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/syscall.h> 20 #include <sys/sysent.h> 21 #include <sys/sysctl.h> 22 #include <sys/malloc.h> 23 #include <sys/jail.h> 24 25 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores"); 26 27 static void seminit __P((void)); 28 static int sysvsem_modload __P((struct module *, int, void *)); 29 static int semunload __P((void)); 30 static void semexit_myhook __P((struct proc *p)); 31 static int sysctl_sema __P((SYSCTL_HANDLER_ARGS)); 32 33 #ifndef _SYS_SYSPROTO_H_ 34 struct __semctl_args; 35 int __semctl __P((struct proc *p, struct __semctl_args *uap)); 36 struct semget_args; 37 int semget __P((struct proc *p, struct semget_args *uap)); 38 struct semop_args; 39 int semop __P((struct proc *p, struct semop_args *uap)); 40 #endif 41 42 static struct sem_undo *semu_alloc __P((struct proc *p)); 43 static int semundo_adjust __P((struct proc *p, struct sem_undo **supptr, 44 int semid, int semnum, int adjval)); 45 static void semundo_clear __P((int semid, int semnum)); 46 47 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 48 static sy_call_t *semcalls[] = { 49 (sy_call_t *)__semctl, (sy_call_t *)semget, 50 (sy_call_t *)semop 51 }; 52 53 static int semtot = 0; 54 static struct semid_ds *sema; /* semaphore id pool */ 55 static struct sem *sem; /* semaphore pool */ 56 static struct sem_undo *semu_list; /* list of active undo structures */ 57 static int *semu; /* undo structure pool */ 58 59 struct sem { 60 u_short semval; /* semaphore value */ 61 pid_t sempid; /* pid of last operation */ 62 u_short semncnt; /* # awaiting semval > cval */ 63 u_short semzcnt; /* # awaiting semval = 0 */ 64 }; 65 66 /* 67 * Undo structure (one per process) 68 */ 69 struct sem_undo { 70 struct sem_undo *un_next; /* ptr to next active undo structure */ 71 struct proc *un_proc; /* owner of this structure */ 72 short un_cnt; /* # of active entries */ 73 struct undo { 74 short un_adjval; /* adjust on exit values */ 75 short un_num; /* semaphore # */ 76 int un_id; /* semid */ 77 } un_ent[1]; /* undo entries */ 78 }; 79 80 /* 81 * Configuration parameters 82 */ 83 #ifndef SEMMNI 84 #define SEMMNI 10 /* # of semaphore identifiers */ 85 #endif 86 #ifndef SEMMNS 87 #define SEMMNS 60 /* # of semaphores in system */ 88 #endif 89 #ifndef SEMUME 90 #define SEMUME 10 /* max # of undo entries per process */ 91 #endif 92 #ifndef SEMMNU 93 #define SEMMNU 30 /* # of undo structures in system */ 94 #endif 95 96 /* shouldn't need tuning */ 97 #ifndef SEMMAP 98 #define SEMMAP 30 /* # of entries in semaphore map */ 99 #endif 100 #ifndef SEMMSL 101 #define SEMMSL SEMMNS /* max # of semaphores per id */ 102 #endif 103 #ifndef SEMOPM 104 #define SEMOPM 100 /* max # of operations per semop call */ 105 #endif 106 107 #define SEMVMX 32767 /* semaphore maximum value */ 108 #define SEMAEM 16384 /* adjust on exit max value */ 109 110 /* 111 * Due to the way semaphore memory is allocated, we have to ensure that 112 * SEMUSZ is properly aligned. 113 */ 114 115 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1)) 116 117 /* actual size of an undo structure */ 118 #define SEMUSZ SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME])) 119 120 /* 121 * Macro to find a particular sem_undo vector 122 */ 123 #define SEMU(ix) ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz)) 124 125 /* 126 * semaphore info struct 127 */ 128 struct seminfo seminfo = { 129 SEMMAP, /* # of entries in semaphore map */ 130 SEMMNI, /* # of semaphore identifiers */ 131 SEMMNS, /* # of semaphores in system */ 132 SEMMNU, /* # of undo structures in system */ 133 SEMMSL, /* max # of semaphores per id */ 134 SEMOPM, /* max # of operations per semop call */ 135 SEMUME, /* max # of undo entries per process */ 136 SEMUSZ, /* size in bytes of undo structure */ 137 SEMVMX, /* semaphore maximum value */ 138 SEMAEM /* adjust on exit max value */ 139 }; 140 141 SYSCTL_DECL(_kern_ipc); 142 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, ""); 143 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0, ""); 144 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0, ""); 145 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0, ""); 146 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, ""); 147 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0, ""); 148 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0, ""); 149 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0, ""); 150 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, ""); 151 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, ""); 152 SYSCTL_PROC(_kern_ipc, OID_AUTO, sema, CTLFLAG_RD, 153 NULL, 0, sysctl_sema, "", ""); 154 155 #if 0 156 RO seminfo.semmap /* SEMMAP unused */ 157 RO seminfo.semmni 158 RO seminfo.semmns 159 RO seminfo.semmnu /* undo entries per system */ 160 RW seminfo.semmsl 161 RO seminfo.semopm /* SEMOPM unused */ 162 RO seminfo.semume 163 RO seminfo.semusz /* param - derived from SEMUME for per-proc sizeof */ 164 RO seminfo.semvmx /* SEMVMX unused - user param */ 165 RO seminfo.semaem /* SEMAEM unused - user param */ 166 #endif 167 168 static void 169 seminit(void) 170 { 171 register int i; 172 173 sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK); 174 if (sem == NULL) 175 panic("sem is NULL"); 176 sema = malloc(sizeof(struct semid_ds) * seminfo.semmni, M_SEM, M_WAITOK); 177 if (sema == NULL) 178 panic("sema is NULL"); 179 semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK); 180 if (semu == NULL) 181 panic("semu is NULL"); 182 183 for (i = 0; i < seminfo.semmni; i++) { 184 sema[i].sem_base = 0; 185 sema[i].sem_perm.mode = 0; 186 } 187 for (i = 0; i < seminfo.semmnu; i++) { 188 register struct sem_undo *suptr = SEMU(i); 189 suptr->un_proc = NULL; 190 } 191 semu_list = NULL; 192 semexit_hook = &semexit_myhook; 193 } 194 195 static int 196 semunload(void) 197 { 198 199 if (semtot != 0) 200 return (EBUSY); 201 202 free(sem, M_SEM); 203 free(sema, M_SEM); 204 free(semu, M_SEM); 205 semexit_hook = NULL; 206 return (0); 207 } 208 209 static int 210 sysvsem_modload(struct module *module, int cmd, void *arg) 211 { 212 int error = 0; 213 214 switch (cmd) { 215 case MOD_LOAD: 216 seminit(); 217 break; 218 case MOD_UNLOAD: 219 error = semunload(); 220 break; 221 case MOD_SHUTDOWN: 222 break; 223 default: 224 error = EINVAL; 225 break; 226 } 227 return (error); 228 } 229 230 static moduledata_t sysvsem_mod = { 231 "sysvsem", 232 &sysvsem_modload, 233 NULL 234 }; 235 236 SYSCALL_MODULE_HELPER(semsys, 5); 237 SYSCALL_MODULE_HELPER(__semctl, 4); 238 SYSCALL_MODULE_HELPER(semget, 3); 239 SYSCALL_MODULE_HELPER(semop, 3); 240 241 DECLARE_MODULE(sysvsem, sysvsem_mod, 242 SI_SUB_SYSV_SEM, SI_ORDER_FIRST); 243 MODULE_VERSION(sysvsem, 1); 244 245 /* 246 * Entry point for all SEM calls 247 */ 248 int 249 semsys(p, uap) 250 struct proc *p; 251 /* XXX actually varargs. */ 252 struct semsys_args /* { 253 u_int which; 254 int a2; 255 int a3; 256 int a4; 257 int a5; 258 } */ *uap; 259 { 260 261 if (!jail_sysvipc_allowed && jailed(p->p_ucred)) 262 return (ENOSYS); 263 264 if (uap->which >= sizeof(semcalls)/sizeof(semcalls[0])) 265 return (EINVAL); 266 return ((*semcalls[uap->which])(p, &uap->a2)); 267 } 268 269 /* 270 * Allocate a new sem_undo structure for a process 271 * (returns ptr to structure or NULL if no more room) 272 */ 273 274 static struct sem_undo * 275 semu_alloc(p) 276 struct proc *p; 277 { 278 register int i; 279 register struct sem_undo *suptr; 280 register struct sem_undo **supptr; 281 int attempt; 282 283 /* 284 * Try twice to allocate something. 285 * (we'll purge any empty structures after the first pass so 286 * two passes are always enough) 287 */ 288 289 for (attempt = 0; attempt < 2; attempt++) { 290 /* 291 * Look for a free structure. 292 * Fill it in and return it if we find one. 293 */ 294 295 for (i = 0; i < seminfo.semmnu; i++) { 296 suptr = SEMU(i); 297 if (suptr->un_proc == NULL) { 298 suptr->un_next = semu_list; 299 semu_list = suptr; 300 suptr->un_cnt = 0; 301 suptr->un_proc = p; 302 return(suptr); 303 } 304 } 305 306 /* 307 * We didn't find a free one, if this is the first attempt 308 * then try to free some structures. 309 */ 310 311 if (attempt == 0) { 312 /* All the structures are in use - try to free some */ 313 int did_something = 0; 314 315 supptr = &semu_list; 316 while ((suptr = *supptr) != NULL) { 317 if (suptr->un_cnt == 0) { 318 suptr->un_proc = NULL; 319 *supptr = suptr->un_next; 320 did_something = 1; 321 } else 322 supptr = &(suptr->un_next); 323 } 324 325 /* If we didn't free anything then just give-up */ 326 if (!did_something) 327 return(NULL); 328 } else { 329 /* 330 * The second pass failed even though we freed 331 * something after the first pass! 332 * This is IMPOSSIBLE! 333 */ 334 panic("semu_alloc - second attempt failed"); 335 } 336 } 337 return (NULL); 338 } 339 340 /* 341 * Adjust a particular entry for a particular proc 342 */ 343 344 static int 345 semundo_adjust(p, supptr, semid, semnum, adjval) 346 register struct proc *p; 347 struct sem_undo **supptr; 348 int semid, semnum; 349 int adjval; 350 { 351 register struct sem_undo *suptr; 352 register struct undo *sunptr; 353 int i; 354 355 /* Look for and remember the sem_undo if the caller doesn't provide 356 it */ 357 358 suptr = *supptr; 359 if (suptr == NULL) { 360 for (suptr = semu_list; suptr != NULL; 361 suptr = suptr->un_next) { 362 if (suptr->un_proc == p) { 363 *supptr = suptr; 364 break; 365 } 366 } 367 if (suptr == NULL) { 368 if (adjval == 0) 369 return(0); 370 suptr = semu_alloc(p); 371 if (suptr == NULL) 372 return(ENOSPC); 373 *supptr = suptr; 374 } 375 } 376 377 /* 378 * Look for the requested entry and adjust it (delete if adjval becomes 379 * 0). 380 */ 381 sunptr = &suptr->un_ent[0]; 382 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 383 if (sunptr->un_id != semid || sunptr->un_num != semnum) 384 continue; 385 if (adjval == 0) 386 sunptr->un_adjval = 0; 387 else 388 sunptr->un_adjval += adjval; 389 if (sunptr->un_adjval == 0) { 390 suptr->un_cnt--; 391 if (i < suptr->un_cnt) 392 suptr->un_ent[i] = 393 suptr->un_ent[suptr->un_cnt]; 394 } 395 return(0); 396 } 397 398 /* Didn't find the right entry - create it */ 399 if (adjval == 0) 400 return(0); 401 if (suptr->un_cnt != seminfo.semume) { 402 sunptr = &suptr->un_ent[suptr->un_cnt]; 403 suptr->un_cnt++; 404 sunptr->un_adjval = adjval; 405 sunptr->un_id = semid; sunptr->un_num = semnum; 406 } else 407 return(EINVAL); 408 return(0); 409 } 410 411 static void 412 semundo_clear(semid, semnum) 413 int semid, semnum; 414 { 415 register struct sem_undo *suptr; 416 417 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { 418 register struct undo *sunptr = &suptr->un_ent[0]; 419 register int i = 0; 420 421 while (i < suptr->un_cnt) { 422 if (sunptr->un_id == semid) { 423 if (semnum == -1 || sunptr->un_num == semnum) { 424 suptr->un_cnt--; 425 if (i < suptr->un_cnt) { 426 suptr->un_ent[i] = 427 suptr->un_ent[suptr->un_cnt]; 428 continue; 429 } 430 } 431 if (semnum != -1) 432 break; 433 } 434 i++, sunptr++; 435 } 436 } 437 } 438 439 /* 440 * Note that the user-mode half of this passes a union, not a pointer 441 */ 442 #ifndef _SYS_SYSPROTO_H_ 443 struct __semctl_args { 444 int semid; 445 int semnum; 446 int cmd; 447 union semun *arg; 448 }; 449 #endif 450 451 int 452 __semctl(p, uap) 453 struct proc *p; 454 register struct __semctl_args *uap; 455 { 456 int semid = uap->semid; 457 int semnum = uap->semnum; 458 int cmd = uap->cmd; 459 union semun *arg = uap->arg; 460 union semun real_arg; 461 struct ucred *cred = p->p_ucred; 462 int i, rval, eval; 463 struct semid_ds sbuf; 464 register struct semid_ds *semaptr; 465 466 #ifdef SEM_DEBUG 467 printf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg); 468 #endif 469 470 if (!jail_sysvipc_allowed && jailed(p->p_ucred)) 471 return (ENOSYS); 472 473 semid = IPCID_TO_IX(semid); 474 if (semid < 0 || semid >= seminfo.semmsl) 475 return(EINVAL); 476 477 semaptr = &sema[semid]; 478 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 479 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 480 return(EINVAL); 481 482 eval = 0; 483 rval = 0; 484 485 switch (cmd) { 486 case IPC_RMID: 487 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M))) 488 return(eval); 489 semaptr->sem_perm.cuid = cred->cr_uid; 490 semaptr->sem_perm.uid = cred->cr_uid; 491 semtot -= semaptr->sem_nsems; 492 for (i = semaptr->sem_base - sem; i < semtot; i++) 493 sem[i] = sem[i + semaptr->sem_nsems]; 494 for (i = 0; i < seminfo.semmni; i++) { 495 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 496 sema[i].sem_base > semaptr->sem_base) 497 sema[i].sem_base -= semaptr->sem_nsems; 498 } 499 semaptr->sem_perm.mode = 0; 500 semundo_clear(semid, -1); 501 wakeup((caddr_t)semaptr); 502 break; 503 504 case IPC_SET: 505 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M))) 506 return(eval); 507 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 508 return(eval); 509 if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf, 510 sizeof(sbuf))) != 0) 511 return(eval); 512 semaptr->sem_perm.uid = sbuf.sem_perm.uid; 513 semaptr->sem_perm.gid = sbuf.sem_perm.gid; 514 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 515 (sbuf.sem_perm.mode & 0777); 516 semaptr->sem_ctime = time_second; 517 break; 518 519 case IPC_STAT: 520 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 521 return(eval); 522 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 523 return(eval); 524 eval = copyout((caddr_t)semaptr, real_arg.buf, 525 sizeof(struct semid_ds)); 526 break; 527 528 case GETNCNT: 529 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 530 return(eval); 531 if (semnum < 0 || semnum >= semaptr->sem_nsems) 532 return(EINVAL); 533 rval = semaptr->sem_base[semnum].semncnt; 534 break; 535 536 case GETPID: 537 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 538 return(eval); 539 if (semnum < 0 || semnum >= semaptr->sem_nsems) 540 return(EINVAL); 541 rval = semaptr->sem_base[semnum].sempid; 542 break; 543 544 case GETVAL: 545 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 546 return(eval); 547 if (semnum < 0 || semnum >= semaptr->sem_nsems) 548 return(EINVAL); 549 rval = semaptr->sem_base[semnum].semval; 550 break; 551 552 case GETALL: 553 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 554 return(eval); 555 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 556 return(eval); 557 for (i = 0; i < semaptr->sem_nsems; i++) { 558 eval = copyout((caddr_t)&semaptr->sem_base[i].semval, 559 &real_arg.array[i], sizeof(real_arg.array[0])); 560 if (eval != 0) 561 break; 562 } 563 break; 564 565 case GETZCNT: 566 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 567 return(eval); 568 if (semnum < 0 || semnum >= semaptr->sem_nsems) 569 return(EINVAL); 570 rval = semaptr->sem_base[semnum].semzcnt; 571 break; 572 573 case SETVAL: 574 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) 575 return(eval); 576 if (semnum < 0 || semnum >= semaptr->sem_nsems) 577 return(EINVAL); 578 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 579 return(eval); 580 semaptr->sem_base[semnum].semval = real_arg.val; 581 semundo_clear(semid, semnum); 582 wakeup((caddr_t)semaptr); 583 break; 584 585 case SETALL: 586 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) 587 return(eval); 588 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 589 return(eval); 590 for (i = 0; i < semaptr->sem_nsems; i++) { 591 eval = copyin(&real_arg.array[i], 592 (caddr_t)&semaptr->sem_base[i].semval, 593 sizeof(real_arg.array[0])); 594 if (eval != 0) 595 break; 596 } 597 semundo_clear(semid, -1); 598 wakeup((caddr_t)semaptr); 599 break; 600 601 default: 602 return(EINVAL); 603 } 604 605 if (eval == 0) 606 p->p_retval[0] = rval; 607 return(eval); 608 } 609 610 #ifndef _SYS_SYSPROTO_H_ 611 struct semget_args { 612 key_t key; 613 int nsems; 614 int semflg; 615 }; 616 #endif 617 618 int 619 semget(p, uap) 620 struct proc *p; 621 register struct semget_args *uap; 622 { 623 int semid, eval; 624 int key = uap->key; 625 int nsems = uap->nsems; 626 int semflg = uap->semflg; 627 struct ucred *cred = p->p_ucred; 628 629 #ifdef SEM_DEBUG 630 printf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg); 631 #endif 632 633 if (!jail_sysvipc_allowed && jailed(p->p_ucred)) 634 return (ENOSYS); 635 636 if (key != IPC_PRIVATE) { 637 for (semid = 0; semid < seminfo.semmni; semid++) { 638 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 639 sema[semid].sem_perm.key == key) 640 break; 641 } 642 if (semid < seminfo.semmni) { 643 #ifdef SEM_DEBUG 644 printf("found public key\n"); 645 #endif 646 if ((eval = ipcperm(p, &sema[semid].sem_perm, 647 semflg & 0700))) 648 return(eval); 649 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 650 #ifdef SEM_DEBUG 651 printf("too small\n"); 652 #endif 653 return(EINVAL); 654 } 655 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 656 #ifdef SEM_DEBUG 657 printf("not exclusive\n"); 658 #endif 659 return(EEXIST); 660 } 661 goto found; 662 } 663 } 664 665 #ifdef SEM_DEBUG 666 printf("need to allocate the semid_ds\n"); 667 #endif 668 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 669 if (nsems <= 0 || nsems > seminfo.semmsl) { 670 #ifdef SEM_DEBUG 671 printf("nsems out of range (0<%d<=%d)\n", nsems, 672 seminfo.semmsl); 673 #endif 674 return(EINVAL); 675 } 676 if (nsems > seminfo.semmns - semtot) { 677 #ifdef SEM_DEBUG 678 printf("not enough semaphores left (need %d, got %d)\n", 679 nsems, seminfo.semmns - semtot); 680 #endif 681 return(ENOSPC); 682 } 683 for (semid = 0; semid < seminfo.semmni; semid++) { 684 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 685 break; 686 } 687 if (semid == seminfo.semmni) { 688 #ifdef SEM_DEBUG 689 printf("no more semid_ds's available\n"); 690 #endif 691 return(ENOSPC); 692 } 693 #ifdef SEM_DEBUG 694 printf("semid %d is available\n", semid); 695 #endif 696 sema[semid].sem_perm.key = key; 697 sema[semid].sem_perm.cuid = cred->cr_uid; 698 sema[semid].sem_perm.uid = cred->cr_uid; 699 sema[semid].sem_perm.cgid = cred->cr_gid; 700 sema[semid].sem_perm.gid = cred->cr_gid; 701 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 702 sema[semid].sem_perm.seq = 703 (sema[semid].sem_perm.seq + 1) & 0x7fff; 704 sema[semid].sem_nsems = nsems; 705 sema[semid].sem_otime = 0; 706 sema[semid].sem_ctime = time_second; 707 sema[semid].sem_base = &sem[semtot]; 708 semtot += nsems; 709 bzero(sema[semid].sem_base, 710 sizeof(sema[semid].sem_base[0])*nsems); 711 #ifdef SEM_DEBUG 712 printf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base, 713 &sem[semtot]); 714 #endif 715 } else { 716 #ifdef SEM_DEBUG 717 printf("didn't find it and wasn't asked to create it\n"); 718 #endif 719 return(ENOENT); 720 } 721 722 found: 723 p->p_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 724 return(0); 725 } 726 727 #ifndef _SYS_SYSPROTO_H_ 728 struct semop_args { 729 int semid; 730 struct sembuf *sops; 731 int nsops; 732 }; 733 #endif 734 735 int 736 semop(p, uap) 737 struct proc *p; 738 register struct semop_args *uap; 739 { 740 int semid = uap->semid; 741 int nsops = uap->nsops; 742 struct sembuf sops[MAX_SOPS]; 743 register struct semid_ds *semaptr; 744 register struct sembuf *sopptr; 745 register struct sem *semptr; 746 struct sem_undo *suptr = NULL; 747 int i, j, eval; 748 int do_wakeup, do_undos; 749 750 #ifdef SEM_DEBUG 751 printf("call to semop(%d, 0x%x, %d)\n", semid, sops, nsops); 752 #endif 753 754 if (!jail_sysvipc_allowed && jailed(p->p_ucred)) 755 return (ENOSYS); 756 757 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 758 759 if (semid < 0 || semid >= seminfo.semmsl) 760 return(EINVAL); 761 762 semaptr = &sema[semid]; 763 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 764 return(EINVAL); 765 if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 766 return(EINVAL); 767 768 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) { 769 #ifdef SEM_DEBUG 770 printf("eval = %d from ipaccess\n", eval); 771 #endif 772 return(eval); 773 } 774 775 if (nsops > MAX_SOPS) { 776 #ifdef SEM_DEBUG 777 printf("too many sops (max=%d, nsops=%d)\n", MAX_SOPS, nsops); 778 #endif 779 return(E2BIG); 780 } 781 782 if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) { 783 #ifdef SEM_DEBUG 784 printf("eval = %d from copyin(%08x, %08x, %d)\n", eval, 785 uap->sops, &sops, nsops * sizeof(sops[0])); 786 #endif 787 return(eval); 788 } 789 790 /* 791 * Loop trying to satisfy the vector of requests. 792 * If we reach a point where we must wait, any requests already 793 * performed are rolled back and we go to sleep until some other 794 * process wakes us up. At this point, we start all over again. 795 * 796 * This ensures that from the perspective of other tasks, a set 797 * of requests is atomic (never partially satisfied). 798 */ 799 do_undos = 0; 800 801 for (;;) { 802 do_wakeup = 0; 803 804 for (i = 0; i < nsops; i++) { 805 sopptr = &sops[i]; 806 807 if (sopptr->sem_num >= semaptr->sem_nsems) 808 return(EFBIG); 809 810 semptr = &semaptr->sem_base[sopptr->sem_num]; 811 812 #ifdef SEM_DEBUG 813 printf("semop: semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n", 814 semaptr, semaptr->sem_base, semptr, 815 sopptr->sem_num, semptr->semval, sopptr->sem_op, 816 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait"); 817 #endif 818 819 if (sopptr->sem_op < 0) { 820 if (semptr->semval + sopptr->sem_op < 0) { 821 #ifdef SEM_DEBUG 822 printf("semop: can't do it now\n"); 823 #endif 824 break; 825 } else { 826 semptr->semval += sopptr->sem_op; 827 if (semptr->semval == 0 && 828 semptr->semzcnt > 0) 829 do_wakeup = 1; 830 } 831 if (sopptr->sem_flg & SEM_UNDO) 832 do_undos = 1; 833 } else if (sopptr->sem_op == 0) { 834 if (semptr->semval > 0) { 835 #ifdef SEM_DEBUG 836 printf("semop: not zero now\n"); 837 #endif 838 break; 839 } 840 } else { 841 if (semptr->semncnt > 0) 842 do_wakeup = 1; 843 semptr->semval += sopptr->sem_op; 844 if (sopptr->sem_flg & SEM_UNDO) 845 do_undos = 1; 846 } 847 } 848 849 /* 850 * Did we get through the entire vector? 851 */ 852 if (i >= nsops) 853 goto done; 854 855 /* 856 * No ... rollback anything that we've already done 857 */ 858 #ifdef SEM_DEBUG 859 printf("semop: rollback 0 through %d\n", i-1); 860 #endif 861 for (j = 0; j < i; j++) 862 semaptr->sem_base[sops[j].sem_num].semval -= 863 sops[j].sem_op; 864 865 /* 866 * If the request that we couldn't satisfy has the 867 * NOWAIT flag set then return with EAGAIN. 868 */ 869 if (sopptr->sem_flg & IPC_NOWAIT) 870 return(EAGAIN); 871 872 if (sopptr->sem_op == 0) 873 semptr->semzcnt++; 874 else 875 semptr->semncnt++; 876 877 #ifdef SEM_DEBUG 878 printf("semop: good night!\n"); 879 #endif 880 eval = tsleep((caddr_t)semaptr, (PZERO - 4) | PCATCH, 881 "semwait", 0); 882 #ifdef SEM_DEBUG 883 printf("semop: good morning (eval=%d)!\n", eval); 884 #endif 885 886 suptr = NULL; /* sem_undo may have been reallocated */ 887 888 if (eval != 0) 889 return(EINTR); 890 #ifdef SEM_DEBUG 891 printf("semop: good morning!\n"); 892 #endif 893 894 /* 895 * Make sure that the semaphore still exists 896 */ 897 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 898 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 899 return(EIDRM); 900 901 /* 902 * The semaphore is still alive. Readjust the count of 903 * waiting processes. 904 */ 905 if (sopptr->sem_op == 0) 906 semptr->semzcnt--; 907 else 908 semptr->semncnt--; 909 } 910 911 done: 912 /* 913 * Process any SEM_UNDO requests. 914 */ 915 if (do_undos) { 916 for (i = 0; i < nsops; i++) { 917 /* 918 * We only need to deal with SEM_UNDO's for non-zero 919 * op's. 920 */ 921 int adjval; 922 923 if ((sops[i].sem_flg & SEM_UNDO) == 0) 924 continue; 925 adjval = sops[i].sem_op; 926 if (adjval == 0) 927 continue; 928 eval = semundo_adjust(p, &suptr, semid, 929 sops[i].sem_num, -adjval); 930 if (eval == 0) 931 continue; 932 933 /* 934 * Oh-Oh! We ran out of either sem_undo's or undo's. 935 * Rollback the adjustments to this point and then 936 * rollback the semaphore ups and down so we can return 937 * with an error with all structures restored. We 938 * rollback the undo's in the exact reverse order that 939 * we applied them. This guarantees that we won't run 940 * out of space as we roll things back out. 941 */ 942 for (j = i - 1; j >= 0; j--) { 943 if ((sops[j].sem_flg & SEM_UNDO) == 0) 944 continue; 945 adjval = sops[j].sem_op; 946 if (adjval == 0) 947 continue; 948 if (semundo_adjust(p, &suptr, semid, 949 sops[j].sem_num, adjval) != 0) 950 panic("semop - can't undo undos"); 951 } 952 953 for (j = 0; j < nsops; j++) 954 semaptr->sem_base[sops[j].sem_num].semval -= 955 sops[j].sem_op; 956 957 #ifdef SEM_DEBUG 958 printf("eval = %d from semundo_adjust\n", eval); 959 #endif 960 return(eval); 961 } /* loop through the sops */ 962 } /* if (do_undos) */ 963 964 /* We're definitely done - set the sempid's */ 965 for (i = 0; i < nsops; i++) { 966 sopptr = &sops[i]; 967 semptr = &semaptr->sem_base[sopptr->sem_num]; 968 semptr->sempid = p->p_pid; 969 } 970 971 /* Do a wakeup if any semaphore was up'd. */ 972 if (do_wakeup) { 973 #ifdef SEM_DEBUG 974 printf("semop: doing wakeup\n"); 975 #endif 976 wakeup((caddr_t)semaptr); 977 #ifdef SEM_DEBUG 978 printf("semop: back from wakeup\n"); 979 #endif 980 } 981 #ifdef SEM_DEBUG 982 printf("semop: done\n"); 983 #endif 984 p->p_retval[0] = 0; 985 return(0); 986 } 987 988 /* 989 * Go through the undo structures for this process and apply the adjustments to 990 * semaphores. 991 */ 992 static void 993 semexit_myhook(p) 994 struct proc *p; 995 { 996 register struct sem_undo *suptr; 997 register struct sem_undo **supptr; 998 int did_something; 999 1000 did_something = 0; 1001 1002 /* 1003 * Go through the chain of undo vectors looking for one 1004 * associated with this process. 1005 */ 1006 1007 for (supptr = &semu_list; (suptr = *supptr) != NULL; 1008 supptr = &suptr->un_next) { 1009 if (suptr->un_proc == p) 1010 break; 1011 } 1012 1013 if (suptr == NULL) 1014 return; 1015 1016 #ifdef SEM_DEBUG 1017 printf("proc @%08x has undo structure with %d entries\n", p, 1018 suptr->un_cnt); 1019 #endif 1020 1021 /* 1022 * If there are any active undo elements then process them. 1023 */ 1024 if (suptr->un_cnt > 0) { 1025 int ix; 1026 1027 for (ix = 0; ix < suptr->un_cnt; ix++) { 1028 int semid = suptr->un_ent[ix].un_id; 1029 int semnum = suptr->un_ent[ix].un_num; 1030 int adjval = suptr->un_ent[ix].un_adjval; 1031 struct semid_ds *semaptr; 1032 1033 semaptr = &sema[semid]; 1034 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 1035 panic("semexit - semid not allocated"); 1036 if (semnum >= semaptr->sem_nsems) 1037 panic("semexit - semnum out of range"); 1038 1039 #ifdef SEM_DEBUG 1040 printf("semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n", 1041 suptr->un_proc, suptr->un_ent[ix].un_id, 1042 suptr->un_ent[ix].un_num, 1043 suptr->un_ent[ix].un_adjval, 1044 semaptr->sem_base[semnum].semval); 1045 #endif 1046 1047 if (adjval < 0) { 1048 if (semaptr->sem_base[semnum].semval < -adjval) 1049 semaptr->sem_base[semnum].semval = 0; 1050 else 1051 semaptr->sem_base[semnum].semval += 1052 adjval; 1053 } else 1054 semaptr->sem_base[semnum].semval += adjval; 1055 1056 wakeup((caddr_t)semaptr); 1057 #ifdef SEM_DEBUG 1058 printf("semexit: back from wakeup\n"); 1059 #endif 1060 } 1061 } 1062 1063 /* 1064 * Deallocate the undo vector. 1065 */ 1066 #ifdef SEM_DEBUG 1067 printf("removing vector\n"); 1068 #endif 1069 suptr->un_proc = NULL; 1070 *supptr = suptr->un_next; 1071 } 1072 1073 static int 1074 sysctl_sema(SYSCTL_HANDLER_ARGS) 1075 { 1076 1077 return (SYSCTL_OUT(req, sema, 1078 sizeof(struct semid_ds) * seminfo.semmni)); 1079 } 1080