1 /* $OpenBSD: kern_exit.c,v 1.126 2013/08/13 05:52:23 guenther Exp $ */ 2 /* $NetBSD: kern_exit.c,v 1.39 1996/04/22 01:38:25 christos Exp $ */ 3 4 /* 5 * Copyright (c) 1982, 1986, 1989, 1991, 1993 6 * The Regents of the University of California. All rights reserved. 7 * (c) UNIX System Laboratories, Inc. 8 * All or some portions of this file are derived from material licensed 9 * to the University of California by American Telephone and Telegraph 10 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 11 * the permission of UNIX System Laboratories, Inc. 12 * 13 * Redistribution and use in source and binary forms, with or without 14 * modification, are permitted provided that the following conditions 15 * are met: 16 * 1. Redistributions of source code must retain the above copyright 17 * notice, this list of conditions and the following disclaimer. 18 * 2. Redistributions in binary form must reproduce the above copyright 19 * notice, this list of conditions and the following disclaimer in the 20 * documentation and/or other materials provided with the distribution. 21 * 3. Neither the name of the University nor the names of its contributors 22 * may be used to endorse or promote products derived from this software 23 * without specific prior written permission. 24 * 25 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 26 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 27 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 28 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 29 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 30 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 31 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 32 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 33 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 34 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 35 * SUCH DAMAGE. 36 * 37 * @(#)kern_exit.c 8.7 (Berkeley) 2/12/94 38 */ 39 40 #include <sys/param.h> 41 #include <sys/systm.h> 42 #include <sys/ioctl.h> 43 #include <sys/proc.h> 44 #include <sys/tty.h> 45 #include <sys/time.h> 46 #include <sys/resource.h> 47 #include <sys/kernel.h> 48 #include <sys/buf.h> 49 #include <sys/wait.h> 50 #include <sys/file.h> 51 #include <sys/vnode.h> 52 #include <sys/syslog.h> 53 #include <sys/malloc.h> 54 #include <sys/resourcevar.h> 55 #include <sys/ptrace.h> 56 #include <sys/acct.h> 57 #include <sys/filedesc.h> 58 #include <sys/signalvar.h> 59 #include <sys/sched.h> 60 #include <sys/ktrace.h> 61 #include <sys/pool.h> 62 #include <sys/mutex.h> 63 #ifdef SYSVSEM 64 #include <sys/sem.h> 65 #endif 66 67 #include "systrace.h" 68 #include <dev/systrace.h> 69 70 #include <sys/mount.h> 71 #include <sys/syscallargs.h> 72 73 74 #include <uvm/uvm_extern.h> 75 76 /* 77 * exit -- 78 * Death of process. 79 */ 80 int 81 sys_exit(struct proc *p, void *v, register_t *retval) 82 { 83 struct sys_exit_args /* { 84 syscallarg(int) rval; 85 } */ *uap = v; 86 87 exit1(p, W_EXITCODE(SCARG(uap, rval), 0), EXIT_NORMAL); 88 /* NOTREACHED */ 89 return (0); 90 } 91 92 int 93 sys___threxit(struct proc *p, void *v, register_t *retval) 94 { 95 struct sys___threxit_args /* { 96 syscallarg(pid_t *) notdead; 97 } */ *uap = v; 98 99 if (SCARG(uap, notdead) != NULL) { 100 pid_t zero = 0; 101 if (copyout(&zero, SCARG(uap, notdead), sizeof(zero))) 102 psignal(p, SIGSEGV); 103 } 104 exit1(p, 0, EXIT_THREAD); 105 106 return (0); 107 } 108 109 /* 110 * Exit: deallocate address space and other resources, change proc state 111 * to zombie, and unlink proc from allproc and parent's lists. Save exit 112 * status and rusage for wait(). Check for child processes and orphan them. 113 */ 114 void 115 exit1(struct proc *p, int rv, int flags) 116 { 117 struct process *pr, *qr, *nqr; 118 struct rusage *rup; 119 struct vnode *ovp; 120 121 if (p->p_pid == 1) 122 panic("init died (signal %d, exit %d)", 123 WTERMSIG(rv), WEXITSTATUS(rv)); 124 125 atomic_setbits_int(&p->p_flag, P_WEXIT); 126 127 pr = p->p_p; 128 129 /* single-threaded? */ 130 if (TAILQ_FIRST(&pr->ps_threads) == p && 131 TAILQ_NEXT(p, p_thr_link) == NULL) { 132 flags = EXIT_NORMAL; 133 } else { 134 /* nope, multi-threaded */ 135 if (flags == EXIT_NORMAL) 136 single_thread_set(p, SINGLE_EXIT, 0); 137 else if (flags == EXIT_THREAD) 138 single_thread_check(p, 0); 139 } 140 141 if (flags == EXIT_NORMAL) { 142 atomic_setbits_int(&pr->ps_flags, PS_EXITING); 143 pr->ps_mainproc->p_xstat = rv; 144 145 /* 146 * If parent is waiting for us to exit or exec, PS_PPWAIT 147 * is set; we wake up the parent early to avoid deadlock. 148 */ 149 if (pr->ps_flags & PS_PPWAIT) { 150 atomic_clearbits_int(&pr->ps_flags, PS_PPWAIT); 151 atomic_clearbits_int(&pr->ps_pptr->ps_flags, 152 PS_ISPWAIT); 153 wakeup(pr->ps_pptr); 154 } 155 } 156 157 /* unlink ourselves from the active threads */ 158 TAILQ_REMOVE(&pr->ps_threads, p, p_thr_link); 159 if ((p->p_flag & P_THREAD) == 0) { 160 /* main thread gotta wait because it has the pid, et al */ 161 while (!TAILQ_EMPTY(&pr->ps_threads)) 162 tsleep(&pr->ps_threads, PUSER, "thrdeath", 0); 163 if (pr->ps_flags & PS_PROFIL) 164 stopprofclock(pr); 165 } else if (TAILQ_EMPTY(&pr->ps_threads)) { 166 wakeup(&pr->ps_threads); 167 } 168 169 rup = pr->ps_ru; 170 if (rup == NULL) { 171 rup = pool_get(&rusage_pool, PR_WAITOK | PR_ZERO); 172 if (pr->ps_ru == NULL) { 173 pr->ps_ru = rup; 174 } else { 175 pool_put(&rusage_pool, rup); 176 rup = pr->ps_ru; 177 } 178 } 179 p->p_siglist = 0; 180 181 /* 182 * Close open files and release open-file table. 183 */ 184 fdfree(p); 185 186 if ((p->p_flag & P_THREAD) == 0) { 187 timeout_del(&pr->ps_realit_to); 188 timeout_del(&pr->ps_virt_to); 189 timeout_del(&pr->ps_prof_to); 190 #ifdef SYSVSEM 191 semexit(pr); 192 #endif 193 if (SESS_LEADER(pr)) { 194 struct session *sp = pr->ps_session; 195 196 if (sp->s_ttyvp) { 197 /* 198 * Controlling process. 199 * Signal foreground pgrp, 200 * drain controlling terminal 201 * and revoke access to controlling terminal. 202 */ 203 if (sp->s_ttyp->t_session == sp) { 204 if (sp->s_ttyp->t_pgrp) 205 pgsignal(sp->s_ttyp->t_pgrp, 206 SIGHUP, 1); 207 ttywait(sp->s_ttyp); 208 /* 209 * The tty could have been revoked 210 * if we blocked. 211 */ 212 if (sp->s_ttyvp) 213 VOP_REVOKE(sp->s_ttyvp, 214 REVOKEALL); 215 } 216 ovp = sp->s_ttyvp; 217 sp->s_ttyvp = NULL; 218 if (ovp) 219 vrele(ovp); 220 /* 221 * s_ttyp is not zero'd; we use this to 222 * indicate that the session once had a 223 * controlling terminal. (for logging and 224 * informational purposes) 225 */ 226 } 227 sp->s_leader = NULL; 228 } 229 fixjobc(pr, pr->ps_pgrp, 0); 230 231 #ifdef ACCOUNTING 232 acct_process(p); 233 #endif 234 235 #ifdef KTRACE 236 /* release trace file */ 237 if (pr->ps_tracevp) 238 ktrcleartrace(pr); 239 #endif 240 } 241 242 #if NSYSTRACE > 0 243 if (ISSET(p->p_flag, P_SYSTRACE)) 244 systrace_exit(p); 245 #endif 246 247 /* 248 * If emulation has process exit hook, call it now. 249 */ 250 if (p->p_emul->e_proc_exit) 251 (*p->p_emul->e_proc_exit)(p); 252 253 /* 254 * Remove proc from pidhash chain so looking it up won't 255 * work. Move it from allproc to zombproc, but do not yet 256 * wake up the reaper. We will put the proc on the 257 * deadproc list later (using the p_hash member), and 258 * wake up the reaper when we do. 259 */ 260 /* 261 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 262 */ 263 p->p_stat = SDEAD; 264 265 LIST_REMOVE(p, p_hash); 266 LIST_REMOVE(p, p_list); 267 LIST_INSERT_HEAD(&zombproc, p, p_list); 268 269 /* 270 * Give orphaned children to init(8). 271 */ 272 if ((p->p_flag & P_THREAD) == 0) { 273 qr = LIST_FIRST(&pr->ps_children); 274 if (qr) /* only need this if any child is S_ZOMB */ 275 wakeup(initproc->p_p); 276 for (; qr != 0; qr = nqr) { 277 nqr = LIST_NEXT(qr, ps_sibling); 278 proc_reparent(qr, initproc->p_p); 279 /* 280 * Traced processes are killed since their 281 * existence means someone is screwing up. 282 */ 283 if (qr->ps_flags & PS_TRACED && 284 !(qr->ps_flags & PS_EXITING)) { 285 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 286 /* 287 * If single threading is active, 288 * direct the signal to the active 289 * thread to avoid deadlock. 290 */ 291 if (qr->ps_single) 292 ptsignal(qr->ps_single, SIGKILL, 293 STHREAD); 294 else 295 prsignal(qr, SIGKILL); 296 } 297 } 298 } 299 300 301 /* add thread's accumulated rusage into the process's total */ 302 ruadd(rup, &p->p_ru); 303 304 /* 305 * clear %cpu usage during swap 306 */ 307 p->p_pctcpu = 0; 308 309 if ((p->p_flag & P_THREAD) == 0) { 310 /* 311 * Final thread has died, so add on our children's rusage 312 * and calculate the total times 313 */ 314 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 315 ruadd(rup, &pr->ps_cru); 316 317 /* notify interested parties of our demise and clean up */ 318 knote_processexit(pr); 319 320 /* 321 * Notify parent that we're gone. If we have P_NOZOMBIE 322 * or parent has the SAS_NOCLDWAIT flag set, notify process 1 323 * instead (and hope it will handle this situation). 324 */ 325 if ((p->p_flag & P_NOZOMBIE) || 326 (pr->ps_pptr->ps_mainproc->p_sigacts->ps_flags & 327 SAS_NOCLDWAIT)) { 328 struct process *ppr = pr->ps_pptr; 329 proc_reparent(pr, initproc->p_p); 330 331 /* 332 * Notify parent, so in case he was wait(2)ing or 333 * executing waitpid(2) with our pid, he will 334 * continue. 335 */ 336 wakeup(ppr); 337 } 338 } 339 340 /* 341 * Release the process's signal state. 342 */ 343 sigactsfree(p); 344 345 /* 346 * Other substructures are freed from reaper and wait(). 347 */ 348 349 /* 350 * Finally, call machine-dependent code to switch to a new 351 * context (possibly the idle context). Once we are no longer 352 * using the dead process's vmspace and stack, exit2() will be 353 * called to schedule those resources to be released by the 354 * reaper thread. 355 * 356 * Note that cpu_exit() will end with a call equivalent to 357 * cpu_switch(), finishing our execution (pun intended). 358 */ 359 uvmexp.swtch++; 360 cpu_exit(p); 361 panic("cpu_exit returned"); 362 } 363 364 /* 365 * Locking of this proclist is special; it's accessed in a 366 * critical section of process exit, and thus locking it can't 367 * modify interrupt state. We use a simple spin lock for this 368 * proclist. Processes on this proclist are also on zombproc; 369 * we use the p_hash member to linkup to deadproc. 370 */ 371 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 372 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 373 374 /* 375 * We are called from cpu_exit() once it is safe to schedule the 376 * dead process's resources to be freed. 377 * 378 * NOTE: One must be careful with locking in this routine. It's 379 * called from a critical section in machine-dependent code, so 380 * we should refrain from changing any interrupt state. 381 * 382 * We lock the deadproc list, place the proc on that list (using 383 * the p_hash member), and wake up the reaper. 384 */ 385 void 386 exit2(struct proc *p) 387 { 388 mtx_enter(&deadproc_mutex); 389 LIST_INSERT_HEAD(&deadproc, p, p_hash); 390 mtx_leave(&deadproc_mutex); 391 392 wakeup(&deadproc); 393 } 394 395 /* 396 * Process reaper. This is run by a kernel thread to free the resources 397 * of a dead process. Once the resources are free, the process becomes 398 * a zombie, and the parent is allowed to read the undead's status. 399 */ 400 void 401 reaper(void) 402 { 403 struct proc *p; 404 405 KERNEL_UNLOCK(); 406 407 SCHED_ASSERT_UNLOCKED(); 408 409 for (;;) { 410 mtx_enter(&deadproc_mutex); 411 while ((p = LIST_FIRST(&deadproc)) == NULL) 412 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 413 414 /* Remove us from the deadproc list. */ 415 LIST_REMOVE(p, p_hash); 416 mtx_leave(&deadproc_mutex); 417 418 KERNEL_LOCK(); 419 420 /* 421 * Free the VM resources we're still holding on to. 422 * We must do this from a valid thread because doing 423 * so may block. 424 */ 425 uvm_exit(p); 426 427 /* Process is now a true zombie. */ 428 if ((p->p_flag & P_NOZOMBIE) == 0) { 429 p->p_stat = SZOMB; 430 431 if (P_EXITSIG(p) != 0) 432 prsignal(p->p_p->ps_pptr, P_EXITSIG(p)); 433 /* Wake up the parent so it can get exit status. */ 434 wakeup(p->p_p->ps_pptr); 435 } else { 436 /* Noone will wait for us. Just zap the process now */ 437 proc_zap(p); 438 } 439 440 KERNEL_UNLOCK(); 441 } 442 } 443 444 int dowait4(struct proc *, pid_t, int *, int, struct rusage *, 445 register_t *); 446 447 int 448 sys_wait4(struct proc *q, void *v, register_t *retval) 449 { 450 struct sys_wait4_args /* { 451 syscallarg(pid_t) pid; 452 syscallarg(int *) status; 453 syscallarg(int) options; 454 syscallarg(struct rusage *) rusage; 455 } */ *uap = v; 456 struct rusage ru; 457 int error; 458 459 error = dowait4(q, SCARG(uap, pid), SCARG(uap, status), 460 SCARG(uap, options), SCARG(uap, rusage) ? &ru : NULL, retval); 461 if (error == 0 && SCARG(uap, rusage)) { 462 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 463 } 464 return (error); 465 } 466 467 #ifdef T32 468 int 469 t32_sys_wait4(struct proc *q, void *v, register_t *retval) 470 { 471 struct t32_sys_wait4_args /* { 472 syscallarg(pid_t) pid; 473 syscallarg(int *) status; 474 syscallarg(int) options; 475 syscallarg(struct rusage32 *) rusage; 476 } */ *uap = v; 477 struct rusage ru; 478 int error; 479 480 error = dowait4(q, SCARG(uap, pid), SCARG(uap, status), 481 SCARG(uap, options), SCARG(uap, rusage) ? &ru : NULL, retval); 482 if (error == 0 && SCARG(uap, rusage)) { 483 struct rusage32 ru32; 484 485 RUSAGE_TO_32(&ru32, &ru); 486 error = copyout(&ru32, SCARG(uap, rusage), sizeof(ru32)); 487 } 488 return (error); 489 } 490 #endif 491 492 int 493 dowait4(struct proc *q, pid_t pid, int *statusp, int options, 494 struct rusage *rusage, register_t *retval) 495 { 496 int nfound; 497 struct process *pr; 498 struct proc *p; 499 int status, error; 500 501 if (pid == 0) 502 pid = -q->p_p->ps_pgid; 503 if (options &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 504 return (EINVAL); 505 506 loop: 507 nfound = 0; 508 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 509 p = pr->ps_mainproc; 510 if ((p->p_flag & P_NOZOMBIE) || 511 (pid != WAIT_ANY && 512 p->p_pid != pid && 513 pr->ps_pgid != -pid)) 514 continue; 515 516 /* 517 * Wait for processes with p_exitsig != SIGCHLD processes only 518 * if WALTSIG is set; wait for processes with pexitsig == 519 * SIGCHLD only if WALTSIG is clear. 520 */ 521 if ((options & WALTSIG) ? 522 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 523 continue; 524 525 nfound++; 526 if (p->p_stat == SZOMB) { 527 retval[0] = p->p_pid; 528 529 if (statusp != NULL) { 530 status = p->p_xstat; /* convert to int */ 531 error = copyout(&status, 532 statusp, sizeof(status)); 533 if (error) 534 return (error); 535 } 536 if (rusage != NULL) 537 memcpy(rusage, pr->ps_ru, sizeof(*rusage)); 538 proc_finish_wait(q, p); 539 return (0); 540 } 541 if (pr->ps_flags & PS_TRACED && 542 (pr->ps_flags & PS_WAITED) == 0 && pr->ps_single && 543 pr->ps_single->p_stat == SSTOP && 544 (pr->ps_single->p_flag & P_SUSPSINGLE) == 0) { 545 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 546 retval[0] = p->p_pid; 547 548 if (statusp != NULL) { 549 status = W_STOPCODE(pr->ps_single->p_xstat); 550 error = copyout(&status, statusp, 551 sizeof(status)); 552 } else 553 error = 0; 554 return (error); 555 } 556 if (p->p_stat == SSTOP && 557 (pr->ps_flags & PS_WAITED) == 0 && 558 (p->p_flag & P_SUSPSINGLE) == 0 && 559 (pr->ps_flags & PS_TRACED || 560 options & WUNTRACED)) { 561 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 562 retval[0] = p->p_pid; 563 564 if (statusp != NULL) { 565 status = W_STOPCODE(p->p_xstat); 566 error = copyout(&status, statusp, 567 sizeof(status)); 568 } else 569 error = 0; 570 return (error); 571 } 572 if ((options & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 573 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 574 retval[0] = p->p_pid; 575 576 if (statusp != NULL) { 577 status = _WCONTINUED; 578 error = copyout(&status, statusp, 579 sizeof(status)); 580 } else 581 error = 0; 582 return (error); 583 } 584 } 585 if (nfound == 0) 586 return (ECHILD); 587 if (options & WNOHANG) { 588 retval[0] = 0; 589 return (0); 590 } 591 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 592 return (error); 593 goto loop; 594 } 595 596 void 597 proc_finish_wait(struct proc *waiter, struct proc *p) 598 { 599 struct process *pr, *tr; 600 struct rusage *rup; 601 602 /* 603 * If we got the child via a ptrace 'attach', 604 * we need to give it back to the old parent. 605 */ 606 pr = p->p_p; 607 if ((p->p_flag & P_THREAD) == 0 && pr->ps_oppid && 608 (tr = prfind(pr->ps_oppid))) { 609 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 610 pr->ps_oppid = 0; 611 proc_reparent(pr, tr); 612 if (p->p_exitsig != 0) 613 prsignal(tr, p->p_exitsig); 614 wakeup(tr); 615 } else { 616 scheduler_wait_hook(waiter, p); 617 p->p_xstat = 0; 618 rup = &waiter->p_p->ps_cru; 619 ruadd(rup, pr->ps_ru); 620 proc_zap(p); 621 } 622 } 623 624 /* 625 * make process 'parent' the new parent of process 'child'. 626 */ 627 void 628 proc_reparent(struct process *child, struct process *parent) 629 { 630 631 if (child->ps_pptr == parent) 632 return; 633 634 if (parent == initproc->p_p) 635 child->ps_mainproc->p_exitsig = SIGCHLD; 636 637 LIST_REMOVE(child, ps_sibling); 638 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 639 child->ps_pptr = parent; 640 } 641 642 void 643 proc_zap(struct proc *p) 644 { 645 struct process *pr = p->p_p; 646 struct vnode *otvp; 647 648 /* 649 * Finally finished with old proc entry. 650 * Unlink it from its process group and free it. 651 */ 652 if ((p->p_flag & P_THREAD) == 0) 653 leavepgrp(pr); 654 LIST_REMOVE(p, p_list); /* off zombproc */ 655 if ((p->p_flag & P_THREAD) == 0) { 656 LIST_REMOVE(pr, ps_sibling); 657 658 /* 659 * Decrement the count of procs running with this uid. 660 */ 661 (void)chgproccnt(p->p_cred->p_ruid, -1); 662 } 663 664 /* 665 * Release reference to text vnode 666 */ 667 otvp = p->p_textvp; 668 p->p_textvp = NULL; 669 if (otvp) 670 vrele(otvp); 671 672 /* 673 * Remove us from our process list, possibly killing the process 674 * in the process (pun intended). 675 */ 676 if (--pr->ps_refcnt == 0) { 677 if (pr->ps_ptstat != NULL) 678 free(pr->ps_ptstat, M_SUBPROC); 679 pool_put(&rusage_pool, pr->ps_ru); 680 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 681 limfree(pr->ps_limit); 682 crfree(pr->ps_cred->pc_ucred); 683 pool_put(&pcred_pool, pr->ps_cred); 684 pool_put(&process_pool, pr); 685 nprocesses--; 686 } 687 688 freepid(p->p_pid); 689 pool_put(&proc_pool, p); 690 nthreads--; 691 } 692