1 /*- 2 * Copyright (c) 2005 David Xu <davidxu@freebsd.org> 3 * Copyright (c) 2005 Matthew Dillon <dillon@backplane.com> 4 * 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 * 28 * $DragonFly: src/lib/libthread_xu/thread/thr_umtx.c,v 1.4 2008/04/14 20:12:41 dillon Exp $ 29 */ 30 31 #include <assert.h> 32 #include <errno.h> 33 #include <unistd.h> 34 #include <sys/time.h> 35 36 #include "thr_private.h" 37 38 /* 39 * This function is used to acquire a contested lock. 40 */ 41 int 42 __thr_umtx_lock(volatile umtx_t *mtx, int timo) 43 { 44 int v, errval, ret = 0; 45 46 /* contested */ 47 do { 48 v = *mtx; 49 if (v == 2 || atomic_cmpset_acq_int(mtx, 1, 2)) { 50 if (timo == 0) 51 _umtx_sleep_err(mtx, 2, timo); 52 else if ( (errval = _umtx_sleep_err(mtx, 2, timo)) > 0) { 53 if (errval == EAGAIN) { 54 if (atomic_cmpset_acq_int(mtx, 0, 2)) 55 ret = 0; 56 else 57 ret = ETIMEDOUT; 58 break; 59 } 60 } 61 } 62 } while (!atomic_cmpset_acq_int(mtx, 0, 2)); 63 64 return (ret); 65 } 66 67 void 68 __thr_umtx_unlock(volatile umtx_t *mtx) 69 { 70 int v; 71 72 for (;;) { 73 v = *mtx; 74 if (atomic_cmpset_acq_int(mtx, v, v-1)) { 75 if (v != 1) { 76 *mtx = 0; 77 _umtx_wakeup_err(mtx, 1); 78 } 79 break; 80 } 81 } 82 } 83 84 /* 85 * Low level timed umtx lock. This function must never return 86 * EINTR. 87 */ 88 int 89 __thr_umtx_timedlock(volatile umtx_t *mtx, const struct timespec *timeout) 90 { 91 struct timespec ts, ts2, ts3; 92 int timo, ret; 93 94 if ((timeout->tv_sec < 0) || 95 (timeout->tv_sec == 0 && timeout->tv_nsec <= 0)) 96 return (ETIMEDOUT); 97 98 /* XXX there should have MONO timer! */ 99 clock_gettime(CLOCK_REALTIME, &ts); 100 TIMESPEC_ADD(&ts, &ts, timeout); 101 ts2 = *timeout; 102 103 for (;;) { 104 if (ts2.tv_nsec) { 105 timo = (int)(ts2.tv_nsec / 1000); 106 if (timo == 0) 107 timo = 1; 108 } else { 109 timo = 1000000; 110 } 111 ret = __thr_umtx_lock(mtx, timo); 112 if (ret != EINTR && ret != ETIMEDOUT) 113 break; 114 clock_gettime(CLOCK_REALTIME, &ts3); 115 TIMESPEC_SUB(&ts2, &ts, &ts3); 116 if (ts2.tv_sec < 0 || (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) { 117 ret = ETIMEDOUT; 118 break; 119 } 120 } 121 return (ret); 122 } 123 124 int 125 _thr_umtx_wait(volatile umtx_t *mtx, int exp, const struct timespec *timeout, 126 int clockid) 127 { 128 struct timespec ts, ts2, ts3; 129 int timo, errval, ret = 0; 130 131 if (*mtx != exp) 132 return (0); 133 134 if (timeout == NULL) { 135 while ( (errval = _umtx_sleep_err(mtx, exp, 10000000)) > 0) { 136 if (errval == EBUSY) 137 break; 138 if (errval == EINTR) { 139 ret = EINTR; 140 break; 141 } 142 #if 0 143 if (errval == ETIMEDOUT || errval == EWOULDBLOCK) { 144 if (*mtx != exp) { 145 fprintf(stderr, 146 "thr_umtx_wait: FAULT VALUE CHANGE " 147 "%d -> %d oncond %p\n", 148 exp, *mtx, mtx); 149 } 150 } 151 #endif 152 if (*mtx != exp) 153 return(0); 154 } 155 return (ret); 156 } 157 158 if ((timeout->tv_sec < 0) || 159 (timeout->tv_sec == 0 && timeout->tv_nsec <= 0)) 160 return (ETIMEDOUT); 161 162 clock_gettime(clockid, &ts); 163 TIMESPEC_ADD(&ts, &ts, timeout); 164 ts2 = *timeout; 165 166 for (;;) { 167 if (ts2.tv_nsec) { 168 timo = (int)(ts2.tv_nsec / 1000); 169 if (timo == 0) 170 timo = 1; 171 } else { 172 timo = 1000000; 173 } 174 if ( (errval = _umtx_sleep_err(mtx, exp, timo)) > 0) { 175 if (errval == EBUSY) { 176 ret = 0; 177 break; 178 } else if (errval == EINTR) { 179 ret = EINTR; 180 break; 181 } 182 } 183 clock_gettime(clockid, &ts3); 184 TIMESPEC_SUB(&ts2, &ts, &ts3); 185 if (ts2.tv_sec < 0 || (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) { 186 ret = ETIMEDOUT; 187 break; 188 } 189 } 190 return (ret); 191 } 192 193 void _thr_umtx_wake(volatile umtx_t *mtx, int count) 194 { 195 _umtx_wakeup_err(mtx, count); 196 } 197