1 /* $OpenBSD: kern_exit.c,v 1.139 2014/04/17 14:52:50 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 (pr->ps_refcnt > 1) 162 tsleep(&pr->ps_threads, PUSER, "thrdeath", 0); 163 if (pr->ps_flags & PS_PROFIL) 164 stopprofclock(pr); 165 } 166 167 rup = pr->ps_ru; 168 if (rup == NULL) { 169 rup = pool_get(&rusage_pool, PR_WAITOK | PR_ZERO); 170 if (pr->ps_ru == NULL) { 171 pr->ps_ru = rup; 172 } else { 173 pool_put(&rusage_pool, rup); 174 rup = pr->ps_ru; 175 } 176 } 177 p->p_siglist = 0; 178 179 /* 180 * Close open files and release open-file table. 181 */ 182 fdfree(p); 183 184 if ((p->p_flag & P_THREAD) == 0) { 185 timeout_del(&pr->ps_realit_to); 186 #ifdef SYSVSEM 187 semexit(pr); 188 #endif 189 if (SESS_LEADER(pr)) { 190 struct session *sp = pr->ps_session; 191 192 if (sp->s_ttyvp) { 193 /* 194 * Controlling process. 195 * Signal foreground pgrp, 196 * drain controlling terminal 197 * and revoke access to controlling terminal. 198 */ 199 if (sp->s_ttyp->t_session == sp) { 200 if (sp->s_ttyp->t_pgrp) 201 pgsignal(sp->s_ttyp->t_pgrp, 202 SIGHUP, 1); 203 ttywait(sp->s_ttyp); 204 /* 205 * The tty could have been revoked 206 * if we blocked. 207 */ 208 if (sp->s_ttyvp) 209 VOP_REVOKE(sp->s_ttyvp, 210 REVOKEALL); 211 } 212 ovp = sp->s_ttyvp; 213 sp->s_ttyvp = NULL; 214 if (ovp) 215 vrele(ovp); 216 /* 217 * s_ttyp is not zero'd; we use this to 218 * indicate that the session once had a 219 * controlling terminal. (for logging and 220 * informational purposes) 221 */ 222 } 223 sp->s_leader = NULL; 224 } 225 fixjobc(pr, pr->ps_pgrp, 0); 226 227 #ifdef ACCOUNTING 228 acct_process(p); 229 #endif 230 231 #ifdef KTRACE 232 /* release trace file */ 233 if (pr->ps_tracevp) 234 ktrcleartrace(pr); 235 #endif 236 237 /* 238 * If parent has the SAS_NOCLDWAIT flag set, we're not 239 * going to become a zombie. 240 */ 241 if (pr->ps_pptr->ps_sigacts->ps_flags & SAS_NOCLDWAIT) 242 atomic_setbits_int(&pr->ps_flags, PS_NOZOMBIE); 243 } 244 245 #if NSYSTRACE > 0 246 if (ISSET(p->p_flag, P_SYSTRACE)) 247 systrace_exit(p); 248 #endif 249 250 /* 251 * If emulation has thread exit hook, call it now. 252 */ 253 if (pr->ps_emul->e_proc_exit) 254 (*pr->ps_emul->e_proc_exit)(p); 255 256 /* 257 * Remove proc from pidhash chain and allproc so looking 258 * it up won't work. We will put the proc on the 259 * deadproc list later (using the p_hash member), and 260 * wake up the reaper when we do. If this is the last 261 * thread of a process that isn't PS_NOZOMBIE, we'll put 262 * the process on the zombprocess list below. 263 */ 264 /* 265 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 266 */ 267 p->p_stat = SDEAD; 268 269 LIST_REMOVE(p, p_hash); 270 LIST_REMOVE(p, p_list); 271 272 if ((p->p_flag & P_THREAD) == 0) { 273 LIST_REMOVE(pr, ps_list); 274 275 if ((pr->ps_flags & PS_NOZOMBIE) == 0) 276 LIST_INSERT_HEAD(&zombprocess, pr, ps_list); 277 else { 278 /* 279 * Not going to be a zombie, so it's now off all 280 * the lists scanned by ispidtaken(), so block 281 * fast reuse of the pid now. 282 */ 283 freepid(p->p_pid); 284 } 285 286 /* 287 * Give orphaned children to init(8). 288 */ 289 qr = LIST_FIRST(&pr->ps_children); 290 if (qr) /* only need this if any child is S_ZOMB */ 291 wakeup(initproc->p_p); 292 for (; qr != 0; qr = nqr) { 293 nqr = LIST_NEXT(qr, ps_sibling); 294 proc_reparent(qr, initproc->p_p); 295 /* 296 * Traced processes are killed since their 297 * existence means someone is screwing up. 298 */ 299 if (qr->ps_flags & PS_TRACED && 300 !(qr->ps_flags & PS_EXITING)) { 301 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 302 /* 303 * If single threading is active, 304 * direct the signal to the active 305 * thread to avoid deadlock. 306 */ 307 if (qr->ps_single) 308 ptsignal(qr->ps_single, SIGKILL, 309 STHREAD); 310 else 311 prsignal(qr, SIGKILL); 312 } 313 } 314 } 315 316 /* add thread's accumulated rusage into the process's total */ 317 ruadd(rup, &p->p_ru); 318 tuagg(pr, p); 319 320 /* 321 * clear %cpu usage during swap 322 */ 323 p->p_pctcpu = 0; 324 325 if ((p->p_flag & P_THREAD) == 0) { 326 /* 327 * Final thread has died, so add on our children's rusage 328 * and calculate the total times 329 */ 330 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 331 ruadd(rup, &pr->ps_cru); 332 333 /* notify interested parties of our demise and clean up */ 334 knote_processexit(pr); 335 336 /* 337 * Notify parent that we're gone. If we're not going to 338 * become a zombie, reparent to process 1 (init) so that 339 * we can wake our original parent to possibly unblock 340 * wait4() to return ECHILD. 341 */ 342 if (pr->ps_flags & PS_NOZOMBIE) { 343 struct process *ppr = pr->ps_pptr; 344 proc_reparent(pr, initproc->p_p); 345 wakeup(ppr); 346 } 347 348 /* 349 * Release the process's signal state. 350 */ 351 sigactsfree(pr); 352 } 353 354 /* just a thread? detach it from its process */ 355 if (p->p_flag & P_THREAD) { 356 /* scheduler_wait_hook(pr->ps_mainproc, p); XXX */ 357 if (--pr->ps_refcnt == 1) 358 wakeup(&pr->ps_threads); 359 KASSERT(pr->ps_refcnt > 0); 360 } 361 362 /* 363 * Other substructures are freed from reaper and wait(). 364 */ 365 366 /* 367 * Finally, call machine-dependent code to switch to a new 368 * context (possibly the idle context). Once we are no longer 369 * using the dead process's vmspace and stack, exit2() will be 370 * called to schedule those resources to be released by the 371 * reaper thread. 372 * 373 * Note that cpu_exit() will end with a call equivalent to 374 * cpu_switch(), finishing our execution (pun intended). 375 */ 376 uvmexp.swtch++; 377 cpu_exit(p); 378 panic("cpu_exit returned"); 379 } 380 381 /* 382 * Locking of this proclist is special; it's accessed in a 383 * critical section of process exit, and thus locking it can't 384 * modify interrupt state. We use a simple spin lock for this 385 * proclist. We use the p_hash member to linkup to deadproc. 386 */ 387 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 388 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 389 390 /* 391 * We are called from cpu_exit() once it is safe to schedule the 392 * dead process's resources to be freed. 393 * 394 * NOTE: One must be careful with locking in this routine. It's 395 * called from a critical section in machine-dependent code, so 396 * we should refrain from changing any interrupt state. 397 * 398 * We lock the deadproc list, place the proc on that list (using 399 * the p_hash member), and wake up the reaper. 400 */ 401 void 402 exit2(struct proc *p) 403 { 404 mtx_enter(&deadproc_mutex); 405 LIST_INSERT_HEAD(&deadproc, p, p_hash); 406 mtx_leave(&deadproc_mutex); 407 408 wakeup(&deadproc); 409 } 410 411 void 412 proc_free(struct proc *p) 413 { 414 pool_put(&proc_pool, p); 415 nthreads--; 416 } 417 418 /* 419 * Process reaper. This is run by a kernel thread to free the resources 420 * of a dead process. Once the resources are free, the process becomes 421 * a zombie, and the parent is allowed to read the undead's status. 422 */ 423 void 424 reaper(void) 425 { 426 struct proc *p; 427 428 KERNEL_UNLOCK(); 429 430 SCHED_ASSERT_UNLOCKED(); 431 432 for (;;) { 433 mtx_enter(&deadproc_mutex); 434 while ((p = LIST_FIRST(&deadproc)) == NULL) 435 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 436 437 /* Remove us from the deadproc list. */ 438 LIST_REMOVE(p, p_hash); 439 mtx_leave(&deadproc_mutex); 440 441 KERNEL_LOCK(); 442 443 /* 444 * Free the VM resources we're still holding on to. 445 * We must do this from a valid thread because doing 446 * so may block. 447 */ 448 uvm_exit(p); 449 450 if (p->p_flag & P_THREAD) { 451 /* Just a thread */ 452 proc_free(p); 453 } else { 454 struct process *pr = p->p_p; 455 456 if ((pr->ps_flags & PS_NOZOMBIE) == 0) { 457 /* Process is now a true zombie. */ 458 p->p_stat = SZOMB; 459 prsignal(pr->ps_pptr, SIGCHLD); 460 461 /* Wake up the parent so it can get exit status. */ 462 wakeup(pr->ps_pptr); 463 } else { 464 /* No one will wait for us. Just zap the process now */ 465 process_zap(pr); 466 } 467 } 468 469 KERNEL_UNLOCK(); 470 } 471 } 472 473 int 474 sys_wait4(struct proc *q, void *v, register_t *retval) 475 { 476 struct sys_wait4_args /* { 477 syscallarg(pid_t) pid; 478 syscallarg(int *) status; 479 syscallarg(int) options; 480 syscallarg(struct rusage *) rusage; 481 } */ *uap = v; 482 struct rusage ru; 483 int status, error; 484 485 error = dowait4(q, SCARG(uap, pid), 486 SCARG(uap, status) ? &status : NULL, 487 SCARG(uap, options), SCARG(uap, rusage) ? &ru : NULL, retval); 488 if (error == 0 && SCARG(uap, status)) { 489 error = copyout(&status, SCARG(uap, status), sizeof(status)); 490 } 491 if (error == 0 && SCARG(uap, rusage)) { 492 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 493 #ifdef KTRACE 494 if (error == 0 && KTRPOINT(q, KTR_STRUCT)) 495 ktrrusage(q, &ru); 496 #endif 497 } 498 return (error); 499 } 500 501 int 502 dowait4(struct proc *q, pid_t pid, int *statusp, int options, 503 struct rusage *rusage, register_t *retval) 504 { 505 int nfound; 506 struct process *pr; 507 struct proc *p; 508 int error; 509 510 if (pid == 0) 511 pid = -q->p_p->ps_pgid; 512 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED)) 513 return (EINVAL); 514 515 loop: 516 nfound = 0; 517 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 518 p = pr->ps_mainproc; 519 if ((pr->ps_flags & PS_NOZOMBIE) || 520 (pid != WAIT_ANY && 521 p->p_pid != pid && 522 pr->ps_pgid != -pid)) 523 continue; 524 525 nfound++; 526 if (p->p_stat == SZOMB) { 527 retval[0] = p->p_pid; 528 529 if (statusp != NULL) 530 *statusp = p->p_xstat; /* convert to int */ 531 if (rusage != NULL) 532 memcpy(rusage, pr->ps_ru, sizeof(*rusage)); 533 proc_finish_wait(q, p); 534 return (0); 535 } 536 if (pr->ps_flags & PS_TRACED && 537 (pr->ps_flags & PS_WAITED) == 0 && pr->ps_single && 538 pr->ps_single->p_stat == SSTOP && 539 (pr->ps_single->p_flag & P_SUSPSINGLE) == 0) { 540 single_thread_wait(pr); 541 542 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 543 retval[0] = p->p_pid; 544 545 if (statusp != NULL) 546 *statusp = W_STOPCODE(pr->ps_single->p_xstat); 547 return (0); 548 } 549 if (p->p_stat == SSTOP && 550 (pr->ps_flags & PS_WAITED) == 0 && 551 (p->p_flag & P_SUSPSINGLE) == 0 && 552 (pr->ps_flags & PS_TRACED || 553 options & WUNTRACED)) { 554 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 555 retval[0] = p->p_pid; 556 557 if (statusp != NULL) 558 *statusp = W_STOPCODE(p->p_xstat); 559 return (0); 560 } 561 if ((options & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 562 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 563 retval[0] = p->p_pid; 564 565 if (statusp != NULL) 566 *statusp = _WCONTINUED; 567 return (0); 568 } 569 } 570 if (nfound == 0) 571 return (ECHILD); 572 if (options & WNOHANG) { 573 retval[0] = 0; 574 return (0); 575 } 576 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 577 return (error); 578 goto loop; 579 } 580 581 void 582 proc_finish_wait(struct proc *waiter, struct proc *p) 583 { 584 struct process *pr, *tr; 585 struct rusage *rup; 586 587 /* 588 * If we got the child via a ptrace 'attach', 589 * we need to give it back to the old parent. 590 */ 591 pr = p->p_p; 592 if (pr->ps_oppid && (tr = prfind(pr->ps_oppid))) { 593 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 594 pr->ps_oppid = 0; 595 proc_reparent(pr, tr); 596 prsignal(tr, SIGCHLD); 597 wakeup(tr); 598 } else { 599 scheduler_wait_hook(waiter, p); 600 p->p_xstat = 0; 601 rup = &waiter->p_p->ps_cru; 602 ruadd(rup, pr->ps_ru); 603 LIST_REMOVE(pr, ps_list); /* off zombprocess */ 604 freepid(p->p_pid); 605 process_zap(pr); 606 } 607 } 608 609 /* 610 * make process 'parent' the new parent of process 'child'. 611 */ 612 void 613 proc_reparent(struct process *child, struct process *parent) 614 { 615 616 if (child->ps_pptr == parent) 617 return; 618 619 LIST_REMOVE(child, ps_sibling); 620 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 621 child->ps_pptr = parent; 622 } 623 624 void 625 process_zap(struct process *pr) 626 { 627 struct vnode *otvp; 628 struct proc *p = pr->ps_mainproc; 629 630 /* 631 * Finally finished with old proc entry. 632 * Unlink it from its process group and free it. 633 */ 634 leavepgrp(pr); 635 LIST_REMOVE(pr, ps_sibling); 636 637 /* 638 * Decrement the count of procs running with this uid. 639 */ 640 (void)chgproccnt(pr->ps_ucred->cr_ruid, -1); 641 642 /* 643 * Release reference to text vnode 644 */ 645 otvp = pr->ps_textvp; 646 pr->ps_textvp = NULL; 647 if (otvp) 648 vrele(otvp); 649 650 KASSERT(pr->ps_refcnt == 1); 651 if (pr->ps_ptstat != NULL) 652 free(pr->ps_ptstat, M_SUBPROC); 653 pool_put(&rusage_pool, pr->ps_ru); 654 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 655 limfree(pr->ps_limit); 656 crfree(pr->ps_ucred); 657 pool_put(&process_pool, pr); 658 nprocesses--; 659 660 proc_free(p); 661 } 662