1 /* 2 * pte_spinlock_check_need_init.c 3 * 4 * Description: 5 * This translation unit implements spin lock primitives. 6 * 7 * -------------------------------------------------------------------------- 8 * 9 * Pthreads-embedded (PTE) - POSIX Threads Library for embedded systems 10 * Copyright(C) 2008 Jason Schmidlapp 11 * 12 * Contact Email: jschmidlapp@users.sourceforge.net 13 * 14 * 15 * Based upon Pthreads-win32 - POSIX Threads Library for Win32 16 * Copyright(C) 1998 John E. Bossom 17 * Copyright(C) 1999,2005 Pthreads-win32 contributors 18 * 19 * Contact Email: rpj@callisto.canberra.edu.au 20 * 21 * The original list of contributors to the Pthreads-win32 project 22 * is contained in the file CONTRIBUTORS.ptw32 included with the 23 * source code distribution. The list can also be seen at the 24 * following World Wide Web location: 25 * http://sources.redhat.com/pthreads-win32/contributors.html 26 * 27 * This library is free software; you can redistribute it and/or 28 * modify it under the terms of the GNU Lesser General Public 29 * License as published by the Free Software Foundation; either 30 * version 2 of the License, or (at your option) any later version. 31 * 32 * This library is distributed in the hope that it will be useful, 33 * but WITHOUT ANY WARRANTY; without even the implied warranty of 34 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 35 * Lesser General Public License for more details. 36 * 37 * You should have received a copy of the GNU Lesser General Public 38 * License along with this library in the file COPYING.LIB; 39 * if not, write to the Free Software Foundation, Inc., 40 * 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA 41 */ 42 43 #include "pthread.h" 44 #include "implement.h" 45 46 47 int 48 pte_spinlock_check_need_init (pthread_spinlock_t * lock) 49 { 50 int result = 0; 51 52 /* 53 * The following guarded test is specifically for statically 54 * initialised spinlocks (via PTHREAD_SPINLOCK_INITIALIZER). 55 * 56 * Note that by not providing this synchronisation we risk 57 * introducing race conditions into applications which are 58 * correctly written. 59 */ 60 61 62 pte_osMutexLock (pte_spinlock_test_init_lock); 63 64 /* 65 * We got here possibly under race 66 * conditions. Check again inside the critical section 67 * and only initialise if the spinlock is valid (not been destroyed). 68 * If a static spinlock has been destroyed, the application can 69 * re-initialise it only by calling pthread_spin_init() 70 * explicitly. 71 */ 72 if (*lock == PTHREAD_SPINLOCK_INITIALIZER) 73 { 74 result = pthread_spin_init (lock, PTHREAD_PROCESS_PRIVATE); 75 } 76 else if (*lock == NULL) 77 { 78 /* 79 * The spinlock has been destroyed while we were waiting to 80 * initialise it, so the operation that caused the 81 * auto-initialisation should fail. 82 */ 83 result = EINVAL; 84 } 85 86 pte_osMutexUnlock(pte_spinlock_test_init_lock); 87 88 return (result); 89 } 90