pthread_lock.c revision 1.20.2.1
1 /* $NetBSD: pthread_lock.c,v 1.20.2.1 2007/07/18 13:36:19 skrll Exp $ */ 2 3 /*- 4 * Copyright (c) 2001, 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 and 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_lock.c,v 1.20.2.1 2007/07/18 13:36:19 skrll Exp $"); 41 42 #include <sys/types.h> 43 #include <sys/lock.h> 44 #include <sys/ras.h> 45 46 #include <errno.h> 47 #include <unistd.h> 48 #include <stdio.h> 49 50 #include "pthread.h" 51 #include "pthread_int.h" 52 53 #ifdef PTHREAD_SPIN_DEBUG_PRINT 54 #define SDPRINTF(x) DPRINTF(x) 55 #else 56 #define SDPRINTF(x) 57 #endif 58 59 /* This does not belong here. */ 60 #if defined(i386) || defined(__x86_64__) 61 #define smt_pause() __asm __volatile("rep; nop" ::: "memory") 62 #else 63 #define smt_pause() /* nothing */ 64 #endif 65 66 extern int pthread__nspins; 67 static int pthread__atomic; 68 69 RAS_DECL(pthread__lock); 70 71 void 72 pthread__simple_lock_init(__cpu_simple_lock_t *alp) 73 { 74 75 if (pthread__atomic) { 76 __cpu_simple_lock_init(alp); 77 return; 78 } 79 80 __cpu_simple_lock_clear(alp); 81 } 82 83 int 84 pthread__simple_lock_try(__cpu_simple_lock_t *alp) 85 { 86 __cpu_simple_lock_t old; 87 __cpu_simple_lock_t locked = __SIMPLELOCK_LOCKED; 88 89 if (pthread__atomic) 90 return __cpu_simple_lock_try(alp); 91 92 RAS_START(pthread__lock); 93 old = *alp; 94 *alp = locked; 95 RAS_END(pthread__lock); 96 97 return __SIMPLELOCK_UNLOCKED_P(&old); 98 } 99 100 inline void 101 pthread__simple_unlock(__cpu_simple_lock_t *alp) 102 { 103 104 if (pthread__atomic) { 105 __cpu_simple_unlock(alp); 106 return; 107 } 108 109 __cpu_simple_lock_clear(alp); 110 } 111 112 /* 113 * Initialize the locking primitives. On uniprocessors, we always 114 * use Restartable Atomic Sequences if they are available. Otherwise, 115 * we fall back onto machine-dependent atomic lock primitives. 116 */ 117 void 118 pthread__lockprim_init(int ncpu) 119 { 120 121 if (ncpu != 1) { 122 pthread__atomic = 1; 123 return; 124 } 125 126 if (rasctl(RAS_ADDR(pthread__lock), RAS_SIZE(pthread__lock), 127 RAS_INSTALL) != 0) { 128 pthread__atomic = 1; 129 return; 130 } 131 } 132 133 void 134 pthread_lockinit(pthread_spin_t *lock) 135 { 136 137 pthread__simple_lock_init(lock); 138 } 139 140 void 141 pthread_spinlock(pthread_t thread, pthread_spin_t *lock) 142 { 143 int count, ret; 144 145 count = pthread__nspins; 146 SDPRINTF(("(pthread_spinlock %p) spinlock %p (count %d)\n", 147 thread, lock, thread->pt_spinlocks)); 148 #ifdef PTHREAD_SPIN_DEBUG 149 pthread__assert(thread->pt_spinlocks >= 0); 150 #endif 151 152 thread->pt_spinlocks++; 153 if (__predict_true(pthread__simple_lock_try(lock))) { 154 PTHREADD_ADD(PTHREADD_SPINLOCKS); 155 return; 156 } 157 158 do { 159 while ((ret = pthread__simple_lock_try(lock)) == 0 && 160 --count) { 161 smt_pause(); 162 } 163 164 if (ret == 1) 165 break; 166 167 SDPRINTF(("(pthread_spinlock %p) retrying spinlock %p " 168 "(count %d)\n", thread, lock, 169 thread->pt_spinlocks)); 170 thread->pt_spinlocks--; 171 172 /* XXXLWP far from ideal */ 173 sched_yield(); 174 count = pthread__nspins; 175 thread->pt_spinlocks++; 176 } while (/*CONSTCOND*/ 1); 177 178 PTHREADD_ADD(PTHREADD_SPINLOCKS); 179 } 180 181 int 182 pthread_spintrylock(pthread_t thread, pthread_spin_t *lock) 183 { 184 int ret; 185 186 SDPRINTF(("(pthread_spintrylock %p) spinlock %p (count %d)\n", 187 thread, lock, thread->pt_spinlocks)); 188 189 thread->pt_spinlocks++; 190 ret = pthread__simple_lock_try(lock); 191 if (!ret) 192 thread->pt_spinlocks--; 193 194 return ret; 195 } 196 197 void 198 pthread_spinunlock(pthread_t thread, pthread_spin_t *lock) 199 { 200 201 SDPRINTF(("(pthread_spinunlock %p) spinlock %p (count %d)\n", 202 thread, lock, thread->pt_spinlocks)); 203 204 pthread__simple_unlock(lock); 205 thread->pt_spinlocks--; 206 #ifdef PTHREAD_SPIN_DEBUG 207 pthread__assert(thread->pt_spinlocks >= 0); 208 #endif 209 PTHREADD_ADD(PTHREADD_SPINUNLOCKS); 210 } 211 212 213 /* 214 * Public (POSIX-specified) spinlocks. 215 */ 216 int 217 pthread_spin_init(pthread_spinlock_t *lock, int pshared) 218 { 219 220 #ifdef ERRORCHECK 221 if (lock == NULL || (pshared != PTHREAD_PROCESS_PRIVATE && 222 pshared != PTHREAD_PROCESS_SHARED)) 223 return EINVAL; 224 #endif 225 lock->pts_magic = _PT_SPINLOCK_MAGIC; 226 227 /* 228 * We don't actually use the pshared flag for anything; 229 * CPU simple locks have all the process-shared properties 230 * that we want anyway. 231 */ 232 lock->pts_flags = pshared; 233 pthread_lockinit(&lock->pts_spin); 234 235 return 0; 236 } 237 238 int 239 pthread_spin_destroy(pthread_spinlock_t *lock) 240 { 241 242 #ifdef ERRORCHECK 243 if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC) 244 return EINVAL; 245 if (!__SIMPLELOCK_UNLOCKED_P(&lock->pts_spin)) 246 return EBUSY; 247 #endif 248 249 lock->pts_magic = _PT_SPINLOCK_DEAD; 250 251 return 0; 252 } 253 254 int 255 pthread_spin_lock(pthread_spinlock_t *lock) 256 { 257 258 #ifdef ERRORCHECK 259 if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC) 260 return EINVAL; 261 #endif 262 263 while (pthread__simple_lock_try(&lock->pts_spin) == 0) { 264 smt_pause(); 265 } 266 267 return 0; 268 } 269 270 int 271 pthread_spin_trylock(pthread_spinlock_t *lock) 272 { 273 274 #ifdef ERRORCHECK 275 if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC) 276 return EINVAL; 277 #endif 278 279 if (pthread__simple_lock_try(&lock->pts_spin) == 0) 280 return EBUSY; 281 282 return 0; 283 } 284 285 int 286 pthread_spin_unlock(pthread_spinlock_t *lock) 287 { 288 289 #ifdef ERRORCHECK 290 if (lock == NULL || lock->pts_magic != _PT_SPINLOCK_MAGIC) 291 return EINVAL; 292 #endif 293 294 pthread__simple_unlock(&lock->pts_spin); 295 296 return 0; 297 } 298
Indexes created Mon Sep 22 05:09:51 GMT 2025