Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]
FreeBSD/Linux Kernel Cross Reference
sys/kern/sysv_sem.c
Version:
- FREEBSD - FREEBSD-13-STABLE - FREEBSD-13-0 - FREEBSD-12-STABLE - FREEBSD-12-0 - FREEBSD-11-STABLE - FREEBSD-11-0 - FREEBSD-10-STABLE - FREEBSD-10-0 - FREEBSD-9-STABLE - FREEBSD-9-0 - FREEBSD-8-STABLE - FREEBSD-8-0 - FREEBSD-7-STABLE - FREEBSD-7-0 - FREEBSD-6-STABLE - FREEBSD-6-0 - FREEBSD-5-STABLE - FREEBSD-5-0 - FREEBSD-4-STABLE - FREEBSD-3-STABLE - FREEBSD22 - l41 - OPENBSD - linux-2.6 - MK84 - PLAN9 - xnu-8792
SearchContext: - none - 3 - 10
SearchContext: - none - 3 - 10
1 /* $NetBSD: sysv_sem.c,v 1.84 2008/09/19 11:21:33 rmind Exp $ */ 2 3 /*- 4 * Copyright (c) 1999, 2007 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 the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center, and by Andrew Doran. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 * Implementation of SVID semaphores 35 * 36 * Author: Daniel Boulet 37 * 38 * This software is provided ``AS IS'' without any warranties of any kind. 39 */ 40 41 #include <sys/cdefs.h> 42 __KERNEL_RCSID(0, "$NetBSD: sysv_sem.c,v 1.84 2008/09/19 11:21:33 rmind Exp $"); 43 44 #define SYSVSEM 45 46 #include <sys/param.h> 47 #include <sys/kernel.h> 48 #include <sys/sem.h> 49 #include <sys/sysctl.h> 50 #include <sys/kmem.h> 51 #include <sys/mount.h> /* XXX for <sys/syscallargs.h> */ 52 #include <sys/syscallargs.h> 53 #include <sys/kauth.h> 54 55 /* 56 * Memory areas: 57 * 1st: Pool of semaphore identifiers 58 * 2nd: Semaphores 59 * 3rd: Conditional variables 60 * 4th: Undo structures 61 */ 62 struct semid_ds *sema; 63 static struct __sem *sem; 64 static kcondvar_t *semcv; 65 static int *semu; 66 67 static kmutex_t semlock; 68 static struct sem_undo *semu_list; /* list of active undo structures */ 69 static u_int semtot = 0; /* total number of semaphores */ 70 71 static u_int sem_waiters = 0; /* total number of semop waiters */ 72 static bool sem_realloc_state; 73 static kcondvar_t sem_realloc_cv; 74 75 /* Macro to find a particular sem_undo vector */ 76 #define SEMU(s, ix) ((struct sem_undo *)(((long)s) + ix * seminfo.semusz)) 77 78 #ifdef SEM_DEBUG 79 #define SEM_PRINTF(a) printf a 80 #else 81 #define SEM_PRINTF(a) 82 #endif 83 84 struct sem_undo *semu_alloc(struct proc *); 85 int semundo_adjust(struct proc *, struct sem_undo **, int, int, int); 86 void semundo_clear(int, int); 87 88 void 89 seminit(void) 90 { 91 int i, sz; 92 vaddr_t v; 93 94 mutex_init(&semlock, MUTEX_DEFAULT, IPL_NONE); 95 cv_init(&sem_realloc_cv, "semrealc"); 96 sem_realloc_state = false; 97 98 /* Allocate the wired memory for our structures */ 99 sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) + 100 ALIGN(seminfo.semmns * sizeof(struct __sem)) + 101 ALIGN(seminfo.semmni * sizeof(kcondvar_t)) + 102 ALIGN(seminfo.semmnu * seminfo.semusz); 103 v = uvm_km_alloc(kernel_map, round_page(sz), 0, 104 UVM_KMF_WIRED|UVM_KMF_ZERO); 105 if (v == 0) 106 panic("sysv_sem: cannot allocate memory"); 107 sema = (void *)v; 108 sem = (void *)((uintptr_t)sema + 109 ALIGN(seminfo.semmni * sizeof(struct semid_ds))); 110 semcv = (void *)((uintptr_t)sem + 111 ALIGN(seminfo.semmns * sizeof(struct __sem))); 112 semu = (void *)((uintptr_t)semcv + 113 ALIGN(seminfo.semmni * sizeof(kcondvar_t))); 114 115 for (i = 0; i < seminfo.semmni; i++) { 116 sema[i]._sem_base = 0; 117 sema[i].sem_perm.mode = 0; 118 cv_init(&semcv[i], "semwait"); 119 } 120 for (i = 0; i < seminfo.semmnu; i++) { 121 struct sem_undo *suptr = SEMU(semu, i); 122 suptr->un_proc = NULL; 123 } 124 semu_list = NULL; 125 exithook_establish(semexit, NULL); 126 } 127 128 static int 129 semrealloc(int newsemmni, int newsemmns, int newsemmnu) 130 { 131 struct semid_ds *new_sema, *old_sema; 132 struct __sem *new_sem; 133 struct sem_undo *new_semu_list, *suptr, *nsuptr; 134 int *new_semu; 135 kcondvar_t *new_semcv; 136 vaddr_t v; 137 int i, j, lsemid, nmnus, sz; 138 139 if (newsemmni < 1 || newsemmns < 1 || newsemmnu < 1) 140 return EINVAL; 141 142 /* Allocate the wired memory for our structures */ 143 sz = ALIGN(newsemmni * sizeof(struct semid_ds)) + 144 ALIGN(newsemmns * sizeof(struct __sem)) + 145 ALIGN(newsemmni * sizeof(kcondvar_t)) + 146 ALIGN(newsemmnu * seminfo.semusz); 147 v = uvm_km_alloc(kernel_map, round_page(sz), 0, 148 UVM_KMF_WIRED|UVM_KMF_ZERO); 149 if (v == 0) 150 return ENOMEM; 151 152 mutex_enter(&semlock); 153 if (sem_realloc_state) { 154 mutex_exit(&semlock); 155 uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED); 156 return EBUSY; 157 } 158 sem_realloc_state = true; 159 if (sem_waiters) { 160 /* 161 * Mark reallocation state, wake-up all waiters, 162 * and wait while they will all exit. 163 */ 164 for (i = 0; i < seminfo.semmni; i++) 165 cv_broadcast(&semcv[i]); 166 while (sem_waiters) 167 cv_wait(&sem_realloc_cv, &semlock); 168 } 169 old_sema = sema; 170 171 /* Get the number of last slot */ 172 lsemid = 0; 173 for (i = 0; i < seminfo.semmni; i++) 174 if (sema[i].sem_perm.mode & SEM_ALLOC) 175 lsemid = i; 176 177 /* Get the number of currently used undo structures */ 178 nmnus = 0; 179 for (i = 0; i < seminfo.semmnu; i++) { 180 suptr = SEMU(semu, i); 181 if (suptr->un_proc == NULL) 182 continue; 183 nmnus++; 184 } 185 186 /* We cannot reallocate less memory than we use */ 187 if (lsemid >= newsemmni || semtot > newsemmns || nmnus > newsemmnu) { 188 mutex_exit(&semlock); 189 uvm_km_free(kernel_map, v, sz, UVM_KMF_WIRED); 190 return EBUSY; 191 } 192 193 new_sema = (void *)v; 194 new_sem = (void *)((uintptr_t)new_sema + 195 ALIGN(newsemmni * sizeof(struct semid_ds))); 196 new_semcv = (void *)((uintptr_t)new_sem + 197 ALIGN(newsemmns * sizeof(struct __sem))); 198 new_semu = (void *)((uintptr_t)new_semcv + 199 ALIGN(newsemmni * sizeof(kcondvar_t))); 200 201 /* Initialize all semaphore identifiers and condvars */ 202 for (i = 0; i < newsemmni; i++) { 203 new_sema[i]._sem_base = 0; 204 new_sema[i].sem_perm.mode = 0; 205 cv_init(&new_semcv[i], "semwait"); 206 } 207 for (i = 0; i < newsemmnu; i++) { 208 nsuptr = SEMU(new_semu, i); 209 nsuptr->un_proc = NULL; 210 } 211 212 /* 213 * Copy all identifiers, semaphores and list of the 214 * undo structures to the new memory allocation. 215 */ 216 j = 0; 217 for (i = 0; i <= lsemid; i++) { 218 if ((sema[i].sem_perm.mode & SEM_ALLOC) == 0) 219 continue; 220 memcpy(&new_sema[i], &sema[i], sizeof(struct semid_ds)); 221 new_sema[i]._sem_base = &new_sem[j]; 222 memcpy(new_sema[i]._sem_base, sema[i]._sem_base, 223 (sizeof(struct __sem) * sema[i].sem_nsems)); 224 j += sema[i].sem_nsems; 225 } 226 KASSERT(j == semtot); 227 228 j = 0; 229 new_semu_list = NULL; 230 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { 231 KASSERT(j < newsemmnu); 232 nsuptr = SEMU(new_semu, j); 233 memcpy(nsuptr, suptr, SEMUSZ); 234 nsuptr->un_next = new_semu_list; 235 new_semu_list = nsuptr; 236 j++; 237 } 238 239 for (i = 0; i < seminfo.semmni; i++) { 240 KASSERT(cv_has_waiters(&semcv[i]) == false); 241 cv_destroy(&semcv[i]); 242 } 243 244 sz = ALIGN(seminfo.semmni * sizeof(struct semid_ds)) + 245 ALIGN(seminfo.semmns * sizeof(struct __sem)) + 246 ALIGN(seminfo.semmni * sizeof(kcondvar_t)) + 247 ALIGN(seminfo.semmnu * seminfo.semusz); 248 249 /* Set the pointers and update the new values */ 250 sema = new_sema; 251 sem = new_sem; 252 semcv = new_semcv; 253 semu = new_semu; 254 semu_list = new_semu_list; 255 256 seminfo.semmni = newsemmni; 257 seminfo.semmns = newsemmns; 258 seminfo.semmnu = newsemmnu; 259 260 /* Reallocation completed - notify all waiters, if any */ 261 sem_realloc_state = false; 262 cv_broadcast(&sem_realloc_cv); 263 mutex_exit(&semlock); 264 265 uvm_km_free(kernel_map, (vaddr_t)old_sema, sz, UVM_KMF_WIRED); 266 return 0; 267 } 268 269 /* 270 * Placebo. 271 */ 272 273 int 274 sys_semconfig(struct lwp *l, const struct sys_semconfig_args *uap, register_t *retval) 275 { 276 277 *retval = 0; 278 return 0; 279 } 280 281 /* 282 * Allocate a new sem_undo structure for a process 283 * (returns ptr to structure or NULL if no more room) 284 */ 285 286 struct sem_undo * 287 semu_alloc(struct proc *p) 288 { 289 int i; 290 struct sem_undo *suptr; 291 struct sem_undo **supptr; 292 int attempt; 293 294 KASSERT(mutex_owned(&semlock)); 295 296 /* 297 * Try twice to allocate something. 298 * (we'll purge any empty structures after the first pass so 299 * two passes are always enough) 300 */ 301 302 for (attempt = 0; attempt < 2; attempt++) { 303 /* 304 * Look for a free structure. 305 * Fill it in and return it if we find one. 306 */ 307 308 for (i = 0; i < seminfo.semmnu; i++) { 309 suptr = SEMU(semu, i); 310 if (suptr->un_proc == NULL) { 311 suptr->un_next = semu_list; 312 semu_list = suptr; 313 suptr->un_cnt = 0; 314 suptr->un_proc = p; 315 return (suptr); 316 } 317 } 318 319 /* 320 * We didn't find a free one, if this is the first attempt 321 * then try to free some structures. 322 */ 323 324 if (attempt == 0) { 325 /* All the structures are in use - try to free some */ 326 int did_something = 0; 327 328 supptr = &semu_list; 329 while ((suptr = *supptr) != NULL) { 330 if (suptr->un_cnt == 0) { 331 suptr->un_proc = NULL; 332 *supptr = suptr->un_next; 333 did_something = 1; 334 } else 335 supptr = &suptr->un_next; 336 } 337 338 /* If we didn't free anything then just give-up */ 339 if (!did_something) 340 return (NULL); 341 } else { 342 /* 343 * The second pass failed even though we freed 344 * something after the first pass! 345 * This is IMPOSSIBLE! 346 */ 347 panic("semu_alloc - second attempt failed"); 348 } 349 } 350 return NULL; 351 } 352 353 /* 354 * Adjust a particular entry for a particular proc 355 */ 356 357 int 358 semundo_adjust(struct proc *p, struct sem_undo **supptr, int semid, int semnum, 359 int adjval) 360 { 361 struct sem_undo *suptr; 362 struct undo *sunptr; 363 int i; 364 365 KASSERT(mutex_owned(&semlock)); 366 367 /* 368 * Look for and remember the sem_undo if the caller doesn't 369 * provide it 370 */ 371 372 suptr = *supptr; 373 if (suptr == NULL) { 374 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) 375 if (suptr->un_proc == p) 376 break; 377 378 if (suptr == NULL) { 379 suptr = semu_alloc(p); 380 if (suptr == NULL) 381 return (ENOSPC); 382 } 383 *supptr = suptr; 384 } 385 386 /* 387 * Look for the requested entry and adjust it (delete if 388 * adjval becomes 0). 389 */ 390 sunptr = &suptr->un_ent[0]; 391 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 392 if (sunptr->un_id != semid || sunptr->un_num != semnum) 393 continue; 394 sunptr->un_adjval += adjval; 395 if (sunptr->un_adjval == 0) { 396 suptr->un_cnt--; 397 if (i < suptr->un_cnt) 398 suptr->un_ent[i] = 399 suptr->un_ent[suptr->un_cnt]; 400 } 401 return (0); 402 } 403 404 /* Didn't find the right entry - create it */ 405 if (suptr->un_cnt == SEMUME) 406 return (EINVAL); 407 408 sunptr = &suptr->un_ent[suptr->un_cnt]; 409 suptr->un_cnt++; 410 sunptr->un_adjval = adjval; 411 sunptr->un_id = semid; 412 sunptr->un_num = semnum; 413 return (0); 414 } 415 416 void 417 semundo_clear(int semid, int semnum) 418 { 419 struct sem_undo *suptr; 420 struct undo *sunptr, *sunend; 421 422 KASSERT(mutex_owned(&semlock)); 423 424 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) 425 for (sunptr = &suptr->un_ent[0], 426 sunend = sunptr + suptr->un_cnt; sunptr < sunend;) { 427 if (sunptr->un_id == semid) { 428 if (semnum == -1 || sunptr->un_num == semnum) { 429 suptr->un_cnt--; 430 sunend--; 431 if (sunptr != sunend) 432 *sunptr = *sunend; 433 if (semnum != -1) 434 break; 435 else 436 continue; 437 } 438 } 439 sunptr++; 440 } 441 } 442 443 int 444 sys_____semctl13(struct lwp *l, const struct sys_____semctl13_args *uap, register_t *retval) 445 { 446 /* { 447 syscallarg(int) semid; 448 syscallarg(int) semnum; 449 syscallarg(int) cmd; 450 syscallarg(union __semun *) arg; 451 } */ 452 struct semid_ds sembuf; 453 int cmd, error; 454 void *pass_arg; 455 union __semun karg; 456 457 cmd = SCARG(uap, cmd); 458 459 pass_arg = get_semctl_arg(cmd, &sembuf, &karg); 460 461 if (pass_arg) { 462 error = copyin(SCARG(uap, arg), &karg, sizeof(karg)); 463 if (error) 464 return error; 465 if (cmd == IPC_SET) { 466 error = copyin(karg.buf, &sembuf, sizeof(sembuf)); 467 if (error) 468 return (error); 469 } 470 } 471 472 error = semctl1(l, SCARG(uap, semid), SCARG(uap, semnum), cmd, 473 pass_arg, retval); 474 475 if (error == 0 && cmd == IPC_STAT) 476 error = copyout(&sembuf, karg.buf, sizeof(sembuf)); 477 478 return (error); 479 } 480 481 int 482 semctl1(struct lwp *l, int semid, int semnum, int cmd, void *v, 483 register_t *retval) 484 { 485 kauth_cred_t cred = l->l_cred; 486 union __semun *arg = v; 487 struct semid_ds *sembuf = v, *semaptr; 488 int i, error, ix; 489 490 SEM_PRINTF(("call to semctl(%d, %d, %d, %p)\n", 491 semid, semnum, cmd, v)); 492 493 mutex_enter(&semlock); 494 495 ix = IPCID_TO_IX(semid); 496 if (ix < 0 || ix >= seminfo.semmni) { 497 mutex_exit(&semlock); 498 return (EINVAL); 499 } 500 501 semaptr = &sema[ix]; 502 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 503 semaptr->sem_perm._seq != IPCID_TO_SEQ(semid)) { 504 mutex_exit(&semlock); 505 return (EINVAL); 506 } 507 508 switch (cmd) { 509 case IPC_RMID: 510 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)) != 0) 511 break; 512 semaptr->sem_perm.cuid = kauth_cred_geteuid(cred); 513 semaptr->sem_perm.uid = kauth_cred_geteuid(cred); 514 semtot -= semaptr->sem_nsems; 515 for (i = semaptr->_sem_base - sem; i < semtot; i++) 516 sem[i] = sem[i + semaptr->sem_nsems]; 517 for (i = 0; i < seminfo.semmni; i++) { 518 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 519 sema[i]._sem_base > semaptr->_sem_base) 520 sema[i]._sem_base -= semaptr->sem_nsems; 521 } 522 semaptr->sem_perm.mode = 0; 523 semundo_clear(ix, -1); 524 cv_broadcast(&semcv[ix]); 525 break; 526 527 case IPC_SET: 528 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M))) 529 break; 530 KASSERT(sembuf != NULL); 531 semaptr->sem_perm.uid = sembuf->sem_perm.uid; 532 semaptr->sem_perm.gid = sembuf->sem_perm.gid; 533 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 534 (sembuf->sem_perm.mode & 0777); 535 semaptr->sem_ctime = time_second; 536 break; 537 538 case IPC_STAT: 539 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 540 break; 541 KASSERT(sembuf != NULL); 542 memcpy(sembuf, semaptr, sizeof(struct semid_ds)); 543 sembuf->sem_perm.mode &= 0777; 544 break; 545 546 case GETNCNT: 547 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 548 break; 549 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 550 error = EINVAL; 551 break; 552 } 553 *retval = semaptr->_sem_base[semnum].semncnt; 554 break; 555 556 case GETPID: 557 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 558 break; 559 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 560 error = EINVAL; 561 break; 562 } 563 *retval = semaptr->_sem_base[semnum].sempid; 564 break; 565 566 case GETVAL: 567 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 568 break; 569 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 570 error = EINVAL; 571 break; 572 } 573 *retval = semaptr->_sem_base[semnum].semval; 574 break; 575 576 case GETALL: 577 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 578 break; 579 KASSERT(arg != NULL); 580 for (i = 0; i < semaptr->sem_nsems; i++) { 581 error = copyout(&semaptr->_sem_base[i].semval, 582 &arg->array[i], sizeof(arg->array[i])); 583 if (error != 0) 584 break; 585 } 586 break; 587 588 case GETZCNT: 589 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 590 break; 591 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 592 error = EINVAL; 593 break; 594 } 595 *retval = semaptr->_sem_base[semnum].semzcnt; 596 break; 597 598 case SETVAL: 599 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) 600 break; 601 if (semnum < 0 || semnum >= semaptr->sem_nsems) { 602 error = EINVAL; 603 break; 604 } 605 KASSERT(arg != NULL); 606 if ((unsigned int)arg->val > seminfo.semvmx) { 607 error = ERANGE; 608 break; 609 } 610 semaptr->_sem_base[semnum].semval = arg->val; 611 semundo_clear(ix, semnum); 612 cv_broadcast(&semcv[ix]); 613 break; 614 615 case SETALL: 616 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) 617 break; 618 KASSERT(arg != NULL); 619 for (i = 0; i < semaptr->sem_nsems; i++) { 620 unsigned short semval; 621 error = copyin(&arg->array[i], &semval, 622 sizeof(arg->array[i])); 623 if (error != 0) 624 break; 625 if ((unsigned int)semval > seminfo.semvmx) { 626 error = ERANGE; 627 break; 628 } 629 semaptr->_sem_base[i].semval = semval; 630 } 631 semundo_clear(ix, -1); 632 cv_broadcast(&semcv[ix]); 633 break; 634 635 default: 636 error = EINVAL; 637 break; 638 } 639 640 mutex_exit(&semlock); 641 return (error); 642 } 643 644 int 645 sys_semget(struct lwp *l, const struct sys_semget_args *uap, register_t *retval) 646 { 647 /* { 648 syscallarg(key_t) key; 649 syscallarg(int) nsems; 650 syscallarg(int) semflg; 651 } */ 652 int semid, error = 0; 653 int key = SCARG(uap, key); 654 int nsems = SCARG(uap, nsems); 655 int semflg = SCARG(uap, semflg); 656 kauth_cred_t cred = l->l_cred; 657 658 SEM_PRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg)); 659 660 mutex_enter(&semlock); 661 662 if (key != IPC_PRIVATE) { 663 for (semid = 0; semid < seminfo.semmni; semid++) { 664 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 665 sema[semid].sem_perm._key == key) 666 break; 667 } 668 if (semid < seminfo.semmni) { 669 SEM_PRINTF(("found public key\n")); 670 if ((error = ipcperm(cred, &sema[semid].sem_perm, 671 semflg & 0700))) 672 goto out; 673 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 674 SEM_PRINTF(("too small\n")); 675 error = EINVAL; 676 goto out; 677 } 678 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 679 SEM_PRINTF(("not exclusive\n")); 680 error = EEXIST; 681 goto out; 682 } 683 goto found; 684 } 685 } 686 687 SEM_PRINTF(("need to allocate the semid_ds\n")); 688 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 689 if (nsems <= 0 || nsems > seminfo.semmsl) { 690 SEM_PRINTF(("nsems out of range (0<%d<=%d)\n", nsems, 691 seminfo.semmsl)); 692 error = EINVAL; 693 goto out; 694 } 695 if (nsems > seminfo.semmns - semtot) { 696 SEM_PRINTF(("not enough semaphores left " 697 "(need %d, got %d)\n", 698 nsems, seminfo.semmns - semtot)); 699 error = ENOSPC; 700 goto out; 701 } 702 for (semid = 0; semid < seminfo.semmni; semid++) { 703 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 704 break; 705 } 706 if (semid == seminfo.semmni) { 707 SEM_PRINTF(("no more semid_ds's available\n")); 708 error = ENOSPC; 709 goto out; 710 } 711 SEM_PRINTF(("semid %d is available\n", semid)); 712 sema[semid].sem_perm._key = key; 713 sema[semid].sem_perm.cuid = kauth_cred_geteuid(cred); 714 sema[semid].sem_perm.uid = kauth_cred_geteuid(cred); 715 sema[semid].sem_perm.cgid = kauth_cred_getegid(cred); 716 sema[semid].sem_perm.gid = kauth_cred_getegid(cred); 717 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 718 sema[semid].sem_perm._seq = 719 (sema[semid].sem_perm._seq + 1) & 0x7fff; 720 sema[semid].sem_nsems = nsems; 721 sema[semid].sem_otime = 0; 722 sema[semid].sem_ctime = time_second; 723 sema[semid]._sem_base = &sem[semtot]; 724 semtot += nsems; 725 memset(sema[semid]._sem_base, 0, 726 sizeof(sema[semid]._sem_base[0]) * nsems); 727 SEM_PRINTF(("sembase = %p, next = %p\n", sema[semid]._sem_base, 728 &sem[semtot])); 729 } else { 730 SEM_PRINTF(("didn't find it and wasn't asked to create it\n")); 731 error = ENOENT; 732 goto out; 733 } 734 735 found: 736 *retval = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 737 out: 738 mutex_exit(&semlock); 739 return (error); 740 } 741 742 #define SMALL_SOPS 8 743 744 int 745 sys_semop(struct lwp *l, const struct sys_semop_args *uap, register_t *retval) 746 { 747 /* { 748 syscallarg(int) semid; 749 syscallarg(struct sembuf *) sops; 750 syscallarg(size_t) nsops; 751 } */ 752 struct proc *p = l->l_proc; 753 int semid = SCARG(uap, semid), seq; 754 size_t nsops = SCARG(uap, nsops); 755 struct sembuf small_sops[SMALL_SOPS]; 756 struct sembuf *sops; 757 struct semid_ds *semaptr; 758 struct sembuf *sopptr = NULL; 759 struct __sem *semptr = NULL; 760 struct sem_undo *suptr = NULL; 761 kauth_cred_t cred = l->l_cred; 762 int i, error; 763 int do_wakeup, do_undos; 764 765 SEM_PRINTF(("call to semop(%d, %p, %zd)\n", semid, SCARG(uap,sops), nsops)); 766 767 if (__predict_false((p->p_flag & PK_SYSVSEM) == 0)) { 768 mutex_enter(p->p_lock); 769 p->p_flag |= PK_SYSVSEM; 770 mutex_exit(p->p_lock); 771 } 772 773 restart: 774 if (nsops <= SMALL_SOPS) { 775 sops = small_sops; 776 } else if (nsops <= seminfo.semopm) { 777 sops = kmem_alloc(nsops * sizeof(*sops), KM_SLEEP); 778 } else { 779 SEM_PRINTF(("too many sops (max=%d, nsops=%zd)\n", 780 seminfo.semopm, nsops)); 781 return (E2BIG); 782 } 783 784 error = copyin(SCARG(uap, sops), sops, nsops * sizeof(sops[0])); 785 if (error) { 786 SEM_PRINTF(("error = %d from copyin(%p, %p, %zd)\n", error, 787 SCARG(uap, sops), &sops, nsops * sizeof(sops[0]))); 788 if (sops != small_sops) 789 kmem_free(sops, nsops * sizeof(*sops)); 790 return error; 791 } 792 793 mutex_enter(&semlock); 794 /* In case of reallocation, we will wait for completion */ 795 while (__predict_false(sem_realloc_state)) 796 cv_wait(&sem_realloc_cv, &semlock); 797 798 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 799 if (semid < 0 || semid >= seminfo.semmni) { 800 error = EINVAL; 801 goto out; 802 } 803 804 semaptr = &sema[semid]; 805 seq = IPCID_TO_SEQ(SCARG(uap, semid)); 806 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 807 semaptr->sem_perm._seq != seq) { 808 error = EINVAL; 809 goto out; 810 } 811 812 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) { 813 SEM_PRINTF(("error = %d from ipaccess\n", error)); 814 goto out; 815 } 816 817 for (i = 0; i < nsops; i++) 818 if (sops[i].sem_num >= semaptr->sem_nsems) { 819 error = EFBIG; 820 goto out; 821 } 822 823 /* 824 * Loop trying to satisfy the vector of requests. 825 * If we reach a point where we must wait, any requests already 826 * performed are rolled back and we go to sleep until some other 827 * process wakes us up. At this point, we start all over again. 828 * 829 * This ensures that from the perspective of other tasks, a set 830 * of requests is atomic (never partially satisfied). 831 */ 832 do_undos = 0; 833 834 for (;;) { 835 do_wakeup = 0; 836 837 for (i = 0; i < nsops; i++) { 838 sopptr = &sops[i]; 839 semptr = &semaptr->_sem_base[sopptr->sem_num]; 840 841 SEM_PRINTF(("semop: semaptr=%p, sem_base=%p, " 842 "semptr=%p, sem[%d]=%d : op=%d, flag=%s\n", 843 semaptr, semaptr->_sem_base, semptr, 844 sopptr->sem_num, semptr->semval, sopptr->sem_op, 845 (sopptr->sem_flg & IPC_NOWAIT) ? 846 "nowait" : "wait")); 847 848 if (sopptr->sem_op < 0) { 849 if ((int)(semptr->semval + 850 sopptr->sem_op) < 0) { 851 SEM_PRINTF(("semop: " 852 "can't do it now\n")); 853 break; 854 } else { 855 semptr->semval += sopptr->sem_op; 856 if (semptr->semval == 0 && 857 semptr->semzcnt > 0) 858 do_wakeup = 1; 859 } 860 if (sopptr->sem_flg & SEM_UNDO) 861 do_undos = 1; 862 } else if (sopptr->sem_op == 0) { 863 if (semptr->semval > 0) { 864 SEM_PRINTF(("semop: not zero now\n")); 865 break; 866 } 867 } else { 868 if (semptr->semncnt > 0) 869 do_wakeup = 1; 870 semptr->semval += sopptr->sem_op; 871 if (sopptr->sem_flg & SEM_UNDO) 872 do_undos = 1; 873 } 874 } 875 876 /* 877 * Did we get through the entire vector? 878 */ 879 if (i >= nsops) 880 goto done; 881 882 /* 883 * No ... rollback anything that we've already done 884 */ 885 SEM_PRINTF(("semop: rollback 0 through %d\n", i - 1)); 886 while (i-- > 0) 887 semaptr->_sem_base[sops[i].sem_num].semval -= 888 sops[i].sem_op; 889 890 /* 891 * If the request that we couldn't satisfy has the 892 * NOWAIT flag set then return with EAGAIN. 893 */ 894 if (sopptr->sem_flg & IPC_NOWAIT) { 895 error = EAGAIN; 896 goto out; 897 } 898 899 if (sopptr->sem_op == 0) 900 semptr->semzcnt++; 901 else 902 semptr->semncnt++; 903 904 sem_waiters++; 905 SEM_PRINTF(("semop: good night!\n")); 906 error = cv_wait_sig(&semcv[semid], &semlock); 907 SEM_PRINTF(("semop: good morning (error=%d)!\n", error)); 908 sem_waiters--; 909 910 /* Notify reallocator, if it is waiting */ 911 cv_broadcast(&sem_realloc_cv); 912 913 /* 914 * Make sure that the semaphore still exists 915 */ 916 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 917 semaptr->sem_perm._seq != seq) { 918 error = EIDRM; 919 goto out; 920 } 921 922 /* 923 * The semaphore is still alive. Readjust the count of 924 * waiting processes. 925 */ 926 semptr = &semaptr->_sem_base[sopptr->sem_num]; 927 if (sopptr->sem_op == 0) 928 semptr->semzcnt--; 929 else 930 semptr->semncnt--; 931 932 /* In case of such state, restart the call */ 933 if (sem_realloc_state) { 934 mutex_exit(&semlock); 935 goto restart; 936 } 937 938 /* Is it really morning, or was our sleep interrupted? */ 939 if (error != 0) { 940 error = EINTR; 941 goto out; 942 } 943 SEM_PRINTF(("semop: good morning!\n")); 944 } 945 946 done: 947 /* 948 * Process any SEM_UNDO requests. 949 */ 950 if (do_undos) { 951 for (i = 0; i < nsops; i++) { 952 /* 953 * We only need to deal with SEM_UNDO's for non-zero 954 * op's. 955 */ 956 int adjval; 957 958 if ((sops[i].sem_flg & SEM_UNDO) == 0) 959 continue; 960 adjval = sops[i].sem_op; 961 if (adjval == 0) 962 continue; 963 error = semundo_adjust(p, &suptr, semid, 964 sops[i].sem_num, -adjval); 965 if (error == 0) 966 continue; 967 968 /* 969 * Oh-Oh! We ran out of either sem_undo's or undo's. 970 * Rollback the adjustments to this point and then 971 * rollback the semaphore ups and down so we can return 972 * with an error with all structures restored. We 973 * rollback the undo's in the exact reverse order that 974 * we applied them. This guarantees that we won't run 975 * out of space as we roll things back out. 976 */ 977 while (i-- > 0) { 978 if ((sops[i].sem_flg & SEM_UNDO) == 0) 979 continue; 980 adjval = sops[i].sem_op; 981 if (adjval == 0) 982 continue; 983 if (semundo_adjust(p, &suptr, semid, 984 sops[i].sem_num, adjval) != 0) 985 panic("semop - can't undo undos"); 986 } 987 988 for (i = 0; i < nsops; i++) 989 semaptr->_sem_base[sops[i].sem_num].semval -= 990 sops[i].sem_op; 991 992 SEM_PRINTF(("error = %d from semundo_adjust\n", error)); 993 goto out; 994 } /* loop through the sops */ 995 } /* if (do_undos) */ 996 997 /* We're definitely done - set the sempid's */ 998 for (i = 0; i < nsops; i++) { 999 sopptr = &sops[i]; 1000 semptr = &semaptr->_sem_base[sopptr->sem_num]; 1001 semptr->sempid = p->p_pid; 1002 } 1003 1004 /* Update sem_otime */ 1005 semaptr->sem_otime = time_second; 1006 1007 /* Do a wakeup if any semaphore was up'd. */ 1008 if (do_wakeup) { 1009 SEM_PRINTF(("semop: doing wakeup\n")); 1010 cv_broadcast(&semcv[semid]); 1011 SEM_PRINTF(("semop: back from wakeup\n")); 1012 } 1013 SEM_PRINTF(("semop: done\n")); 1014 *retval = 0; 1015 1016 out: 1017 mutex_exit(&semlock); 1018 if (sops != small_sops) 1019 kmem_free(sops, nsops * sizeof(*sops)); 1020 return error; 1021 } 1022 1023 /* 1024 * Go through the undo structures for this process and apply the 1025 * adjustments to semaphores. 1026 */ 1027 /*ARGSUSED*/ 1028 void 1029 semexit(struct proc *p, void *v) 1030 { 1031 struct sem_undo *suptr; 1032 struct sem_undo **supptr; 1033 1034 if ((p->p_flag & PK_SYSVSEM) == 0) 1035 return; 1036 1037 mutex_enter(&semlock); 1038 1039 /* 1040 * Go through the chain of undo vectors looking for one 1041 * associated with this process. 1042 */ 1043 1044 for (supptr = &semu_list; (suptr = *supptr) != NULL; 1045 supptr = &suptr->un_next) { 1046 if (suptr->un_proc == p) 1047 break; 1048 } 1049 1050 /* 1051 * If there is no undo vector, skip to the end. 1052 */ 1053 1054 if (suptr == NULL) { 1055 mutex_exit(&semlock); 1056 return; 1057 } 1058 1059 /* 1060 * We now have an undo vector for this process. 1061 */ 1062 1063 SEM_PRINTF(("proc @%p has undo structure with %d entries\n", p, 1064 suptr->un_cnt)); 1065 1066 /* 1067 * If there are any active undo elements then process them. 1068 */ 1069 if (suptr->un_cnt > 0) { 1070 int ix; 1071 1072 for (ix = 0; ix < suptr->un_cnt; ix++) { 1073 int semid = suptr->un_ent[ix].un_id; 1074 int semnum = suptr->un_ent[ix].un_num; 1075 int adjval = suptr->un_ent[ix].un_adjval; 1076 struct semid_ds *semaptr; 1077 1078 semaptr = &sema[semid]; 1079 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 1080 panic("semexit - semid not allocated"); 1081 if (semnum >= semaptr->sem_nsems) 1082 panic("semexit - semnum out of range"); 1083 1084 SEM_PRINTF(("semexit: %p id=%d num=%d(adj=%d) ; " 1085 "sem=%d\n", 1086 suptr->un_proc, suptr->un_ent[ix].un_id, 1087 suptr->un_ent[ix].un_num, 1088 suptr->un_ent[ix].un_adjval, 1089 semaptr->_sem_base[semnum].semval)); 1090 1091 if (adjval < 0 && 1092 semaptr->_sem_base[semnum].semval < -adjval) 1093 semaptr->_sem_base[semnum].semval = 0; 1094 else 1095 semaptr->_sem_base[semnum].semval += adjval; 1096 1097 cv_broadcast(&semcv[semid]); 1098 SEM_PRINTF(("semexit: back from wakeup\n")); 1099 } 1100 } 1101 1102 /* 1103 * Deallocate the undo vector. 1104 */ 1105 SEM_PRINTF(("removing vector\n")); 1106 suptr->un_proc = NULL; 1107 *supptr = suptr->un_next; 1108 mutex_exit(&semlock); 1109 } 1110 1111 /* 1112 * Sysctl initialization and nodes. 1113 */ 1114 1115 static int 1116 sysctl_ipc_semmni(SYSCTLFN_ARGS) 1117 { 1118 int newsize, error; 1119 struct sysctlnode node; 1120 node = *rnode; 1121 node.sysctl_data = &newsize; 1122 1123 newsize = seminfo.semmni; 1124 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1125 if (error || newp == NULL) 1126 return error; 1127 1128 return semrealloc(newsize, seminfo.semmns, seminfo.semmnu); 1129 } 1130 1131 static int 1132 sysctl_ipc_semmns(SYSCTLFN_ARGS) 1133 { 1134 int newsize, error; 1135 struct sysctlnode node; 1136 node = *rnode; 1137 node.sysctl_data = &newsize; 1138 1139 newsize = seminfo.semmns; 1140 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1141 if (error || newp == NULL) 1142 return error; 1143 1144 return semrealloc(seminfo.semmni, newsize, seminfo.semmnu); 1145 } 1146 1147 static int 1148 sysctl_ipc_semmnu(SYSCTLFN_ARGS) 1149 { 1150 int newsize, error; 1151 struct sysctlnode node; 1152 node = *rnode; 1153 node.sysctl_data = &newsize; 1154 1155 newsize = seminfo.semmnu; 1156 error = sysctl_lookup(SYSCTLFN_CALL(&node)); 1157 if (error || newp == NULL) 1158 return error; 1159 1160 return semrealloc(seminfo.semmni, seminfo.semmns, newsize); 1161 } 1162 1163 SYSCTL_SETUP(sysctl_ipc_sem_setup, "sysctl kern.ipc subtree setup") 1164 { 1165 const struct sysctlnode *node = NULL; 1166 1167 sysctl_createv(clog, 0, NULL, NULL, 1168 CTLFLAG_PERMANENT, 1169 CTLTYPE_NODE, "kern", NULL, 1170 NULL, 0, NULL, 0, 1171 CTL_KERN, CTL_EOL); 1172 sysctl_createv(clog, 0, NULL, &node, 1173 CTLFLAG_PERMANENT, 1174 CTLTYPE_NODE, "ipc", 1175 SYSCTL_DESCR("SysV IPC options"), 1176 NULL, 0, NULL, 0, 1177 CTL_KERN, KERN_SYSVIPC, CTL_EOL); 1178 1179 if (node == NULL) 1180 return; 1181 1182 sysctl_createv(clog, 0, &node, NULL, 1183 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 1184 CTLTYPE_INT, "semmni", 1185 SYSCTL_DESCR("Max number of number of semaphore identifiers"), 1186 sysctl_ipc_semmni, 0, &seminfo.semmni, 0, 1187 CTL_CREATE, CTL_EOL); 1188 sysctl_createv(clog, 0, &node, NULL, 1189 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 1190 CTLTYPE_INT, "semmns", 1191 SYSCTL_DESCR("Max number of number of semaphores in system"), 1192 sysctl_ipc_semmns, 0, &seminfo.semmns, 0, 1193 CTL_CREATE, CTL_EOL); 1194 sysctl_createv(clog, 0, &node, NULL, 1195 CTLFLAG_PERMANENT | CTLFLAG_READWRITE, 1196 CTLTYPE_INT, "semmnu", 1197 SYSCTL_DESCR("Max number of undo structures in system"), 1198 sysctl_ipc_semmnu, 0, &seminfo.semmnu, 0, 1199 CTL_CREATE, CTL_EOL); 1200 }
Cache object: 99b50202ef003a0be7fd286f07266af5
[ source navigation ] [ diff markup ] [ identifier search ] [ freetext search ] [ file search ] [ list types ] [ track identifier ]