1 /* $OpenBSD: kern_exit.c,v 1.130 2014/01/20 03:23:42 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 #ifdef SYSVSEM 189 semexit(pr); 190 #endif 191 if (SESS_LEADER(pr)) { 192 struct session *sp = pr->ps_session; 193 194 if (sp->s_ttyvp) { 195 /* 196 * Controlling process. 197 * Signal foreground pgrp, 198 * drain controlling terminal 199 * and revoke access to controlling terminal. 200 */ 201 if (sp->s_ttyp->t_session == sp) { 202 if (sp->s_ttyp->t_pgrp) 203 pgsignal(sp->s_ttyp->t_pgrp, 204 SIGHUP, 1); 205 ttywait(sp->s_ttyp); 206 /* 207 * The tty could have been revoked 208 * if we blocked. 209 */ 210 if (sp->s_ttyvp) 211 VOP_REVOKE(sp->s_ttyvp, 212 REVOKEALL); 213 } 214 ovp = sp->s_ttyvp; 215 sp->s_ttyvp = NULL; 216 if (ovp) 217 vrele(ovp); 218 /* 219 * s_ttyp is not zero'd; we use this to 220 * indicate that the session once had a 221 * controlling terminal. (for logging and 222 * informational purposes) 223 */ 224 } 225 sp->s_leader = NULL; 226 } 227 fixjobc(pr, pr->ps_pgrp, 0); 228 229 #ifdef ACCOUNTING 230 acct_process(p); 231 #endif 232 233 #ifdef KTRACE 234 /* release trace file */ 235 if (pr->ps_tracevp) 236 ktrcleartrace(pr); 237 #endif 238 } 239 240 #if NSYSTRACE > 0 241 if (ISSET(p->p_flag, P_SYSTRACE)) 242 systrace_exit(p); 243 #endif 244 245 /* 246 * If emulation has process exit hook, call it now. 247 */ 248 if (p->p_emul->e_proc_exit) 249 (*p->p_emul->e_proc_exit)(p); 250 251 /* 252 * Remove proc from pidhash chain so looking it up won't 253 * work. Move it from allproc to zombproc, but do not yet 254 * wake up the reaper. We will put the proc on the 255 * deadproc list later (using the p_hash member), and 256 * wake up the reaper when we do. 257 */ 258 /* 259 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 260 */ 261 p->p_stat = SDEAD; 262 263 LIST_REMOVE(p, p_hash); 264 LIST_REMOVE(p, p_list); 265 LIST_INSERT_HEAD(&zombproc, p, p_list); 266 267 /* 268 * Give orphaned children to init(8). 269 */ 270 if ((p->p_flag & P_THREAD) == 0) { 271 qr = LIST_FIRST(&pr->ps_children); 272 if (qr) /* only need this if any child is S_ZOMB */ 273 wakeup(initproc->p_p); 274 for (; qr != 0; qr = nqr) { 275 nqr = LIST_NEXT(qr, ps_sibling); 276 proc_reparent(qr, initproc->p_p); 277 /* 278 * Traced processes are killed since their 279 * existence means someone is screwing up. 280 */ 281 if (qr->ps_flags & PS_TRACED && 282 !(qr->ps_flags & PS_EXITING)) { 283 atomic_clearbits_int(&qr->ps_flags, PS_TRACED); 284 /* 285 * If single threading is active, 286 * direct the signal to the active 287 * thread to avoid deadlock. 288 */ 289 if (qr->ps_single) 290 ptsignal(qr->ps_single, SIGKILL, 291 STHREAD); 292 else 293 prsignal(qr, SIGKILL); 294 } 295 } 296 } 297 298 299 /* add thread's accumulated rusage into the process's total */ 300 ruadd(rup, &p->p_ru); 301 302 /* 303 * clear %cpu usage during swap 304 */ 305 p->p_pctcpu = 0; 306 307 if ((p->p_flag & P_THREAD) == 0) { 308 /* 309 * Final thread has died, so add on our children's rusage 310 * and calculate the total times 311 */ 312 calcru(&pr->ps_tu, &rup->ru_utime, &rup->ru_stime, NULL); 313 ruadd(rup, &pr->ps_cru); 314 315 /* notify interested parties of our demise and clean up */ 316 knote_processexit(pr); 317 318 /* 319 * Notify parent that we're gone. If we have P_NOZOMBIE 320 * or parent has the SAS_NOCLDWAIT flag set, notify process 1 321 * instead (and hope it will handle this situation). 322 */ 323 if ((p->p_flag & P_NOZOMBIE) || 324 (pr->ps_pptr->ps_mainproc->p_sigacts->ps_flags & 325 SAS_NOCLDWAIT)) { 326 struct process *ppr = pr->ps_pptr; 327 proc_reparent(pr, initproc->p_p); 328 329 /* 330 * Notify parent, so in case he was wait(2)ing or 331 * executing waitpid(2) with our pid, he will 332 * continue. 333 */ 334 wakeup(ppr); 335 } 336 } 337 338 /* 339 * Release the process's signal state. 340 */ 341 sigactsfree(p); 342 343 /* 344 * Other substructures are freed from reaper and wait(). 345 */ 346 347 /* 348 * Finally, call machine-dependent code to switch to a new 349 * context (possibly the idle context). Once we are no longer 350 * using the dead process's vmspace and stack, exit2() will be 351 * called to schedule those resources to be released by the 352 * reaper thread. 353 * 354 * Note that cpu_exit() will end with a call equivalent to 355 * cpu_switch(), finishing our execution (pun intended). 356 */ 357 uvmexp.swtch++; 358 cpu_exit(p); 359 panic("cpu_exit returned"); 360 } 361 362 /* 363 * Locking of this proclist is special; it's accessed in a 364 * critical section of process exit, and thus locking it can't 365 * modify interrupt state. We use a simple spin lock for this 366 * proclist. Processes on this proclist are also on zombproc; 367 * we use the p_hash member to linkup to deadproc. 368 */ 369 struct mutex deadproc_mutex = MUTEX_INITIALIZER(IPL_NONE); 370 struct proclist deadproc = LIST_HEAD_INITIALIZER(deadproc); 371 372 /* 373 * We are called from cpu_exit() once it is safe to schedule the 374 * dead process's resources to be freed. 375 * 376 * NOTE: One must be careful with locking in this routine. It's 377 * called from a critical section in machine-dependent code, so 378 * we should refrain from changing any interrupt state. 379 * 380 * We lock the deadproc list, place the proc on that list (using 381 * the p_hash member), and wake up the reaper. 382 */ 383 void 384 exit2(struct proc *p) 385 { 386 mtx_enter(&deadproc_mutex); 387 LIST_INSERT_HEAD(&deadproc, p, p_hash); 388 mtx_leave(&deadproc_mutex); 389 390 wakeup(&deadproc); 391 } 392 393 /* 394 * Process reaper. This is run by a kernel thread to free the resources 395 * of a dead process. Once the resources are free, the process becomes 396 * a zombie, and the parent is allowed to read the undead's status. 397 */ 398 void 399 reaper(void) 400 { 401 struct proc *p; 402 403 KERNEL_UNLOCK(); 404 405 SCHED_ASSERT_UNLOCKED(); 406 407 for (;;) { 408 mtx_enter(&deadproc_mutex); 409 while ((p = LIST_FIRST(&deadproc)) == NULL) 410 msleep(&deadproc, &deadproc_mutex, PVM, "reaper", 0); 411 412 /* Remove us from the deadproc list. */ 413 LIST_REMOVE(p, p_hash); 414 mtx_leave(&deadproc_mutex); 415 416 KERNEL_LOCK(); 417 418 /* 419 * Free the VM resources we're still holding on to. 420 * We must do this from a valid thread because doing 421 * so may block. 422 */ 423 uvm_exit(p); 424 425 /* Process is now a true zombie. */ 426 if ((p->p_flag & P_NOZOMBIE) == 0) { 427 p->p_stat = SZOMB; 428 429 if (P_EXITSIG(p) != 0) 430 prsignal(p->p_p->ps_pptr, P_EXITSIG(p)); 431 /* Wake up the parent so it can get exit status. */ 432 wakeup(p->p_p->ps_pptr); 433 } else { 434 /* Noone will wait for us. Just zap the process now */ 435 proc_zap(p); 436 } 437 438 KERNEL_UNLOCK(); 439 } 440 } 441 442 int 443 sys_wait4(struct proc *q, void *v, register_t *retval) 444 { 445 struct sys_wait4_args /* { 446 syscallarg(pid_t) pid; 447 syscallarg(int *) status; 448 syscallarg(int) options; 449 syscallarg(struct rusage *) rusage; 450 } */ *uap = v; 451 struct rusage ru; 452 int status, error; 453 454 error = dowait4(q, SCARG(uap, pid), 455 SCARG(uap, status) ? &status : NULL, 456 SCARG(uap, options), SCARG(uap, rusage) ? &ru : NULL, retval); 457 if (error == 0 && SCARG(uap, status)) { 458 error = copyout(&status, SCARG(uap, status), sizeof(status)); 459 } 460 if (error == 0 && SCARG(uap, rusage)) { 461 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 462 } 463 return (error); 464 } 465 466 int 467 dowait4(struct proc *q, pid_t pid, int *statusp, int options, 468 struct rusage *rusage, register_t *retval) 469 { 470 int nfound; 471 struct process *pr; 472 struct proc *p; 473 int error; 474 475 if (pid == 0) 476 pid = -q->p_p->ps_pgid; 477 if (options &~ (WUNTRACED|WNOHANG|WALTSIG|WCONTINUED)) 478 return (EINVAL); 479 480 loop: 481 nfound = 0; 482 LIST_FOREACH(pr, &q->p_p->ps_children, ps_sibling) { 483 p = pr->ps_mainproc; 484 if ((p->p_flag & P_NOZOMBIE) || 485 (pid != WAIT_ANY && 486 p->p_pid != pid && 487 pr->ps_pgid != -pid)) 488 continue; 489 490 /* 491 * Wait for processes with p_exitsig != SIGCHLD processes only 492 * if WALTSIG is set; wait for processes with pexitsig == 493 * SIGCHLD only if WALTSIG is clear. 494 */ 495 if ((options & WALTSIG) ? 496 (p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD)) 497 continue; 498 499 nfound++; 500 if (p->p_stat == SZOMB) { 501 retval[0] = p->p_pid; 502 503 if (statusp != NULL) 504 *statusp = p->p_xstat; /* convert to int */ 505 if (rusage != NULL) 506 memcpy(rusage, pr->ps_ru, sizeof(*rusage)); 507 proc_finish_wait(q, p); 508 return (0); 509 } 510 if (pr->ps_flags & PS_TRACED && 511 (pr->ps_flags & PS_WAITED) == 0 && pr->ps_single && 512 pr->ps_single->p_stat == SSTOP && 513 (pr->ps_single->p_flag & P_SUSPSINGLE) == 0) { 514 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 515 retval[0] = p->p_pid; 516 517 if (statusp != NULL) 518 *statusp = W_STOPCODE(pr->ps_single->p_xstat); 519 return (0); 520 } 521 if (p->p_stat == SSTOP && 522 (pr->ps_flags & PS_WAITED) == 0 && 523 (p->p_flag & P_SUSPSINGLE) == 0 && 524 (pr->ps_flags & PS_TRACED || 525 options & WUNTRACED)) { 526 atomic_setbits_int(&pr->ps_flags, PS_WAITED); 527 retval[0] = p->p_pid; 528 529 if (statusp != NULL) 530 *statusp = W_STOPCODE(p->p_xstat); 531 return (0); 532 } 533 if ((options & WCONTINUED) && (p->p_flag & P_CONTINUED)) { 534 atomic_clearbits_int(&p->p_flag, P_CONTINUED); 535 retval[0] = p->p_pid; 536 537 if (statusp != NULL) 538 *statusp = _WCONTINUED; 539 return (0); 540 } 541 } 542 if (nfound == 0) 543 return (ECHILD); 544 if (options & WNOHANG) { 545 retval[0] = 0; 546 return (0); 547 } 548 if ((error = tsleep(q->p_p, PWAIT | PCATCH, "wait", 0)) != 0) 549 return (error); 550 goto loop; 551 } 552 553 void 554 proc_finish_wait(struct proc *waiter, struct proc *p) 555 { 556 struct process *pr, *tr; 557 struct rusage *rup; 558 559 /* 560 * If we got the child via a ptrace 'attach', 561 * we need to give it back to the old parent. 562 */ 563 pr = p->p_p; 564 if ((p->p_flag & P_THREAD) == 0 && pr->ps_oppid && 565 (tr = prfind(pr->ps_oppid))) { 566 atomic_clearbits_int(&pr->ps_flags, PS_TRACED); 567 pr->ps_oppid = 0; 568 proc_reparent(pr, tr); 569 if (p->p_exitsig != 0) 570 prsignal(tr, p->p_exitsig); 571 wakeup(tr); 572 } else { 573 scheduler_wait_hook(waiter, p); 574 p->p_xstat = 0; 575 rup = &waiter->p_p->ps_cru; 576 ruadd(rup, pr->ps_ru); 577 proc_zap(p); 578 } 579 } 580 581 /* 582 * make process 'parent' the new parent of process 'child'. 583 */ 584 void 585 proc_reparent(struct process *child, struct process *parent) 586 { 587 588 if (child->ps_pptr == parent) 589 return; 590 591 if (parent == initproc->p_p) 592 child->ps_mainproc->p_exitsig = SIGCHLD; 593 594 LIST_REMOVE(child, ps_sibling); 595 LIST_INSERT_HEAD(&parent->ps_children, child, ps_sibling); 596 child->ps_pptr = parent; 597 } 598 599 void 600 proc_zap(struct proc *p) 601 { 602 struct process *pr = p->p_p; 603 struct vnode *otvp; 604 605 /* 606 * Finally finished with old proc entry. 607 * Unlink it from its process group and free it. 608 */ 609 if ((p->p_flag & P_THREAD) == 0) 610 leavepgrp(pr); 611 LIST_REMOVE(p, p_list); /* off zombproc */ 612 if ((p->p_flag & P_THREAD) == 0) { 613 LIST_REMOVE(pr, ps_sibling); 614 615 /* 616 * Decrement the count of procs running with this uid. 617 */ 618 (void)chgproccnt(p->p_cred->p_ruid, -1); 619 620 /* 621 * Release reference to text vnode 622 */ 623 otvp = pr->ps_textvp; 624 pr->ps_textvp = NULL; 625 if (otvp) 626 vrele(otvp); 627 } 628 629 /* 630 * Remove us from our process list, possibly killing the process 631 * in the process (pun intended). 632 */ 633 if (--pr->ps_refcnt == 0) { 634 if (pr->ps_ptstat != NULL) 635 free(pr->ps_ptstat, M_SUBPROC); 636 pool_put(&rusage_pool, pr->ps_ru); 637 KASSERT(TAILQ_EMPTY(&pr->ps_threads)); 638 limfree(pr->ps_limit); 639 crfree(pr->ps_cred->pc_ucred); 640 pool_put(&pcred_pool, pr->ps_cred); 641 pool_put(&process_pool, pr); 642 nprocesses--; 643 } 644 645 freepid(p->p_pid); 646 pool_put(&proc_pool, p); 647 nthreads--; 648 } 649