1 /* $FreeBSD: src/sys/kern/sysv_sem.c,v 1.69 2004/03/17 09:37:13 cperciva Exp $ */ 2 3 /* 4 * Implementation of SVID semaphores 5 * 6 * Author: Daniel Boulet 7 * 8 * This software is provided ``AS IS'' without any warranties of any kind. 9 */ 10 11 #include "opt_sysvipc.h" 12 13 #include <sys/param.h> 14 #include <sys/systm.h> 15 #include <sys/sysproto.h> 16 #include <sys/kernel.h> 17 #include <sys/proc.h> 18 #include <sys/sem.h> 19 #include <sys/sysent.h> 20 #include <sys/sysctl.h> 21 #include <sys/malloc.h> 22 #include <sys/jail.h> 23 #include <sys/thread.h> 24 25 #include <sys/thread2.h> 26 27 static MALLOC_DEFINE(M_SEM, "sem", "SVID compatible semaphores"); 28 29 static void seminit (void *); 30 31 static struct sem_undo *semu_alloc (struct proc *p); 32 static int semundo_adjust (struct proc *p, int semid, int semnum, int adjval); 33 static void semundo_clear (int semid, int semnum); 34 35 static struct lwkt_token semu_token = LWKT_TOKEN_INITIALIZER(semu_token); 36 static int semtot = 0; 37 static struct semid_pool *sema; /* semaphore id pool */ 38 static TAILQ_HEAD(, sem_undo) semu_list = TAILQ_HEAD_INITIALIZER(semu_list); 39 static struct lock sema_lk; 40 41 struct sem { 42 u_short semval; /* semaphore value */ 43 pid_t sempid; /* pid of last operation */ 44 u_short semncnt; /* # awaiting semval > cval */ 45 u_short semzcnt; /* # awaiting semval = 0 */ 46 }; 47 48 /* 49 * Undo structure (one per process) 50 */ 51 struct sem_undo { 52 TAILQ_ENTRY(sem_undo) un_entry; /* linked list for semundo_clear() */ 53 struct proc *un_proc; /* owner of this structure */ 54 int un_refs; /* prevent unlink/kfree */ 55 short un_cnt; /* # of active entries */ 56 short un_unused; 57 struct undo { 58 short un_adjval; /* adjust on exit values */ 59 short un_num; /* semaphore # */ 60 int un_id; /* semid */ 61 } un_ent[1]; /* undo entries */ 62 }; 63 64 /* 65 * Configuration parameters 66 */ 67 #ifndef SEMMNI 68 #define SEMMNI 1024 /* # of semaphore identifiers */ 69 #endif 70 #ifndef SEMMNS 71 #define SEMMNS 32767 /* # of semaphores in system */ 72 #endif 73 #ifndef SEMUME 74 #define SEMUME 25 /* max # of undo entries per process */ 75 #endif 76 #ifndef SEMMNU 77 #define SEMMNU 1024 /* # of undo structures in system */ 78 /* NO LONGER USED */ 79 #endif 80 81 /* shouldn't need tuning */ 82 #ifndef SEMMAP 83 #define SEMMAP 128 /* # of entries in semaphore map */ 84 #endif 85 #ifndef SEMMSL 86 #define SEMMSL SEMMNS /* max # of semaphores per id */ 87 #endif 88 #ifndef SEMOPM 89 #define SEMOPM 100 /* max # of operations per semop call */ 90 #endif 91 92 #define SEMVMX 32767 /* semaphore maximum value */ 93 #define SEMAEM 16384 /* adjust on exit max value */ 94 95 /* 96 * Due to the way semaphore memory is allocated, we have to ensure that 97 * SEMUSZ is properly aligned. 98 */ 99 100 #define SEM_ALIGN(bytes) roundup2(bytes, sizeof(long)) 101 102 /* actual size of an undo structure */ 103 #define SEMUSZ(nent) SEM_ALIGN(offsetof(struct sem_undo, un_ent[nent])) 104 105 /* 106 * semaphore info struct 107 */ 108 struct seminfo seminfo = { 109 SEMMAP, /* # of entries in semaphore map */ 110 SEMMNI, /* # of semaphore identifiers */ 111 SEMMNS, /* # of semaphores in system */ 112 SEMMNU, /* # of undo structures in system */ 113 SEMMSL, /* max # of semaphores per id */ 114 SEMOPM, /* max # of operations per semop call */ 115 SEMUME, /* max # of undo entries per process */ 116 SEMUSZ(SEMUME), /* size in bytes of undo structure */ 117 SEMVMX, /* semaphore maximum value */ 118 SEMAEM /* adjust on exit max value */ 119 }; 120 121 TUNABLE_INT("kern.ipc.semmap", &seminfo.semmap); 122 TUNABLE_INT("kern.ipc.semmni", &seminfo.semmni); 123 TUNABLE_INT("kern.ipc.semmns", &seminfo.semmns); 124 TUNABLE_INT("kern.ipc.semmnu", &seminfo.semmnu); 125 TUNABLE_INT("kern.ipc.semmsl", &seminfo.semmsl); 126 TUNABLE_INT("kern.ipc.semopm", &seminfo.semopm); 127 TUNABLE_INT("kern.ipc.semume", &seminfo.semume); 128 TUNABLE_INT("kern.ipc.semusz", &seminfo.semusz); 129 TUNABLE_INT("kern.ipc.semvmx", &seminfo.semvmx); 130 TUNABLE_INT("kern.ipc.semaem", &seminfo.semaem); 131 132 SYSCTL_INT(_kern_ipc, OID_AUTO, semmap, CTLFLAG_RW, &seminfo.semmap, 0, 133 "Number of entries in semaphore map"); 134 SYSCTL_INT(_kern_ipc, OID_AUTO, semmni, CTLFLAG_RD, &seminfo.semmni, 0, 135 "Number of semaphore identifiers"); 136 SYSCTL_INT(_kern_ipc, OID_AUTO, semmns, CTLFLAG_RD, &seminfo.semmns, 0, 137 "Total number of semaphores"); 138 SYSCTL_INT(_kern_ipc, OID_AUTO, semmnu, CTLFLAG_RD, &seminfo.semmnu, 0, 139 "Total number of undo structures"); 140 SYSCTL_INT(_kern_ipc, OID_AUTO, semmsl, CTLFLAG_RW, &seminfo.semmsl, 0, 141 "Max number of semaphores per id"); 142 SYSCTL_INT(_kern_ipc, OID_AUTO, semopm, CTLFLAG_RD, &seminfo.semopm, 0, 143 "Max number of operations per semop call"); 144 SYSCTL_INT(_kern_ipc, OID_AUTO, semume, CTLFLAG_RD, &seminfo.semume, 0, 145 "Max number of undo entries per process"); 146 SYSCTL_INT(_kern_ipc, OID_AUTO, semusz, CTLFLAG_RD, &seminfo.semusz, 0, 147 "Size in bytes of undo structure"); 148 SYSCTL_INT(_kern_ipc, OID_AUTO, semvmx, CTLFLAG_RW, &seminfo.semvmx, 0, 149 "Semaphore maximum value"); 150 SYSCTL_INT(_kern_ipc, OID_AUTO, semaem, CTLFLAG_RW, &seminfo.semaem, 0, 151 "Adjust on exit max value"); 152 153 #if 0 154 RO seminfo.semmap /* SEMMAP unused */ 155 RO seminfo.semmni 156 RO seminfo.semmns 157 RO seminfo.semmnu /* undo entries per system */ 158 RW seminfo.semmsl 159 RO seminfo.semopm /* SEMOPM unused */ 160 RO seminfo.semume 161 RO seminfo.semusz /* param - derived from SEMUME for per-proc sizeof */ 162 RO seminfo.semvmx /* SEMVMX unused - user param */ 163 RO seminfo.semaem /* SEMAEM unused - user param */ 164 #endif 165 166 static void 167 seminit(void *dummy) 168 { 169 int i; 170 171 sema = kmalloc(sizeof(struct semid_pool) * seminfo.semmni, 172 M_SEM, M_WAITOK | M_ZERO); 173 174 lockinit(&sema_lk, "semglb", 0, 0); 175 for (i = 0; i < seminfo.semmni; i++) { 176 struct semid_pool *semaptr = &sema[i]; 177 178 lockinit(&semaptr->lk, "semary", 0, 0); 179 semaptr->ds.sem_base = NULL; 180 semaptr->ds.sem_perm.mode = 0; 181 } 182 } 183 SYSINIT(sysv_sem, SI_SUB_SYSV_SEM, SI_ORDER_FIRST, seminit, NULL); 184 185 /* 186 * Allocate a new sem_undo structure for a process 187 * (returns ptr to structure or NULL if no more room) 188 */ 189 static struct sem_undo * 190 semu_alloc(struct proc *p) 191 { 192 struct sem_undo *semu; 193 194 /* 195 * Allocate the semu structure and associate it with the process, 196 * as necessary. 197 */ 198 while ((semu = p->p_sem_undo) == NULL) { 199 semu = kmalloc(SEMUSZ(seminfo.semume), M_SEM, 200 M_WAITOK | M_ZERO); 201 lwkt_gettoken(&semu_token); 202 lwkt_gettoken(&p->p_token); 203 if (p->p_sem_undo == NULL) { 204 p->p_sem_undo = semu; 205 p->p_flags |= P_SYSVSEM; 206 semu->un_proc = p; 207 TAILQ_INSERT_TAIL(&semu_list, semu, un_entry); 208 } else { 209 kfree(semu, M_SEM); 210 } 211 lwkt_reltoken(&p->p_token); 212 lwkt_reltoken(&semu_token); 213 } 214 return(semu); 215 } 216 217 /* 218 * Adjust a particular entry for a particular proc 219 */ 220 static int 221 semundo_adjust(struct proc *p, int semid, int semnum, int adjval) 222 { 223 struct sem_undo *suptr; 224 struct undo *sunptr; 225 int i; 226 int error = 0; 227 228 /* 229 * Look for and remember the sem_undo if the caller doesn't 230 * provide it. 231 */ 232 suptr = semu_alloc(p); 233 lwkt_gettoken(&p->p_token); 234 235 /* 236 * Look for the requested entry and adjust it (delete if adjval becomes 237 * 0). 238 */ 239 sunptr = &suptr->un_ent[0]; 240 for (i = 0; i < suptr->un_cnt; i++, sunptr++) { 241 if (sunptr->un_id != semid || sunptr->un_num != semnum) 242 continue; 243 if (adjval == 0) 244 sunptr->un_adjval = 0; 245 else 246 sunptr->un_adjval += adjval; 247 if (sunptr->un_adjval == 0) { 248 suptr->un_cnt--; 249 if (i < suptr->un_cnt) 250 suptr->un_ent[i] = suptr->un_ent[suptr->un_cnt]; 251 } 252 goto done; 253 } 254 255 /* Didn't find the right entry - create it */ 256 if (adjval == 0) 257 goto done; 258 if (suptr->un_cnt != seminfo.semume) { 259 sunptr = &suptr->un_ent[suptr->un_cnt]; 260 suptr->un_cnt++; 261 sunptr->un_adjval = adjval; 262 sunptr->un_id = semid; 263 sunptr->un_num = semnum; 264 } else { 265 error = EINVAL; 266 } 267 done: 268 lwkt_reltoken(&p->p_token); 269 270 return (error); 271 } 272 273 /* 274 * This is rather expensive 275 */ 276 static void 277 semundo_clear(int semid, int semnum) 278 { 279 struct proc *p; 280 struct sem_undo *suptr; 281 struct sem_undo *sunext; 282 struct undo *sunptr; 283 int i; 284 285 lwkt_gettoken(&semu_token); 286 sunext = TAILQ_FIRST(&semu_list); 287 while ((suptr = sunext) != NULL) { 288 if ((p = suptr->un_proc) == NULL) { 289 suptr = TAILQ_NEXT(suptr, un_entry); 290 continue; 291 } 292 ++suptr->un_refs; 293 PHOLD(p); 294 lwkt_gettoken(&p->p_token); 295 296 sunptr = &suptr->un_ent[0]; 297 i = 0; 298 299 while (i < suptr->un_cnt) { 300 if (sunptr->un_id == semid) { 301 if (semnum == -1 || sunptr->un_num == semnum) { 302 suptr->un_cnt--; 303 if (i < suptr->un_cnt) { 304 suptr->un_ent[i] = 305 suptr->un_ent[suptr->un_cnt]; 306 /* 307 * do not increment i 308 * or sunptr after copydown. 309 */ 310 continue; 311 } 312 } 313 if (semnum != -1) 314 break; 315 } 316 ++i; 317 ++sunptr; 318 } 319 320 lwkt_reltoken(&p->p_token); 321 PRELE(p); 322 323 /* 324 * Handle deletion races 325 */ 326 sunext = TAILQ_NEXT(suptr, un_entry); 327 if (--suptr->un_refs == 0 && suptr->un_proc == NULL) { 328 KKASSERT(suptr->un_cnt == 0); 329 TAILQ_REMOVE(&semu_list, suptr, un_entry); 330 kfree(suptr, M_SEM); 331 } 332 } 333 lwkt_reltoken(&semu_token); 334 } 335 336 /* 337 * Note that the user-mode half of this passes a union, not a pointer 338 * 339 * MPALMOSTSAFE 340 */ 341 int 342 sys___semctl(struct __semctl_args *uap) 343 { 344 struct thread *td = curthread; 345 int semid = uap->semid; 346 int semnum = uap->semnum; 347 int cmd = uap->cmd; 348 union semun *arg = uap->arg; 349 union semun real_arg; 350 struct ucred *cred = td->td_ucred; 351 int i, rval, eval; 352 struct semid_ds sbuf; 353 struct semid_pool *semaptr; 354 struct semid_pool *semakptr; 355 struct sem *semptr; 356 357 #ifdef SEM_DEBUG 358 kprintf("call to semctl(%d, %d, %d, 0x%x)\n", semid, semnum, cmd, arg); 359 #endif 360 361 if (!jail_sysvipc_allowed && cred->cr_prison != NULL) 362 return (ENOSYS); 363 364 switch (cmd) { 365 case SEM_STAT: 366 /* 367 * For this command we assume semid is an array index 368 * rather than an IPC id. 369 */ 370 if (semid < 0 || semid >= seminfo.semmni) { 371 eval = EINVAL; 372 break; 373 } 374 semakptr = &sema[semid]; 375 lockmgr(&semakptr->lk, LK_EXCLUSIVE); 376 if ((semakptr->ds.sem_perm.mode & SEM_ALLOC) == 0) { 377 eval = EINVAL; 378 lockmgr(&semakptr->lk, LK_RELEASE); 379 break; 380 } 381 if ((eval = ipcperm(td->td_proc, &semakptr->ds.sem_perm, IPC_R))) { 382 lockmgr(&semakptr->lk, LK_RELEASE); 383 break; 384 } 385 bcopy(&semakptr->ds, arg->buf, sizeof(struct semid_ds)); 386 rval = IXSEQ_TO_IPCID(semid, semakptr->ds.sem_perm); 387 lockmgr(&semakptr->lk, LK_RELEASE); 388 break; 389 } 390 391 semid = IPCID_TO_IX(semid); 392 if (semid < 0 || semid >= seminfo.semmni) { 393 return(EINVAL); 394 } 395 semaptr = &sema[semid]; 396 lockmgr(&semaptr->lk, LK_EXCLUSIVE); 397 398 if ((semaptr->ds.sem_perm.mode & SEM_ALLOC) == 0 || 399 semaptr->ds.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) { 400 lockmgr(&semaptr->lk, LK_RELEASE); 401 return(EINVAL); 402 } 403 404 eval = 0; 405 rval = 0; 406 407 switch (cmd) { 408 case IPC_RMID: 409 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_M); 410 if (eval != 0) 411 break; 412 semaptr->ds.sem_perm.cuid = cred->cr_uid; 413 semaptr->ds.sem_perm.uid = cred->cr_uid; 414 415 /* 416 * NOTE: Nobody will be waiting on the semaphores since 417 * we have an exclusive lock on semaptr->lk). 418 */ 419 lockmgr(&sema_lk, LK_EXCLUSIVE); 420 semtot -= semaptr->ds.sem_nsems; 421 kfree(semaptr->ds.sem_base, M_SEM); 422 semaptr->ds.sem_base = NULL; 423 semaptr->ds.sem_perm.mode = 0; /* clears SEM_ALLOC */ 424 lockmgr(&sema_lk, LK_RELEASE); 425 426 semundo_clear(semid, -1); 427 break; 428 429 case IPC_SET: 430 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_M); 431 if (eval) 432 break; 433 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 434 break; 435 if ((eval = copyin(real_arg.buf, (caddr_t)&sbuf, 436 sizeof(sbuf))) != 0) { 437 break; 438 } 439 semaptr->ds.sem_perm.uid = sbuf.sem_perm.uid; 440 semaptr->ds.sem_perm.gid = sbuf.sem_perm.gid; 441 semaptr->ds.sem_perm.mode = 442 (semaptr->ds.sem_perm.mode & ~0777) | 443 (sbuf.sem_perm.mode & 0777); 444 semaptr->ds.sem_ctime = time_second; 445 break; 446 447 case IPC_STAT: 448 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R); 449 if (eval) 450 break; 451 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 452 break; 453 eval = copyout(&semaptr->ds, real_arg.buf, 454 sizeof(struct semid_ds)); 455 break; 456 457 case GETNCNT: 458 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R); 459 if (eval) 460 break; 461 if (semnum < 0 || semnum >= semaptr->ds.sem_nsems) { 462 eval = EINVAL; 463 break; 464 } 465 rval = semaptr->ds.sem_base[semnum].semncnt; 466 break; 467 468 case GETPID: 469 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R); 470 if (eval) 471 break; 472 if (semnum < 0 || semnum >= semaptr->ds.sem_nsems) { 473 eval = EINVAL; 474 break; 475 } 476 rval = semaptr->ds.sem_base[semnum].sempid; 477 break; 478 479 case GETVAL: 480 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R); 481 if (eval) 482 break; 483 if (semnum < 0 || semnum >= semaptr->ds.sem_nsems) { 484 eval = EINVAL; 485 break; 486 } 487 rval = semaptr->ds.sem_base[semnum].semval; 488 break; 489 490 case GETALL: 491 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R); 492 if (eval) 493 break; 494 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 495 break; 496 for (i = 0; i < semaptr->ds.sem_nsems; i++) { 497 eval = copyout(&semaptr->ds.sem_base[i].semval, 498 &real_arg.array[i], 499 sizeof(real_arg.array[0])); 500 if (eval) 501 break; 502 } 503 break; 504 505 case GETZCNT: 506 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_R); 507 if (eval) 508 break; 509 if (semnum < 0 || semnum >= semaptr->ds.sem_nsems) { 510 eval = EINVAL; 511 break; 512 } 513 rval = semaptr->ds.sem_base[semnum].semzcnt; 514 break; 515 516 case SETVAL: 517 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_W); 518 if (eval) 519 break; 520 if (semnum < 0 || semnum >= semaptr->ds.sem_nsems) { 521 eval = EINVAL; 522 break; 523 } 524 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 525 break; 526 527 /* 528 * Because we hold semaptr->lk exclusively we can safely 529 * modify any semptr content without acquiring its token. 530 */ 531 semptr = &semaptr->ds.sem_base[semnum]; 532 semptr->semval = real_arg.val; 533 semundo_clear(semid, semnum); 534 if (semptr->semzcnt || semptr->semncnt) 535 wakeup(semptr); 536 break; 537 538 case SETALL: 539 eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_W); 540 if (eval) 541 break; 542 if ((eval = copyin(arg, &real_arg, sizeof(real_arg))) != 0) 543 break; 544 /* 545 * Because we hold semaptr->lk exclusively we can safely 546 * modify any semptr content without acquiring its token. 547 */ 548 for (i = 0; i < semaptr->ds.sem_nsems; i++) { 549 semptr = &semaptr->ds.sem_base[i]; 550 eval = copyin(&real_arg.array[i], 551 (caddr_t)&semptr->semval, 552 sizeof(real_arg.array[0])); 553 if (semptr->semzcnt || semptr->semncnt) 554 wakeup(semptr); 555 if (eval != 0) 556 break; 557 } 558 semundo_clear(semid, -1); 559 break; 560 561 default: 562 eval = EINVAL; 563 break; 564 } 565 lockmgr(&semaptr->lk, LK_RELEASE); 566 567 if (eval == 0) 568 uap->sysmsg_result = rval; 569 return(eval); 570 } 571 572 /* 573 * MPALMOSTSAFE 574 */ 575 int 576 sys_semget(struct semget_args *uap) 577 { 578 struct thread *td = curthread; 579 int semid, eval; 580 int key = uap->key; 581 int nsems = uap->nsems; 582 int semflg = uap->semflg; 583 struct ucred *cred = td->td_ucred; 584 585 #ifdef SEM_DEBUG 586 kprintf("semget(0x%x, %d, 0%o)\n", key, nsems, semflg); 587 #endif 588 589 if (!jail_sysvipc_allowed && cred->cr_prison != NULL) 590 return (ENOSYS); 591 592 eval = 0; 593 594 if (key != IPC_PRIVATE) { 595 for (semid = 0; semid < seminfo.semmni; semid++) { 596 if ((sema[semid].ds.sem_perm.mode & SEM_ALLOC) == 0 || 597 sema[semid].ds.sem_perm.key != key) { 598 continue; 599 } 600 lockmgr(&sema[semid].lk, LK_EXCLUSIVE); 601 if ((sema[semid].ds.sem_perm.mode & SEM_ALLOC) == 0 || 602 sema[semid].ds.sem_perm.key != key) { 603 lockmgr(&sema[semid].lk, LK_RELEASE); 604 continue; 605 } 606 break; 607 } 608 if (semid < seminfo.semmni) { 609 /* sema[semid].lk still locked from above */ 610 #ifdef SEM_DEBUG 611 kprintf("found public key\n"); 612 #endif 613 if ((eval = ipcperm(td->td_proc, 614 &sema[semid].ds.sem_perm, 615 semflg & 0700))) { 616 lockmgr(&sema[semid].lk, LK_RELEASE); 617 goto done; 618 } 619 if (nsems > 0 && sema[semid].ds.sem_nsems < nsems) { 620 #ifdef SEM_DEBUG 621 kprintf("too small\n"); 622 #endif 623 eval = EINVAL; 624 lockmgr(&sema[semid].lk, LK_RELEASE); 625 goto done; 626 } 627 if ((semflg & IPC_CREAT) && (semflg & IPC_EXCL)) { 628 #ifdef SEM_DEBUG 629 kprintf("not exclusive\n"); 630 #endif 631 eval = EEXIST; 632 lockmgr(&sema[semid].lk, LK_RELEASE); 633 goto done; 634 } 635 636 /* 637 * Return this one. 638 */ 639 lockmgr(&sema[semid].lk, LK_RELEASE); 640 goto done; 641 } 642 } 643 644 #ifdef SEM_DEBUG 645 kprintf("need to allocate the semid_ds\n"); 646 #endif 647 if (key == IPC_PRIVATE || (semflg & IPC_CREAT)) { 648 if (nsems <= 0 || nsems > seminfo.semmsl) { 649 #ifdef SEM_DEBUG 650 kprintf("nsems out of range (0<%d<=%d)\n", 651 nsems, seminfo.semmsl); 652 #endif 653 eval = EINVAL; 654 goto done; 655 } 656 657 /* 658 * SEM_ALLOC flag cannot be set unless sema_lk is locked. 659 * semtot field also protected by sema_lk. 660 */ 661 lockmgr(&sema_lk, LK_EXCLUSIVE); 662 if (nsems > seminfo.semmns - semtot) { 663 #ifdef SEM_DEBUG 664 kprintf("not enough semaphores left " 665 "(need %d, got %d)\n", 666 nsems, seminfo.semmns - semtot); 667 #endif 668 eval = ENOSPC; 669 lockmgr(&sema_lk, LK_RELEASE); 670 goto done; 671 } 672 for (semid = 0; semid < seminfo.semmni; semid++) { 673 if ((sema[semid].ds.sem_perm.mode & SEM_ALLOC) == 0) 674 break; 675 } 676 if (semid == seminfo.semmni) { 677 #ifdef SEM_DEBUG 678 kprintf("no more semid_ds's available\n"); 679 #endif 680 eval = ENOSPC; 681 lockmgr(&sema_lk, LK_RELEASE); 682 goto done; 683 } 684 #ifdef SEM_DEBUG 685 kprintf("semid %d is available\n", semid); 686 #endif 687 lockmgr(&sema[semid].lk, LK_EXCLUSIVE); 688 sema[semid].ds.sem_perm.key = key; 689 sema[semid].ds.sem_perm.cuid = cred->cr_uid; 690 sema[semid].ds.sem_perm.uid = cred->cr_uid; 691 sema[semid].ds.sem_perm.cgid = cred->cr_gid; 692 sema[semid].ds.sem_perm.gid = cred->cr_gid; 693 sema[semid].ds.sem_perm.mode = (semflg & 0777) | SEM_ALLOC; 694 sema[semid].ds.sem_perm.seq = 695 (sema[semid].ds.sem_perm.seq + 1) & 0x7fff; 696 sema[semid].ds.sem_nsems = nsems; 697 sema[semid].ds.sem_otime = 0; 698 sema[semid].ds.sem_ctime = time_second; 699 sema[semid].ds.sem_base = kmalloc(sizeof(struct sem) * nsems, 700 M_SEM, M_WAITOK|M_ZERO); 701 semtot += nsems; 702 ++sema[semid].gen; 703 lockmgr(&sema[semid].lk, LK_RELEASE); 704 lockmgr(&sema_lk, LK_RELEASE); 705 #ifdef SEM_DEBUG 706 kprintf("sembase = 0x%x, next = 0x%x\n", 707 sema[semid].ds.sem_base, &sem[semtot]); 708 #endif 709 /* eval == 0 */ 710 } else { 711 #ifdef SEM_DEBUG 712 kprintf("didn't find it and wasn't asked to create it\n"); 713 #endif 714 eval = ENOENT; 715 } 716 717 done: 718 if (eval == 0) { 719 uap->sysmsg_result = 720 IXSEQ_TO_IPCID(semid, sema[semid].ds.sem_perm); 721 } 722 return(eval); 723 } 724 725 /* 726 * MPSAFE 727 */ 728 int 729 sys_semop(struct semop_args *uap) 730 { 731 struct thread *td = curthread; 732 int semid = uap->semid; 733 u_int nsops = uap->nsops; 734 struct sembuf sops[MAX_SOPS]; 735 struct semid_pool *semaptr; 736 struct sembuf *sopptr; 737 struct sem *semptr; 738 struct sem *xsemptr; 739 int i, j, eval; 740 int do_undos; 741 742 #ifdef SEM_DEBUG 743 kprintf("call to semop(%d, 0x%x, %u)\n", semid, sops, nsops); 744 #endif 745 if (!jail_sysvipc_allowed && td->td_ucred->cr_prison != NULL) 746 return (ENOSYS); 747 748 semid = IPCID_TO_IX(semid); /* Convert back to zero origin */ 749 750 if (semid < 0 || semid >= seminfo.semmni) { 751 eval = EINVAL; 752 goto done2; 753 } 754 755 wakeup_start_delayed(); 756 semaptr = &sema[semid]; 757 lockmgr(&semaptr->lk, LK_SHARED); 758 759 if ((semaptr->ds.sem_perm.mode & SEM_ALLOC) == 0) { 760 eval = EINVAL; 761 goto done; 762 } 763 if (semaptr->ds.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) { 764 eval = EINVAL; 765 goto done; 766 } 767 768 if ((eval = ipcperm(td->td_proc, &semaptr->ds.sem_perm, IPC_W))) { 769 #ifdef SEM_DEBUG 770 kprintf("eval = %d from ipaccess\n", eval); 771 #endif 772 goto done; 773 } 774 775 if (nsops > MAX_SOPS) { 776 #ifdef SEM_DEBUG 777 kprintf("too many sops (max=%d, nsops=%u)\n", MAX_SOPS, nsops); 778 #endif 779 eval = E2BIG; 780 goto done; 781 } 782 783 if ((eval = copyin(uap->sops, &sops, nsops * sizeof(sops[0]))) != 0) { 784 #ifdef SEM_DEBUG 785 kprintf("eval = %d from copyin(%08x, %08x, %u)\n", eval, 786 uap->sops, &sops, nsops * sizeof(sops[0])); 787 #endif 788 goto done; 789 } 790 791 /* 792 * Loop trying to satisfy the vector of requests. 793 * If we reach a point where we must wait, any requests already 794 * performed are rolled back and we go to sleep until some other 795 * process wakes us up. At this point, we start all over again. 796 * 797 * This ensures that from the perspective of other tasks, a set 798 * of requests is atomic (never partially satisfied). 799 */ 800 do_undos = 0; 801 802 for (;;) { 803 long gen; 804 805 semptr = NULL; 806 807 for (i = 0; i < nsops; i++) { 808 sopptr = &sops[i]; 809 810 if (sopptr->sem_num >= semaptr->ds.sem_nsems) { 811 eval = EFBIG; 812 goto done; 813 } 814 815 semptr = &semaptr->ds.sem_base[sopptr->sem_num]; 816 lwkt_getpooltoken(semptr); 817 818 #ifdef SEM_DEBUG 819 kprintf("semop: semaptr=%x, sem_base=%x, semptr=%x, " 820 "sem[%d]=%d : op=%d, flag=%s\n", 821 semaptr, semaptr->ds.sem_base, semptr, 822 sopptr->sem_num, semptr->semval, sopptr->sem_op, 823 (sopptr->sem_flg & IPC_NOWAIT) ? "nowait" : "wait"); 824 #endif 825 826 if (sopptr->sem_op < 0) { 827 if (semptr->semval + sopptr->sem_op < 0) { 828 #ifdef SEM_DEBUG 829 kprintf("semop: can't do it now\n"); 830 #endif 831 break; 832 } else { 833 semptr->semval += sopptr->sem_op; 834 if (semptr->semval == 0 && 835 semptr->semzcnt > 0) { 836 wakeup(semptr); 837 } 838 } 839 if (sopptr->sem_flg & SEM_UNDO) 840 do_undos = 1; 841 } else if (sopptr->sem_op == 0) { 842 if (semptr->semval > 0) { 843 #ifdef SEM_DEBUG 844 kprintf("semop: not zero now\n"); 845 #endif 846 break; 847 } 848 } else { 849 semptr->semval += sopptr->sem_op; 850 if (sopptr->sem_flg & SEM_UNDO) 851 do_undos = 1; 852 if (semptr->semncnt > 0) 853 wakeup(semptr); 854 } 855 lwkt_relpooltoken(semptr); 856 } 857 858 /* 859 * Did we get through the entire vector? 860 */ 861 if (i >= nsops) 862 goto donex; 863 864 /* 865 * No, protect the semaphore request which also flags that 866 * a wakeup is needed, then release semptr since we know 867 * another process is likely going to need to access it 868 * soon. 869 */ 870 if (sopptr->sem_op == 0) 871 semptr->semzcnt++; 872 else 873 semptr->semncnt++; 874 tsleep_interlock(semptr, PCATCH); 875 lwkt_relpooltoken(semptr); 876 877 /* 878 * Rollback the semaphores we had acquired. 879 */ 880 #ifdef SEM_DEBUG 881 kprintf("semop: rollback 0 through %d\n", i-1); 882 #endif 883 for (j = 0; j < i; j++) { 884 xsemptr = &semaptr->ds.sem_base[sops[j].sem_num]; 885 lwkt_getpooltoken(xsemptr); 886 xsemptr->semval -= sops[j].sem_op; 887 if (xsemptr->semval == 0 && xsemptr->semzcnt > 0) 888 wakeup(xsemptr); 889 if (xsemptr->semval <= 0 && xsemptr->semncnt > 0) 890 wakeup(xsemptr); 891 lwkt_relpooltoken(xsemptr); 892 } 893 894 /* 895 * If the request that we couldn't satisfy has the 896 * NOWAIT flag set then return with EAGAIN. 897 */ 898 if (sopptr->sem_flg & IPC_NOWAIT) { 899 eval = EAGAIN; 900 goto done; 901 } 902 903 /* 904 * Release semaptr->lk while sleeping, allowing other 905 * semops (like SETVAL, SETALL, etc), which require an 906 * exclusive lock and might wake us up. 907 * 908 * Reload and recheck the validity of semaptr on return. 909 * Note that semptr itself might have changed too, but 910 * we've already interlocked for semptr and that is what 911 * will be woken up if it wakes up the tsleep on a MP 912 * race. 913 * 914 * gen protects against destroy/re-create races where the 915 * creds match. 916 */ 917 #ifdef SEM_DEBUG 918 kprintf("semop: good night!\n"); 919 #endif 920 gen = semaptr->gen; 921 lockmgr(&semaptr->lk, LK_RELEASE); 922 eval = tsleep(semptr, PCATCH | PINTERLOCKED, "semwait", hz); 923 lockmgr(&semaptr->lk, LK_SHARED); 924 #ifdef SEM_DEBUG 925 kprintf("semop: good morning (eval=%d)!\n", eval); 926 #endif 927 928 /* return code is checked below, after sem[nz]cnt-- */ 929 930 /* 931 * Make sure that the semaphore still exists 932 */ 933 if (semaptr->gen != gen || 934 (semaptr->ds.sem_perm.mode & SEM_ALLOC) == 0 || 935 semaptr->ds.sem_perm.seq != IPCID_TO_SEQ(uap->semid)) { 936 eval = EIDRM; 937 goto done; 938 } 939 940 /* 941 * The semaphore is still alive. Readjust the count of 942 * waiting processes. 943 */ 944 semptr = &semaptr->ds.sem_base[sopptr->sem_num]; 945 lwkt_getpooltoken(semptr); 946 if (sopptr->sem_op == 0) 947 semptr->semzcnt--; 948 else 949 semptr->semncnt--; 950 lwkt_relpooltoken(semptr); 951 952 /* 953 * Is it really morning, or was our sleep interrupted? 954 * (Delayed check of tsleep() return code because we 955 * need to decrement sem[nz]cnt either way.) 956 */ 957 if (eval) { 958 eval = EINTR; 959 goto done; 960 } 961 #ifdef SEM_DEBUG 962 kprintf("semop: good morning!\n"); 963 #endif 964 /* RETRY LOOP */ 965 } 966 967 donex: 968 /* 969 * Process any SEM_UNDO requests. 970 */ 971 if (do_undos) { 972 for (i = 0; i < nsops; i++) { 973 /* 974 * We only need to deal with SEM_UNDO's for non-zero 975 * op's. 976 */ 977 int adjval; 978 979 if ((sops[i].sem_flg & SEM_UNDO) == 0) 980 continue; 981 adjval = sops[i].sem_op; 982 if (adjval == 0) 983 continue; 984 eval = semundo_adjust(td->td_proc, semid, 985 sops[i].sem_num, -adjval); 986 if (eval == 0) 987 continue; 988 989 /* 990 * Oh-Oh! We ran out of either sem_undo's or undo's. 991 * Rollback the adjustments to this point and then 992 * rollback the semaphore ups and down so we can return 993 * with an error with all structures restored. We 994 * rollback the undo's in the exact reverse order that 995 * we applied them. This guarantees that we won't run 996 * out of space as we roll things back out. 997 */ 998 for (j = i - 1; j >= 0; j--) { 999 if ((sops[j].sem_flg & SEM_UNDO) == 0) 1000 continue; 1001 adjval = sops[j].sem_op; 1002 if (adjval == 0) 1003 continue; 1004 if (semundo_adjust(td->td_proc, semid, 1005 sops[j].sem_num, adjval) != 0) 1006 panic("semop - can't undo undos"); 1007 } 1008 1009 for (j = 0; j < nsops; j++) { 1010 xsemptr = &semaptr->ds.sem_base[ 1011 sops[j].sem_num]; 1012 lwkt_getpooltoken(xsemptr); 1013 xsemptr->semval -= sops[j].sem_op; 1014 if (xsemptr->semval == 0 && 1015 xsemptr->semzcnt > 0) 1016 wakeup(xsemptr); 1017 if (xsemptr->semval <= 0 && 1018 xsemptr->semncnt > 0) 1019 wakeup(xsemptr); 1020 lwkt_relpooltoken(xsemptr); 1021 } 1022 1023 #ifdef SEM_DEBUG 1024 kprintf("eval = %d from semundo_adjust\n", eval); 1025 #endif 1026 goto done; 1027 } /* loop through the sops */ 1028 } /* if (do_undos) */ 1029 1030 /* We're definitely done - set the sempid's */ 1031 for (i = 0; i < nsops; i++) { 1032 sopptr = &sops[i]; 1033 semptr = &semaptr->ds.sem_base[sopptr->sem_num]; 1034 lwkt_getpooltoken(semptr); 1035 semptr->sempid = td->td_proc->p_pid; 1036 lwkt_relpooltoken(semptr); 1037 } 1038 1039 /* Do a wakeup if any semaphore was up'd. */ 1040 #ifdef SEM_DEBUG 1041 kprintf("semop: done\n"); 1042 #endif 1043 uap->sysmsg_result = 0; 1044 eval = 0; 1045 done: 1046 lockmgr(&semaptr->lk, LK_RELEASE); 1047 wakeup_end_delayed(); 1048 done2: 1049 return(eval); 1050 } 1051 1052 /* 1053 * Go through the undo structures for this process and apply the adjustments to 1054 * semaphores. 1055 * 1056 * (p->p_token is held by the caller) 1057 */ 1058 void 1059 semexit(struct proc *p) 1060 { 1061 struct sem_undo *suptr; 1062 struct sem *semptr; 1063 1064 /* 1065 * We're getting a global token, don't do it if we couldn't 1066 * possibly have any semaphores. 1067 */ 1068 if ((p->p_flags & P_SYSVSEM) == 0) 1069 return; 1070 suptr = p->p_sem_undo; 1071 KKASSERT(suptr != NULL); 1072 1073 /* 1074 * Disconnect suptr from the process and increment un_refs to 1075 * prevent anyone else from being able to destroy the structure. 1076 * Do not remove it from the linked list until after we are through 1077 * scanning it as other semaphore calls might still effect it. 1078 */ 1079 lwkt_gettoken(&semu_token); 1080 p->p_sem_undo = NULL; 1081 p->p_flags &= ~P_SYSVSEM; 1082 suptr->un_proc = NULL; 1083 ++suptr->un_refs; 1084 lwkt_reltoken(&semu_token); 1085 1086 while (suptr->un_cnt) { 1087 struct semid_pool *semaptr; 1088 int semid; 1089 int semnum; 1090 int adjval; 1091 int ix; 1092 1093 /* 1094 * These values are stable because we hold p->p_token. 1095 * However, they can get ripped out from under us when 1096 * we block or obtain other tokens so we have to re-check. 1097 */ 1098 ix = suptr->un_cnt - 1; 1099 semid = suptr->un_ent[ix].un_id; 1100 semnum = suptr->un_ent[ix].un_num; 1101 adjval = suptr->un_ent[ix].un_adjval; 1102 1103 semaptr = &sema[semid]; 1104 1105 /* 1106 * Recheck after locking, then execute the undo 1107 * operation. semptr remains valid due to the 1108 * semaptr->lk. 1109 */ 1110 lockmgr(&semaptr->lk, LK_SHARED); 1111 semptr = &semaptr->ds.sem_base[semnum]; 1112 lwkt_getpooltoken(semptr); 1113 1114 if (ix == suptr->un_cnt - 1 && 1115 semid == suptr->un_ent[ix].un_id && 1116 semnum == suptr->un_ent[ix].un_num && 1117 adjval == suptr->un_ent[ix].un_adjval) { 1118 /* 1119 * Only do assertions when we aren't in a SMP race. 1120 */ 1121 if ((semaptr->ds.sem_perm.mode & SEM_ALLOC) == 0) 1122 panic("semexit - semid not allocated"); 1123 if (semnum >= semaptr->ds.sem_nsems) 1124 panic("semexit - semnum out of range"); 1125 --suptr->un_cnt; 1126 1127 if (adjval < 0) { 1128 if (semptr->semval < -adjval) 1129 semptr->semval = 0; 1130 else 1131 semptr->semval += adjval; 1132 } else { 1133 semptr->semval += adjval; 1134 } 1135 wakeup(semptr); 1136 } 1137 lwkt_relpooltoken(semptr); 1138 lockmgr(&semaptr->lk, LK_RELEASE); 1139 } 1140 1141 /* 1142 * Final cleanup, remove from the list and deallocate on the 1143 * last ref only. 1144 */ 1145 lwkt_gettoken(&semu_token); 1146 if (--suptr->un_refs == 0) { 1147 TAILQ_REMOVE(&semu_list, suptr, un_entry); 1148 KKASSERT(suptr->un_cnt == 0); 1149 kfree(suptr, M_SEM); 1150 } 1151 lwkt_reltoken(&semu_token); 1152 } 1153