1 /* $OpenBSD: kern_exit.c,v 1.119 2012/09/08 14:52:00 kettenis 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 #include <machine/cpu.h> 74 75 #include <uvm/uvm_extern.h> 76 77 /* 78 * exit -- 79 * Death of process. 80 */ 81 int 82 sys_exit(struct proc *p, void *v, register_t *retval) 83 { 84 struct sys_exit_args /* { 85 syscallarg(int) rval; 86 } */ *uap = v; 87 88 exit1(p, W_EXITCODE(SCARG(uap, rval), 0), EXIT_NORMAL); 89 /* NOTREACHED */ 90 return (0); 91 } 92 93 int 94 sys___threxit(struct proc *p, void *v, register_t *retval) 95 { 96 struct sys___threxit_args /* { 97 syscallarg(pid_t *) notdead; 98 } */ *uap = v; 99 100 if (!rthreads_enabled) 101 return (EINVAL); 102 103 if (SCARG(uap, notdead) != NULL) { 104 pid_t zero = 0; 105 if (copyout(&zero, SCARG(uap, notdead), sizeof(zero))) { 106 psignal(p, SIGSEGV); 107 } 108 } 109 exit1(p, 0, EXIT_THREAD); 110 111 return (0); 112 } 113 114 /* 115 * Exit: deallocate address space and other resources, change proc state 116 * to zombie, and unlink proc from allproc and parent's lists. Save exit 117 * status and rusage for wait(). Check for child processes and orphan them. 118 */ 119 void 120 exit1(struct proc *p, int rv, int flags) 121 { 122 struct process *pr, *qr, *nqr; 123 struct rusage *rup; 124 125 if (p->p_pid == 1) 126 panic("init died (signal %d, exit %d)", 127 WTERMSIG(rv), WEXITSTATUS(rv)); 128 129 atomic_setbits_int(&p->p_flag, P_WEXIT); 130 131 pr = p->p_p; 132 133 /* single-threaded? */ 134 if (TAILQ_FIRST(&pr->ps_threads) == p && 135 TAILQ_NEXT(p, p_thr_link) == NULL) 136 flags = EXIT_NORMAL; 137 else { 138 /* nope, multi-threaded */ 139 if (flags == EXIT_NORMAL) 140 single_thread_set(p, SINGLE_EXIT, 0); 141 else if (flags == EXIT_THREAD) 142 single_thread_check(p, 0); 143 } 144 145 if (flags == EXIT_NORMAL) { 146 atomic_setbits_int(&pr->ps_flags, PS_EXITING); 147 pr->ps_mainproc->p_xstat = rv; 148 149 /* 150 * If parent is waiting for us to exit or exec, PS_PPWAIT 151 * is set; we wake up the parent early to avoid deadlock. 152 */ 153 if (pr->ps_flags & PS_PPWAIT) { 154 atomic_clearbits_int(&pr->ps_flags, PS_PPWAIT); 155 atomic_clearbits_int(&pr->ps_pptr->ps_flags, 156 PS_ISPWAIT); 157 wakeup(pr->ps_pptr); 158 } 159 } 160 161 /* unlink ourselves from the active threads */ 162 TAILQ_REMOVE(&pr->ps_threads, p, p_thr_link); 163 if ((p->p_flag & P_THREAD) == 0) { 164 /* main thread gotta wait because it has the pid, et al */ 165 while (! TAILQ_EMPTY(&pr->ps_threads)) 166 tsleep(&pr->ps_threads, PUSER, "thrdeath", 0); 167 if (pr->ps_flags & PS_PROFIL) 168 stopprofclock(pr); 169 } else if (TAILQ_EMPTY(&pr->ps_threads)) 170 wakeup(&pr->ps_threads); 171 172 rup = pr->ps_ru; 173 if (rup == NULL) { 174 rup = pool_get(&rusage_pool, PR_WAITOK | PR_ZERO); 175 176 if (pr->ps_ru == NULL) 177 pr->ps_ru = rup; 178 else { 179 pool_put(&rusage_pool, rup); 180 rup = pr->ps_ru; 181 } 182 } 183 p->p_siglist = 0; 184 185 /* 186 * Close open files and release open-file table. 187 */ 188 fdfree(p); 189 190 if ((p->p_flag & P_THREAD) == 0) { 191 timeout_del(&pr->ps_realit_to); 192 timeout_del(&pr->ps_virt_to); 193 timeout_del(&pr->ps_prof_to); 194 #ifdef SYSVSEM 195 semexit(pr); 196 #endif 197 if (SESS_LEADER(pr)) { 198 struct session *sp = pr->ps_session; 199 200 if (sp->s_ttyvp) { 201 /* 202 * Controlling process. 203 * Signal foreground pgrp, 204 * drain controlling terminal 205 * and revoke access to controlling terminal. 206 */ 207 if (sp->s_ttyp->t_session == sp) { 208 if (sp->s_ttyp->t_pgrp) 209 pgsignal(sp->s_ttyp->t_pgrp, 210 SIGHUP, 1); 211 (void) ttywait(sp->s_ttyp); 212 /* 213 * The tty could have been revoked 214 * if we blocked. 215 */ 216 if (sp->s_ttyvp) 217 VOP_REVOKE(sp->s_ttyvp, 218 REVOKEALL); 219 } 220 if (sp->s_ttyvp) 221 vrele(sp->s_ttyvp); 222 sp->s_ttyvp = NULL; 223 /* 224 * s_ttyp is not zero'd; we use this to 225 * indicate that the session once had a 226 * controlling terminal. (for logging and 227 * informational purposes) 228 */ 229 } 230 sp->s_leader = NULL; 231 } 232 fixjobc(pr, pr->ps_pgrp, 0); 233 234 #ifdef ACCOUNTING 235 (void)acct_process(p); 236 #endif 237 238 #ifdef KTRACE 239 /* release trace file */ 240 if (pr->ps_tracevp) 241 ktrcleartrace(pr); 242 #endif 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 process exit hook, call it now. 252 */ 253 if (p->p_emul->e_proc_exit) 254 (*p->p_emul->e_proc_exit)(p); 255 256 /* 257 * Remove proc from pidhash chain so looking it up won't 258 * work. Move it from allproc to zombproc, but do not yet 259 * wake up the reaper. We will put the proc on the 260 * deadproc list later (using the p_hash member), and 261 * wake up the reaper when we do. 262 */ 263 /* 264 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 265 */ 266 p->p_stat = SDEAD; 267 268 LIST_REMOVE(p, p_hash); 269 LIST_REMOVE(p, p_list); 270 LIST_INSERT_HEAD(&zombproc, p, p_list); 271 272 /* 273 * Give orphaned children to init(8). 274 */ 275 if ((p->p_flag & P_THREAD) == 0) { 276 qr = LIST_FIRST(&pr->ps_children); 277 if (qr) /* only need this if any child is S_ZOMB */ 278 wakeup(initproc->p_p); 279 for (; qr != 0; qr = nqr) { 280 nqr = LIST_NEXT(qr, ps_sibling); 281 proc_reparent(qr, initproc->p_p); 282 /* 283 * Traced processes are killed since their 284 * existence means someone is screwing up. 285 */ 286 if (qr->ps_flags & PS_TRACED && 287 !(qr->ps_flags & PS_EXITING)) { 288 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 289 /* 290 * If single threading is active, 291 * direct the signal to the active 292 * thread to avoid deadlock. 293 */ 294 if (qr->ps_single) 295 ptsignal(qr->ps_single, SIGKILL, 296 STHREAD); 297 else 298 prsignal(qr, SIGKILL); 299 } 300 } 301 } 302 303 304 /* add thread's accumulated rusage into the process's total */ 305 ruadd(rup, &p->p_ru); 306 307 /* 308 * clear %cpu usage during swap 309 */ 310 p->p_pctcpu = 0; 311 312 if ((p->p_flag & P_THREAD) == 0) { 313 /* 314 * Final thread has died, so add on our children's rusage 315 * and calculate the total times 316 */ 317 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 318 ruadd(rup, &pr->ps_cru); 319 320 /* notify interested parties of our demise and clean up */ 321 knote_processexit(pr); 322 323 /* 324 * Notify parent that we're gone. If we have P_NOZOMBIE 325 * or parent has the SAS_NOCLDWAIT flag set, notify process 1 326 * instead (and hope it will handle this situation). 327 */ 328 if ((p->p_flag & P_NOZOMBIE) || 329 (pr->ps_pptr->ps_mainproc->p_sigacts->ps_flags & 330 SAS_NOCLDWAIT)) { 331 struct process *ppr = pr->ps_pptr; 332 proc_reparent(pr, initproc->p_p); 333 /* 334 * If this was the last child of our parent, notify 335 * parent, so in case he was wait(2)ing, he will 336 * continue. 337 */ 338 if (LIST_EMPTY(&ppr->ps_children)) 339 wakeup(ppr); 340 } 341 } 342 343 /* 344 * Release the process's signal state. 345 */ 346 sigactsfree(p); 347 348 /* 349 * Other substructures are freed from reaper and wait(). 350 */ 351 352 /* 353 * Finally, call machine-dependent code to switch to a new 354 * context (possibly the idle context). Once we are no longer 355 * using the dead process's vmspace and stack, exit2() will be 356 * called to schedule those resources to be released by the 357 * reaper thread. 358 * 359 * Note that cpu_exit() will end with a call equivalent to 360 * cpu_switch(), finishing our execution (pun intended). 361 */ 362 uvmexp.swtch++; 363 cpu_exit(p); 364 panic("cpu_exit returned"); 365 } 366 367 /* 368 * Locking of this proclist is special; it's accessed in a 369 * critical section of process exit, and thus locking it can't 370 * modify interrupt state. We use a simple spin lock for this 371 * proclist. Processes on this proclist are also on zombproc; 372 * we use the p_hash member to linkup to deadproc. 373 */ 374 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 375 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 376 377 /* 378 * We are called from cpu_exit() once it is safe to schedule the 379 * dead process's resources to be freed. 380 * 381 * NOTE: One must be careful with locking in this routine. It's 382 * called from a critical section in machine-dependent code, so 383 * we should refrain from changing any interrupt state. 384 * 385 * We lock the deadproc list, place the proc on that list (using 386 * the p_hash member), and wake up the reaper. 387 */ 388 void 389 exit2(struct proc *p) 390 { 391 mtx_enter(&deadproc_mutex); 392 LIST_INSERT_HEAD(&deadproc, p, p_hash); 393 mtx_leave(&deadproc_mutex); 394 395 wakeup(&deadproc); 396 } 397 398 /* 399 * Process reaper. This is run by a kernel thread to free the resources 400 * of a dead process. Once the resources are free, the process becomes 401 * a zombie, and the parent is allowed to read the undead's status. 402 */ 403 void 404 reaper(void) 405 { 406 struct proc *p; 407 408 KERNEL_UNLOCK(); 409 410 SCHED_ASSERT_UNLOCKED(); 411 412 for (;;) { 413 mtx_enter(&deadproc_mutex); 414 while ((p = LIST_FIRST(&deadproc)) == NULL) 415 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 416 417 /* Remove us from the deadproc list. */ 418 LIST_REMOVE(p, p_hash); 419 mtx_leave(&deadproc_mutex); 420 421 KERNEL_LOCK(); 422 423 /* 424 * Free the VM resources we're still holding on to. 425 * We must do this from a valid thread because doing 426 * so may block. 427 */ 428 uvm_exit(p); 429 430 /* Process is now a true zombie. */ 431 if ((p->p_flag & P_NOZOMBIE) == 0) { 432 p->p_stat = SZOMB; 433 434 if (P_EXITSIG(p) != 0) 435 prsignal(p->p_p->ps_pptr, P_EXITSIG(p)); 436 /* Wake up the parent so it can get exit status. */ 437 wakeup(p->p_p->ps_pptr); 438 } else { 439 /* Noone will wait for us. Just zap the process now */ 440 proc_zap(p); 441 } 442 443 KERNEL_UNLOCK(); 444 } 445 } 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 int nfound; 457 struct process *pr; 458 struct proc *p; 459 int status, error; 460 461 if (SCARG(uap, pid) == 0) 462 SCARG(uap, pid) = -q->p_p->ps_pgid; 463 if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 464 return (EINVAL); 465 466 loop: 467 nfound = 0; 468 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 469 p = pr->ps_mainproc; 470 if ((p->p_flag & P_NOZOMBIE) || 471 (SCARG(uap, pid) != WAIT_ANY && 472 p->p_pid != SCARG(uap, pid) && 473 pr->ps_pgid != -SCARG(uap, pid))) 474 continue; 475 476 /* 477 * Wait for processes with p_exitsig != SIGCHLD processes only 478 * if WALTSIG is set; wait for processes with pexitsig == 479 * SIGCHLD only if WALTSIG is clear. 480 */ 481 if ((SCARG(uap, options) & WALTSIG) ? 482 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 483 continue; 484 485 nfound++; 486 if (p->p_stat == SZOMB) { 487 retval[0] = p->p_pid; 488 489 if (SCARG(uap, status)) { 490 status = p->p_xstat; /* convert to int */ 491 error = copyout(&status, 492 SCARG(uap, status), sizeof(status)); 493 if (error) 494 return (error); 495 } 496 if (SCARG(uap, rusage) && 497 (error = copyout(pr->ps_ru, 498 SCARG(uap, rusage), sizeof(struct rusage)))) 499 return (error); 500 proc_finish_wait(q, p); 501 return (0); 502 } 503 if (pr->ps_flags & PS_TRACED && 504 (pr->ps_flags & PS_WAITED) == 0 && pr->ps_single && 505 pr->ps_single->p_stat == SSTOP && 506 (pr->ps_single->p_flag & P_SUSPSINGLE) == 0) { 507 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 508 retval[0] = p->p_pid; 509 510 if (SCARG(uap, status)) { 511 status = W_STOPCODE(pr->ps_single->p_xstat); 512 error = copyout(&status, SCARG(uap, status), 513 sizeof(status)); 514 } else 515 error = 0; 516 return (error); 517 } 518 if (p->p_stat == SSTOP && 519 (pr->ps_flags & PS_WAITED) == 0 && 520 (p->p_flag & P_SUSPSINGLE) == 0 && 521 (pr->ps_flags & PS_TRACED || 522 SCARG(uap, options) & WUNTRACED)) { 523 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 524 retval[0] = p->p_pid; 525 526 if (SCARG(uap, status)) { 527 status = W_STOPCODE(p->p_xstat); 528 error = copyout(&status, SCARG(uap, status), 529 sizeof(status)); 530 } else 531 error = 0; 532 return (error); 533 } 534 if ((SCARG(uap, options) & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 535 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 536 retval[0] = p->p_pid; 537 538 if (SCARG(uap, status)) { 539 status = _WCONTINUED; 540 error = copyout(&status, SCARG(uap, status), 541 sizeof(status)); 542 } else 543 error = 0; 544 return (error); 545 } 546 } 547 if (nfound == 0) 548 return (ECHILD); 549 if (SCARG(uap, options) & WNOHANG) { 550 retval[0] = 0; 551 return (0); 552 } 553 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 554 return (error); 555 goto loop; 556 } 557 558 void 559 proc_finish_wait(struct proc *waiter, struct proc *p) 560 { 561 struct process *pr, *tr; 562 struct rusage *rup; 563 564 /* 565 * If we got the child via a ptrace 'attach', 566 * we need to give it back to the old parent. 567 */ 568 pr = p->p_p; 569 if ((p->p_flag & P_THREAD) == 0 && pr->ps_oppid && 570 (tr = prfind(pr->ps_oppid))) { 571 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 572 pr->ps_oppid = 0; 573 proc_reparent(pr, tr); 574 if (p->p_exitsig != 0) 575 prsignal(tr, p->p_exitsig); 576 wakeup(tr); 577 } else { 578 scheduler_wait_hook(waiter, p); 579 p->p_xstat = 0; 580 rup = &waiter->p_p->ps_cru; 581 ruadd(rup, pr->ps_ru); 582 proc_zap(p); 583 } 584 } 585 586 /* 587 * make process 'parent' the new parent of process 'child'. 588 */ 589 void 590 proc_reparent(struct process *child, struct process *parent) 591 { 592 593 if (child->ps_pptr == parent) 594 return; 595 596 if (parent == initproc->p_p) 597 child->ps_mainproc->p_exitsig = SIGCHLD; 598 599 LIST_REMOVE(child, ps_sibling); 600 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 601 child->ps_pptr = parent; 602 } 603 604 void 605 proc_zap(struct proc *p) 606 { 607 struct process *pr = p->p_p; 608 609 /* 610 * Finally finished with old proc entry. 611 * Unlink it from its process group and free it. 612 */ 613 if ((p->p_flag & P_THREAD) == 0) 614 leavepgrp(pr); 615 LIST_REMOVE(p, p_list); /* off zombproc */ 616 if ((p->p_flag & P_THREAD) == 0) { 617 LIST_REMOVE(pr, ps_sibling); 618 619 /* 620 * Decrement the count of procs running with this uid. 621 */ 622 (void)chgproccnt(p->p_cred->p_ruid, -1); 623 } 624 625 /* 626 * Release reference to text vnode 627 */ 628 if (p->p_textvp) 629 vrele(p->p_textvp); 630 631 /* 632 * Remove us from our process list, possibly killing the process 633 * in the process (pun intended). 634 */ 635 if (--pr->ps_refcnt == 0) { 636 if (pr->ps_ptstat != NULL) 637 free(pr->ps_ptstat, M_SUBPROC); 638 pool_put(&rusage_pool, pr->ps_ru); 639 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 640 limfree(pr->ps_limit); 641 crfree(pr->ps_cred->pc_ucred); 642 pool_put(&pcred_pool, pr->ps_cred); 643 pool_put(&process_pool, pr); 644 nprocesses--; 645 } 646 647 pool_put(&proc_pool, p); 648 nthreads--; 649 } 650