uipc_sem.c revision 1.3
1 /* $NetBSD: uipc_sem.c,v 1.3 2003/01/24 01:46:27 thorpej 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/syscall.h> 74 #include <sys/stat.h> 75 #include <sys/malloc.h> 76 #include <sys/fcntl.h> 77 78 #include <sys/mount.h> 79 80 #include <sys/syscallargs.h> 81 82 #ifndef SEM_MAX 83 #define SEM_MAX 30 84 #endif 85 86 #define SEM_MAX_NAMELEN 14 87 #define SEM_VALUE_MAX (~0U) 88 89 #define SEM_TO_ID(x) ((intptr_t)(x)) 90 91 /* 92 * Note: to read the ks_name member, you need either the ks_interlock 93 * or the ksem_slock. To write the ks_name member, you need both. Make 94 * sure the order is ksem_slock -> ks_interlock. 95 */ 96 struct ksem { 97 LIST_ENTRY(ksem) ks_entry; /* global list entry */ 98 struct simplelock ks_interlock; /* lock on this ksem */ 99 char *ks_name; /* if named, this is the name */ 100 unsigned int ks_ref; /* number of references */ 101 mode_t ks_mode; /* protection bits */ 102 uid_t ks_uid; /* creator uid */ 103 gid_t ks_gid; /* creator gid */ 104 unsigned int ks_value; /* current value */ 105 unsigned int ks_waiters; /* number of waiters */ 106 }; 107 108 struct ksem_ref { 109 LIST_ENTRY(ksem_ref) ksr_list; 110 struct ksem *ksr_ksem; 111 }; 112 113 struct ksem_proc { 114 struct lock kp_lock; 115 LIST_HEAD(, ksem_ref) kp_ksems; 116 }; 117 118 /* 119 * ksem_slock protects ksem_head and nsems. Only named semaphores go 120 * onto ksem_head. 121 */ 122 static struct simplelock ksem_slock; 123 static LIST_HEAD(, ksem) ksem_head = LIST_HEAD_INITIALIZER(&ksem_head); 124 static int nsems = 0; 125 126 static void 127 ksem_free(struct ksem *ks) 128 { 129 130 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 131 /* 132 * If the ksem is anonymous (or has been unlinked), then 133 * this is the end if its life. 134 */ 135 if (ks->ks_name == NULL) { 136 simple_unlock(&ks->ks_interlock); 137 free(ks, M_SEM); 138 139 simple_lock(&ksem_slock); 140 nsems--; 141 simple_unlock(&ksem_slock); 142 return; 143 } 144 simple_unlock(&ks->ks_interlock); 145 } 146 147 static __inline void 148 ksem_addref(struct ksem *ks) 149 { 150 151 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 152 ks->ks_ref++; 153 KASSERT(ks->ks_ref != 0); /* XXX KDASSERT */ 154 } 155 156 static __inline void 157 ksem_delref(struct ksem *ks) 158 { 159 160 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 161 KASSERT(ks->ks_ref != 0); /* XXX KDASSERT */ 162 if (--ks->ks_ref == 0) { 163 ksem_free(ks); 164 return; 165 } 166 simple_unlock(&ks->ks_interlock); 167 } 168 169 static struct ksem_proc * 170 ksem_proc_alloc(void) 171 { 172 struct ksem_proc *kp; 173 174 kp = malloc(sizeof(*kp), M_SEM, M_WAITOK); 175 lockinit(&kp->kp_lock, PWAIT, "ksproc", 0, 0); 176 LIST_INIT(&kp->kp_ksems); 177 178 return (kp); 179 } 180 181 static void 182 ksem_add_proc(struct proc *p, struct ksem *ks) 183 { 184 struct ksem_proc *kp; 185 struct ksem_ref *ksr; 186 187 if (p->p_ksems == NULL) { 188 kp = ksem_proc_alloc(); 189 p->p_ksems = kp; 190 } else 191 kp = p->p_ksems; 192 193 ksr = malloc(sizeof(*ksr), M_SEM, M_WAITOK); 194 ksr->ksr_ksem = ks; 195 196 lockmgr(&kp->kp_lock, LK_EXCLUSIVE, NULL); 197 LIST_INSERT_HEAD(&kp->kp_ksems, ksr, ksr_list); 198 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 199 } 200 201 /* We MUST have a write lock on the ksem_proc list! */ 202 static struct ksem_ref * 203 ksem_drop_proc(struct ksem_proc *kp, struct ksem *ks) 204 { 205 struct ksem_ref *ksr; 206 207 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 208 LIST_FOREACH(ksr, &kp->kp_ksems, ksr_list) { 209 if (ksr->ksr_ksem == ks) { 210 ksem_delref(ks); 211 LIST_REMOVE(ksr, ksr_list); 212 return (ksr); 213 } 214 } 215 #ifdef DIAGNOSTIC 216 panic("ksem_drop_proc: ksem_proc %p ksem %p", kp, ks); 217 #endif 218 return (NULL); 219 } 220 221 static int 222 ksem_perm(struct proc *p, struct ksem *ks) 223 { 224 struct ucred *uc; 225 226 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 227 uc = p->p_ucred; 228 if ((uc->cr_uid == ks->ks_uid && (ks->ks_mode & S_IWUSR) != 0) || 229 (uc->cr_gid == ks->ks_gid && (ks->ks_mode & S_IWGRP) != 0) || 230 (ks->ks_mode & S_IWOTH) != 0 || suser(uc, &p->p_acflag) == 0) 231 return (0); 232 return (EPERM); 233 } 234 235 static struct ksem * 236 ksem_lookup_byname(const char *name) 237 { 238 struct ksem *ks; 239 240 LOCK_ASSERT(simple_lock_held(&ksem_slock)); 241 LIST_FOREACH(ks, &ksem_head, ks_entry) { 242 if (strcmp(ks->ks_name, name) == 0) { 243 simple_lock(&ks->ks_interlock); 244 return (ks); 245 } 246 } 247 return (NULL); 248 } 249 250 static int 251 ksem_create(struct proc *p, const char *name, struct ksem **ksret, 252 mode_t mode, unsigned int value) 253 { 254 struct ksem *ret; 255 struct ucred *uc; 256 size_t len; 257 258 uc = p->p_ucred; 259 if (value > SEM_VALUE_MAX) 260 return (EINVAL); 261 ret = malloc(sizeof(*ret), M_SEM, M_WAITOK | M_ZERO); 262 if (name != NULL) { 263 len = strlen(name); 264 if (len > SEM_MAX_NAMELEN) { 265 free(ret, M_SEM); 266 return (ENAMETOOLONG); 267 } 268 /* name must start with a '/' but not contain one. */ 269 if (*name != '/' || len < 2 || strchr(name + 1, '/') != NULL) { 270 free(ret, M_SEM); 271 return (EINVAL); 272 } 273 ret->ks_name = malloc(len + 1, M_SEM, M_WAITOK); 274 strcpy(ret->ks_name, name); 275 } else 276 ret->ks_name = NULL; 277 ret->ks_mode = mode; 278 ret->ks_value = value; 279 ret->ks_ref = 1; 280 ret->ks_waiters = 0; 281 ret->ks_uid = uc->cr_uid; 282 ret->ks_gid = uc->cr_gid; 283 simple_lock_init(&ret->ks_interlock); 284 285 simple_lock(&ksem_slock); 286 if (nsems >= SEM_MAX) { 287 simple_unlock(&ksem_slock); 288 if (ret->ks_name != NULL) 289 free(ret->ks_name, M_SEM); 290 free(ret, M_SEM); 291 return (ENFILE); 292 } 293 nsems++; 294 simple_unlock(&ksem_slock); 295 296 *ksret = ret; 297 return (0); 298 } 299 300 int 301 sys__ksem_init(struct lwp *l, void *v, register_t *retval) 302 { 303 struct sys__ksem_init_args /* { 304 unsigned int value; 305 semid_t *idp; 306 } */ *uap = v; 307 struct ksem *ks; 308 semid_t id; 309 int error; 310 311 /* Note the mode does not matter for anonymous semaphores. */ 312 error = ksem_create(l->l_proc, NULL, &ks, 0, SCARG(uap, value)); 313 if (error) 314 return (error); 315 id = SEM_TO_ID(ks); 316 error = copyout(&id, SCARG(uap, idp), sizeof(id)); 317 if (error) { 318 simple_lock(&ks->ks_interlock); 319 ksem_delref(ks); 320 return (error); 321 } 322 323 ksem_add_proc(l->l_proc, ks); 324 325 return (0); 326 } 327 328 int 329 sys__ksem_open(struct lwp *l, void *v, register_t *retval) 330 { 331 struct sys__ksem_open_args /* { 332 const char *name; 333 int oflag; 334 mode_t mode; 335 unsigned int value; 336 semid_t *idp; 337 } */ *uap = v; 338 char name[SEM_MAX_NAMELEN + 1]; 339 size_t done; 340 int error; 341 struct ksem *ksnew, *ks; 342 semid_t id; 343 344 error = copyinstr(SCARG(uap, name), name, sizeof(name), &done); 345 if (error) 346 return (error); 347 348 ksnew = NULL; 349 simple_lock(&ksem_slock); 350 ks = ksem_lookup_byname(name); 351 352 /* Found one? */ 353 if (ks != NULL) { 354 /* Check for exclusive create. */ 355 if (SCARG(uap, oflag) & O_EXCL) { 356 simple_unlock(&ks->ks_interlock); 357 simple_unlock(&ksem_slock); 358 return (EEXIST); 359 } 360 found_one: 361 /* 362 * Verify permissions. If we can access it, add 363 * this process's reference. 364 */ 365 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 366 error = ksem_perm(l->l_proc, ks); 367 if (error == 0) 368 ksem_addref(ks); 369 simple_unlock(&ks->ks_interlock); 370 simple_unlock(&ksem_slock); 371 if (error) 372 return (error); 373 374 id = SEM_TO_ID(ks); 375 error = copyout(&id, SCARG(uap, idp), sizeof(id)); 376 if (error) { 377 simple_lock(&ks->ks_interlock); 378 ksem_delref(ks); 379 return (error); 380 } 381 382 ksem_add_proc(l->l_proc, ks); 383 384 return (0); 385 } 386 387 /* 388 * didn't ask for creation? error. 389 */ 390 if ((SCARG(uap, oflag) & O_CREAT) == 0) { 391 simple_unlock(&ksem_slock); 392 return (ENOENT); 393 } 394 395 /* 396 * We may block during creation, so drop the lock. 397 */ 398 simple_unlock(&ksem_slock); 399 error = ksem_create(l->l_proc, name, &ksnew, SCARG(uap, mode), 400 SCARG(uap, value)); 401 if (error != 0) 402 return (error); 403 404 id = SEM_TO_ID(ksnew); 405 error = copyout(&id, SCARG(uap, idp), sizeof(id)); 406 if (error) { 407 free(ksnew->ks_name, M_SEM); 408 ksnew->ks_name = NULL; 409 410 simple_lock(&ksnew->ks_interlock); 411 ksem_delref(ksnew); 412 return (error); 413 } 414 415 /* 416 * We need to make sure we haven't lost a race while 417 * allocating during creation. 418 */ 419 simple_lock(&ksem_slock); 420 if ((ks = ksem_lookup_byname(name)) != NULL) { 421 if (SCARG(uap, oflag) & O_EXCL) { 422 simple_unlock(&ks->ks_interlock); 423 simple_unlock(&ksem_slock); 424 425 free(ksnew->ks_name, M_SEM); 426 ksnew->ks_name = NULL; 427 428 simple_lock(&ksnew->ks_interlock); 429 ksem_delref(ksnew); 430 return (EEXIST); 431 } 432 goto found_one; 433 } else { 434 /* ksnew already has its initial reference. */ 435 LIST_INSERT_HEAD(&ksem_head, ksnew, ks_entry); 436 simple_unlock(&ksem_slock); 437 438 ksem_add_proc(l->l_proc, ksnew); 439 } 440 return (error); 441 } 442 443 /* We must have a read lock on the ksem_proc list! */ 444 static struct ksem * 445 ksem_lookup_proc(struct ksem_proc *kp, semid_t id) 446 { 447 struct ksem_ref *ksr; 448 449 LIST_FOREACH(ksr, &kp->kp_ksems, ksr_list) { 450 if (id == (semid_t) ksr->ksr_ksem) { 451 simple_lock(&ksr->ksr_ksem->ks_interlock); 452 return (ksr->ksr_ksem); 453 } 454 } 455 456 return (NULL); 457 } 458 459 int 460 sys__ksem_unlink(struct lwp *l, void *v, register_t *retval) 461 { 462 struct sys__ksem_unlink_args /* { 463 const char *name; 464 } */ *uap = v; 465 char name[SEM_MAX_NAMELEN + 1], *cp; 466 size_t done; 467 struct ksem *ks; 468 int error; 469 470 error = copyinstr(SCARG(uap, name), name, sizeof(name), &done); 471 if (error) 472 return error; 473 474 simple_lock(&ksem_slock); 475 ks = ksem_lookup_byname(name); 476 if (ks == NULL) { 477 simple_unlock(&ksem_slock); 478 return (ENOENT); 479 } 480 481 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 482 483 LIST_REMOVE(ks, ks_entry); 484 cp = ks->ks_name; 485 ks->ks_name = NULL; 486 487 simple_unlock(&ksem_slock); 488 489 if (ks->ks_ref == 0) 490 ksem_free(ks); 491 else 492 simple_unlock(&ks->ks_interlock); 493 494 free(cp, M_SEM); 495 496 return (0); 497 } 498 499 int 500 sys__ksem_close(struct lwp *l, void *v, register_t *retval) 501 { 502 struct sys__ksem_close_args /* { 503 semid_t id; 504 } */ *uap = v; 505 struct ksem_proc *kp; 506 struct ksem_ref *ksr; 507 struct ksem *ks; 508 509 if ((kp = l->l_proc->p_ksems) == NULL) 510 return (EINVAL); 511 512 lockmgr(&kp->kp_lock, LK_EXCLUSIVE, NULL); 513 514 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 515 if (ks == NULL) { 516 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 517 return (EINVAL); 518 } 519 520 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 521 if (ks->ks_name == NULL) { 522 simple_unlock(&ks->ks_interlock); 523 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 524 return (EINVAL); 525 } 526 527 ksr = ksem_drop_proc(kp, ks); 528 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 529 free(ksr, M_SEM); 530 531 return (0); 532 } 533 534 int 535 sys__ksem_post(struct lwp *l, void *v, register_t *retval) 536 { 537 struct sys__ksem_post_args /* { 538 semid_t id; 539 } */ *uap = v; 540 struct ksem_proc *kp; 541 struct ksem *ks; 542 int error; 543 544 if ((kp = l->l_proc->p_ksems) == NULL) 545 return (EINVAL); 546 547 lockmgr(&kp->kp_lock, LK_SHARED, NULL); 548 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 549 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 550 if (ks == NULL) 551 return (EINVAL); 552 553 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 554 if (ks->ks_value == SEM_VALUE_MAX) { 555 error = EOVERFLOW; 556 goto out; 557 } 558 ++ks->ks_value; 559 if (ks->ks_waiters) 560 wakeup(ks); 561 error = 0; 562 out: 563 simple_unlock(&ks->ks_interlock); 564 return (error); 565 } 566 567 static int 568 ksem_wait(struct lwp *l, semid_t id, int tryflag) 569 { 570 struct ksem_proc *kp; 571 struct ksem *ks; 572 int error; 573 574 if ((kp = l->l_proc->p_ksems) == NULL) 575 return (EINVAL); 576 577 lockmgr(&kp->kp_lock, LK_SHARED, NULL); 578 ks = ksem_lookup_proc(kp, id); 579 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 580 if (ks == NULL) 581 return (EINVAL); 582 583 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 584 ksem_addref(ks); 585 while (ks->ks_value == 0) { 586 ks->ks_waiters++; 587 error = tryflag ? EAGAIN : ltsleep(ks, PCATCH, "psem", 0, 588 &ks->ks_interlock); 589 ks->ks_waiters--; 590 if (error) 591 goto out; 592 } 593 ks->ks_value--; 594 error = 0; 595 out: 596 ksem_delref(ks); 597 return (error); 598 } 599 600 int 601 sys__ksem_wait(struct lwp *l, void *v, register_t *retval) 602 { 603 struct sys__ksem_wait_args /* { 604 semid_t id; 605 } */ *uap = v; 606 607 return ksem_wait(l, SCARG(uap, id), 0); 608 } 609 610 int 611 sys__ksem_trywait(struct lwp *l, void *v, register_t *retval) 612 { 613 struct sys__ksem_trywait_args /* { 614 semid_t id; 615 } */ *uap = v; 616 617 return ksem_wait(l, SCARG(uap, id), 1); 618 } 619 620 int 621 sys__ksem_getvalue(struct lwp *l, void *v, register_t *retval) 622 { 623 struct sys__ksem_getvalue_args /* { 624 semid_t id; 625 unsigned int *value; 626 } */ *uap = v; 627 struct ksem_proc *kp; 628 struct ksem *ks; 629 unsigned int val; 630 631 if ((kp = l->l_proc->p_ksems) == NULL) 632 return (EINVAL); 633 634 lockmgr(&kp->kp_lock, LK_SHARED, NULL); 635 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 636 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 637 if (ks == NULL) 638 return (EINVAL); 639 640 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 641 val = ks->ks_value; 642 simple_unlock(&ks->ks_interlock); 643 644 return (copyout(&val, SCARG(uap, value), sizeof(val))); 645 } 646 647 int 648 sys__ksem_destroy(struct lwp *l, void *v, register_t *retval) 649 { 650 struct sys__ksem_destroy_args /*{ 651 semid_t id; 652 } */ *uap = v; 653 struct ksem_proc *kp; 654 struct ksem_ref *ksr; 655 struct ksem *ks; 656 657 if ((kp = l->l_proc->p_ksems) == NULL) 658 return (EINVAL); 659 660 lockmgr(&kp->kp_lock, LK_EXCLUSIVE, NULL); 661 662 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 663 if (ks == NULL) { 664 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 665 return (EINVAL); 666 } 667 668 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 669 670 /* 671 * XXX This misses named semaphores which have been unlink'd, 672 * XXX but since behavior of destroying a named semaphore is 673 * XXX undefined, this is technically allowed. 674 */ 675 if (ks->ks_name != NULL) { 676 simple_unlock(&ks->ks_interlock); 677 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 678 return (EINVAL); 679 } 680 681 if (ks->ks_waiters) { 682 simple_unlock(&ks->ks_interlock); 683 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 684 return (EBUSY); 685 } 686 687 ksr = ksem_drop_proc(kp, ks); 688 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 689 free(ksr, M_SEM); 690 691 return (0); 692 } 693 694 static void 695 ksem_forkhook(struct proc *p2, struct proc *p1) 696 { 697 struct ksem_proc *kp1, *kp2; 698 struct ksem_ref *ksr, *ksr1; 699 700 if ((kp1 = p1->p_ksems) == NULL) { 701 p2->p_ksems = NULL; 702 return; 703 } 704 705 p2->p_ksems = kp2 = ksem_proc_alloc(); 706 707 lockmgr(&kp1->kp_lock, LK_SHARED, NULL); 708 709 if (!LIST_EMPTY(&kp1->kp_ksems)) { 710 LIST_FOREACH(ksr, &kp1->kp_ksems, ksr_list) { 711 ksr1 = malloc(sizeof(*ksr), M_SEM, M_WAITOK); 712 ksr1->ksr_ksem = ksr->ksr_ksem; 713 simple_lock(&ksr->ksr_ksem->ks_interlock); 714 ksem_addref(ksr->ksr_ksem); 715 simple_unlock(&ksr->ksr_ksem->ks_interlock); 716 LIST_INSERT_HEAD(&kp2->kp_ksems, ksr1, ksr_list); 717 } 718 } 719 720 lockmgr(&kp1->kp_lock, LK_RELEASE, NULL); 721 } 722 723 static void 724 ksem_exithook(struct proc *p, void *arg) 725 { 726 struct ksem_proc *kp; 727 struct ksem_ref *ksr; 728 729 if ((kp = p->p_ksems) == NULL) 730 return; 731 732 /* Don't bother locking; process is dying. */ 733 734 while ((ksr = LIST_FIRST(&kp->kp_ksems)) != NULL) { 735 LIST_REMOVE(ksr, ksr_list); 736 simple_lock(&ksr->ksr_ksem->ks_interlock); 737 ksem_delref(ksr->ksr_ksem); 738 free(ksr, M_SEM); 739 } 740 } 741 742 void 743 ksem_init(void) 744 { 745 746 simple_lock_init(&ksem_slock); 747 exithook_establish(ksem_exithook, NULL); 748 exechook_establish(ksem_exithook, NULL); 749 forkhook_establish(ksem_forkhook); 750 } 751
Indexes created Thu Sep 25 16:09:42 GMT 2025