1 /* $FreeBSD: src/sys/kern/sysv_sem.c,v 1.69 2004/03/17 09:37:13 cperciva Exp $ */ 2 /* $DragonFly: src/sys/kern/sysv_sem.c,v 1.14 2004/05/26 14:12:34 hmp 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 (void *); 28 29 #ifndef _SYS_SYSPROTO_H_ 30 struct __semctl_args; 31 int __semctl (struct proc *p, struct __semctl_args *uap); 32 struct semget_args; 33 int semget (struct proc *p, struct semget_args *uap); 34 struct semop_args; 35 int semop (struct proc *p, struct semop_args *uap); 36 #endif 37 38 static struct sem_undo *semu_alloc (struct proc *p); 39 static int semundo_adjust (struct proc *p, struct sem_undo **supptr, 40 int semid, int semnum, int adjval); 41 static void semundo_clear (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_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, ""); 149 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0, ""); 150 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0, ""); 151 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0, ""); 152 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, ""); 153 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0, ""); 154 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0, ""); 155 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0, ""); 156 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, ""); 157 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, ""); 158 159 #if 0 160 RO seminfo.semmap /* SEMMAP unused */ 161 RO seminfo.semmni 162 RO seminfo.semmns 163 RO seminfo.semmnu /* undo entries per system */ 164 RW seminfo.semmsl 165 RO seminfo.semopm /* SEMOPM unused */ 166 RO seminfo.semume 167 RO seminfo.semusz /* param - derived from SEMUME for per-proc sizeof */ 168 RO seminfo.semvmx /* SEMVMX unused - user param */ 169 RO seminfo.semaem /* SEMAEM unused - user param */ 170 #endif 171 172 static void 173 seminit(dummy) 174 void *dummy; 175 { 176 int i; 177 178 sem = malloc(sizeof(struct sem) * seminfo.semmns, M_SEM, M_WAITOK); 179 if (sem == NULL) 180 panic("sem is NULL"); 181 sema = malloc(sizeof(struct semid_ds) * seminfo.semmni, M_SEM, M_WAITOK); 182 if (sema == NULL) 183 panic("sema is NULL"); 184 semu = malloc(seminfo.semmnu * seminfo.semusz, M_SEM, M_WAITOK); 185 if (semu == NULL) 186 panic("semu is NULL"); 187 188 for (i = 0; i < seminfo.semmni; i++) { 189 sema[i].sem_base = 0; 190 sema[i].sem_perm.mode = 0; 191 } 192 for (i = 0; i < seminfo.semmnu; i++) { 193 struct sem_undo *suptr = SEMU(i); 194 suptr->un_proc = NULL; 195 } 196 semu_list = NULL; 197 } 198 SYSINIT(sysv_sem, SI_SUB_SYSV_SEM, SI_ORDER_FIRST, seminit, NULL) 199 200 /* 201 * Entry point for all SEM calls 202 * 203 * semsys_args(int which, a2, a3, ...) (VARARGS) 204 */ 205 int 206 semsys(struct semsys_args *uap) 207 { 208 struct proc *p = curproc; 209 unsigned int which = (unsigned int)uap->which; 210 211 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL) 212 return (ENOSYS); 213 214 if (which >= sizeof(semcalls)/sizeof(semcalls[0])) 215 return (EINVAL); 216 bcopy(&uap->a2, &uap->which, 217 sizeof(struct semsys_args) - offsetof(struct semsys_args, a2)); 218 return ((*semcalls[which])(uap)); 219 } 220 221 /* 222 * Allocate a new sem_undo structure for a process 223 * (returns ptr to structure or NULL if no more room) 224 */ 225 226 static struct sem_undo * 227 semu_alloc(p) 228 struct proc *p; 229 { 230 int i; 231 struct sem_undo *suptr; 232 struct sem_undo **supptr; 233 int attempt; 234 235 /* 236 * Try twice to allocate something. 237 * (we'll purge any empty structures after the first pass so 238 * two passes are always enough) 239 */ 240 241 for (attempt = 0; attempt < 2; attempt++) { 242 /* 243 * Look for a free structure. 244 * Fill it in and return it if we find one. 245 */ 246 247 for (i = 0; i < seminfo.semmnu; i++) { 248 suptr = SEMU(i); 249 if (suptr->un_proc == NULL) { 250 suptr->un_next = semu_list; 251 semu_list = suptr; 252 suptr->un_cnt = 0; 253 suptr->un_proc = p; 254 return(suptr); 255 } 256 } 257 258 /* 259 * We didn't find a free one, if this is the first attempt 260 * then try to free some structures. 261 */ 262 263 if (attempt == 0) { 264 /* All the structures are in use - try to free some */ 265 int did_something = 0; 266 267 supptr = &semu_list; 268 while ((suptr = *supptr) != NULL) { 269 if (suptr->un_cnt == 0) { 270 suptr->un_proc = NULL; 271 *supptr = suptr->un_next; 272 did_something = 1; 273 } else 274 supptr = &(suptr->un_next); 275 } 276 277 /* If we didn't free anything then just give-up */ 278 if (!did_something) 279 return(NULL); 280 } else { 281 /* 282 * The second pass failed even though we freed 283 * something after the first pass! 284 * This is IMPOSSIBLE! 285 */ 286 panic("semu_alloc - second attempt failed"); 287 } 288 } 289 return (NULL); 290 } 291 292 /* 293 * Adjust a particular entry for a particular proc 294 */ 295 296 static int 297 semundo_adjust(p, supptr, semid, semnum, adjval) 298 struct proc *p; 299 struct sem_undo **supptr; 300 int semid, semnum; 301 int adjval; 302 { 303 struct sem_undo *suptr; 304 struct undo *sunptr; 305 int i; 306 307 /* Look for and remember the sem_undo if the caller doesn't provide 308 it */ 309 310 suptr = *supptr; 311 if (suptr == NULL) { 312 for (suptr = semu_list; suptr != NULL; 313 suptr = suptr->un_next) { 314 if (suptr->un_proc == p) { 315 *supptr = suptr; 316 break; 317 } 318 } 319 if (suptr == NULL) { 320 if (adjval == 0) 321 return(0); 322 suptr = semu_alloc(p); 323 if (suptr == NULL) 324 return(ENOSPC); 325 *supptr = suptr; 326 } 327 } 328 329 /* 330 * Look for the requested entry and adjust it (delete if adjval becomes 331 * 0). 332 */ 333 sunptr = &suptr->un_ent[0]; 334 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 335 if (sunptr->un_id != semid || sunptr->un_num != semnum) 336 continue; 337 if (adjval == 0) 338 sunptr->un_adjval = 0; 339 else 340 sunptr->un_adjval += adjval; 341 if (sunptr->un_adjval == 0) { 342 suptr->un_cnt--; 343 if (i < suptr->un_cnt) 344 suptr->un_ent[i] = 345 suptr->un_ent[suptr->un_cnt]; 346 } 347 return(0); 348 } 349 350 /* Didn't find the right entry - create it */ 351 if (adjval == 0) 352 return(0); 353 if (suptr->un_cnt != seminfo.semume) { 354 sunptr = &suptr->un_ent[suptr->un_cnt]; 355 suptr->un_cnt++; 356 sunptr->un_adjval = adjval; 357 sunptr->un_id = semid; sunptr->un_num = semnum; 358 } else 359 return(EINVAL); 360 return(0); 361 } 362 363 static void 364 semundo_clear(semid, semnum) 365 int semid, semnum; 366 { 367 struct sem_undo *suptr; 368 369 for (suptr = semu_list; suptr != NULL; suptr = suptr->un_next) { 370 struct undo *sunptr = &suptr->un_ent[0]; 371 int i = 0; 372 373 while (i < suptr->un_cnt) { 374 if (sunptr->un_id == semid) { 375 if (semnum == -1 || sunptr->un_num == semnum) { 376 suptr->un_cnt--; 377 if (i < suptr->un_cnt) { 378 suptr->un_ent[i] = 379 suptr->un_ent[suptr->un_cnt]; 380 continue; 381 } 382 } 383 if (semnum != -1) 384 break; 385 } 386 i++, sunptr++; 387 } 388 } 389 } 390 391 /* 392 * Note that the user-mode half of this passes a union, not a pointer 393 */ 394 395 int 396 __semctl(struct __semctl_args *uap) 397 { 398 struct proc *p = curproc; 399 int semid = uap->semid; 400 int semnum = uap->semnum; 401 int cmd = uap->cmd; 402 union semun *arg = uap->arg; 403 union semun real_arg; 404 struct ucred *cred = p->p_ucred; 405 int i, rval, eval; 406 struct semid_ds sbuf; 407 struct semid_ds *semaptr; 408 409 #ifdef SEM_DEBUG 410 printf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg); 411 #endif 412 413 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL) 414 return (ENOSYS); 415 416 semid = IPCID_TO_IX(semid); 417 if (semid < 0 || semid >= seminfo.semmni) 418 return(EINVAL); 419 420 semaptr = &sema[semid]; 421 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 422 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 423 return(EINVAL); 424 425 eval = 0; 426 rval = 0; 427 428 switch (cmd) { 429 case IPC_RMID: 430 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M))) 431 return(eval); 432 semaptr->sem_perm.cuid = cred->cr_uid; 433 semaptr->sem_perm.uid = cred->cr_uid; 434 semtot -= semaptr->sem_nsems; 435 for (i = semaptr->sem_base - sem; i < semtot; i++) 436 sem[i] = sem[i + semaptr->sem_nsems]; 437 for (i = 0; i < seminfo.semmni; i++) { 438 if ((sema[i].sem_perm.mode & SEM_ALLOC) && 439 sema[i].sem_base > semaptr->sem_base) 440 sema[i].sem_base -= semaptr->sem_nsems; 441 } 442 semaptr->sem_perm.mode = 0; 443 semundo_clear(semid, -1); 444 wakeup((caddr_t)semaptr); 445 break; 446 447 case IPC_SET: 448 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_M))) 449 return(eval); 450 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 451 return(eval); 452 if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf, 453 sizeof(sbuf))) != 0) 454 return(eval); 455 semaptr->sem_perm.uid = sbuf.sem_perm.uid; 456 semaptr->sem_perm.gid = sbuf.sem_perm.gid; 457 semaptr->sem_perm.mode = (semaptr->sem_perm.mode & ~0777) | 458 (sbuf.sem_perm.mode & 0777); 459 semaptr->sem_ctime = time_second; 460 break; 461 462 case IPC_STAT: 463 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 464 return(eval); 465 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 466 return(eval); 467 eval = copyout((caddr_t)semaptr, real_arg.buf, 468 sizeof(struct semid_ds)); 469 break; 470 471 case GETNCNT: 472 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 473 return(eval); 474 if (semnum < 0 || semnum >= semaptr->sem_nsems) 475 return(EINVAL); 476 rval = semaptr->sem_base[semnum].semncnt; 477 break; 478 479 case GETPID: 480 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 481 return(eval); 482 if (semnum < 0 || semnum >= semaptr->sem_nsems) 483 return(EINVAL); 484 rval = semaptr->sem_base[semnum].sempid; 485 break; 486 487 case GETVAL: 488 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 489 return(eval); 490 if (semnum < 0 || semnum >= semaptr->sem_nsems) 491 return(EINVAL); 492 rval = semaptr->sem_base[semnum].semval; 493 break; 494 495 case GETALL: 496 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 497 return(eval); 498 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 499 return(eval); 500 for (i = 0; i < semaptr->sem_nsems; i++) { 501 eval = copyout((caddr_t)&semaptr->sem_base[i].semval, 502 &real_arg.array[i], sizeof(real_arg.array[0])); 503 if (eval != 0) 504 break; 505 } 506 break; 507 508 case GETZCNT: 509 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_R))) 510 return(eval); 511 if (semnum < 0 || semnum >= semaptr->sem_nsems) 512 return(EINVAL); 513 rval = semaptr->sem_base[semnum].semzcnt; 514 break; 515 516 case SETVAL: 517 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) 518 return(eval); 519 if (semnum < 0 || semnum >= semaptr->sem_nsems) 520 return(EINVAL); 521 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 522 return(eval); 523 semaptr->sem_base[semnum].semval = real_arg.val; 524 semundo_clear(semid, semnum); 525 wakeup((caddr_t)semaptr); 526 break; 527 528 case SETALL: 529 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) 530 return(eval); 531 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 532 return(eval); 533 for (i = 0; i < semaptr->sem_nsems; i++) { 534 eval = copyin(&real_arg.array[i], 535 (caddr_t)&semaptr->sem_base[i].semval, 536 sizeof(real_arg.array[0])); 537 if (eval != 0) 538 break; 539 } 540 semundo_clear(semid, -1); 541 wakeup((caddr_t)semaptr); 542 break; 543 544 default: 545 return(EINVAL); 546 } 547 548 if (eval == 0) 549 uap->sysmsg_result = rval; 550 return(eval); 551 } 552 553 int 554 semget(struct semget_args *uap) 555 { 556 struct proc *p = curproc; 557 int semid, eval; 558 int key = uap->key; 559 int nsems = uap->nsems; 560 int semflg = uap->semflg; 561 struct ucred *cred = p->p_ucred; 562 563 #ifdef SEM_DEBUG 564 printf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg); 565 #endif 566 567 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL) 568 return (ENOSYS); 569 570 if (key != IPC_PRIVATE) { 571 for (semid = 0; semid < seminfo.semmni; semid++) { 572 if ((sema[semid].sem_perm.mode & SEM_ALLOC) && 573 sema[semid].sem_perm.key == key) 574 break; 575 } 576 if (semid < seminfo.semmni) { 577 #ifdef SEM_DEBUG 578 printf("found public key\n"); 579 #endif 580 if ((eval = ipcperm(p, &sema[semid].sem_perm, 581 semflg & 0700))) 582 return(eval); 583 if (nsems > 0 && sema[semid].sem_nsems < nsems) { 584 #ifdef SEM_DEBUG 585 printf("too small\n"); 586 #endif 587 return(EINVAL); 588 } 589 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 590 #ifdef SEM_DEBUG 591 printf("not exclusive\n"); 592 #endif 593 return(EEXIST); 594 } 595 goto found; 596 } 597 } 598 599 #ifdef SEM_DEBUG 600 printf("need to allocate the semid_ds\n"); 601 #endif 602 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 603 if (nsems <= 0 || nsems > seminfo.semmsl) { 604 #ifdef SEM_DEBUG 605 printf("nsems out of range (0<%d<=%d)\n", nsems, 606 seminfo.semmsl); 607 #endif 608 return(EINVAL); 609 } 610 if (nsems > seminfo.semmns - semtot) { 611 #ifdef SEM_DEBUG 612 printf("not enough semaphores left (need %d, got %d)\n", 613 nsems, seminfo.semmns - semtot); 614 #endif 615 return(ENOSPC); 616 } 617 for (semid = 0; semid < seminfo.semmni; semid++) { 618 if ((sema[semid].sem_perm.mode & SEM_ALLOC) == 0) 619 break; 620 } 621 if (semid == seminfo.semmni) { 622 #ifdef SEM_DEBUG 623 printf("no more semid_ds's available\n"); 624 #endif 625 return(ENOSPC); 626 } 627 #ifdef SEM_DEBUG 628 printf("semid %d is available\n", semid); 629 #endif 630 sema[semid].sem_perm.key = key; 631 sema[semid].sem_perm.cuid = cred->cr_uid; 632 sema[semid].sem_perm.uid = cred->cr_uid; 633 sema[semid].sem_perm.cgid = cred->cr_gid; 634 sema[semid].sem_perm.gid = cred->cr_gid; 635 sema[semid].sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 636 sema[semid].sem_perm.seq = 637 (sema[semid].sem_perm.seq + 1) & 0x7fff; 638 sema[semid].sem_nsems = nsems; 639 sema[semid].sem_otime = 0; 640 sema[semid].sem_ctime = time_second; 641 sema[semid].sem_base = &sem[semtot]; 642 semtot += nsems; 643 bzero(sema[semid].sem_base, 644 sizeof(sema[semid].sem_base[0])*nsems); 645 #ifdef SEM_DEBUG 646 printf("sembase = 0x%x, next = 0x%x\n", sema[semid].sem_base, 647 &sem[semtot]); 648 #endif 649 } else { 650 #ifdef SEM_DEBUG 651 printf("didn't find it and wasn't asked to create it\n"); 652 #endif 653 return(ENOENT); 654 } 655 656 found: 657 uap->sysmsg_result = IXSEQ_TO_IPCID(semid, sema[semid].sem_perm); 658 return(0); 659 } 660 661 int 662 semop(struct semop_args *uap) 663 { 664 struct proc *p = curproc; 665 int semid = uap->semid; 666 u_int nsops = uap->nsops; 667 struct sembuf sops[MAX_SOPS]; 668 struct semid_ds *semaptr; 669 struct sembuf *sopptr; 670 struct sem *semptr; 671 struct sem_undo *suptr = NULL; 672 int i, j, eval; 673 int do_wakeup, do_undos; 674 675 #ifdef SEM_DEBUG 676 printf("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops); 677 #endif 678 679 if (!jail_sysvipc_allowed && p->p_ucred->cr_prison != NULL) 680 return (ENOSYS); 681 682 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 683 684 if (semid < 0 || semid >= seminfo.semmni) 685 return(EINVAL); 686 687 semaptr = &sema[semid]; 688 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 689 return(EINVAL); 690 if (semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 691 return(EINVAL); 692 693 if ((eval = ipcperm(p, &semaptr->sem_perm, IPC_W))) { 694 #ifdef SEM_DEBUG 695 printf("eval = %d from ipaccess\n", eval); 696 #endif 697 return(eval); 698 } 699 700 if (nsops > MAX_SOPS) { 701 #ifdef SEM_DEBUG 702 printf("too many sops (max=%d, nsops=%u)\n", MAX_SOPS, nsops); 703 #endif 704 return(E2BIG); 705 } 706 707 if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) { 708 #ifdef SEM_DEBUG 709 printf("eval = %d from copyin(%08x, %08x, %u)\n", eval, 710 uap->sops, &sops, nsops * sizeof(sops[0])); 711 #endif 712 return(eval); 713 } 714 715 /* 716 * Loop trying to satisfy the vector of requests. 717 * If we reach a point where we must wait, any requests already 718 * performed are rolled back and we go to sleep until some other 719 * process wakes us up. At this point, we start all over again. 720 * 721 * This ensures that from the perspective of other tasks, a set 722 * of requests is atomic (never partially satisfied). 723 */ 724 do_undos = 0; 725 726 for (;;) { 727 do_wakeup = 0; 728 729 for (i = 0; i < nsops; i++) { 730 sopptr = &sops[i]; 731 732 if (sopptr->sem_num >= semaptr->sem_nsems) 733 return(EFBIG); 734 735 semptr = &semaptr->sem_base[sopptr->sem_num]; 736 737 #ifdef SEM_DEBUG 738 printf("semop: semaptr=%x, sem_base=%x, semptr=%x, sem[%d]=%d : op=%d, flag=%s\n", 739 semaptr, semaptr->sem_base, semptr, 740 sopptr->sem_num, semptr->semval, sopptr->sem_op, 741 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait"); 742 #endif 743 744 if (sopptr->sem_op < 0) { 745 if (semptr->semval + sopptr->sem_op < 0) { 746 #ifdef SEM_DEBUG 747 printf("semop: can't do it now\n"); 748 #endif 749 break; 750 } else { 751 semptr->semval += sopptr->sem_op; 752 if (semptr->semval == 0 && 753 semptr->semzcnt > 0) 754 do_wakeup = 1; 755 } 756 if (sopptr->sem_flg & SEM_UNDO) 757 do_undos = 1; 758 } else if (sopptr->sem_op == 0) { 759 if (semptr->semval > 0) { 760 #ifdef SEM_DEBUG 761 printf("semop: not zero now\n"); 762 #endif 763 break; 764 } 765 } else { 766 if (semptr->semncnt > 0) 767 do_wakeup = 1; 768 semptr->semval += sopptr->sem_op; 769 if (sopptr->sem_flg & SEM_UNDO) 770 do_undos = 1; 771 } 772 } 773 774 /* 775 * Did we get through the entire vector? 776 */ 777 if (i >= nsops) 778 goto done; 779 780 /* 781 * No ... rollback anything that we've already done 782 */ 783 #ifdef SEM_DEBUG 784 printf("semop: rollback 0 through %d\n", i-1); 785 #endif 786 for (j = 0; j < i; j++) 787 semaptr->sem_base[sops[j].sem_num].semval -= 788 sops[j].sem_op; 789 790 /* 791 * If the request that we couldn't satisfy has the 792 * NOWAIT flag set then return with EAGAIN. 793 */ 794 if (sopptr->sem_flg & IPC_NOWAIT) 795 return(EAGAIN); 796 797 if (sopptr->sem_op == 0) 798 semptr->semzcnt++; 799 else 800 semptr->semncnt++; 801 802 #ifdef SEM_DEBUG 803 printf("semop: good night!\n"); 804 #endif 805 eval = tsleep((caddr_t)semaptr, PCATCH, "semwait", 0); 806 #ifdef SEM_DEBUG 807 printf("semop: good morning (eval=%d)!\n", eval); 808 #endif 809 810 suptr = NULL; /* sem_undo may have been reallocated */ 811 812 /* return code is checked below, after sem[nz]cnt-- */ 813 814 /* 815 * Make sure that the semaphore still exists 816 */ 817 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0 || 818 semaptr->sem_perm.seq != IPCID_TO_SEQ(uap->semid)) 819 return(EIDRM); 820 821 /* 822 * The semaphore is still alive. Readjust the count of 823 * waiting processes. 824 */ 825 if (sopptr->sem_op == 0) 826 semptr->semzcnt--; 827 else 828 semptr->semncnt--; 829 830 /* 831 * Is it really morning, or was our sleep interrupted? 832 * (Delayed check of msleep() return code because we 833 * need to decrement sem[nz]cnt either way.) 834 */ 835 if (eval != 0) 836 return(EINTR); 837 #ifdef SEM_DEBUG 838 printf("semop: good morning!\n"); 839 #endif 840 } 841 842 done: 843 /* 844 * Process any SEM_UNDO requests. 845 */ 846 if (do_undos) { 847 for (i = 0; i < nsops; i++) { 848 /* 849 * We only need to deal with SEM_UNDO's for non-zero 850 * op's. 851 */ 852 int adjval; 853 854 if ((sops[i].sem_flg & SEM_UNDO) == 0) 855 continue; 856 adjval = sops[i].sem_op; 857 if (adjval == 0) 858 continue; 859 eval = semundo_adjust(p, &suptr, semid, 860 sops[i].sem_num, -adjval); 861 if (eval == 0) 862 continue; 863 864 /* 865 * Oh-Oh! We ran out of either sem_undo's or undo's. 866 * Rollback the adjustments to this point and then 867 * rollback the semaphore ups and down so we can return 868 * with an error with all structures restored. We 869 * rollback the undo's in the exact reverse order that 870 * we applied them. This guarantees that we won't run 871 * out of space as we roll things back out. 872 */ 873 for (j = i - 1; j >= 0; j--) { 874 if ((sops[j].sem_flg & SEM_UNDO) == 0) 875 continue; 876 adjval = sops[j].sem_op; 877 if (adjval == 0) 878 continue; 879 if (semundo_adjust(p, &suptr, semid, 880 sops[j].sem_num, adjval) != 0) 881 panic("semop - can't undo undos"); 882 } 883 884 for (j = 0; j < nsops; j++) 885 semaptr->sem_base[sops[j].sem_num].semval -= 886 sops[j].sem_op; 887 888 #ifdef SEM_DEBUG 889 printf("eval = %d from semundo_adjust\n", eval); 890 #endif 891 return(eval); 892 } /* loop through the sops */ 893 } /* if (do_undos) */ 894 895 /* We're definitely done - set the sempid's */ 896 for (i = 0; i < nsops; i++) { 897 sopptr = &sops[i]; 898 semptr = &semaptr->sem_base[sopptr->sem_num]; 899 semptr->sempid = p->p_pid; 900 } 901 902 /* Do a wakeup if any semaphore was up'd. */ 903 if (do_wakeup) { 904 #ifdef SEM_DEBUG 905 printf("semop: doing wakeup\n"); 906 #endif 907 wakeup((caddr_t)semaptr); 908 #ifdef SEM_DEBUG 909 printf("semop: back from wakeup\n"); 910 #endif 911 } 912 #ifdef SEM_DEBUG 913 printf("semop: done\n"); 914 #endif 915 uap->sysmsg_result = 0; 916 return(0); 917 } 918 919 /* 920 * Go through the undo structures for this process and apply the adjustments to 921 * semaphores. 922 */ 923 void 924 semexit(p) 925 struct proc *p; 926 { 927 struct sem_undo *suptr; 928 struct sem_undo **supptr; 929 int did_something; 930 931 did_something = 0; 932 933 /* 934 * Go through the chain of undo vectors looking for one 935 * associated with this process. 936 */ 937 938 for (supptr = &semu_list; (suptr = *supptr) != NULL; 939 supptr = &suptr->un_next) { 940 if (suptr->un_proc == p) 941 break; 942 } 943 944 if (suptr == NULL) 945 return; 946 947 #ifdef SEM_DEBUG 948 printf("proc @%08x has undo structure with %d entries\n", p, 949 suptr->un_cnt); 950 #endif 951 952 /* 953 * If there are any active undo elements then process them. 954 */ 955 if (suptr->un_cnt > 0) { 956 int ix; 957 958 for (ix = 0; ix < suptr->un_cnt; ix++) { 959 int semid = suptr->un_ent[ix].un_id; 960 int semnum = suptr->un_ent[ix].un_num; 961 int adjval = suptr->un_ent[ix].un_adjval; 962 struct semid_ds *semaptr; 963 964 semaptr = &sema[semid]; 965 if ((semaptr->sem_perm.mode & SEM_ALLOC) == 0) 966 panic("semexit - semid not allocated"); 967 if (semnum >= semaptr->sem_nsems) 968 panic("semexit - semnum out of range"); 969 970 #ifdef SEM_DEBUG 971 printf("semexit: %08x id=%d num=%d(adj=%d) ; sem=%d\n", 972 suptr->un_proc, suptr->un_ent[ix].un_id, 973 suptr->un_ent[ix].un_num, 974 suptr->un_ent[ix].un_adjval, 975 semaptr->sem_base[semnum].semval); 976 #endif 977 978 if (adjval < 0) { 979 if (semaptr->sem_base[semnum].semval < -adjval) 980 semaptr->sem_base[semnum].semval = 0; 981 else 982 semaptr->sem_base[semnum].semval += 983 adjval; 984 } else 985 semaptr->sem_base[semnum].semval += adjval; 986 987 wakeup((caddr_t)semaptr); 988 #ifdef SEM_DEBUG 989 printf("semexit: back from wakeup\n"); 990 #endif 991 } 992 } 993 994 /* 995 * Deallocate the undo vector. 996 */ 997 #ifdef SEM_DEBUG 998 printf("removing vector\n"); 999 #endif 1000 suptr->un_proc = NULL; 1001 *supptr = suptr->un_next; 1002 } 1003