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FreeBSD/Linux Kernel Cross Reference
sys/kern/uipc_sem.c
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1 /*- 2 * Copyright (c) 2002 Alfred Perlstein <alfred@FreeBSD.org> 3 * Copyright (c) 2003-2005 SPARTA, Inc. 4 * Copyright (c) 2005 Robert N. M. Watson 5 * All rights reserved. 6 * 7 * This software was developed for the FreeBSD Project in part by Network 8 * Associates Laboratories, the Security Research Division of Network 9 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"), 10 * as part of the DARPA CHATS research program. 11 * 12 * Redistribution and use in source and binary forms, with or without 13 * modification, are permitted provided that the following conditions 14 * are met: 15 * 1. Redistributions of source code must retain the above copyright 16 * notice, this list of conditions and the following disclaimer. 17 * 2. Redistributions in binary form must reproduce the above copyright 18 * notice, this list of conditions and the following disclaimer in the 19 * documentation and/or other materials provided with the distribution. 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 24 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 31 * SUCH DAMAGE. 32 */ 33 34 #include <sys/cdefs.h> 35 __FBSDID("$FreeBSD: releng/8.0/sys/kern/uipc_sem.c 193511 2009-06-05 14:55:22Z rwatson $"); 36 37 #include "opt_posix.h" 38 39 #include <sys/param.h> 40 #include <sys/condvar.h> 41 #include <sys/fcntl.h> 42 #include <sys/file.h> 43 #include <sys/filedesc.h> 44 #include <sys/fnv_hash.h> 45 #include <sys/kernel.h> 46 #include <sys/ksem.h> 47 #include <sys/lock.h> 48 #include <sys/malloc.h> 49 #include <sys/module.h> 50 #include <sys/mutex.h> 51 #include <sys/priv.h> 52 #include <sys/proc.h> 53 #include <sys/posix4.h> 54 #include <sys/semaphore.h> 55 #include <sys/_semaphore.h> 56 #include <sys/stat.h> 57 #include <sys/syscall.h> 58 #include <sys/syscallsubr.h> 59 #include <sys/sysctl.h> 60 #include <sys/sysent.h> 61 #include <sys/sysproto.h> 62 #include <sys/systm.h> 63 #include <sys/sx.h> 64 #include <sys/vnode.h> 65 66 #include <security/mac/mac_framework.h> 67 68 /* 69 * TODO 70 * 71 * - Resource limits? 72 * - Update fstat(1) 73 * - Replace global sem_lock with mtx_pool locks? 74 * - Add a MAC check_create() hook for creating new named semaphores. 75 */ 76 77 #ifndef SEM_MAX 78 #define SEM_MAX 30 79 #endif 80 81 #ifdef SEM_DEBUG 82 #define DP(x) printf x 83 #else 84 #define DP(x) 85 #endif 86 87 struct ksem_mapping { 88 char *km_path; 89 Fnv32_t km_fnv; 90 struct ksem *km_ksem; 91 LIST_ENTRY(ksem_mapping) km_link; 92 }; 93 94 static MALLOC_DEFINE(M_KSEM, "ksem", "semaphore file descriptor"); 95 static LIST_HEAD(, ksem_mapping) *ksem_dictionary; 96 static struct sx ksem_dict_lock; 97 static struct mtx ksem_count_lock; 98 static struct mtx sem_lock; 99 static u_long ksem_hash; 100 static int ksem_dead; 101 102 #define KSEM_HASH(fnv) (&ksem_dictionary[(fnv) & ksem_hash]) 103 104 static int nsems = 0; 105 SYSCTL_DECL(_p1003_1b); 106 SYSCTL_INT(_p1003_1b, OID_AUTO, nsems, CTLFLAG_RD, &nsems, 0, 107 "Number of active kernel POSIX semaphores"); 108 109 static int kern_sem_wait(struct thread *td, semid_t id, int tryflag, 110 struct timespec *abstime); 111 static int ksem_access(struct ksem *ks, struct ucred *ucred); 112 static struct ksem *ksem_alloc(struct ucred *ucred, mode_t mode, 113 unsigned int value); 114 static int ksem_create(struct thread *td, const char *path, 115 semid_t *semidp, mode_t mode, unsigned int value, 116 int flags); 117 static void ksem_drop(struct ksem *ks); 118 static int ksem_get(struct thread *td, semid_t id, struct file **fpp); 119 static struct ksem *ksem_hold(struct ksem *ks); 120 static void ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks); 121 static struct ksem *ksem_lookup(char *path, Fnv32_t fnv); 122 static void ksem_module_destroy(void); 123 static int ksem_module_init(void); 124 static int ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred); 125 static int sem_modload(struct module *module, int cmd, void *arg); 126 127 static fo_rdwr_t ksem_read; 128 static fo_rdwr_t ksem_write; 129 static fo_truncate_t ksem_truncate; 130 static fo_ioctl_t ksem_ioctl; 131 static fo_poll_t ksem_poll; 132 static fo_kqfilter_t ksem_kqfilter; 133 static fo_stat_t ksem_stat; 134 static fo_close_t ksem_closef; 135 136 /* File descriptor operations. */ 137 static struct fileops ksem_ops = { 138 .fo_read = ksem_read, 139 .fo_write = ksem_write, 140 .fo_truncate = ksem_truncate, 141 .fo_ioctl = ksem_ioctl, 142 .fo_poll = ksem_poll, 143 .fo_kqfilter = ksem_kqfilter, 144 .fo_stat = ksem_stat, 145 .fo_close = ksem_closef, 146 .fo_flags = DFLAG_PASSABLE 147 }; 148 149 FEATURE(posix_sem, "POSIX semaphores"); 150 151 static int 152 ksem_read(struct file *fp, struct uio *uio, struct ucred *active_cred, 153 int flags, struct thread *td) 154 { 155 156 return (EOPNOTSUPP); 157 } 158 159 static int 160 ksem_write(struct file *fp, struct uio *uio, struct ucred *active_cred, 161 int flags, struct thread *td) 162 { 163 164 return (EOPNOTSUPP); 165 } 166 167 static int 168 ksem_truncate(struct file *fp, off_t length, struct ucred *active_cred, 169 struct thread *td) 170 { 171 172 return (EINVAL); 173 } 174 175 static int 176 ksem_ioctl(struct file *fp, u_long com, void *data, 177 struct ucred *active_cred, struct thread *td) 178 { 179 180 return (EOPNOTSUPP); 181 } 182 183 static int 184 ksem_poll(struct file *fp, int events, struct ucred *active_cred, 185 struct thread *td) 186 { 187 188 return (EOPNOTSUPP); 189 } 190 191 static int 192 ksem_kqfilter(struct file *fp, struct knote *kn) 193 { 194 195 return (EOPNOTSUPP); 196 } 197 198 static int 199 ksem_stat(struct file *fp, struct stat *sb, struct ucred *active_cred, 200 struct thread *td) 201 { 202 struct ksem *ks; 203 #ifdef MAC 204 int error; 205 #endif 206 207 ks = fp->f_data; 208 209 #ifdef MAC 210 error = mac_posixsem_check_stat(active_cred, fp->f_cred, ks); 211 if (error) 212 return (error); 213 #endif 214 215 /* 216 * Attempt to return sanish values for fstat() on a semaphore 217 * file descriptor. 218 */ 219 bzero(sb, sizeof(*sb)); 220 sb->st_mode = S_IFREG | ks->ks_mode; /* XXX */ 221 222 sb->st_atimespec = ks->ks_atime; 223 sb->st_ctimespec = ks->ks_ctime; 224 sb->st_mtimespec = ks->ks_mtime; 225 sb->st_birthtimespec = ks->ks_birthtime; 226 sb->st_uid = ks->ks_uid; 227 sb->st_gid = ks->ks_gid; 228 229 return (0); 230 } 231 232 static int 233 ksem_closef(struct file *fp, struct thread *td) 234 { 235 struct ksem *ks; 236 237 ks = fp->f_data; 238 fp->f_data = NULL; 239 ksem_drop(ks); 240 241 return (0); 242 } 243 244 /* 245 * ksem object management including creation and reference counting 246 * routines. 247 */ 248 static struct ksem * 249 ksem_alloc(struct ucred *ucred, mode_t mode, unsigned int value) 250 { 251 struct ksem *ks; 252 253 mtx_lock(&ksem_count_lock); 254 if (nsems == p31b_getcfg(CTL_P1003_1B_SEM_NSEMS_MAX) || ksem_dead) { 255 mtx_unlock(&ksem_count_lock); 256 return (NULL); 257 } 258 nsems++; 259 mtx_unlock(&ksem_count_lock); 260 ks = malloc(sizeof(*ks), M_KSEM, M_WAITOK | M_ZERO); 261 ks->ks_uid = ucred->cr_uid; 262 ks->ks_gid = ucred->cr_gid; 263 ks->ks_mode = mode; 264 ks->ks_value = value; 265 cv_init(&ks->ks_cv, "ksem"); 266 vfs_timestamp(&ks->ks_birthtime); 267 ks->ks_atime = ks->ks_mtime = ks->ks_ctime = ks->ks_birthtime; 268 refcount_init(&ks->ks_ref, 1); 269 #ifdef MAC 270 mac_posixsem_init(ks); 271 mac_posixsem_create(ucred, ks); 272 #endif 273 274 return (ks); 275 } 276 277 static struct ksem * 278 ksem_hold(struct ksem *ks) 279 { 280 281 refcount_acquire(&ks->ks_ref); 282 return (ks); 283 } 284 285 static void 286 ksem_drop(struct ksem *ks) 287 { 288 289 if (refcount_release(&ks->ks_ref)) { 290 #ifdef MAC 291 mac_posixsem_destroy(ks); 292 #endif 293 cv_destroy(&ks->ks_cv); 294 free(ks, M_KSEM); 295 mtx_lock(&ksem_count_lock); 296 nsems--; 297 mtx_unlock(&ksem_count_lock); 298 } 299 } 300 301 /* 302 * Determine if the credentials have sufficient permissions for read 303 * and write access. 304 */ 305 static int 306 ksem_access(struct ksem *ks, struct ucred *ucred) 307 { 308 int error; 309 310 error = vaccess(VREG, ks->ks_mode, ks->ks_uid, ks->ks_gid, 311 VREAD | VWRITE, ucred, NULL); 312 if (error) 313 error = priv_check_cred(ucred, PRIV_SEM_WRITE, 0); 314 return (error); 315 } 316 317 /* 318 * Dictionary management. We maintain an in-kernel dictionary to map 319 * paths to semaphore objects. We use the FNV hash on the path to 320 * store the mappings in a hash table. 321 */ 322 static struct ksem * 323 ksem_lookup(char *path, Fnv32_t fnv) 324 { 325 struct ksem_mapping *map; 326 327 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) { 328 if (map->km_fnv != fnv) 329 continue; 330 if (strcmp(map->km_path, path) == 0) 331 return (map->km_ksem); 332 } 333 334 return (NULL); 335 } 336 337 static void 338 ksem_insert(char *path, Fnv32_t fnv, struct ksem *ks) 339 { 340 struct ksem_mapping *map; 341 342 map = malloc(sizeof(struct ksem_mapping), M_KSEM, M_WAITOK); 343 map->km_path = path; 344 map->km_fnv = fnv; 345 map->km_ksem = ksem_hold(ks); 346 LIST_INSERT_HEAD(KSEM_HASH(fnv), map, km_link); 347 } 348 349 static int 350 ksem_remove(char *path, Fnv32_t fnv, struct ucred *ucred) 351 { 352 struct ksem_mapping *map; 353 int error; 354 355 LIST_FOREACH(map, KSEM_HASH(fnv), km_link) { 356 if (map->km_fnv != fnv) 357 continue; 358 if (strcmp(map->km_path, path) == 0) { 359 #ifdef MAC 360 error = mac_posixsem_check_unlink(ucred, map->km_ksem); 361 if (error) 362 return (error); 363 #endif 364 error = ksem_access(map->km_ksem, ucred); 365 if (error) 366 return (error); 367 LIST_REMOVE(map, km_link); 368 ksem_drop(map->km_ksem); 369 free(map->km_path, M_KSEM); 370 free(map, M_KSEM); 371 return (0); 372 } 373 } 374 375 return (ENOENT); 376 } 377 378 /* Other helper routines. */ 379 static int 380 ksem_create(struct thread *td, const char *name, semid_t *semidp, mode_t mode, 381 unsigned int value, int flags) 382 { 383 struct filedesc *fdp; 384 struct ksem *ks; 385 struct file *fp; 386 char *path; 387 semid_t semid; 388 Fnv32_t fnv; 389 int error, fd; 390 391 if (value > SEM_VALUE_MAX) 392 return (EINVAL); 393 394 fdp = td->td_proc->p_fd; 395 mode = (mode & ~fdp->fd_cmask) & ACCESSPERMS; 396 error = falloc(td, &fp, &fd); 397 if (error) { 398 if (name == NULL) 399 error = ENOSPC; 400 return (error); 401 } 402 403 /* 404 * Go ahead and copyout the file descriptor now. This is a bit 405 * premature, but it is a lot easier to handle errors as opposed 406 * to later when we've possibly created a new semaphore, etc. 407 */ 408 semid = fd; 409 error = copyout(&semid, semidp, sizeof(semid)); 410 if (error) { 411 fdclose(fdp, fp, fd, td); 412 fdrop(fp, td); 413 return (error); 414 } 415 416 if (name == NULL) { 417 /* Create an anonymous semaphore. */ 418 ks = ksem_alloc(td->td_ucred, mode, value); 419 if (ks == NULL) 420 error = ENOSPC; 421 else 422 ks->ks_flags |= KS_ANONYMOUS; 423 } else { 424 path = malloc(MAXPATHLEN, M_KSEM, M_WAITOK); 425 error = copyinstr(name, path, MAXPATHLEN, NULL); 426 427 /* Require paths to start with a '/' character. */ 428 if (error == 0 && path[0] != '/') 429 error = EINVAL; 430 if (error) { 431 fdclose(fdp, fp, fd, td); 432 fdrop(fp, td); 433 free(path, M_KSEM); 434 return (error); 435 } 436 437 fnv = fnv_32_str(path, FNV1_32_INIT); 438 sx_xlock(&ksem_dict_lock); 439 ks = ksem_lookup(path, fnv); 440 if (ks == NULL) { 441 /* Object does not exist, create it if requested. */ 442 if (flags & O_CREAT) { 443 ks = ksem_alloc(td->td_ucred, mode, value); 444 if (ks == NULL) 445 error = ENFILE; 446 else { 447 ksem_insert(path, fnv, ks); 448 path = NULL; 449 } 450 } else 451 error = ENOENT; 452 } else { 453 /* 454 * Object already exists, obtain a new 455 * reference if requested and permitted. 456 */ 457 if ((flags & (O_CREAT | O_EXCL)) == 458 (O_CREAT | O_EXCL)) 459 error = EEXIST; 460 else { 461 #ifdef MAC 462 error = mac_posixsem_check_open(td->td_ucred, 463 ks); 464 if (error == 0) 465 #endif 466 error = ksem_access(ks, td->td_ucred); 467 } 468 if (error == 0) 469 ksem_hold(ks); 470 #ifdef INVARIANTS 471 else 472 ks = NULL; 473 #endif 474 } 475 sx_xunlock(&ksem_dict_lock); 476 if (path) 477 free(path, M_KSEM); 478 } 479 480 if (error) { 481 KASSERT(ks == NULL, ("ksem_create error with a ksem")); 482 fdclose(fdp, fp, fd, td); 483 fdrop(fp, td); 484 return (error); 485 } 486 KASSERT(ks != NULL, ("ksem_create w/o a ksem")); 487 488 finit(fp, FREAD | FWRITE, DTYPE_SEM, ks, &ksem_ops); 489 490 FILEDESC_XLOCK(fdp); 491 if (fdp->fd_ofiles[fd] == fp) 492 fdp->fd_ofileflags[fd] |= UF_EXCLOSE; 493 FILEDESC_XUNLOCK(fdp); 494 fdrop(fp, td); 495 496 return (0); 497 } 498 499 static int 500 ksem_get(struct thread *td, semid_t id, struct file **fpp) 501 { 502 struct ksem *ks; 503 struct file *fp; 504 int error; 505 506 error = fget(td, id, &fp); 507 if (error) 508 return (EINVAL); 509 if (fp->f_type != DTYPE_SEM) { 510 fdrop(fp, td); 511 return (EINVAL); 512 } 513 ks = fp->f_data; 514 if (ks->ks_flags & KS_DEAD) { 515 fdrop(fp, td); 516 return (EINVAL); 517 } 518 *fpp = fp; 519 return (0); 520 } 521 522 /* System calls. */ 523 #ifndef _SYS_SYSPROTO_H_ 524 struct ksem_init_args { 525 unsigned int value; 526 semid_t *idp; 527 }; 528 #endif 529 int 530 ksem_init(struct thread *td, struct ksem_init_args *uap) 531 { 532 533 return (ksem_create(td, NULL, uap->idp, S_IRWXU | S_IRWXG, uap->value, 534 0)); 535 } 536 537 #ifndef _SYS_SYSPROTO_H_ 538 struct ksem_open_args { 539 char *name; 540 int oflag; 541 mode_t mode; 542 unsigned int value; 543 semid_t *idp; 544 }; 545 #endif 546 int 547 ksem_open(struct thread *td, struct ksem_open_args *uap) 548 { 549 550 DP((">>> ksem_open start, pid=%d\n", (int)td->td_proc->p_pid)); 551 552 if ((uap->oflag & ~(O_CREAT | O_EXCL)) != 0) 553 return (EINVAL); 554 return (ksem_create(td, uap->name, uap->idp, uap->mode, uap->value, 555 uap->oflag)); 556 } 557 558 #ifndef _SYS_SYSPROTO_H_ 559 struct ksem_unlink_args { 560 char *name; 561 }; 562 #endif 563 int 564 ksem_unlink(struct thread *td, struct ksem_unlink_args *uap) 565 { 566 char *path; 567 Fnv32_t fnv; 568 int error; 569 570 path = malloc(MAXPATHLEN, M_TEMP, M_WAITOK); 571 error = copyinstr(uap->name, path, MAXPATHLEN, NULL); 572 if (error) { 573 free(path, M_TEMP); 574 return (error); 575 } 576 577 fnv = fnv_32_str(path, FNV1_32_INIT); 578 sx_xlock(&ksem_dict_lock); 579 error = ksem_remove(path, fnv, td->td_ucred); 580 sx_xunlock(&ksem_dict_lock); 581 free(path, M_TEMP); 582 583 return (error); 584 } 585 586 #ifndef _SYS_SYSPROTO_H_ 587 struct ksem_close_args { 588 semid_t id; 589 }; 590 #endif 591 int 592 ksem_close(struct thread *td, struct ksem_close_args *uap) 593 { 594 struct ksem *ks; 595 struct file *fp; 596 int error; 597 598 error = ksem_get(td, uap->id, &fp); 599 if (error) 600 return (error); 601 ks = fp->f_data; 602 if (ks->ks_flags & KS_ANONYMOUS) { 603 fdrop(fp, td); 604 return (EINVAL); 605 } 606 error = kern_close(td, uap->id); 607 fdrop(fp, td); 608 return (error); 609 } 610 611 #ifndef _SYS_SYSPROTO_H_ 612 struct ksem_post_args { 613 semid_t id; 614 }; 615 #endif 616 int 617 ksem_post(struct thread *td, struct ksem_post_args *uap) 618 { 619 struct file *fp; 620 struct ksem *ks; 621 int error; 622 623 error = ksem_get(td, uap->id, &fp); 624 if (error) 625 return (error); 626 ks = fp->f_data; 627 628 mtx_lock(&sem_lock); 629 #ifdef MAC 630 error = mac_posixsem_check_post(td->td_ucred, fp->f_cred, ks); 631 if (error) 632 goto err; 633 #endif 634 if (ks->ks_value == SEM_VALUE_MAX) { 635 error = EOVERFLOW; 636 goto err; 637 } 638 ++ks->ks_value; 639 if (ks->ks_waiters > 0) 640 cv_signal(&ks->ks_cv); 641 error = 0; 642 vfs_timestamp(&ks->ks_ctime); 643 err: 644 mtx_unlock(&sem_lock); 645 fdrop(fp, td); 646 return (error); 647 } 648 649 #ifndef _SYS_SYSPROTO_H_ 650 struct ksem_wait_args { 651 semid_t id; 652 }; 653 #endif 654 int 655 ksem_wait(struct thread *td, struct ksem_wait_args *uap) 656 { 657 658 return (kern_sem_wait(td, uap->id, 0, NULL)); 659 } 660 661 #ifndef _SYS_SYSPROTO_H_ 662 struct ksem_timedwait_args { 663 semid_t id; 664 const struct timespec *abstime; 665 }; 666 #endif 667 int 668 ksem_timedwait(struct thread *td, struct ksem_timedwait_args *uap) 669 { 670 struct timespec abstime; 671 struct timespec *ts; 672 int error; 673 674 /* 675 * We allow a null timespec (wait forever). 676 */ 677 if (uap->abstime == NULL) 678 ts = NULL; 679 else { 680 error = copyin(uap->abstime, &abstime, sizeof(abstime)); 681 if (error != 0) 682 return (error); 683 if (abstime.tv_nsec >= 1000000000 || abstime.tv_nsec < 0) 684 return (EINVAL); 685 ts = &abstime; 686 } 687 return (kern_sem_wait(td, uap->id, 0, ts)); 688 } 689 690 #ifndef _SYS_SYSPROTO_H_ 691 struct ksem_trywait_args { 692 semid_t id; 693 }; 694 #endif 695 int 696 ksem_trywait(struct thread *td, struct ksem_trywait_args *uap) 697 { 698 699 return (kern_sem_wait(td, uap->id, 1, NULL)); 700 } 701 702 static int 703 kern_sem_wait(struct thread *td, semid_t id, int tryflag, 704 struct timespec *abstime) 705 { 706 struct timespec ts1, ts2; 707 struct timeval tv; 708 struct file *fp; 709 struct ksem *ks; 710 int error; 711 712 DP((">>> kern_sem_wait entered! pid=%d\n", (int)td->td_proc->p_pid)); 713 error = ksem_get(td, id, &fp); 714 if (error) 715 return (error); 716 ks = fp->f_data; 717 mtx_lock(&sem_lock); 718 DP((">>> kern_sem_wait critical section entered! pid=%d\n", 719 (int)td->td_proc->p_pid)); 720 #ifdef MAC 721 error = mac_posixsem_check_wait(td->td_ucred, fp->f_cred, ks); 722 if (error) { 723 DP(("kern_sem_wait mac failed\n")); 724 goto err; 725 } 726 #endif 727 DP(("kern_sem_wait value = %d, tryflag %d\n", ks->ks_value, tryflag)); 728 vfs_timestamp(&ks->ks_atime); 729 while (ks->ks_value == 0) { 730 ks->ks_waiters++; 731 if (tryflag != 0) 732 error = EAGAIN; 733 else if (abstime == NULL) 734 error = cv_wait_sig(&ks->ks_cv, &sem_lock); 735 else { 736 for (;;) { 737 ts1 = *abstime; 738 getnanotime(&ts2); 739 timespecsub(&ts1, &ts2); 740 TIMESPEC_TO_TIMEVAL(&tv, &ts1); 741 if (tv.tv_sec < 0) { 742 error = ETIMEDOUT; 743 break; 744 } 745 error = cv_timedwait_sig(&ks->ks_cv, 746 &sem_lock, tvtohz(&tv)); 747 if (error != EWOULDBLOCK) 748 break; 749 } 750 } 751 ks->ks_waiters--; 752 if (error) 753 goto err; 754 } 755 ks->ks_value--; 756 DP(("kern_sem_wait value post-decrement = %d\n", ks->ks_value)); 757 error = 0; 758 err: 759 mtx_unlock(&sem_lock); 760 fdrop(fp, td); 761 DP(("<<< kern_sem_wait leaving, pid=%d, error = %d\n", 762 (int)td->td_proc->p_pid, error)); 763 return (error); 764 } 765 766 #ifndef _SYS_SYSPROTO_H_ 767 struct ksem_getvalue_args { 768 semid_t id; 769 int *val; 770 }; 771 #endif 772 int 773 ksem_getvalue(struct thread *td, struct ksem_getvalue_args *uap) 774 { 775 struct file *fp; 776 struct ksem *ks; 777 int error, val; 778 779 error = ksem_get(td, uap->id, &fp); 780 if (error) 781 return (error); 782 ks = fp->f_data; 783 784 mtx_lock(&sem_lock); 785 #ifdef MAC 786 error = mac_posixsem_check_getvalue(td->td_ucred, fp->f_cred, ks); 787 if (error) { 788 mtx_unlock(&sem_lock); 789 fdrop(fp, td); 790 return (error); 791 } 792 #endif 793 val = ks->ks_value; 794 vfs_timestamp(&ks->ks_atime); 795 mtx_unlock(&sem_lock); 796 fdrop(fp, td); 797 error = copyout(&val, uap->val, sizeof(val)); 798 return (error); 799 } 800 801 #ifndef _SYS_SYSPROTO_H_ 802 struct ksem_destroy_args { 803 semid_t id; 804 }; 805 #endif 806 int 807 ksem_destroy(struct thread *td, struct ksem_destroy_args *uap) 808 { 809 struct file *fp; 810 struct ksem *ks; 811 int error; 812 813 error = ksem_get(td, uap->id, &fp); 814 if (error) 815 return (error); 816 ks = fp->f_data; 817 if (!(ks->ks_flags & KS_ANONYMOUS)) { 818 fdrop(fp, td); 819 return (EINVAL); 820 } 821 mtx_lock(&sem_lock); 822 if (ks->ks_waiters != 0) { 823 mtx_unlock(&sem_lock); 824 error = EBUSY; 825 goto err; 826 } 827 ks->ks_flags |= KS_DEAD; 828 mtx_unlock(&sem_lock); 829 830 error = kern_close(td, uap->id); 831 err: 832 fdrop(fp, td); 833 return (error); 834 } 835 836 #define SYSCALL_DATA(syscallname) \ 837 static int syscallname##_syscall = SYS_##syscallname; \ 838 static int syscallname##_registered; \ 839 static struct sysent syscallname##_old_sysent; \ 840 MAKE_SYSENT(syscallname); 841 842 #define SYSCALL_REGISTER(syscallname) do { \ 843 error = syscall_register(& syscallname##_syscall, \ 844 & syscallname##_sysent, & syscallname##_old_sysent); \ 845 if (error) \ 846 return (error); \ 847 syscallname##_registered = 1; \ 848 } while(0) 849 850 #define SYSCALL_DEREGISTER(syscallname) do { \ 851 if (syscallname##_registered) { \ 852 syscallname##_registered = 0; \ 853 syscall_deregister(& syscallname##_syscall, \ 854 & syscallname##_old_sysent); \ 855 } \ 856 } while(0) 857 858 SYSCALL_DATA(ksem_init); 859 SYSCALL_DATA(ksem_open); 860 SYSCALL_DATA(ksem_unlink); 861 SYSCALL_DATA(ksem_close); 862 SYSCALL_DATA(ksem_post); 863 SYSCALL_DATA(ksem_wait); 864 SYSCALL_DATA(ksem_timedwait); 865 SYSCALL_DATA(ksem_trywait); 866 SYSCALL_DATA(ksem_getvalue); 867 SYSCALL_DATA(ksem_destroy); 868 869 static int 870 ksem_module_init(void) 871 { 872 int error; 873 874 mtx_init(&sem_lock, "sem", NULL, MTX_DEF); 875 mtx_init(&ksem_count_lock, "ksem count", NULL, MTX_DEF); 876 sx_init(&ksem_dict_lock, "ksem dictionary"); 877 ksem_dictionary = hashinit(1024, M_KSEM, &ksem_hash); 878 p31b_setcfg(CTL_P1003_1B_SEM_NSEMS_MAX, SEM_MAX); 879 p31b_setcfg(CTL_P1003_1B_SEM_VALUE_MAX, SEM_VALUE_MAX); 880 881 SYSCALL_REGISTER(ksem_init); 882 SYSCALL_REGISTER(ksem_open); 883 SYSCALL_REGISTER(ksem_unlink); 884 SYSCALL_REGISTER(ksem_close); 885 SYSCALL_REGISTER(ksem_post); 886 SYSCALL_REGISTER(ksem_wait); 887 SYSCALL_REGISTER(ksem_timedwait); 888 SYSCALL_REGISTER(ksem_trywait); 889 SYSCALL_REGISTER(ksem_getvalue); 890 SYSCALL_REGISTER(ksem_destroy); 891 return (0); 892 } 893 894 static void 895 ksem_module_destroy(void) 896 { 897 898 SYSCALL_DEREGISTER(ksem_init); 899 SYSCALL_DEREGISTER(ksem_open); 900 SYSCALL_DEREGISTER(ksem_unlink); 901 SYSCALL_DEREGISTER(ksem_close); 902 SYSCALL_DEREGISTER(ksem_post); 903 SYSCALL_DEREGISTER(ksem_wait); 904 SYSCALL_DEREGISTER(ksem_timedwait); 905 SYSCALL_DEREGISTER(ksem_trywait); 906 SYSCALL_DEREGISTER(ksem_getvalue); 907 SYSCALL_DEREGISTER(ksem_destroy); 908 909 hashdestroy(ksem_dictionary, M_KSEM, ksem_hash); 910 sx_destroy(&ksem_dict_lock); 911 mtx_destroy(&ksem_count_lock); 912 mtx_destroy(&sem_lock); 913 } 914 915 static int 916 sem_modload(struct module *module, int cmd, void *arg) 917 { 918 int error = 0; 919 920 switch (cmd) { 921 case MOD_LOAD: 922 error = ksem_module_init(); 923 if (error) 924 ksem_module_destroy(); 925 break; 926 927 case MOD_UNLOAD: 928 mtx_lock(&ksem_count_lock); 929 if (nsems != 0) { 930 error = EOPNOTSUPP; 931 mtx_unlock(&ksem_count_lock); 932 break; 933 } 934 ksem_dead = 1; 935 mtx_unlock(&ksem_count_lock); 936 ksem_module_destroy(); 937 break; 938 939 case MOD_SHUTDOWN: 940 break; 941 default: 942 error = EINVAL; 943 break; 944 } 945 return (error); 946 } 947 948 static moduledata_t sem_mod = { 949 "sem", 950 &sem_modload, 951 NULL 952 }; 953 954 DECLARE_MODULE(sem, sem_mod, SI_SUB_SYSV_SEM, SI_ORDER_FIRST); 955 MODULE_VERSION(sem, 1);
Cache object: 25ae55f53285397a42420b9c687753dc
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