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 */ 29 30 #include <assert.h> 31 #include <errno.h> 32 #include <unistd.h> 33 #include <sys/time.h> 34 35 #include "thr_private.h" 36 37 #define cpu_ccfence() __asm __volatile("" : : : "memory") 38 39 /* 40 * This function is used to acquire a contested lock. 41 * 42 * A *mtx value of 1 indicates locked normally. 43 * A *mtx value of 2 indicates locked and contested. 44 */ 45 int 46 __thr_umtx_lock(volatile umtx_t *mtx, int id, int timo) 47 { 48 int v, errval, ret = 0; 49 50 id &= 0x3FFFFFFF; 51 /* contested */ 52 for (;;) { 53 v = *mtx; 54 cpu_ccfence(); 55 if (v == 0) { 56 if (atomic_cmpset_acq_int(mtx, 0, id)) { 57 break; 58 } 59 continue; 60 } 61 if ((v & 0x40000000) || 62 atomic_cmpset_acq_int(mtx, v, v|0x40000000)) { 63 if (timo == 0) { 64 _umtx_sleep_err(mtx, v|0x40000000, timo); 65 } else if ((errval = _umtx_sleep_err(mtx, v|0x40000000, timo)) > 0) { 66 if (errval == EAGAIN) { 67 if (atomic_cmpset_acq_int(mtx, 0, id)) 68 ret = 0; 69 else 70 ret = ETIMEDOUT; 71 break; 72 } 73 } 74 } 75 } 76 return (ret); 77 } 78 79 /* 80 * Release a mutex. A contested mutex has a value 81 * of 2, an uncontested mutex has a value of 1. 82 */ 83 void 84 __thr_umtx_unlock(volatile umtx_t *mtx, int id) 85 { 86 int v; 87 88 id &= 0x3FFFFFFF; 89 for (;;) { 90 v = *mtx; 91 cpu_ccfence(); 92 if (atomic_cmpset_acq_int(mtx, v, 0)) { 93 if (v & 0x40000000) 94 _umtx_wakeup_err(mtx, 1); 95 THR_ASSERT((v & 0x3FFFFFFF) == id, 96 "thr_umtx_unlock: wrong owner"); 97 break; 98 } 99 } 100 } 101 102 /* 103 * Low level timed umtx lock. This function must never return 104 * EINTR. 105 */ 106 int 107 __thr_umtx_timedlock(volatile umtx_t *mtx, int id, 108 const struct timespec *timeout) 109 { 110 struct timespec ts, ts2, ts3; 111 int timo, ret; 112 113 if ((timeout->tv_sec < 0) || 114 (timeout->tv_sec == 0 && timeout->tv_nsec <= 0)) { 115 return (ETIMEDOUT); 116 } 117 118 /* XXX there should have MONO timer! */ 119 clock_gettime(CLOCK_REALTIME, &ts); 120 TIMESPEC_ADD(&ts, &ts, timeout); 121 ts2 = *timeout; 122 123 id &= 0x3FFFFFFF; 124 125 for (;;) { 126 if (ts2.tv_nsec) { 127 timo = (int)(ts2.tv_nsec / 1000); 128 if (timo == 0) 129 timo = 1; 130 } else { 131 timo = 1000000; 132 } 133 ret = __thr_umtx_lock(mtx, id, timo); 134 if (ret != EINTR && ret != ETIMEDOUT) 135 break; 136 clock_gettime(CLOCK_REALTIME, &ts3); 137 TIMESPEC_SUB(&ts2, &ts, &ts3); 138 if (ts2.tv_sec < 0 || 139 (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) { 140 ret = ETIMEDOUT; 141 break; 142 } 143 } 144 return (ret); 145 } 146 147 int 148 _thr_umtx_wait(volatile umtx_t *mtx, int exp, const struct timespec *timeout, 149 int clockid) 150 { 151 struct timespec ts, ts2, ts3; 152 int timo, errval, ret = 0; 153 154 cpu_ccfence(); 155 if (*mtx != exp) 156 return (0); 157 158 if (timeout == NULL) { 159 /* 160 * NOTE: If no timeout, EINTR cannot be returned. Ignore 161 * EINTR. 162 */ 163 while ((errval = _umtx_sleep_err(mtx, exp, 10000000)) > 0) { 164 if (errval == EBUSY) 165 break; 166 #if 0 167 if (errval == ETIMEDOUT || errval == EWOULDBLOCK) { 168 if (*mtx != exp) { 169 fprintf(stderr, 170 "thr_umtx_wait: FAULT VALUE CHANGE " 171 "%d -> %d oncond %p\n", 172 exp, *mtx, mtx); 173 } 174 } 175 #endif 176 if (*mtx != exp) 177 return(0); 178 } 179 return (ret); 180 } 181 182 /* 183 * Timed waits can return EINTR 184 */ 185 if ((timeout->tv_sec < 0) || 186 (timeout->tv_sec == 0 && timeout->tv_nsec <= 0)) 187 return (ETIMEDOUT); 188 189 clock_gettime(clockid, &ts); 190 TIMESPEC_ADD(&ts, &ts, timeout); 191 ts2 = *timeout; 192 193 for (;;) { 194 if (ts2.tv_nsec) { 195 timo = (int)(ts2.tv_nsec / 1000); 196 if (timo == 0) 197 timo = 1; 198 } else { 199 timo = 1000000; 200 } 201 202 if ((errval = _umtx_sleep_err(mtx, exp, timo)) > 0) { 203 if (errval == EBUSY) { 204 ret = 0; 205 break; 206 } 207 if (errval == EINTR) { 208 ret = EINTR; 209 break; 210 } 211 } 212 213 clock_gettime(clockid, &ts3); 214 TIMESPEC_SUB(&ts2, &ts, &ts3); 215 if (ts2.tv_sec < 0 || (ts2.tv_sec == 0 && ts2.tv_nsec <= 0)) { 216 ret = ETIMEDOUT; 217 break; 218 } 219 } 220 return (ret); 221 } 222 223 void 224 _thr_umtx_wake(volatile umtx_t *mtx, int count) 225 { 226 _umtx_wakeup_err(mtx, count); 227 } 228