1 /* $NetBSD: kern_exit.c,v 1.207 2008/04/28 20:24:03 martin 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 1.207 2008/04/28 20:24:03 martin 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/aio.h> 78 #include <sys/systm.h> 79 #include <sys/ioctl.h> 80 #include <sys/tty.h> 81 #include <sys/time.h> 82 #include <sys/resource.h> 83 #include <sys/kernel.h> 84 #include <sys/proc.h> 85 #include <sys/buf.h> 86 #include <sys/wait.h> 87 #include <sys/file.h> 88 #include <sys/vnode.h> 89 #include <sys/syslog.h> 90 #include <sys/malloc.h> 91 #include <sys/pool.h> 92 #include <sys/resourcevar.h> 93 #if defined(PERFCTRS) 94 #include <sys/pmc.h> 95 #endif 96 #include <sys/ptrace.h> 97 #include <sys/acct.h> 98 #include <sys/filedesc.h> 99 #include <sys/ras.h> 100 #include <sys/signalvar.h> 101 #include <sys/sched.h> 102 #include <sys/mount.h> 103 #include <sys/syscallargs.h> 104 #include <sys/kauth.h> 105 #include <sys/sleepq.h> 106 #include <sys/lockdebug.h> 107 #include <sys/ktrace.h> 108 #include <sys/cpu.h> 109 #include <sys/lwpctl.h> 110 #include <sys/atomic.h> 111 112 #include <uvm/uvm_extern.h> 113 114 #define DEBUG_EXIT 115 116 #ifdef DEBUG_EXIT 117 int debug_exit = 0; 118 #define DPRINTF(x) if (debug_exit) printf x 119 #else 120 #define DPRINTF(x) 121 #endif 122 123 static int find_stopped_child(struct proc *, pid_t, int, struct proc **, int *); 124 static void proc_free(struct proc *, struct rusage *); 125 126 /* 127 * Fill in the appropriate signal information, and signal the parent. 128 */ 129 static void 130 exit_psignal(struct proc *p, struct proc *pp, ksiginfo_t *ksi) 131 { 132 133 KSI_INIT(ksi); 134 if ((ksi->ksi_signo = P_EXITSIG(p)) == SIGCHLD) { 135 if (WIFSIGNALED(p->p_xstat)) { 136 if (WCOREDUMP(p->p_xstat)) 137 ksi->ksi_code = CLD_DUMPED; 138 else 139 ksi->ksi_code = CLD_KILLED; 140 } else { 141 ksi->ksi_code = CLD_EXITED; 142 } 143 } 144 /* 145 * We fill those in, even for non-SIGCHLD. 146 * It's safe to access p->p_cred unlocked here. 147 */ 148 ksi->ksi_pid = p->p_pid; 149 ksi->ksi_uid = kauth_cred_geteuid(p->p_cred); 150 ksi->ksi_status = p->p_xstat; 151 /* XXX: is this still valid? */ 152 ksi->ksi_utime = p->p_stats->p_ru.ru_utime.tv_sec; 153 ksi->ksi_stime = p->p_stats->p_ru.ru_stime.tv_sec; 154 } 155 156 /* 157 * exit -- 158 * Death of process. 159 */ 160 int 161 sys_exit(struct lwp *l, const struct sys_exit_args *uap, register_t *retval) 162 { 163 /* { 164 syscallarg(int) rval; 165 } */ 166 struct proc *p = l->l_proc; 167 168 /* Don't call exit1() multiple times in the same process. */ 169 mutex_enter(p->p_lock); 170 if (p->p_sflag & PS_WEXIT) { 171 mutex_exit(p->p_lock); 172 lwp_exit(l); 173 } 174 175 /* exit1() will release the mutex. */ 176 exit1(l, W_EXITCODE(SCARG(uap, rval), 0)); 177 /* NOTREACHED */ 178 return (0); 179 } 180 181 /* 182 * Exit: deallocate address space and other resources, change proc state 183 * to zombie, and unlink proc from allproc and parent's lists. Save exit 184 * status and rusage for wait(). Check for child processes and orphan them. 185 * 186 * Must be called with p->p_lock held. Does not return. 187 */ 188 void 189 exit1(struct lwp *l, int rv) 190 { 191 struct proc *p, *q, *nq; 192 struct pgrp *pgrp; 193 ksiginfo_t ksi; 194 ksiginfoq_t kq; 195 int wakeinit; 196 197 p = l->l_proc; 198 199 KASSERT(mutex_owned(p->p_lock)); 200 201 if (__predict_false(p == initproc)) 202 panic("init died (signal %d, exit %d)", 203 WTERMSIG(rv), WEXITSTATUS(rv)); 204 205 p->p_sflag |= PS_WEXIT; 206 207 /* 208 * Force all other LWPs to exit before we do. Only then can we 209 * begin to tear down the rest of the process state. 210 */ 211 if (p->p_nlwps > 1) 212 exit_lwps(l); 213 214 ksiginfo_queue_init(&kq); 215 216 /* 217 * If we have been asked to stop on exit, do so now. 218 */ 219 if (p->p_sflag & PS_STOPEXIT) { 220 KERNEL_UNLOCK_ALL(l, &l->l_biglocks); 221 sigclearall(p, &contsigmask, &kq); 222 p->p_waited = 0; 223 membar_producer(); 224 p->p_stat = SSTOP; 225 lwp_lock(l); 226 p->p_nrlwps--; 227 l->l_stat = LSSTOP; 228 mutex_exit(p->p_lock); 229 mi_switch(l); 230 KERNEL_LOCK(l->l_biglocks, l); 231 } else 232 mutex_exit(p->p_lock); 233 234 /* Destroy any lwpctl info. */ 235 if (p->p_lwpctl != NULL) 236 lwp_ctl_exit(); 237 238 /* Destroy all AIO works */ 239 aio_exit(p, p->p_aio); 240 241 /* 242 * Drain all remaining references that procfs, ptrace and others may 243 * have on the process. 244 */ 245 rw_enter(&p->p_reflock, RW_WRITER); 246 247 /* 248 * Bin any remaining signals and mark the process as dying so it will 249 * not be found for, e.g. signals. 250 */ 251 mutex_enter(p->p_lock); 252 sigfillset(&p->p_sigctx.ps_sigignore); 253 sigclearall(p, NULL, &kq); 254 p->p_stat = SDYING; 255 mutex_exit(p->p_lock); 256 ksiginfo_queue_drain(&kq); 257 258 DPRINTF(("exit1: %d.%d exiting.\n", p->p_pid, l->l_lid)); 259 260 #ifdef PGINPROF 261 vmsizmon(); 262 #endif 263 timers_free(p, TIMERS_ALL); 264 #if defined(__HAVE_RAS) 265 ras_purgeall(); 266 #endif 267 268 /* 269 * Close open files, release open-file table and free signal 270 * actions. This may block! 271 */ 272 fd_free(); 273 cwdfree(p->p_cwdi); 274 p->p_cwdi = NULL; 275 doexithooks(p); 276 sigactsfree(p->p_sigacts); 277 278 /* 279 * Write out accounting data. 280 */ 281 (void)acct_process(l); 282 283 #ifdef KTRACE 284 /* 285 * Release trace file. 286 */ 287 if (p->p_tracep != NULL) { 288 mutex_enter(&ktrace_lock); 289 ktrderef(p); 290 mutex_exit(&ktrace_lock); 291 } 292 #endif 293 294 /* 295 * If emulation has process exit hook, call it now. 296 * Set the exit status now so that the exit hook has 297 * an opportunity to tweak it (COMPAT_LINUX requires 298 * this for thread group emulation) 299 */ 300 p->p_xstat = rv; 301 if (p->p_emul->e_proc_exit) 302 (*p->p_emul->e_proc_exit)(p); 303 304 /* 305 * Free the VM resources we're still holding on to. 306 * We must do this from a valid thread because doing 307 * so may block. This frees vmspace, which we don't 308 * need anymore. The only remaining lwp is the one 309 * we run at this moment, nothing runs in userland 310 * anymore. 311 */ 312 uvm_proc_exit(p); 313 314 /* 315 * While we can still block, and mark the LWP as unswappable to 316 * prevent conflicts with the with the swapper. We also shouldn't 317 * be swapped out, because we are about to exit and will release 318 * memory. 319 */ 320 uvm_lwp_hold(l); 321 322 /* 323 * Stop profiling. 324 */ 325 if ((p->p_stflag & PST_PROFIL) != 0) { 326 mutex_spin_enter(&p->p_stmutex); 327 stopprofclock(p); 328 mutex_spin_exit(&p->p_stmutex); 329 } 330 331 /* 332 * If parent is waiting for us to exit or exec, P_PPWAIT is set; we 333 * wake up the parent early to avoid deadlock. We can do this once 334 * the VM resources are released. 335 */ 336 mutex_enter(proc_lock); 337 mutex_enter(p->p_lock); 338 if (p->p_sflag & PS_PPWAIT) { 339 p->p_sflag &= ~PS_PPWAIT; 340 cv_broadcast(&p->p_pptr->p_waitcv); 341 } 342 mutex_exit(p->p_lock); 343 344 if (SESS_LEADER(p)) { 345 struct vnode *vprele = NULL, *vprevoke = NULL; 346 struct session *sp = p->p_session; 347 struct tty *tp; 348 349 if (sp->s_ttyvp) { 350 /* 351 * Controlling process. 352 * Signal foreground pgrp, 353 * drain controlling terminal 354 * and revoke access to controlling terminal. 355 */ 356 tp = sp->s_ttyp; 357 mutex_spin_enter(&tty_lock); 358 if (tp->t_session == sp) { 359 /* we can't guarantee the revoke will do this */ 360 pgrp = tp->t_pgrp; 361 tp->t_pgrp = NULL; 362 tp->t_session = NULL; 363 mutex_spin_exit(&tty_lock); 364 if (pgrp != NULL) { 365 pgsignal(pgrp, SIGHUP, 1); 366 } 367 mutex_exit(proc_lock); 368 (void) ttywait(tp); 369 mutex_enter(proc_lock); 370 371 /* The tty could have been revoked. */ 372 vprevoke = sp->s_ttyvp; 373 } else 374 mutex_spin_exit(&tty_lock); 375 vprele = sp->s_ttyvp; 376 sp->s_ttyvp = NULL; 377 /* 378 * s_ttyp is not zero'd; we use this to indicate 379 * that the session once had a controlling terminal. 380 * (for logging and informational purposes) 381 */ 382 } 383 sp->s_leader = NULL; 384 385 if (vprevoke != NULL || vprele != NULL) { 386 if (vprevoke != NULL) { 387 SESSRELE(sp); 388 mutex_exit(proc_lock); 389 VOP_REVOKE(vprevoke, REVOKEALL); 390 } else 391 mutex_exit(proc_lock); 392 if (vprele != NULL) 393 vrele(vprele); 394 mutex_enter(proc_lock); 395 } 396 } 397 fixjobc(p, p->p_pgrp, 0); 398 399 /* 400 * Finalize the last LWP's specificdata, as well as the 401 * specificdata for the proc itself. 402 */ 403 lwp_finispecific(l); 404 proc_finispecific(p); 405 406 /* 407 * Notify interested parties of our demise. 408 */ 409 KNOTE(&p->p_klist, NOTE_EXIT); 410 411 412 413 #if PERFCTRS 414 /* 415 * Save final PMC information in parent process & clean up. 416 */ 417 if (PMC_ENABLED(p)) { 418 pmc_save_context(p); 419 pmc_accumulate(p->p_pptr, p); 420 pmc_process_exit(p); 421 } 422 #endif 423 424 /* 425 * Reset p_opptr pointer of all former children which got 426 * traced by another process and were reparented. We reset 427 * it to NULL here; the trace detach code then reparents 428 * the child to initproc. We only check allproc list, since 429 * eventual former children on zombproc list won't reference 430 * p_opptr anymore. 431 */ 432 if (p->p_slflag & PSL_CHTRACED) { 433 PROCLIST_FOREACH(q, &allproc) { 434 if (q->p_opptr == p) 435 q->p_opptr = NULL; 436 } 437 } 438 439 /* 440 * Give orphaned children to init(8). 441 */ 442 q = LIST_FIRST(&p->p_children); 443 wakeinit = (q != NULL); 444 for (; q != NULL; q = nq) { 445 nq = LIST_NEXT(q, p_sibling); 446 447 /* 448 * Traced processes are killed since their existence 449 * means someone is screwing up. Since we reset the 450 * trace flags, the logic in sys_wait4() would not be 451 * triggered to reparent the process to its 452 * original parent, so we must do this here. 453 */ 454 if (q->p_slflag & PSL_TRACED) { 455 mutex_enter(p->p_lock); 456 q->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 457 mutex_exit(p->p_lock); 458 if (q->p_opptr != q->p_pptr) { 459 struct proc *t = q->p_opptr; 460 proc_reparent(q, t ? t : initproc); 461 q->p_opptr = NULL; 462 } else 463 proc_reparent(q, initproc); 464 killproc(q, "orphaned traced process"); 465 } else 466 proc_reparent(q, initproc); 467 } 468 469 /* 470 * Move proc from allproc to zombproc, it's now nearly ready to be 471 * collected by parent. 472 */ 473 LIST_REMOVE(l, l_list); 474 LIST_REMOVE(p, p_list); 475 LIST_INSERT_HEAD(&zombproc, p, p_list); 476 477 /* 478 * Mark the process as dead. We must do this before we signal 479 * the parent. 480 */ 481 p->p_stat = SDEAD; 482 483 /* Put in front of parent's sibling list for parent to collect it */ 484 q = p->p_pptr; 485 q->p_nstopchild++; 486 if (LIST_FIRST(&q->p_children) != p) { 487 /* Put child where it can be found quickly */ 488 LIST_REMOVE(p, p_sibling); 489 LIST_INSERT_HEAD(&q->p_children, p, p_sibling); 490 } 491 492 /* 493 * Notify parent that we're gone. If parent has the P_NOCLDWAIT 494 * flag set, notify init instead (and hope it will handle 495 * this situation). 496 */ 497 mutex_enter(q->p_lock); 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 mutex_exit(q->p_lock); 511 512 /* Reload parent pointer, since p may have been reparented above */ 513 q = p->p_pptr; 514 515 if ((p->p_slflag & PSL_FSTRACE) == 0 && p->p_exitsig != 0) { 516 exit_psignal(p, q, &ksi); 517 kpsignal(q, &ksi, NULL); 518 } 519 520 /* Calculate the final rusage info. */ 521 calcru(p, &p->p_stats->p_ru.ru_utime, &p->p_stats->p_ru.ru_stime, 522 NULL, NULL); 523 524 if (wakeinit) 525 cv_broadcast(&initproc->p_waitcv); 526 527 callout_destroy(&l->l_timeout_ch); 528 529 /* 530 * Remaining lwp resources will be freed in lwp_exit2() once we've 531 * switch to idle context; at that point, we will be marked as a 532 * full blown zombie. 533 */ 534 mutex_enter(p->p_lock); 535 lwp_drainrefs(l); 536 lwp_lock(l); 537 l->l_prflag &= ~LPR_DETACHED; 538 l->l_stat = LSZOMB; 539 lwp_unlock(l); 540 KASSERT(curlwp == l); 541 KASSERT(p->p_nrlwps == 1); 542 KASSERT(p->p_nlwps == 1); 543 p->p_stat = SZOMB; 544 p->p_nrlwps--; 545 p->p_nzlwps++; 546 p->p_ndlwps = 0; 547 mutex_exit(p->p_lock); 548 549 /* 550 * Signal the parent to collect us, and drop the proclist lock. 551 * Drop debugger/procfs lock; no new references can be gained. 552 */ 553 cv_broadcast(&p->p_pptr->p_waitcv); 554 mutex_exit(proc_lock); 555 rw_exit(&p->p_reflock); 556 557 /* Verify that we hold no locks other than the kernel lock. */ 558 #ifdef MULTIPROCESSOR 559 LOCKDEBUG_BARRIER(&kernel_lock, 0); 560 #else 561 LOCKDEBUG_BARRIER(NULL, 0); 562 #endif 563 564 /* 565 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 566 */ 567 568 /* 569 * Give machine-dependent code a chance to free any MD LWP 570 * resources. This must be done before uvm_lwp_exit(), in 571 * case these resources are in the PCB. 572 */ 573 #ifndef __NO_CPU_LWP_FREE 574 cpu_lwp_free(l, 1); 575 #endif 576 pmap_deactivate(l); 577 578 /* This process no longer needs to hold the kernel lock. */ 579 #ifdef notyet 580 /* XXXSMP hold in lwp_userret() */ 581 KERNEL_UNLOCK_LAST(l); 582 #else 583 KERNEL_UNLOCK_ALL(l, NULL); 584 #endif 585 586 lwp_exit_switchaway(l); 587 } 588 589 void 590 exit_lwps(struct lwp *l) 591 { 592 struct proc *p; 593 struct lwp *l2; 594 int error; 595 lwpid_t waited; 596 #if defined(MULTIPROCESSOR) 597 int nlocks; 598 #endif 599 600 KERNEL_UNLOCK_ALL(l, &nlocks); 601 602 p = l->l_proc; 603 KASSERT(mutex_owned(p->p_lock)); 604 605 retry: 606 /* 607 * Interrupt LWPs in interruptable sleep, unsuspend suspended 608 * LWPs and then wait for everyone else to finish. 609 */ 610 LIST_FOREACH(l2, &p->p_lwps, l_sibling) { 611 if (l2 == l) 612 continue; 613 lwp_lock(l2); 614 l2->l_flag |= LW_WEXIT; 615 if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) || 616 l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) { 617 /* setrunnable() will release the lock. */ 618 setrunnable(l2); 619 DPRINTF(("exit_lwps: Made %d.%d runnable\n", 620 p->p_pid, l2->l_lid)); 621 continue; 622 } 623 lwp_unlock(l2); 624 } 625 while (p->p_nlwps > 1) { 626 DPRINTF(("exit_lwps: waiting for %d LWPs (%d zombies)\n", 627 p->p_nlwps, p->p_nzlwps)); 628 error = lwp_wait1(l, 0, &waited, LWPWAIT_EXITCONTROL); 629 if (p->p_nlwps == 1) 630 break; 631 if (error == EDEADLK) { 632 /* 633 * LWPs can get suspended/slept behind us. 634 * (eg. sa_setwoken) 635 * kick them again and retry. 636 */ 637 goto retry; 638 } 639 if (error) 640 panic("exit_lwps: lwp_wait1 failed with error %d", 641 error); 642 DPRINTF(("exit_lwps: Got LWP %d from lwp_wait1()\n", waited)); 643 } 644 645 #if defined(MULTIPROCESSOR) 646 if (nlocks > 0) { 647 mutex_exit(p->p_lock); 648 KERNEL_LOCK(nlocks, l); 649 mutex_enter(p->p_lock); 650 } 651 #endif /* defined(MULTIPROCESSOR) */ 652 KASSERT(p->p_nlwps == 1); 653 } 654 655 int 656 do_sys_wait(struct lwp *l, int *pid, int *status, int options, 657 struct rusage *ru, int *was_zombie) 658 { 659 struct proc *child; 660 int error; 661 662 mutex_enter(proc_lock); 663 error = find_stopped_child(l->l_proc, *pid, options, &child, status); 664 665 if (child == NULL) { 666 mutex_exit(proc_lock); 667 *pid = 0; 668 return error; 669 } 670 671 *pid = child->p_pid; 672 673 if (child->p_stat == SZOMB) { 674 /* proc_free() will release the proc_lock. */ 675 *was_zombie = 1; 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 *was_zombie = 0; 684 mutex_exit(proc_lock); 685 *status = W_STOPCODE(*status); 686 } 687 688 return 0; 689 } 690 691 int 692 sys_wait4(struct lwp *l, const struct sys_wait4_args *uap, register_t *retval) 693 { 694 /* { 695 syscallarg(int) pid; 696 syscallarg(int *) status; 697 syscallarg(int) options; 698 syscallarg(struct rusage *) rusage; 699 } */ 700 int status, error; 701 int was_zombie; 702 struct rusage ru; 703 int pid = SCARG(uap, pid); 704 705 error = do_sys_wait(l, &pid, &status, SCARG(uap, options), 706 SCARG(uap, rusage) != NULL ? &ru : NULL, &was_zombie); 707 708 retval[0] = pid; 709 if (pid == 0) 710 return error; 711 712 if (SCARG(uap, rusage)) 713 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 714 715 if (error == 0 && SCARG(uap, status)) 716 error = copyout(&status, SCARG(uap, status), sizeof(status)); 717 718 return error; 719 } 720 721 /* 722 * Scan list of child processes for a child process that has stopped or 723 * exited. Used by sys_wait4 and 'compat' equivalents. 724 * 725 * Must be called with the proc_lock held, and may release while waiting. 726 */ 727 static int 728 find_stopped_child(struct proc *parent, pid_t pid, int options, 729 struct proc **child_p, int *status_p) 730 { 731 struct proc *child, *dead; 732 int error; 733 734 KASSERT(mutex_owned(proc_lock)); 735 736 if (options & ~(WUNTRACED|WNOHANG|WALTSIG|WALLSIG) 737 && !(options & WOPTSCHECKED)) { 738 *child_p = NULL; 739 return EINVAL; 740 } 741 742 if (pid == 0 && !(options & WOPTSCHECKED)) 743 pid = -parent->p_pgid; 744 745 for (;;) { 746 error = ECHILD; 747 dead = NULL; 748 749 LIST_FOREACH(child, &parent->p_children, p_sibling) { 750 if (pid >= 0) { 751 if (child->p_pid != pid) { 752 child = p_find(pid, PFIND_ZOMBIE | 753 PFIND_LOCKED); 754 if (child == NULL || 755 child->p_pptr != parent) { 756 child = NULL; 757 break; 758 } 759 } 760 } else if (pid != WAIT_ANY && child->p_pgid != -pid) { 761 /* Child not in correct pgrp */ 762 continue; 763 } 764 765 /* 766 * Wait for processes with p_exitsig != SIGCHLD 767 * processes only if WALTSIG is set; wait for 768 * processes with p_exitsig == SIGCHLD only 769 * if WALTSIG is clear. 770 */ 771 if (((options & WALLSIG) == 0) && 772 (options & WALTSIG ? child->p_exitsig == SIGCHLD 773 : P_EXITSIG(child) != SIGCHLD)){ 774 if (child->p_pid == pid) { 775 child = NULL; 776 break; 777 } 778 continue; 779 } 780 781 error = 0; 782 if ((options & WNOZOMBIE) == 0) { 783 if (child->p_stat == SZOMB) 784 break; 785 if (child->p_stat == SDEAD) { 786 /* 787 * We may occasionally arrive here 788 * after receiving a signal, but 789 * immediatley before the child 790 * process is zombified. The wait 791 * will be short, so avoid returning 792 * to userspace. 793 */ 794 dead = child; 795 } 796 } 797 798 if (child->p_stat == SSTOP && 799 child->p_waited == 0 && 800 (child->p_slflag & PSL_TRACED || 801 options & WUNTRACED)) { 802 if ((options & WNOWAIT) == 0) { 803 child->p_waited = 1; 804 parent->p_nstopchild--; 805 } 806 break; 807 } 808 if (parent->p_nstopchild == 0 || child->p_pid == pid) { 809 child = NULL; 810 break; 811 } 812 } 813 814 if (child != NULL || error != 0 || 815 ((options & WNOHANG) != 0 && dead == NULL)) { 816 if (child != NULL) { 817 *status_p = child->p_xstat; 818 } 819 *child_p = child; 820 return error; 821 } 822 823 /* 824 * Wait for another child process to stop. 825 */ 826 error = cv_wait_sig(&parent->p_waitcv, proc_lock); 827 828 if (error != 0) { 829 *child_p = NULL; 830 return error; 831 } 832 } 833 } 834 835 /* 836 * Free a process after parent has taken all the state info. Must be called 837 * with the proclist lock held, and will release before returning. 838 * 839 * *ru is returned to the caller, and must be freed by the caller. 840 */ 841 static void 842 proc_free(struct proc *p, struct rusage *ru) 843 { 844 struct proc *parent; 845 struct lwp *l; 846 ksiginfo_t ksi; 847 kauth_cred_t cred1, cred2; 848 uid_t uid; 849 850 KASSERT(mutex_owned(proc_lock)); 851 KASSERT(p->p_nlwps == 1); 852 KASSERT(p->p_nzlwps == 1); 853 KASSERT(p->p_nrlwps == 0); 854 KASSERT(p->p_stat == SZOMB); 855 856 /* 857 * If we got the child via ptrace(2) or procfs, and 858 * the parent is different (meaning the process was 859 * attached, rather than run as a child), then we need 860 * to give it back to the old parent, and send the 861 * parent the exit signal. The rest of the cleanup 862 * will be done when the old parent waits on the child. 863 */ 864 if ((p->p_slflag & PSL_TRACED) != 0) { 865 parent = p->p_pptr; 866 if (p->p_opptr != parent){ 867 mutex_enter(p->p_lock); 868 p->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 869 mutex_exit(p->p_lock); 870 parent = p->p_opptr; 871 if (parent == NULL) 872 parent = initproc; 873 proc_reparent(p, parent); 874 p->p_opptr = NULL; 875 if (p->p_exitsig != 0) { 876 exit_psignal(p, parent, &ksi); 877 kpsignal(parent, &ksi, NULL); 878 } 879 cv_broadcast(&parent->p_waitcv); 880 mutex_exit(proc_lock); 881 return; 882 } 883 } 884 885 /* 886 * Finally finished with old proc entry. Unlink it from its process 887 * group. 888 */ 889 leavepgrp(p); 890 891 parent = p->p_pptr; 892 sched_proc_exit(parent, p); 893 894 /* 895 * Add child times of exiting process onto its own times. 896 * This cannot be done any earlier else it might get done twice. 897 */ 898 l = LIST_FIRST(&p->p_lwps); 899 p->p_stats->p_ru.ru_nvcsw += (l->l_ncsw - l->l_nivcsw); 900 p->p_stats->p_ru.ru_nivcsw += l->l_nivcsw; 901 ruadd(&p->p_stats->p_ru, &l->l_ru); 902 ruadd(&p->p_stats->p_ru, &p->p_stats->p_cru); 903 ruadd(&parent->p_stats->p_cru, &p->p_stats->p_ru); 904 if (ru != NULL) 905 *ru = p->p_stats->p_ru; 906 p->p_xstat = 0; 907 908 /* 909 * At this point we are going to start freeing the final resources. 910 * If anyone tries to access the proc structure after here they will 911 * get a shock - bits are missing. Attempt to make it hard! We 912 * don't bother with any further locking past this point. 913 */ 914 p->p_stat = SIDL; /* not even a zombie any more */ 915 LIST_REMOVE(p, p_list); /* off zombproc */ 916 parent = p->p_pptr; 917 p->p_pptr->p_nstopchild--; 918 LIST_REMOVE(p, p_sibling); 919 920 /* 921 * Let pid be reallocated. 922 */ 923 proc_free_pid(p); 924 mutex_exit(proc_lock); 925 926 /* 927 * Delay release until after lwp_free. 928 */ 929 cred2 = l->l_cred; 930 931 /* 932 * Free the last LWP's resources. 933 * 934 * lwp_free ensures the LWP is no longer running on another CPU. 935 */ 936 lwp_free(l, false, true); 937 938 /* 939 * Now no one except us can reach the process p. 940 */ 941 942 /* 943 * Decrement the count of procs running with this uid. 944 */ 945 cred1 = p->p_cred; 946 uid = kauth_cred_getuid(cred1); 947 (void)chgproccnt(uid, -1); 948 949 /* 950 * Release substructures. 951 */ 952 953 limfree(p->p_limit); 954 pstatsfree(p->p_stats); 955 kauth_cred_free(cred1); 956 kauth_cred_free(cred2); 957 958 /* 959 * Release reference to text vnode 960 */ 961 if (p->p_textvp) 962 vrele(p->p_textvp); 963 964 mutex_destroy(&p->p_auxlock); 965 mutex_obj_free(p->p_lock); 966 mutex_destroy(&p->p_stmutex); 967 cv_destroy(&p->p_waitcv); 968 cv_destroy(&p->p_lwpcv); 969 rw_destroy(&p->p_reflock); 970 971 proc_free_mem(p); 972 } 973 974 /* 975 * make process 'parent' the new parent of process 'child'. 976 * 977 * Must be called with proc_lock held. 978 */ 979 void 980 proc_reparent(struct proc *child, struct proc *parent) 981 { 982 983 KASSERT(mutex_owned(proc_lock)); 984 985 if (child->p_pptr == parent) 986 return; 987 988 if (child->p_stat == SZOMB || 989 (child->p_stat == SSTOP && !child->p_waited)) { 990 child->p_pptr->p_nstopchild--; 991 parent->p_nstopchild++; 992 } 993 if (parent == initproc) 994 child->p_exitsig = SIGCHLD; 995 996 LIST_REMOVE(child, p_sibling); 997 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 998 child->p_pptr = parent; 999 } 1000