uipc_sem.c revision 1.8.2.1
1 /* $NetBSD: uipc_sem.c,v 1.8.2.1 2003/07/02 15:26:44 darrenr Exp $ */ 2 3 /*- 4 * Copyright (c) 2003 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of Wasabi Systems, Inc. 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 * 3. All advertising materials mentioning features or use of this software 19 * must display the following acknowledgement: 20 * This product includes software developed by the NetBSD 21 * Foundation, Inc. and its contributors. 22 * 4. Neither the name of The NetBSD Foundation nor the names of its 23 * contributors may be used to endorse or promote products derived 24 * from this software without specific prior written permission. 25 * 26 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 27 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 28 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 29 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 30 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 31 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 32 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 33 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 34 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 35 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 36 * POSSIBILITY OF SUCH DAMAGE. 37 */ 38 39 /* 40 * Copyright (c) 2002 Alfred Perlstein <alfred (at) FreeBSD.org> 41 * All rights reserved. 42 * 43 * Redistribution and use in source and binary forms, with or without 44 * modification, are permitted provided that the following conditions 45 * are met: 46 * 1. Redistributions of source code must retain the above copyright 47 * notice, this list of conditions and the following disclaimer. 48 * 2. Redistributions in binary form must reproduce the above copyright 49 * notice, this list of conditions and the following disclaimer in the 50 * documentation and/or other materials provided with the distribution. 51 * 52 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 53 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 54 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 55 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 56 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 57 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 58 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 59 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 60 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 61 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 62 * SUCH DAMAGE. 63 */ 64 65 #include "opt_posix.h" 66 67 #include <sys/param.h> 68 #include <sys/systm.h> 69 #include <sys/kernel.h> 70 #include <sys/proc.h> 71 #include <sys/lock.h> 72 #include <sys/ksem.h> 73 #include <sys/sa.h> 74 #include <sys/syscall.h> 75 #include <sys/stat.h> 76 #include <sys/malloc.h> 77 #include <sys/fcntl.h> 78 79 #include <sys/mount.h> 80 81 #include <sys/syscallargs.h> 82 83 #ifndef SEM_MAX 84 #define SEM_MAX 30 85 #endif 86 87 #define SEM_MAX_NAMELEN 14 88 #define SEM_VALUE_MAX (~0U) 89 90 #define SEM_TO_ID(x) ((intptr_t)(x)) 91 92 MALLOC_DEFINE(M_SEM, "p1003_1b_sem", "p1003_1b semaphores"); 93 94 /* 95 * Note: to read the ks_name member, you need either the ks_interlock 96 * or the ksem_slock. To write the ks_name member, you need both. Make 97 * sure the order is ksem_slock -> ks_interlock. 98 */ 99 struct ksem { 100 LIST_ENTRY(ksem) ks_entry; /* global list entry */ 101 struct simplelock ks_interlock; /* lock on this ksem */ 102 char *ks_name; /* if named, this is the name */ 103 unsigned int ks_ref; /* number of references */ 104 mode_t ks_mode; /* protection bits */ 105 uid_t ks_uid; /* creator uid */ 106 gid_t ks_gid; /* creator gid */ 107 unsigned int ks_value; /* current value */ 108 unsigned int ks_waiters; /* number of waiters */ 109 }; 110 111 struct ksem_ref { 112 LIST_ENTRY(ksem_ref) ksr_list; 113 struct ksem *ksr_ksem; 114 }; 115 116 struct ksem_proc { 117 struct lock kp_lock; 118 LIST_HEAD(, ksem_ref) kp_ksems; 119 }; 120 121 /* 122 * ksem_slock protects ksem_head and nsems. Only named semaphores go 123 * onto ksem_head. 124 */ 125 static struct simplelock ksem_slock; 126 static LIST_HEAD(, ksem) ksem_head = LIST_HEAD_INITIALIZER(&ksem_head); 127 static int nsems = 0; 128 129 static void 130 ksem_free(struct ksem *ks) 131 { 132 133 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 134 /* 135 * If the ksem is anonymous (or has been unlinked), then 136 * this is the end if its life. 137 */ 138 if (ks->ks_name == NULL) { 139 simple_unlock(&ks->ks_interlock); 140 free(ks, M_SEM); 141 142 simple_lock(&ksem_slock); 143 nsems--; 144 simple_unlock(&ksem_slock); 145 return; 146 } 147 simple_unlock(&ks->ks_interlock); 148 } 149 150 static __inline void 151 ksem_addref(struct ksem *ks) 152 { 153 154 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 155 ks->ks_ref++; 156 KASSERT(ks->ks_ref != 0); /* XXX KDASSERT */ 157 } 158 159 static __inline void 160 ksem_delref(struct ksem *ks) 161 { 162 163 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 164 KASSERT(ks->ks_ref != 0); /* XXX KDASSERT */ 165 if (--ks->ks_ref == 0) { 166 ksem_free(ks); 167 return; 168 } 169 simple_unlock(&ks->ks_interlock); 170 } 171 172 static struct ksem_proc * 173 ksem_proc_alloc(void) 174 { 175 struct ksem_proc *kp; 176 177 kp = malloc(sizeof(*kp), M_SEM, M_WAITOK); 178 lockinit(&kp->kp_lock, PWAIT, "ksproc", 0, 0); 179 LIST_INIT(&kp->kp_ksems); 180 181 return (kp); 182 } 183 184 static void 185 ksem_add_proc(struct proc *p, struct ksem *ks) 186 { 187 struct ksem_proc *kp; 188 struct ksem_ref *ksr; 189 190 if (p->p_ksems == NULL) { 191 kp = ksem_proc_alloc(); 192 p->p_ksems = kp; 193 } else 194 kp = p->p_ksems; 195 196 ksr = malloc(sizeof(*ksr), M_SEM, M_WAITOK); 197 ksr->ksr_ksem = ks; 198 199 lockmgr(&kp->kp_lock, LK_EXCLUSIVE, NULL); 200 LIST_INSERT_HEAD(&kp->kp_ksems, ksr, ksr_list); 201 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 202 } 203 204 /* We MUST have a write lock on the ksem_proc list! */ 205 static struct ksem_ref * 206 ksem_drop_proc(struct ksem_proc *kp, struct ksem *ks) 207 { 208 struct ksem_ref *ksr; 209 210 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 211 LIST_FOREACH(ksr, &kp->kp_ksems, ksr_list) { 212 if (ksr->ksr_ksem == ks) { 213 ksem_delref(ks); 214 LIST_REMOVE(ksr, ksr_list); 215 return (ksr); 216 } 217 } 218 #ifdef DIAGNOSTIC 219 panic("ksem_drop_proc: ksem_proc %p ksem %p", kp, ks); 220 #endif 221 return (NULL); 222 } 223 224 static int 225 ksem_perm(struct proc *p, struct ksem *ks) 226 { 227 struct ucred *uc; 228 229 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 230 uc = p->p_ucred; 231 if ((uc->cr_uid == ks->ks_uid && (ks->ks_mode & S_IWUSR) != 0) || 232 (uc->cr_gid == ks->ks_gid && (ks->ks_mode & S_IWGRP) != 0) || 233 (ks->ks_mode & S_IWOTH) != 0 || suser(uc, &p->p_acflag) == 0) 234 return (0); 235 return (EPERM); 236 } 237 238 static struct ksem * 239 ksem_lookup_byname(const char *name) 240 { 241 struct ksem *ks; 242 243 LOCK_ASSERT(simple_lock_held(&ksem_slock)); 244 LIST_FOREACH(ks, &ksem_head, ks_entry) { 245 if (strcmp(ks->ks_name, name) == 0) { 246 simple_lock(&ks->ks_interlock); 247 return (ks); 248 } 249 } 250 return (NULL); 251 } 252 253 static int 254 ksem_create(struct proc *p, const char *name, struct ksem **ksret, 255 mode_t mode, unsigned int value) 256 { 257 struct ksem *ret; 258 struct ucred *uc; 259 size_t len; 260 261 uc = p->p_ucred; 262 if (value > SEM_VALUE_MAX) 263 return (EINVAL); 264 ret = malloc(sizeof(*ret), M_SEM, M_WAITOK | M_ZERO); 265 if (name != NULL) { 266 len = strlen(name); 267 if (len > SEM_MAX_NAMELEN) { 268 free(ret, M_SEM); 269 return (ENAMETOOLONG); 270 } 271 /* name must start with a '/' but not contain one. */ 272 if (*name != '/' || len < 2 || strchr(name + 1, '/') != NULL) { 273 free(ret, M_SEM); 274 return (EINVAL); 275 } 276 ret->ks_name = malloc(len + 1, M_SEM, M_WAITOK); 277 strlcpy(ret->ks_name, name, len + 1); 278 } else 279 ret->ks_name = NULL; 280 ret->ks_mode = mode; 281 ret->ks_value = value; 282 ret->ks_ref = 1; 283 ret->ks_waiters = 0; 284 ret->ks_uid = uc->cr_uid; 285 ret->ks_gid = uc->cr_gid; 286 simple_lock_init(&ret->ks_interlock); 287 288 simple_lock(&ksem_slock); 289 if (nsems >= SEM_MAX) { 290 simple_unlock(&ksem_slock); 291 if (ret->ks_name != NULL) 292 free(ret->ks_name, M_SEM); 293 free(ret, M_SEM); 294 return (ENFILE); 295 } 296 nsems++; 297 simple_unlock(&ksem_slock); 298 299 *ksret = ret; 300 return (0); 301 } 302 303 int 304 sys__ksem_init(struct lwp *l, void *v, register_t *retval) 305 { 306 struct sys__ksem_init_args /* { 307 unsigned int value; 308 semid_t *idp; 309 } */ *uap = v; 310 struct ksem *ks; 311 semid_t id; 312 int error; 313 314 /* Note the mode does not matter for anonymous semaphores. */ 315 error = ksem_create(l->l_proc, NULL, &ks, 0, SCARG(uap, value)); 316 if (error) 317 return (error); 318 id = SEM_TO_ID(ks); 319 error = copyout(&id, SCARG(uap, idp), sizeof(id)); 320 if (error) { 321 simple_lock(&ks->ks_interlock); 322 ksem_delref(ks); 323 return (error); 324 } 325 326 ksem_add_proc(l->l_proc, ks); 327 328 return (0); 329 } 330 331 int 332 sys__ksem_open(struct lwp *l, void *v, register_t *retval) 333 { 334 struct sys__ksem_open_args /* { 335 const char *name; 336 int oflag; 337 mode_t mode; 338 unsigned int value; 339 semid_t *idp; 340 } */ *uap = v; 341 char name[SEM_MAX_NAMELEN + 1]; 342 size_t done; 343 int error; 344 struct ksem *ksnew, *ks; 345 semid_t id; 346 347 error = copyinstr(SCARG(uap, name), name, sizeof(name), &done); 348 if (error) 349 return (error); 350 351 ksnew = NULL; 352 simple_lock(&ksem_slock); 353 ks = ksem_lookup_byname(name); 354 355 /* Found one? */ 356 if (ks != NULL) { 357 /* Check for exclusive create. */ 358 if (SCARG(uap, oflag) & O_EXCL) { 359 simple_unlock(&ks->ks_interlock); 360 simple_unlock(&ksem_slock); 361 return (EEXIST); 362 } 363 found_one: 364 /* 365 * Verify permissions. If we can access it, add 366 * this process's reference. 367 */ 368 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 369 error = ksem_perm(l->l_proc, ks); 370 if (error == 0) 371 ksem_addref(ks); 372 simple_unlock(&ks->ks_interlock); 373 simple_unlock(&ksem_slock); 374 if (error) 375 return (error); 376 377 id = SEM_TO_ID(ks); 378 error = copyout(&id, SCARG(uap, idp), sizeof(id)); 379 if (error) { 380 simple_lock(&ks->ks_interlock); 381 ksem_delref(ks); 382 return (error); 383 } 384 385 ksem_add_proc(l->l_proc, ks); 386 387 return (0); 388 } 389 390 /* 391 * didn't ask for creation? error. 392 */ 393 if ((SCARG(uap, oflag) & O_CREAT) == 0) { 394 simple_unlock(&ksem_slock); 395 return (ENOENT); 396 } 397 398 /* 399 * We may block during creation, so drop the lock. 400 */ 401 simple_unlock(&ksem_slock); 402 error = ksem_create(l->l_proc, name, &ksnew, SCARG(uap, mode), 403 SCARG(uap, value)); 404 if (error != 0) 405 return (error); 406 407 id = SEM_TO_ID(ksnew); 408 error = copyout(&id, SCARG(uap, idp), sizeof(id)); 409 if (error) { 410 free(ksnew->ks_name, M_SEM); 411 ksnew->ks_name = NULL; 412 413 simple_lock(&ksnew->ks_interlock); 414 ksem_delref(ksnew); 415 return (error); 416 } 417 418 /* 419 * We need to make sure we haven't lost a race while 420 * allocating during creation. 421 */ 422 simple_lock(&ksem_slock); 423 if ((ks = ksem_lookup_byname(name)) != NULL) { 424 if (SCARG(uap, oflag) & O_EXCL) { 425 simple_unlock(&ks->ks_interlock); 426 simple_unlock(&ksem_slock); 427 428 free(ksnew->ks_name, M_SEM); 429 ksnew->ks_name = NULL; 430 431 simple_lock(&ksnew->ks_interlock); 432 ksem_delref(ksnew); 433 return (EEXIST); 434 } 435 goto found_one; 436 } else { 437 /* ksnew already has its initial reference. */ 438 LIST_INSERT_HEAD(&ksem_head, ksnew, ks_entry); 439 simple_unlock(&ksem_slock); 440 441 ksem_add_proc(l->l_proc, ksnew); 442 } 443 return (error); 444 } 445 446 /* We must have a read lock on the ksem_proc list! */ 447 static struct ksem * 448 ksem_lookup_proc(struct ksem_proc *kp, semid_t id) 449 { 450 struct ksem_ref *ksr; 451 452 LIST_FOREACH(ksr, &kp->kp_ksems, ksr_list) { 453 if (id == (semid_t) ksr->ksr_ksem) { 454 simple_lock(&ksr->ksr_ksem->ks_interlock); 455 return (ksr->ksr_ksem); 456 } 457 } 458 459 return (NULL); 460 } 461 462 int 463 sys__ksem_unlink(struct lwp *l, void *v, register_t *retval) 464 { 465 struct sys__ksem_unlink_args /* { 466 const char *name; 467 } */ *uap = v; 468 char name[SEM_MAX_NAMELEN + 1], *cp; 469 size_t done; 470 struct ksem *ks; 471 int error; 472 473 error = copyinstr(SCARG(uap, name), name, sizeof(name), &done); 474 if (error) 475 return error; 476 477 simple_lock(&ksem_slock); 478 ks = ksem_lookup_byname(name); 479 if (ks == NULL) { 480 simple_unlock(&ksem_slock); 481 return (ENOENT); 482 } 483 484 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 485 486 LIST_REMOVE(ks, ks_entry); 487 cp = ks->ks_name; 488 ks->ks_name = NULL; 489 490 simple_unlock(&ksem_slock); 491 492 if (ks->ks_ref == 0) 493 ksem_free(ks); 494 else 495 simple_unlock(&ks->ks_interlock); 496 497 free(cp, M_SEM); 498 499 return (0); 500 } 501 502 int 503 sys__ksem_close(struct lwp *l, void *v, register_t *retval) 504 { 505 struct sys__ksem_close_args /* { 506 semid_t id; 507 } */ *uap = v; 508 struct ksem_proc *kp; 509 struct ksem_ref *ksr; 510 struct ksem *ks; 511 512 if ((kp = l->l_proc->p_ksems) == NULL) 513 return (EINVAL); 514 515 lockmgr(&kp->kp_lock, LK_EXCLUSIVE, NULL); 516 517 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 518 if (ks == NULL) { 519 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 520 return (EINVAL); 521 } 522 523 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 524 if (ks->ks_name == NULL) { 525 simple_unlock(&ks->ks_interlock); 526 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 527 return (EINVAL); 528 } 529 530 ksr = ksem_drop_proc(kp, ks); 531 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 532 free(ksr, M_SEM); 533 534 return (0); 535 } 536 537 int 538 sys__ksem_post(struct lwp *l, void *v, register_t *retval) 539 { 540 struct sys__ksem_post_args /* { 541 semid_t id; 542 } */ *uap = v; 543 struct ksem_proc *kp; 544 struct ksem *ks; 545 int error; 546 547 if ((kp = l->l_proc->p_ksems) == NULL) 548 return (EINVAL); 549 550 lockmgr(&kp->kp_lock, LK_SHARED, NULL); 551 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 552 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 553 if (ks == NULL) 554 return (EINVAL); 555 556 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 557 if (ks->ks_value == SEM_VALUE_MAX) { 558 error = EOVERFLOW; 559 goto out; 560 } 561 ++ks->ks_value; 562 if (ks->ks_waiters) 563 wakeup(ks); 564 error = 0; 565 out: 566 simple_unlock(&ks->ks_interlock); 567 return (error); 568 } 569 570 static int 571 ksem_wait(struct lwp *l, semid_t id, int tryflag) 572 { 573 struct ksem_proc *kp; 574 struct ksem *ks; 575 int error; 576 577 if ((kp = l->l_proc->p_ksems) == NULL) 578 return (EINVAL); 579 580 lockmgr(&kp->kp_lock, LK_SHARED, NULL); 581 ks = ksem_lookup_proc(kp, id); 582 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 583 if (ks == NULL) 584 return (EINVAL); 585 586 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 587 ksem_addref(ks); 588 while (ks->ks_value == 0) { 589 ks->ks_waiters++; 590 error = tryflag ? EAGAIN : ltsleep(ks, PCATCH, "psem", 0, 591 &ks->ks_interlock); 592 ks->ks_waiters--; 593 if (error) 594 goto out; 595 } 596 ks->ks_value--; 597 error = 0; 598 out: 599 ksem_delref(ks); 600 return (error); 601 } 602 603 int 604 sys__ksem_wait(struct lwp *l, void *v, register_t *retval) 605 { 606 struct sys__ksem_wait_args /* { 607 semid_t id; 608 } */ *uap = v; 609 610 return ksem_wait(l, SCARG(uap, id), 0); 611 } 612 613 int 614 sys__ksem_trywait(struct lwp *l, void *v, register_t *retval) 615 { 616 struct sys__ksem_trywait_args /* { 617 semid_t id; 618 } */ *uap = v; 619 620 return ksem_wait(l, SCARG(uap, id), 1); 621 } 622 623 int 624 sys__ksem_getvalue(struct lwp *l, void *v, register_t *retval) 625 { 626 struct sys__ksem_getvalue_args /* { 627 semid_t id; 628 unsigned int *value; 629 } */ *uap = v; 630 struct ksem_proc *kp; 631 struct ksem *ks; 632 unsigned int val; 633 634 if ((kp = l->l_proc->p_ksems) == NULL) 635 return (EINVAL); 636 637 lockmgr(&kp->kp_lock, LK_SHARED, NULL); 638 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 639 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 640 if (ks == NULL) 641 return (EINVAL); 642 643 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 644 val = ks->ks_value; 645 simple_unlock(&ks->ks_interlock); 646 647 return (copyout(&val, SCARG(uap, value), sizeof(val))); 648 } 649 650 int 651 sys__ksem_destroy(struct lwp *l, void *v, register_t *retval) 652 { 653 struct sys__ksem_destroy_args /*{ 654 semid_t id; 655 } */ *uap = v; 656 struct ksem_proc *kp; 657 struct ksem_ref *ksr; 658 struct ksem *ks; 659 660 if ((kp = l->l_proc->p_ksems) == NULL) 661 return (EINVAL); 662 663 lockmgr(&kp->kp_lock, LK_EXCLUSIVE, NULL); 664 665 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 666 if (ks == NULL) { 667 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 668 return (EINVAL); 669 } 670 671 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 672 673 /* 674 * XXX This misses named semaphores which have been unlink'd, 675 * XXX but since behavior of destroying a named semaphore is 676 * XXX undefined, this is technically allowed. 677 */ 678 if (ks->ks_name != NULL) { 679 simple_unlock(&ks->ks_interlock); 680 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 681 return (EINVAL); 682 } 683 684 if (ks->ks_waiters) { 685 simple_unlock(&ks->ks_interlock); 686 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 687 return (EBUSY); 688 } 689 690 ksr = ksem_drop_proc(kp, ks); 691 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 692 free(ksr, M_SEM); 693 694 return (0); 695 } 696 697 static void 698 ksem_forkhook(struct proc *p2, struct proc *p1) 699 { 700 struct ksem_proc *kp1, *kp2; 701 struct ksem_ref *ksr, *ksr1; 702 703 if ((kp1 = p1->p_ksems) == NULL) { 704 p2->p_ksems = NULL; 705 return; 706 } 707 708 p2->p_ksems = kp2 = ksem_proc_alloc(); 709 710 lockmgr(&kp1->kp_lock, LK_SHARED, NULL); 711 712 if (!LIST_EMPTY(&kp1->kp_ksems)) { 713 LIST_FOREACH(ksr, &kp1->kp_ksems, ksr_list) { 714 ksr1 = malloc(sizeof(*ksr), M_SEM, M_WAITOK); 715 ksr1->ksr_ksem = ksr->ksr_ksem; 716 simple_lock(&ksr->ksr_ksem->ks_interlock); 717 ksem_addref(ksr->ksr_ksem); 718 simple_unlock(&ksr->ksr_ksem->ks_interlock); 719 LIST_INSERT_HEAD(&kp2->kp_ksems, ksr1, ksr_list); 720 } 721 } 722 723 lockmgr(&kp1->kp_lock, LK_RELEASE, NULL); 724 } 725 726 static void 727 ksem_exithook(struct lwp *l, void *arg) 728 { 729 struct ksem_proc *kp; 730 struct ksem_ref *ksr; 731 732 if ((kp = l->l_proc->p_ksems) == NULL) 733 return; 734 735 /* Don't bother locking; process is dying. */ 736 737 while ((ksr = LIST_FIRST(&kp->kp_ksems)) != NULL) { 738 LIST_REMOVE(ksr, ksr_list); 739 simple_lock(&ksr->ksr_ksem->ks_interlock); 740 ksem_delref(ksr->ksr_ksem); 741 free(ksr, M_SEM); 742 } 743 } 744 745 void 746 ksem_init(void) 747 { 748 749 simple_lock_init(&ksem_slock); 750 exithook_establish(ksem_exithook, NULL); 751 exechook_establish(ksem_exithook, NULL); 752 forkhook_establish(ksem_forkhook); 753 } 754
Indexes created Sat Oct 11 19:10:01 GMT 2025