1 /* $NetBSD: kern_exit.c,v 1.241 2012/08/05 14:53:25 riastradh Exp $ */ 2 3 /*- 4 * Copyright (c) 1998, 1999, 2006, 2007, 2008 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, 9 * NASA Ames Research Center, and by Andrew Doran. 10 * 11 * Redistribution and use in source and binary forms, with or without 12 * modification, are permitted provided that the following conditions 13 * are met: 14 * 1. Redistributions of source code must retain the above copyright 15 * notice, this list of conditions and the following disclaimer. 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in the 18 * documentation and/or other materials provided with the distribution. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 21 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 22 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 23 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 24 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 25 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 26 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 27 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 28 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 29 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 30 * POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 /* 34 * Copyright (c) 1982, 1986, 1989, 1991, 1993 35 * The Regents of the University of California. All rights reserved. 36 * (c) UNIX System Laboratories, Inc. 37 * All or some portions of this file are derived from material licensed 38 * to the University of California by American Telephone and Telegraph 39 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 40 * the permission of UNIX System Laboratories, Inc. 41 * 42 * Redistribution and use in source and binary forms, with or without 43 * modification, are permitted provided that the following conditions 44 * are met: 45 * 1. Redistributions of source code must retain the above copyright 46 * notice, this list of conditions and the following disclaimer. 47 * 2. Redistributions in binary form must reproduce the above copyright 48 * notice, this list of conditions and the following disclaimer in the 49 * documentation and/or other materials provided with the distribution. 50 * 3. Neither the name of the University nor the names of its contributors 51 * may be used to endorse or promote products derived from this software 52 * without specific prior written permission. 53 * 54 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 55 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 56 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 57 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 58 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 59 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 60 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 61 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 62 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 63 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 64 * SUCH DAMAGE. 65 * 66 * @(#)kern_exit.c 8.10 (Berkeley) 2/23/95 67 */ 68 69 #include <sys/cdefs.h> 70 __KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.241 2012/08/05 14:53:25 riastradh Exp $"); 71 72 #include "opt_ktrace.h" 73 #include "opt_perfctrs.h" 74 #include "opt_sysv.h" 75 76 #include <sys/param.h> 77 #include <sys/systm.h> 78 #include <sys/ioctl.h> 79 #include <sys/tty.h> 80 #include <sys/time.h> 81 #include <sys/resource.h> 82 #include <sys/kernel.h> 83 #include <sys/proc.h> 84 #include <sys/buf.h> 85 #include <sys/wait.h> 86 #include <sys/file.h> 87 #include <sys/vnode.h> 88 #include <sys/syslog.h> 89 #include <sys/pool.h> 90 #include <sys/uidinfo.h> 91 #if defined(PERFCTRS) 92 #include <sys/pmc.h> 93 #endif 94 #include <sys/ptrace.h> 95 #include <sys/acct.h> 96 #include <sys/filedesc.h> 97 #include <sys/ras.h> 98 #include <sys/signalvar.h> 99 #include <sys/sched.h> 100 #include <sys/mount.h> 101 #include <sys/syscallargs.h> 102 #include <sys/kauth.h> 103 #include <sys/sleepq.h> 104 #include <sys/lockdebug.h> 105 #include <sys/ktrace.h> 106 #include <sys/cpu.h> 107 #include <sys/lwpctl.h> 108 #include <sys/atomic.h> 109 #include <sys/sdt.h> 110 111 #include <uvm/uvm_extern.h> 112 113 #ifdef DEBUG_EXIT 114 int debug_exit = 0; 115 #define DPRINTF(x) if (debug_exit) printf x 116 #else 117 #define DPRINTF(x) 118 #endif 119 120 static int find_stopped_child(struct proc *, pid_t, int, struct proc **, int *); 121 static void proc_free(struct proc *, struct rusage *); 122 123 /* 124 * DTrace SDT provider definitions 125 */ 126 SDT_PROBE_DEFINE(proc,,,exit, 127 "int", NULL, /* reason */ 128 NULL, NULL, NULL, NULL, 129 NULL, NULL, NULL, NULL); 130 /* 131 * Fill in the appropriate signal information, and signal the parent. 132 */ 133 /* XXX noclone works around a gcc 4.5 bug on arm */ 134 static void __noclone 135 exit_psignal(struct proc *p, struct proc *pp, ksiginfo_t *ksi) 136 { 137 138 KSI_INIT(ksi); 139 if ((ksi->ksi_signo = P_EXITSIG(p)) == SIGCHLD) { 140 if (WIFSIGNALED(p->p_xstat)) { 141 if (WCOREDUMP(p->p_xstat)) 142 ksi->ksi_code = CLD_DUMPED; 143 else 144 ksi->ksi_code = CLD_KILLED; 145 } else { 146 ksi->ksi_code = CLD_EXITED; 147 } 148 } 149 /* 150 * We fill those in, even for non-SIGCHLD. 151 * It's safe to access p->p_cred unlocked here. 152 */ 153 ksi->ksi_pid = p->p_pid; 154 ksi->ksi_uid = kauth_cred_geteuid(p->p_cred); 155 ksi->ksi_status = p->p_xstat; 156 /* XXX: is this still valid? */ 157 ksi->ksi_utime = p->p_stats->p_ru.ru_utime.tv_sec; 158 ksi->ksi_stime = p->p_stats->p_ru.ru_stime.tv_sec; 159 } 160 161 /* 162 * exit -- 163 * Death of process. 164 */ 165 int 166 sys_exit(struct lwp *l, const struct sys_exit_args *uap, register_t *retval) 167 { 168 /* { 169 syscallarg(int) rval; 170 } */ 171 struct proc *p = l->l_proc; 172 173 /* Don't call exit1() multiple times in the same process. */ 174 mutex_enter(p->p_lock); 175 if (p->p_sflag & PS_WEXIT) { 176 mutex_exit(p->p_lock); 177 lwp_exit(l); 178 } 179 180 /* exit1() will release the mutex. */ 181 exit1(l, W_EXITCODE(SCARG(uap, rval), 0)); 182 /* NOTREACHED */ 183 return (0); 184 } 185 186 /* 187 * Exit: deallocate address space and other resources, change proc state 188 * to zombie, and unlink proc from allproc and parent's lists. Save exit 189 * status and rusage for wait(). Check for child processes and orphan them. 190 * 191 * Must be called with p->p_lock held. Does not return. 192 */ 193 void 194 exit1(struct lwp *l, int rv) 195 { 196 struct proc *p, *child, *next_child, *old_parent, *new_parent; 197 struct pgrp *pgrp; 198 ksiginfo_t ksi; 199 ksiginfoq_t kq; 200 int wakeinit; 201 202 p = l->l_proc; 203 204 KASSERT(mutex_owned(p->p_lock)); 205 KASSERT(p->p_vmspace != NULL); 206 207 if (__predict_false(p == initproc)) { 208 panic("init died (signal %d, exit %d)", 209 WTERMSIG(rv), WEXITSTATUS(rv)); 210 } 211 212 p->p_sflag |= PS_WEXIT; 213 214 /* 215 * Force all other LWPs to exit before we do. Only then can we 216 * begin to tear down the rest of the process state. 217 */ 218 if (p->p_nlwps > 1) { 219 exit_lwps(l); 220 } 221 222 ksiginfo_queue_init(&kq); 223 224 /* 225 * If we have been asked to stop on exit, do so now. 226 */ 227 if (__predict_false(p->p_sflag & PS_STOPEXIT)) { 228 KERNEL_UNLOCK_ALL(l, &l->l_biglocks); 229 sigclearall(p, &contsigmask, &kq); 230 p->p_waited = 0; 231 membar_producer(); 232 p->p_stat = SSTOP; 233 lwp_lock(l); 234 p->p_nrlwps--; 235 l->l_stat = LSSTOP; 236 lwp_unlock(l); 237 mutex_exit(p->p_lock); 238 lwp_lock(l); 239 mi_switch(l); 240 KERNEL_LOCK(l->l_biglocks, l); 241 mutex_enter(p->p_lock); 242 } 243 244 /* 245 * Bin any remaining signals and mark the process as dying so it will 246 * not be found for, e.g. signals. 247 */ 248 sigfillset(&p->p_sigctx.ps_sigignore); 249 sigclearall(p, NULL, &kq); 250 p->p_stat = SDYING; 251 mutex_exit(p->p_lock); 252 ksiginfo_queue_drain(&kq); 253 254 /* Destroy any lwpctl info. */ 255 if (p->p_lwpctl != NULL) 256 lwp_ctl_exit(); 257 258 /* 259 * Drain all remaining references that procfs, ptrace and others may 260 * have on the process. 261 */ 262 rw_enter(&p->p_reflock, RW_WRITER); 263 264 DPRINTF(("exit1: %d.%d exiting.\n", p->p_pid, l->l_lid)); 265 266 timers_free(p, TIMERS_ALL); 267 #if defined(__HAVE_RAS) 268 ras_purgeall(); 269 #endif 270 271 /* 272 * Close open files, release open-file table and free signal 273 * actions. This may block! 274 */ 275 fd_free(); 276 cwdfree(p->p_cwdi); 277 p->p_cwdi = NULL; 278 doexithooks(p); 279 sigactsfree(p->p_sigacts); 280 281 /* 282 * Write out accounting data. 283 */ 284 (void)acct_process(l); 285 286 #ifdef KTRACE 287 /* 288 * Release trace file. 289 */ 290 if (p->p_tracep != NULL) { 291 mutex_enter(&ktrace_lock); 292 ktrderef(p); 293 mutex_exit(&ktrace_lock); 294 } 295 #endif 296 297 /* 298 * If emulation has process exit hook, call it now. 299 * Set the exit status now so that the exit hook has 300 * an opportunity to tweak it (COMPAT_LINUX requires 301 * this for thread group emulation) 302 */ 303 p->p_xstat = rv; 304 if (p->p_emul->e_proc_exit) 305 (*p->p_emul->e_proc_exit)(p); 306 307 /* 308 * Free the VM resources we're still holding on to. 309 * We must do this from a valid thread because doing 310 * so may block. This frees vmspace, which we don't 311 * need anymore. The only remaining lwp is the one 312 * we run at this moment, nothing runs in userland 313 * anymore. 314 */ 315 uvm_proc_exit(p); 316 317 /* 318 * Stop profiling. 319 */ 320 if (__predict_false((p->p_stflag & PST_PROFIL) != 0)) { 321 mutex_spin_enter(&p->p_stmutex); 322 stopprofclock(p); 323 mutex_spin_exit(&p->p_stmutex); 324 } 325 326 /* 327 * If parent is waiting for us to exit or exec, PL_PPWAIT is set; we 328 * wake up the parent early to avoid deadlock. We can do this once 329 * the VM resources are released. 330 */ 331 mutex_enter(proc_lock); 332 if (p->p_lflag & PL_PPWAIT) { 333 #if 0 334 lwp_t *lp; 335 336 l->l_lwpctl = NULL; /* was on loan from blocked parent */ 337 p->p_lflag &= ~PL_PPWAIT; 338 339 lp = p->p_vforklwp; 340 p->p_vforklwp = NULL; 341 lp->l_pflag &= ~LP_VFORKWAIT; /* XXX */ 342 cv_broadcast(&lp->l_waitcv); 343 #else 344 l->l_lwpctl = NULL; /* was on loan from blocked parent */ 345 p->p_lflag &= ~PL_PPWAIT; 346 cv_broadcast(&p->p_pptr->p_waitcv); 347 #endif 348 } 349 350 if (SESS_LEADER(p)) { 351 struct vnode *vprele = NULL, *vprevoke = NULL; 352 struct session *sp = p->p_session; 353 struct tty *tp; 354 355 if (sp->s_ttyvp) { 356 /* 357 * Controlling process. 358 * Signal foreground pgrp, 359 * drain controlling terminal 360 * and revoke access to controlling terminal. 361 */ 362 tp = sp->s_ttyp; 363 mutex_spin_enter(&tty_lock); 364 if (tp->t_session == sp) { 365 /* we can't guarantee the revoke will do this */ 366 pgrp = tp->t_pgrp; 367 tp->t_pgrp = NULL; 368 tp->t_session = NULL; 369 mutex_spin_exit(&tty_lock); 370 if (pgrp != NULL) { 371 pgsignal(pgrp, SIGHUP, 1); 372 } 373 mutex_exit(proc_lock); 374 (void) ttywait(tp); 375 mutex_enter(proc_lock); 376 377 /* The tty could have been revoked. */ 378 vprevoke = sp->s_ttyvp; 379 } else 380 mutex_spin_exit(&tty_lock); 381 vprele = sp->s_ttyvp; 382 sp->s_ttyvp = NULL; 383 /* 384 * s_ttyp is not zero'd; we use this to indicate 385 * that the session once had a controlling terminal. 386 * (for logging and informational purposes) 387 */ 388 } 389 sp->s_leader = NULL; 390 391 if (vprevoke != NULL || vprele != NULL) { 392 if (vprevoke != NULL) { 393 /* Releases proc_lock. */ 394 proc_sessrele(sp); 395 VOP_REVOKE(vprevoke, REVOKEALL); 396 } else 397 mutex_exit(proc_lock); 398 if (vprele != NULL) 399 vrele(vprele); 400 mutex_enter(proc_lock); 401 } 402 } 403 fixjobc(p, p->p_pgrp, 0); 404 405 /* 406 * Finalize the last LWP's specificdata, as well as the 407 * specificdata for the proc itself. 408 */ 409 lwp_finispecific(l); 410 proc_finispecific(p); 411 412 /* 413 * Notify interested parties of our demise. 414 */ 415 KNOTE(&p->p_klist, NOTE_EXIT); 416 417 SDT_PROBE(proc,,,exit, 418 (WCOREDUMP(rv) ? CLD_DUMPED : 419 (WIFSIGNALED(rv) ? CLD_KILLED : CLD_EXITED)), 420 0,0,0,0); 421 422 #if PERFCTRS 423 /* 424 * Save final PMC information in parent process & clean up. 425 */ 426 if (PMC_ENABLED(p)) { 427 pmc_save_context(p); 428 pmc_accumulate(p->p_pptr, p); 429 pmc_process_exit(p); 430 } 431 #endif 432 433 /* 434 * Reset p_opptr pointer of all former children which got 435 * traced by another process and were reparented. We reset 436 * it to NULL here; the trace detach code then reparents 437 * the child to initproc. We only check allproc list, since 438 * eventual former children on zombproc list won't reference 439 * p_opptr anymore. 440 */ 441 if (__predict_false(p->p_slflag & PSL_CHTRACED)) { 442 struct proc *q; 443 PROCLIST_FOREACH(q, &allproc) { 444 if (q->p_opptr == p) 445 q->p_opptr = NULL; 446 } 447 } 448 449 /* 450 * Give orphaned children to init(8). 451 */ 452 child = LIST_FIRST(&p->p_children); 453 wakeinit = (child != NULL); 454 for (; child != NULL; child = next_child) { 455 next_child = LIST_NEXT(child, p_sibling); 456 457 /* 458 * Traced processes are killed since their existence 459 * means someone is screwing up. Since we reset the 460 * trace flags, the logic in sys_wait4() would not be 461 * triggered to reparent the process to its 462 * original parent, so we must do this here. 463 */ 464 if (__predict_false(child->p_slflag & PSL_TRACED)) { 465 mutex_enter(p->p_lock); 466 child->p_slflag &= 467 ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 468 mutex_exit(p->p_lock); 469 if (child->p_opptr != child->p_pptr) { 470 struct proc *t = child->p_opptr; 471 proc_reparent(child, t ? t : initproc); 472 child->p_opptr = NULL; 473 } else 474 proc_reparent(child, initproc); 475 killproc(child, "orphaned traced process"); 476 } else 477 proc_reparent(child, initproc); 478 } 479 480 /* 481 * Move proc from allproc to zombproc, it's now nearly ready to be 482 * collected by parent. 483 */ 484 LIST_REMOVE(l, l_list); 485 LIST_REMOVE(p, p_list); 486 LIST_INSERT_HEAD(&zombproc, p, p_list); 487 488 /* 489 * Mark the process as dead. We must do this before we signal 490 * the parent. 491 */ 492 p->p_stat = SDEAD; 493 494 /* Put in front of parent's sibling list for parent to collect it */ 495 old_parent = p->p_pptr; 496 old_parent->p_nstopchild++; 497 if (LIST_FIRST(&old_parent->p_children) != p) { 498 /* Put child where it can be found quickly */ 499 LIST_REMOVE(p, p_sibling); 500 LIST_INSERT_HEAD(&old_parent->p_children, p, p_sibling); 501 } 502 503 /* 504 * Notify parent that we're gone. If parent has the P_NOCLDWAIT 505 * flag set, notify init instead (and hope it will handle 506 * this situation). 507 */ 508 if (old_parent->p_flag & (PK_NOCLDWAIT|PK_CLDSIGIGN)) { 509 proc_reparent(p, initproc); 510 wakeinit = 1; 511 512 /* 513 * If this was the last child of our parent, notify 514 * parent, so in case he was wait(2)ing, he will 515 * continue. 516 */ 517 if (LIST_FIRST(&old_parent->p_children) == NULL) 518 cv_broadcast(&old_parent->p_waitcv); 519 } 520 521 /* Reload parent pointer, since p may have been reparented above */ 522 new_parent = p->p_pptr; 523 524 if (__predict_false((p->p_slflag & PSL_FSTRACE) == 0 && 525 p->p_exitsig != 0)) { 526 exit_psignal(p, new_parent, &ksi); 527 kpsignal(new_parent, &ksi, NULL); 528 } 529 530 /* Calculate the final rusage info. */ 531 calcru(p, &p->p_stats->p_ru.ru_utime, &p->p_stats->p_ru.ru_stime, 532 NULL, NULL); 533 534 if (wakeinit) 535 cv_broadcast(&initproc->p_waitcv); 536 537 callout_destroy(&l->l_timeout_ch); 538 539 /* 540 * Release any PCU resources before becoming a zombie. 541 */ 542 pcu_discard_all(l); 543 544 /* 545 * Remaining lwp resources will be freed in lwp_exit2() once we've 546 * switch to idle context; at that point, we will be marked as a 547 * full blown zombie. 548 */ 549 mutex_enter(p->p_lock); 550 lwp_drainrefs(l); 551 lwp_lock(l); 552 l->l_prflag &= ~LPR_DETACHED; 553 l->l_stat = LSZOMB; 554 lwp_unlock(l); 555 KASSERT(curlwp == l); 556 KASSERT(p->p_nrlwps == 1); 557 KASSERT(p->p_nlwps == 1); 558 p->p_stat = SZOMB; 559 p->p_nrlwps--; 560 p->p_nzlwps++; 561 p->p_ndlwps = 0; 562 mutex_exit(p->p_lock); 563 564 /* 565 * Signal the parent to collect us, and drop the proclist lock. 566 * Drop debugger/procfs lock; no new references can be gained. 567 */ 568 cv_broadcast(&p->p_pptr->p_waitcv); 569 rw_exit(&p->p_reflock); 570 mutex_exit(proc_lock); 571 572 /* Verify that we hold no locks other than the kernel lock. */ 573 LOCKDEBUG_BARRIER(&kernel_lock, 0); 574 575 /* 576 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 577 */ 578 579 /* 580 * Give machine-dependent code a chance to free any MD LWP 581 * resources. This must be done before uvm_lwp_exit(), in 582 * case these resources are in the PCB. 583 */ 584 cpu_lwp_free(l, 1); 585 586 pmap_deactivate(l); 587 588 /* This process no longer needs to hold the kernel lock. */ 589 #ifdef notyet 590 /* XXXSMP hold in lwp_userret() */ 591 KERNEL_UNLOCK_LAST(l); 592 #else 593 KERNEL_UNLOCK_ALL(l, NULL); 594 #endif 595 596 lwp_exit_switchaway(l); 597 } 598 599 void 600 exit_lwps(struct lwp *l) 601 { 602 struct proc *p; 603 struct lwp *l2; 604 int error; 605 lwpid_t waited; 606 int nlocks; 607 608 KERNEL_UNLOCK_ALL(l, &nlocks); 609 610 p = l->l_proc; 611 KASSERT(mutex_owned(p->p_lock)); 612 retry: 613 /* 614 * Interrupt LWPs in interruptable sleep, unsuspend suspended 615 * LWPs and then wait for everyone else to finish. 616 */ 617 LIST_FOREACH(l2, &p->p_lwps, l_sibling) { 618 if (l2 == l) 619 continue; 620 lwp_lock(l2); 621 l2->l_flag |= LW_WEXIT; 622 if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) || 623 l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) { 624 /* setrunnable() will release the lock. */ 625 setrunnable(l2); 626 DPRINTF(("exit_lwps: Made %d.%d runnable\n", 627 p->p_pid, l2->l_lid)); 628 continue; 629 } 630 lwp_unlock(l2); 631 } 632 while (p->p_nlwps > 1) { 633 DPRINTF(("exit_lwps: waiting for %d LWPs (%d zombies)\n", 634 p->p_nlwps, p->p_nzlwps)); 635 error = lwp_wait1(l, 0, &waited, LWPWAIT_EXITCONTROL); 636 if (p->p_nlwps == 1) 637 break; 638 if (error == EDEADLK) { 639 /* 640 * LWPs can get suspended/slept behind us. 641 * (eg. sa_setwoken) 642 * kick them again and retry. 643 */ 644 goto retry; 645 } 646 if (error) 647 panic("exit_lwps: lwp_wait1 failed with error %d", 648 error); 649 DPRINTF(("exit_lwps: Got LWP %d from lwp_wait1()\n", waited)); 650 } 651 652 KERNEL_LOCK(nlocks, l); 653 KASSERT(p->p_nlwps == 1); 654 } 655 656 int 657 do_sys_wait(int *pid, int *status, int options, struct rusage *ru) 658 { 659 proc_t *child; 660 int error; 661 662 if (ru != NULL) { 663 memset(ru, 0, sizeof(*ru)); 664 } 665 mutex_enter(proc_lock); 666 error = find_stopped_child(curproc, *pid, options, &child, status); 667 if (child == NULL) { 668 mutex_exit(proc_lock); 669 *pid = 0; 670 return error; 671 } 672 *pid = child->p_pid; 673 674 if (child->p_stat == SZOMB) { 675 /* proc_free() will release the proc_lock. */ 676 if (options & WNOWAIT) { 677 mutex_exit(proc_lock); 678 } else { 679 proc_free(child, ru); 680 } 681 } else { 682 /* Child state must have been SSTOP. */ 683 mutex_exit(proc_lock); 684 *status = W_STOPCODE(*status); 685 } 686 return 0; 687 } 688 689 int 690 sys___wait450(struct lwp *l, const struct sys___wait450_args *uap, 691 register_t *retval) 692 { 693 /* { 694 syscallarg(int) pid; 695 syscallarg(int *) status; 696 syscallarg(int) options; 697 syscallarg(struct rusage *) rusage; 698 } */ 699 int error, status, pid = SCARG(uap, pid); 700 struct rusage ru; 701 702 error = do_sys_wait(&pid, &status, SCARG(uap, options), 703 SCARG(uap, rusage) != NULL ? &ru : NULL); 704 705 retval[0] = pid; 706 if (pid == 0) { 707 return error; 708 } 709 if (SCARG(uap, status)) { 710 error = copyout(&status, SCARG(uap, status), sizeof(status)); 711 } 712 if (SCARG(uap, rusage) && error == 0) { 713 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 714 } 715 return error; 716 } 717 718 /* 719 * Scan list of child processes for a child process that has stopped or 720 * exited. Used by sys_wait4 and 'compat' equivalents. 721 * 722 * Must be called with the proc_lock held, and may release while waiting. 723 */ 724 static int 725 find_stopped_child(struct proc *parent, pid_t pid, int options, 726 struct proc **child_p, int *status_p) 727 { 728 struct proc *child, *dead; 729 int error; 730 731 KASSERT(mutex_owned(proc_lock)); 732 733 if (options & ~(WUNTRACED|WNOHANG|WALTSIG|WALLSIG) 734 && !(options & WOPTSCHECKED)) { 735 *child_p = NULL; 736 return EINVAL; 737 } 738 739 if (pid == 0 && !(options & WOPTSCHECKED)) 740 pid = -parent->p_pgid; 741 742 for (;;) { 743 error = ECHILD; 744 dead = NULL; 745 746 LIST_FOREACH(child, &parent->p_children, p_sibling) { 747 if (pid >= 0) { 748 if (child->p_pid != pid) { 749 child = proc_find_raw(pid); 750 if (child == NULL || 751 child->p_stat == SIDL || 752 child->p_pptr != parent) { 753 child = NULL; 754 break; 755 } 756 } 757 } else if (pid != WAIT_ANY && child->p_pgid != -pid) { 758 /* Child not in correct pgrp */ 759 continue; 760 } 761 762 /* 763 * Wait for processes with p_exitsig != SIGCHLD 764 * processes only if WALTSIG is set; wait for 765 * processes with p_exitsig == SIGCHLD only 766 * if WALTSIG is clear. 767 */ 768 if (((options & WALLSIG) == 0) && 769 (options & WALTSIG ? child->p_exitsig == SIGCHLD 770 : P_EXITSIG(child) != SIGCHLD)){ 771 if (child->p_pid == pid) { 772 child = NULL; 773 break; 774 } 775 continue; 776 } 777 778 error = 0; 779 if ((options & WNOZOMBIE) == 0) { 780 if (child->p_stat == SZOMB) 781 break; 782 if (child->p_stat == SDEAD) { 783 /* 784 * We may occasionally arrive here 785 * after receiving a signal, but 786 * immediately before the child 787 * process is zombified. The wait 788 * will be short, so avoid returning 789 * to userspace. 790 */ 791 dead = child; 792 } 793 } 794 795 if (child->p_stat == SSTOP && 796 child->p_waited == 0 && 797 (child->p_slflag & PSL_TRACED || 798 options & WUNTRACED)) { 799 if ((options & WNOWAIT) == 0) { 800 child->p_waited = 1; 801 parent->p_nstopchild--; 802 } 803 break; 804 } 805 if (parent->p_nstopchild == 0 || child->p_pid == pid) { 806 child = NULL; 807 break; 808 } 809 } 810 811 if (child != NULL || error != 0 || 812 ((options & WNOHANG) != 0 && dead == NULL)) { 813 if (child != NULL) { 814 *status_p = child->p_xstat; 815 } 816 *child_p = child; 817 return error; 818 } 819 820 /* 821 * Wait for another child process to stop. 822 */ 823 error = cv_wait_sig(&parent->p_waitcv, proc_lock); 824 825 if (error != 0) { 826 *child_p = NULL; 827 return error; 828 } 829 } 830 } 831 832 /* 833 * Free a process after parent has taken all the state info. Must be called 834 * with the proclist lock held, and will release before returning. 835 * 836 * *ru is returned to the caller, and must be freed by the caller. 837 */ 838 static void 839 proc_free(struct proc *p, struct rusage *ru) 840 { 841 struct proc *parent = p->p_pptr; 842 struct lwp *l; 843 ksiginfo_t ksi; 844 kauth_cred_t cred1, cred2; 845 uid_t uid; 846 847 KASSERT(mutex_owned(proc_lock)); 848 KASSERT(p->p_nlwps == 1); 849 KASSERT(p->p_nzlwps == 1); 850 KASSERT(p->p_nrlwps == 0); 851 KASSERT(p->p_stat == SZOMB); 852 853 /* 854 * If we got the child via ptrace(2) or procfs, and 855 * the parent is different (meaning the process was 856 * attached, rather than run as a child), then we need 857 * to give it back to the old parent, and send the 858 * parent the exit signal. The rest of the cleanup 859 * will be done when the old parent waits on the child. 860 */ 861 if ((p->p_slflag & PSL_TRACED) != 0 && p->p_opptr != parent) { 862 mutex_enter(p->p_lock); 863 p->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 864 mutex_exit(p->p_lock); 865 parent = (p->p_opptr == NULL) ? initproc : p->p_opptr; 866 proc_reparent(p, parent); 867 p->p_opptr = NULL; 868 if (p->p_exitsig != 0) { 869 exit_psignal(p, parent, &ksi); 870 kpsignal(parent, &ksi, NULL); 871 } 872 cv_broadcast(&parent->p_waitcv); 873 mutex_exit(proc_lock); 874 return; 875 } 876 877 sched_proc_exit(parent, p); 878 879 /* 880 * Add child times of exiting process onto its own times. 881 * This cannot be done any earlier else it might get done twice. 882 */ 883 l = LIST_FIRST(&p->p_lwps); 884 p->p_stats->p_ru.ru_nvcsw += (l->l_ncsw - l->l_nivcsw); 885 p->p_stats->p_ru.ru_nivcsw += l->l_nivcsw; 886 ruadd(&p->p_stats->p_ru, &l->l_ru); 887 ruadd(&p->p_stats->p_ru, &p->p_stats->p_cru); 888 ruadd(&parent->p_stats->p_cru, &p->p_stats->p_ru); 889 if (ru != NULL) 890 *ru = p->p_stats->p_ru; 891 p->p_xstat = 0; 892 893 /* 894 * At this point we are going to start freeing the final resources. 895 * If anyone tries to access the proc structure after here they will 896 * get a shock - bits are missing. Attempt to make it hard! We 897 * don't bother with any further locking past this point. 898 */ 899 p->p_stat = SIDL; /* not even a zombie any more */ 900 LIST_REMOVE(p, p_list); /* off zombproc */ 901 parent->p_nstopchild--; 902 LIST_REMOVE(p, p_sibling); 903 904 /* 905 * Let pid be reallocated. 906 */ 907 proc_free_pid(p->p_pid); 908 909 /* 910 * Unlink process from its process group. 911 * Releases the proc_lock. 912 */ 913 proc_leavepgrp(p); 914 915 /* 916 * Delay release until after lwp_free. 917 */ 918 cred2 = l->l_cred; 919 920 /* 921 * Free the last LWP's resources. 922 * 923 * lwp_free ensures the LWP is no longer running on another CPU. 924 */ 925 lwp_free(l, false, true); 926 927 /* 928 * Now no one except us can reach the process p. 929 */ 930 931 /* 932 * Decrement the count of procs running with this uid. 933 */ 934 cred1 = p->p_cred; 935 uid = kauth_cred_getuid(cred1); 936 (void)chgproccnt(uid, -1); 937 938 /* 939 * Release substructures. 940 */ 941 942 lim_free(p->p_limit); 943 pstatsfree(p->p_stats); 944 kauth_cred_free(cred1); 945 kauth_cred_free(cred2); 946 947 /* 948 * Release reference to text vnode 949 */ 950 if (p->p_textvp) 951 vrele(p->p_textvp); 952 953 mutex_destroy(&p->p_auxlock); 954 mutex_obj_free(p->p_lock); 955 mutex_destroy(&p->p_stmutex); 956 cv_destroy(&p->p_waitcv); 957 cv_destroy(&p->p_lwpcv); 958 rw_destroy(&p->p_reflock); 959 960 proc_free_mem(p); 961 } 962 963 /* 964 * make process 'parent' the new parent of process 'child'. 965 * 966 * Must be called with proc_lock held. 967 */ 968 void 969 proc_reparent(struct proc *child, struct proc *parent) 970 { 971 972 KASSERT(mutex_owned(proc_lock)); 973 974 if (child->p_pptr == parent) 975 return; 976 977 if (child->p_stat == SZOMB || 978 (child->p_stat == SSTOP && !child->p_waited)) { 979 child->p_pptr->p_nstopchild--; 980 parent->p_nstopchild++; 981 } 982 if (parent == initproc) 983 child->p_exitsig = SIGCHLD; 984 985 LIST_REMOVE(child, p_sibling); 986 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 987 child->p_pptr = parent; 988 child->p_ppid = parent->p_pid; 989 } 990