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 1.5 2003/07/24 01:41:25 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 * semsys_args(u_int which, a2, a3, ...) (VARARGS) 205 */ 206 int 207 semsys(struct semsys_args *uap) 208 { 209 struct proc *p = curproc; 210 211 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL) 212 return (ENOSYS); 213 214 if (uap->which >= sizeof(semcalls)/sizeof(semcalls[0])) 215 return (EINVAL); 216 return ((*semcalls[uap->which])(&uap->a2)); 217 } 218 219 /* 220 * Allocate a new sem_undo structure for a process 221 * (returns ptr to structure or NULL if no more room) 222 */ 223 224 static struct sem_undo * 225 semu_alloc(p) 226 struct proc *p; 227 { 228 register int i; 229 register struct sem_undo *suptr; 230 register struct sem_undo **supptr; 231 int attempt; 232 233 /* 234 * Try twice to allocate something. 235 * (we'll purge any empty structures after the first pass so 236 * two passes are always enough) 237 */ 238 239 for (attempt = 0; attempt < 2; attempt++) { 240 /* 241 * Look for a free structure. 242 * Fill it in and return it if we find one. 243 */ 244 245 for (i = 0; i < seminfo.semmnu; i++) { 246 suptr = SEMU(i); 247 if (suptr->un_proc == NULL) { 248 suptr->un_next = semu_list; 249 semu_list = suptr; 250 suptr->un_cnt = 0; 251 suptr->un_proc = p; 252 return(suptr); 253 } 254 } 255 256 /* 257 * We didn't find a free one, if this is the first attempt 258 * then try to free some structures. 259 */ 260 261 if (attempt == 0) { 262 /* All the structures are in use - try to free some */ 263 int did_something = 0; 264 265 supptr = &semu_list; 266 while ((suptr = *supptr) != NULL) { 267 if (suptr->un_cnt == 0) { 268 suptr->un_proc = NULL; 269 *supptr = suptr->un_next; 270 did_something = 1; 271 } else 272 supptr = &(suptr->un_next); 273 } 274 275 /* If we didn't free anything then just give-up */ 276 if (!did_something) 277 return(NULL); 278 } else { 279 /* 280 * The second pass failed even though we freed 281 * something after the first pass! 282 * This is IMPOSSIBLE! 283 */ 284 panic("semu_alloc - second attempt failed"); 285 } 286 } 287 return (NULL); 288 } 289 290 /* 291 * Adjust a particular entry for a particular proc 292 */ 293 294 static int 295 semundo_adjust(p, supptr, semid, semnum, adjval) 296 register struct proc *p; 297 struct sem_undo **supptr; 298 int semid, semnum; 299 int adjval; 300 { 301 register struct sem_undo *suptr; 302 register struct undo *sunptr; 303 int i; 304 305 /* Look for and remember the sem_undo if the caller doesn't provide 306 it */ 307 308 suptr = *supptr; 309 if (suptr == NULL) { 310 for (suptr = semu_list; suptr != NULL; 311 suptr = suptr->un_next) { 312 if (suptr->un_proc == p) { 313 *supptr = suptr; 314 break; 315 } 316 } 317 if (suptr == NULL) { 318 if (adjval == 0) 319 return(0); 320 suptr = semu_alloc(p); 321 if (suptr == NULL) 322 return(ENOSPC); 323 *supptr = suptr; 324 } 325 } 326 327 /* 328 * Look for the requested entry and adjust it (delete if adjval becomes 329 * 0). 330 */ 331 sunptr = &suptr->un_ent[0]; 332 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 333 if (sunptr->un_id != semid || sunptr->un_num != semnum) 334 continue; 335 if (adjval == 0) 336 sunptr->un_adjval = 0; 337 else 338 sunptr->un_adjval += adjval; 339 if (sunptr->un_adjval == 0) { 340 suptr->un_cnt--; 341 if (i < suptr->un_cnt) 342 suptr->un_ent[i] = 343 suptr->un_ent[suptr->un_cnt]; 344 } 345 return(0); 346 } 347 348 /* Didn't find the right entry - create it */ 349 if (adjval == 0) 350 return(0); 351 if (suptr->un_cnt != seminfo.semume) { 352 sunptr = &suptr->un_ent[suptr->un_cnt]; 353 suptr->un_cnt++; 354 sunptr->un_adjval = adjval; 355 sunptr->un_id = semid; sunptr->un_num = semnum; 356 } else 357 return(EINVAL); 358 return(0); 359 } 360 361 static void 362 semundo_clear(semid, semnum) 363 int semid, semnum; 364 { 365 register struct sem_undo *suptr; 366 367 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { 368 register struct undo *sunptr = &suptr->un_ent[0]; 369 register int i = 0; 370 371 while (i < suptr->un_cnt) { 372 if (sunptr->un_id == semid) { 373 if (semnum == -1 || sunptr->un_num == semnum) { 374 suptr->un_cnt--; 375 if (i < suptr->un_cnt) { 376 suptr->un_ent[i] = 377 suptr->un_ent[suptr->un_cnt]; 378 continue; 379 } 380 } 381 if (semnum != -1) 382 break; 383 } 384 i++, sunptr++; 385 } 386 } 387 } 388 389 /* 390 * Note that the user-mode half of this passes a union, not a pointer 391 */ 392 393 int 394 __semctl(struct __semctl_args *uap) 395 { 396 struct proc *p = curproc; 397 int semid = uap->semid; 398 int semnum = uap->semnum; 399 int cmd = uap->cmd; 400 union semun *arg = uap->arg; 401 union semun real_arg; 402 struct ucred *cred = p->p_ucred; 403 int i, rval, eval; 404 struct semid_ds sbuf; 405 register struct semid_ds *semaptr; 406 407 #ifdef SEM_DEBUG 408 printf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg); 409 #endif 410 411 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL) 412 return (ENOSYS); 413 414 semid = IPCID_TO_IX(semid); 415 if (semid < 0 || semid >= seminfo.semmni) 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 int 552 semget(struct semget_args *uap) 553 { 554 struct proc *p = curproc; 555 int semid, eval; 556 int key = uap->key; 557 int nsems = uap->nsems; 558 int semflg = uap->semflg; 559 struct ucred *cred = p->p_ucred; 560 561 #ifdef SEM_DEBUG 562 printf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg); 563 #endif 564 565 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL) 566 return (ENOSYS); 567 568 if (key != IPC_PRIVATE) { 569 for (semid = 0; semid < seminfo.semmni; semid++) { 570 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 571 sema[semid].sem_perm.key == key) 572 break; 573 } 574 if (semid < seminfo.semmni) { 575 #ifdef SEM_DEBUG 576 printf("found public key\n"); 577 #endif 578 if ((eval = ipcperm(p, &sema[semid].sem_perm, 579 semflg & 0700))) 580 return(eval); 581 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 582 #ifdef SEM_DEBUG 583 printf("too small\n"); 584 #endif 585 return(EINVAL); 586 } 587 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 588 #ifdef SEM_DEBUG 589 printf("not exclusive\n"); 590 #endif 591 return(EEXIST); 592 } 593 goto found; 594 } 595 } 596 597 #ifdef SEM_DEBUG 598 printf("need to allocate the semid_ds\n"); 599 #endif 600 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 601 if (nsems <= 0 || nsems > seminfo.semmsl) { 602 #ifdef SEM_DEBUG 603 printf("nsems out of range (0<%d<=%d)\n", nsems, 604 seminfo.semmsl); 605 #endif 606 return(EINVAL); 607 } 608 if (nsems > seminfo.semmns - semtot) { 609 #ifdef SEM_DEBUG 610 printf("not enough semaphores left (need %d, got %d)\n", 611 nsems, seminfo.semmns - semtot); 612 #endif 613 return(ENOSPC); 614 } 615 for (semid = 0; semid < seminfo.semmni; semid++) { 616 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 617 break; 618 } 619 if (semid == seminfo.semmni) { 620 #ifdef SEM_DEBUG 621 printf("no more semid_ds's available\n"); 622 #endif 623 return(ENOSPC); 624 } 625 #ifdef SEM_DEBUG 626 printf("semid %d is available\n", semid); 627 #endif 628 sema[semid].sem_perm.key = key; 629 sema[semid].sem_perm.cuid = cred->cr_uid; 630 sema[semid].sem_perm.uid = cred->cr_uid; 631 sema[semid].sem_perm.cgid = cred->cr_gid; 632 sema[semid].sem_perm.gid = cred->cr_gid; 633 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 634 sema[semid].sem_perm.seq = 635 (sema[semid].sem_perm.seq + 1) & 0x7fff; 636 sema[semid].sem_nsems = nsems; 637 sema[semid].sem_otime = 0; 638 sema[semid].sem_ctime = time_second; 639 sema[semid].sem_base = &sem[semtot]; 640 semtot += nsems; 641 bzero(sema[semid].sem_base, 642 sizeof(sema[semid].sem_base[0])*nsems); 643 #ifdef SEM_DEBUG 644 printf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base, 645 &sem[semtot]); 646 #endif 647 } else { 648 #ifdef SEM_DEBUG 649 printf("didn't find it and wasn't asked to create it\n"); 650 #endif 651 return(ENOENT); 652 } 653 654 found: 655 p->p_retval[0] = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 656 return(0); 657 } 658 659 int 660 semop(struct semop_args *uap) 661 { 662 struct proc *p = curproc; 663 int semid = uap->semid; 664 u_int nsops = uap->nsops; 665 struct sembuf sops[MAX_SOPS]; 666 register struct semid_ds *semaptr; 667 register struct sembuf *sopptr; 668 register struct sem *semptr; 669 struct sem_undo *suptr = NULL; 670 int i, j, eval; 671 int do_wakeup, do_undos; 672 673 #ifdef SEM_DEBUG 674 printf("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops); 675 #endif 676 677 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL) 678 return (ENOSYS); 679 680 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 681 682 if (semid < 0 || semid >= seminfo.semmni) 683 return(EINVAL); 684 685 semaptr = &sema[semid]; 686 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 687 return(EINVAL); 688 if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 689 return(EINVAL); 690 691 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) { 692 #ifdef SEM_DEBUG 693 printf("eval = %d from ipaccess\n", eval); 694 #endif 695 return(eval); 696 } 697 698 if (nsops > MAX_SOPS) { 699 #ifdef SEM_DEBUG 700 printf("too many sops (max=%d, nsops=%u)\n", MAX_SOPS, nsops); 701 #endif 702 return(E2BIG); 703 } 704 705 if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) { 706 #ifdef SEM_DEBUG 707 printf("eval = %d from copyin(%08x, %08x, %u)\n", eval, 708 uap->sops, &sops, nsops * sizeof(sops[0])); 709 #endif 710 return(eval); 711 } 712 713 /* 714 * Loop trying to satisfy the vector of requests. 715 * If we reach a point where we must wait, any requests already 716 * performed are rolled back and we go to sleep until some other 717 * process wakes us up. At this point, we start all over again. 718 * 719 * This ensures that from the perspective of other tasks, a set 720 * of requests is atomic (never partially satisfied). 721 */ 722 do_undos = 0; 723 724 for (;;) { 725 do_wakeup = 0; 726 727 for (i = 0; i < nsops; i++) { 728 sopptr = &sops[i]; 729 730 if (sopptr->sem_num >= semaptr->sem_nsems) 731 return(EFBIG); 732 733 semptr = &semaptr->sem_base[sopptr->sem_num]; 734 735 #ifdef SEM_DEBUG 736 printf("semop: semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n", 737 semaptr, semaptr->sem_base, semptr, 738 sopptr->sem_num, semptr->semval, sopptr->sem_op, 739 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait"); 740 #endif 741 742 if (sopptr->sem_op < 0) { 743 if (semptr->semval + sopptr->sem_op < 0) { 744 #ifdef SEM_DEBUG 745 printf("semop: can't do it now\n"); 746 #endif 747 break; 748 } else { 749 semptr->semval += sopptr->sem_op; 750 if (semptr->semval == 0 && 751 semptr->semzcnt > 0) 752 do_wakeup = 1; 753 } 754 if (sopptr->sem_flg & SEM_UNDO) 755 do_undos = 1; 756 } else if (sopptr->sem_op == 0) { 757 if (semptr->semval > 0) { 758 #ifdef SEM_DEBUG 759 printf("semop: not zero now\n"); 760 #endif 761 break; 762 } 763 } else { 764 if (semptr->semncnt > 0) 765 do_wakeup = 1; 766 semptr->semval += sopptr->sem_op; 767 if (sopptr->sem_flg & SEM_UNDO) 768 do_undos = 1; 769 } 770 } 771 772 /* 773 * Did we get through the entire vector? 774 */ 775 if (i >= nsops) 776 goto done; 777 778 /* 779 * No ... rollback anything that we've already done 780 */ 781 #ifdef SEM_DEBUG 782 printf("semop: rollback 0 through %d\n", i-1); 783 #endif 784 for (j = 0; j < i; j++) 785 semaptr->sem_base[sops[j].sem_num].semval -= 786 sops[j].sem_op; 787 788 /* 789 * If the request that we couldn't satisfy has the 790 * NOWAIT flag set then return with EAGAIN. 791 */ 792 if (sopptr->sem_flg & IPC_NOWAIT) 793 return(EAGAIN); 794 795 if (sopptr->sem_op == 0) 796 semptr->semzcnt++; 797 else 798 semptr->semncnt++; 799 800 #ifdef SEM_DEBUG 801 printf("semop: good night!\n"); 802 #endif 803 eval = tsleep((caddr_t)semaptr, PCATCH, "semwait", 0); 804 #ifdef SEM_DEBUG 805 printf("semop: good morning (eval=%d)!\n", eval); 806 #endif 807 808 suptr = NULL; /* sem_undo may have been reallocated */ 809 810 if (eval != 0) 811 return(EINTR); 812 #ifdef SEM_DEBUG 813 printf("semop: good morning!\n"); 814 #endif 815 816 /* 817 * Make sure that the semaphore still exists 818 */ 819 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 820 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 821 return(EIDRM); 822 823 /* 824 * The semaphore is still alive. Readjust the count of 825 * waiting processes. 826 */ 827 if (sopptr->sem_op == 0) 828 semptr->semzcnt--; 829 else 830 semptr->semncnt--; 831 } 832 833 done: 834 /* 835 * Process any SEM_UNDO requests. 836 */ 837 if (do_undos) { 838 for (i = 0; i < nsops; i++) { 839 /* 840 * We only need to deal with SEM_UNDO's for non-zero 841 * op's. 842 */ 843 int adjval; 844 845 if ((sops[i].sem_flg & SEM_UNDO) == 0) 846 continue; 847 adjval = sops[i].sem_op; 848 if (adjval == 0) 849 continue; 850 eval = semundo_adjust(p, &suptr, semid, 851 sops[i].sem_num, -adjval); 852 if (eval == 0) 853 continue; 854 855 /* 856 * Oh-Oh! We ran out of either sem_undo's or undo's. 857 * Rollback the adjustments to this point and then 858 * rollback the semaphore ups and down so we can return 859 * with an error with all structures restored. We 860 * rollback the undo's in the exact reverse order that 861 * we applied them. This guarantees that we won't run 862 * out of space as we roll things back out. 863 */ 864 for (j = i - 1; j >= 0; j--) { 865 if ((sops[j].sem_flg & SEM_UNDO) == 0) 866 continue; 867 adjval = sops[j].sem_op; 868 if (adjval == 0) 869 continue; 870 if (semundo_adjust(p, &suptr, semid, 871 sops[j].sem_num, adjval) != 0) 872 panic("semop - can't undo undos"); 873 } 874 875 for (j = 0; j < nsops; j++) 876 semaptr->sem_base[sops[j].sem_num].semval -= 877 sops[j].sem_op; 878 879 #ifdef SEM_DEBUG 880 printf("eval = %d from semundo_adjust\n", eval); 881 #endif 882 return(eval); 883 } /* loop through the sops */ 884 } /* if (do_undos) */ 885 886 /* We're definitely done - set the sempid's */ 887 for (i = 0; i < nsops; i++) { 888 sopptr = &sops[i]; 889 semptr = &semaptr->sem_base[sopptr->sem_num]; 890 semptr->sempid = p->p_pid; 891 } 892 893 /* Do a wakeup if any semaphore was up'd. */ 894 if (do_wakeup) { 895 #ifdef SEM_DEBUG 896 printf("semop: doing wakeup\n"); 897 #endif 898 wakeup((caddr_t)semaptr); 899 #ifdef SEM_DEBUG 900 printf("semop: back from wakeup\n"); 901 #endif 902 } 903 #ifdef SEM_DEBUG 904 printf("semop: done\n"); 905 #endif 906 p->p_retval[0] = 0; 907 return(0); 908 } 909 910 /* 911 * Go through the undo structures for this process and apply the adjustments to 912 * semaphores. 913 */ 914 void 915 semexit(p) 916 struct proc *p; 917 { 918 register struct sem_undo *suptr; 919 register struct sem_undo **supptr; 920 int did_something; 921 922 did_something = 0; 923 924 /* 925 * Go through the chain of undo vectors looking for one 926 * associated with this process. 927 */ 928 929 for (supptr = &semu_list; (suptr = *supptr) != NULL; 930 supptr = &suptr->un_next) { 931 if (suptr->un_proc == p) 932 break; 933 } 934 935 if (suptr == NULL) 936 return; 937 938 #ifdef SEM_DEBUG 939 printf("proc @%08x has undo structure with %d entries\n", p, 940 suptr->un_cnt); 941 #endif 942 943 /* 944 * If there are any active undo elements then process them. 945 */ 946 if (suptr->un_cnt > 0) { 947 int ix; 948 949 for (ix = 0; ix < suptr->un_cnt; ix++) { 950 int semid = suptr->un_ent[ix].un_id; 951 int semnum = suptr->un_ent[ix].un_num; 952 int adjval = suptr->un_ent[ix].un_adjval; 953 struct semid_ds *semaptr; 954 955 semaptr = &sema[semid]; 956 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 957 panic("semexit - semid not allocated"); 958 if (semnum >= semaptr->sem_nsems) 959 panic("semexit - semnum out of range"); 960 961 #ifdef SEM_DEBUG 962 printf("semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n", 963 suptr->un_proc, suptr->un_ent[ix].un_id, 964 suptr->un_ent[ix].un_num, 965 suptr->un_ent[ix].un_adjval, 966 semaptr->sem_base[semnum].semval); 967 #endif 968 969 if (adjval < 0) { 970 if (semaptr->sem_base[semnum].semval < -adjval) 971 semaptr->sem_base[semnum].semval = 0; 972 else 973 semaptr->sem_base[semnum].semval += 974 adjval; 975 } else 976 semaptr->sem_base[semnum].semval += adjval; 977 978 wakeup((caddr_t)semaptr); 979 #ifdef SEM_DEBUG 980 printf("semexit: back from wakeup\n"); 981 #endif 982 } 983 } 984 985 /* 986 * Deallocate the undo vector. 987 */ 988 #ifdef SEM_DEBUG 989 printf("removing vector\n"); 990 #endif 991 suptr->un_proc = NULL; 992 *supptr = suptr->un_next; 993 } 994