNU Lesser General Public
  32  *      License along with this library in the file COPYING.LIB;
  33  *      if not, write to the Free Software Foundation, Inc.,
  34  *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  35  */
  36
  37 #include "pthread.h"
  38 #include "implement.h"
  39
  40
  41 int
  42 pthread_spin_destroy (pthread_spinlock_t * lock)
  43 {
  44   register pthread_spinlock_t s;
  45   int result = 0;
  46
  47   if (lock == NULL || *lock == NULL)
  48     {
  49       return EINVAL;
  50     }
  51
  52   if ((s = *lock) != PTHREAD_SPINLOCK_INITIALIZER)
  53     {
  54       if (s->interlock == PTW32_SPIN_USE_MUTEX)
  55         {
  56           result = pthread_mutex_destroy (&(s->u.mutex));
  57         }
  58       else if ((PTW32_INTERLOCKED_LONG) PTW32_SPIN_UNLOCKED !=
  59                PTW32_INTERLOCKED_COMPARE_EXCHANGE_LONG ((PTW32_INTERLOCKED_LONGPTR) &s->interlock,
  60                                                    (PTW32_INTERLOCKED_LONG) PTW32_SPIN_INVALID,
  61                                                    (PTW32_INTERLOCKED_LONG) PTW32_SPIN_UNLOCKED))
  62         {
  63           result = EINVAL;
  64         }
  65
  66       if (0 == result)
  67         {
  68           /*
  69            * We are relying on the application to ensure that all other threads
  70            * have finished with the spinlock before destroying it.
  71            */
  72           *lock = NULL;
  73           (void) free (s);
  74         }
  75     }
  76   else
  77     {
  78       /*
  79        * See notes in ptw32_spinlock_check_need_init() above also.
  80        */
  81       ptw32_mcs_local_node_t node;
  82
  83       ptw32_mcs_lock_acquire(&ptw32_spinlock_test_init_lock, &node);
  84
  85       /*
  86        * Check again.
  87        */
  88       if (*lock == PTHREAD_SPINLOCK_INITIALIZER)
  89         {
  90           /*
  91            * This is all we need to do to destroy a statically
  92            * initialised spinlock that has not yet been used (initialised).
  93            * If we get to here, another thread
  94            * waiting to initialise this mutex will get an EINVAL.
  95            */
  96           *lock = NULL;
  97         }
  98       else
  99         {
 100           /*
 101            * The spinlock has been initialised while we were waiting
 102            * so assume it's in use.
 103            */
 104           result = EBUSY;
 105         }
 106
 107        ptw32_mcs_lock_release(&node);
 108     }
 109
 110   return (result);
 111 }