uipc_sem.c revision 1.12
1 /* $NetBSD: uipc_sem.c,v 1.12 2005/12/24 19:12:23 perry 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 <sys/cdefs.h> 66 __KERNEL_RCSID(0, "$NetBSD: uipc_sem.c,v 1.12 2005/12/24 19:12:23 perry Exp $"); 67 68 #include "opt_posix.h" 69 70 #include <sys/param.h> 71 #include <sys/systm.h> 72 #include <sys/kernel.h> 73 #include <sys/proc.h> 74 #include <sys/lock.h> 75 #include <sys/ksem.h> 76 #include <sys/sa.h> 77 #include <sys/syscall.h> 78 #include <sys/stat.h> 79 #include <sys/malloc.h> 80 #include <sys/fcntl.h> 81 82 #include <sys/mount.h> 83 84 #include <sys/syscallargs.h> 85 86 #ifndef SEM_MAX 87 #define SEM_MAX 30 88 #endif 89 90 #define SEM_MAX_NAMELEN 14 91 #define SEM_VALUE_MAX (~0U) 92 93 #define SEM_TO_ID(x) ((intptr_t)(x)) 94 95 MALLOC_DEFINE(M_SEM, "p1003_1b_sem", "p1003_1b semaphores"); 96 97 /* 98 * Note: to read the ks_name member, you need either the ks_interlock 99 * or the ksem_slock. To write the ks_name member, you need both. Make 100 * sure the order is ksem_slock -> ks_interlock. 101 */ 102 struct ksem { 103 LIST_ENTRY(ksem) ks_entry; /* global list entry */ 104 struct simplelock ks_interlock; /* lock on this ksem */ 105 char *ks_name; /* if named, this is the name */ 106 unsigned int ks_ref; /* number of references */ 107 mode_t ks_mode; /* protection bits */ 108 uid_t ks_uid; /* creator uid */ 109 gid_t ks_gid; /* creator gid */ 110 unsigned int ks_value; /* current value */ 111 unsigned int ks_waiters; /* number of waiters */ 112 }; 113 114 struct ksem_ref { 115 LIST_ENTRY(ksem_ref) ksr_list; 116 struct ksem *ksr_ksem; 117 }; 118 119 struct ksem_proc { 120 struct lock kp_lock; 121 LIST_HEAD(, ksem_ref) kp_ksems; 122 }; 123 124 /* 125 * ksem_slock protects ksem_head and nsems. Only named semaphores go 126 * onto ksem_head. 127 */ 128 static struct simplelock ksem_slock; 129 static LIST_HEAD(, ksem) ksem_head = LIST_HEAD_INITIALIZER(&ksem_head); 130 static int nsems = 0; 131 132 static void 133 ksem_free(struct ksem *ks) 134 { 135 136 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 137 /* 138 * If the ksem is anonymous (or has been unlinked), then 139 * this is the end if its life. 140 */ 141 if (ks->ks_name == NULL) { 142 simple_unlock(&ks->ks_interlock); 143 free(ks, M_SEM); 144 145 simple_lock(&ksem_slock); 146 nsems--; 147 simple_unlock(&ksem_slock); 148 return; 149 } 150 simple_unlock(&ks->ks_interlock); 151 } 152 153 static inline void 154 ksem_addref(struct ksem *ks) 155 { 156 157 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 158 ks->ks_ref++; 159 KASSERT(ks->ks_ref != 0); /* XXX KDASSERT */ 160 } 161 162 static inline void 163 ksem_delref(struct ksem *ks) 164 { 165 166 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 167 KASSERT(ks->ks_ref != 0); /* XXX KDASSERT */ 168 if (--ks->ks_ref == 0) { 169 ksem_free(ks); 170 return; 171 } 172 simple_unlock(&ks->ks_interlock); 173 } 174 175 static struct ksem_proc * 176 ksem_proc_alloc(void) 177 { 178 struct ksem_proc *kp; 179 180 kp = malloc(sizeof(*kp), M_SEM, M_WAITOK); 181 lockinit(&kp->kp_lock, PWAIT, "ksproc", 0, 0); 182 LIST_INIT(&kp->kp_ksems); 183 184 return (kp); 185 } 186 187 static void 188 ksem_add_proc(struct proc *p, struct ksem *ks) 189 { 190 struct ksem_proc *kp; 191 struct ksem_ref *ksr; 192 193 if (p->p_ksems == NULL) { 194 kp = ksem_proc_alloc(); 195 p->p_ksems = kp; 196 } else 197 kp = p->p_ksems; 198 199 ksr = malloc(sizeof(*ksr), M_SEM, M_WAITOK); 200 ksr->ksr_ksem = ks; 201 202 lockmgr(&kp->kp_lock, LK_EXCLUSIVE, NULL); 203 LIST_INSERT_HEAD(&kp->kp_ksems, ksr, ksr_list); 204 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 205 } 206 207 /* We MUST have a write lock on the ksem_proc list! */ 208 static struct ksem_ref * 209 ksem_drop_proc(struct ksem_proc *kp, struct ksem *ks) 210 { 211 struct ksem_ref *ksr; 212 213 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 214 LIST_FOREACH(ksr, &kp->kp_ksems, ksr_list) { 215 if (ksr->ksr_ksem == ks) { 216 ksem_delref(ks); 217 LIST_REMOVE(ksr, ksr_list); 218 return (ksr); 219 } 220 } 221 #ifdef DIAGNOSTIC 222 panic("ksem_drop_proc: ksem_proc %p ksem %p", kp, ks); 223 #endif 224 return (NULL); 225 } 226 227 static int 228 ksem_perm(struct proc *p, struct ksem *ks) 229 { 230 struct ucred *uc; 231 232 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 233 uc = p->p_ucred; 234 if ((uc->cr_uid == ks->ks_uid && (ks->ks_mode & S_IWUSR) != 0) || 235 (uc->cr_gid == ks->ks_gid && (ks->ks_mode & S_IWGRP) != 0) || 236 (ks->ks_mode & S_IWOTH) != 0 || suser(uc, &p->p_acflag) == 0) 237 return (0); 238 return (EPERM); 239 } 240 241 static struct ksem * 242 ksem_lookup_byname(const char *name) 243 { 244 struct ksem *ks; 245 246 LOCK_ASSERT(simple_lock_held(&ksem_slock)); 247 LIST_FOREACH(ks, &ksem_head, ks_entry) { 248 if (strcmp(ks->ks_name, name) == 0) { 249 simple_lock(&ks->ks_interlock); 250 return (ks); 251 } 252 } 253 return (NULL); 254 } 255 256 static int 257 ksem_create(struct proc *p, const char *name, struct ksem **ksret, 258 mode_t mode, unsigned int value) 259 { 260 struct ksem *ret; 261 struct ucred *uc; 262 size_t len; 263 264 uc = p->p_ucred; 265 if (value > SEM_VALUE_MAX) 266 return (EINVAL); 267 ret = malloc(sizeof(*ret), M_SEM, M_WAITOK | M_ZERO); 268 if (name != NULL) { 269 len = strlen(name); 270 if (len > SEM_MAX_NAMELEN) { 271 free(ret, M_SEM); 272 return (ENAMETOOLONG); 273 } 274 /* name must start with a '/' but not contain one. */ 275 if (*name != '/' || len < 2 || strchr(name + 1, '/') != NULL) { 276 free(ret, M_SEM); 277 return (EINVAL); 278 } 279 ret->ks_name = malloc(len + 1, M_SEM, M_WAITOK); 280 strlcpy(ret->ks_name, name, len + 1); 281 } else 282 ret->ks_name = NULL; 283 ret->ks_mode = mode; 284 ret->ks_value = value; 285 ret->ks_ref = 1; 286 ret->ks_waiters = 0; 287 ret->ks_uid = uc->cr_uid; 288 ret->ks_gid = uc->cr_gid; 289 simple_lock_init(&ret->ks_interlock); 290 291 simple_lock(&ksem_slock); 292 if (nsems >= SEM_MAX) { 293 simple_unlock(&ksem_slock); 294 if (ret->ks_name != NULL) 295 free(ret->ks_name, M_SEM); 296 free(ret, M_SEM); 297 return (ENFILE); 298 } 299 nsems++; 300 simple_unlock(&ksem_slock); 301 302 *ksret = ret; 303 return (0); 304 } 305 306 int 307 sys__ksem_init(struct lwp *l, void *v, register_t *retval) 308 { 309 struct sys__ksem_init_args /* { 310 unsigned int value; 311 semid_t *idp; 312 } */ *uap = v; 313 struct ksem *ks; 314 semid_t id; 315 int error; 316 317 /* Note the mode does not matter for anonymous semaphores. */ 318 error = ksem_create(l->l_proc, NULL, &ks, 0, SCARG(uap, value)); 319 if (error) 320 return (error); 321 id = SEM_TO_ID(ks); 322 error = copyout(&id, SCARG(uap, idp), sizeof(id)); 323 if (error) { 324 simple_lock(&ks->ks_interlock); 325 ksem_delref(ks); 326 return (error); 327 } 328 329 ksem_add_proc(l->l_proc, ks); 330 331 return (0); 332 } 333 334 int 335 sys__ksem_open(struct lwp *l, void *v, register_t *retval) 336 { 337 struct sys__ksem_open_args /* { 338 const char *name; 339 int oflag; 340 mode_t mode; 341 unsigned int value; 342 semid_t *idp; 343 } */ *uap = v; 344 char name[SEM_MAX_NAMELEN + 1]; 345 size_t done; 346 int error; 347 struct ksem *ksnew, *ks; 348 semid_t id; 349 350 error = copyinstr(SCARG(uap, name), name, sizeof(name), &done); 351 if (error) 352 return (error); 353 354 ksnew = NULL; 355 simple_lock(&ksem_slock); 356 ks = ksem_lookup_byname(name); 357 358 /* Found one? */ 359 if (ks != NULL) { 360 /* Check for exclusive create. */ 361 if (SCARG(uap, oflag) & O_EXCL) { 362 simple_unlock(&ks->ks_interlock); 363 simple_unlock(&ksem_slock); 364 return (EEXIST); 365 } 366 found_one: 367 /* 368 * Verify permissions. If we can access it, add 369 * this process's reference. 370 */ 371 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 372 error = ksem_perm(l->l_proc, ks); 373 if (error == 0) 374 ksem_addref(ks); 375 simple_unlock(&ks->ks_interlock); 376 simple_unlock(&ksem_slock); 377 if (error) 378 return (error); 379 380 id = SEM_TO_ID(ks); 381 error = copyout(&id, SCARG(uap, idp), sizeof(id)); 382 if (error) { 383 simple_lock(&ks->ks_interlock); 384 ksem_delref(ks); 385 return (error); 386 } 387 388 ksem_add_proc(l->l_proc, ks); 389 390 return (0); 391 } 392 393 /* 394 * didn't ask for creation? error. 395 */ 396 if ((SCARG(uap, oflag) & O_CREAT) == 0) { 397 simple_unlock(&ksem_slock); 398 return (ENOENT); 399 } 400 401 /* 402 * We may block during creation, so drop the lock. 403 */ 404 simple_unlock(&ksem_slock); 405 error = ksem_create(l->l_proc, name, &ksnew, SCARG(uap, mode), 406 SCARG(uap, value)); 407 if (error != 0) 408 return (error); 409 410 id = SEM_TO_ID(ksnew); 411 error = copyout(&id, SCARG(uap, idp), sizeof(id)); 412 if (error) { 413 free(ksnew->ks_name, M_SEM); 414 ksnew->ks_name = NULL; 415 416 simple_lock(&ksnew->ks_interlock); 417 ksem_delref(ksnew); 418 return (error); 419 } 420 421 /* 422 * We need to make sure we haven't lost a race while 423 * allocating during creation. 424 */ 425 simple_lock(&ksem_slock); 426 if ((ks = ksem_lookup_byname(name)) != NULL) { 427 if (SCARG(uap, oflag) & O_EXCL) { 428 simple_unlock(&ks->ks_interlock); 429 simple_unlock(&ksem_slock); 430 431 free(ksnew->ks_name, M_SEM); 432 ksnew->ks_name = NULL; 433 434 simple_lock(&ksnew->ks_interlock); 435 ksem_delref(ksnew); 436 return (EEXIST); 437 } 438 goto found_one; 439 } else { 440 /* ksnew already has its initial reference. */ 441 LIST_INSERT_HEAD(&ksem_head, ksnew, ks_entry); 442 simple_unlock(&ksem_slock); 443 444 ksem_add_proc(l->l_proc, ksnew); 445 } 446 return (error); 447 } 448 449 /* We must have a read lock on the ksem_proc list! */ 450 static struct ksem * 451 ksem_lookup_proc(struct ksem_proc *kp, semid_t id) 452 { 453 struct ksem_ref *ksr; 454 455 LIST_FOREACH(ksr, &kp->kp_ksems, ksr_list) { 456 if (id == (semid_t) ksr->ksr_ksem) { 457 simple_lock(&ksr->ksr_ksem->ks_interlock); 458 return (ksr->ksr_ksem); 459 } 460 } 461 462 return (NULL); 463 } 464 465 int 466 sys__ksem_unlink(struct lwp *l, void *v, register_t *retval) 467 { 468 struct sys__ksem_unlink_args /* { 469 const char *name; 470 } */ *uap = v; 471 char name[SEM_MAX_NAMELEN + 1], *cp; 472 size_t done; 473 struct ksem *ks; 474 int error; 475 476 error = copyinstr(SCARG(uap, name), name, sizeof(name), &done); 477 if (error) 478 return error; 479 480 simple_lock(&ksem_slock); 481 ks = ksem_lookup_byname(name); 482 if (ks == NULL) { 483 simple_unlock(&ksem_slock); 484 return (ENOENT); 485 } 486 487 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 488 489 LIST_REMOVE(ks, ks_entry); 490 cp = ks->ks_name; 491 ks->ks_name = NULL; 492 493 simple_unlock(&ksem_slock); 494 495 if (ks->ks_ref == 0) 496 ksem_free(ks); 497 else 498 simple_unlock(&ks->ks_interlock); 499 500 free(cp, M_SEM); 501 502 return (0); 503 } 504 505 int 506 sys__ksem_close(struct lwp *l, void *v, register_t *retval) 507 { 508 struct sys__ksem_close_args /* { 509 semid_t id; 510 } */ *uap = v; 511 struct ksem_proc *kp; 512 struct ksem_ref *ksr; 513 struct ksem *ks; 514 515 if ((kp = l->l_proc->p_ksems) == NULL) 516 return (EINVAL); 517 518 lockmgr(&kp->kp_lock, LK_EXCLUSIVE, NULL); 519 520 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 521 if (ks == NULL) { 522 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 523 return (EINVAL); 524 } 525 526 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 527 if (ks->ks_name == NULL) { 528 simple_unlock(&ks->ks_interlock); 529 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 530 return (EINVAL); 531 } 532 533 ksr = ksem_drop_proc(kp, ks); 534 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 535 free(ksr, M_SEM); 536 537 return (0); 538 } 539 540 int 541 sys__ksem_post(struct lwp *l, void *v, register_t *retval) 542 { 543 struct sys__ksem_post_args /* { 544 semid_t id; 545 } */ *uap = v; 546 struct ksem_proc *kp; 547 struct ksem *ks; 548 int error; 549 550 if ((kp = l->l_proc->p_ksems) == NULL) 551 return (EINVAL); 552 553 lockmgr(&kp->kp_lock, LK_SHARED, NULL); 554 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 555 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 556 if (ks == NULL) 557 return (EINVAL); 558 559 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 560 if (ks->ks_value == SEM_VALUE_MAX) { 561 error = EOVERFLOW; 562 goto out; 563 } 564 ++ks->ks_value; 565 if (ks->ks_waiters) 566 wakeup(ks); 567 error = 0; 568 out: 569 simple_unlock(&ks->ks_interlock); 570 return (error); 571 } 572 573 static int 574 ksem_wait(struct lwp *l, semid_t id, int tryflag) 575 { 576 struct ksem_proc *kp; 577 struct ksem *ks; 578 int error; 579 580 if ((kp = l->l_proc->p_ksems) == NULL) 581 return (EINVAL); 582 583 lockmgr(&kp->kp_lock, LK_SHARED, NULL); 584 ks = ksem_lookup_proc(kp, id); 585 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 586 if (ks == NULL) 587 return (EINVAL); 588 589 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 590 ksem_addref(ks); 591 while (ks->ks_value == 0) { 592 ks->ks_waiters++; 593 error = tryflag ? EAGAIN : ltsleep(ks, PCATCH, "psem", 0, 594 &ks->ks_interlock); 595 ks->ks_waiters--; 596 if (error) 597 goto out; 598 } 599 ks->ks_value--; 600 error = 0; 601 out: 602 ksem_delref(ks); 603 return (error); 604 } 605 606 int 607 sys__ksem_wait(struct lwp *l, void *v, register_t *retval) 608 { 609 struct sys__ksem_wait_args /* { 610 semid_t id; 611 } */ *uap = v; 612 613 return ksem_wait(l, SCARG(uap, id), 0); 614 } 615 616 int 617 sys__ksem_trywait(struct lwp *l, void *v, register_t *retval) 618 { 619 struct sys__ksem_trywait_args /* { 620 semid_t id; 621 } */ *uap = v; 622 623 return ksem_wait(l, SCARG(uap, id), 1); 624 } 625 626 int 627 sys__ksem_getvalue(struct lwp *l, void *v, register_t *retval) 628 { 629 struct sys__ksem_getvalue_args /* { 630 semid_t id; 631 unsigned int *value; 632 } */ *uap = v; 633 struct ksem_proc *kp; 634 struct ksem *ks; 635 unsigned int val; 636 637 if ((kp = l->l_proc->p_ksems) == NULL) 638 return (EINVAL); 639 640 lockmgr(&kp->kp_lock, LK_SHARED, NULL); 641 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 642 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 643 if (ks == NULL) 644 return (EINVAL); 645 646 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 647 val = ks->ks_value; 648 simple_unlock(&ks->ks_interlock); 649 650 return (copyout(&val, SCARG(uap, value), sizeof(val))); 651 } 652 653 int 654 sys__ksem_destroy(struct lwp *l, void *v, register_t *retval) 655 { 656 struct sys__ksem_destroy_args /*{ 657 semid_t id; 658 } */ *uap = v; 659 struct ksem_proc *kp; 660 struct ksem_ref *ksr; 661 struct ksem *ks; 662 663 if ((kp = l->l_proc->p_ksems) == NULL) 664 return (EINVAL); 665 666 lockmgr(&kp->kp_lock, LK_EXCLUSIVE, NULL); 667 668 ks = ksem_lookup_proc(kp, SCARG(uap, id)); 669 if (ks == NULL) { 670 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 671 return (EINVAL); 672 } 673 674 LOCK_ASSERT(simple_lock_held(&ks->ks_interlock)); 675 676 /* 677 * XXX This misses named semaphores which have been unlink'd, 678 * XXX but since behavior of destroying a named semaphore is 679 * XXX undefined, this is technically allowed. 680 */ 681 if (ks->ks_name != NULL) { 682 simple_unlock(&ks->ks_interlock); 683 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 684 return (EINVAL); 685 } 686 687 if (ks->ks_waiters) { 688 simple_unlock(&ks->ks_interlock); 689 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 690 return (EBUSY); 691 } 692 693 ksr = ksem_drop_proc(kp, ks); 694 lockmgr(&kp->kp_lock, LK_RELEASE, NULL); 695 free(ksr, M_SEM); 696 697 return (0); 698 } 699 700 static void 701 ksem_forkhook(struct proc *p2, struct proc *p1) 702 { 703 struct ksem_proc *kp1, *kp2; 704 struct ksem_ref *ksr, *ksr1; 705 706 if ((kp1 = p1->p_ksems) == NULL) { 707 p2->p_ksems = NULL; 708 return; 709 } 710 711 p2->p_ksems = kp2 = ksem_proc_alloc(); 712 713 lockmgr(&kp1->kp_lock, LK_SHARED, NULL); 714 715 if (!LIST_EMPTY(&kp1->kp_ksems)) { 716 LIST_FOREACH(ksr, &kp1->kp_ksems, ksr_list) { 717 ksr1 = malloc(sizeof(*ksr), M_SEM, M_WAITOK); 718 ksr1->ksr_ksem = ksr->ksr_ksem; 719 simple_lock(&ksr->ksr_ksem->ks_interlock); 720 ksem_addref(ksr->ksr_ksem); 721 simple_unlock(&ksr->ksr_ksem->ks_interlock); 722 LIST_INSERT_HEAD(&kp2->kp_ksems, ksr1, ksr_list); 723 } 724 } 725 726 lockmgr(&kp1->kp_lock, LK_RELEASE, NULL); 727 } 728 729 static void 730 ksem_exithook(struct proc *p, void *arg) 731 { 732 struct ksem_proc *kp; 733 struct ksem_ref *ksr; 734 735 if ((kp = p->p_ksems) == NULL) 736 return; 737 738 /* Don't bother locking; process is dying. */ 739 740 while ((ksr = LIST_FIRST(&kp->kp_ksems)) != NULL) { 741 LIST_REMOVE(ksr, ksr_list); 742 simple_lock(&ksr->ksr_ksem->ks_interlock); 743 ksem_delref(ksr->ksr_ksem); 744 free(ksr, M_SEM); 745 } 746 } 747 748 void 749 ksem_init(void) 750 { 751 752 simple_lock_init(&ksem_slock); 753 exithook_establish(ksem_exithook, NULL); 754 exechook_establish(ksem_exithook, NULL); 755 forkhook_establish(ksem_forkhook); 756 } 757
Indexes created Tue Sep 23 07:09:52 GMT 2025