1 /* $NetBSD: uipc_sem.c,v 1.46 2016/06/10 23:24:33 christos Exp $ */ 2 3 /*- 4 * Copyright (c) 2011 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Mindaugas Rasiukevicius. 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 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /* 33 * Copyright (c) 2002 Alfred Perlstein <alfred@FreeBSD.org> 34 * All rights reserved. 35 * 36 * Redistribution and use in source and binary forms, with or without 37 * modification, are permitted provided that the following conditions 38 * are met: 39 * 1. Redistributions of source code must retain the above copyright 40 * notice, this list of conditions and the following disclaimer. 41 * 2. Redistributions in binary form must reproduce the above copyright 42 * notice, this list of conditions and the following disclaimer in the 43 * documentation and/or other materials provided with the distribution. 44 * 45 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 46 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 47 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 48 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 49 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 50 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 51 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 52 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 53 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 54 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 55 * SUCH DAMAGE. 56 */ 57 58 /* 59 * Implementation of POSIX semaphore. 60 */ 61 62 #include <sys/cdefs.h> 63 __KERNEL_RCSID(0, "$NetBSD: uipc_sem.c,v 1.46 2016/06/10 23:24:33 christos Exp $"); 64 65 #include <sys/param.h> 66 #include <sys/kernel.h> 67 68 #include <sys/atomic.h> 69 #include <sys/proc.h> 70 #include <sys/ksem.h> 71 #include <sys/syscall.h> 72 #include <sys/stat.h> 73 #include <sys/kmem.h> 74 #include <sys/fcntl.h> 75 #include <sys/file.h> 76 #include <sys/filedesc.h> 77 #include <sys/kauth.h> 78 #include <sys/module.h> 79 #include <sys/mount.h> 80 #include <sys/semaphore.h> 81 #include <sys/syscall.h> 82 #include <sys/syscallargs.h> 83 #include <sys/syscallvar.h> 84 #include <sys/sysctl.h> 85 86 MODULE(MODULE_CLASS_MISC, ksem, NULL); 87 88 #define SEM_MAX_NAMELEN 14 89 90 #define SEM_NSEMS_MAX 256 91 #define KS_UNLINKED 0x01 92 93 static kmutex_t ksem_lock __cacheline_aligned; 94 static LIST_HEAD(,ksem) ksem_head __cacheline_aligned; 95 static u_int nsems_total __cacheline_aligned; 96 static u_int nsems __cacheline_aligned; 97 98 static kauth_listener_t ksem_listener; 99 100 static int ksem_sysinit(void); 101 static int ksem_sysfini(bool); 102 static int ksem_modcmd(modcmd_t, void *); 103 static int ksem_close_fop(file_t *); 104 static int ksem_stat_fop(file_t *, struct stat *); 105 static int ksem_read_fop(file_t *, off_t *, struct uio *, 106 kauth_cred_t, int); 107 108 static const struct fileops semops = { 109 .fo_read = ksem_read_fop, 110 .fo_write = fbadop_write, 111 .fo_ioctl = fbadop_ioctl, 112 .fo_fcntl = fnullop_fcntl, 113 .fo_poll = fnullop_poll, 114 .fo_stat = ksem_stat_fop, 115 .fo_close = ksem_close_fop, 116 .fo_kqfilter = fnullop_kqfilter, 117 .fo_restart = fnullop_restart, 118 }; 119 120 static const struct syscall_package ksem_syscalls[] = { 121 { SYS__ksem_init, 0, (sy_call_t *)sys__ksem_init }, 122 { SYS__ksem_open, 0, (sy_call_t *)sys__ksem_open }, 123 { SYS__ksem_unlink, 0, (sy_call_t *)sys__ksem_unlink }, 124 { SYS__ksem_close, 0, (sy_call_t *)sys__ksem_close }, 125 { SYS__ksem_post, 0, (sy_call_t *)sys__ksem_post }, 126 { SYS__ksem_wait, 0, (sy_call_t *)sys__ksem_wait }, 127 { SYS__ksem_trywait, 0, (sy_call_t *)sys__ksem_trywait }, 128 { SYS__ksem_getvalue, 0, (sy_call_t *)sys__ksem_getvalue }, 129 { SYS__ksem_destroy, 0, (sy_call_t *)sys__ksem_destroy }, 130 { SYS__ksem_timedwait, 0, (sy_call_t *)sys__ksem_timedwait }, 131 { 0, 0, NULL }, 132 }; 133 134 struct sysctllog *ksem_clog; 135 int ksem_max; 136 137 static int 138 ksem_listener_cb(kauth_cred_t cred, kauth_action_t action, void *cookie, 139 void *arg0, void *arg1, void *arg2, void *arg3) 140 { 141 ksem_t *ks; 142 mode_t mode; 143 144 if (action != KAUTH_SYSTEM_SEMAPHORE) 145 return KAUTH_RESULT_DEFER; 146 147 ks = arg1; 148 mode = ks->ks_mode; 149 150 if ((kauth_cred_geteuid(cred) == ks->ks_uid && (mode & S_IWUSR) != 0) || 151 (kauth_cred_getegid(cred) == ks->ks_gid && (mode & S_IWGRP) != 0) || 152 (mode & S_IWOTH) != 0) 153 return KAUTH_RESULT_ALLOW; 154 155 return KAUTH_RESULT_DEFER; 156 } 157 158 static int 159 ksem_sysinit(void) 160 { 161 int error; 162 const struct sysctlnode *rnode; 163 164 mutex_init(&ksem_lock, MUTEX_DEFAULT, IPL_NONE); 165 LIST_INIT(&ksem_head); 166 nsems_total = 0; 167 nsems = 0; 168 169 error = syscall_establish(NULL, ksem_syscalls); 170 if (error) { 171 (void)ksem_sysfini(false); 172 } 173 174 ksem_listener = kauth_listen_scope(KAUTH_SCOPE_SYSTEM, 175 ksem_listener_cb, NULL); 176 177 /* Define module-specific sysctl tree */ 178 179 ksem_max = KSEM_MAX; 180 ksem_clog = NULL; 181 182 sysctl_createv(&ksem_clog, 0, NULL, &rnode, 183 CTLFLAG_PERMANENT, 184 CTLTYPE_NODE, "posix", 185 SYSCTL_DESCR("POSIX options"), 186 NULL, 0, NULL, 0, 187 CTL_KERN, CTL_CREATE, CTL_EOL); 188 sysctl_createv(&ksem_clog, 0, &rnode, NULL, 189 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 190 CTLTYPE_INT, "semmax", 191 SYSCTL_DESCR("Maximal number of semaphores"), 192 NULL, 0, &ksem_max, 0, 193 CTL_CREATE, CTL_EOL); 194 sysctl_createv(&ksem_clog, 0, &rnode, NULL, 195 CTLFLAG_PERMANENT | CTLFLAG_READONLY, 196 CTLTYPE_INT, "semcnt", 197 SYSCTL_DESCR("Current number of semaphores"), 198 NULL, 0, &nsems, 0, 199 CTL_CREATE, CTL_EOL); 200 201 return error; 202 } 203 204 static int 205 ksem_sysfini(bool interface) 206 { 207 int error; 208 209 if (interface) { 210 error = syscall_disestablish(NULL, ksem_syscalls); 211 if (error != 0) { 212 return error; 213 } 214 /* 215 * Make sure that no semaphores are in use. Note: semops 216 * must be unused at this point. 217 */ 218 if (nsems_total) { 219 error = syscall_establish(NULL, ksem_syscalls); 220 KASSERT(error == 0); 221 return EBUSY; 222 } 223 } 224 kauth_unlisten_scope(ksem_listener); 225 mutex_destroy(&ksem_lock); 226 sysctl_teardown(&ksem_clog); 227 return 0; 228 } 229 230 static int 231 ksem_modcmd(modcmd_t cmd, void *arg) 232 { 233 234 switch (cmd) { 235 case MODULE_CMD_INIT: 236 return ksem_sysinit(); 237 238 case MODULE_CMD_FINI: 239 return ksem_sysfini(true); 240 241 default: 242 return ENOTTY; 243 } 244 } 245 246 static ksem_t * 247 ksem_lookup(const char *name) 248 { 249 ksem_t *ks; 250 251 KASSERT(mutex_owned(&ksem_lock)); 252 253 LIST_FOREACH(ks, &ksem_head, ks_entry) { 254 if (strcmp(ks->ks_name, name) == 0) { 255 mutex_enter(&ks->ks_lock); 256 return ks; 257 } 258 } 259 return NULL; 260 } 261 262 static int 263 ksem_perm(lwp_t *l, ksem_t *ks) 264 { 265 kauth_cred_t uc = l->l_cred; 266 267 KASSERT(mutex_owned(&ks->ks_lock)); 268 269 if (kauth_authorize_system(uc, KAUTH_SYSTEM_SEMAPHORE, 0, ks, NULL, NULL) != 0) 270 return EACCES; 271 272 return 0; 273 } 274 275 /* 276 * ksem_get: get the semaphore from the descriptor. 277 * 278 * => locks the semaphore, if found. 279 * => holds a reference on the file descriptor. 280 */ 281 static int 282 ksem_get(int fd, ksem_t **ksret) 283 { 284 ksem_t *ks; 285 file_t *fp; 286 287 fp = fd_getfile(fd); 288 if (__predict_false(fp == NULL)) 289 return EINVAL; 290 if (__predict_false(fp->f_type != DTYPE_SEM)) { 291 fd_putfile(fd); 292 return EINVAL; 293 } 294 ks = fp->f_ksem; 295 mutex_enter(&ks->ks_lock); 296 297 *ksret = ks; 298 return 0; 299 } 300 301 /* 302 * ksem_create: allocate and setup a new semaphore structure. 303 */ 304 static int 305 ksem_create(lwp_t *l, const char *name, ksem_t **ksret, mode_t mode, u_int val) 306 { 307 ksem_t *ks; 308 kauth_cred_t uc; 309 char *kname; 310 size_t len; 311 312 /* Pre-check for the limit. */ 313 if (nsems >= ksem_max) { 314 return ENFILE; 315 } 316 317 if (val > SEM_VALUE_MAX) { 318 return EINVAL; 319 } 320 321 if (name != NULL) { 322 len = strlen(name); 323 if (len > SEM_MAX_NAMELEN) { 324 return ENAMETOOLONG; 325 } 326 /* Name must start with a '/' but not contain one. */ 327 if (*name != '/' || len < 2 || strchr(name + 1, '/') != NULL) { 328 return EINVAL; 329 } 330 kname = kmem_alloc(++len, KM_SLEEP); 331 strlcpy(kname, name, len); 332 } else { 333 kname = NULL; 334 len = 0; 335 } 336 337 if (atomic_inc_uint_nv(&l->l_proc->p_nsems) > SEM_NSEMS_MAX) { 338 atomic_dec_uint(&l->l_proc->p_nsems); 339 return -1; 340 } 341 342 ks = kmem_zalloc(sizeof(ksem_t), KM_SLEEP); 343 mutex_init(&ks->ks_lock, MUTEX_DEFAULT, IPL_NONE); 344 cv_init(&ks->ks_cv, "psem"); 345 ks->ks_name = kname; 346 ks->ks_namelen = len; 347 ks->ks_mode = mode; 348 ks->ks_value = val; 349 ks->ks_ref = 1; 350 351 uc = l->l_cred; 352 ks->ks_uid = kauth_cred_geteuid(uc); 353 ks->ks_gid = kauth_cred_getegid(uc); 354 355 atomic_inc_uint(&nsems_total); 356 *ksret = ks; 357 return 0; 358 } 359 360 static void 361 ksem_free(ksem_t *ks) 362 { 363 364 KASSERT(!cv_has_waiters(&ks->ks_cv)); 365 366 if (ks->ks_name) { 367 KASSERT(ks->ks_namelen > 0); 368 kmem_free(ks->ks_name, ks->ks_namelen); 369 } 370 mutex_destroy(&ks->ks_lock); 371 cv_destroy(&ks->ks_cv); 372 kmem_free(ks, sizeof(ksem_t)); 373 374 atomic_dec_uint(&nsems_total); 375 atomic_dec_uint(&curproc->p_nsems); 376 } 377 378 int 379 sys__ksem_init(struct lwp *l, const struct sys__ksem_init_args *uap, 380 register_t *retval) 381 { 382 /* { 383 unsigned int value; 384 intptr_t *idp; 385 } */ 386 387 return do_ksem_init(l, SCARG(uap, value), SCARG(uap, idp), copyout); 388 } 389 390 int 391 do_ksem_init(lwp_t *l, u_int val, intptr_t *idp, copyout_t docopyout) 392 { 393 proc_t *p = l->l_proc; 394 ksem_t *ks; 395 file_t *fp; 396 intptr_t id; 397 int fd, error; 398 399 error = fd_allocfile(&fp, &fd); 400 if (error) { 401 return error; 402 } 403 fp->f_type = DTYPE_SEM; 404 fp->f_flag = FREAD | FWRITE; 405 fp->f_ops = &semops; 406 407 id = (intptr_t)fd; 408 error = (*docopyout)(&id, idp, sizeof(*idp)); 409 if (error) { 410 fd_abort(p, fp, fd); 411 return error; 412 } 413 414 /* Note the mode does not matter for anonymous semaphores. */ 415 error = ksem_create(l, NULL, &ks, 0, val); 416 if (error) { 417 fd_abort(p, fp, fd); 418 return error; 419 } 420 fp->f_ksem = ks; 421 fd_affix(p, fp, fd); 422 return error; 423 } 424 425 int 426 sys__ksem_open(struct lwp *l, const struct sys__ksem_open_args *uap, 427 register_t *retval) 428 { 429 /* { 430 const char *name; 431 int oflag; 432 mode_t mode; 433 unsigned int value; 434 intptr_t *idp; 435 } */ 436 437 return do_ksem_open(l, SCARG(uap, name), SCARG(uap, oflag), 438 SCARG(uap, mode), SCARG(uap, value), SCARG(uap, idp), copyout); 439 } 440 441 int 442 do_ksem_open(struct lwp *l, const char *semname, int oflag, mode_t mode, 443 unsigned int value, intptr_t *idp, copyout_t docopyout) 444 { 445 char name[SEM_MAX_NAMELEN + 1]; 446 proc_t *p = l->l_proc; 447 ksem_t *ksnew = NULL, *ks; 448 file_t *fp; 449 intptr_t id; 450 int fd, error; 451 452 error = copyinstr(semname, name, sizeof(name), NULL); 453 if (error) { 454 return error; 455 } 456 error = fd_allocfile(&fp, &fd); 457 if (error) { 458 return error; 459 } 460 fp->f_type = DTYPE_SEM; 461 fp->f_flag = FREAD | FWRITE; 462 fp->f_ops = &semops; 463 464 /* 465 * The ID (file descriptor number) can be stored early. 466 * Note that zero is a special value for libpthread. 467 */ 468 id = (intptr_t)fd; 469 error = (*docopyout)(&id, idp, sizeof(*idp)); 470 if (error) { 471 goto err; 472 } 473 474 if (oflag & O_CREAT) { 475 /* Create a new semaphore. */ 476 error = ksem_create(l, name, &ksnew, mode, value); 477 if (error) { 478 goto err; 479 } 480 KASSERT(ksnew != NULL); 481 } 482 483 /* Lookup for a semaphore with such name. */ 484 mutex_enter(&ksem_lock); 485 ks = ksem_lookup(name); 486 if (ks) { 487 KASSERT(mutex_owned(&ks->ks_lock)); 488 mutex_exit(&ksem_lock); 489 490 /* Check for exclusive create. */ 491 if (oflag & O_EXCL) { 492 mutex_exit(&ks->ks_lock); 493 error = EEXIST; 494 goto err; 495 } 496 /* 497 * Verify permissions. If we can access it, 498 * add the reference of this thread. 499 */ 500 error = ksem_perm(l, ks); 501 if (error == 0) { 502 ks->ks_ref++; 503 } 504 mutex_exit(&ks->ks_lock); 505 if (error) { 506 goto err; 507 } 508 } else { 509 /* Fail if not found and not creating. */ 510 if ((oflag & O_CREAT) == 0) { 511 mutex_exit(&ksem_lock); 512 KASSERT(ksnew == NULL); 513 error = ENOENT; 514 goto err; 515 } 516 517 /* Check for the limit locked. */ 518 if (nsems >= ksem_max) { 519 mutex_exit(&ksem_lock); 520 error = ENFILE; 521 goto err; 522 } 523 524 /* 525 * Finally, insert semaphore into the list. 526 * Note: it already has the initial reference. 527 */ 528 ks = ksnew; 529 LIST_INSERT_HEAD(&ksem_head, ks, ks_entry); 530 nsems++; 531 mutex_exit(&ksem_lock); 532 533 ksnew = NULL; 534 } 535 KASSERT(ks != NULL); 536 fp->f_ksem = ks; 537 fd_affix(p, fp, fd); 538 err: 539 if (error) { 540 fd_abort(p, fp, fd); 541 } 542 if (ksnew) { 543 ksem_free(ksnew); 544 } 545 return error; 546 } 547 548 int 549 sys__ksem_close(struct lwp *l, const struct sys__ksem_close_args *uap, 550 register_t *retval) 551 { 552 /* { 553 intptr_t id; 554 } */ 555 int fd = (int)SCARG(uap, id); 556 557 if (fd_getfile(fd) == NULL) { 558 return EBADF; 559 } 560 return fd_close(fd); 561 } 562 563 static int 564 ksem_read_fop(file_t *fp, off_t *offset, struct uio *uio, kauth_cred_t cred, 565 int flags) 566 { 567 size_t len; 568 char *name; 569 ksem_t *ks = fp->f_ksem; 570 571 mutex_enter(&ks->ks_lock); 572 len = ks->ks_namelen; 573 name = ks->ks_name; 574 mutex_exit(&ks->ks_lock); 575 if (name == NULL || len == 0) 576 return 0; 577 return uiomove(name, len, uio); 578 } 579 580 static int 581 ksem_stat_fop(file_t *fp, struct stat *ub) 582 { 583 ksem_t *ks = fp->f_ksem; 584 585 mutex_enter(&ks->ks_lock); 586 587 memset(ub, 0, sizeof(*ub)); 588 589 ub->st_mode = ks->ks_mode | ((ks->ks_name && ks->ks_namelen) 590 ? _S_IFLNK : _S_IFREG); 591 ub->st_uid = ks->ks_uid; 592 ub->st_gid = ks->ks_gid; 593 ub->st_size = ks->ks_value; 594 ub->st_blocks = (ub->st_size) ? 1 : 0; 595 ub->st_nlink = ks->ks_ref; 596 ub->st_blksize = 4096; 597 598 nanotime(&ub->st_atimespec); 599 ub->st_mtimespec = ub->st_ctimespec = ub->st_birthtimespec = 600 ub->st_atimespec; 601 602 /* 603 * Left as 0: st_dev, st_ino, st_rdev, st_flags, st_gen. 604 * XXX (st_dev, st_ino) should be unique. 605 */ 606 mutex_exit(&ks->ks_lock); 607 return 0; 608 } 609 610 static int 611 ksem_close_fop(file_t *fp) 612 { 613 ksem_t *ks = fp->f_ksem; 614 bool destroy = false; 615 616 mutex_enter(&ks->ks_lock); 617 KASSERT(ks->ks_ref > 0); 618 if (--ks->ks_ref == 0) { 619 /* 620 * Destroy if the last reference and semaphore is unnamed, 621 * or unlinked (for named semaphore). 622 */ 623 destroy = (ks->ks_flags & KS_UNLINKED) || (ks->ks_name == NULL); 624 } 625 mutex_exit(&ks->ks_lock); 626 627 if (destroy) { 628 ksem_free(ks); 629 } 630 return 0; 631 } 632 633 int 634 sys__ksem_unlink(struct lwp *l, const struct sys__ksem_unlink_args *uap, 635 register_t *retval) 636 { 637 /* { 638 const char *name; 639 } */ 640 char name[SEM_MAX_NAMELEN + 1]; 641 ksem_t *ks; 642 u_int refcnt; 643 int error; 644 645 error = copyinstr(SCARG(uap, name), name, sizeof(name), NULL); 646 if (error) 647 return error; 648 649 mutex_enter(&ksem_lock); 650 ks = ksem_lookup(name); 651 if (ks == NULL) { 652 mutex_exit(&ksem_lock); 653 return ENOENT; 654 } 655 KASSERT(mutex_owned(&ks->ks_lock)); 656 657 /* Verify permissions. */ 658 error = ksem_perm(l, ks); 659 if (error) { 660 mutex_exit(&ks->ks_lock); 661 mutex_exit(&ksem_lock); 662 return error; 663 } 664 665 /* Remove from the global list. */ 666 LIST_REMOVE(ks, ks_entry); 667 nsems--; 668 mutex_exit(&ksem_lock); 669 670 refcnt = ks->ks_ref; 671 if (refcnt) { 672 /* Mark as unlinked, if there are references. */ 673 ks->ks_flags |= KS_UNLINKED; 674 } 675 mutex_exit(&ks->ks_lock); 676 677 if (refcnt == 0) { 678 ksem_free(ks); 679 } 680 return 0; 681 } 682 683 int 684 sys__ksem_post(struct lwp *l, const struct sys__ksem_post_args *uap, 685 register_t *retval) 686 { 687 /* { 688 intptr_t id; 689 } */ 690 int fd = (int)SCARG(uap, id), error; 691 ksem_t *ks; 692 693 error = ksem_get(fd, &ks); 694 if (error) { 695 return error; 696 } 697 KASSERT(mutex_owned(&ks->ks_lock)); 698 if (ks->ks_value == SEM_VALUE_MAX) { 699 error = EOVERFLOW; 700 goto out; 701 } 702 ks->ks_value++; 703 if (ks->ks_waiters) { 704 cv_broadcast(&ks->ks_cv); 705 } 706 out: 707 mutex_exit(&ks->ks_lock); 708 fd_putfile(fd); 709 return error; 710 } 711 712 int 713 do_ksem_wait(lwp_t *l, intptr_t id, bool try_p, struct timespec *abstime) 714 { 715 int fd = (int)id, error, timeo; 716 ksem_t *ks; 717 718 error = ksem_get(fd, &ks); 719 if (error) { 720 return error; 721 } 722 KASSERT(mutex_owned(&ks->ks_lock)); 723 while (ks->ks_value == 0) { 724 ks->ks_waiters++; 725 if (!try_p && abstime != NULL) { 726 error = ts2timo(CLOCK_REALTIME, TIMER_ABSTIME, abstime, 727 &timeo, NULL); 728 if (error != 0) 729 goto out; 730 } else { 731 timeo = 0; 732 } 733 error = try_p ? EAGAIN : cv_timedwait_sig(&ks->ks_cv, 734 &ks->ks_lock, timeo); 735 ks->ks_waiters--; 736 if (error) 737 goto out; 738 } 739 ks->ks_value--; 740 out: 741 mutex_exit(&ks->ks_lock); 742 fd_putfile(fd); 743 return error; 744 } 745 746 int 747 sys__ksem_wait(struct lwp *l, const struct sys__ksem_wait_args *uap, 748 register_t *retval) 749 { 750 /* { 751 intptr_t id; 752 } */ 753 754 return do_ksem_wait(l, SCARG(uap, id), false, NULL); 755 } 756 757 int 758 sys__ksem_timedwait(struct lwp *l, const struct sys__ksem_timedwait_args *uap, 759 register_t *retval) 760 { 761 /* { 762 intptr_t id; 763 const struct timespec *abstime; 764 } */ 765 struct timespec ts; 766 int error; 767 768 error = copyin(SCARG(uap, abstime), &ts, sizeof(ts)); 769 if (error != 0) 770 return error; 771 772 if (ts.tv_sec < 0 || ts.tv_nsec < 0 || ts.tv_nsec >= 1000000000) 773 return EINVAL; 774 775 error = do_ksem_wait(l, SCARG(uap, id), false, &ts); 776 if (error == EWOULDBLOCK) 777 error = ETIMEDOUT; 778 return error; 779 } 780 781 int 782 sys__ksem_trywait(struct lwp *l, const struct sys__ksem_trywait_args *uap, 783 register_t *retval) 784 { 785 /* { 786 intptr_t id; 787 } */ 788 789 return do_ksem_wait(l, SCARG(uap, id), true, NULL); 790 } 791 792 int 793 sys__ksem_getvalue(struct lwp *l, const struct sys__ksem_getvalue_args *uap, 794 register_t *retval) 795 { 796 /* { 797 intptr_t id; 798 unsigned int *value; 799 } */ 800 int fd = (int)SCARG(uap, id), error; 801 ksem_t *ks; 802 unsigned int val; 803 804 error = ksem_get(fd, &ks); 805 if (error) { 806 return error; 807 } 808 KASSERT(mutex_owned(&ks->ks_lock)); 809 val = ks->ks_value; 810 mutex_exit(&ks->ks_lock); 811 fd_putfile(fd); 812 813 return copyout(&val, SCARG(uap, value), sizeof(val)); 814 } 815 816 int 817 sys__ksem_destroy(struct lwp *l, const struct sys__ksem_destroy_args *uap, 818 register_t *retval) 819 { 820 /* { 821 intptr_t id; 822 } */ 823 int fd = (int)SCARG(uap, id), error; 824 ksem_t *ks; 825 826 error = ksem_get(fd, &ks); 827 if (error) { 828 return error; 829 } 830 KASSERT(mutex_owned(&ks->ks_lock)); 831 832 /* Operation is only for unnamed semaphores. */ 833 if (ks->ks_name != NULL) { 834 error = EINVAL; 835 goto out; 836 } 837 /* Cannot destroy if there are waiters. */ 838 if (ks->ks_waiters) { 839 error = EBUSY; 840 goto out; 841 } 842 out: 843 mutex_exit(&ks->ks_lock); 844 if (error) { 845 fd_putfile(fd); 846 return error; 847 } 848 return fd_close(fd); 849 } 850