1 /* $NetBSD: sysv_sem.c,v 1.43 2002/03/05 23:28:58 nathanw 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 1.43 2002/03/05 23:28:58 nathanw 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/mount.h> /* XXX for <sys/syscallargs.h> */ 58 #include <sys/syscallargs.h> 59 60 int semtot = 0; 61 struct semid_ds *sema; /* semaphore id pool */ 62 struct __sem *sem; /* semaphore pool */ 63 struct sem_undo *semu_list; /* list of active undo structures */ 64 int *semu; /* undo structure pool */ 65 66 #ifdef SEM_DEBUG 67 #define SEM_PRINTF(a) printf a 68 #else 69 #define SEM_PRINTF(a) 70 #endif 71 72 struct sem_undo *semu_alloc __P((struct proc *)); 73 int semundo_adjust __P((struct proc *, struct sem_undo **, int, int, int)); 74 void semundo_clear __P((int, int)); 75 76 /* 77 * XXXSMP Once we go MP, there needs to be a lock for the semaphore system. 78 * Until then, we're saved by being a non-preemptive kernel. 79 */ 80 81 void 82 seminit() 83 { 84 int i; 85 86 if (sema == NULL) 87 panic("sema is NULL"); 88 if (semu == NULL) 89 panic("semu is NULL"); 90 91 for (i = 0; i < seminfo.semmni; i++) { 92 sema[i]._sem_base = 0; 93 sema[i].sem_perm.mode = 0; 94 } 95 for (i = 0; i < seminfo.semmnu; i++) { 96 struct sem_undo *suptr = SEMU(i); 97 suptr->un_proc = NULL; 98 } 99 semu_list = NULL; 100 } 101 102 /* 103 * Placebo. 104 */ 105 106 int 107 sys_semconfig(p, v, retval) 108 struct proc *p; 109 void *v; 110 register_t *retval; 111 { 112 *retval = 0; 113 return 0; 114 } 115 116 /* 117 * Allocate a new sem_undo structure for a process 118 * (returns ptr to structure or NULL if no more room) 119 */ 120 121 struct sem_undo * 122 semu_alloc(p) 123 struct proc *p; 124 { 125 int i; 126 struct sem_undo *suptr; 127 struct sem_undo **supptr; 128 int attempt; 129 130 /* 131 * Try twice to allocate something. 132 * (we'll purge any empty structures after the first pass so 133 * two passes are always enough) 134 */ 135 136 for (attempt = 0; attempt < 2; attempt++) { 137 /* 138 * Look for a free structure. 139 * Fill it in and return it if we find one. 140 */ 141 142 for (i = 0; i < seminfo.semmnu; i++) { 143 suptr = SEMU(i); 144 if (suptr->un_proc == NULL) { 145 suptr->un_next = semu_list; 146 semu_list = suptr; 147 suptr->un_cnt = 0; 148 suptr->un_proc = p; 149 return(suptr); 150 } 151 } 152 153 /* 154 * We didn't find a free one, if this is the first attempt 155 * then try to free some structures. 156 */ 157 158 if (attempt == 0) { 159 /* All the structures are in use - try to free some */ 160 int did_something = 0; 161 162 supptr = &semu_list; 163 while ((suptr = *supptr) != NULL) { 164 if (suptr->un_cnt == 0) { 165 suptr->un_proc = NULL; 166 *supptr = suptr->un_next; 167 did_something = 1; 168 } else 169 supptr = &(suptr->un_next); 170 } 171 172 /* If we didn't free anything then just give-up */ 173 if (!did_something) 174 return(NULL); 175 } else { 176 /* 177 * The second pass failed even though we freed 178 * something after the first pass! 179 * This is IMPOSSIBLE! 180 */ 181 panic("semu_alloc - second attempt failed"); 182 } 183 } 184 return NULL; 185 } 186 187 /* 188 * Adjust a particular entry for a particular proc 189 */ 190 191 int 192 semundo_adjust(p, supptr, semid, semnum, adjval) 193 struct proc *p; 194 struct sem_undo **supptr; 195 int semid, semnum; 196 int adjval; 197 { 198 struct sem_undo *suptr; 199 struct undo *sunptr; 200 int i; 201 202 /* Look for and remember the sem_undo if the caller doesn't provide 203 it */ 204 205 suptr = *supptr; 206 if (suptr == NULL) { 207 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { 208 if (suptr->un_proc == p) { 209 *supptr = suptr; 210 break; 211 } 212 } 213 if (suptr == NULL) { 214 if (adjval == 0) 215 return(0); 216 suptr = semu_alloc(p); 217 if (suptr == NULL) 218 return(ENOSPC); 219 *supptr = suptr; 220 } 221 } 222 223 /* 224 * Look for the requested entry and adjust it (delete if adjval becomes 225 * 0). 226 */ 227 sunptr = &suptr->un_ent[0]; 228 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 229 if (sunptr->un_id != semid || sunptr->un_num != semnum) 230 continue; 231 if (adjval == 0) 232 sunptr->un_adjval = 0; 233 else 234 sunptr->un_adjval += adjval; 235 if (sunptr->un_adjval == 0) { 236 suptr->un_cnt--; 237 if (i < suptr->un_cnt) 238 suptr->un_ent[i] = 239 suptr->un_ent[suptr->un_cnt]; 240 } 241 return(0); 242 } 243 244 /* Didn't find the right entry - create it */ 245 if (adjval == 0) 246 return(0); 247 if (suptr->un_cnt == SEMUME) 248 return(EINVAL); 249 250 sunptr = &suptr->un_ent[suptr->un_cnt]; 251 suptr->un_cnt++; 252 sunptr->un_adjval = adjval; 253 sunptr->un_id = semid; 254 sunptr->un_num = semnum; 255 return(0); 256 } 257 258 void 259 semundo_clear(semid, semnum) 260 int semid, semnum; 261 { 262 struct sem_undo *suptr; 263 264 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { 265 struct undo *sunptr; 266 int i; 267 268 sunptr = &suptr->un_ent[0]; 269 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 270 if (sunptr->un_id == semid) { 271 if (semnum == -1 || sunptr->un_num == semnum) { 272 suptr->un_cnt--; 273 if (i < suptr->un_cnt) { 274 suptr->un_ent[i] = 275 suptr->un_ent[suptr->un_cnt]; 276 i--, sunptr--; 277 } 278 } 279 if (semnum != -1) 280 break; 281 } 282 } 283 } 284 } 285 286 int 287 sys_____semctl13(p, v, retval) 288 struct proc *p; 289 void *v; 290 register_t *retval; 291 { 292 struct sys_____semctl13_args /* { 293 syscallarg(int) semid; 294 syscallarg(int) semnum; 295 syscallarg(int) cmd; 296 syscallarg(union __semun *) arg; 297 } */ *uap = v; 298 struct semid_ds sembuf; 299 int cmd, error; 300 void *pass_arg; 301 union __semun karg; 302 303 cmd = SCARG(uap, cmd); 304 305 switch (cmd) { 306 case IPC_SET: 307 case IPC_STAT: 308 pass_arg = &sembuf; 309 break; 310 311 case GETALL: 312 case SETVAL: 313 case SETALL: 314 pass_arg = &karg; 315 break; 316 default: 317 pass_arg = NULL; 318 break; 319 } 320 321 if (pass_arg) { 322 error = copyin(SCARG(uap, arg), &karg, sizeof(karg)); 323 if (error) 324 return error; 325 if (cmd == IPC_SET) { 326 error = copyin(karg.buf, &sembuf, sizeof(sembuf)); 327 if (error) 328 return (error); 329 } 330 } 331 332 error = semctl1(p, SCARG(uap, semid), SCARG(uap, semnum), cmd, 333 pass_arg, retval); 334 335 if (error == 0 && cmd == IPC_STAT) 336 error = copyout(&sembuf, karg.buf, sizeof(sembuf)); 337 338 return (error); 339 } 340 341 int 342 semctl1(p, semid, semnum, cmd, v, retval) 343 struct proc *p; 344 int semid, semnum, cmd; 345 void *v; 346 register_t *retval; 347 { 348 struct ucred *cred = p->p_ucred; 349 union __semun *arg = v; 350 struct semid_ds *sembuf = v, *semaptr; 351 int i, error, ix; 352 353 SEM_PRINTF(("call to semctl(%d, %d, %d, %p)\n", 354 semid, semnum, cmd, v)); 355 356 ix = IPCID_TO_IX(semid); 357 if (ix < 0 || ix >= seminfo.semmsl) 358 return (EINVAL); 359 360 semaptr = &sema[ix]; 361 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 362 semaptr->sem_perm._seq != IPCID_TO_SEQ(semid)) 363 return (EINVAL); 364 365 switch (cmd) { 366 case IPC_RMID: 367 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)) != 0) 368 return (error); 369 semaptr->sem_perm.cuid = cred->cr_uid; 370 semaptr->sem_perm.uid = cred->cr_uid; 371 semtot -= semaptr->sem_nsems; 372 for (i = semaptr->_sem_base - sem; i < semtot; i++) 373 sem[i] = sem[i + semaptr->sem_nsems]; 374 for (i = 0; i < seminfo.semmni; i++) { 375 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 376 sema[i]._sem_base > semaptr->_sem_base) 377 sema[i]._sem_base -= semaptr->sem_nsems; 378 } 379 semaptr->sem_perm.mode = 0; 380 semundo_clear(ix, -1); 381 wakeup(semaptr); 382 break; 383 384 case IPC_SET: 385 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M))) 386 return (error); 387 semaptr->sem_perm.uid = sembuf->sem_perm.uid; 388 semaptr->sem_perm.gid = sembuf->sem_perm.gid; 389 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 390 (sembuf->sem_perm.mode & 0777); 391 semaptr->sem_ctime = time.tv_sec; 392 break; 393 394 case IPC_STAT: 395 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 396 return (error); 397 memcpy(sembuf, semaptr, sizeof(struct semid_ds)); 398 break; 399 400 case GETNCNT: 401 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 402 return (error); 403 if (semnum < 0 || semnum >= semaptr->sem_nsems) 404 return (EINVAL); 405 *retval = semaptr->_sem_base[semnum].semncnt; 406 break; 407 408 case GETPID: 409 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 410 return (error); 411 if (semnum < 0 || semnum >= semaptr->sem_nsems) 412 return (EINVAL); 413 *retval = semaptr->_sem_base[semnum].sempid; 414 break; 415 416 case GETVAL: 417 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 418 return (error); 419 if (semnum < 0 || semnum >= semaptr->sem_nsems) 420 return (EINVAL); 421 *retval = semaptr->_sem_base[semnum].semval; 422 break; 423 424 case GETALL: 425 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 426 return (error); 427 for (i = 0; i < semaptr->sem_nsems; i++) { 428 error = copyout(&semaptr->_sem_base[i].semval, 429 &arg->array[i], sizeof(arg->array[i])); 430 if (error != 0) 431 break; 432 } 433 break; 434 435 case GETZCNT: 436 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 437 return (error); 438 if (semnum < 0 || semnum >= semaptr->sem_nsems) 439 return (EINVAL); 440 *retval = semaptr->_sem_base[semnum].semzcnt; 441 break; 442 443 case SETVAL: 444 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) 445 return (error); 446 if (semnum < 0 || semnum >= semaptr->sem_nsems) 447 return (EINVAL); 448 semaptr->_sem_base[semnum].semval = arg->val; 449 semundo_clear(ix, semnum); 450 wakeup(semaptr); 451 break; 452 453 case SETALL: 454 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) 455 return (error); 456 for (i = 0; i < semaptr->sem_nsems; i++) { 457 error = copyin(&arg->array[i], 458 &semaptr->_sem_base[i].semval, 459 sizeof(arg->array[i])); 460 if (error != 0) 461 break; 462 } 463 semundo_clear(ix, -1); 464 wakeup(semaptr); 465 break; 466 467 default: 468 return (EINVAL); 469 } 470 471 return (error); 472 } 473 474 int 475 sys_semget(p, v, retval) 476 struct proc *p; 477 void *v; 478 register_t *retval; 479 { 480 struct sys_semget_args /* { 481 syscallarg(key_t) key; 482 syscallarg(int) nsems; 483 syscallarg(int) semflg; 484 } */ *uap = v; 485 int semid, eval; 486 int key = SCARG(uap, key); 487 int nsems = SCARG(uap, nsems); 488 int semflg = SCARG(uap, semflg); 489 struct ucred *cred = p->p_ucred; 490 491 SEM_PRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg)); 492 493 if (key != IPC_PRIVATE) { 494 for (semid = 0; semid < seminfo.semmni; semid++) { 495 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 496 sema[semid].sem_perm._key == key) 497 break; 498 } 499 if (semid < seminfo.semmni) { 500 SEM_PRINTF(("found public key\n")); 501 if ((eval = ipcperm(cred, &sema[semid].sem_perm, 502 semflg & 0700))) 503 return(eval); 504 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 505 SEM_PRINTF(("too small\n")); 506 return(EINVAL); 507 } 508 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 509 SEM_PRINTF(("not exclusive\n")); 510 return(EEXIST); 511 } 512 goto found; 513 } 514 } 515 516 SEM_PRINTF(("need to allocate the semid_ds\n")); 517 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 518 if (nsems <= 0 || nsems > seminfo.semmsl) { 519 SEM_PRINTF(("nsems out of range (0<%d<=%d)\n", nsems, 520 seminfo.semmsl)); 521 return(EINVAL); 522 } 523 if (nsems > seminfo.semmns - semtot) { 524 SEM_PRINTF(("not enough semaphores left (need %d, got %d)\n", 525 nsems, seminfo.semmns - semtot)); 526 return(ENOSPC); 527 } 528 for (semid = 0; semid < seminfo.semmni; semid++) { 529 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 530 break; 531 } 532 if (semid == seminfo.semmni) { 533 SEM_PRINTF(("no more semid_ds's available\n")); 534 return(ENOSPC); 535 } 536 SEM_PRINTF(("semid %d is available\n", semid)); 537 sema[semid].sem_perm._key = key; 538 sema[semid].sem_perm.cuid = cred->cr_uid; 539 sema[semid].sem_perm.uid = cred->cr_uid; 540 sema[semid].sem_perm.cgid = cred->cr_gid; 541 sema[semid].sem_perm.gid = cred->cr_gid; 542 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 543 sema[semid].sem_perm._seq = 544 (sema[semid].sem_perm._seq + 1) & 0x7fff; 545 sema[semid].sem_nsems = nsems; 546 sema[semid].sem_otime = 0; 547 sema[semid].sem_ctime = time.tv_sec; 548 sema[semid]._sem_base = &sem[semtot]; 549 semtot += nsems; 550 memset(sema[semid]._sem_base, 0, 551 sizeof(sema[semid]._sem_base[0])*nsems); 552 SEM_PRINTF(("sembase = %p, next = %p\n", sema[semid]._sem_base, 553 &sem[semtot])); 554 } else { 555 SEM_PRINTF(("didn't find it and wasn't asked to create it\n")); 556 return(ENOENT); 557 } 558 559 found: 560 *retval = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 561 return(0); 562 } 563 564 int 565 sys_semop(p, v, retval) 566 struct proc *p; 567 void *v; 568 register_t *retval; 569 { 570 struct sys_semop_args /* { 571 syscallarg(int) semid; 572 syscallarg(struct sembuf *) sops; 573 syscallarg(size_t) nsops; 574 } */ *uap = v; 575 int semid = SCARG(uap, semid); 576 size_t nsops = SCARG(uap, nsops); 577 struct sembuf sops[MAX_SOPS]; 578 struct semid_ds *semaptr; 579 struct sembuf *sopptr = NULL; 580 struct __sem *semptr = NULL; 581 struct sem_undo *suptr = NULL; 582 struct ucred *cred = p->p_ucred; 583 int i, j, eval; 584 int do_wakeup, do_undos; 585 586 SEM_PRINTF(("call to semop(%d, %p, %lld)\n", semid, sops, 587 (long long)nsops)); 588 589 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 590 591 if (semid < 0 || semid >= seminfo.semmsl) 592 return(EINVAL); 593 594 semaptr = &sema[semid]; 595 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 596 semaptr->sem_perm._seq != IPCID_TO_SEQ(SCARG(uap, semid))) 597 return(EINVAL); 598 599 if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_W))) { 600 SEM_PRINTF(("eval = %d from ipaccess\n", eval)); 601 return(eval); 602 } 603 604 if (nsops > MAX_SOPS) { 605 SEM_PRINTF(("too many sops (max=%d, nsops=%lld)\n", MAX_SOPS, 606 (long long)nsops)); 607 return(E2BIG); 608 } 609 610 if ((eval = copyin(SCARG(uap, sops), sops, nsops * sizeof(sops[0]))) 611 != 0) { 612 SEM_PRINTF(("eval = %d from copyin(%p, %p, %lld)\n", eval, 613 SCARG(uap, sops), &sops, 614 (long long)(nsops * sizeof(sops[0])))); 615 return(eval); 616 } 617 618 /* 619 * Loop trying to satisfy the vector of requests. 620 * If we reach a point where we must wait, any requests already 621 * performed are rolled back and we go to sleep until some other 622 * process wakes us up. At this point, we start all over again. 623 * 624 * This ensures that from the perspective of other tasks, a set 625 * of requests is atomic (never partially satisfied). 626 */ 627 do_undos = 0; 628 629 for (;;) { 630 do_wakeup = 0; 631 632 for (i = 0; i < nsops; i++) { 633 sopptr = &sops[i]; 634 635 if (sopptr->sem_num >= semaptr->sem_nsems) 636 return(EFBIG); 637 638 semptr = &semaptr->_sem_base[sopptr->sem_num]; 639 640 SEM_PRINTF(("semop: semaptr=%p, sem_base=%p, semptr=%p, sem[%d]=%d : op=%d, flag=%s\n", 641 semaptr, semaptr->_sem_base, semptr, 642 sopptr->sem_num, semptr->semval, sopptr->sem_op, 643 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait")); 644 645 if (sopptr->sem_op < 0) { 646 if ((int)(semptr->semval + 647 sopptr->sem_op) < 0) { 648 SEM_PRINTF(("semop: can't do it now\n")); 649 break; 650 } else { 651 semptr->semval += sopptr->sem_op; 652 if (semptr->semval == 0 && 653 semptr->semzcnt > 0) 654 do_wakeup = 1; 655 } 656 if (sopptr->sem_flg & SEM_UNDO) 657 do_undos = 1; 658 } else if (sopptr->sem_op == 0) { 659 if (semptr->semval > 0) { 660 SEM_PRINTF(("semop: not zero now\n")); 661 break; 662 } 663 } else { 664 if (semptr->semncnt > 0) 665 do_wakeup = 1; 666 semptr->semval += sopptr->sem_op; 667 if (sopptr->sem_flg & SEM_UNDO) 668 do_undos = 1; 669 } 670 } 671 672 /* 673 * Did we get through the entire vector? 674 */ 675 if (i >= nsops) 676 goto done; 677 678 /* 679 * No ... rollback anything that we've already done 680 */ 681 SEM_PRINTF(("semop: rollback 0 through %d\n", i-1)); 682 for (j = 0; j < i; j++) 683 semaptr->_sem_base[sops[j].sem_num].semval -= 684 sops[j].sem_op; 685 686 /* 687 * If the request that we couldn't satisfy has the 688 * NOWAIT flag set then return with EAGAIN. 689 */ 690 if (sopptr->sem_flg & IPC_NOWAIT) 691 return(EAGAIN); 692 693 if (sopptr->sem_op == 0) 694 semptr->semzcnt++; 695 else 696 semptr->semncnt++; 697 698 SEM_PRINTF(("semop: good night!\n")); 699 eval = tsleep((caddr_t)semaptr, (PZERO - 4) | PCATCH, 700 "semwait", 0); 701 SEM_PRINTF(("semop: good morning (eval=%d)!\n", eval)); 702 703 suptr = NULL; /* sem_undo may have been reallocated */ 704 705 if (eval != 0) 706 return(EINTR); 707 SEM_PRINTF(("semop: good morning!\n")); 708 709 /* 710 * Make sure that the semaphore still exists 711 */ 712 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 713 semaptr->sem_perm._seq != IPCID_TO_SEQ(SCARG(uap, semid))) { 714 /* The man page says to return EIDRM. */ 715 /* Unfortunately, BSD doesn't define that code! */ 716 #ifdef EIDRM 717 return(EIDRM); 718 #else 719 return(EINVAL); 720 #endif 721 } 722 723 /* 724 * The semaphore is still alive. Readjust the count of 725 * waiting processes. 726 */ 727 if (sopptr->sem_op == 0) 728 semptr->semzcnt--; 729 else 730 semptr->semncnt--; 731 } 732 733 done: 734 /* 735 * Process any SEM_UNDO requests. 736 */ 737 if (do_undos) { 738 for (i = 0; i < nsops; i++) { 739 /* 740 * We only need to deal with SEM_UNDO's for non-zero 741 * op's. 742 */ 743 int adjval; 744 745 if ((sops[i].sem_flg & SEM_UNDO) == 0) 746 continue; 747 adjval = sops[i].sem_op; 748 if (adjval == 0) 749 continue; 750 eval = semundo_adjust(p, &suptr, semid, 751 sops[i].sem_num, -adjval); 752 if (eval == 0) 753 continue; 754 755 /* 756 * Oh-Oh! We ran out of either sem_undo's or undo's. 757 * Rollback the adjustments to this point and then 758 * rollback the semaphore ups and down so we can return 759 * with an error with all structures restored. We 760 * rollback the undo's in the exact reverse order that 761 * we applied them. This guarantees that we won't run 762 * out of space as we roll things back out. 763 */ 764 for (j = i - 1; j >= 0; j--) { 765 if ((sops[j].sem_flg & SEM_UNDO) == 0) 766 continue; 767 adjval = sops[j].sem_op; 768 if (adjval == 0) 769 continue; 770 if (semundo_adjust(p, &suptr, semid, 771 sops[j].sem_num, adjval) != 0) 772 panic("semop - can't undo undos"); 773 } 774 775 for (j = 0; j < nsops; j++) 776 semaptr->_sem_base[sops[j].sem_num].semval -= 777 sops[j].sem_op; 778 779 SEM_PRINTF(("eval = %d from semundo_adjust\n", eval)); 780 return(eval); 781 } /* loop through the sops */ 782 } /* if (do_undos) */ 783 784 /* We're definitely done - set the sempid's */ 785 for (i = 0; i < nsops; i++) { 786 sopptr = &sops[i]; 787 semptr = &semaptr->_sem_base[sopptr->sem_num]; 788 semptr->sempid = p->p_pid; 789 } 790 791 /* Do a wakeup if any semaphore was up'd. */ 792 if (do_wakeup) { 793 SEM_PRINTF(("semop: doing wakeup\n")); 794 #ifdef SEM_WAKEUP 795 sem_wakeup((caddr_t)semaptr); 796 #else 797 wakeup((caddr_t)semaptr); 798 #endif 799 SEM_PRINTF(("semop: back from wakeup\n")); 800 } 801 SEM_PRINTF(("semop: done\n")); 802 *retval = 0; 803 return(0); 804 } 805 806 /* 807 * Go through the undo structures for this process and apply the adjustments to 808 * semaphores. 809 */ 810 void 811 semexit(p) 812 struct proc *p; 813 { 814 struct sem_undo *suptr; 815 struct sem_undo **supptr; 816 817 /* 818 * Go through the chain of undo vectors looking for one associated with 819 * this process. 820 */ 821 822 for (supptr = &semu_list; (suptr = *supptr) != NULL; 823 supptr = &suptr->un_next) { 824 if (suptr->un_proc == p) 825 break; 826 } 827 828 /* 829 * If there is no undo vector, skip to the end. 830 */ 831 832 if (suptr == NULL) 833 return; 834 835 /* 836 * We now have an undo vector for this process. 837 */ 838 839 SEM_PRINTF(("proc @%p has undo structure with %d entries\n", p, 840 suptr->un_cnt)); 841 842 /* 843 * If there are any active undo elements then process them. 844 */ 845 if (suptr->un_cnt > 0) { 846 int ix; 847 848 for (ix = 0; ix < suptr->un_cnt; ix++) { 849 int semid = suptr->un_ent[ix].un_id; 850 int semnum = suptr->un_ent[ix].un_num; 851 int adjval = suptr->un_ent[ix].un_adjval; 852 struct semid_ds *semaptr; 853 854 semaptr = &sema[semid]; 855 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 856 panic("semexit - semid not allocated"); 857 if (semnum >= semaptr->sem_nsems) 858 panic("semexit - semnum out of range"); 859 860 SEM_PRINTF(("semexit: %p id=%d num=%d(adj=%d) ; sem=%d\n", 861 suptr->un_proc, suptr->un_ent[ix].un_id, 862 suptr->un_ent[ix].un_num, 863 suptr->un_ent[ix].un_adjval, 864 semaptr->_sem_base[semnum].semval)); 865 866 if (adjval < 0 && 867 semaptr->_sem_base[semnum].semval < -adjval) 868 semaptr->_sem_base[semnum].semval = 0; 869 else 870 semaptr->_sem_base[semnum].semval += adjval; 871 872 #ifdef SEM_WAKEUP 873 sem_wakeup((caddr_t)semaptr); 874 #else 875 wakeup((caddr_t)semaptr); 876 #endif 877 SEM_PRINTF(("semexit: back from wakeup\n")); 878 } 879 } 880 881 /* 882 * Deallocate the undo vector. 883 */ 884 SEM_PRINTF(("removing vector\n")); 885 suptr->un_proc = NULL; 886 *supptr = suptr->un_next; 887 } 888