pthread_barrier.c revision 1.15
1 /* $NetBSD: pthread_barrier.c,v 1.15 2007/11/13 15:57:11 ad Exp $ */ 2 3 /*- 4 * Copyright (c) 2001, 2003, 2006, 2007 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Nathan J. Williams, by Jason R. Thorpe, and by Andrew Doran. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 #include <sys/cdefs.h> 40 __RCSID("$NetBSD: pthread_barrier.c,v 1.15 2007/11/13 15:57:11 ad Exp $"); 41 42 #include <errno.h> 43 44 #include "pthread.h" 45 #include "pthread_int.h" 46 47 #undef PTHREAD_BARRIER_DEBUG 48 49 #ifdef PTHREAD_BARRIER_DEBUG 50 #define SDPRINTF(x) DPRINTF(x) 51 #else 52 #define SDPRINTF(x) 53 #endif 54 55 int 56 pthread_barrier_init(pthread_barrier_t *barrier, 57 const pthread_barrierattr_t *attr, unsigned int count) 58 { 59 pthread_t self; 60 61 #ifdef ERRORCHECK 62 if ((barrier == NULL) || 63 (attr && (attr->ptba_magic != _PT_BARRIERATTR_MAGIC))) 64 return EINVAL; 65 #endif 66 67 if (count == 0) 68 return EINVAL; 69 70 if (barrier->ptb_magic == _PT_BARRIER_MAGIC) { 71 self = pthread__self(); 72 73 /* 74 * We're simply reinitializing the barrier to a 75 * new count. 76 */ 77 pthread__spinlock(self, &barrier->ptb_lock); 78 79 if (barrier->ptb_magic != _PT_BARRIER_MAGIC) { 80 pthread__spinunlock(self, &barrier->ptb_lock); 81 return EINVAL; 82 } 83 84 if (!PTQ_EMPTY(&barrier->ptb_waiters)) { 85 pthread__spinunlock(self, &barrier->ptb_lock); 86 return EBUSY; 87 } 88 89 barrier->ptb_initcount = count; 90 barrier->ptb_curcount = 0; 91 barrier->ptb_generation = 0; 92 93 pthread__spinunlock(self, &barrier->ptb_lock); 94 95 return 0; 96 } 97 98 barrier->ptb_magic = _PT_BARRIER_MAGIC; 99 pthread_lockinit(&barrier->ptb_lock); 100 PTQ_INIT(&barrier->ptb_waiters); 101 barrier->ptb_initcount = count; 102 barrier->ptb_curcount = 0; 103 barrier->ptb_generation = 0; 104 105 return 0; 106 } 107 108 109 int 110 pthread_barrier_destroy(pthread_barrier_t *barrier) 111 { 112 pthread_t self; 113 114 #ifdef ERRORCHECK 115 if ((barrier == NULL) || (barrier->ptb_magic != _PT_BARRIER_MAGIC)) 116 return EINVAL; 117 #endif 118 119 self = pthread__self(); 120 pthread__spinlock(self, &barrier->ptb_lock); 121 122 if (barrier->ptb_magic != _PT_BARRIER_MAGIC) { 123 pthread__spinunlock(self, &barrier->ptb_lock); 124 return EINVAL; 125 } 126 127 if (!PTQ_EMPTY(&barrier->ptb_waiters)) { 128 pthread__spinunlock(self, &barrier->ptb_lock); 129 return EBUSY; 130 } 131 132 barrier->ptb_magic = _PT_BARRIER_DEAD; 133 134 pthread__spinunlock(self, &barrier->ptb_lock); 135 136 return 0; 137 } 138 139 140 int 141 pthread_barrier_wait(pthread_barrier_t *barrier) 142 { 143 pthread_t self; 144 unsigned int gen; 145 146 #ifdef ERRORCHECK 147 if ((barrier == NULL) || (barrier->ptb_magic != _PT_BARRIER_MAGIC)) 148 return EINVAL; 149 #endif 150 self = pthread__self(); 151 152 pthread__spinlock(self, &barrier->ptb_lock); 153 154 /* 155 * A single arbitrary thread is supposed to return 156 * PTHREAD_BARRIER_SERIAL_THREAD, and everone else 157 * is supposed to return 0. Since pthread_barrier_wait() 158 * is not a cancellation point, this is trivial; we 159 * simply elect that the thread that causes the barrier 160 * to be satisfied gets the special return value. Note 161 * that this final thread does not actually need to block, 162 * but instead is responsible for waking everyone else up. 163 */ 164 if (barrier->ptb_curcount + 1 == barrier->ptb_initcount) { 165 SDPRINTF(("(barrier wait %p) Satisfied %p\n", 166 self, barrier)); 167 168 barrier->ptb_generation++; 169 pthread__unpark_all(self, &barrier->ptb_lock, 170 &barrier->ptb_waiters); 171 return PTHREAD_BARRIER_SERIAL_THREAD; 172 } 173 174 barrier->ptb_curcount++; 175 gen = barrier->ptb_generation; 176 while (gen == barrier->ptb_generation) { 177 SDPRINTF(("(barrier wait %p) Waiting on %p\n", 178 self, barrier)); 179 PTQ_INSERT_TAIL(&barrier->ptb_waiters, self, pt_sleep); 180 self->pt_sleeponq = 1; 181 self->pt_sleepobj = &barrier->ptb_waiters; 182 pthread__spinunlock(self, &barrier->ptb_lock); 183 (void)pthread__park(self, &barrier->ptb_lock, 184 &barrier->ptb_waiters, NULL, 0, 185 &barrier->ptb_waiters); 186 SDPRINTF(("(barrier wait %p) Woke up on %p\n", 187 self, barrier)); 188 pthread__spinlock(self, &barrier->ptb_lock); 189 } 190 pthread__spinunlock(self, &barrier->ptb_lock); 191 192 return 0; 193 } 194 195 196 int 197 pthread_barrierattr_init(pthread_barrierattr_t *attr) 198 { 199 200 #ifdef ERRORCHECK 201 if (attr == NULL) 202 return EINVAL; 203 #endif 204 205 attr->ptba_magic = _PT_BARRIERATTR_MAGIC; 206 207 return 0; 208 } 209 210 211 int 212 pthread_barrierattr_destroy(pthread_barrierattr_t *attr) 213 { 214 215 #ifdef ERRORCHECK 216 if ((attr == NULL) || 217 (attr->ptba_magic != _PT_BARRIERATTR_MAGIC)) 218 return EINVAL; 219 #endif 220 221 attr->ptba_magic = _PT_BARRIERATTR_DEAD; 222 223 return 0; 224 } 225
Indexes created Sat Sep 20 22:09:52 GMT 2025