1 /* $NetBSD: kern_exit.c,v 1.194 2007/11/30 23:05:43 ad Exp $ */ 2 3 /*- 4 * Copyright (c) 1998, 1999, 2006, 2007 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 * 3. All advertising materials mentioning features or use of this software 20 * must display the following acknowledgement: 21 * This product includes software developed by the NetBSD 22 * Foundation, Inc. and its contributors. 23 * 4. Neither the name of The NetBSD Foundation nor the names of its 24 * contributors may be used to endorse or promote products derived 25 * from this software without specific prior written permission. 26 * 27 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 28 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 29 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 30 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 31 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 32 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 33 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 34 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 35 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 36 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 37 * POSSIBILITY OF SUCH DAMAGE. 38 */ 39 40 /* 41 * Copyright (c) 1982, 1986, 1989, 1991, 1993 42 * The Regents of the University of California. All rights reserved. 43 * (c) UNIX System Laboratories, Inc. 44 * All or some portions of this file are derived from material licensed 45 * to the University of California by American Telephone and Telegraph 46 * Co. or Unix System Laboratories, Inc. and are reproduced herein with 47 * the permission of UNIX System Laboratories, Inc. 48 * 49 * Redistribution and use in source and binary forms, with or without 50 * modification, are permitted provided that the following conditions 51 * are met: 52 * 1. Redistributions of source code must retain the above copyright 53 * notice, this list of conditions and the following disclaimer. 54 * 2. Redistributions in binary form must reproduce the above copyright 55 * notice, this list of conditions and the following disclaimer in the 56 * documentation and/or other materials provided with the distribution. 57 * 3. Neither the name of the University nor the names of its contributors 58 * may be used to endorse or promote products derived from this software 59 * without specific prior written permission. 60 * 61 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 62 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 63 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 64 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 65 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 66 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 67 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 68 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 69 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 70 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 71 * SUCH DAMAGE. 72 * 73 * @(#)kern_exit.c 8.10 (Berkeley) 2/23/95 74 */ 75 76 #include <sys/cdefs.h> 77 __KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.194 2007/11/30 23:05:43 ad Exp $"); 78 79 #include "opt_ktrace.h" 80 #include "opt_perfctrs.h" 81 #include "opt_systrace.h" 82 #include "opt_sysv.h" 83 84 #include <sys/param.h> 85 #include <sys/aio.h> 86 #include <sys/systm.h> 87 #include <sys/ioctl.h> 88 #include <sys/tty.h> 89 #include <sys/time.h> 90 #include <sys/resource.h> 91 #include <sys/kernel.h> 92 #include <sys/proc.h> 93 #include <sys/buf.h> 94 #include <sys/wait.h> 95 #include <sys/file.h> 96 #include <sys/vnode.h> 97 #include <sys/syslog.h> 98 #include <sys/malloc.h> 99 #include <sys/pool.h> 100 #include <sys/resourcevar.h> 101 #if defined(PERFCTRS) 102 #include <sys/pmc.h> 103 #endif 104 #include <sys/ptrace.h> 105 #include <sys/acct.h> 106 #include <sys/filedesc.h> 107 #include <sys/ras.h> 108 #include <sys/signalvar.h> 109 #include <sys/sched.h> 110 #include <sys/mount.h> 111 #include <sys/syscallargs.h> 112 #include <sys/systrace.h> 113 #include <sys/kauth.h> 114 #include <sys/sleepq.h> 115 #include <sys/lockdebug.h> 116 #include <sys/ktrace.h> 117 #include <sys/cpu.h> 118 #include <sys/lwpctl.h> 119 #include <sys/atomic.h> 120 121 #include <uvm/uvm_extern.h> 122 123 #define DEBUG_EXIT 124 125 #ifdef DEBUG_EXIT 126 int debug_exit = 0; 127 #define DPRINTF(x) if (debug_exit) printf x 128 #else 129 #define DPRINTF(x) 130 #endif 131 132 static int find_stopped_child(struct proc *, pid_t, int, struct proc **, int *); 133 static void proc_free(struct proc *, struct rusage *); 134 135 /* 136 * Fill in the appropriate signal information, and signal the parent. 137 */ 138 static void 139 exit_psignal(struct proc *p, struct proc *pp, ksiginfo_t *ksi) 140 { 141 142 KSI_INIT(ksi); 143 if ((ksi->ksi_signo = P_EXITSIG(p)) == SIGCHLD) { 144 if (WIFSIGNALED(p->p_xstat)) { 145 if (WCOREDUMP(p->p_xstat)) 146 ksi->ksi_code = CLD_DUMPED; 147 else 148 ksi->ksi_code = CLD_KILLED; 149 } else { 150 ksi->ksi_code = CLD_EXITED; 151 } 152 } 153 /* 154 * We fill those in, even for non-SIGCHLD. 155 * It's safe to access p->p_cred unlocked here. 156 */ 157 ksi->ksi_pid = p->p_pid; 158 ksi->ksi_uid = kauth_cred_geteuid(p->p_cred); 159 ksi->ksi_status = p->p_xstat; 160 /* XXX: is this still valid? */ 161 ksi->ksi_utime = p->p_stats->p_ru.ru_utime.tv_sec; 162 ksi->ksi_stime = p->p_stats->p_ru.ru_stime.tv_sec; 163 } 164 165 /* 166 * exit -- 167 * Death of process. 168 */ 169 int 170 sys_exit(struct lwp *l, void *v, register_t *retval) 171 { 172 struct sys_exit_args /* { 173 syscallarg(int) rval; 174 } */ *uap = v; 175 struct proc *p = l->l_proc; 176 177 /* Don't call exit1() multiple times in the same process. */ 178 mutex_enter(&p->p_smutex); 179 if (p->p_sflag & PS_WEXIT) { 180 mutex_exit(&p->p_smutex); 181 lwp_exit(l); 182 } 183 184 /* exit1() will release the mutex. */ 185 exit1(l, W_EXITCODE(SCARG(uap, rval), 0)); 186 /* NOTREACHED */ 187 return (0); 188 } 189 190 /* 191 * Exit: deallocate address space and other resources, change proc state 192 * to zombie, and unlink proc from allproc and parent's lists. Save exit 193 * status and rusage for wait(). Check for child processes and orphan them. 194 * 195 * Must be called with p->p_smutex held. Does not return. 196 */ 197 void 198 exit1(struct lwp *l, int rv) 199 { 200 struct proc *p, *q, *nq; 201 ksiginfo_t ksi; 202 ksiginfoq_t kq; 203 int wakeinit; 204 205 p = l->l_proc; 206 207 KASSERT(mutex_owned(&p->p_smutex)); 208 209 if (__predict_false(p == initproc)) 210 panic("init died (signal %d, exit %d)", 211 WTERMSIG(rv), WEXITSTATUS(rv)); 212 213 p->p_sflag |= PS_WEXIT; 214 215 /* 216 * Force all other LWPs to exit before we do. Only then can we 217 * begin to tear down the rest of the process state. 218 */ 219 if (p->p_nlwps > 1) 220 exit_lwps(l); 221 222 ksiginfo_queue_init(&kq); 223 224 /* 225 * If we have been asked to stop on exit, do so now. 226 */ 227 if (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 mutex_exit(&p->p_smutex); 237 mi_switch(l); 238 KERNEL_LOCK(l->l_biglocks, l); 239 } else 240 mutex_exit(&p->p_smutex); 241 242 /* Destroy any lwpctl info. */ 243 if (p->p_lwpctl != NULL) 244 lwp_ctl_exit(); 245 246 /* Destroy all AIO works */ 247 aio_exit(p, p->p_aio); 248 249 /* 250 * Drain all remaining references that procfs, ptrace and others may 251 * have on the process. 252 */ 253 rw_enter(&p->p_reflock, RW_WRITER); 254 255 /* 256 * Bin any remaining signals and mark the process as dying so it will 257 * not be found for, e.g. signals. 258 */ 259 mutex_enter(&p->p_smutex); 260 sigfillset(&p->p_sigctx.ps_sigignore); 261 sigclearall(p, NULL, &kq); 262 p->p_stat = SDYING; 263 mutex_exit(&p->p_smutex); 264 ksiginfo_queue_drain(&kq); 265 266 DPRINTF(("exit1: %d.%d exiting.\n", p->p_pid, l->l_lid)); 267 268 #ifdef PGINPROF 269 vmsizmon(); 270 #endif 271 timers_free(p, TIMERS_ALL); 272 #if defined(__HAVE_RAS) 273 ras_purgeall(); 274 #endif 275 276 /* 277 * Close open files, release open-file table and free signal 278 * actions. This may block! 279 */ 280 fdfree(l); 281 cwdfree(p->p_cwdi); 282 p->p_cwdi = NULL; 283 doexithooks(p); 284 sigactsfree(p->p_sigacts); 285 286 /* 287 * Write out accounting data. 288 */ 289 (void)acct_process(l); 290 291 #ifdef KTRACE 292 /* 293 * Release trace file. 294 */ 295 if (p->p_tracep != NULL) { 296 mutex_enter(&ktrace_lock); 297 ktrderef(p); 298 mutex_exit(&ktrace_lock); 299 } 300 #endif 301 #ifdef SYSTRACE 302 systrace_sys_exit(p); 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 /* Collect child u-areas. */ 316 uvm_uarea_drain(false); 317 318 /* 319 * Free the VM resources we're still holding on to. 320 * We must do this from a valid thread because doing 321 * so may block. This frees vmspace, which we don't 322 * need anymore. The only remaining lwp is the one 323 * we run at this moment, nothing runs in userland 324 * anymore. 325 */ 326 uvm_proc_exit(p); 327 328 /* 329 * While we can still block, and mark the LWP as unswappable to 330 * prevent conflicts with the with the swapper. We also shouldn't 331 * be swapped out, because we are about to exit and will release 332 * memory. 333 */ 334 uvm_lwp_hold(l); 335 336 /* 337 * Stop profiling. 338 */ 339 if ((p->p_stflag & PST_PROFIL) != 0) { 340 mutex_spin_enter(&p->p_stmutex); 341 stopprofclock(p); 342 mutex_spin_exit(&p->p_stmutex); 343 } 344 345 /* 346 * If parent is waiting for us to exit or exec, P_PPWAIT is set; we 347 * wake up the parent early to avoid deadlock. We can do this once 348 * the VM resources are released. 349 */ 350 mutex_enter(&proclist_lock); 351 352 mutex_enter(&p->p_smutex); 353 if (p->p_sflag & PS_PPWAIT) { 354 p->p_sflag &= ~PS_PPWAIT; 355 cv_broadcast(&p->p_pptr->p_waitcv); 356 } 357 mutex_exit(&p->p_smutex); 358 359 if (SESS_LEADER(p)) { 360 struct vnode *vprele = NULL, *vprevoke = NULL; 361 struct session *sp = p->p_session; 362 struct tty *tp; 363 364 if (sp->s_ttyvp) { 365 /* 366 * Controlling process. 367 * Signal foreground pgrp, 368 * drain controlling terminal 369 * and revoke access to controlling terminal. 370 */ 371 tp = sp->s_ttyp; 372 mutex_spin_enter(&tty_lock); 373 if (tp->t_session == sp) { 374 if (tp->t_pgrp) { 375 mutex_enter(&proclist_mutex); 376 pgsignal(tp->t_pgrp, SIGHUP, 1); 377 mutex_exit(&proclist_mutex); 378 } 379 /* we can't guarantee the revoke will do this */ 380 tp->t_pgrp = NULL; 381 tp->t_session = NULL; 382 mutex_spin_exit(&tty_lock); 383 SESSRELE(sp); 384 mutex_exit(&proclist_lock); 385 (void) ttywait(tp); 386 mutex_enter(&proclist_lock); 387 388 /* 389 * The tty could have been revoked 390 * if we blocked. 391 */ 392 vprevoke = sp->s_ttyvp; 393 } else 394 mutex_spin_exit(&tty_lock); 395 vprele = sp->s_ttyvp; 396 sp->s_ttyvp = NULL; 397 /* 398 * s_ttyp is not zero'd; we use this to indicate 399 * that the session once had a controlling terminal. 400 * (for logging and informational purposes) 401 */ 402 } 403 sp->s_leader = NULL; 404 405 if (vprevoke != NULL || vprele != NULL) { 406 mutex_exit(&proclist_lock); 407 if (vprevoke != NULL) 408 VOP_REVOKE(vprevoke, REVOKEALL); 409 if (vprele != NULL) 410 vrele(vprele); 411 mutex_enter(&proclist_lock); 412 } 413 } 414 mutex_enter(&proclist_mutex); 415 fixjobc(p, p->p_pgrp, 0); 416 mutex_exit(&proclist_mutex); 417 418 /* 419 * Finalize the last LWP's specificdata, as well as the 420 * specificdata for the proc itself. 421 */ 422 lwp_finispecific(l); 423 proc_finispecific(p); 424 425 /* 426 * Notify interested parties of our demise. 427 */ 428 KNOTE(&p->p_klist, NOTE_EXIT); 429 430 #if PERFCTRS 431 /* 432 * Save final PMC information in parent process & clean up. 433 */ 434 if (PMC_ENABLED(p)) { 435 pmc_save_context(p); 436 pmc_accumulate(p->p_pptr, p); 437 pmc_process_exit(p); 438 } 439 #endif 440 441 /* 442 * Reset p_opptr pointer of all former children which got 443 * traced by another process and were reparented. We reset 444 * it to NULL here; the trace detach code then reparents 445 * the child to initproc. We only check allproc list, since 446 * eventual former children on zombproc list won't reference 447 * p_opptr anymore. 448 */ 449 if (p->p_slflag & PSL_CHTRACED) { 450 PROCLIST_FOREACH(q, &allproc) { 451 if (q->p_opptr == p) 452 q->p_opptr = NULL; 453 } 454 } 455 456 /* 457 * Give orphaned children to init(8). 458 */ 459 q = LIST_FIRST(&p->p_children); 460 wakeinit = (q != NULL); 461 for (; q != NULL; q = nq) { 462 nq = LIST_NEXT(q, p_sibling); 463 464 /* 465 * Traced processes are killed since their existence 466 * means someone is screwing up. Since we reset the 467 * trace flags, the logic in sys_wait4() would not be 468 * triggered to reparent the process to its 469 * original parent, so we must do this here. 470 */ 471 if (q->p_slflag & PSL_TRACED) { 472 mutex_enter(&p->p_smutex); 473 q->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 474 mutex_exit(&p->p_smutex); 475 if (q->p_opptr != q->p_pptr) { 476 struct proc *t = q->p_opptr; 477 proc_reparent(q, t ? t : initproc); 478 q->p_opptr = NULL; 479 } else 480 proc_reparent(q, initproc); 481 killproc(q, "orphaned traced process"); 482 } else 483 proc_reparent(q, initproc); 484 } 485 486 /* 487 * Move proc from allproc to zombproc, it's now nearly ready to be 488 * collected by parent. 489 */ 490 mutex_enter(&proclist_mutex); 491 LIST_REMOVE(l, l_list); 492 LIST_REMOVE(p, p_list); 493 LIST_INSERT_HEAD(&zombproc, p, p_list); 494 495 /* 496 * Mark the process as dead. We must do this before we signal 497 * the parent. 498 */ 499 p->p_stat = SDEAD; 500 501 /* Put in front of parent's sibling list for parent to collect it */ 502 q = p->p_pptr; 503 q->p_nstopchild++; 504 if (LIST_FIRST(&q->p_children) != p) { 505 /* Put child where it can be found quickly */ 506 LIST_REMOVE(p, p_sibling); 507 LIST_INSERT_HEAD(&q->p_children, p, p_sibling); 508 } 509 mutex_exit(&proclist_mutex); 510 511 /* 512 * Notify parent that we're gone. If parent has the P_NOCLDWAIT 513 * flag set, notify init instead (and hope it will handle 514 * this situation). 515 */ 516 mutex_enter(&q->p_mutex); 517 if (q->p_flag & (PK_NOCLDWAIT|PK_CLDSIGIGN)) { 518 proc_reparent(p, initproc); 519 wakeinit = 1; 520 521 /* 522 * If this was the last child of our parent, notify 523 * parent, so in case he was wait(2)ing, he will 524 * continue. 525 */ 526 if (LIST_FIRST(&q->p_children) == NULL) 527 cv_broadcast(&q->p_waitcv); 528 } 529 mutex_exit(&q->p_mutex); 530 531 /* Reload parent pointer, since p may have been reparented above */ 532 q = p->p_pptr; 533 534 if ((p->p_slflag & PSL_FSTRACE) == 0 && p->p_exitsig != 0) { 535 exit_psignal(p, q, &ksi); 536 mutex_enter(&proclist_mutex); 537 kpsignal(q, &ksi, NULL); 538 mutex_exit(&proclist_mutex); 539 } 540 541 /* Calculate the final rusage info. */ 542 calcru(p, &p->p_stats->p_ru.ru_utime, &p->p_stats->p_ru.ru_stime, 543 NULL, NULL); 544 545 if (wakeinit) 546 cv_broadcast(&initproc->p_waitcv); 547 548 callout_destroy(&l->l_timeout_ch); 549 550 /* 551 * Remaining lwp resources will be freed in lwp_exit2() once we've 552 * switch to idle context; at that point, we will be marked as a 553 * full blown zombie. 554 * 555 * XXXSMP disable preemption. 556 */ 557 mutex_enter(&p->p_smutex); 558 lwp_drainrefs(l); 559 lwp_lock(l); 560 l->l_prflag &= ~LPR_DETACHED; 561 l->l_stat = LSZOMB; 562 lwp_unlock(l); 563 KASSERT(curlwp == l); 564 KASSERT(p->p_nrlwps == 1); 565 KASSERT(p->p_nlwps == 1); 566 p->p_stat = SZOMB; 567 p->p_nrlwps--; 568 p->p_nzlwps++; 569 p->p_ndlwps = 0; 570 mutex_exit(&p->p_smutex); 571 572 /* 573 * Signal the parent to collect us, and drop the proclist lock. 574 * Drop debugger/procfs lock; no new references can be gained. 575 */ 576 cv_broadcast(&p->p_pptr->p_waitcv); 577 mutex_exit(&proclist_lock); 578 rw_exit(&p->p_reflock); 579 580 /* Verify that we hold no locks other than the kernel lock. */ 581 #ifdef MULTIPROCESSOR 582 LOCKDEBUG_BARRIER(&kernel_lock, 0); 583 #else 584 LOCKDEBUG_BARRIER(NULL, 0); 585 #endif 586 587 /* 588 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP! 589 */ 590 591 /* 592 * Give machine-dependent code a chance to free any MD LWP 593 * resources. This must be done before uvm_lwp_exit(), in 594 * case these resources are in the PCB. 595 */ 596 #ifndef __NO_CPU_LWP_FREE 597 cpu_lwp_free(l, 1); 598 #endif 599 pmap_deactivate(l); 600 601 /* This process no longer needs to hold the kernel lock. */ 602 #ifdef notyet 603 /* XXXSMP hold in lwp_userret() */ 604 KERNEL_UNLOCK_LAST(l); 605 #else 606 KERNEL_UNLOCK_ALL(l, NULL); 607 #endif 608 609 lwp_exit_switchaway(l); 610 } 611 612 void 613 exit_lwps(struct lwp *l) 614 { 615 struct proc *p; 616 struct lwp *l2; 617 int error; 618 lwpid_t waited; 619 #if defined(MULTIPROCESSOR) 620 int nlocks; 621 #endif 622 623 KERNEL_UNLOCK_ALL(l, &nlocks); 624 625 p = l->l_proc; 626 KASSERT(mutex_owned(&p->p_smutex)); 627 628 retry: 629 /* 630 * Interrupt LWPs in interruptable sleep, unsuspend suspended 631 * LWPs and then wait for everyone else to finish. 632 */ 633 LIST_FOREACH(l2, &p->p_lwps, l_sibling) { 634 if (l2 == l) 635 continue; 636 lwp_lock(l2); 637 l2->l_flag |= LW_WEXIT; 638 if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) || 639 l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) { 640 /* setrunnable() will release the lock. */ 641 setrunnable(l2); 642 DPRINTF(("exit_lwps: Made %d.%d runnable\n", 643 p->p_pid, l2->l_lid)); 644 continue; 645 } 646 lwp_unlock(l2); 647 } 648 while (p->p_nlwps > 1) { 649 DPRINTF(("exit_lwps: waiting for %d LWPs (%d zombies)\n", 650 p->p_nlwps, p->p_nzlwps)); 651 error = lwp_wait1(l, 0, &waited, LWPWAIT_EXITCONTROL); 652 if (p->p_nlwps == 1) 653 break; 654 if (error == EDEADLK) { 655 /* 656 * LWPs can get suspended/slept behind us. 657 * (eg. sa_setwoken) 658 * kick them again and retry. 659 */ 660 goto retry; 661 } 662 if (error) 663 panic("exit_lwps: lwp_wait1 failed with error %d", 664 error); 665 DPRINTF(("exit_lwps: Got LWP %d from lwp_wait1()\n", waited)); 666 } 667 668 #if defined(MULTIPROCESSOR) 669 if (nlocks > 0) { 670 mutex_exit(&p->p_smutex); 671 KERNEL_LOCK(nlocks, l); 672 mutex_enter(&p->p_smutex); 673 } 674 #endif /* defined(MULTIPROCESSOR) */ 675 KASSERT(p->p_nlwps == 1); 676 } 677 678 int 679 do_sys_wait(struct lwp *l, int *pid, int *status, int options, 680 struct rusage *ru, int *was_zombie) 681 { 682 struct proc *child; 683 int error; 684 685 mutex_enter(&proclist_lock); 686 687 error = find_stopped_child(l->l_proc, *pid, options, &child, status); 688 689 if (child == NULL) { 690 mutex_exit(&proclist_lock); 691 *pid = 0; 692 return error; 693 } 694 695 *pid = child->p_pid; 696 697 if (child->p_stat == SZOMB) { 698 /* proc_free() will release the proclist_lock. */ 699 *was_zombie = 1; 700 if (options & WNOWAIT) 701 mutex_exit(&proclist_lock); 702 else { 703 KERNEL_LOCK(1, l); /* XXXSMP */ 704 proc_free(child, ru); 705 KERNEL_UNLOCK_ONE(l); /* XXXSMP */ 706 } 707 } else { 708 /* Child state must have been SSTOP. */ 709 *was_zombie = 0; 710 mutex_exit(&proclist_lock); 711 *status = W_STOPCODE(*status); 712 } 713 714 return 0; 715 } 716 717 int 718 sys_wait4(struct lwp *l, void *v, register_t *retval) 719 { 720 struct sys_wait4_args /* { 721 syscallarg(int) pid; 722 syscallarg(int *) status; 723 syscallarg(int) options; 724 syscallarg(struct rusage *) rusage; 725 } */ *uap = v; 726 int status, error; 727 int was_zombie; 728 struct rusage ru; 729 730 error = do_sys_wait(l, &SCARG(uap, pid), &status, SCARG(uap, options), 731 SCARG(uap, rusage) != NULL ? &ru : NULL, &was_zombie); 732 733 retval[0] = SCARG(uap, pid); 734 if (SCARG(uap, pid) == 0) 735 return error; 736 737 if (SCARG(uap, rusage)) 738 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru)); 739 740 if (error == 0 && SCARG(uap, status)) 741 error = copyout(&status, SCARG(uap, status), sizeof(status)); 742 743 return error; 744 } 745 746 /* 747 * Scan list of child processes for a child process that has stopped or 748 * exited. Used by sys_wait4 and 'compat' equivalents. 749 * 750 * Must be called with the proclist_lock held, and may release 751 * while waiting. 752 */ 753 static int 754 find_stopped_child(struct proc *parent, pid_t pid, int options, 755 struct proc **child_p, int *status_p) 756 { 757 struct proc *child, *dead; 758 int error; 759 760 KASSERT(mutex_owned(&proclist_lock)); 761 762 if (options & ~(WUNTRACED|WNOHANG|WALTSIG|WALLSIG) 763 && !(options & WOPTSCHECKED)) { 764 *child_p = NULL; 765 return EINVAL; 766 } 767 768 if (pid == 0 && !(options & WOPTSCHECKED)) 769 pid = -parent->p_pgid; 770 771 for (;;) { 772 error = ECHILD; 773 dead = NULL; 774 775 mutex_enter(&proclist_mutex); 776 LIST_FOREACH(child, &parent->p_children, p_sibling) { 777 if (pid >= 0) { 778 if (child->p_pid != pid) { 779 child = p_find(pid, PFIND_ZOMBIE | 780 PFIND_LOCKED); 781 if (child == NULL || 782 child->p_pptr != parent) { 783 child = NULL; 784 break; 785 } 786 } 787 } else if (pid != WAIT_ANY && child->p_pgid != -pid) { 788 /* Child not in correct pgrp */ 789 continue; 790 } 791 792 /* 793 * Wait for processes with p_exitsig != SIGCHLD 794 * processes only if WALTSIG is set; wait for 795 * processes with p_exitsig == SIGCHLD only 796 * if WALTSIG is clear. 797 */ 798 if (((options & WALLSIG) == 0) && 799 (options & WALTSIG ? child->p_exitsig == SIGCHLD 800 : P_EXITSIG(child) != SIGCHLD)){ 801 if (child->p_pid == pid) { 802 child = NULL; 803 break; 804 } 805 continue; 806 } 807 808 error = 0; 809 if ((options & WNOZOMBIE) == 0) { 810 if (child->p_stat == SZOMB) 811 break; 812 if (child->p_stat == SDEAD) { 813 /* 814 * We may occasionally arrive here 815 * after receiving a signal, but 816 * immediatley before the child 817 * process is zombified. The wait 818 * will be short, so avoid returning 819 * to userspace. 820 */ 821 dead = child; 822 } 823 } 824 825 if (child->p_stat == SSTOP && 826 child->p_waited == 0 && 827 (child->p_slflag & PSL_TRACED || 828 options & WUNTRACED)) { 829 if ((options & WNOWAIT) == 0) { 830 child->p_waited = 1; 831 parent->p_nstopchild--; 832 } 833 break; 834 } 835 if (parent->p_nstopchild == 0 || child->p_pid == pid) { 836 child = NULL; 837 break; 838 } 839 } 840 841 if (child != NULL || error != 0 || 842 ((options & WNOHANG) != 0 && dead == NULL)) { 843 if (child != NULL) { 844 *status_p = child->p_xstat; 845 } 846 mutex_exit(&proclist_mutex); 847 *child_p = child; 848 return error; 849 } 850 851 /* 852 * Wait for another child process to stop. 853 */ 854 mutex_exit(&proclist_lock); 855 error = cv_wait_sig(&parent->p_waitcv, &proclist_mutex); 856 mutex_exit(&proclist_mutex); 857 mutex_enter(&proclist_lock); 858 859 if (error != 0) { 860 *child_p = NULL; 861 return error; 862 } 863 } 864 } 865 866 /* 867 * Free a process after parent has taken all the state info. Must be called 868 * with the proclist lock held, and will release before returning. 869 * 870 * *ru is returned to the caller, and must be freed by the caller. 871 */ 872 static void 873 proc_free(struct proc *p, struct rusage *ru) 874 { 875 struct proc *parent; 876 struct lwp *l; 877 ksiginfo_t ksi; 878 kauth_cred_t cred1, cred2; 879 uid_t uid; 880 881 KASSERT(mutex_owned(&proclist_lock)); 882 KASSERT(p->p_nlwps == 1); 883 KASSERT(p->p_nzlwps == 1); 884 KASSERT(p->p_nrlwps == 0); 885 KASSERT(p->p_stat == SZOMB); 886 887 /* 888 * If we got the child via ptrace(2) or procfs, and 889 * the parent is different (meaning the process was 890 * attached, rather than run as a child), then we need 891 * to give it back to the old parent, and send the 892 * parent the exit signal. The rest of the cleanup 893 * will be done when the old parent waits on the child. 894 */ 895 if ((p->p_slflag & PSL_TRACED) != 0) { 896 parent = p->p_pptr; 897 if (p->p_opptr != parent){ 898 mutex_enter(&p->p_smutex); 899 p->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL); 900 mutex_exit(&p->p_smutex); 901 parent = p->p_opptr; 902 if (parent == NULL) 903 parent = initproc; 904 proc_reparent(p, parent); 905 p->p_opptr = NULL; 906 if (p->p_exitsig != 0) { 907 exit_psignal(p, parent, &ksi); 908 mutex_enter(&proclist_mutex); 909 kpsignal(parent, &ksi, NULL); 910 mutex_exit(&proclist_mutex); 911 } 912 cv_broadcast(&parent->p_waitcv); 913 mutex_exit(&proclist_lock); 914 return; 915 } 916 } 917 918 /* 919 * Finally finished with old proc entry. Unlink it from its process 920 * group. 921 */ 922 leavepgrp(p); 923 924 parent = p->p_pptr; 925 sched_proc_exit(parent, p); 926 /* 927 * Add child times of exiting process onto its own times. 928 * This cannot be done any earlier else it might get done twice. 929 */ 930 ruadd(&p->p_stats->p_ru, &p->p_stats->p_cru); 931 ruadd(&parent->p_stats->p_cru, &p->p_stats->p_ru); 932 if (ru != NULL) 933 *ru = p->p_stats->p_ru; 934 p->p_xstat = 0; 935 936 /* 937 * At this point we are going to start freeing the final resources. 938 * If anyone tries to access the proc structure after here they will 939 * get a shock - bits are missing. Attempt to make it hard! We 940 * don't bother with any further locking past this point. 941 */ 942 mutex_enter(&proclist_mutex); 943 p->p_stat = SIDL; /* not even a zombie any more */ 944 LIST_REMOVE(p, p_list); /* off zombproc */ 945 parent = p->p_pptr; 946 p->p_pptr->p_nstopchild--; 947 mutex_exit(&proclist_mutex); 948 LIST_REMOVE(p, p_sibling); 949 950 /* 951 * Let pid be reallocated. 952 */ 953 proc_free_pid(p); 954 mutex_exit(&proclist_lock); 955 956 l = LIST_FIRST(&p->p_lwps); 957 958 /* 959 * Delay release until after lwp_free. 960 */ 961 cred2 = l->l_cred; 962 963 /* 964 * Free the last LWP's resources. 965 * 966 * lwp_free ensures the LWP is no longer running on another CPU. 967 */ 968 lwp_free(l, false, true); 969 970 /* 971 * Now no one except us can reach the process p. 972 */ 973 974 /* 975 * Decrement the count of procs running with this uid. 976 */ 977 cred1 = p->p_cred; 978 uid = kauth_cred_getuid(cred1); 979 (void)chgproccnt(uid, -1); 980 981 /* 982 * Release substructures. 983 */ 984 985 limfree(p->p_limit); 986 pstatsfree(p->p_stats); 987 kauth_cred_free(cred1); 988 kauth_cred_free(cred2); 989 990 /* 991 * Release reference to text vnode 992 */ 993 if (p->p_textvp) 994 vrele(p->p_textvp); 995 996 mutex_destroy(&p->p_raslock); 997 mutex_destroy(&p->p_mutex); 998 mutex_destroy(&p->p_stmutex); 999 mutex_destroy(&p->p_smutex); 1000 cv_destroy(&p->p_waitcv); 1001 cv_destroy(&p->p_lwpcv); 1002 rw_destroy(&p->p_reflock); 1003 1004 pool_put(&proc_pool, p); 1005 1006 /* 1007 * Collect child u-areas. 1008 */ 1009 uvm_uarea_drain(false); 1010 } 1011 1012 /* 1013 * make process 'parent' the new parent of process 'child'. 1014 * 1015 * Must be called with proclist_lock lock held. 1016 */ 1017 void 1018 proc_reparent(struct proc *child, struct proc *parent) 1019 { 1020 1021 KASSERT(mutex_owned(&proclist_lock)); 1022 1023 if (child->p_pptr == parent) 1024 return; 1025 1026 mutex_enter(&proclist_mutex); 1027 if (child->p_stat == SZOMB || 1028 (child->p_stat == SSTOP && !child->p_waited)) { 1029 child->p_pptr->p_nstopchild--; 1030 parent->p_nstopchild++; 1031 } 1032 mutex_exit(&proclist_mutex); 1033 if (parent == initproc) 1034 child->p_exitsig = SIGCHLD; 1035 1036 LIST_REMOVE(child, p_sibling); 1037 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling); 1038 child->p_pptr = parent; 1039 } 1040