kern_exit.c revision 1.211 1 /* $NetBSD: kern_exit.c,v 1.211 2008/06/16 09:51:14 ad 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 1.211 2008/06/16 09:51:14 ad 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 (__predict_false(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 mutex_enter(p->p_lock);
232 }
233
234 /*
235 * Bin any remaining signals and mark the process as dying so it will
236 * not be found for, e.g. signals.
237 */
238 sigfillset(&p->p_sigctx.ps_sigignore);
239 sigclearall(p, NULL, &kq);
240 p->p_stat = SDYING;
241 mutex_exit(p->p_lock);
242 ksiginfo_queue_drain(&kq);
243
244 /* Destroy any lwpctl info. */
245 if (p->p_lwpctl != NULL)
246 lwp_ctl_exit();
247
248 /* Destroy all AIO works */
249 aio_exit(p, p->p_aio);
250
251 /*
252 * Drain all remaining references that procfs, ptrace and others may
253 * have on the process.
254 */
255 rw_enter(&p->p_reflock, RW_WRITER);
256
257 DPRINTF(("exit1: %d.%d exiting.\n", p->p_pid, l->l_lid));
258
259 timers_free(p, TIMERS_ALL);
260 #if defined(__HAVE_RAS)
261 ras_purgeall();
262 #endif
263
264 /*
265 * Close open files, release open-file table and free signal
266 * actions. This may block!
267 */
268 fd_free();
269 cwdfree(p->p_cwdi);
270 p->p_cwdi = NULL;
271 doexithooks(p);
272 sigactsfree(p->p_sigacts);
273
274 /*
275 * Write out accounting data.
276 */
277 (void)acct_process(l);
278
279 #ifdef KTRACE
280 /*
281 * Release trace file.
282 */
283 if (p->p_tracep != NULL) {
284 mutex_enter(&ktrace_lock);
285 ktrderef(p);
286 mutex_exit(&ktrace_lock);
287 }
288 #endif
289
290 /*
291 * If emulation has process exit hook, call it now.
292 * Set the exit status now so that the exit hook has
293 * an opportunity to tweak it (COMPAT_LINUX requires
294 * this for thread group emulation)
295 */
296 p->p_xstat = rv;
297 if (p->p_emul->e_proc_exit)
298 (*p->p_emul->e_proc_exit)(p);
299
300 /*
301 * Free the VM resources we're still holding on to.
302 * We must do this from a valid thread because doing
303 * so may block. This frees vmspace, which we don't
304 * need anymore. The only remaining lwp is the one
305 * we run at this moment, nothing runs in userland
306 * anymore.
307 */
308 uvm_proc_exit(p);
309
310 /*
311 * Stop profiling.
312 */
313 if (__predict_false((p->p_stflag & PST_PROFIL) != 0)) {
314 mutex_spin_enter(&p->p_stmutex);
315 stopprofclock(p);
316 mutex_spin_exit(&p->p_stmutex);
317 }
318
319 /*
320 * If parent is waiting for us to exit or exec, P_PPWAIT is set; we
321 * wake up the parent early to avoid deadlock. We can do this once
322 * the VM resources are released.
323 */
324 mutex_enter(proc_lock);
325 if (p->p_lflag & PL_PPWAIT) {
326 p->p_lflag &= ~PL_PPWAIT;
327 cv_broadcast(&p->p_pptr->p_waitcv);
328 }
329
330 if (SESS_LEADER(p)) {
331 struct vnode *vprele = NULL, *vprevoke = NULL;
332 struct session *sp = p->p_session;
333 struct tty *tp;
334
335 if (sp->s_ttyvp) {
336 /*
337 * Controlling process.
338 * Signal foreground pgrp,
339 * drain controlling terminal
340 * and revoke access to controlling terminal.
341 */
342 tp = sp->s_ttyp;
343 mutex_spin_enter(&tty_lock);
344 if (tp->t_session == sp) {
345 /* we can't guarantee the revoke will do this */
346 pgrp = tp->t_pgrp;
347 tp->t_pgrp = NULL;
348 tp->t_session = NULL;
349 mutex_spin_exit(&tty_lock);
350 if (pgrp != NULL) {
351 pgsignal(pgrp, SIGHUP, 1);
352 }
353 mutex_exit(proc_lock);
354 (void) ttywait(tp);
355 mutex_enter(proc_lock);
356
357 /* The tty could have been revoked. */
358 vprevoke = sp->s_ttyvp;
359 } else
360 mutex_spin_exit(&tty_lock);
361 vprele = sp->s_ttyvp;
362 sp->s_ttyvp = NULL;
363 /*
364 * s_ttyp is not zero'd; we use this to indicate
365 * that the session once had a controlling terminal.
366 * (for logging and informational purposes)
367 */
368 }
369 sp->s_leader = NULL;
370
371 if (vprevoke != NULL || vprele != NULL) {
372 if (vprevoke != NULL) {
373 SESSRELE(sp);
374 mutex_exit(proc_lock);
375 VOP_REVOKE(vprevoke, REVOKEALL);
376 } else
377 mutex_exit(proc_lock);
378 if (vprele != NULL)
379 vrele(vprele);
380 mutex_enter(proc_lock);
381 }
382 }
383 fixjobc(p, p->p_pgrp, 0);
384
385 /*
386 * Finalize the last LWP's specificdata, as well as the
387 * specificdata for the proc itself.
388 */
389 lwp_finispecific(l);
390 proc_finispecific(p);
391
392 /*
393 * Notify interested parties of our demise.
394 */
395 KNOTE(&p->p_klist, NOTE_EXIT);
396
397 #if PERFCTRS
398 /*
399 * Save final PMC information in parent process & clean up.
400 */
401 if (PMC_ENABLED(p)) {
402 pmc_save_context(p);
403 pmc_accumulate(p->p_pptr, p);
404 pmc_process_exit(p);
405 }
406 #endif
407
408 /*
409 * Reset p_opptr pointer of all former children which got
410 * traced by another process and were reparented. We reset
411 * it to NULL here; the trace detach code then reparents
412 * the child to initproc. We only check allproc list, since
413 * eventual former children on zombproc list won't reference
414 * p_opptr anymore.
415 */
416 if (__predict_false(p->p_slflag & PSL_CHTRACED)) {
417 PROCLIST_FOREACH(q, &allproc) {
418 if ((q->p_flag & PK_MARKER) != 0)
419 continue;
420 if (q->p_opptr == p)
421 q->p_opptr = NULL;
422 }
423 }
424
425 /*
426 * Give orphaned children to init(8).
427 */
428 q = LIST_FIRST(&p->p_children);
429 wakeinit = (q != NULL);
430 for (; q != NULL; q = nq) {
431 nq = LIST_NEXT(q, p_sibling);
432
433 /*
434 * Traced processes are killed since their existence
435 * means someone is screwing up. Since we reset the
436 * trace flags, the logic in sys_wait4() would not be
437 * triggered to reparent the process to its
438 * original parent, so we must do this here.
439 */
440 if (__predict_false(q->p_slflag & PSL_TRACED)) {
441 mutex_enter(p->p_lock);
442 q->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL);
443 mutex_exit(p->p_lock);
444 if (q->p_opptr != q->p_pptr) {
445 struct proc *t = q->p_opptr;
446 proc_reparent(q, t ? t : initproc);
447 q->p_opptr = NULL;
448 } else
449 proc_reparent(q, initproc);
450 killproc(q, "orphaned traced process");
451 } else
452 proc_reparent(q, initproc);
453 }
454
455 /*
456 * Move proc from allproc to zombproc, it's now nearly ready to be
457 * collected by parent.
458 */
459 LIST_REMOVE(l, l_list);
460 LIST_REMOVE(p, p_list);
461 LIST_INSERT_HEAD(&zombproc, p, p_list);
462
463 /*
464 * Mark the process as dead. We must do this before we signal
465 * the parent.
466 */
467 p->p_stat = SDEAD;
468
469 /* Put in front of parent's sibling list for parent to collect it */
470 q = p->p_pptr;
471 q->p_nstopchild++;
472 if (LIST_FIRST(&q->p_children) != p) {
473 /* Put child where it can be found quickly */
474 LIST_REMOVE(p, p_sibling);
475 LIST_INSERT_HEAD(&q->p_children, p, p_sibling);
476 }
477
478 /*
479 * Notify parent that we're gone. If parent has the P_NOCLDWAIT
480 * flag set, notify init instead (and hope it will handle
481 * this situation).
482 */
483 if (q->p_flag & (PK_NOCLDWAIT|PK_CLDSIGIGN)) {
484 proc_reparent(p, initproc);
485 wakeinit = 1;
486
487 /*
488 * If this was the last child of our parent, notify
489 * parent, so in case he was wait(2)ing, he will
490 * continue.
491 */
492 if (LIST_FIRST(&q->p_children) == NULL)
493 cv_broadcast(&q->p_waitcv);
494 }
495
496 /* Reload parent pointer, since p may have been reparented above */
497 q = p->p_pptr;
498
499 if (__predict_false((p->p_slflag & PSL_FSTRACE) == 0 && p->p_exitsig != 0)) {
500 exit_psignal(p, q, &ksi);
501 kpsignal(q, &ksi, NULL);
502 }
503
504 /* Calculate the final rusage info. */
505 calcru(p, &p->p_stats->p_ru.ru_utime, &p->p_stats->p_ru.ru_stime,
506 NULL, NULL);
507
508 if (wakeinit)
509 cv_broadcast(&initproc->p_waitcv);
510
511 callout_destroy(&l->l_timeout_ch);
512
513 /*
514 * Remaining lwp resources will be freed in lwp_exit2() once we've
515 * switch to idle context; at that point, we will be marked as a
516 * full blown zombie.
517 */
518 mutex_enter(p->p_lock);
519 lwp_drainrefs(l);
520 lwp_lock(l);
521 l->l_prflag &= ~LPR_DETACHED;
522 l->l_stat = LSZOMB;
523 lwp_unlock(l);
524 KASSERT(curlwp == l);
525 KASSERT(p->p_nrlwps == 1);
526 KASSERT(p->p_nlwps == 1);
527 p->p_stat = SZOMB;
528 p->p_nrlwps--;
529 p->p_nzlwps++;
530 p->p_ndlwps = 0;
531 mutex_exit(p->p_lock);
532
533 /*
534 * Signal the parent to collect us, and drop the proclist lock.
535 * Drop debugger/procfs lock; no new references can be gained.
536 */
537 cv_broadcast(&p->p_pptr->p_waitcv);
538 mutex_exit(proc_lock);
539 rw_exit(&p->p_reflock);
540
541 /* Verify that we hold no locks other than the kernel lock. */
542 LOCKDEBUG_BARRIER(&kernel_lock, 0);
543
544 /*
545 * NOTE: WE ARE NO LONGER ALLOWED TO SLEEP!
546 */
547
548 /*
549 * Give machine-dependent code a chance to free any MD LWP
550 * resources. This must be done before uvm_lwp_exit(), in
551 * case these resources are in the PCB.
552 */
553 #ifndef __NO_CPU_LWP_FREE
554 cpu_lwp_free(l, 1);
555 #endif
556 pmap_deactivate(l);
557
558 /* This process no longer needs to hold the kernel lock. */
559 #ifdef notyet
560 /* XXXSMP hold in lwp_userret() */
561 KERNEL_UNLOCK_LAST(l);
562 #else
563 KERNEL_UNLOCK_ALL(l, NULL);
564 #endif
565
566 lwp_exit_switchaway(l);
567 }
568
569 void
570 exit_lwps(struct lwp *l)
571 {
572 struct proc *p;
573 struct lwp *l2;
574 int error;
575 lwpid_t waited;
576 int nlocks;
577
578 KERNEL_UNLOCK_ALL(l, &nlocks);
579
580 p = l->l_proc;
581 KASSERT(mutex_owned(p->p_lock));
582
583 retry:
584 /*
585 * Interrupt LWPs in interruptable sleep, unsuspend suspended
586 * LWPs and then wait for everyone else to finish.
587 */
588 LIST_FOREACH(l2, &p->p_lwps, l_sibling) {
589 if (l2 == l)
590 continue;
591 lwp_lock(l2);
592 l2->l_flag |= LW_WEXIT;
593 if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) ||
594 l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) {
595 /* setrunnable() will release the lock. */
596 setrunnable(l2);
597 DPRINTF(("exit_lwps: Made %d.%d runnable\n",
598 p->p_pid, l2->l_lid));
599 continue;
600 }
601 lwp_unlock(l2);
602 }
603 while (p->p_nlwps > 1) {
604 DPRINTF(("exit_lwps: waiting for %d LWPs (%d zombies)\n",
605 p->p_nlwps, p->p_nzlwps));
606 error = lwp_wait1(l, 0, &waited, LWPWAIT_EXITCONTROL);
607 if (p->p_nlwps == 1)
608 break;
609 if (error == EDEADLK) {
610 /*
611 * LWPs can get suspended/slept behind us.
612 * (eg. sa_setwoken)
613 * kick them again and retry.
614 */
615 goto retry;
616 }
617 if (error)
618 panic("exit_lwps: lwp_wait1 failed with error %d",
619 error);
620 DPRINTF(("exit_lwps: Got LWP %d from lwp_wait1()\n", waited));
621 }
622
623 KERNEL_LOCK(nlocks, l);
624 KASSERT(p->p_nlwps == 1);
625 }
626
627 int
628 do_sys_wait(struct lwp *l, int *pid, int *status, int options,
629 struct rusage *ru, int *was_zombie)
630 {
631 struct proc *child;
632 int error;
633
634 mutex_enter(proc_lock);
635 error = find_stopped_child(l->l_proc, *pid, options, &child, status);
636
637 if (child == NULL) {
638 mutex_exit(proc_lock);
639 *pid = 0;
640 return error;
641 }
642
643 *pid = child->p_pid;
644
645 if (child->p_stat == SZOMB) {
646 /* proc_free() will release the proc_lock. */
647 *was_zombie = 1;
648 if (options & WNOWAIT)
649 mutex_exit(proc_lock);
650 else {
651 proc_free(child, ru);
652 }
653 } else {
654 /* Child state must have been SSTOP. */
655 *was_zombie = 0;
656 mutex_exit(proc_lock);
657 *status = W_STOPCODE(*status);
658 }
659
660 return 0;
661 }
662
663 int
664 sys_wait4(struct lwp *l, const struct sys_wait4_args *uap, register_t *retval)
665 {
666 /* {
667 syscallarg(int) pid;
668 syscallarg(int *) status;
669 syscallarg(int) options;
670 syscallarg(struct rusage *) rusage;
671 } */
672 int status, error;
673 int was_zombie;
674 struct rusage ru;
675 int pid = SCARG(uap, pid);
676
677 error = do_sys_wait(l, &pid, &status, SCARG(uap, options),
678 SCARG(uap, rusage) != NULL ? &ru : NULL, &was_zombie);
679
680 retval[0] = pid;
681 if (pid == 0)
682 return error;
683
684 if (SCARG(uap, rusage))
685 error = copyout(&ru, SCARG(uap, rusage), sizeof(ru));
686
687 if (error == 0 && SCARG(uap, status))
688 error = copyout(&status, SCARG(uap, status), sizeof(status));
689
690 return error;
691 }
692
693 /*
694 * Scan list of child processes for a child process that has stopped or
695 * exited. Used by sys_wait4 and 'compat' equivalents.
696 *
697 * Must be called with the proc_lock held, and may release while waiting.
698 */
699 static int
700 find_stopped_child(struct proc *parent, pid_t pid, int options,
701 struct proc **child_p, int *status_p)
702 {
703 struct proc *child, *dead;
704 int error;
705
706 KASSERT(mutex_owned(proc_lock));
707
708 if (options & ~(WUNTRACED|WNOHANG|WALTSIG|WALLSIG)
709 && !(options & WOPTSCHECKED)) {
710 *child_p = NULL;
711 return EINVAL;
712 }
713
714 if (pid == 0 && !(options & WOPTSCHECKED))
715 pid = -parent->p_pgid;
716
717 for (;;) {
718 error = ECHILD;
719 dead = NULL;
720
721 LIST_FOREACH(child, &parent->p_children, p_sibling) {
722 if (pid >= 0) {
723 if (child->p_pid != pid) {
724 child = p_find(pid, PFIND_ZOMBIE |
725 PFIND_LOCKED);
726 if (child == NULL ||
727 child->p_pptr != parent) {
728 child = NULL;
729 break;
730 }
731 }
732 } else if (pid != WAIT_ANY && child->p_pgid != -pid) {
733 /* Child not in correct pgrp */
734 continue;
735 }
736
737 /*
738 * Wait for processes with p_exitsig != SIGCHLD
739 * processes only if WALTSIG is set; wait for
740 * processes with p_exitsig == SIGCHLD only
741 * if WALTSIG is clear.
742 */
743 if (((options & WALLSIG) == 0) &&
744 (options & WALTSIG ? child->p_exitsig == SIGCHLD
745 : P_EXITSIG(child) != SIGCHLD)){
746 if (child->p_pid == pid) {
747 child = NULL;
748 break;
749 }
750 continue;
751 }
752
753 error = 0;
754 if ((options & WNOZOMBIE) == 0) {
755 if (child->p_stat == SZOMB)
756 break;
757 if (child->p_stat == SDEAD) {
758 /*
759 * We may occasionally arrive here
760 * after receiving a signal, but
761 * immediatley before the child
762 * process is zombified. The wait
763 * will be short, so avoid returning
764 * to userspace.
765 */
766 dead = child;
767 }
768 }
769
770 if (child->p_stat == SSTOP &&
771 child->p_waited == 0 &&
772 (child->p_slflag & PSL_TRACED ||
773 options & WUNTRACED)) {
774 if ((options & WNOWAIT) == 0) {
775 child->p_waited = 1;
776 parent->p_nstopchild--;
777 }
778 break;
779 }
780 if (parent->p_nstopchild == 0 || child->p_pid == pid) {
781 child = NULL;
782 break;
783 }
784 }
785
786 if (child != NULL || error != 0 ||
787 ((options & WNOHANG) != 0 && dead == NULL)) {
788 if (child != NULL) {
789 *status_p = child->p_xstat;
790 }
791 *child_p = child;
792 return error;
793 }
794
795 /*
796 * Wait for another child process to stop.
797 */
798 error = cv_wait_sig(&parent->p_waitcv, proc_lock);
799
800 if (error != 0) {
801 *child_p = NULL;
802 return error;
803 }
804 }
805 }
806
807 /*
808 * Free a process after parent has taken all the state info. Must be called
809 * with the proclist lock held, and will release before returning.
810 *
811 * *ru is returned to the caller, and must be freed by the caller.
812 */
813 static void
814 proc_free(struct proc *p, struct rusage *ru)
815 {
816 struct proc *parent;
817 struct lwp *l;
818 ksiginfo_t ksi;
819 kauth_cred_t cred1, cred2;
820 uid_t uid;
821
822 KASSERT(mutex_owned(proc_lock));
823 KASSERT(p->p_nlwps == 1);
824 KASSERT(p->p_nzlwps == 1);
825 KASSERT(p->p_nrlwps == 0);
826 KASSERT(p->p_stat == SZOMB);
827
828 /*
829 * If we got the child via ptrace(2) or procfs, and
830 * the parent is different (meaning the process was
831 * attached, rather than run as a child), then we need
832 * to give it back to the old parent, and send the
833 * parent the exit signal. The rest of the cleanup
834 * will be done when the old parent waits on the child.
835 */
836 if ((p->p_slflag & PSL_TRACED) != 0) {
837 parent = p->p_pptr;
838 if (p->p_opptr != parent){
839 mutex_enter(p->p_lock);
840 p->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL);
841 mutex_exit(p->p_lock);
842 parent = p->p_opptr;
843 if (parent == NULL)
844 parent = initproc;
845 proc_reparent(p, parent);
846 p->p_opptr = NULL;
847 if (p->p_exitsig != 0) {
848 exit_psignal(p, parent, &ksi);
849 kpsignal(parent, &ksi, NULL);
850 }
851 cv_broadcast(&parent->p_waitcv);
852 mutex_exit(proc_lock);
853 return;
854 }
855 }
856
857 /*
858 * Finally finished with old proc entry. Unlink it from its process
859 * group.
860 */
861 leavepgrp(p);
862
863 parent = p->p_pptr;
864 sched_proc_exit(parent, p);
865
866 /*
867 * Add child times of exiting process onto its own times.
868 * This cannot be done any earlier else it might get done twice.
869 */
870 l = LIST_FIRST(&p->p_lwps);
871 p->p_stats->p_ru.ru_nvcsw += (l->l_ncsw - l->l_nivcsw);
872 p->p_stats->p_ru.ru_nivcsw += l->l_nivcsw;
873 ruadd(&p->p_stats->p_ru, &l->l_ru);
874 ruadd(&p->p_stats->p_ru, &p->p_stats->p_cru);
875 ruadd(&parent->p_stats->p_cru, &p->p_stats->p_ru);
876 if (ru != NULL)
877 *ru = p->p_stats->p_ru;
878 p->p_xstat = 0;
879
880 /*
881 * At this point we are going to start freeing the final resources.
882 * If anyone tries to access the proc structure after here they will
883 * get a shock - bits are missing. Attempt to make it hard! We
884 * don't bother with any further locking past this point.
885 */
886 p->p_stat = SIDL; /* not even a zombie any more */
887 LIST_REMOVE(p, p_list); /* off zombproc */
888 parent = p->p_pptr;
889 p->p_pptr->p_nstopchild--;
890 LIST_REMOVE(p, p_sibling);
891
892 /*
893 * Let pid be reallocated.
894 */
895 proc_free_pid(p);
896 mutex_exit(proc_lock);
897
898 /*
899 * Delay release until after lwp_free.
900 */
901 cred2 = l->l_cred;
902
903 /*
904 * Free the last LWP's resources.
905 *
906 * lwp_free ensures the LWP is no longer running on another CPU.
907 */
908 lwp_free(l, false, true);
909
910 /*
911 * Now no one except us can reach the process p.
912 */
913
914 /*
915 * Decrement the count of procs running with this uid.
916 */
917 cred1 = p->p_cred;
918 uid = kauth_cred_getuid(cred1);
919 (void)chgproccnt(uid, -1);
920
921 /*
922 * Release substructures.
923 */
924
925 limfree(p->p_limit);
926 pstatsfree(p->p_stats);
927 kauth_cred_free(cred1);
928 kauth_cred_free(cred2);
929
930 /*
931 * Release reference to text vnode
932 */
933 if (p->p_textvp)
934 vrele(p->p_textvp);
935
936 mutex_destroy(&p->p_auxlock);
937 mutex_obj_free(p->p_lock);
938 mutex_destroy(&p->p_stmutex);
939 cv_destroy(&p->p_waitcv);
940 cv_destroy(&p->p_lwpcv);
941 rw_destroy(&p->p_reflock);
942
943 proc_free_mem(p);
944 }
945
946 /*
947 * make process 'parent' the new parent of process 'child'.
948 *
949 * Must be called with proc_lock held.
950 */
951 void
952 proc_reparent(struct proc *child, struct proc *parent)
953 {
954
955 KASSERT(mutex_owned(proc_lock));
956
957 if (child->p_pptr == parent)
958 return;
959
960 if (child->p_stat == SZOMB ||
961 (child->p_stat == SSTOP && !child->p_waited)) {
962 child->p_pptr->p_nstopchild--;
963 parent->p_nstopchild++;
964 }
965 if (parent == initproc)
966 child->p_exitsig = SIGCHLD;
967
968 LIST_REMOVE(child, p_sibling);
969 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
970 child->p_pptr = parent;
971 child->p_ppid = parent->p_pid;
972 }
973