1 /* $NetBSD: kern_exit.c,v 1.213 2008/10/15 06:51:20 wrstuden 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 1.213 2008/10/15 06:51:20 wrstuden Exp $"); 71 72 #include "opt_ktrace.h" 73 #include "opt_perfctrs.h" 74 #include "opt_sa.h" 75 #include "opt_sysv.h" 76 77 #include <sys/param.h> 78 #include <sys/aio.h> 79 #include <sys/systm.h> 80 #include <sys/ioctl.h> 81 #include <sys/tty.h> 82 #include <sys/time.h> 83 #include <sys/resource.h> 84 #include <sys/kernel.h> 85 #include <sys/proc.h> 86 #include <sys/buf.h> 87 #include <sys/wait.h> 88 #include <sys/file.h> 89 #include <sys/vnode.h> 90 #include <sys/syslog.h> 91 #include <sys/malloc.h> 92 #include <sys/pool.h> 93 #include <sys/uidinfo.h> 94 #if defined(PERFCTRS) 95 #include <sys/pmc.h> 96 #endif 97 #include <sys/ptrace.h> 98 #include <sys/acct.h> 99 #include <sys/filedesc.h> 100 #include <sys/ras.h> 101 #include <sys/signalvar.h> 102 #include <sys/sched.h> 103 #include <sys/sa.h> 104 #include <sys/savar.h> 105 #include <sys/mount.h> 106 #include <sys/syscallargs.h> 107 #include <sys/kauth.h> 108 #include <sys/sleepq.h> 109 #include <sys/lockdebug.h> 110 #include <sys/ktrace.h> 111 #include <sys/cpu.h> 112 #include <sys/lwpctl.h> 113 #include <sys/atomic.h> 114 115 #include <uvm/uvm_extern.h> 116 117 #define DEBUG_EXIT 118 119 #ifdef DEBUG_EXIT 120 int debug_exit = 0; 121 #define DPRINTF(x) if (debug_exit) printf x 122 #else 123 #define DPRINTF(x) 124 #endif 125 126 static int find_stopped_child(struct proc *, pid_t, int, struct proc **, int *); 127 static void proc_free(struct proc *, struct rusage *); 128 129 /* 130 * Fill in the appropriate signal information, and signal the parent. 131 */ 132 static void 133 exit_psignal(struct proc *p, struct proc *pp, ksiginfo_t *ksi) 134 { 135 136 KSI_INIT(ksi); 137 if ((ksi->ksi_signo = P_EXITSIG(p)) == SIGCHLD) { 138 if (WIFSIGNALED(p->p_xstat)) { 139 if (WCOREDUMP(p->p_xstat)) 140 ksi->ksi_code = CLD_DUMPED; 141 else 142 ksi->ksi_code = CLD_KILLED; 143 } else { 144 ksi->ksi_code = CLD_EXITED; 145 } 146 } 147 /* 148 * We fill those in, even for non-SIGCHLD. 149 * It's safe to access p->p_cred unlocked here. 150 */ 151 ksi->ksi_pid = p->p_pid; 152 ksi->ksi_uid = kauth_cred_geteuid(p->p_cred); 153 ksi->ksi_status = p->p_xstat; 154 /* XXX: is this still valid? */ 155 ksi->ksi_utime = p->p_stats->p_ru.ru_utime.tv_sec; 156 ksi->ksi_stime = p->p_stats->p_ru.ru_stime.tv_sec; 157 } 158 159 /* 160 * exit -- 161 * Death of process. 162 */ 163 int 164 sys_exit(struct lwp *l, const struct sys_exit_args *uap, register_t *retval) 165 { 166 /* { 167 syscallarg(int) rval; 168 } */ 169 struct proc *p = l->l_proc; 170 171 /* Don't call exit1() multiple times in the same process. */ 172 mutex_enter(p->p_lock); 173 if (p->p_sflag & PS_WEXIT) { 174 mutex_exit(p->p_lock); 175 lwp_exit(l); 176 } 177 178 /* exit1() will release the mutex. */ 179 exit1(l, W_EXITCODE(SCARG(uap, rval), 0)); 180 /* NOTREACHED */ 181 return (0); 182 } 183 184 /* 185 * Exit: deallocate address space and other resources, change proc state 186 * to zombie, and unlink proc from allproc and parent's lists. Save exit 187 * status and rusage for wait(). Check for child processes and orphan them. 188 * 189 * Must be called with p->p_lock held. Does not return. 190 */ 191 void 192 exit1(struct lwp *l, int rv) 193 { 194 struct proc *p, *q, *nq; 195 struct pgrp *pgrp; 196 ksiginfo_t ksi; 197 ksiginfoq_t kq; 198 int wakeinit, sa; 199 200 p = l->l_proc; 201 202 KASSERT(mutex_owned(p->p_lock)); 203 204 if (__predict_false(p == initproc)) 205 panic("init died (signal %d, exit %d)", 206 WTERMSIG(rv), WEXITSTATUS(rv)); 207 208 /* 209 * Disable scheduler activation upcalls. We're trying to get out of 210 * here. 211 */ 212 sa = 0; 213 #ifdef KERN_SA 214 if ((p->p_sa != NULL)) { 215 l->l_pflag |= LP_SA_NOBLOCK; 216 sa = 1; 217 } 218 #endif 219 220 p->p_sflag |= PS_WEXIT; 221 222 /* 223 * Force all other LWPs to exit before we do. Only then can we 224 * begin to tear down the rest of the process state. 225 */ 226 if (sa || p->p_nlwps > 1) 227 exit_lwps(l); 228 229 ksiginfo_queue_init(&kq); 230 231 /* 232 * If we have been asked to stop on exit, do so now. 233 */ 234 if (__predict_false(p->p_sflag & PS_STOPEXIT)) { 235 KERNEL_UNLOCK_ALL(l, &l->l_biglocks); 236 sigclearall(p, &contsigmask, &kq); 237 p->p_waited = 0; 238 membar_producer(); 239 p->p_stat = SSTOP; 240 lwp_lock(l); 241 p->p_nrlwps--; 242 l->l_stat = LSSTOP; 243 mutex_exit(p->p_lock); 244 mi_switch(l); 245 KERNEL_LOCK(l->l_biglocks, l); 246 mutex_enter(p->p_lock); 247 } 248 249 /* 250 * Bin any remaining signals and mark the process as dying so it will 251 * not be found for, e.g. signals. 252 */ 253 sigfillset(&p->p_sigctx.ps_sigignore); 254 sigclearall(p, NULL, &kq); 255 p->p_stat = SDYING; 256 mutex_exit(p->p_lock); 257 ksiginfo_queue_drain(&kq); 258 259 /* Destroy any lwpctl info. */ 260 if (p->p_lwpctl != NULL) 261 lwp_ctl_exit(); 262 263 /* Destroy all AIO works */ 264 aio_exit(p, p->p_aio); 265 266 /* 267 * Drain all remaining references that procfs, ptrace and others may 268 * have on the process. 269 */ 270 rw_enter(&p->p_reflock, RW_WRITER); 271 272 DPRINTF(("exit1: %d.%d exiting.\n", p->p_pid, l->l_lid)); 273 274 timers_free(p, TIMERS_ALL); 275 #if defined(__HAVE_RAS) 276 ras_purgeall(); 277 #endif 278 279 /* 280 * Close open files, release open-file table and free signal 281 * actions. This may block! 282 */ 283 fd_free(); 284 cwdfree(p->p_cwdi); 285 p->p_cwdi = NULL; 286 doexithooks(p); 287 sigactsfree(p->p_sigacts); 288 289 /* 290 * Write out accounting data. 291 */ 292 (void)acct_process(l); 293 294 #ifdef KTRACE 295 /* 296 * Release trace file. 297 */ 298 if (p->p_tracep != NULL) { 299 mutex_enter(&ktrace_lock); 300 ktrderef(p); 301 mutex_exit(&ktrace_lock); 302 } 303 #endif 304 305 /* 306 * If emulation has process exit hook, call it now. 307 * Set the exit status now so that the exit hook has 308 * an opportunity to tweak it (COMPAT_LINUX requires 309 * this for thread group emulation) 310 */ 311 p->p_xstat = rv; 312 if (p->p_emul->e_proc_exit) 313 (*p->p_emul->e_proc_exit)(p); 314 315 /* 316 * Free the VM resources we're still holding on to. 317 * We must do this from a valid thread because doing 318 * so may block. This frees vmspace, which we don't 319 * need anymore. The only remaining lwp is the one 320 * we run at this moment, nothing runs in userland 321 * anymore. 322 */ 323 uvm_proc_exit(p); 324 325 /* 326 * Stop profiling. 327 */ 328 if (__predict_false((p->p_stflag & PST_PROFIL) != 0)) { 329 mutex_spin_enter(&p->p_stmutex); 330 stopprofclock(p); 331 mutex_spin_exit(&p->p_stmutex); 332 } 333 334 /* 335 * If parent is waiting for us to exit or exec, P_PPWAIT is set; we 336 * wake up the parent early to avoid deadlock. We can do this once 337 * the VM resources are released. 338 */ 339 mutex_enter(proc_lock); 340 if (p->p_lflag & PL_PPWAIT) { 341 p->p_lflag &= ~PL_PPWAIT; 342 cv_broadcast(&p->p_pptr->p_waitcv); 343 } 344 345 if (SESS_LEADER(p)) { 346 struct vnode *vprele = NULL, *vprevoke = NULL; 347 struct session *sp = p->p_session; 348 struct tty *tp; 349 350 if (sp->s_ttyvp) { 351 /* 352 * Controlling process. 353 * Signal foreground pgrp, 354 * drain controlling terminal 355 * and revoke access to controlling terminal. 356 */ 357 tp = sp->s_ttyp; 358 mutex_spin_enter(&tty_lock); 359 if (tp->t_session == sp) { 360 /* we can't guarantee the revoke will do this */ 361 pgrp = tp->t_pgrp; 362 tp->t_pgrp = NULL; 363 tp->t_session = NULL; 364 mutex_spin_exit(&tty_lock); 365 if (pgrp != NULL) { 366 pgsignal(pgrp, SIGHUP, 1); 367 } 368 mutex_exit(proc_lock); 369 (void) ttywait(tp); 370 mutex_enter(proc_lock); 371 372 /* The tty could have been revoked. */ 373 vprevoke = sp->s_ttyvp; 374 } else 375 mutex_spin_exit(&tty_lock); 376 vprele = sp->s_ttyvp; 377 sp->s_ttyvp = NULL; 378 /* 379 * s_ttyp is not zero'd; we use this to indicate 380 * that the session once had a controlling terminal. 381 * (for logging and informational purposes) 382 */ 383 } 384 sp->s_leader = NULL; 385 386 if (vprevoke != NULL || vprele != NULL) { 387 if (vprevoke != NULL) { 388 SESSRELE(sp); 389 mutex_exit(proc_lock); 390 VOP_REVOKE(vprevoke, REVOKEALL); 391 } else 392 mutex_exit(proc_lock); 393 if (vprele != NULL) 394 vrele(vprele); 395 mutex_enter(proc_lock); 396 } 397 } 398 fixjobc(p, p->p_pgrp, 0); 399 400 /* 401 * Finalize the last LWP's specificdata, as well as the 402 * specificdata for the proc itself. 403 */ 404 lwp_finispecific(l); 405 proc_finispecific(p); 406 407 /* 408 * Notify interested parties of our demise. 409 */ 410 KNOTE(&p->p_klist, NOTE_EXIT); 411 412 #if PERFCTRS 413 /* 414 * Save final PMC information in parent process & clean up. 415 */ 416 if (PMC_ENABLED(p)) { 417 pmc_save_context(p); 418 pmc_accumulate(p->p_pptr, p); 419 pmc_process_exit(p); 420 } 421 #endif 422 423 /* 424 * Reset p_opptr pointer of all former children which got 425 * traced by another process and were reparented. We reset 426 * it to NULL here; the trace detach code then reparents 427 * the child to initproc. We only check allproc list, since 428 * eventual former children on zombproc list won't reference 429 * p_opptr anymore. 430 */ 431 if (__predict_false(p->p_slflag & PSL_CHTRACED)) { 432 PROCLIST_FOREACH(q, &allproc) { 433 if ((q->p_flag & PK_MARKER) != 0) 434 continue; 435 if (q->p_opptr == p) 436 q->p_opptr = NULL; 437 } 438 } 439 440 /* 441 * Give orphaned children to init(8). 442 */ 443 q = LIST_FIRST(&p->p_children); 444 wakeinit = (q != NULL); 445 for (; q != NULL; q = nq) { 446 nq = LIST_NEXT(q, p_sibling); 447 448 /* 449 * Traced processes are killed since their existence 450 * means someone is screwing up. Since we reset the 451 * trace flags, the logic in sys_wait4() would not be 452 * triggered to reparent the process to its 453 * original parent, so we must do this here. 454 */ 455 if (__predict_false(q->p_slflag & PSL_TRACED)) { 456 mutex_enter(p->p_lock); 457 q->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 458 mutex_exit(p->p_lock); 459 if (q->p_opptr != q->p_pptr) { 460 struct proc *t = q->p_opptr; 461 proc_reparent(q, t ? t : initproc); 462 q->p_opptr = NULL; 463 } else 464 proc_reparent(q, initproc); 465 killproc(q, "orphaned traced process"); 466 } else 467 proc_reparent(q, initproc); 468 } 469 470 /* 471 * Move proc from allproc to zombproc, it's now nearly ready to be 472 * collected by parent. 473 */ 474 LIST_REMOVE(l, l_list); 475 LIST_REMOVE(p, p_list); 476 LIST_INSERT_HEAD(&zombproc, p, p_list); 477 478 /* 479 * Mark the process as dead. We must do this before we signal 480 * the parent. 481 */ 482 p->p_stat = SDEAD; 483 484 /* Put in front of parent's sibling list for parent to collect it */ 485 q = p->p_pptr; 486 q->p_nstopchild++; 487 if (LIST_FIRST(&q->p_children) != p) { 488 /* Put child where it can be found quickly */ 489 LIST_REMOVE(p, p_sibling); 490 LIST_INSERT_HEAD(&q->p_children, p, p_sibling); 491 } 492 493 /* 494 * Notify parent that we're gone. If parent has the P_NOCLDWAIT 495 * flag set, notify init instead (and hope it will handle 496 * this situation). 497 */ 498 if (q->p_flag & (PK_NOCLDWAIT|PK_CLDSIGIGN)) { 499 proc_reparent(p, initproc); 500 wakeinit = 1; 501 502 /* 503 * If this was the last child of our parent, notify 504 * parent, so in case he was wait(2)ing, he will 505 * continue. 506 */ 507 if (LIST_FIRST(&q->p_children) == NULL) 508 cv_broadcast(&q->p_waitcv); 509 } 510 511 /* Reload parent pointer, since p may have been reparented above */ 512 q = p->p_pptr; 513 514 if (__predict_false((p->p_slflag & PSL_FSTRACE) == 0 && p->p_exitsig != 0)) { 515 exit_psignal(p, q, &ksi); 516 kpsignal(q, &ksi, NULL); 517 } 518 519 /* Calculate the final rusage info. */ 520 calcru(p, &p->p_stats->p_ru.ru_utime, &p->p_stats->p_ru.ru_stime, 521 NULL, NULL); 522 523 if (wakeinit) 524 cv_broadcast(&initproc->p_waitcv); 525 526 callout_destroy(&l->l_timeout_ch); 527 528 /* 529 * Remaining lwp resources will be freed in lwp_exit2() once we've 530 * switch to idle context; at that point, we will be marked as a 531 * full blown zombie. 532 */ 533 mutex_enter(p->p_lock); 534 lwp_drainrefs(l); 535 lwp_lock(l); 536 l->l_prflag &= ~LPR_DETACHED; 537 l->l_stat = LSZOMB; 538 lwp_unlock(l); 539 KASSERT(curlwp == l); 540 KASSERT(p->p_nrlwps == 1); 541 KASSERT(p->p_nlwps == 1); 542 p->p_stat = SZOMB; 543 p->p_nrlwps--; 544 p->p_nzlwps++; 545 p->p_ndlwps = 0; 546 mutex_exit(p->p_lock); 547 548 /* 549 * Signal the parent to collect us, and drop the proclist lock. 550 * Drop debugger/procfs lock; no new references can be gained. 551 */ 552 cv_broadcast(&p->p_pptr->p_waitcv); 553 mutex_exit(proc_lock); 554 rw_exit(&p->p_reflock); 555 556 /* Verify that we hold no locks other than the kernel lock. */ 557 LOCKDEBUG_BARRIER(&kernel_lock, 0); 558 559 /* 560 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 561 */ 562 563 /* 564 * Give machine-dependent code a chance to free any MD LWP 565 * resources. This must be done before uvm_lwp_exit(), in 566 * case these resources are in the PCB. 567 */ 568 #ifndef __NO_CPU_LWP_FREE 569 cpu_lwp_free(l, 1); 570 #endif 571 pmap_deactivate(l); 572 573 /* This process no longer needs to hold the kernel lock. */ 574 #ifdef notyet 575 /* XXXSMP hold in lwp_userret() */ 576 KERNEL_UNLOCK_LAST(l); 577 #else 578 KERNEL_UNLOCK_ALL(l, NULL); 579 #endif 580 581 lwp_exit_switchaway(l); 582 } 583 584 void 585 exit_lwps(struct lwp *l) 586 { 587 struct proc *p; 588 struct lwp *l2; 589 int error; 590 lwpid_t waited; 591 int nlocks; 592 593 KERNEL_UNLOCK_ALL(l, &nlocks); 594 595 p = l->l_proc; 596 KASSERT(mutex_owned(p->p_lock)); 597 598 #if 0 599 if (p->p_sa != NULL) { 600 SLIST_FOREACH(vp, &p->p_sa->sa_vps, savp_next) { 601 /* 602 * Make SA-cached LWPs normal process runnable 603 * LWPs so that they'll also self-destruct. 604 */ 605 DPRINTF(("exit_lwps: Making cached LWPs of %d on " 606 "VP %d runnable: ", p->p_pid, vp->savp_id)); 607 while ((l2 = sa_getcachelwp(p, vp)) != 0) { 608 lwp_lock(l2); 609 l2->l_flag = (l2->l_flag & ~LW_SA) | LW_WEXIT; 610 l2->l_priority = MAXPRI_USER; /* XXX WRS needs thought */ 611 612 /* setrunnable() will release the mutex. */ 613 setrunnable(l2); 614 DPRINTF(("%d ", l2->l_lid)); 615 } 616 DPRINTF(("\n")); 617 618 /* 619 * Clear wokenq, the LWPs on the queue will 620 * run below. Workes as these threads are still 621 * on the p_lwps list (even though they are no longer 622 * counted). 623 */ 624 TAILQ_INIT(&vp->savp_woken); 625 } 626 } 627 #endif 628 629 retry: 630 /* 631 * Interrupt LWPs in interruptable sleep, unsuspend suspended 632 * LWPs and then wait for everyone else to finish. 633 */ 634 LIST_FOREACH(l2, &p->p_lwps, l_sibling) { 635 if (l2 == l) 636 continue; 637 lwp_lock(l2); 638 l2->l_flag &= ~LW_SA; 639 l2->l_flag |= LW_WEXIT; 640 if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) || 641 l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) { 642 /* setrunnable() will release the lock. */ 643 setrunnable(l2); 644 DPRINTF(("exit_lwps: Made %d.%d runnable\n", 645 p->p_pid, l2->l_lid)); 646 continue; 647 } 648 lwp_unlock(l2); 649 } 650 while (p->p_nlwps > 1) { 651 DPRINTF(("exit_lwps: waiting for %d LWPs (%d zombies)\n", 652 p->p_nlwps, p->p_nzlwps)); 653 error = lwp_wait1(l, 0, &waited, LWPWAIT_EXITCONTROL); 654 if (p->p_nlwps == 1) 655 break; 656 if (error == EDEADLK) { 657 /* 658 * LWPs can get suspended/slept behind us. 659 * (eg. sa_setwoken) 660 * kick them again and retry. 661 */ 662 goto retry; 663 } 664 if (error) 665 panic("exit_lwps: lwp_wait1 failed with error %d", 666 error); 667 DPRINTF(("exit_lwps: Got LWP %d from lwp_wait1()\n", waited)); 668 } 669 670 KERNEL_LOCK(nlocks, l); 671 KASSERT(p->p_nlwps == 1); 672 } 673 674 int 675 do_sys_wait(struct lwp *l, int *pid, int *status, int options, 676 struct rusage *ru, int *was_zombie) 677 { 678 struct proc *child; 679 int error; 680 681 mutex_enter(proc_lock); 682 error = find_stopped_child(l->l_proc, *pid, options, &child, status); 683 684 if (child == NULL) { 685 mutex_exit(proc_lock); 686 *pid = 0; 687 return error; 688 } 689 690 *pid = child->p_pid; 691 692 if (child->p_stat == SZOMB) { 693 /* proc_free() will release the proc_lock. */ 694 *was_zombie = 1; 695 if (options & WNOWAIT) 696 mutex_exit(proc_lock); 697 else { 698 proc_free(child, ru); 699 } 700 } else { 701 /* Child state must have been SSTOP. */ 702 *was_zombie = 0; 703 mutex_exit(proc_lock); 704 *status = W_STOPCODE(*status); 705 } 706 707 return 0; 708 } 709 710 int 711 sys_wait4(struct lwp *l, const struct sys_wait4_args *uap, register_t *retval) 712 { 713 /* { 714 syscallarg(int) pid; 715 syscallarg(int *) status; 716 syscallarg(int) options; 717 syscallarg(struct rusage *) rusage; 718 } */ 719 int status, error; 720 int was_zombie; 721 struct rusage ru; 722 int pid = SCARG(uap, pid); 723 724 error = do_sys_wait(l, &pid, &status, SCARG(uap, options), 725 SCARG(uap, rusage) != NULL ? &ru : NULL, &was_zombie); 726 727 retval[0] = pid; 728 if (pid == 0) 729 return error; 730 731 if (SCARG(uap, rusage)) 732 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 733 734 if (error == 0 && SCARG(uap, status)) 735 error = copyout(&status, SCARG(uap, status), sizeof(status)); 736 737 return error; 738 } 739 740 /* 741 * Scan list of child processes for a child process that has stopped or 742 * exited. Used by sys_wait4 and 'compat' equivalents. 743 * 744 * Must be called with the proc_lock held, and may release while waiting. 745 */ 746 static int 747 find_stopped_child(struct proc *parent, pid_t pid, int options, 748 struct proc **child_p, int *status_p) 749 { 750 struct proc *child, *dead; 751 int error; 752 753 KASSERT(mutex_owned(proc_lock)); 754 755 if (options & ~(WUNTRACED|WNOHANG|WALTSIG|WALLSIG) 756 && !(options & WOPTSCHECKED)) { 757 *child_p = NULL; 758 return EINVAL; 759 } 760 761 if (pid == 0 && !(options & WOPTSCHECKED)) 762 pid = -parent->p_pgid; 763 764 for (;;) { 765 error = ECHILD; 766 dead = NULL; 767 768 LIST_FOREACH(child, &parent->p_children, p_sibling) { 769 if (pid >= 0) { 770 if (child->p_pid != pid) { 771 child = p_find(pid, PFIND_ZOMBIE | 772 PFIND_LOCKED); 773 if (child == NULL || 774 child->p_pptr != parent) { 775 child = NULL; 776 break; 777 } 778 } 779 } else if (pid != WAIT_ANY && child->p_pgid != -pid) { 780 /* Child not in correct pgrp */ 781 continue; 782 } 783 784 /* 785 * Wait for processes with p_exitsig != SIGCHLD 786 * processes only if WALTSIG is set; wait for 787 * processes with p_exitsig == SIGCHLD only 788 * if WALTSIG is clear. 789 */ 790 if (((options & WALLSIG) == 0) && 791 (options & WALTSIG ? child->p_exitsig == SIGCHLD 792 : P_EXITSIG(child) != SIGCHLD)){ 793 if (child->p_pid == pid) { 794 child = NULL; 795 break; 796 } 797 continue; 798 } 799 800 error = 0; 801 if ((options & WNOZOMBIE) == 0) { 802 if (child->p_stat == SZOMB) 803 break; 804 if (child->p_stat == SDEAD) { 805 /* 806 * We may occasionally arrive here 807 * after receiving a signal, but 808 * immediatley before the child 809 * process is zombified. The wait 810 * will be short, so avoid returning 811 * to userspace. 812 */ 813 dead = child; 814 } 815 } 816 817 if (child->p_stat == SSTOP && 818 child->p_waited == 0 && 819 (child->p_slflag & PSL_TRACED || 820 options & WUNTRACED)) { 821 if ((options & WNOWAIT) == 0) { 822 child->p_waited = 1; 823 parent->p_nstopchild--; 824 } 825 break; 826 } 827 if (parent->p_nstopchild == 0 || child->p_pid == pid) { 828 child = NULL; 829 break; 830 } 831 } 832 833 if (child != NULL || error != 0 || 834 ((options & WNOHANG) != 0 && dead == NULL)) { 835 if (child != NULL) { 836 *status_p = child->p_xstat; 837 } 838 *child_p = child; 839 return error; 840 } 841 842 /* 843 * Wait for another child process to stop. 844 */ 845 error = cv_wait_sig(&parent->p_waitcv, proc_lock); 846 847 if (error != 0) { 848 *child_p = NULL; 849 return error; 850 } 851 } 852 } 853 854 /* 855 * Free a process after parent has taken all the state info. Must be called 856 * with the proclist lock held, and will release before returning. 857 * 858 * *ru is returned to the caller, and must be freed by the caller. 859 */ 860 static void 861 proc_free(struct proc *p, struct rusage *ru) 862 { 863 struct proc *parent; 864 struct lwp *l; 865 ksiginfo_t ksi; 866 kauth_cred_t cred1, cred2; 867 uid_t uid; 868 869 KASSERT(mutex_owned(proc_lock)); 870 KASSERT(p->p_nlwps == 1); 871 KASSERT(p->p_nzlwps == 1); 872 KASSERT(p->p_nrlwps == 0); 873 KASSERT(p->p_stat == SZOMB); 874 875 /* 876 * If we got the child via ptrace(2) or procfs, and 877 * the parent is different (meaning the process was 878 * attached, rather than run as a child), then we need 879 * to give it back to the old parent, and send the 880 * parent the exit signal. The rest of the cleanup 881 * will be done when the old parent waits on the child. 882 */ 883 if ((p->p_slflag & PSL_TRACED) != 0) { 884 parent = p->p_pptr; 885 if (p->p_opptr != parent){ 886 mutex_enter(p->p_lock); 887 p->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 888 mutex_exit(p->p_lock); 889 parent = p->p_opptr; 890 if (parent == NULL) 891 parent = initproc; 892 proc_reparent(p, parent); 893 p->p_opptr = NULL; 894 if (p->p_exitsig != 0) { 895 exit_psignal(p, parent, &ksi); 896 kpsignal(parent, &ksi, NULL); 897 } 898 cv_broadcast(&parent->p_waitcv); 899 mutex_exit(proc_lock); 900 return; 901 } 902 } 903 904 /* 905 * Finally finished with old proc entry. Unlink it from its process 906 * group. 907 */ 908 leavepgrp(p); 909 910 parent = p->p_pptr; 911 sched_proc_exit(parent, p); 912 913 /* 914 * Add child times of exiting process onto its own times. 915 * This cannot be done any earlier else it might get done twice. 916 */ 917 l = LIST_FIRST(&p->p_lwps); 918 p->p_stats->p_ru.ru_nvcsw += (l->l_ncsw - l->l_nivcsw); 919 p->p_stats->p_ru.ru_nivcsw += l->l_nivcsw; 920 ruadd(&p->p_stats->p_ru, &l->l_ru); 921 ruadd(&p->p_stats->p_ru, &p->p_stats->p_cru); 922 ruadd(&parent->p_stats->p_cru, &p->p_stats->p_ru); 923 if (ru != NULL) 924 *ru = p->p_stats->p_ru; 925 p->p_xstat = 0; 926 927 /* Release any SA state. */ 928 #ifdef KERN_SA 929 if (p->p_sa) 930 sa_release(p); 931 #endif 932 933 /* 934 * At this point we are going to start freeing the final resources. 935 * If anyone tries to access the proc structure after here they will 936 * get a shock - bits are missing. Attempt to make it hard! We 937 * don't bother with any further locking past this point. 938 */ 939 p->p_stat = SIDL; /* not even a zombie any more */ 940 LIST_REMOVE(p, p_list); /* off zombproc */ 941 parent = p->p_pptr; 942 p->p_pptr->p_nstopchild--; 943 LIST_REMOVE(p, p_sibling); 944 945 /* 946 * Let pid be reallocated. 947 */ 948 proc_free_pid(p); 949 mutex_exit(proc_lock); 950 951 /* 952 * Delay release until after lwp_free. 953 */ 954 cred2 = l->l_cred; 955 956 /* 957 * Free the last LWP's resources. 958 * 959 * lwp_free ensures the LWP is no longer running on another CPU. 960 */ 961 lwp_free(l, false, true); 962 963 /* 964 * Now no one except us can reach the process p. 965 */ 966 967 /* 968 * Decrement the count of procs running with this uid. 969 */ 970 cred1 = p->p_cred; 971 uid = kauth_cred_getuid(cred1); 972 (void)chgproccnt(uid, -1); 973 974 /* 975 * Release substructures. 976 */ 977 978 limfree(p->p_limit); 979 pstatsfree(p->p_stats); 980 kauth_cred_free(cred1); 981 kauth_cred_free(cred2); 982 983 /* 984 * Release reference to text vnode 985 */ 986 if (p->p_textvp) 987 vrele(p->p_textvp); 988 989 mutex_destroy(&p->p_auxlock); 990 mutex_obj_free(p->p_lock); 991 mutex_destroy(&p->p_stmutex); 992 cv_destroy(&p->p_waitcv); 993 cv_destroy(&p->p_lwpcv); 994 rw_destroy(&p->p_reflock); 995 996 proc_free_mem(p); 997 } 998 999 /* 1000 * make process 'parent' the new parent of process 'child'. 1001 * 1002 * Must be called with proc_lock held. 1003 */ 1004 void 1005 proc_reparent(struct proc *child, struct proc *parent) 1006 { 1007 1008 KASSERT(mutex_owned(proc_lock)); 1009 1010 if (child->p_pptr == parent) 1011 return; 1012 1013 if (child->p_stat == SZOMB || 1014 (child->p_stat == SSTOP && !child->p_waited)) { 1015 child->p_pptr->p_nstopchild--; 1016 parent->p_nstopchild++; 1017 } 1018 if (parent == initproc) 1019 child->p_exitsig = SIGCHLD; 1020 1021 LIST_REMOVE(child, p_sibling); 1022 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 1023 child->p_pptr = parent; 1024 child->p_ppid = parent->p_pid; 1025 } 1026