| 1 | /* |
| 2 | * Copyright (C) 2005 David Xu <davidxu@freebsd.org>. |
| 3 | * Copyright (C) 2000 Jason Evans <jasone@freebsd.org>. |
| 4 | * All rights reserved. |
| 5 | * |
| 6 | * Redistribution and use in source and binary forms, with or without |
| 7 | * modification, are permitted provided that the following conditions |
| 8 | * are met: |
| 9 | * 1. Redistributions of source code must retain the above copyright |
| 10 | * notice(s), this list of conditions and the following disclaimer as |
| 11 | * the first lines of this file unmodified other than the possible |
| 12 | * addition of one or more copyright notices. |
| 13 | * 2. Redistributions in binary form must reproduce the above copyright |
| 14 | * notice(s), this list of conditions and the following disclaimer in |
| 15 | * the documentation and/or other materials provided with the |
| 16 | * distribution. |
| 17 | * |
| 18 | * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDER(S) ``AS IS'' AND ANY |
| 19 | * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE |
| 20 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR |
| 21 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) BE |
| 22 | * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR |
| 23 | * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF |
| 24 | * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR |
| 25 | * BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, |
| 26 | * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE |
| 27 | * OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, |
| 28 | * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| 29 | * |
| 30 | * $DragonFly: src/lib/libthread_xu/thread/thr_sem.c,v 1.6 2007/06/26 23:30:05 josepht Exp $ |
| 31 | */ |
| 32 | |
| 33 | #include "namespace.h" |
| 34 | #include <machine/tls.h> |
| 35 | #include <sys/semaphore.h> |
| 36 | #include <sys/mman.h> |
| 37 | |
| 38 | #include <errno.h> |
| 39 | #include <fcntl.h> |
| 40 | #include <pthread.h> |
| 41 | #include <stdlib.h> |
| 42 | #include <time.h> |
| 43 | #include "un-namespace.h" |
| 44 | #include "thr_private.h" |
| 45 | |
| 46 | /* |
| 47 | * Semaphore definitions. |
| 48 | */ |
| 49 | struct sem { |
| 50 | u_int32_t magic; |
| 51 | volatile umtx_t count; |
| 52 | int semid; |
| 53 | int unused; /* pad */ |
| 54 | }; |
| 55 | |
| 56 | #define SEM_MAGIC ((u_int32_t) 0x09fa4012) |
| 57 | |
| 58 | #define SEMID_LWP 0 |
| 59 | #define SEMID_FORK 1 |
| 60 | |
| 61 | static inline int |
| 62 | sem_check_validity(sem_t *sem) |
| 63 | { |
| 64 | |
| 65 | if ((sem != NULL) && ((*sem)->magic == SEM_MAGIC)) { |
| 66 | return (0); |
| 67 | } else { |
| 68 | errno = EINVAL; |
| 69 | return (-1); |
| 70 | } |
| 71 | } |
| 72 | |
| 73 | static sem_t |
| 74 | sem_alloc(unsigned int value, int pshared) |
| 75 | { |
| 76 | sem_t sem; |
| 77 | int semid; |
| 78 | |
| 79 | if (value > SEM_VALUE_MAX) { |
| 80 | errno = EINVAL; |
| 81 | return (NULL); |
| 82 | } |
| 83 | if (pshared) { |
| 84 | static __thread sem_t sem_base; |
| 85 | static __thread int sem_count; |
| 86 | |
| 87 | if (sem_base == NULL) { |
| 88 | sem_base = mmap(NULL, getpagesize(), |
| 89 | PROT_READ | PROT_WRITE, |
| 90 | MAP_ANON | MAP_SHARED, |
| 91 | -1, 0); |
| 92 | sem_count = getpagesize() / sizeof(*sem); |
| 93 | } |
| 94 | sem = sem_base++; |
| 95 | if (--sem_count == 0) |
| 96 | sem_base = NULL; |
| 97 | semid = SEMID_FORK; |
| 98 | } else { |
| 99 | sem = malloc(sizeof(struct sem)); |
| 100 | semid = SEMID_LWP; |
| 101 | } |
| 102 | if (sem == NULL) { |
| 103 | errno = ENOSPC; |
| 104 | return (NULL); |
| 105 | } |
| 106 | sem->magic = SEM_MAGIC; |
| 107 | sem->count = (u_int32_t)value; |
| 108 | sem->semid = semid; |
| 109 | return (sem); |
| 110 | } |
| 111 | |
| 112 | int |
| 113 | _sem_init(sem_t *sem, int pshared, unsigned int value) |
| 114 | { |
| 115 | (*sem) = sem_alloc(value, pshared); |
| 116 | if ((*sem) == NULL) |
| 117 | return (-1); |
| 118 | return (0); |
| 119 | } |
| 120 | |
| 121 | int |
| 122 | _sem_destroy(sem_t *sem) |
| 123 | { |
| 124 | if (sem_check_validity(sem) != 0) |
| 125 | return (-1); |
| 126 | |
| 127 | (*sem)->magic = 0; |
| 128 | |
| 129 | switch ((*sem)->semid) { |
| 130 | case SEMID_LWP: |
| 131 | free(*sem); |
| 132 | break; |
| 133 | case SEMID_FORK: |
| 134 | /* memory is left intact */ |
| 135 | break; |
| 136 | } |
| 137 | return (0); |
| 138 | } |
| 139 | |
| 140 | int |
| 141 | _sem_getvalue(sem_t * __restrict sem, int * __restrict sval) |
| 142 | { |
| 143 | if (sem_check_validity(sem) != 0) |
| 144 | return (-1); |
| 145 | |
| 146 | *sval = (*sem)->count; |
| 147 | return (0); |
| 148 | } |
| 149 | |
| 150 | int |
| 151 | _sem_trywait(sem_t *sem) |
| 152 | { |
| 153 | int val; |
| 154 | |
| 155 | if (sem_check_validity(sem) != 0) |
| 156 | return (-1); |
| 157 | |
| 158 | while ((val = (*sem)->count) > 0) { |
| 159 | if (atomic_cmpset_int(&(*sem)->count, val, val - 1)) |
| 160 | return (0); |
| 161 | } |
| 162 | errno = EAGAIN; |
| 163 | return (-1); |
| 164 | } |
| 165 | |
| 166 | int |
| 167 | _sem_wait(sem_t *sem) |
| 168 | { |
| 169 | struct pthread *curthread; |
| 170 | int val, oldcancel, retval; |
| 171 | |
| 172 | if (sem_check_validity(sem) != 0) |
| 173 | return (-1); |
| 174 | |
| 175 | curthread = tls_get_curthread(); |
| 176 | _pthread_testcancel(); |
| 177 | do { |
| 178 | while ((val = (*sem)->count) > 0) { |
| 179 | if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1)) |
| 180 | return (0); |
| 181 | } |
| 182 | oldcancel = _thr_cancel_enter(curthread); |
| 183 | retval = _thr_umtx_wait(&(*sem)->count, 0, NULL, 0); |
| 184 | _thr_cancel_leave(curthread, oldcancel); |
| 185 | } while (retval == 0); |
| 186 | errno = retval; |
| 187 | return (-1); |
| 188 | } |
| 189 | |
| 190 | #if 0 |
| 191 | int |
| 192 | _sem_timedwait(sem_t * __restrict sem, struct timespec * __restrict abstime) |
| 193 | { |
| 194 | struct timespec ts, ts2; |
| 195 | struct pthread *curthread; |
| 196 | int val, oldcancel, retval; |
| 197 | |
| 198 | if (sem_check_validity(sem) != 0) |
| 199 | return (-1); |
| 200 | |
| 201 | curthread = tls_get_curthread(); |
| 202 | |
| 203 | /* |
| 204 | * The timeout argument is only supposed to |
| 205 | * be checked if the thread would have blocked. |
| 206 | */ |
| 207 | _pthread_testcancel(); |
| 208 | do { |
| 209 | while ((val = (*sem)->count) > 0) { |
| 210 | if (atomic_cmpset_acq_int(&(*sem)->count, val, val - 1)) |
| 211 | return (0); |
| 212 | } |
| 213 | if (abstime == NULL) { |
| 214 | errno = EINVAL; |
| 215 | return (-1); |
| 216 | } |
| 217 | clock_gettime(CLOCK_REALTIME, &ts); |
| 218 | TIMESPEC_SUB(&ts2, abstime, &ts); |
| 219 | oldcancel = _thr_cancel_enter(curthread); |
| 220 | retval = _thr_umtx_wait(&(*sem)->count, 0, &ts2, |
| 221 | CLOCK_REALTIME); |
| 222 | _thr_cancel_leave(curthread, oldcancel); |
| 223 | } while (retval == 0); |
| 224 | errno = retval; |
| 225 | return (-1); |
| 226 | } |
| 227 | #endif |
| 228 | |
| 229 | int |
| 230 | _sem_post(sem_t *sem) |
| 231 | { |
| 232 | int val; |
| 233 | |
| 234 | if (sem_check_validity(sem) != 0) |
| 235 | return (-1); |
| 236 | |
| 237 | /* |
| 238 | * sem_post() is required to be safe to call from within |
| 239 | * signal handlers, these code should work as that. |
| 240 | */ |
| 241 | do { |
| 242 | val = (*sem)->count; |
| 243 | } while (!atomic_cmpset_acq_int(&(*sem)->count, val, val + 1)); |
| 244 | _thr_umtx_wake(&(*sem)->count, val + 1); |
| 245 | return (0); |
| 246 | } |
| 247 | |
| 248 | sem_t * |
| 249 | _sem_open(const char *name, int oflag, ...) |
| 250 | { |
| 251 | errno = ENOSYS; |
| 252 | return (SEM_FAILED); |
| 253 | } |
| 254 | |
| 255 | int |
| 256 | _sem_close(sem_t *sem) |
| 257 | { |
| 258 | errno = ENOSYS; |
| 259 | return (-1); |
| 260 | } |
| 261 | |
| 262 | int |
| 263 | _sem_unlink(const char *name) |
| 264 | { |
| 265 | errno = ENOSYS; |
| 266 | return (-1); |
| 267 | } |
| 268 | |
| 269 | __strong_reference(_sem_destroy, sem_destroy); |
| 270 | __strong_reference(_sem_getvalue, sem_getvalue); |
| 271 | __strong_reference(_sem_init, sem_init); |
| 272 | __strong_reference(_sem_trywait, sem_trywait); |
| 273 | __strong_reference(_sem_wait, sem_wait); |
| 274 | #if 0 |
| 275 | __strong_reference(_sem_timedwait, sem_timedwait); |
| 276 | #endif |
| 277 | __strong_reference(_sem_post, sem_post); |
| 278 | __strong_reference(_sem_open, sem_open); |
| 279 | __strong_reference(_sem_close, sem_close); |
| 280 | __strong_reference(_sem_unlink, sem_unlink); |
| 281 | |