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sys/kern/sysv_sem.c
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1 /* $NetBSD: sysv_sem.c,v 1.55.10.1 2005/11/05 00:47:00 tron Exp $ */ 2 3 /*- 4 * Copyright (c) 1999 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. 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 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the NetBSD 22 * Foundation, Inc. and its contributors. 23 * 4. Neither the name of The NetBSD Foundation nor the names of its 24 * contributors may be used to endorse or promote products derived 25 * from this software without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 30 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 37 * POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40 /* 41 * Implementation of SVID semaphores 42 * 43 * Author: Daniel Boulet 44 * 45 * This software is provided ``AS IS'' without any warranties of any kind. 46 */ 47 48 #include <sys/cdefs.h> 49 __KERNEL_RCSID(0, "$NetBSD: sysv_sem.c,v 1.55.10.1 2005/11/05 00:47:00 tron Exp $"); 50 51 #define SYSVSEM 52 53 #include <sys/param.h> 54 #include <sys/kernel.h> 55 #include <sys/sem.h> 56 #include <sys/sysctl.h> 57 #include <sys/malloc.h> 58 #include <sys/mount.h> /* XXX for <sys/syscallargs.h> */ 59 #include <sys/sa.h> 60 #include <sys/syscallargs.h> 61 62 static int semtot = 0; 63 struct semid_ds *sema; /* semaphore id pool */ 64 static struct __sem *sem; /* semaphore pool */ 65 static struct sem_undo *semu_list; /* list of active undo structures */ 66 static int *semu; /* undo structure pool */ 67 68 #ifdef SEM_DEBUG 69 #define SEM_PRINTF(a) printf a 70 #else 71 #define SEM_PRINTF(a) 72 #endif 73 74 struct sem_undo *semu_alloc(struct proc *); 75 int semundo_adjust(struct proc *, struct sem_undo **, int, int, int); 76 void semundo_clear(int, int); 77 78 /* 79 * XXXSMP Once we go MP, there needs to be a lock for the semaphore system. 80 * Until then, we're saved by being a non-preemptive kernel. 81 */ 82 83 void 84 seminit() 85 { 86 int i, sz; 87 vaddr_t v; 88 89 /* Allocate pageable memory for our structures */ 90 sz = seminfo.semmni * sizeof(struct semid_ds) + 91 seminfo.semmns * sizeof(struct __sem) + 92 seminfo.semmnu * seminfo.semusz; 93 if ((v = uvm_km_zalloc(kernel_map, round_page(sz))) == 0) 94 panic("sysv_sem: cannot allocate memory"); 95 sema = (void *)v; 96 sem = (void *)(sema + seminfo.semmni); 97 semu = (void *)(sem + seminfo.semmns); 98 99 for (i = 0; i < seminfo.semmni; i++) { 100 sema[i]._sem_base = 0; 101 sema[i].sem_perm.mode = 0; 102 } 103 for (i = 0; i < seminfo.semmnu; i++) { 104 struct sem_undo *suptr = SEMU(i); 105 suptr->un_proc = NULL; 106 } 107 semu_list = NULL; 108 exithook_establish(semexit, NULL); 109 } 110 111 /* 112 * Placebo. 113 */ 114 115 int 116 sys_semconfig(l, v, retval) 117 struct lwp *l; 118 void *v; 119 register_t *retval; 120 { 121 122 *retval = 0; 123 return 0; 124 } 125 126 /* 127 * Allocate a new sem_undo structure for a process 128 * (returns ptr to structure or NULL if no more room) 129 */ 130 131 struct sem_undo * 132 semu_alloc(p) 133 struct proc *p; 134 { 135 int i; 136 struct sem_undo *suptr; 137 struct sem_undo **supptr; 138 int attempt; 139 140 /* 141 * Try twice to allocate something. 142 * (we'll purge any empty structures after the first pass so 143 * two passes are always enough) 144 */ 145 146 for (attempt = 0; attempt < 2; attempt++) { 147 /* 148 * Look for a free structure. 149 * Fill it in and return it if we find one. 150 */ 151 152 for (i = 0; i < seminfo.semmnu; i++) { 153 suptr = SEMU(i); 154 if (suptr->un_proc == NULL) { 155 suptr->un_next = semu_list; 156 semu_list = suptr; 157 suptr->un_cnt = 0; 158 suptr->un_proc = p; 159 return (suptr); 160 } 161 } 162 163 /* 164 * We didn't find a free one, if this is the first attempt 165 * then try to free some structures. 166 */ 167 168 if (attempt == 0) { 169 /* All the structures are in use - try to free some */ 170 int did_something = 0; 171 172 supptr = &semu_list; 173 while ((suptr = *supptr) != NULL) { 174 if (suptr->un_cnt == 0) { 175 suptr->un_proc = NULL; 176 *supptr = suptr->un_next; 177 did_something = 1; 178 } else 179 supptr = &suptr->un_next; 180 } 181 182 /* If we didn't free anything then just give-up */ 183 if (!did_something) 184 return (NULL); 185 } else { 186 /* 187 * The second pass failed even though we freed 188 * something after the first pass! 189 * This is IMPOSSIBLE! 190 */ 191 panic("semu_alloc - second attempt failed"); 192 } 193 } 194 return NULL; 195 } 196 197 /* 198 * Adjust a particular entry for a particular proc 199 */ 200 201 int 202 semundo_adjust(p, supptr, semid, semnum, adjval) 203 struct proc *p; 204 struct sem_undo **supptr; 205 int semid, semnum; 206 int adjval; 207 { 208 struct sem_undo *suptr; 209 struct undo *sunptr; 210 int i; 211 212 /* 213 * Look for and remember the sem_undo if the caller doesn't 214 * provide it 215 */ 216 217 suptr = *supptr; 218 if (suptr == NULL) { 219 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) 220 if (suptr->un_proc == p) 221 break; 222 223 if (suptr == NULL) { 224 suptr = semu_alloc(p); 225 if (suptr == NULL) 226 return (ENOSPC); 227 } 228 *supptr = suptr; 229 } 230 231 /* 232 * Look for the requested entry and adjust it (delete if 233 * adjval becomes 0). 234 */ 235 sunptr = &suptr->un_ent[0]; 236 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 237 if (sunptr->un_id != semid || sunptr->un_num != semnum) 238 continue; 239 sunptr->un_adjval += adjval; 240 if (sunptr->un_adjval == 0) { 241 suptr->un_cnt--; 242 if (i < suptr->un_cnt) 243 suptr->un_ent[i] = 244 suptr->un_ent[suptr->un_cnt]; 245 } 246 return (0); 247 } 248 249 /* Didn't find the right entry - create it */ 250 if (suptr->un_cnt == SEMUME) 251 return (EINVAL); 252 253 sunptr = &suptr->un_ent[suptr->un_cnt]; 254 suptr->un_cnt++; 255 sunptr->un_adjval = adjval; 256 sunptr->un_id = semid; 257 sunptr->un_num = semnum; 258 return (0); 259 } 260 261 void 262 semundo_clear(semid, semnum) 263 int semid, semnum; 264 { 265 struct sem_undo *suptr; 266 struct undo *sunptr, *sunend; 267 268 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) 269 for (sunptr = &suptr->un_ent[0], 270 sunend = sunptr + suptr->un_cnt; sunptr < sunend;) { 271 if (sunptr->un_id == semid) { 272 if (semnum == -1 || sunptr->un_num == semnum) { 273 suptr->un_cnt--; 274 sunend--; 275 if (sunptr != sunend) 276 *sunptr = *sunend; 277 if (semnum != -1) 278 break; 279 else 280 continue; 281 } 282 } 283 sunptr++; 284 } 285 } 286 287 int 288 sys_____semctl13(l, v, retval) 289 struct lwp *l; 290 void *v; 291 register_t *retval; 292 { 293 struct sys_____semctl13_args /* { 294 syscallarg(int) semid; 295 syscallarg(int) semnum; 296 syscallarg(int) cmd; 297 syscallarg(union __semun *) arg; 298 } */ *uap = v; 299 struct proc *p = l->l_proc; 300 struct semid_ds sembuf; 301 int cmd, error; 302 void *pass_arg; 303 union __semun karg; 304 305 cmd = SCARG(uap, cmd); 306 307 switch (cmd) { 308 case IPC_SET: 309 case IPC_STAT: 310 pass_arg = &sembuf; 311 break; 312 313 case GETALL: 314 case SETVAL: 315 case SETALL: 316 pass_arg = &karg; 317 break; 318 default: 319 pass_arg = NULL; 320 break; 321 } 322 323 if (pass_arg) { 324 error = copyin(SCARG(uap, arg), &karg, sizeof(karg)); 325 if (error) 326 return error; 327 if (cmd == IPC_SET) { 328 error = copyin(karg.buf, &sembuf, sizeof(sembuf)); 329 if (error) 330 return (error); 331 } 332 } 333 334 error = semctl1(p, SCARG(uap, semid), SCARG(uap, semnum), cmd, 335 pass_arg, retval); 336 337 if (error == 0 && cmd == IPC_STAT) 338 error = copyout(&sembuf, karg.buf, sizeof(sembuf)); 339 340 return (error); 341 } 342 343 int 344 semctl1(p, semid, semnum, cmd, v, retval) 345 struct proc *p; 346 int semid, semnum, cmd; 347 void *v; 348 register_t *retval; 349 { 350 struct ucred *cred = p->p_ucred; 351 union __semun *arg = v; 352 struct semid_ds *sembuf = v, *semaptr; 353 int i, error, ix; 354 355 SEM_PRINTF(("call to semctl(%d, %d, %d, %p)\n", 356 semid, semnum, cmd, v)); 357 358 ix = IPCID_TO_IX(semid); 359 if (ix < 0 || ix >= seminfo.semmni) 360 return (EINVAL); 361 362 semaptr = &sema[ix]; 363 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 364 semaptr->sem_perm._seq != IPCID_TO_SEQ(semid)) 365 return (EINVAL); 366 367 switch (cmd) { 368 case IPC_RMID: 369 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)) != 0) 370 return (error); 371 semaptr->sem_perm.cuid = cred->cr_uid; 372 semaptr->sem_perm.uid = cred->cr_uid; 373 semtot -= semaptr->sem_nsems; 374 for (i = semaptr->_sem_base - sem; i < semtot; i++) 375 sem[i] = sem[i + semaptr->sem_nsems]; 376 for (i = 0; i < seminfo.semmni; i++) { 377 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 378 sema[i]._sem_base > semaptr->_sem_base) 379 sema[i]._sem_base -= semaptr->sem_nsems; 380 } 381 semaptr->sem_perm.mode = 0; 382 semundo_clear(ix, -1); 383 wakeup(semaptr); 384 break; 385 386 case IPC_SET: 387 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M))) 388 return (error); 389 semaptr->sem_perm.uid = sembuf->sem_perm.uid; 390 semaptr->sem_perm.gid = sembuf->sem_perm.gid; 391 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 392 (sembuf->sem_perm.mode & 0777); 393 semaptr->sem_ctime = time.tv_sec; 394 break; 395 396 case IPC_STAT: 397 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 398 return (error); 399 memcpy(sembuf, semaptr, sizeof(struct semid_ds)); 400 break; 401 402 case GETNCNT: 403 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 404 return (error); 405 if (semnum < 0 || semnum >= semaptr->sem_nsems) 406 return (EINVAL); 407 *retval = semaptr->_sem_base[semnum].semncnt; 408 break; 409 410 case GETPID: 411 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 412 return (error); 413 if (semnum < 0 || semnum >= semaptr->sem_nsems) 414 return (EINVAL); 415 *retval = semaptr->_sem_base[semnum].sempid; 416 break; 417 418 case GETVAL: 419 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 420 return (error); 421 if (semnum < 0 || semnum >= semaptr->sem_nsems) 422 return (EINVAL); 423 *retval = semaptr->_sem_base[semnum].semval; 424 break; 425 426 case GETALL: 427 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 428 return (error); 429 for (i = 0; i < semaptr->sem_nsems; i++) { 430 error = copyout(&semaptr->_sem_base[i].semval, 431 &arg->array[i], sizeof(arg->array[i])); 432 if (error != 0) 433 break; 434 } 435 break; 436 437 case GETZCNT: 438 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 439 return (error); 440 if (semnum < 0 || semnum >= semaptr->sem_nsems) 441 return (EINVAL); 442 *retval = semaptr->_sem_base[semnum].semzcnt; 443 break; 444 445 case SETVAL: 446 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) 447 return (error); 448 if (semnum < 0 || semnum >= semaptr->sem_nsems) 449 return (EINVAL); 450 semaptr->_sem_base[semnum].semval = arg->val; 451 semundo_clear(ix, semnum); 452 wakeup(semaptr); 453 break; 454 455 case SETALL: 456 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) 457 return (error); 458 for (i = 0; i < semaptr->sem_nsems; i++) { 459 error = copyin(&arg->array[i], 460 &semaptr->_sem_base[i].semval, 461 sizeof(arg->array[i])); 462 if (error != 0) 463 break; 464 } 465 semundo_clear(ix, -1); 466 wakeup(semaptr); 467 break; 468 469 default: 470 return (EINVAL); 471 } 472 473 return (error); 474 } 475 476 int 477 sys_semget(l, v, retval) 478 struct lwp *l; 479 void *v; 480 register_t *retval; 481 { 482 struct sys_semget_args /* { 483 syscallarg(key_t) key; 484 syscallarg(int) nsems; 485 syscallarg(int) semflg; 486 } */ *uap = v; 487 int semid, eval; 488 int key = SCARG(uap, key); 489 int nsems = SCARG(uap, nsems); 490 int semflg = SCARG(uap, semflg); 491 struct ucred *cred = l->l_proc->p_ucred; 492 493 SEM_PRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg)); 494 495 if (key != IPC_PRIVATE) { 496 for (semid = 0; semid < seminfo.semmni; semid++) { 497 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 498 sema[semid].sem_perm._key == key) 499 break; 500 } 501 if (semid < seminfo.semmni) { 502 SEM_PRINTF(("found public key\n")); 503 if ((eval = ipcperm(cred, &sema[semid].sem_perm, 504 semflg & 0700))) 505 return (eval); 506 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 507 SEM_PRINTF(("too small\n")); 508 return (EINVAL); 509 } 510 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 511 SEM_PRINTF(("not exclusive\n")); 512 return (EEXIST); 513 } 514 goto found; 515 } 516 } 517 518 SEM_PRINTF(("need to allocate the semid_ds\n")); 519 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 520 if (nsems <= 0 || nsems > seminfo.semmsl) { 521 SEM_PRINTF(("nsems out of range (0<%d<=%d)\n", nsems, 522 seminfo.semmsl)); 523 return (EINVAL); 524 } 525 if (nsems > seminfo.semmns - semtot) { 526 SEM_PRINTF(("not enough semaphores left " 527 "(need %d, got %d)\n", 528 nsems, seminfo.semmns - semtot)); 529 return (ENOSPC); 530 } 531 for (semid = 0; semid < seminfo.semmni; semid++) { 532 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 533 break; 534 } 535 if (semid == seminfo.semmni) { 536 SEM_PRINTF(("no more semid_ds's available\n")); 537 return (ENOSPC); 538 } 539 SEM_PRINTF(("semid %d is available\n", semid)); 540 sema[semid].sem_perm._key = key; 541 sema[semid].sem_perm.cuid = cred->cr_uid; 542 sema[semid].sem_perm.uid = cred->cr_uid; 543 sema[semid].sem_perm.cgid = cred->cr_gid; 544 sema[semid].sem_perm.gid = cred->cr_gid; 545 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 546 sema[semid].sem_perm._seq = 547 (sema[semid].sem_perm._seq + 1) & 0x7fff; 548 sema[semid].sem_nsems = nsems; 549 sema[semid].sem_otime = 0; 550 sema[semid].sem_ctime = time.tv_sec; 551 sema[semid]._sem_base = &sem[semtot]; 552 semtot += nsems; 553 memset(sema[semid]._sem_base, 0, 554 sizeof(sema[semid]._sem_base[0]) * nsems); 555 SEM_PRINTF(("sembase = %p, next = %p\n", sema[semid]._sem_base, 556 &sem[semtot])); 557 } else { 558 SEM_PRINTF(("didn't find it and wasn't asked to create it\n")); 559 return (ENOENT); 560 } 561 562 found: 563 *retval = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 564 return (0); 565 } 566 567 #define SMALL_SOPS 8 568 569 int 570 sys_semop(l, v, retval) 571 struct lwp *l; 572 void *v; 573 register_t *retval; 574 { 575 struct sys_semop_args /* { 576 syscallarg(int) semid; 577 syscallarg(struct sembuf *) sops; 578 syscallarg(size_t) nsops; 579 } */ *uap = v; 580 struct proc *p = l->l_proc; 581 int semid = SCARG(uap, semid), seq; 582 size_t nsops = SCARG(uap, nsops); 583 struct sembuf small_sops[SMALL_SOPS]; 584 struct sembuf *sops; 585 struct semid_ds *semaptr; 586 struct sembuf *sopptr = NULL; 587 struct __sem *semptr = NULL; 588 struct sem_undo *suptr = NULL; 589 struct ucred *cred = p->p_ucred; 590 int i, eval; 591 int do_wakeup, do_undos; 592 593 SEM_PRINTF(("call to semop(%d, %p, %zd)\n", semid, sops, nsops)); 594 595 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 596 if (semid < 0 || semid >= seminfo.semmni) 597 return (EINVAL); 598 599 semaptr = &sema[semid]; 600 seq = IPCID_TO_SEQ(SCARG(uap, semid)); 601 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 602 semaptr->sem_perm._seq != seq) 603 return (EINVAL); 604 605 if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_W))) { 606 SEM_PRINTF(("eval = %d from ipaccess\n", eval)); 607 return (eval); 608 } 609 610 if (nsops <= SMALL_SOPS) { 611 sops = small_sops; 612 } else if (nsops <= seminfo.semopm) { 613 sops = malloc(nsops * sizeof(*sops), M_TEMP, M_WAITOK); 614 } else { 615 SEM_PRINTF(("too many sops (max=%d, nsops=%zd)\n", 616 seminfo.semopm, nsops)); 617 return (E2BIG); 618 } 619 620 if ((eval = copyin(SCARG(uap, sops), 621 sops, nsops * sizeof(sops[0]))) != 0) { 622 SEM_PRINTF(("eval = %d from copyin(%p, %p, %zd)\n", eval, 623 SCARG(uap, sops), &sops, nsops * sizeof(sops[0]))); 624 goto out; 625 } 626 627 for (i = 0; i < nsops; i++) 628 if (sops[i].sem_num >= semaptr->sem_nsems) { 629 eval = EFBIG; 630 goto out; 631 } 632 633 /* 634 * Loop trying to satisfy the vector of requests. 635 * If we reach a point where we must wait, any requests already 636 * performed are rolled back and we go to sleep until some other 637 * process wakes us up. At this point, we start all over again. 638 * 639 * This ensures that from the perspective of other tasks, a set 640 * of requests is atomic (never partially satisfied). 641 */ 642 do_undos = 0; 643 644 for (;;) { 645 do_wakeup = 0; 646 647 for (i = 0; i < nsops; i++) { 648 sopptr = &sops[i]; 649 semptr = &semaptr->_sem_base[sopptr->sem_num]; 650 651 SEM_PRINTF(("semop: semaptr=%p, sem_base=%p, " 652 "semptr=%p, sem[%d]=%d : op=%d, flag=%s\n", 653 semaptr, semaptr->_sem_base, semptr, 654 sopptr->sem_num, semptr->semval, sopptr->sem_op, 655 (sopptr->sem_flg & IPC_NOWAIT) ? 656 "nowait" : "wait")); 657 658 if (sopptr->sem_op < 0) { 659 if ((int)(semptr->semval + 660 sopptr->sem_op) < 0) { 661 SEM_PRINTF(("semop: " 662 "can't do it now\n")); 663 break; 664 } else { 665 semptr->semval += sopptr->sem_op; 666 if (semptr->semval == 0 && 667 semptr->semzcnt > 0) 668 do_wakeup = 1; 669 } 670 if (sopptr->sem_flg & SEM_UNDO) 671 do_undos = 1; 672 } else if (sopptr->sem_op == 0) { 673 if (semptr->semval > 0) { 674 SEM_PRINTF(("semop: not zero now\n")); 675 break; 676 } 677 } else { 678 if (semptr->semncnt > 0) 679 do_wakeup = 1; 680 semptr->semval += sopptr->sem_op; 681 if (sopptr->sem_flg & SEM_UNDO) 682 do_undos = 1; 683 } 684 } 685 686 /* 687 * Did we get through the entire vector? 688 */ 689 if (i >= nsops) 690 goto done; 691 692 /* 693 * No ... rollback anything that we've already done 694 */ 695 SEM_PRINTF(("semop: rollback 0 through %d\n", i - 1)); 696 while (i-- > 0) 697 semaptr->_sem_base[sops[i].sem_num].semval -= 698 sops[i].sem_op; 699 700 /* 701 * If the request that we couldn't satisfy has the 702 * NOWAIT flag set then return with EAGAIN. 703 */ 704 if (sopptr->sem_flg & IPC_NOWAIT) { 705 eval = EAGAIN; 706 goto out; 707 } 708 709 if (sopptr->sem_op == 0) 710 semptr->semzcnt++; 711 else 712 semptr->semncnt++; 713 714 SEM_PRINTF(("semop: good night!\n")); 715 eval = tsleep((caddr_t)semaptr, (PZERO - 4) | PCATCH, 716 "semwait", 0); 717 SEM_PRINTF(("semop: good morning (eval=%d)!\n", eval)); 718 719 /* 720 * Make sure that the semaphore still exists 721 */ 722 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 723 semaptr->sem_perm._seq != seq) { 724 eval = EIDRM; 725 goto out; 726 } 727 728 /* 729 * The semaphore is still alive. Readjust the count of 730 * waiting processes. 731 */ 732 semptr = &semaptr->_sem_base[sopptr->sem_num]; 733 if (sopptr->sem_op == 0) 734 semptr->semzcnt--; 735 else 736 semptr->semncnt--; 737 /* 738 * Is it really morning, or was our sleep interrupted? 739 * (Delayed check of tsleep() return code because we 740 * need to decrement sem[nz]cnt either way.) 741 */ 742 if (eval != 0) { 743 eval = EINTR; 744 goto out; 745 } 746 SEM_PRINTF(("semop: good morning!\n")); 747 } 748 749 done: 750 /* 751 * Process any SEM_UNDO requests. 752 */ 753 if (do_undos) { 754 for (i = 0; i < nsops; i++) { 755 /* 756 * We only need to deal with SEM_UNDO's for non-zero 757 * op's. 758 */ 759 int adjval; 760 761 if ((sops[i].sem_flg & SEM_UNDO) == 0) 762 continue; 763 adjval = sops[i].sem_op; 764 if (adjval == 0) 765 continue; 766 eval = semundo_adjust(p, &suptr, semid, 767 sops[i].sem_num, -adjval); 768 if (eval == 0) 769 continue; 770 771 /* 772 * Oh-Oh! We ran out of either sem_undo's or undo's. 773 * Rollback the adjustments to this point and then 774 * rollback the semaphore ups and down so we can return 775 * with an error with all structures restored. We 776 * rollback the undo's in the exact reverse order that 777 * we applied them. This guarantees that we won't run 778 * out of space as we roll things back out. 779 */ 780 while (i-- > 0) { 781 if ((sops[i].sem_flg & SEM_UNDO) == 0) 782 continue; 783 adjval = sops[i].sem_op; 784 if (adjval == 0) 785 continue; 786 if (semundo_adjust(p, &suptr, semid, 787 sops[i].sem_num, adjval) != 0) 788 panic("semop - can't undo undos"); 789 } 790 791 for (i = 0; i < nsops; i++) 792 semaptr->_sem_base[sops[i].sem_num].semval -= 793 sops[i].sem_op; 794 795 SEM_PRINTF(("eval = %d from semundo_adjust\n", eval)); 796 goto out; 797 } /* loop through the sops */ 798 } /* if (do_undos) */ 799 800 /* We're definitely done - set the sempid's */ 801 for (i = 0; i < nsops; i++) { 802 sopptr = &sops[i]; 803 semptr = &semaptr->_sem_base[sopptr->sem_num]; 804 semptr->sempid = p->p_pid; 805 } 806 807 /* Update sem_otime */ 808 semaptr->sem_otime = time.tv_sec; 809 810 /* Do a wakeup if any semaphore was up'd. */ 811 if (do_wakeup) { 812 SEM_PRINTF(("semop: doing wakeup\n")); 813 #ifdef SEM_WAKEUP 814 sem_wakeup((caddr_t)semaptr); 815 #else 816 wakeup((caddr_t)semaptr); 817 #endif 818 SEM_PRINTF(("semop: back from wakeup\n")); 819 } 820 SEM_PRINTF(("semop: done\n")); 821 *retval = 0; 822 823 out: 824 if (sops != small_sops) { 825 free(sops, M_TEMP); 826 } 827 return eval; 828 } 829 830 /* 831 * Go through the undo structures for this process and apply the 832 * adjustments to semaphores. 833 */ 834 /*ARGSUSED*/ 835 void 836 semexit(p, v) 837 struct proc *p; 838 void *v; 839 { 840 struct sem_undo *suptr; 841 struct sem_undo **supptr; 842 843 /* 844 * Go through the chain of undo vectors looking for one 845 * associated with this process. 846 */ 847 848 for (supptr = &semu_list; (suptr = *supptr) != NULL; 849 supptr = &suptr->un_next) { 850 if (suptr->un_proc == p) 851 break; 852 } 853 854 /* 855 * If there is no undo vector, skip to the end. 856 */ 857 858 if (suptr == NULL) 859 return; 860 861 /* 862 * We now have an undo vector for this process. 863 */ 864 865 SEM_PRINTF(("proc @%p has undo structure with %d entries\n", p, 866 suptr->un_cnt)); 867 868 /* 869 * If there are any active undo elements then process them. 870 */ 871 if (suptr->un_cnt > 0) { 872 int ix; 873 874 for (ix = 0; ix < suptr->un_cnt; ix++) { 875 int semid = suptr->un_ent[ix].un_id; 876 int semnum = suptr->un_ent[ix].un_num; 877 int adjval = suptr->un_ent[ix].un_adjval; 878 struct semid_ds *semaptr; 879 880 semaptr = &sema[semid]; 881 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 882 panic("semexit - semid not allocated"); 883 if (semnum >= semaptr->sem_nsems) 884 panic("semexit - semnum out of range"); 885 886 SEM_PRINTF(("semexit: %p id=%d num=%d(adj=%d) ; " 887 "sem=%d\n", 888 suptr->un_proc, suptr->un_ent[ix].un_id, 889 suptr->un_ent[ix].un_num, 890 suptr->un_ent[ix].un_adjval, 891 semaptr->_sem_base[semnum].semval)); 892 893 if (adjval < 0 && 894 semaptr->_sem_base[semnum].semval < -adjval) 895 semaptr->_sem_base[semnum].semval = 0; 896 else 897 semaptr->_sem_base[semnum].semval += adjval; 898 899 #ifdef SEM_WAKEUP 900 sem_wakeup((caddr_t)semaptr); 901 #else 902 wakeup((caddr_t)semaptr); 903 #endif 904 SEM_PRINTF(("semexit: back from wakeup\n")); 905 } 906 } 907 908 /* 909 * Deallocate the undo vector. 910 */ 911 SEM_PRINTF(("removing vector\n")); 912 suptr->un_proc = NULL; 913 *supptr = suptr->un_next; 914 }
Cache object: e3372f58a519fe61ffc0bbd9bd68ebe7
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