1 /* $FreeBSD: src/sys/kern/sysv_sem.c,v 1.24.2.8 2002/10/22 20:45:03 fjoe Exp $ */ 2 /* $DragonFly: src/sys/kern/sysv_sem.c,v 1.2 2003/06/17 04:28:41 dillon Exp $ */ 3 4 /* 5 * Implementation of SVID semaphores 6 * 7 * Author: Daniel Boulet 8 * 9 * This software is provided ``AS IS'' without any warranties of any kind. 10 */ 11 12 #include "opt_sysvipc.h" 13 14 #include <sys/param.h> 15 #include <sys/systm.h> 16 #include <sys/sysproto.h> 17 #include <sys/kernel.h> 18 #include <sys/proc.h> 19 #include <sys/sem.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 29 #ifndef _SYS_SYSPROTO_H_ 30 struct __semctl_args; 31 int __semctl __P((struct proc *p, struct __semctl_args *uap)); 32 struct semget_args; 33 int semget __P((struct proc *p, struct semget_args *uap)); 34 struct semop_args; 35 int semop __P((struct proc *p, struct semop_args *uap)); 36 #endif 37 38 static struct sem_undo *semu_alloc __P((struct proc *p)); 39 static int semundo_adjust __P((struct proc *p, struct sem_undo **supptr, 40 int semid, int semnum, int adjval)); 41 static void semundo_clear __P((int semid, int semnum)); 42 43 /* XXX casting to (sy_call_t *) is bogus, as usual. */ 44 static sy_call_t *semcalls[] = { 45 (sy_call_t *)__semctl, (sy_call_t *)semget, 46 (sy_call_t *)semop 47 }; 48 49 static int semtot = 0; 50 static struct semid_ds *sema; /* semaphore id pool */ 51 static struct sem *sem; /* semaphore pool */ 52 static struct sem_undo *semu_list; /* list of active undo structures */ 53 static int *semu; /* undo structure pool */ 54 55 struct sem { 56 u_short semval; /* semaphore value */ 57 pid_t sempid; /* pid of last operation */ 58 u_short semncnt; /* # awaiting semval > cval */ 59 u_short semzcnt; /* # awaiting semval = 0 */ 60 }; 61 62 /* 63 * Undo structure (one per process) 64 */ 65 struct sem_undo { 66 struct sem_undo *un_next; /* ptr to next active undo structure */ 67 struct proc *un_proc; /* owner of this structure */ 68 short un_cnt; /* # of active entries */ 69 struct undo { 70 short un_adjval; /* adjust on exit values */ 71 short un_num; /* semaphore # */ 72 int un_id; /* semid */ 73 } un_ent[1]; /* undo entries */ 74 }; 75 76 /* 77 * Configuration parameters 78 */ 79 #ifndef SEMMNI 80 #define SEMMNI 10 /* # of semaphore identifiers */ 81 #endif 82 #ifndef SEMMNS 83 #define SEMMNS 60 /* # of semaphores in system */ 84 #endif 85 #ifndef SEMUME 86 #define SEMUME 10 /* max # of undo entries per process */ 87 #endif 88 #ifndef SEMMNU 89 #define SEMMNU 30 /* # of undo structures in system */ 90 #endif 91 92 /* shouldn't need tuning */ 93 #ifndef SEMMAP 94 #define SEMMAP 30 /* # of entries in semaphore map */ 95 #endif 96 #ifndef SEMMSL 97 #define SEMMSL SEMMNS /* max # of semaphores per id */ 98 #endif 99 #ifndef SEMOPM 100 #define SEMOPM 100 /* max # of operations per semop call */ 101 #endif 102 103 #define SEMVMX 32767 /* semaphore maximum value */ 104 #define SEMAEM 16384 /* adjust on exit max value */ 105 106 /* 107 * Due to the way semaphore memory is allocated, we have to ensure that 108 * SEMUSZ is properly aligned. 109 */ 110 111 #define SEM_ALIGN(bytes) (((bytes) + (sizeof(long) - 1)) & ~(sizeof(long) - 1)) 112 113 /* actual size of an undo structure */ 114 #define SEMUSZ SEM_ALIGN(offsetof(struct sem_undo, un_ent[SEMUME])) 115 116 /* 117 * Macro to find a particular sem_undo vector 118 */ 119 #define SEMU(ix) ((struct sem_undo *)(((intptr_t)semu)+ix * seminfo.semusz)) 120 121 /* 122 * semaphore info struct 123 */ 124 struct seminfo seminfo = { 125 SEMMAP, /* # of entries in semaphore map */ 126 SEMMNI, /* # of semaphore identifiers */ 127 SEMMNS, /* # of semaphores in system */ 128 SEMMNU, /* # of undo structures in system */ 129 SEMMSL, /* max # of semaphores per id */ 130 SEMOPM, /* max # of operations per semop call */ 131 SEMUME, /* max # of undo entries per process */ 132 SEMUSZ, /* size in bytes of undo structure */ 133 SEMVMX, /* semaphore maximum value */ 134 SEMAEM /* adjust on exit max value */ 135 }; 136 137 TUNABLE_INT("kern.ipc.semmap", &seminfo.semmap); 138 TUNABLE_INT("kern.ipc.semmni", &seminfo.semmni); 139 TUNABLE_INT("kern.ipc.semmns", &seminfo.semmns); 140 TUNABLE_INT("kern.ipc.semmnu", &seminfo.semmnu); 141 TUNABLE_INT("kern.ipc.semmsl", &seminfo.semmsl); 142 TUNABLE_INT("kern.ipc.semopm", &seminfo.semopm); 143 TUNABLE_INT("kern.ipc.semume", &seminfo.semume); 144 TUNABLE_INT("kern.ipc.semusz", &seminfo.semusz); 145 TUNABLE_INT("kern.ipc.semvmx", &seminfo.semvmx); 146 TUNABLE_INT("kern.ipc.semaem", &seminfo.semaem); 147 148 SYSCTL_DECL(_kern_ipc); 149 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, ""); 150 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0, ""); 151 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0, ""); 152 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0, ""); 153 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, ""); 154 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0, ""); 155 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0, ""); 156 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0, ""); 157 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, ""); 158 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, ""); 159 160 #if 0 161 RO seminfo.semmap /* SEMMAP unused */ 162 RO seminfo.semmni 163 RO seminfo.semmns 164 RO seminfo.semmnu /* undo entries per system */ 165 RW seminfo.semmsl 166 RO seminfo.semopm /* SEMOPM unused */ 167 RO seminfo.semume 168 RO seminfo.semusz /* param - derived from SEMUME for per-proc sizeof */ 169 RO seminfo.semvmx /* SEMVMX unused - user param */ 170 RO seminfo.semaem /* SEMAEM unused - user param */ 171 #endif 172 173 static void 174 seminit(dummy) 175 void *dummy; 176 { 177 register int i; 178 179 sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK); 180 if (sem == NULL) 181 panic("sem is NULL"); 182 sema = malloc(sizeof(struct semid_ds) * seminfo.semmni, M_SEM, M_WAITOK); 183 if (sema == NULL) 184 panic("sema is NULL"); 185 semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK); 186 if (semu == NULL) 187 panic("semu is NULL"); 188 189 for (i = 0; i < seminfo.semmni; i++) { 190 sema[i].sem_base = 0; 191 sema[i].sem_perm.mode = 0; 192 } 193 for (i = 0; i < seminfo.semmnu; i++) { 194 register struct sem_undo *suptr = SEMU(i); 195 suptr->un_proc = NULL; 196 } 197 semu_list = NULL; 198 } 199 SYSINIT(sysv_sem, SI_SUB_SYSV_SEM, SI_ORDER_FIRST, seminit, NULL) 200 201 /* 202 * Entry point for all SEM calls 203 */ 204 int 205 semsys(p, uap) 206 struct proc *p; 207 /* XXX actually varargs. */ 208 struct semsys_args /* { 209 u_int which; 210 int a2; 211 int a3; 212 int a4; 213 int a5; 214 } */ *uap; 215 { 216 217 if (!jail_sysvipc_allowed && p->p_prison != NULL) 218 return (ENOSYS); 219 220 if (uap->which >= sizeof(semcalls)/sizeof(semcalls[0])) 221 return (EINVAL); 222 return ((*semcalls[uap->which])(p, &uap->a2)); 223 } 224 225 /* 226 * Allocate a new sem_undo structure for a process 227 * (returns ptr to structure or NULL if no more room) 228 */ 229 230 static struct sem_undo * 231 semu_alloc(p) 232 struct proc *p; 233 { 234 register int i; 235 register struct sem_undo *suptr; 236 register struct sem_undo **supptr; 237 int attempt; 238 239 /* 240 * Try twice to allocate something. 241 * (we'll purge any empty structures after the first pass so 242 * two passes are always enough) 243 */ 244 245 for (attempt = 0; attempt < 2; attempt++) { 246 /* 247 * Look for a free structure. 248 * Fill it in and return it if we find one. 249 */ 250 251 for (i = 0; i < seminfo.semmnu; i++) { 252 suptr = SEMU(i); 253 if (suptr->un_proc == NULL) { 254 suptr->un_next = semu_list; 255 semu_list = suptr; 256 suptr->un_cnt = 0; 257 suptr->un_proc = p; 258 return(suptr); 259 } 260 } 261 262 /* 263 * We didn't find a free one, if this is the first attempt 264 * then try to free some structures. 265 */ 266 267 if (attempt == 0) { 268 /* All the structures are in use - try to free some */ 269 int did_something = 0; 270 271 supptr = &semu_list; 272 while ((suptr = *supptr) != NULL) { 273 if (suptr->un_cnt == 0) { 274 suptr->un_proc = NULL; 275 *supptr = suptr->un_next; 276 did_something = 1; 277 } else 278 supptr = &(suptr->un_next); 279 } 280 281 /* If we didn't free anything then just give-up */ 282 if (!did_something) 283 return(NULL); 284 } else { 285 /* 286 * The second pass failed even though we freed 287 * something after the first pass! 288 * This is IMPOSSIBLE! 289 */ 290 panic("semu_alloc - second attempt failed"); 291 } 292 } 293 return (NULL); 294 } 295 296 /* 297 * Adjust a particular entry for a particular proc 298 */ 299 300 static int 301 semundo_adjust(p, supptr, semid, semnum, adjval) 302 register struct proc *p; 303 struct sem_undo **supptr; 304 int semid, semnum; 305 int adjval; 306 { 307 register struct sem_undo *suptr; 308 register struct undo *sunptr; 309 int i; 310 311 /* Look for and remember the sem_undo if the caller doesn't provide 312 it */ 313 314 suptr = *supptr; 315 if (suptr == NULL) { 316 for (suptr = semu_list; suptr != NULL; 317 suptr = suptr->un_next) { 318 if (suptr->un_proc == p) { 319 *supptr = suptr; 320 break; 321 } 322 } 323 if (suptr == NULL) { 324 if (adjval == 0) 325 return(0); 326 suptr = semu_alloc(p); 327 if (suptr == NULL) 328 return(ENOSPC); 329 *supptr = suptr; 330 } 331 } 332 333 /* 334 * Look for the requested entry and adjust it (delete if adjval becomes 335 * 0). 336 */ 337 sunptr = &suptr->un_ent[0]; 338 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 339 if (sunptr->un_id != semid || sunptr->un_num != semnum) 340 continue; 341 if (adjval == 0) 342 sunptr->un_adjval = 0; 343 else 344 sunptr->un_adjval += adjval; 345 if (sunptr->un_adjval == 0) { 346 suptr->un_cnt--; 347 if (i < suptr->un_cnt) 348 suptr->un_ent[i] = 349 suptr->un_ent[suptr->un_cnt]; 350 } 351 return(0); 352 } 353 354 /* Didn't find the right entry - create it */ 355 if (adjval == 0) 356 return(0); 357 if (suptr->un_cnt != seminfo.semume) { 358 sunptr = &suptr->un_ent[suptr->un_cnt]; 359 suptr->un_cnt++; 360 sunptr->un_adjval = adjval; 361 sunptr->un_id = semid; sunptr->un_num = semnum; 362 } else 363 return(EINVAL); 364 return(0); 365 } 366 367 static void 368 semundo_clear(semid, semnum) 369 int semid, semnum; 370 { 371 register struct sem_undo *suptr; 372 373 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { 374 register struct undo *sunptr = &suptr->un_ent[0]; 375 register int i = 0; 376 377 while (i < suptr->un_cnt) { 378 if (sunptr->un_id == semid) { 379 if (semnum == -1 || sunptr->un_num == semnum) { 380 suptr->un_cnt--; 381 if (i < suptr->un_cnt) { 382 suptr->un_ent[i] = 383 suptr->un_ent[suptr->un_cnt]; 384 continue; 385 } 386 } 387 if (semnum != -1) 388 break; 389 } 390 i++, sunptr++; 391 } 392 } 393 } 394 395 /* 396 * Note that the user-mode half of this passes a union, not a pointer 397 */ 398 #ifndef _SYS_SYSPROTO_H_ 399 struct __semctl_args { 400 int semid; 401 int semnum; 402 int cmd; 403 union semun *arg; 404 }; 405 #endif 406 407 int 408 __semctl(p, uap) 409 struct proc *p; 410 register struct __semctl_args *uap; 411 { 412 int semid = uap->semid; 413 int semnum = uap->semnum; 414 int cmd = uap->cmd; 415 union semun *arg = uap->arg; 416 union semun real_arg; 417 struct ucred *cred = p->p_ucred; 418 int i, rval, eval; 419 struct semid_ds sbuf; 420 register struct semid_ds *semaptr; 421 422 #ifdef SEM_DEBUG 423 printf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg); 424 #endif 425 426 if (!jail_sysvipc_allowed && p->p_prison != NULL) 427 return (ENOSYS); 428 429 semid = IPCID_TO_IX(semid); 430 if (semid < 0 || semid >= seminfo.semmni) 431 return(EINVAL); 432 433 semaptr = &sema[semid]; 434 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 435 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 436 return(EINVAL); 437 438 eval = 0; 439 rval = 0; 440 441 switch (cmd) { 442 case IPC_RMID: 443 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M))) 444 return(eval); 445 semaptr->sem_perm.cuid = cred->cr_uid; 446 semaptr->sem_perm.uid = cred->cr_uid; 447 semtot -= semaptr->sem_nsems; 448 for (i = semaptr->sem_base - sem; i < semtot; i++) 449 sem[i] = sem[i + semaptr->sem_nsems]; 450 for (i = 0; i < seminfo.semmni; i++) { 451 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 452 sema[i].sem_base > semaptr->sem_base) 453 sema[i].sem_base -= semaptr->sem_nsems; 454 } 455 semaptr->sem_perm.mode = 0; 456 semundo_clear(semid, -1); 457 wakeup((caddr_t)semaptr); 458 break; 459 460 case IPC_SET: 461 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M))) 462 return(eval); 463 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 464 return(eval); 465 if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf, 466 sizeof(sbuf))) != 0) 467 return(eval); 468 semaptr->sem_perm.uid = sbuf.sem_perm.uid; 469 semaptr->sem_perm.gid = sbuf.sem_perm.gid; 470 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 471 (sbuf.sem_perm.mode & 0777); 472 semaptr->sem_ctime = time_second; 473 break; 474 475 case IPC_STAT: 476 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 477 return(eval); 478 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 479 return(eval); 480 eval = copyout((caddr_t)semaptr, real_arg.buf, 481 sizeof(struct semid_ds)); 482 break; 483 484 case GETNCNT: 485 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 486 return(eval); 487 if (semnum < 0 || semnum >= semaptr->sem_nsems) 488 return(EINVAL); 489 rval = semaptr->sem_base[semnum].semncnt; 490 break; 491 492 case GETPID: 493 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 494 return(eval); 495 if (semnum < 0 || semnum >= semaptr->sem_nsems) 496 return(EINVAL); 497 rval = semaptr->sem_base[semnum].sempid; 498 break; 499 500 case GETVAL: 501 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 502 return(eval); 503 if (semnum < 0 || semnum >= semaptr->sem_nsems) 504 return(EINVAL); 505 rval = semaptr->sem_base[semnum].semval; 506 break; 507 508 case GETALL: 509 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 510 return(eval); 511 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 512 return(eval); 513 for (i = 0; i < semaptr->sem_nsems; i++) { 514 eval = copyout((caddr_t)&semaptr->sem_base[i].semval, 515 &real_arg.array[i], sizeof(real_arg.array[0])); 516 if (eval != 0) 517 break; 518 } 519 break; 520 521 case GETZCNT: 522 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 523 return(eval); 524 if (semnum < 0 || semnum >= semaptr->sem_nsems) 525 return(EINVAL); 526 rval = semaptr->sem_base[semnum].semzcnt; 527 break; 528 529 case SETVAL: 530 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) 531 return(eval); 532 if (semnum < 0 || semnum >= semaptr->sem_nsems) 533 return(EINVAL); 534 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 535 return(eval); 536 semaptr->sem_base[semnum].semval = real_arg.val; 537 semundo_clear(semid, semnum); 538 wakeup((caddr_t)semaptr); 539 break; 540 541 case SETALL: 542 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) 543 return(eval); 544 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 545 return(eval); 546 for (i = 0; i < semaptr->sem_nsems; i++) { 547 eval = copyin(&real_arg.array[i], 548 (caddr_t)&semaptr->sem_base[i].semval, 549 sizeof(real_arg.array[0])); 550 if (eval != 0) 551 break; 552 } 553 semundo_clear(semid, -1); 554 wakeup((caddr_t)semaptr); 555 break; 556 557 default: 558 return(EINVAL); 559 } 560 561 if (eval == 0) 562 p->p_retval[0] = rval; 563 return(eval); 564 } 565 566 #ifndef _SYS_SYSPROTO_H_ 567 struct semget_args { 568 key_t key; 569 int nsems; 570 int semflg; 571 }; 572 #endif 573 574 int 575 semget(p, uap) 576 struct proc *p; 577 register struct semget_args *uap; 578 { 579 int semid, eval; 580 int key = uap->key; 581 int nsems = uap->nsems; 582 int semflg = uap->semflg; 583 struct ucred *cred = p->p_ucred; 584 585 #ifdef SEM_DEBUG 586 printf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg); 587 #endif 588 589 if (!jail_sysvipc_allowed && p->p_prison != NULL) 590 return (ENOSYS); 591 592 if (key != IPC_PRIVATE) { 593 for (semid = 0; semid < seminfo.semmni; semid++) { 594 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 595 sema[semid].sem_perm.key == key) 596 break; 597 } 598 if (semid < seminfo.semmni) { 599 #ifdef SEM_DEBUG 600 printf("found public key\n"); 601 #endif 602 if ((eval = ipcperm(p, &sema[semid].sem_perm, 603 semflg & 0700))) 604 return(eval); 605 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 606 #ifdef SEM_DEBUG 607 printf("too small\n"); 608 #endif 609 return(EINVAL); 610 } 611 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 612 #ifdef SEM_DEBUG 613 printf("not exclusive\n"); 614 #endif 615 return(EEXIST); 616 } 617 goto found; 618 } 619 } 620 621 #ifdef SEM_DEBUG 622 printf("need to allocate the semid_ds\n"); 623 #endif 624 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 625 if (nsems <= 0 || nsems > seminfo.semmsl) { 626 #ifdef SEM_DEBUG 627 printf("nsems out of range (0<%d<=%d)\n", nsems, 628 seminfo.semmsl); 629 #endif 630 return(EINVAL); 631 } 632 if (nsems > seminfo.semmns - semtot) { 633 #ifdef SEM_DEBUG 634 printf("not enough semaphores left (need %d, got %d)\n", 635 nsems, seminfo.semmns - semtot); 636 #endif 637 return(ENOSPC); 638 } 639 for (semid = 0; semid < seminfo.semmni; semid++) { 640 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 641 break; 642 } 643 if (semid == seminfo.semmni) { 644 #ifdef SEM_DEBUG 645 printf("no more semid_ds's available\n"); 646 #endif 647 return(ENOSPC); 648 } 649 #ifdef SEM_DEBUG 650 printf("semid %d is available\n", semid); 651 #endif 652 sema[semid].sem_perm.key = key; 653 sema[semid].sem_perm.cuid = cred->cr_uid; 654 sema[semid].sem_perm.uid = cred->cr_uid; 655 sema[semid].sem_perm.cgid = cred->cr_gid; 656 sema[semid].sem_perm.gid = cred->cr_gid; 657 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 658 sema[semid].sem_perm.seq = 659 (sema[semid].sem_perm.seq + 1) & 0x7fff; 660 sema[semid].sem_nsems = nsems; 661 sema[semid].sem_otime = 0; 662 sema[semid].sem_ctime = time_second; 663 sema[semid].sem_base = &sem[semtot]; 664 semtot += nsems; 665 bzero(sema[semid].sem_base, 666 sizeof(sema[semid].sem_base[0])*nsems); 667 #ifdef SEM_DEBUG 668 printf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base, 669 &sem[semtot]); 670 #endif 671 } else { 672 #ifdef SEM_DEBUG 673 printf("didn't find it and wasn't asked to create it\n"); 674 #endif 675 return(ENOENT); 676 } 677 678 found: 679 p->p_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 680 return(0); 681 } 682 683 #ifndef _SYS_SYSPROTO_H_ 684 struct semop_args { 685 int semid; 686 struct sembuf *sops; 687 u_int nsops; 688 }; 689 #endif 690 691 int 692 semop(p, uap) 693 struct proc *p; 694 register struct semop_args *uap; 695 { 696 int semid = uap->semid; 697 u_int nsops = uap->nsops; 698 struct sembuf sops[MAX_SOPS]; 699 register struct semid_ds *semaptr; 700 register struct sembuf *sopptr; 701 register struct sem *semptr; 702 struct sem_undo *suptr = NULL; 703 int i, j, eval; 704 int do_wakeup, do_undos; 705 706 #ifdef SEM_DEBUG 707 printf("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops); 708 #endif 709 710 if (!jail_sysvipc_allowed && p->p_prison != NULL) 711 return (ENOSYS); 712 713 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 714 715 if (semid < 0 || semid >= seminfo.semmni) 716 return(EINVAL); 717 718 semaptr = &sema[semid]; 719 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 720 return(EINVAL); 721 if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 722 return(EINVAL); 723 724 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) { 725 #ifdef SEM_DEBUG 726 printf("eval = %d from ipaccess\n", eval); 727 #endif 728 return(eval); 729 } 730 731 if (nsops > MAX_SOPS) { 732 #ifdef SEM_DEBUG 733 printf("too many sops (max=%d, nsops=%u)\n", MAX_SOPS, nsops); 734 #endif 735 return(E2BIG); 736 } 737 738 if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) { 739 #ifdef SEM_DEBUG 740 printf("eval = %d from copyin(%08x, %08x, %u)\n", eval, 741 uap->sops, &sops, nsops * sizeof(sops[0])); 742 #endif 743 return(eval); 744 } 745 746 /* 747 * Loop trying to satisfy the vector of requests. 748 * If we reach a point where we must wait, any requests already 749 * performed are rolled back and we go to sleep until some other 750 * process wakes us up. At this point, we start all over again. 751 * 752 * This ensures that from the perspective of other tasks, a set 753 * of requests is atomic (never partially satisfied). 754 */ 755 do_undos = 0; 756 757 for (;;) { 758 do_wakeup = 0; 759 760 for (i = 0; i < nsops; i++) { 761 sopptr = &sops[i]; 762 763 if (sopptr->sem_num >= semaptr->sem_nsems) 764 return(EFBIG); 765 766 semptr = &semaptr->sem_base[sopptr->sem_num]; 767 768 #ifdef SEM_DEBUG 769 printf("semop: semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n", 770 semaptr, semaptr->sem_base, semptr, 771 sopptr->sem_num, semptr->semval, sopptr->sem_op, 772 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait"); 773 #endif 774 775 if (sopptr->sem_op < 0) { 776 if (semptr->semval + sopptr->sem_op < 0) { 777 #ifdef SEM_DEBUG 778 printf("semop: can't do it now\n"); 779 #endif 780 break; 781 } else { 782 semptr->semval += sopptr->sem_op; 783 if (semptr->semval == 0 && 784 semptr->semzcnt > 0) 785 do_wakeup = 1; 786 } 787 if (sopptr->sem_flg & SEM_UNDO) 788 do_undos = 1; 789 } else if (sopptr->sem_op == 0) { 790 if (semptr->semval > 0) { 791 #ifdef SEM_DEBUG 792 printf("semop: not zero now\n"); 793 #endif 794 break; 795 } 796 } else { 797 if (semptr->semncnt > 0) 798 do_wakeup = 1; 799 semptr->semval += sopptr->sem_op; 800 if (sopptr->sem_flg & SEM_UNDO) 801 do_undos = 1; 802 } 803 } 804 805 /* 806 * Did we get through the entire vector? 807 */ 808 if (i >= nsops) 809 goto done; 810 811 /* 812 * No ... rollback anything that we've already done 813 */ 814 #ifdef SEM_DEBUG 815 printf("semop: rollback 0 through %d\n", i-1); 816 #endif 817 for (j = 0; j < i; j++) 818 semaptr->sem_base[sops[j].sem_num].semval -= 819 sops[j].sem_op; 820 821 /* 822 * If the request that we couldn't satisfy has the 823 * NOWAIT flag set then return with EAGAIN. 824 */ 825 if (sopptr->sem_flg & IPC_NOWAIT) 826 return(EAGAIN); 827 828 if (sopptr->sem_op == 0) 829 semptr->semzcnt++; 830 else 831 semptr->semncnt++; 832 833 #ifdef SEM_DEBUG 834 printf("semop: good night!\n"); 835 #endif 836 eval = tsleep((caddr_t)semaptr, (PZERO - 4) | PCATCH, 837 "semwait", 0); 838 #ifdef SEM_DEBUG 839 printf("semop: good morning (eval=%d)!\n", eval); 840 #endif 841 842 suptr = NULL; /* sem_undo may have been reallocated */ 843 844 if (eval != 0) 845 return(EINTR); 846 #ifdef SEM_DEBUG 847 printf("semop: good morning!\n"); 848 #endif 849 850 /* 851 * Make sure that the semaphore still exists 852 */ 853 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 854 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 855 return(EIDRM); 856 857 /* 858 * The semaphore is still alive. Readjust the count of 859 * waiting processes. 860 */ 861 if (sopptr->sem_op == 0) 862 semptr->semzcnt--; 863 else 864 semptr->semncnt--; 865 } 866 867 done: 868 /* 869 * Process any SEM_UNDO requests. 870 */ 871 if (do_undos) { 872 for (i = 0; i < nsops; i++) { 873 /* 874 * We only need to deal with SEM_UNDO's for non-zero 875 * op's. 876 */ 877 int adjval; 878 879 if ((sops[i].sem_flg & SEM_UNDO) == 0) 880 continue; 881 adjval = sops[i].sem_op; 882 if (adjval == 0) 883 continue; 884 eval = semundo_adjust(p, &suptr, semid, 885 sops[i].sem_num, -adjval); 886 if (eval == 0) 887 continue; 888 889 /* 890 * Oh-Oh! We ran out of either sem_undo's or undo's. 891 * Rollback the adjustments to this point and then 892 * rollback the semaphore ups and down so we can return 893 * with an error with all structures restored. We 894 * rollback the undo's in the exact reverse order that 895 * we applied them. This guarantees that we won't run 896 * out of space as we roll things back out. 897 */ 898 for (j = i - 1; j >= 0; j--) { 899 if ((sops[j].sem_flg & SEM_UNDO) == 0) 900 continue; 901 adjval = sops[j].sem_op; 902 if (adjval == 0) 903 continue; 904 if (semundo_adjust(p, &suptr, semid, 905 sops[j].sem_num, adjval) != 0) 906 panic("semop - can't undo undos"); 907 } 908 909 for (j = 0; j < nsops; j++) 910 semaptr->sem_base[sops[j].sem_num].semval -= 911 sops[j].sem_op; 912 913 #ifdef SEM_DEBUG 914 printf("eval = %d from semundo_adjust\n", eval); 915 #endif 916 return(eval); 917 } /* loop through the sops */ 918 } /* if (do_undos) */ 919 920 /* We're definitely done - set the sempid's */ 921 for (i = 0; i < nsops; i++) { 922 sopptr = &sops[i]; 923 semptr = &semaptr->sem_base[sopptr->sem_num]; 924 semptr->sempid = p->p_pid; 925 } 926 927 /* Do a wakeup if any semaphore was up'd. */ 928 if (do_wakeup) { 929 #ifdef SEM_DEBUG 930 printf("semop: doing wakeup\n"); 931 #endif 932 wakeup((caddr_t)semaptr); 933 #ifdef SEM_DEBUG 934 printf("semop: back from wakeup\n"); 935 #endif 936 } 937 #ifdef SEM_DEBUG 938 printf("semop: done\n"); 939 #endif 940 p->p_retval[0] = 0; 941 return(0); 942 } 943 944 /* 945 * Go through the undo structures for this process and apply the adjustments to 946 * semaphores. 947 */ 948 void 949 semexit(p) 950 struct proc *p; 951 { 952 register struct sem_undo *suptr; 953 register struct sem_undo **supptr; 954 int did_something; 955 956 did_something = 0; 957 958 /* 959 * Go through the chain of undo vectors looking for one 960 * associated with this process. 961 */ 962 963 for (supptr = &semu_list; (suptr = *supptr) != NULL; 964 supptr = &suptr->un_next) { 965 if (suptr->un_proc == p) 966 break; 967 } 968 969 if (suptr == NULL) 970 return; 971 972 #ifdef SEM_DEBUG 973 printf("proc @%08x has undo structure with %d entries\n", p, 974 suptr->un_cnt); 975 #endif 976 977 /* 978 * If there are any active undo elements then process them. 979 */ 980 if (suptr->un_cnt > 0) { 981 int ix; 982 983 for (ix = 0; ix < suptr->un_cnt; ix++) { 984 int semid = suptr->un_ent[ix].un_id; 985 int semnum = suptr->un_ent[ix].un_num; 986 int adjval = suptr->un_ent[ix].un_adjval; 987 struct semid_ds *semaptr; 988 989 semaptr = &sema[semid]; 990 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 991 panic("semexit - semid not allocated"); 992 if (semnum >= semaptr->sem_nsems) 993 panic("semexit - semnum out of range"); 994 995 #ifdef SEM_DEBUG 996 printf("semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n", 997 suptr->un_proc, suptr->un_ent[ix].un_id, 998 suptr->un_ent[ix].un_num, 999 suptr->un_ent[ix].un_adjval, 1000 semaptr->sem_base[semnum].semval); 1001 #endif 1002 1003 if (adjval < 0) { 1004 if (semaptr->sem_base[semnum].semval < -adjval) 1005 semaptr->sem_base[semnum].semval = 0; 1006 else 1007 semaptr->sem_base[semnum].semval += 1008 adjval; 1009 } else 1010 semaptr->sem_base[semnum].semval += adjval; 1011 1012 wakeup((caddr_t)semaptr); 1013 #ifdef SEM_DEBUG 1014 printf("semexit: back from wakeup\n"); 1015 #endif 1016 } 1017 } 1018 1019 /* 1020 * Deallocate the undo vector. 1021 */ 1022 #ifdef SEM_DEBUG 1023 printf("removing vector\n"); 1024 #endif 1025 suptr->un_proc = NULL; 1026 *supptr = suptr->un_next; 1027 } 1028