1 /* 2 * pthread_rwlock_check_need_init.c 3 * 4 * Description: 5 * This translation unit implements read/write 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 (at) 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 INLINE int 41 ptw32_rwlock_check_need_init (pthread_rwlock_t * rwlock) 42 { 43 int result = 0; 44 ptw32_mcs_local_node_t node; 45 46 /* 47 * The following guarded test is specifically for statically 48 * initialised rwlocks (via PTHREAD_RWLOCK_INITIALIZER). 49 */ 50 ptw32_mcs_lock_acquire(&ptw32_rwlock_test_init_lock, &node); 51 52 /* 53 * We got here possibly under race 54 * conditions. Check again inside the critical section 55 * and only initialise if the rwlock is valid (not been destroyed). 56 * If a static rwlock has been destroyed, the application can 57 * re-initialise it only by calling pthread_rwlock_init() 58 * explicitly. 59 */ 60 if (*rwlock == PTHREAD_RWLOCK_INITIALIZER) 61 { 62 result = pthread_rwlock_init (rwlock, NULL); 63 } 64 else if (*rwlock == NULL) 65 { 66 /* 67 * The rwlock has been destroyed while we were waiting to 68 * initialise it, so the operation that caused the 69 * auto-initialisation should fail. 70 */ 71 result = EINVAL; 72 } 73 74 ptw32_mcs_lock_release(&node); 75 76 return result; 77 } 78
