1 /* $NetBSD: sysv_sem.c,v 1.59 2005/12/07 06:14:13 thorpej 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 1.59 2005/12/07 06:14:13 thorpej 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(void) 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 v = uvm_km_alloc(kernel_map, round_page(sz), 0, 94 UVM_KMF_WIRED|UVM_KMF_ZERO); 95 if (v == 0) 96 panic("sysv_sem: cannot allocate memory"); 97 sema = (void *)v; 98 sem = (void *)(sema + seminfo.semmni); 99 semu = (void *)(sem + seminfo.semmns); 100 101 for (i = 0; i < seminfo.semmni; i++) { 102 sema[i]._sem_base = 0; 103 sema[i].sem_perm.mode = 0; 104 } 105 for (i = 0; i < seminfo.semmnu; i++) { 106 struct sem_undo *suptr = SEMU(i); 107 suptr->un_proc = NULL; 108 } 109 semu_list = NULL; 110 exithook_establish(semexit, NULL); 111 } 112 113 /* 114 * Placebo. 115 */ 116 117 int 118 sys_semconfig(struct lwp *l, void *v, register_t *retval) 119 { 120 121 *retval = 0; 122 return 0; 123 } 124 125 /* 126 * Allocate a new sem_undo structure for a process 127 * (returns ptr to structure or NULL if no more room) 128 */ 129 130 struct sem_undo * 131 semu_alloc(struct proc *p) 132 { 133 int i; 134 struct sem_undo *suptr; 135 struct sem_undo **supptr; 136 int attempt; 137 138 /* 139 * Try twice to allocate something. 140 * (we'll purge any empty structures after the first pass so 141 * two passes are always enough) 142 */ 143 144 for (attempt = 0; attempt < 2; attempt++) { 145 /* 146 * Look for a free structure. 147 * Fill it in and return it if we find one. 148 */ 149 150 for (i = 0; i < seminfo.semmnu; i++) { 151 suptr = SEMU(i); 152 if (suptr->un_proc == NULL) { 153 suptr->un_next = semu_list; 154 semu_list = suptr; 155 suptr->un_cnt = 0; 156 suptr->un_proc = p; 157 return (suptr); 158 } 159 } 160 161 /* 162 * We didn't find a free one, if this is the first attempt 163 * then try to free some structures. 164 */ 165 166 if (attempt == 0) { 167 /* All the structures are in use - try to free some */ 168 int did_something = 0; 169 170 supptr = &semu_list; 171 while ((suptr = *supptr) != NULL) { 172 if (suptr->un_cnt == 0) { 173 suptr->un_proc = NULL; 174 *supptr = suptr->un_next; 175 did_something = 1; 176 } else 177 supptr = &suptr->un_next; 178 } 179 180 /* If we didn't free anything then just give-up */ 181 if (!did_something) 182 return (NULL); 183 } else { 184 /* 185 * The second pass failed even though we freed 186 * something after the first pass! 187 * This is IMPOSSIBLE! 188 */ 189 panic("semu_alloc - second attempt failed"); 190 } 191 } 192 return NULL; 193 } 194 195 /* 196 * Adjust a particular entry for a particular proc 197 */ 198 199 int 200 semundo_adjust(struct proc *p, struct sem_undo **supptr, int semid, int semnum, 201 int adjval) 202 { 203 struct sem_undo *suptr; 204 struct undo *sunptr; 205 int i; 206 207 /* 208 * Look for and remember the sem_undo if the caller doesn't 209 * provide it 210 */ 211 212 suptr = *supptr; 213 if (suptr == NULL) { 214 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) 215 if (suptr->un_proc == p) 216 break; 217 218 if (suptr == NULL) { 219 suptr = semu_alloc(p); 220 if (suptr == NULL) 221 return (ENOSPC); 222 } 223 *supptr = suptr; 224 } 225 226 /* 227 * Look for the requested entry and adjust it (delete if 228 * adjval becomes 0). 229 */ 230 sunptr = &suptr->un_ent[0]; 231 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 232 if (sunptr->un_id != semid || sunptr->un_num != semnum) 233 continue; 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 (suptr->un_cnt == SEMUME) 246 return (EINVAL); 247 248 sunptr = &suptr->un_ent[suptr->un_cnt]; 249 suptr->un_cnt++; 250 sunptr->un_adjval = adjval; 251 sunptr->un_id = semid; 252 sunptr->un_num = semnum; 253 return (0); 254 } 255 256 void 257 semundo_clear(int semid, int semnum) 258 { 259 struct sem_undo *suptr; 260 struct undo *sunptr, *sunend; 261 262 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) 263 for (sunptr = &suptr->un_ent[0], 264 sunend = sunptr + suptr->un_cnt; sunptr < sunend;) { 265 if (sunptr->un_id == semid) { 266 if (semnum == -1 || sunptr->un_num == semnum) { 267 suptr->un_cnt--; 268 sunend--; 269 if (sunptr != sunend) 270 *sunptr = *sunend; 271 if (semnum != -1) 272 break; 273 else 274 continue; 275 } 276 } 277 sunptr++; 278 } 279 } 280 281 int 282 sys_____semctl13(struct lwp *l, void *v, register_t *retval) 283 { 284 struct sys_____semctl13_args /* { 285 syscallarg(int) semid; 286 syscallarg(int) semnum; 287 syscallarg(int) cmd; 288 syscallarg(union __semun *) arg; 289 } */ *uap = v; 290 struct proc *p = l->l_proc; 291 struct semid_ds sembuf; 292 int cmd, error; 293 void *pass_arg; 294 union __semun karg; 295 296 cmd = SCARG(uap, cmd); 297 298 switch (cmd) { 299 case IPC_SET: 300 case IPC_STAT: 301 pass_arg = &sembuf; 302 break; 303 304 case GETALL: 305 case SETVAL: 306 case SETALL: 307 pass_arg = &karg; 308 break; 309 default: 310 pass_arg = NULL; 311 break; 312 } 313 314 if (pass_arg) { 315 error = copyin(SCARG(uap, arg), &karg, sizeof(karg)); 316 if (error) 317 return error; 318 if (cmd == IPC_SET) { 319 error = copyin(karg.buf, &sembuf, sizeof(sembuf)); 320 if (error) 321 return (error); 322 } 323 } 324 325 error = semctl1(p, SCARG(uap, semid), SCARG(uap, semnum), cmd, 326 pass_arg, retval); 327 328 if (error == 0 && cmd == IPC_STAT) 329 error = copyout(&sembuf, karg.buf, sizeof(sembuf)); 330 331 return (error); 332 } 333 334 int 335 semctl1(struct proc *p, int semid, int semnum, int cmd, void *v, 336 register_t *retval) 337 { 338 struct ucred *cred = p->p_ucred; 339 union __semun *arg = v; 340 struct semid_ds *sembuf = v, *semaptr; 341 int i, error, ix; 342 343 SEM_PRINTF(("call to semctl(%d, %d, %d, %p)\n", 344 semid, semnum, cmd, v)); 345 346 ix = IPCID_TO_IX(semid); 347 if (ix < 0 || ix >= seminfo.semmni) 348 return (EINVAL); 349 350 semaptr = &sema[ix]; 351 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 352 semaptr->sem_perm._seq != IPCID_TO_SEQ(semid)) 353 return (EINVAL); 354 355 switch (cmd) { 356 case IPC_RMID: 357 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M)) != 0) 358 return (error); 359 semaptr->sem_perm.cuid = cred->cr_uid; 360 semaptr->sem_perm.uid = cred->cr_uid; 361 semtot -= semaptr->sem_nsems; 362 for (i = semaptr->_sem_base - sem; i < semtot; i++) 363 sem[i] = sem[i + semaptr->sem_nsems]; 364 for (i = 0; i < seminfo.semmni; i++) { 365 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 366 sema[i]._sem_base > semaptr->_sem_base) 367 sema[i]._sem_base -= semaptr->sem_nsems; 368 } 369 semaptr->sem_perm.mode = 0; 370 semundo_clear(ix, -1); 371 wakeup(semaptr); 372 break; 373 374 case IPC_SET: 375 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_M))) 376 return (error); 377 semaptr->sem_perm.uid = sembuf->sem_perm.uid; 378 semaptr->sem_perm.gid = sembuf->sem_perm.gid; 379 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 380 (sembuf->sem_perm.mode & 0777); 381 semaptr->sem_ctime = time.tv_sec; 382 break; 383 384 case IPC_STAT: 385 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 386 return (error); 387 memcpy(sembuf, semaptr, sizeof(struct semid_ds)); 388 break; 389 390 case GETNCNT: 391 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 392 return (error); 393 if (semnum < 0 || semnum >= semaptr->sem_nsems) 394 return (EINVAL); 395 *retval = semaptr->_sem_base[semnum].semncnt; 396 break; 397 398 case GETPID: 399 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 400 return (error); 401 if (semnum < 0 || semnum >= semaptr->sem_nsems) 402 return (EINVAL); 403 *retval = semaptr->_sem_base[semnum].sempid; 404 break; 405 406 case GETVAL: 407 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 408 return (error); 409 if (semnum < 0 || semnum >= semaptr->sem_nsems) 410 return (EINVAL); 411 *retval = semaptr->_sem_base[semnum].semval; 412 break; 413 414 case GETALL: 415 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 416 return (error); 417 for (i = 0; i < semaptr->sem_nsems; i++) { 418 error = copyout(&semaptr->_sem_base[i].semval, 419 &arg->array[i], sizeof(arg->array[i])); 420 if (error != 0) 421 break; 422 } 423 break; 424 425 case GETZCNT: 426 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_R))) 427 return (error); 428 if (semnum < 0 || semnum >= semaptr->sem_nsems) 429 return (EINVAL); 430 *retval = semaptr->_sem_base[semnum].semzcnt; 431 break; 432 433 case SETVAL: 434 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) 435 return (error); 436 if (semnum < 0 || semnum >= semaptr->sem_nsems) 437 return (EINVAL); 438 semaptr->_sem_base[semnum].semval = arg->val; 439 semundo_clear(ix, semnum); 440 wakeup(semaptr); 441 break; 442 443 case SETALL: 444 if ((error = ipcperm(cred, &semaptr->sem_perm, IPC_W))) 445 return (error); 446 for (i = 0; i < semaptr->sem_nsems; i++) { 447 error = copyin(&arg->array[i], 448 &semaptr->_sem_base[i].semval, 449 sizeof(arg->array[i])); 450 if (error != 0) 451 break; 452 } 453 semundo_clear(ix, -1); 454 wakeup(semaptr); 455 break; 456 457 default: 458 return (EINVAL); 459 } 460 461 return (error); 462 } 463 464 int 465 sys_semget(struct lwp *l, void *v, register_t *retval) 466 { 467 struct sys_semget_args /* { 468 syscallarg(key_t) key; 469 syscallarg(int) nsems; 470 syscallarg(int) semflg; 471 } */ *uap = v; 472 int semid, eval; 473 int key = SCARG(uap, key); 474 int nsems = SCARG(uap, nsems); 475 int semflg = SCARG(uap, semflg); 476 struct ucred *cred = l->l_proc->p_ucred; 477 478 SEM_PRINTF(("semget(0x%x, %d, 0%o)\n", key, nsems, semflg)); 479 480 if (key != IPC_PRIVATE) { 481 for (semid = 0; semid < seminfo.semmni; semid++) { 482 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 483 sema[semid].sem_perm._key == key) 484 break; 485 } 486 if (semid < seminfo.semmni) { 487 SEM_PRINTF(("found public key\n")); 488 if ((eval = ipcperm(cred, &sema[semid].sem_perm, 489 semflg & 0700))) 490 return (eval); 491 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 492 SEM_PRINTF(("too small\n")); 493 return (EINVAL); 494 } 495 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 496 SEM_PRINTF(("not exclusive\n")); 497 return (EEXIST); 498 } 499 goto found; 500 } 501 } 502 503 SEM_PRINTF(("need to allocate the semid_ds\n")); 504 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 505 if (nsems <= 0 || nsems > seminfo.semmsl) { 506 SEM_PRINTF(("nsems out of range (0<%d<=%d)\n", nsems, 507 seminfo.semmsl)); 508 return (EINVAL); 509 } 510 if (nsems > seminfo.semmns - semtot) { 511 SEM_PRINTF(("not enough semaphores left " 512 "(need %d, got %d)\n", 513 nsems, seminfo.semmns - semtot)); 514 return (ENOSPC); 515 } 516 for (semid = 0; semid < seminfo.semmni; semid++) { 517 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 518 break; 519 } 520 if (semid == seminfo.semmni) { 521 SEM_PRINTF(("no more semid_ds's available\n")); 522 return (ENOSPC); 523 } 524 SEM_PRINTF(("semid %d is available\n", semid)); 525 sema[semid].sem_perm._key = key; 526 sema[semid].sem_perm.cuid = cred->cr_uid; 527 sema[semid].sem_perm.uid = cred->cr_uid; 528 sema[semid].sem_perm.cgid = cred->cr_gid; 529 sema[semid].sem_perm.gid = cred->cr_gid; 530 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 531 sema[semid].sem_perm._seq = 532 (sema[semid].sem_perm._seq + 1) & 0x7fff; 533 sema[semid].sem_nsems = nsems; 534 sema[semid].sem_otime = 0; 535 sema[semid].sem_ctime = time.tv_sec; 536 sema[semid]._sem_base = &sem[semtot]; 537 semtot += nsems; 538 memset(sema[semid]._sem_base, 0, 539 sizeof(sema[semid]._sem_base[0]) * nsems); 540 SEM_PRINTF(("sembase = %p, next = %p\n", sema[semid]._sem_base, 541 &sem[semtot])); 542 } else { 543 SEM_PRINTF(("didn't find it and wasn't asked to create it\n")); 544 return (ENOENT); 545 } 546 547 found: 548 *retval = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 549 return (0); 550 } 551 552 #define SMALL_SOPS 8 553 554 int 555 sys_semop(struct lwp *l, void *v, register_t *retval) 556 { 557 struct sys_semop_args /* { 558 syscallarg(int) semid; 559 syscallarg(struct sembuf *) sops; 560 syscallarg(size_t) nsops; 561 } */ *uap = v; 562 struct proc *p = l->l_proc; 563 int semid = SCARG(uap, semid), seq; 564 size_t nsops = SCARG(uap, nsops); 565 struct sembuf small_sops[SMALL_SOPS]; 566 struct sembuf *sops; 567 struct semid_ds *semaptr; 568 struct sembuf *sopptr = NULL; 569 struct __sem *semptr = NULL; 570 struct sem_undo *suptr = NULL; 571 struct ucred *cred = p->p_ucred; 572 int i, eval; 573 int do_wakeup, do_undos; 574 575 SEM_PRINTF(("call to semop(%d, %p, %zd)\n", semid, SCARG(uap,sops), nsops)); 576 577 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 578 if (semid < 0 || semid >= seminfo.semmni) 579 return (EINVAL); 580 581 semaptr = &sema[semid]; 582 seq = IPCID_TO_SEQ(SCARG(uap, semid)); 583 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 584 semaptr->sem_perm._seq != seq) 585 return (EINVAL); 586 587 if ((eval = ipcperm(cred, &semaptr->sem_perm, IPC_W))) { 588 SEM_PRINTF(("eval = %d from ipaccess\n", eval)); 589 return (eval); 590 } 591 592 if (nsops <= SMALL_SOPS) { 593 sops = small_sops; 594 } else if (nsops <= seminfo.semopm) { 595 sops = malloc(nsops * sizeof(*sops), M_TEMP, M_WAITOK); 596 } else { 597 SEM_PRINTF(("too many sops (max=%d, nsops=%zd)\n", 598 seminfo.semopm, nsops)); 599 return (E2BIG); 600 } 601 602 if ((eval = copyin(SCARG(uap, sops), 603 sops, nsops * sizeof(sops[0]))) != 0) { 604 SEM_PRINTF(("eval = %d from copyin(%p, %p, %zd)\n", eval, 605 SCARG(uap, sops), &sops, nsops * sizeof(sops[0]))); 606 goto out; 607 } 608 609 for (i = 0; i < nsops; i++) 610 if (sops[i].sem_num >= semaptr->sem_nsems) { 611 eval = EFBIG; 612 goto out; 613 } 614 615 /* 616 * Loop trying to satisfy the vector of requests. 617 * If we reach a point where we must wait, any requests already 618 * performed are rolled back and we go to sleep until some other 619 * process wakes us up. At this point, we start all over again. 620 * 621 * This ensures that from the perspective of other tasks, a set 622 * of requests is atomic (never partially satisfied). 623 */ 624 do_undos = 0; 625 626 for (;;) { 627 do_wakeup = 0; 628 629 for (i = 0; i < nsops; i++) { 630 sopptr = &sops[i]; 631 semptr = &semaptr->_sem_base[sopptr->sem_num]; 632 633 SEM_PRINTF(("semop: semaptr=%p, sem_base=%p, " 634 "semptr=%p, sem[%d]=%d : op=%d, flag=%s\n", 635 semaptr, semaptr->_sem_base, semptr, 636 sopptr->sem_num, semptr->semval, sopptr->sem_op, 637 (sopptr->sem_flg & IPC_NOWAIT) ? 638 "nowait" : "wait")); 639 640 if (sopptr->sem_op < 0) { 641 if ((int)(semptr->semval + 642 sopptr->sem_op) < 0) { 643 SEM_PRINTF(("semop: " 644 "can't do it now\n")); 645 break; 646 } else { 647 semptr->semval += sopptr->sem_op; 648 if (semptr->semval == 0 && 649 semptr->semzcnt > 0) 650 do_wakeup = 1; 651 } 652 if (sopptr->sem_flg & SEM_UNDO) 653 do_undos = 1; 654 } else if (sopptr->sem_op == 0) { 655 if (semptr->semval > 0) { 656 SEM_PRINTF(("semop: not zero now\n")); 657 break; 658 } 659 } else { 660 if (semptr->semncnt > 0) 661 do_wakeup = 1; 662 semptr->semval += sopptr->sem_op; 663 if (sopptr->sem_flg & SEM_UNDO) 664 do_undos = 1; 665 } 666 } 667 668 /* 669 * Did we get through the entire vector? 670 */ 671 if (i >= nsops) 672 goto done; 673 674 /* 675 * No ... rollback anything that we've already done 676 */ 677 SEM_PRINTF(("semop: rollback 0 through %d\n", i - 1)); 678 while (i-- > 0) 679 semaptr->_sem_base[sops[i].sem_num].semval -= 680 sops[i].sem_op; 681 682 /* 683 * If the request that we couldn't satisfy has the 684 * NOWAIT flag set then return with EAGAIN. 685 */ 686 if (sopptr->sem_flg & IPC_NOWAIT) { 687 eval = EAGAIN; 688 goto out; 689 } 690 691 if (sopptr->sem_op == 0) 692 semptr->semzcnt++; 693 else 694 semptr->semncnt++; 695 696 SEM_PRINTF(("semop: good night!\n")); 697 eval = tsleep((caddr_t)semaptr, (PZERO - 4) | PCATCH, 698 "semwait", 0); 699 SEM_PRINTF(("semop: good morning (eval=%d)!\n", eval)); 700 701 /* 702 * Make sure that the semaphore still exists 703 */ 704 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 705 semaptr->sem_perm._seq != seq) { 706 eval = EIDRM; 707 goto out; 708 } 709 710 /* 711 * The semaphore is still alive. Readjust the count of 712 * waiting processes. 713 */ 714 semptr = &semaptr->_sem_base[sopptr->sem_num]; 715 if (sopptr->sem_op == 0) 716 semptr->semzcnt--; 717 else 718 semptr->semncnt--; 719 /* 720 * Is it really morning, or was our sleep interrupted? 721 * (Delayed check of tsleep() return code because we 722 * need to decrement sem[nz]cnt either way.) 723 */ 724 if (eval != 0) { 725 eval = EINTR; 726 goto out; 727 } 728 SEM_PRINTF(("semop: good morning!\n")); 729 } 730 731 done: 732 /* 733 * Process any SEM_UNDO requests. 734 */ 735 if (do_undos) { 736 for (i = 0; i < nsops; i++) { 737 /* 738 * We only need to deal with SEM_UNDO's for non-zero 739 * op's. 740 */ 741 int adjval; 742 743 if ((sops[i].sem_flg & SEM_UNDO) == 0) 744 continue; 745 adjval = sops[i].sem_op; 746 if (adjval == 0) 747 continue; 748 eval = semundo_adjust(p, &suptr, semid, 749 sops[i].sem_num, -adjval); 750 if (eval == 0) 751 continue; 752 753 /* 754 * Oh-Oh! We ran out of either sem_undo's or undo's. 755 * Rollback the adjustments to this point and then 756 * rollback the semaphore ups and down so we can return 757 * with an error with all structures restored. We 758 * rollback the undo's in the exact reverse order that 759 * we applied them. This guarantees that we won't run 760 * out of space as we roll things back out. 761 */ 762 while (i-- > 0) { 763 if ((sops[i].sem_flg & SEM_UNDO) == 0) 764 continue; 765 adjval = sops[i].sem_op; 766 if (adjval == 0) 767 continue; 768 if (semundo_adjust(p, &suptr, semid, 769 sops[i].sem_num, adjval) != 0) 770 panic("semop - can't undo undos"); 771 } 772 773 for (i = 0; i < nsops; i++) 774 semaptr->_sem_base[sops[i].sem_num].semval -= 775 sops[i].sem_op; 776 777 SEM_PRINTF(("eval = %d from semundo_adjust\n", eval)); 778 goto out; 779 } /* loop through the sops */ 780 } /* if (do_undos) */ 781 782 /* We're definitely done - set the sempid's */ 783 for (i = 0; i < nsops; i++) { 784 sopptr = &sops[i]; 785 semptr = &semaptr->_sem_base[sopptr->sem_num]; 786 semptr->sempid = p->p_pid; 787 } 788 789 /* Update sem_otime */ 790 semaptr->sem_otime = time.tv_sec; 791 792 /* Do a wakeup if any semaphore was up'd. */ 793 if (do_wakeup) { 794 SEM_PRINTF(("semop: doing wakeup\n")); 795 #ifdef SEM_WAKEUP 796 sem_wakeup((caddr_t)semaptr); 797 #else 798 wakeup((caddr_t)semaptr); 799 #endif 800 SEM_PRINTF(("semop: back from wakeup\n")); 801 } 802 SEM_PRINTF(("semop: done\n")); 803 *retval = 0; 804 805 out: 806 if (sops != small_sops) { 807 free(sops, M_TEMP); 808 } 809 return eval; 810 } 811 812 /* 813 * Go through the undo structures for this process and apply the 814 * adjustments to semaphores. 815 */ 816 /*ARGSUSED*/ 817 void 818 semexit(struct proc *p, void *v) 819 { 820 struct sem_undo *suptr; 821 struct sem_undo **supptr; 822 823 /* 824 * Go through the chain of undo vectors looking for one 825 * associated with this process. 826 */ 827 828 for (supptr = &semu_list; (suptr = *supptr) != NULL; 829 supptr = &suptr->un_next) { 830 if (suptr->un_proc == p) 831 break; 832 } 833 834 /* 835 * If there is no undo vector, skip to the end. 836 */ 837 838 if (suptr == NULL) 839 return; 840 841 /* 842 * We now have an undo vector for this process. 843 */ 844 845 SEM_PRINTF(("proc @%p has undo structure with %d entries\n", p, 846 suptr->un_cnt)); 847 848 /* 849 * If there are any active undo elements then process them. 850 */ 851 if (suptr->un_cnt > 0) { 852 int ix; 853 854 for (ix = 0; ix < suptr->un_cnt; ix++) { 855 int semid = suptr->un_ent[ix].un_id; 856 int semnum = suptr->un_ent[ix].un_num; 857 int adjval = suptr->un_ent[ix].un_adjval; 858 struct semid_ds *semaptr; 859 860 semaptr = &sema[semid]; 861 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 862 panic("semexit - semid not allocated"); 863 if (semnum >= semaptr->sem_nsems) 864 panic("semexit - semnum out of range"); 865 866 SEM_PRINTF(("semexit: %p id=%d num=%d(adj=%d) ; " 867 "sem=%d\n", 868 suptr->un_proc, suptr->un_ent[ix].un_id, 869 suptr->un_ent[ix].un_num, 870 suptr->un_ent[ix].un_adjval, 871 semaptr->_sem_base[semnum].semval)); 872 873 if (adjval < 0 && 874 semaptr->_sem_base[semnum].semval < -adjval) 875 semaptr->_sem_base[semnum].semval = 0; 876 else 877 semaptr->_sem_base[semnum].semval += adjval; 878 879 #ifdef SEM_WAKEUP 880 sem_wakeup((caddr_t)semaptr); 881 #else 882 wakeup((caddr_t)semaptr); 883 #endif 884 SEM_PRINTF(("semexit: back from wakeup\n")); 885 } 886 } 887 888 /* 889 * Deallocate the undo vector. 890 */ 891 SEM_PRINTF(("removing vector\n")); 892 suptr->un_proc = NULL; 893 *supptr = suptr->un_next; 894 } 895