1 /* $NetBSD: pthread_barrier.c,v 1.5 2003/02/15 00:52:18 nathanw Exp $ */ 2 3 /*- 4 * Copyright (c) 2001, 2003 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, and by Jason R. Thorpe. 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 <errno.h> 40 #include <sys/cdefs.h> 41 42 #include "pthread.h" 43 #include "pthread_int.h" 44 45 #undef PTHREAD_BARRIER_DEBUG 46 47 #ifdef PTHREAD_BARRIER_DEBUG 48 #define SDPRINTF(x) DPRINTF(x) 49 #else 50 #define SDPRINTF(x) 51 #endif 52 53 int 54 pthread_barrier_init(pthread_barrier_t *barrier, 55 const pthread_barrierattr_t *attr, unsigned int count) 56 { 57 pthread_t self; 58 59 #ifdef ERRORCHECK 60 if ((barrier == NULL) || 61 (attr && (attr->ptba_magic != _PT_BARRIERATTR_MAGIC))) 62 return EINVAL; 63 #endif 64 65 if (count == 0) 66 return EINVAL; 67 68 self = pthread__self(); 69 70 if (barrier->ptb_magic == _PT_BARRIER_MAGIC) { 71 /* 72 * We're simply reinitializing the barrier to a 73 * new count. 74 */ 75 pthread_spinlock(self, &barrier->ptb_lock); 76 77 if (barrier->ptb_magic != _PT_BARRIER_MAGIC) { 78 pthread_spinunlock(self, &barrier->ptb_lock); 79 return EINVAL; 80 } 81 82 if (!PTQ_EMPTY(&barrier->ptb_waiters)) { 83 pthread_spinunlock(self, &barrier->ptb_lock); 84 return EBUSY; 85 } 86 87 barrier->ptb_initcount = count; 88 barrier->ptb_curcount = 0; 89 barrier->ptb_generation = 0; 90 91 pthread_spinunlock(self, &barrier->ptb_lock); 92 93 return 0; 94 } 95 96 barrier->ptb_magic = _PT_BARRIER_MAGIC; 97 pthread_lockinit(&barrier->ptb_lock); 98 PTQ_INIT(&barrier->ptb_waiters); 99 barrier->ptb_initcount = count; 100 barrier->ptb_curcount = 0; 101 barrier->ptb_generation = 0; 102 103 return 0; 104 } 105 106 107 int 108 pthread_barrier_destroy(pthread_barrier_t *barrier) 109 { 110 pthread_t self; 111 112 #ifdef ERRORCHECK 113 if ((barrier == NULL) || (barrier->ptb_magic != _PT_BARRIER_MAGIC)) 114 return EINVAL; 115 #endif 116 117 self = pthread__self(); 118 119 pthread_spinlock(self, &barrier->ptb_lock); 120 121 if (barrier->ptb_magic != _PT_BARRIER_MAGIC) { 122 pthread_spinunlock(self, &barrier->ptb_lock); 123 return EINVAL; 124 } 125 126 if (!PTQ_EMPTY(&barrier->ptb_waiters)) { 127 pthread_spinunlock(self, &barrier->ptb_lock); 128 return EBUSY; 129 } 130 131 barrier->ptb_magic = _PT_BARRIER_DEAD; 132 133 pthread_spinunlock(self, &barrier->ptb_lock); 134 135 return 0; 136 } 137 138 139 int 140 pthread_barrier_wait(pthread_barrier_t *barrier) 141 { 142 pthread_t self; 143 unsigned int gen; 144 145 #ifdef ERRORCHECK 146 if ((barrier == NULL) || (barrier->ptb_magic != _PT_BARRIER_MAGIC)) 147 return EINVAL; 148 #endif 149 self = pthread__self(); 150 151 pthread_spinlock(self, &barrier->ptb_lock); 152 153 /* 154 * A single arbitrary thread is supposed to return 155 * PTHREAD_BARRIER_SERIAL_THREAD, and everone else 156 * is supposed to return 0. Since pthread_barrier_wait() 157 * is not a cancellation point, this is trivial; we 158 * simply elect that the thread that causes the barrier 159 * to be satisfied gets the special return value. Note 160 * that this final thread does not actually need to block, 161 * but instead is responsible for waking everyone else up. 162 */ 163 if (barrier->ptb_curcount + 1 == barrier->ptb_initcount) { 164 struct pthread_queue_t blockedq; 165 166 SDPRINTF(("(barrier wait %p) Satisfied %p\n", 167 self, barrier)); 168 169 blockedq = barrier->ptb_waiters; 170 PTQ_INIT(&barrier->ptb_waiters); 171 barrier->ptb_curcount = 0; 172 barrier->ptb_generation++; 173 174 pthread__sched_sleepers(self, &blockedq); 175 176 pthread_spinunlock(self, &barrier->ptb_lock); 177 178 return PTHREAD_BARRIER_SERIAL_THREAD; 179 } 180 181 barrier->ptb_curcount++; 182 gen = barrier->ptb_generation; 183 while (gen == barrier->ptb_generation) { 184 SDPRINTF(("(barrier wait %p) Waiting on %p\n", 185 self, barrier)); 186 187 pthread_spinlock(self, &self->pt_statelock); 188 189 self->pt_state = PT_STATE_BLOCKED_QUEUE; 190 self->pt_sleepobj = barrier; 191 self->pt_sleepq = &barrier->ptb_waiters; 192 self->pt_sleeplock = &barrier->ptb_lock; 193 194 pthread_spinunlock(self, &self->pt_statelock); 195 196 PTQ_INSERT_TAIL(&barrier->ptb_waiters, self, pt_sleep); 197 198 pthread__block(self, &barrier->ptb_lock); 199 SDPRINTF(("(barrier wait %p) Woke up on %p\n", 200 self, barrier)); 201 /* Spinlock is unlocked on return */ 202 pthread_spinlock(self, &barrier->ptb_lock); 203 } 204 pthread_spinunlock(self, &barrier->ptb_lock); 205 206 return 0; 207 } 208 209 210 int 211 pthread_barrierattr_init(pthread_barrierattr_t *attr) 212 { 213 214 #ifdef ERRORCHECK 215 if (attr == NULL) 216 return EINVAL; 217 #endif 218 219 attr->ptba_magic = _PT_BARRIERATTR_MAGIC; 220 221 return 0; 222 } 223 224 225 int 226 pthread_barrierattr_destroy(pthread_barrierattr_t *attr) 227 { 228 229 #ifdef ERRORCHECK 230 if ((attr == NULL) || 231 (attr->ptba_magic != _PT_BARRIERATTR_MAGIC)) 232 return EINVAL; 233 #endif 234 235 attr->ptba_magic = _PT_BARRIERATTR_DEAD; 236 237 return 0; 238 } 239