1 /* $FreeBSD$ */ 2 3 /* 4 * Implementation of SVID semaphores 5 * 6 * Author: Daniel Boulet 7 * 8 * This software is provided ``AS IS'' without any warranties of any kind. 9 */ 10 11 #include "opt_sysvipc.h" 12 13 #include <sys/param.h> 14 #include <sys/systm.h> 15 #include <sys/sysproto.h> 16 #include <sys/kernel.h> 17 #include <sys/proc.h> 18 #include <sys/sem.h> 19 #include <sys/sysent.h> 20 #include <sys/sysctl.h> 21 #include <sys/malloc.h> 22 23 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores"); 24 25 static void seminit __P((void *)); 26 27 #ifndef _SYS_SYSPROTO_H_ 28 struct __semctl_args; 29 int __semctl __P((struct proc *p, struct __semctl_args *uap)); 30 struct semget_args; 31 int semget __P((struct proc *p, struct semget_args *uap)); 32 struct semop_args; 33 int semop __P((struct proc *p, struct semop_args *uap)); 34 #endif 35 36 static struct sem_undo *semu_alloc __P((struct proc *p)); 37 static int semundo_adjust __P((struct proc *p, struct sem_undo **supptr, 38 int semid, int semnum, int adjval)); 39 static void semundo_clear __P((int semid, int semnum)); 40 41 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 42 static sy_call_t *semcalls[] = { 43 (sy_call_t *)__semctl, (sy_call_t *)semget, 44 (sy_call_t *)semop 45 }; 46 47 static int semtot = 0; 48 static struct semid_ds *sema; /* semaphore id pool */ 49 static struct sem *sem; /* semaphore pool */ 50 static struct sem_undo *semu_list; /* list of active undo structures */ 51 static int *semu; /* undo structure pool */ 52 53 struct sem { 54 u_short semval; /* semaphore value */ 55 pid_t sempid; /* pid of last operation */ 56 u_short semncnt; /* # awaiting semval > cval */ 57 u_short semzcnt; /* # awaiting semval = 0 */ 58 }; 59 60 /* 61 * Undo structure (one per process) 62 */ 63 struct sem_undo { 64 struct sem_undo *un_next; /* ptr to next active undo structure */ 65 struct proc *un_proc; /* owner of this structure */ 66 short un_cnt; /* # of active entries */ 67 struct undo { 68 short un_adjval; /* adjust on exit values */ 69 short un_num; /* semaphore # */ 70 int un_id; /* semid */ 71 } un_ent[1]; /* undo entries */ 72 }; 73 74 /* 75 * Configuration parameters 76 */ 77 #ifndef SEMMNI 78 #define SEMMNI 10 /* # of semaphore identifiers */ 79 #endif 80 #ifndef SEMMNS 81 #define SEMMNS 60 /* # of semaphores in system */ 82 #endif 83 #ifndef SEMUME 84 #define SEMUME 10 /* max # of undo entries per process */ 85 #endif 86 #ifndef SEMMNU 87 #define SEMMNU 30 /* # of undo structures in system */ 88 #endif 89 90 /* shouldn't need tuning */ 91 #ifndef SEMMAP 92 #define SEMMAP 30 /* # of entries in semaphore map */ 93 #endif 94 #ifndef SEMMSL 95 #define SEMMSL SEMMNS /* max # of semaphores per id */ 96 #endif 97 #ifndef SEMOPM 98 #define SEMOPM 100 /* max # of operations per semop call */ 99 #endif 100 101 #define SEMVMX 32767 /* semaphore maximum value */ 102 #define SEMAEM 16384 /* adjust on exit max value */ 103 104 /* 105 * Due to the way semaphore memory is allocated, we have to ensure that 106 * SEMUSZ is properly aligned. 107 */ 108 109 #ifndef offsetof 110 #define offsetof(type, member) ((size_t)(&((type *)0)->member)) 111 #endif 112 113 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1)) 114 115 /* actual size of an undo structure */ 116 #define SEMUSZ SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME])) 117 118 /* 119 * Macro to find a particular sem_undo vector 120 */ 121 #define SEMU(ix) ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz)) 122 123 /* 124 * semaphore info struct 125 */ 126 struct seminfo seminfo = { 127 SEMMAP, /* # of entries in semaphore map */ 128 SEMMNI, /* # of semaphore identifiers */ 129 SEMMNS, /* # of semaphores in system */ 130 SEMMNU, /* # of undo structures in system */ 131 SEMMSL, /* max # of semaphores per id */ 132 SEMOPM, /* max # of operations per semop call */ 133 SEMUME, /* max # of undo entries per process */ 134 SEMUSZ, /* size in bytes of undo structure */ 135 SEMVMX, /* semaphore maximum value */ 136 SEMAEM /* adjust on exit max value */ 137 }; 138 139 SYSCTL_DECL(_kern_ipc); 140 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, ""); 141 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0, ""); 142 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0, ""); 143 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0, ""); 144 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, ""); 145 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0, ""); 146 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0, ""); 147 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0, ""); 148 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, ""); 149 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, ""); 150 151 #if 0 152 RO seminfo.semmap /* SEMMAP unused */ 153 RO seminfo.semmni 154 RO seminfo.semmns 155 RO seminfo.semmnu /* undo entries per system */ 156 RW seminfo.semmsl 157 RO seminfo.semopm /* SEMOPM unused */ 158 RO seminfo.semume 159 RO seminfo.semusz /* param - derived from SEMUME for per-proc sizeof */ 160 RO seminfo.semvmx /* SEMVMX unused - user param */ 161 RO seminfo.semaem /* SEMAEM unused - user param */ 162 #endif 163 164 static void 165 seminit(dummy) 166 void *dummy; 167 { 168 register int i; 169 170 sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK); 171 if (sem == NULL) 172 panic("sem is NULL"); 173 sema = malloc(sizeof(struct semid_ds) * seminfo.semmni, M_SEM, M_WAITOK); 174 if (sema == NULL) 175 panic("sema is NULL"); 176 semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK); 177 if (semu == NULL) 178 panic("semu is NULL"); 179 180 for (i = 0; i < seminfo.semmni; i++) { 181 sema[i].sem_base = 0; 182 sema[i].sem_perm.mode = 0; 183 } 184 for (i = 0; i < seminfo.semmnu; i++) { 185 register struct sem_undo *suptr = SEMU(i); 186 suptr->un_proc = NULL; 187 } 188 semu_list = NULL; 189 } 190 SYSINIT(sysv_sem, SI_SUB_SYSV_SEM, SI_ORDER_FIRST, seminit, NULL) 191 192 /* 193 * Entry point for all SEM calls 194 */ 195 int 196 semsys(p, uap) 197 struct proc *p; 198 /* XXX actually varargs. */ 199 struct semsys_args /* { 200 u_int which; 201 int a2; 202 int a3; 203 int a4; 204 int a5; 205 } */ *uap; 206 { 207 208 if (uap->which >= sizeof(semcalls)/sizeof(semcalls[0])) 209 return (EINVAL); 210 return ((*semcalls[uap->which])(p, &uap->a2)); 211 } 212 213 /* 214 * Allocate a new sem_undo structure for a process 215 * (returns ptr to structure or NULL if no more room) 216 */ 217 218 static struct sem_undo * 219 semu_alloc(p) 220 struct proc *p; 221 { 222 register int i; 223 register struct sem_undo *suptr; 224 register struct sem_undo **supptr; 225 int attempt; 226 227 /* 228 * Try twice to allocate something. 229 * (we'll purge any empty structures after the first pass so 230 * two passes are always enough) 231 */ 232 233 for (attempt = 0; attempt < 2; attempt++) { 234 /* 235 * Look for a free structure. 236 * Fill it in and return it if we find one. 237 */ 238 239 for (i = 0; i < seminfo.semmnu; i++) { 240 suptr = SEMU(i); 241 if (suptr->un_proc == NULL) { 242 suptr->un_next = semu_list; 243 semu_list = suptr; 244 suptr->un_cnt = 0; 245 suptr->un_proc = p; 246 return(suptr); 247 } 248 } 249 250 /* 251 * We didn't find a free one, if this is the first attempt 252 * then try to free some structures. 253 */ 254 255 if (attempt == 0) { 256 /* All the structures are in use - try to free some */ 257 int did_something = 0; 258 259 supptr = &semu_list; 260 while ((suptr = *supptr) != NULL) { 261 if (suptr->un_cnt == 0) { 262 suptr->un_proc = NULL; 263 *supptr = suptr->un_next; 264 did_something = 1; 265 } else 266 supptr = &(suptr->un_next); 267 } 268 269 /* If we didn't free anything then just give-up */ 270 if (!did_something) 271 return(NULL); 272 } else { 273 /* 274 * The second pass failed even though we freed 275 * something after the first pass! 276 * This is IMPOSSIBLE! 277 */ 278 panic("semu_alloc - second attempt failed"); 279 } 280 } 281 return (NULL); 282 } 283 284 /* 285 * Adjust a particular entry for a particular proc 286 */ 287 288 static int 289 semundo_adjust(p, supptr, semid, semnum, adjval) 290 register struct proc *p; 291 struct sem_undo **supptr; 292 int semid, semnum; 293 int adjval; 294 { 295 register struct sem_undo *suptr; 296 register struct undo *sunptr; 297 int i; 298 299 /* Look for and remember the sem_undo if the caller doesn't provide 300 it */ 301 302 suptr = *supptr; 303 if (suptr == NULL) { 304 for (suptr = semu_list; suptr != NULL; 305 suptr = suptr->un_next) { 306 if (suptr->un_proc == p) { 307 *supptr = suptr; 308 break; 309 } 310 } 311 if (suptr == NULL) { 312 if (adjval == 0) 313 return(0); 314 suptr = semu_alloc(p); 315 if (suptr == NULL) 316 return(ENOSPC); 317 *supptr = suptr; 318 } 319 } 320 321 /* 322 * Look for the requested entry and adjust it (delete if adjval becomes 323 * 0). 324 */ 325 sunptr = &suptr->un_ent[0]; 326 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 327 if (sunptr->un_id != semid || sunptr->un_num != semnum) 328 continue; 329 if (adjval == 0) 330 sunptr->un_adjval = 0; 331 else 332 sunptr->un_adjval += adjval; 333 if (sunptr->un_adjval == 0) { 334 suptr->un_cnt--; 335 if (i < suptr->un_cnt) 336 suptr->un_ent[i] = 337 suptr->un_ent[suptr->un_cnt]; 338 } 339 return(0); 340 } 341 342 /* Didn't find the right entry - create it */ 343 if (adjval == 0) 344 return(0); 345 if (suptr->un_cnt != seminfo.semume) { 346 sunptr = &suptr->un_ent[suptr->un_cnt]; 347 suptr->un_cnt++; 348 sunptr->un_adjval = adjval; 349 sunptr->un_id = semid; sunptr->un_num = semnum; 350 } else 351 return(EINVAL); 352 return(0); 353 } 354 355 static void 356 semundo_clear(semid, semnum) 357 int semid, semnum; 358 { 359 register struct sem_undo *suptr; 360 361 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { 362 register struct undo *sunptr = &suptr->un_ent[0]; 363 register int i = 0; 364 365 while (i < suptr->un_cnt) { 366 if (sunptr->un_id == semid) { 367 if (semnum == -1 || sunptr->un_num == semnum) { 368 suptr->un_cnt--; 369 if (i < suptr->un_cnt) { 370 suptr->un_ent[i] = 371 suptr->un_ent[suptr->un_cnt]; 372 continue; 373 } 374 } 375 if (semnum != -1) 376 break; 377 } 378 i++, sunptr++; 379 } 380 } 381 } 382 383 /* 384 * Note that the user-mode half of this passes a union, not a pointer 385 */ 386 #ifndef _SYS_SYSPROTO_H_ 387 struct __semctl_args { 388 int semid; 389 int semnum; 390 int cmd; 391 union semun *arg; 392 }; 393 #endif 394 395 int 396 __semctl(p, uap) 397 struct proc *p; 398 register struct __semctl_args *uap; 399 { 400 int semid = uap->semid; 401 int semnum = uap->semnum; 402 int cmd = uap->cmd; 403 union semun *arg = uap->arg; 404 union semun real_arg; 405 struct ucred *cred = p->p_ucred; 406 int i, rval, eval; 407 struct semid_ds sbuf; 408 register struct semid_ds *semaptr; 409 410 #ifdef SEM_DEBUG 411 printf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg); 412 #endif 413 414 semid = IPCID_TO_IX(semid); 415 if (semid < 0 || semid >= seminfo.semmsl) 416 return(EINVAL); 417 418 semaptr = &sema[semid]; 419 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 420 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 421 return(EINVAL); 422 423 eval = 0; 424 rval = 0; 425 426 switch (cmd) { 427 case IPC_RMID: 428 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M))) 429 return(eval); 430 semaptr->sem_perm.cuid = cred->cr_uid; 431 semaptr->sem_perm.uid = cred->cr_uid; 432 semtot -= semaptr->sem_nsems; 433 for (i = semaptr->sem_base - sem; i < semtot; i++) 434 sem[i] = sem[i + semaptr->sem_nsems]; 435 for (i = 0; i < seminfo.semmni; i++) { 436 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 437 sema[i].sem_base > semaptr->sem_base) 438 sema[i].sem_base -= semaptr->sem_nsems; 439 } 440 semaptr->sem_perm.mode = 0; 441 semundo_clear(semid, -1); 442 wakeup((caddr_t)semaptr); 443 break; 444 445 case IPC_SET: 446 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M))) 447 return(eval); 448 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 449 return(eval); 450 if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf, 451 sizeof(sbuf))) != 0) 452 return(eval); 453 semaptr->sem_perm.uid = sbuf.sem_perm.uid; 454 semaptr->sem_perm.gid = sbuf.sem_perm.gid; 455 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 456 (sbuf.sem_perm.mode & 0777); 457 semaptr->sem_ctime = time_second; 458 break; 459 460 case IPC_STAT: 461 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 462 return(eval); 463 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 464 return(eval); 465 eval = copyout((caddr_t)semaptr, real_arg.buf, 466 sizeof(struct semid_ds)); 467 break; 468 469 case GETNCNT: 470 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 471 return(eval); 472 if (semnum < 0 || semnum >= semaptr->sem_nsems) 473 return(EINVAL); 474 rval = semaptr->sem_base[semnum].semncnt; 475 break; 476 477 case GETPID: 478 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 479 return(eval); 480 if (semnum < 0 || semnum >= semaptr->sem_nsems) 481 return(EINVAL); 482 rval = semaptr->sem_base[semnum].sempid; 483 break; 484 485 case GETVAL: 486 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 487 return(eval); 488 if (semnum < 0 || semnum >= semaptr->sem_nsems) 489 return(EINVAL); 490 rval = semaptr->sem_base[semnum].semval; 491 break; 492 493 case GETALL: 494 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 495 return(eval); 496 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 497 return(eval); 498 for (i = 0; i < semaptr->sem_nsems; i++) { 499 eval = copyout((caddr_t)&semaptr->sem_base[i].semval, 500 &real_arg.array[i], sizeof(real_arg.array[0])); 501 if (eval != 0) 502 break; 503 } 504 break; 505 506 case GETZCNT: 507 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 508 return(eval); 509 if (semnum < 0 || semnum >= semaptr->sem_nsems) 510 return(EINVAL); 511 rval = semaptr->sem_base[semnum].semzcnt; 512 break; 513 514 case SETVAL: 515 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) 516 return(eval); 517 if (semnum < 0 || semnum >= semaptr->sem_nsems) 518 return(EINVAL); 519 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 520 return(eval); 521 semaptr->sem_base[semnum].semval = real_arg.val; 522 semundo_clear(semid, semnum); 523 wakeup((caddr_t)semaptr); 524 break; 525 526 case SETALL: 527 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) 528 return(eval); 529 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 530 return(eval); 531 for (i = 0; i < semaptr->sem_nsems; i++) { 532 eval = copyin(&real_arg.array[i], 533 (caddr_t)&semaptr->sem_base[i].semval, 534 sizeof(real_arg.array[0])); 535 if (eval != 0) 536 break; 537 } 538 semundo_clear(semid, -1); 539 wakeup((caddr_t)semaptr); 540 break; 541 542 default: 543 return(EINVAL); 544 } 545 546 if (eval == 0) 547 p->p_retval[0] = rval; 548 return(eval); 549 } 550 551 #ifndef _SYS_SYSPROTO_H_ 552 struct semget_args { 553 key_t key; 554 int nsems; 555 int semflg; 556 }; 557 #endif 558 559 int 560 semget(p, uap) 561 struct proc *p; 562 register struct semget_args *uap; 563 { 564 int semid, eval; 565 int key = uap->key; 566 int nsems = uap->nsems; 567 int semflg = uap->semflg; 568 struct ucred *cred = p->p_ucred; 569 570 #ifdef SEM_DEBUG 571 printf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg); 572 #endif 573 574 if (key != IPC_PRIVATE) { 575 for (semid = 0; semid < seminfo.semmni; semid++) { 576 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 577 sema[semid].sem_perm.key == key) 578 break; 579 } 580 if (semid < seminfo.semmni) { 581 #ifdef SEM_DEBUG 582 printf("found public key\n"); 583 #endif 584 if ((eval = ipcperm(p, &sema[semid].sem_perm, 585 semflg & 0700))) 586 return(eval); 587 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 588 #ifdef SEM_DEBUG 589 printf("too small\n"); 590 #endif 591 return(EINVAL); 592 } 593 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 594 #ifdef SEM_DEBUG 595 printf("not exclusive\n"); 596 #endif 597 return(EEXIST); 598 } 599 goto found; 600 } 601 } 602 603 #ifdef SEM_DEBUG 604 printf("need to allocate the semid_ds\n"); 605 #endif 606 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 607 if (nsems <= 0 || nsems > seminfo.semmsl) { 608 #ifdef SEM_DEBUG 609 printf("nsems out of range (0<%d<=%d)\n", nsems, 610 seminfo.semmsl); 611 #endif 612 return(EINVAL); 613 } 614 if (nsems > seminfo.semmns - semtot) { 615 #ifdef SEM_DEBUG 616 printf("not enough semaphores left (need %d, got %d)\n", 617 nsems, seminfo.semmns - semtot); 618 #endif 619 return(ENOSPC); 620 } 621 for (semid = 0; semid < seminfo.semmni; semid++) { 622 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 623 break; 624 } 625 if (semid == seminfo.semmni) { 626 #ifdef SEM_DEBUG 627 printf("no more semid_ds's available\n"); 628 #endif 629 return(ENOSPC); 630 } 631 #ifdef SEM_DEBUG 632 printf("semid %d is available\n", semid); 633 #endif 634 sema[semid].sem_perm.key = key; 635 sema[semid].sem_perm.cuid = cred->cr_uid; 636 sema[semid].sem_perm.uid = cred->cr_uid; 637 sema[semid].sem_perm.cgid = cred->cr_gid; 638 sema[semid].sem_perm.gid = cred->cr_gid; 639 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 640 sema[semid].sem_perm.seq = 641 (sema[semid].sem_perm.seq + 1) & 0x7fff; 642 sema[semid].sem_nsems = nsems; 643 sema[semid].sem_otime = 0; 644 sema[semid].sem_ctime = time_second; 645 sema[semid].sem_base = &sem[semtot]; 646 semtot += nsems; 647 bzero(sema[semid].sem_base, 648 sizeof(sema[semid].sem_base[0])*nsems); 649 #ifdef SEM_DEBUG 650 printf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base, 651 &sem[semtot]); 652 #endif 653 } else { 654 #ifdef SEM_DEBUG 655 printf("didn't find it and wasn't asked to create it\n"); 656 #endif 657 return(ENOENT); 658 } 659 660 found: 661 p->p_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 662 return(0); 663 } 664 665 #ifndef _SYS_SYSPROTO_H_ 666 struct semop_args { 667 int semid; 668 struct sembuf *sops; 669 int nsops; 670 }; 671 #endif 672 673 int 674 semop(p, uap) 675 struct proc *p; 676 register struct semop_args *uap; 677 { 678 int semid = uap->semid; 679 int nsops = uap->nsops; 680 struct sembuf sops[MAX_SOPS]; 681 register struct semid_ds *semaptr; 682 register struct sembuf *sopptr; 683 register struct sem *semptr; 684 struct sem_undo *suptr = NULL; 685 int i, j, eval; 686 int do_wakeup, do_undos; 687 688 #ifdef SEM_DEBUG 689 printf("call to semop(%d, 0x%x, %d)\n", semid, sops, nsops); 690 #endif 691 692 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 693 694 if (semid < 0 || semid >= seminfo.semmsl) 695 return(EINVAL); 696 697 semaptr = &sema[semid]; 698 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 699 return(EINVAL); 700 if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 701 return(EINVAL); 702 703 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) { 704 #ifdef SEM_DEBUG 705 printf("eval = %d from ipaccess\n", eval); 706 #endif 707 return(eval); 708 } 709 710 if (nsops > MAX_SOPS) { 711 #ifdef SEM_DEBUG 712 printf("too many sops (max=%d, nsops=%d)\n", MAX_SOPS, nsops); 713 #endif 714 return(E2BIG); 715 } 716 717 if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) { 718 #ifdef SEM_DEBUG 719 printf("eval = %d from copyin(%08x, %08x, %d)\n", eval, 720 uap->sops, &sops, nsops * sizeof(sops[0])); 721 #endif 722 return(eval); 723 } 724 725 /* 726 * Loop trying to satisfy the vector of requests. 727 * If we reach a point where we must wait, any requests already 728 * performed are rolled back and we go to sleep until some other 729 * process wakes us up. At this point, we start all over again. 730 * 731 * This ensures that from the perspective of other tasks, a set 732 * of requests is atomic (never partially satisfied). 733 */ 734 do_undos = 0; 735 736 for (;;) { 737 do_wakeup = 0; 738 739 for (i = 0; i < nsops; i++) { 740 sopptr = &sops[i]; 741 742 if (sopptr->sem_num >= semaptr->sem_nsems) 743 return(EFBIG); 744 745 semptr = &semaptr->sem_base[sopptr->sem_num]; 746 747 #ifdef SEM_DEBUG 748 printf("semop: semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n", 749 semaptr, semaptr->sem_base, semptr, 750 sopptr->sem_num, semptr->semval, sopptr->sem_op, 751 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait"); 752 #endif 753 754 if (sopptr->sem_op < 0) { 755 if (semptr->semval + sopptr->sem_op < 0) { 756 #ifdef SEM_DEBUG 757 printf("semop: can't do it now\n"); 758 #endif 759 break; 760 } else { 761 semptr->semval += sopptr->sem_op; 762 if (semptr->semval == 0 && 763 semptr->semzcnt > 0) 764 do_wakeup = 1; 765 } 766 if (sopptr->sem_flg & SEM_UNDO) 767 do_undos = 1; 768 } else if (sopptr->sem_op == 0) { 769 if (semptr->semval > 0) { 770 #ifdef SEM_DEBUG 771 printf("semop: not zero now\n"); 772 #endif 773 break; 774 } 775 } else { 776 if (semptr->semncnt > 0) 777 do_wakeup = 1; 778 semptr->semval += sopptr->sem_op; 779 if (sopptr->sem_flg & SEM_UNDO) 780 do_undos = 1; 781 } 782 } 783 784 /* 785 * Did we get through the entire vector? 786 */ 787 if (i >= nsops) 788 goto done; 789 790 /* 791 * No ... rollback anything that we've already done 792 */ 793 #ifdef SEM_DEBUG 794 printf("semop: rollback 0 through %d\n", i-1); 795 #endif 796 for (j = 0; j < i; j++) 797 semaptr->sem_base[sops[j].sem_num].semval -= 798 sops[j].sem_op; 799 800 /* 801 * If the request that we couldn't satisfy has the 802 * NOWAIT flag set then return with EAGAIN. 803 */ 804 if (sopptr->sem_flg & IPC_NOWAIT) 805 return(EAGAIN); 806 807 if (sopptr->sem_op == 0) 808 semptr->semzcnt++; 809 else 810 semptr->semncnt++; 811 812 #ifdef SEM_DEBUG 813 printf("semop: good night!\n"); 814 #endif 815 eval = tsleep((caddr_t)semaptr, (PZERO - 4) | PCATCH, 816 "semwait", 0); 817 #ifdef SEM_DEBUG 818 printf("semop: good morning (eval=%d)!\n", eval); 819 #endif 820 821 suptr = NULL; /* sem_undo may have been reallocated */ 822 823 if (eval != 0) 824 return(EINTR); 825 #ifdef SEM_DEBUG 826 printf("semop: good morning!\n"); 827 #endif 828 829 /* 830 * Make sure that the semaphore still exists 831 */ 832 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 833 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 834 return(EIDRM); 835 836 /* 837 * The semaphore is still alive. Readjust the count of 838 * waiting processes. 839 */ 840 if (sopptr->sem_op == 0) 841 semptr->semzcnt--; 842 else 843 semptr->semncnt--; 844 } 845 846 done: 847 /* 848 * Process any SEM_UNDO requests. 849 */ 850 if (do_undos) { 851 for (i = 0; i < nsops; i++) { 852 /* 853 * We only need to deal with SEM_UNDO's for non-zero 854 * op's. 855 */ 856 int adjval; 857 858 if ((sops[i].sem_flg & SEM_UNDO) == 0) 859 continue; 860 adjval = sops[i].sem_op; 861 if (adjval == 0) 862 continue; 863 eval = semundo_adjust(p, &suptr, semid, 864 sops[i].sem_num, -adjval); 865 if (eval == 0) 866 continue; 867 868 /* 869 * Oh-Oh! We ran out of either sem_undo's or undo's. 870 * Rollback the adjustments to this point and then 871 * rollback the semaphore ups and down so we can return 872 * with an error with all structures restored. We 873 * rollback the undo's in the exact reverse order that 874 * we applied them. This guarantees that we won't run 875 * out of space as we roll things back out. 876 */ 877 for (j = i - 1; j >= 0; j--) { 878 if ((sops[j].sem_flg & SEM_UNDO) == 0) 879 continue; 880 adjval = sops[j].sem_op; 881 if (adjval == 0) 882 continue; 883 if (semundo_adjust(p, &suptr, semid, 884 sops[j].sem_num, adjval) != 0) 885 panic("semop - can't undo undos"); 886 } 887 888 for (j = 0; j < nsops; j++) 889 semaptr->sem_base[sops[j].sem_num].semval -= 890 sops[j].sem_op; 891 892 #ifdef SEM_DEBUG 893 printf("eval = %d from semundo_adjust\n", eval); 894 #endif 895 return(eval); 896 } /* loop through the sops */ 897 } /* if (do_undos) */ 898 899 /* We're definitely done - set the sempid's */ 900 for (i = 0; i < nsops; i++) { 901 sopptr = &sops[i]; 902 semptr = &semaptr->sem_base[sopptr->sem_num]; 903 semptr->sempid = p->p_pid; 904 } 905 906 /* Do a wakeup if any semaphore was up'd. */ 907 if (do_wakeup) { 908 #ifdef SEM_DEBUG 909 printf("semop: doing wakeup\n"); 910 #endif 911 wakeup((caddr_t)semaptr); 912 #ifdef SEM_DEBUG 913 printf("semop: back from wakeup\n"); 914 #endif 915 } 916 #ifdef SEM_DEBUG 917 printf("semop: done\n"); 918 #endif 919 p->p_retval[0] = 0; 920 return(0); 921 } 922 923 /* 924 * Go through the undo structures for this process and apply the adjustments to 925 * semaphores. 926 */ 927 void 928 semexit(p) 929 struct proc *p; 930 { 931 register struct sem_undo *suptr; 932 register struct sem_undo **supptr; 933 int did_something; 934 935 did_something = 0; 936 937 /* 938 * Go through the chain of undo vectors looking for one 939 * associated with this process. 940 */ 941 942 for (supptr = &semu_list; (suptr = *supptr) != NULL; 943 supptr = &suptr->un_next) { 944 if (suptr->un_proc == p) 945 break; 946 } 947 948 if (suptr == NULL) 949 return; 950 951 #ifdef SEM_DEBUG 952 printf("proc @%08x has undo structure with %d entries\n", p, 953 suptr->un_cnt); 954 #endif 955 956 /* 957 * If there are any active undo elements then process them. 958 */ 959 if (suptr->un_cnt > 0) { 960 int ix; 961 962 for (ix = 0; ix < suptr->un_cnt; ix++) { 963 int semid = suptr->un_ent[ix].un_id; 964 int semnum = suptr->un_ent[ix].un_num; 965 int adjval = suptr->un_ent[ix].un_adjval; 966 struct semid_ds *semaptr; 967 968 semaptr = &sema[semid]; 969 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 970 panic("semexit - semid not allocated"); 971 if (semnum >= semaptr->sem_nsems) 972 panic("semexit - semnum out of range"); 973 974 #ifdef SEM_DEBUG 975 printf("semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n", 976 suptr->un_proc, suptr->un_ent[ix].un_id, 977 suptr->un_ent[ix].un_num, 978 suptr->un_ent[ix].un_adjval, 979 semaptr->sem_base[semnum].semval); 980 #endif 981 982 if (adjval < 0) { 983 if (semaptr->sem_base[semnum].semval < -adjval) 984 semaptr->sem_base[semnum].semval = 0; 985 else 986 semaptr->sem_base[semnum].semval += 987 adjval; 988 } else 989 semaptr->sem_base[semnum].semval += adjval; 990 991 wakeup((caddr_t)semaptr); 992 #ifdef SEM_DEBUG 993 printf("semexit: back from wakeup\n"); 994 #endif 995 } 996 } 997 998 /* 999 * Deallocate the undo vector. 1000 */ 1001 #ifdef SEM_DEBUG 1002 printf("removing vector\n"); 1003 #endif 1004 suptr->un_proc = NULL; 1005 *supptr = suptr->un_next; 1006 } 1007