FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exit.c
1 /*-
2 * Copyright (c) 1982, 1986, 1989, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
6 * to the University of California by American Telephone and Telegraph
7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
8 * the permission of UNIX System Laboratories, Inc.
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 4. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * @(#)kern_exit.c 8.7 (Berkeley) 2/12/94
35 */
36
37 #include <sys/cdefs.h>
38 __FBSDID("$FreeBSD: src/sys/kern/kern_exit.c,v 1.312 2008/08/20 08:31:58 ed Exp $");
39
40 #include "opt_compat.h"
41 #include "opt_kdtrace.h"
42 #include "opt_ktrace.h"
43 #include "opt_mac.h"
44
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/sysproto.h>
48 #include <sys/eventhandler.h>
49 #include <sys/kernel.h>
50 #include <sys/malloc.h>
51 #include <sys/lock.h>
52 #include <sys/mutex.h>
53 #include <sys/proc.h>
54 #include <sys/pioctl.h>
55 #include <sys/tty.h>
56 #include <sys/wait.h>
57 #include <sys/vmmeter.h>
58 #include <sys/vnode.h>
59 #include <sys/resourcevar.h>
60 #include <sys/sbuf.h>
61 #include <sys/signalvar.h>
62 #include <sys/sched.h>
63 #include <sys/sx.h>
64 #include <sys/syscallsubr.h>
65 #include <sys/syslog.h>
66 #include <sys/ptrace.h>
67 #include <sys/acct.h> /* for acct_process() function prototype */
68 #include <sys/filedesc.h>
69 #include <sys/sdt.h>
70 #include <sys/shm.h>
71 #include <sys/sem.h>
72 #ifdef KTRACE
73 #include <sys/ktrace.h>
74 #endif
75
76 #include <security/audit/audit.h>
77 #include <security/mac/mac_framework.h>
78
79 #include <vm/vm.h>
80 #include <vm/vm_extern.h>
81 #include <vm/vm_param.h>
82 #include <vm/pmap.h>
83 #include <vm/vm_map.h>
84 #include <vm/vm_page.h>
85 #include <vm/uma.h>
86
87 #ifdef KDTRACE_HOOKS
88 #include <sys/dtrace_bsd.h>
89 dtrace_execexit_func_t dtrace_fasttrap_exit;
90 #endif
91
92 SDT_PROVIDER_DECLARE(proc);
93 SDT_PROBE_DEFINE(proc, kernel, , exit);
94 SDT_PROBE_ARGTYPE(proc, kernel, , exit, 0, "int");
95
96 /* Required to be non-static for SysVR4 emulator */
97 MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status");
98
99 /* Hook for NFS teardown procedure. */
100 void (*nlminfo_release_p)(struct proc *p);
101
102 /*
103 * exit -- death of process.
104 */
105 void
106 sys_exit(struct thread *td, struct sys_exit_args *uap)
107 {
108
109 exit1(td, W_EXITCODE(uap->rval, 0));
110 /* NOTREACHED */
111 }
112
113 /*
114 * Exit: deallocate address space and other resources, change proc state to
115 * zombie, and unlink proc from allproc and parent's lists. Save exit status
116 * and rusage for wait(). Check for child processes and orphan them.
117 */
118 void
119 exit1(struct thread *td, int rv)
120 {
121 struct proc *p, *nq, *q;
122 struct vnode *vtmp;
123 struct vnode *ttyvp = NULL;
124 #ifdef KTRACE
125 struct vnode *tracevp;
126 struct ucred *tracecred;
127 #endif
128 struct plimit *plim;
129 int locked;
130
131 mtx_assert(&Giant, MA_NOTOWNED);
132
133 p = td->td_proc;
134 if (p == initproc) {
135 printf("init died (signal %d, exit %d)\n",
136 WTERMSIG(rv), WEXITSTATUS(rv));
137 panic("Going nowhere without my init!");
138 }
139
140 /*
141 * MUST abort all other threads before proceeding past here.
142 */
143 PROC_LOCK(p);
144 while (p->p_flag & P_HADTHREADS) {
145 /*
146 * First check if some other thread got here before us..
147 * if so, act apropriatly, (exit or suspend);
148 */
149 thread_suspend_check(0);
150
151 /*
152 * Kill off the other threads. This requires
153 * some co-operation from other parts of the kernel
154 * so it may not be instantaneous. With this state set
155 * any thread entering the kernel from userspace will
156 * thread_exit() in trap(). Any thread attempting to
157 * sleep will return immediately with EINTR or EWOULDBLOCK
158 * which will hopefully force them to back out to userland
159 * freeing resources as they go. Any thread attempting
160 * to return to userland will thread_exit() from userret().
161 * thread_exit() will unsuspend us when the last of the
162 * other threads exits.
163 * If there is already a thread singler after resumption,
164 * calling thread_single will fail; in that case, we just
165 * re-check all suspension request, the thread should
166 * either be suspended there or exit.
167 */
168 if (! thread_single(SINGLE_EXIT))
169 break;
170
171 /*
172 * All other activity in this process is now stopped.
173 * Threading support has been turned off.
174 */
175 }
176 KASSERT(p->p_numthreads == 1,
177 ("exit1: proc %p exiting with %d threads", p, p->p_numthreads));
178 /*
179 * Wakeup anyone in procfs' PIOCWAIT. They should have a hold
180 * on our vmspace, so we should block below until they have
181 * released their reference to us. Note that if they have
182 * requested S_EXIT stops we will block here until they ack
183 * via PIOCCONT.
184 */
185 _STOPEVENT(p, S_EXIT, rv);
186
187 /*
188 * Note that we are exiting and do another wakeup of anyone in
189 * PIOCWAIT in case they aren't listening for S_EXIT stops or
190 * decided to wait again after we told them we are exiting.
191 */
192 p->p_flag |= P_WEXIT;
193 wakeup(&p->p_stype);
194
195 /*
196 * Wait for any processes that have a hold on our vmspace to
197 * release their reference.
198 */
199 while (p->p_lock > 0)
200 msleep(&p->p_lock, &p->p_mtx, PWAIT, "exithold", 0);
201
202 PROC_UNLOCK(p);
203 /* Drain the limit callout while we don't have the proc locked */
204 callout_drain(&p->p_limco);
205
206 #ifdef AUDIT
207 /*
208 * The Sun BSM exit token contains two components: an exit status as
209 * passed to exit(), and a return value to indicate what sort of exit
210 * it was. The exit status is WEXITSTATUS(rv), but it's not clear
211 * what the return value is.
212 */
213 AUDIT_ARG(exit, WEXITSTATUS(rv), 0);
214 AUDIT_SYSCALL_EXIT(0, td);
215 #endif
216
217 /* Are we a task leader? */
218 if (p == p->p_leader) {
219 mtx_lock(&ppeers_lock);
220 q = p->p_peers;
221 while (q != NULL) {
222 PROC_LOCK(q);
223 psignal(q, SIGKILL);
224 PROC_UNLOCK(q);
225 q = q->p_peers;
226 }
227 while (p->p_peers != NULL)
228 msleep(p, &ppeers_lock, PWAIT, "exit1", 0);
229 mtx_unlock(&ppeers_lock);
230 }
231
232 /*
233 * Check if any loadable modules need anything done at process exit.
234 * E.g. SYSV IPC stuff
235 * XXX what if one of these generates an error?
236 */
237 EVENTHANDLER_INVOKE(process_exit, p);
238
239 /*
240 * If parent is waiting for us to exit or exec,
241 * P_PPWAIT is set; we will wakeup the parent below.
242 */
243 PROC_LOCK(p);
244 stopprofclock(p);
245 p->p_flag &= ~(P_TRACED | P_PPWAIT);
246
247 /*
248 * Stop the real interval timer. If the handler is currently
249 * executing, prevent it from rearming itself and let it finish.
250 */
251 if (timevalisset(&p->p_realtimer.it_value) &&
252 callout_stop(&p->p_itcallout) == 0) {
253 timevalclear(&p->p_realtimer.it_interval);
254 msleep(&p->p_itcallout, &p->p_mtx, PWAIT, "ritwait", 0);
255 KASSERT(!timevalisset(&p->p_realtimer.it_value),
256 ("realtime timer is still armed"));
257 }
258 PROC_UNLOCK(p);
259
260 /*
261 * Reset any sigio structures pointing to us as a result of
262 * F_SETOWN with our pid.
263 */
264 funsetownlst(&p->p_sigiolst);
265
266 /*
267 * If this process has an nlminfo data area (for lockd), release it
268 */
269 if (nlminfo_release_p != NULL && p->p_nlminfo != NULL)
270 (*nlminfo_release_p)(p);
271
272 /*
273 * Close open files and release open-file table.
274 * This may block!
275 */
276 fdfree(td);
277
278 /*
279 * If this thread tickled GEOM, we need to wait for the giggling to
280 * stop before we return to userland
281 */
282 if (td->td_pflags & TDP_GEOM)
283 g_waitidle();
284
285 /*
286 * Remove ourself from our leader's peer list and wake our leader.
287 */
288 mtx_lock(&ppeers_lock);
289 if (p->p_leader->p_peers) {
290 q = p->p_leader;
291 while (q->p_peers != p)
292 q = q->p_peers;
293 q->p_peers = p->p_peers;
294 wakeup(p->p_leader);
295 }
296 mtx_unlock(&ppeers_lock);
297
298 vmspace_exit(td);
299
300 sx_xlock(&proctree_lock);
301 if (SESS_LEADER(p)) {
302 struct session *sp;
303
304 sp = p->p_session;
305
306 SESS_LOCK(sp);
307 ttyvp = sp->s_ttyvp;
308 sp->s_ttyvp = NULL;
309 SESS_UNLOCK(sp);
310
311 if (ttyvp != NULL) {
312 /*
313 * Controlling process.
314 * Signal foreground pgrp and revoke access to
315 * controlling terminal.
316 *
317 * There is no need to drain the terminal here,
318 * because this will be done on revocation.
319 */
320 if (sp->s_ttyp != NULL) {
321 struct tty *tp = sp->s_ttyp;
322
323 tty_lock(tp);
324 tty_signal_pgrp(tp, SIGHUP);
325 tty_unlock(tp);
326
327 /*
328 * The tty could have been revoked
329 * if we blocked.
330 */
331 if (ttyvp->v_type != VBAD) {
332 sx_xunlock(&proctree_lock);
333 VOP_LOCK(ttyvp, LK_EXCLUSIVE);
334 VOP_REVOKE(ttyvp, REVOKEALL);
335 VOP_UNLOCK(ttyvp, 0);
336 sx_xlock(&proctree_lock);
337 }
338 }
339 /*
340 * s_ttyp is not zero'd; we use this to indicate that
341 * the session once had a controlling terminal.
342 * (for logging and informational purposes)
343 */
344 }
345 SESS_LOCK(p->p_session);
346 sp->s_leader = NULL;
347 SESS_UNLOCK(p->p_session);
348 }
349 fixjobc(p, p->p_pgrp, 0);
350 sx_xunlock(&proctree_lock);
351 (void)acct_process(td);
352
353 /* Release the TTY now we've unlocked everything. */
354 if (ttyvp != NULL)
355 vrele(ttyvp);
356 #ifdef KTRACE
357 /*
358 * Disable tracing, then drain any pending records and release
359 * the trace file.
360 */
361 if (p->p_traceflag != 0) {
362 PROC_LOCK(p);
363 mtx_lock(&ktrace_mtx);
364 p->p_traceflag = 0;
365 mtx_unlock(&ktrace_mtx);
366 PROC_UNLOCK(p);
367 ktrprocexit(td);
368 PROC_LOCK(p);
369 mtx_lock(&ktrace_mtx);
370 tracevp = p->p_tracevp;
371 p->p_tracevp = NULL;
372 tracecred = p->p_tracecred;
373 p->p_tracecred = NULL;
374 mtx_unlock(&ktrace_mtx);
375 PROC_UNLOCK(p);
376 if (tracevp != NULL) {
377 locked = VFS_LOCK_GIANT(tracevp->v_mount);
378 vrele(tracevp);
379 VFS_UNLOCK_GIANT(locked);
380 }
381 if (tracecred != NULL)
382 crfree(tracecred);
383 }
384 #endif
385 /*
386 * Release reference to text vnode
387 */
388 if ((vtmp = p->p_textvp) != NULL) {
389 p->p_textvp = NULL;
390 locked = VFS_LOCK_GIANT(vtmp->v_mount);
391 vrele(vtmp);
392 VFS_UNLOCK_GIANT(locked);
393 }
394
395 /*
396 * Release our limits structure.
397 */
398 PROC_LOCK(p);
399 plim = p->p_limit;
400 p->p_limit = NULL;
401 PROC_UNLOCK(p);
402 lim_free(plim);
403
404 /*
405 * Remove proc from allproc queue and pidhash chain.
406 * Place onto zombproc. Unlink from parent's child list.
407 */
408 sx_xlock(&allproc_lock);
409 LIST_REMOVE(p, p_list);
410 LIST_INSERT_HEAD(&zombproc, p, p_list);
411 LIST_REMOVE(p, p_hash);
412 sx_xunlock(&allproc_lock);
413
414 /*
415 * Call machine-dependent code to release any
416 * machine-dependent resources other than the address space.
417 * The address space is released by "vmspace_exitfree(p)" in
418 * vm_waitproc().
419 */
420 cpu_exit(td);
421
422 WITNESS_WARN(WARN_PANIC, NULL, "process (pid %d) exiting", p->p_pid);
423
424 /*
425 * Reparent all of our children to init.
426 */
427 sx_xlock(&proctree_lock);
428 q = LIST_FIRST(&p->p_children);
429 if (q != NULL) /* only need this if any child is S_ZOMB */
430 wakeup(initproc);
431 for (; q != NULL; q = nq) {
432 nq = LIST_NEXT(q, p_sibling);
433 PROC_LOCK(q);
434 proc_reparent(q, initproc);
435 q->p_sigparent = SIGCHLD;
436 /*
437 * Traced processes are killed
438 * since their existence means someone is screwing up.
439 */
440 if (q->p_flag & P_TRACED) {
441 q->p_flag &= ~(P_TRACED | P_STOPPED_TRACE);
442 psignal(q, SIGKILL);
443 }
444 PROC_UNLOCK(q);
445 }
446
447 /* Save exit status. */
448 PROC_LOCK(p);
449 p->p_xstat = rv;
450 p->p_xthread = td;
451
452 #ifdef KDTRACE_HOOKS
453 /*
454 * Tell the DTrace fasttrap provider about the exit if it
455 * has declared an interest.
456 */
457 if (dtrace_fasttrap_exit)
458 dtrace_fasttrap_exit(p);
459 #endif
460
461 /*
462 * Notify interested parties of our demise.
463 */
464 KNOTE_LOCKED(&p->p_klist, NOTE_EXIT);
465
466 #ifdef KDTRACE_HOOKS
467 int reason = CLD_EXITED;
468 if (WCOREDUMP(rv))
469 reason = CLD_DUMPED;
470 else if (WIFSIGNALED(rv))
471 reason = CLD_KILLED;
472 SDT_PROBE(proc, kernel, , exit, reason, 0, 0, 0, 0);
473 #endif
474
475 /*
476 * Just delete all entries in the p_klist. At this point we won't
477 * report any more events, and there are nasty race conditions that
478 * can beat us if we don't.
479 */
480 knlist_clear(&p->p_klist, 1);
481
482 /*
483 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT
484 * flag set, or if the handler is set to SIG_IGN, notify process
485 * 1 instead (and hope it will handle this situation).
486 */
487 PROC_LOCK(p->p_pptr);
488 mtx_lock(&p->p_pptr->p_sigacts->ps_mtx);
489 if (p->p_pptr->p_sigacts->ps_flag & (PS_NOCLDWAIT | PS_CLDSIGIGN)) {
490 struct proc *pp;
491
492 mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
493 pp = p->p_pptr;
494 PROC_UNLOCK(pp);
495 proc_reparent(p, initproc);
496 p->p_sigparent = SIGCHLD;
497 PROC_LOCK(p->p_pptr);
498 /*
499 * If this was the last child of our parent, notify
500 * parent, so in case he was wait(2)ing, he will
501 * continue.
502 */
503 if (LIST_EMPTY(&pp->p_children))
504 wakeup(pp);
505 } else
506 mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
507
508 if (p->p_pptr == initproc)
509 psignal(p->p_pptr, SIGCHLD);
510 else if (p->p_sigparent != 0) {
511 if (p->p_sigparent == SIGCHLD)
512 childproc_exited(p);
513 else /* LINUX thread */
514 psignal(p->p_pptr, p->p_sigparent);
515 }
516 sx_xunlock(&proctree_lock);
517
518 /*
519 * The state PRS_ZOMBIE prevents other proesses from sending
520 * signal to the process, to avoid memory leak, we free memory
521 * for signal queue at the time when the state is set.
522 */
523 sigqueue_flush(&p->p_sigqueue);
524 sigqueue_flush(&td->td_sigqueue);
525
526 /*
527 * We have to wait until after acquiring all locks before
528 * changing p_state. We need to avoid all possible context
529 * switches (including ones from blocking on a mutex) while
530 * marked as a zombie. We also have to set the zombie state
531 * before we release the parent process' proc lock to avoid
532 * a lost wakeup. So, we first call wakeup, then we grab the
533 * sched lock, update the state, and release the parent process'
534 * proc lock.
535 */
536 wakeup(p->p_pptr);
537 sched_exit(p->p_pptr, td);
538 PROC_SLOCK(p);
539 p->p_state = PRS_ZOMBIE;
540 PROC_UNLOCK(p->p_pptr);
541
542 /*
543 * Hopefully no one will try to deliver a signal to the process this
544 * late in the game.
545 */
546 knlist_destroy(&p->p_klist);
547
548 /*
549 * Save our children's rusage information in our exit rusage.
550 */
551 ruadd(&p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux);
552
553 /*
554 * Make sure the scheduler takes this thread out of its tables etc.
555 * This will also release this thread's reference to the ucred.
556 * Other thread parts to release include pcb bits and such.
557 */
558 thread_exit();
559 }
560
561
562 #ifndef _SYS_SYSPROTO_H_
563 struct abort2_args {
564 char *why;
565 int nargs;
566 void **args;
567 };
568 #endif
569
570 int
571 abort2(struct thread *td, struct abort2_args *uap)
572 {
573 struct proc *p = td->td_proc;
574 struct sbuf *sb;
575 void *uargs[16];
576 int error, i, sig;
577
578 error = 0; /* satisfy compiler */
579
580 /*
581 * Do it right now so we can log either proper call of abort2(), or
582 * note, that invalid argument was passed. 512 is big enough to
583 * handle 16 arguments' descriptions with additional comments.
584 */
585 sb = sbuf_new(NULL, NULL, 512, SBUF_FIXEDLEN);
586 sbuf_clear(sb);
587 sbuf_printf(sb, "%s(pid %d uid %d) aborted: ",
588 p->p_comm, p->p_pid, td->td_ucred->cr_uid);
589 /*
590 * Since we can't return from abort2(), send SIGKILL in cases, where
591 * abort2() was called improperly
592 */
593 sig = SIGKILL;
594 /* Prevent from DoSes from user-space. */
595 if (uap->nargs < 0 || uap->nargs > 16)
596 goto out;
597 if (uap->nargs > 0) {
598 if (uap->args == NULL)
599 goto out;
600 error = copyin(uap->args, uargs, uap->nargs * sizeof(void *));
601 if (error != 0)
602 goto out;
603 }
604 /*
605 * Limit size of 'reason' string to 128. Will fit even when
606 * maximal number of arguments was chosen to be logged.
607 */
608 if (uap->why != NULL) {
609 error = sbuf_copyin(sb, uap->why, 128);
610 if (error < 0)
611 goto out;
612 } else {
613 sbuf_printf(sb, "(null)");
614 }
615 if (uap->nargs > 0) {
616 sbuf_printf(sb, "(");
617 for (i = 0;i < uap->nargs; i++)
618 sbuf_printf(sb, "%s%p", i == 0 ? "" : ", ", uargs[i]);
619 sbuf_printf(sb, ")");
620 }
621 /*
622 * Final stage: arguments were proper, string has been
623 * successfully copied from userspace, and copying pointers
624 * from user-space succeed.
625 */
626 sig = SIGABRT;
627 out:
628 if (sig == SIGKILL) {
629 sbuf_trim(sb);
630 sbuf_printf(sb, " (Reason text inaccessible)");
631 }
632 sbuf_cat(sb, "\n");
633 sbuf_finish(sb);
634 log(LOG_INFO, "%s", sbuf_data(sb));
635 sbuf_delete(sb);
636 exit1(td, W_EXITCODE(0, sig));
637 return (0);
638 }
639
640
641 #ifdef COMPAT_43
642 /*
643 * The dirty work is handled by kern_wait().
644 */
645 int
646 owait(struct thread *td, struct owait_args *uap __unused)
647 {
648 int error, status;
649
650 error = kern_wait(td, WAIT_ANY, &status, 0, NULL);
651 if (error == 0)
652 td->td_retval[1] = status;
653 return (error);
654 }
655 #endif /* COMPAT_43 */
656
657 /*
658 * The dirty work is handled by kern_wait().
659 */
660 int
661 wait4(struct thread *td, struct wait_args *uap)
662 {
663 struct rusage ru, *rup;
664 int error, status;
665
666 if (uap->rusage != NULL)
667 rup = &ru;
668 else
669 rup = NULL;
670 error = kern_wait(td, uap->pid, &status, uap->options, rup);
671 if (uap->status != NULL && error == 0)
672 error = copyout(&status, uap->status, sizeof(status));
673 if (uap->rusage != NULL && error == 0)
674 error = copyout(&ru, uap->rusage, sizeof(struct rusage));
675 return (error);
676 }
677
678 int
679 kern_wait(struct thread *td, pid_t pid, int *status, int options,
680 struct rusage *rusage)
681 {
682 struct proc *p, *q, *t;
683 int error, nfound;
684
685 AUDIT_ARG(pid, pid);
686
687 q = td->td_proc;
688 if (pid == 0) {
689 PROC_LOCK(q);
690 pid = -q->p_pgid;
691 PROC_UNLOCK(q);
692 }
693 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WLINUXCLONE))
694 return (EINVAL);
695 loop:
696 if (q->p_flag & P_STATCHILD) {
697 PROC_LOCK(q);
698 q->p_flag &= ~P_STATCHILD;
699 PROC_UNLOCK(q);
700 }
701 nfound = 0;
702 sx_xlock(&proctree_lock);
703 LIST_FOREACH(p, &q->p_children, p_sibling) {
704 PROC_LOCK(p);
705 if (pid != WAIT_ANY &&
706 p->p_pid != pid && p->p_pgid != -pid) {
707 PROC_UNLOCK(p);
708 continue;
709 }
710 if (p_canwait(td, p)) {
711 PROC_UNLOCK(p);
712 continue;
713 }
714
715 /*
716 * This special case handles a kthread spawned by linux_clone
717 * (see linux_misc.c). The linux_wait4 and linux_waitpid
718 * functions need to be able to distinguish between waiting
719 * on a process and waiting on a thread. It is a thread if
720 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
721 * signifies we want to wait for threads and not processes.
722 */
723 if ((p->p_sigparent != SIGCHLD) ^
724 ((options & WLINUXCLONE) != 0)) {
725 PROC_UNLOCK(p);
726 continue;
727 }
728
729 nfound++;
730 PROC_SLOCK(p);
731 if (p->p_state == PRS_ZOMBIE) {
732 if (rusage) {
733 *rusage = p->p_ru;
734 calcru(p, &rusage->ru_utime, &rusage->ru_stime);
735 }
736 PROC_SUNLOCK(p);
737 td->td_retval[0] = p->p_pid;
738 if (status)
739 *status = p->p_xstat; /* convert to int */
740 PROC_LOCK(q);
741 sigqueue_take(p->p_ksi);
742 PROC_UNLOCK(q);
743
744 /*
745 * If we got the child via a ptrace 'attach',
746 * we need to give it back to the old parent.
747 */
748 PROC_UNLOCK(p);
749 if (p->p_oppid && (t = pfind(p->p_oppid)) != NULL) {
750 PROC_LOCK(p);
751 p->p_oppid = 0;
752 proc_reparent(p, t);
753 PROC_UNLOCK(p);
754 tdsignal(t, NULL, SIGCHLD, p->p_ksi);
755 wakeup(t);
756 PROC_UNLOCK(t);
757 sx_xunlock(&proctree_lock);
758 return (0);
759 }
760
761 /*
762 * Remove other references to this process to ensure
763 * we have an exclusive reference.
764 */
765 sx_xlock(&allproc_lock);
766 LIST_REMOVE(p, p_list); /* off zombproc */
767 sx_xunlock(&allproc_lock);
768 LIST_REMOVE(p, p_sibling);
769 leavepgrp(p);
770 sx_xunlock(&proctree_lock);
771
772 /*
773 * As a side effect of this lock, we know that
774 * all other writes to this proc are visible now, so
775 * no more locking is needed for p.
776 */
777 PROC_LOCK(p);
778 p->p_xstat = 0; /* XXX: why? */
779 PROC_UNLOCK(p);
780 PROC_LOCK(q);
781 ruadd(&q->p_stats->p_cru, &q->p_crux, &p->p_ru,
782 &p->p_rux);
783 PROC_UNLOCK(q);
784
785 /*
786 * Decrement the count of procs running with this uid.
787 */
788 (void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
789
790 /*
791 * Free credentials, arguments, and sigacts.
792 */
793 crfree(p->p_ucred);
794 p->p_ucred = NULL;
795 pargs_drop(p->p_args);
796 p->p_args = NULL;
797 sigacts_free(p->p_sigacts);
798 p->p_sigacts = NULL;
799
800 /*
801 * Do any thread-system specific cleanups.
802 */
803 thread_wait(p);
804
805 /*
806 * Give vm and machine-dependent layer a chance
807 * to free anything that cpu_exit couldn't
808 * release while still running in process context.
809 */
810 vm_waitproc(p);
811 #ifdef MAC
812 mac_proc_destroy(p);
813 #endif
814 KASSERT(FIRST_THREAD_IN_PROC(p),
815 ("kern_wait: no residual thread!"));
816 uma_zfree(proc_zone, p);
817 sx_xlock(&allproc_lock);
818 nprocs--;
819 sx_xunlock(&allproc_lock);
820 return (0);
821 }
822 if ((p->p_flag & P_STOPPED_SIG) &&
823 (p->p_suspcount == p->p_numthreads) &&
824 (p->p_flag & P_WAITED) == 0 &&
825 (p->p_flag & P_TRACED || options & WUNTRACED)) {
826 PROC_SUNLOCK(p);
827 p->p_flag |= P_WAITED;
828 sx_xunlock(&proctree_lock);
829 td->td_retval[0] = p->p_pid;
830 if (status)
831 *status = W_STOPCODE(p->p_xstat);
832
833 PROC_LOCK(q);
834 sigqueue_take(p->p_ksi);
835 PROC_UNLOCK(q);
836 PROC_UNLOCK(p);
837
838 return (0);
839 }
840 PROC_SUNLOCK(p);
841 if (options & WCONTINUED && (p->p_flag & P_CONTINUED)) {
842 sx_xunlock(&proctree_lock);
843 td->td_retval[0] = p->p_pid;
844 p->p_flag &= ~P_CONTINUED;
845
846 PROC_LOCK(q);
847 sigqueue_take(p->p_ksi);
848 PROC_UNLOCK(q);
849 PROC_UNLOCK(p);
850
851 if (status)
852 *status = SIGCONT;
853 return (0);
854 }
855 PROC_UNLOCK(p);
856 }
857 if (nfound == 0) {
858 sx_xunlock(&proctree_lock);
859 return (ECHILD);
860 }
861 if (options & WNOHANG) {
862 sx_xunlock(&proctree_lock);
863 td->td_retval[0] = 0;
864 return (0);
865 }
866 PROC_LOCK(q);
867 sx_xunlock(&proctree_lock);
868 if (q->p_flag & P_STATCHILD) {
869 q->p_flag &= ~P_STATCHILD;
870 error = 0;
871 } else
872 error = msleep(q, &q->p_mtx, PWAIT | PCATCH, "wait", 0);
873 PROC_UNLOCK(q);
874 if (error)
875 return (error);
876 goto loop;
877 }
878
879 /*
880 * Make process 'parent' the new parent of process 'child'.
881 * Must be called with an exclusive hold of proctree lock.
882 */
883 void
884 proc_reparent(struct proc *child, struct proc *parent)
885 {
886
887 sx_assert(&proctree_lock, SX_XLOCKED);
888 PROC_LOCK_ASSERT(child, MA_OWNED);
889 if (child->p_pptr == parent)
890 return;
891
892 PROC_LOCK(child->p_pptr);
893 sigqueue_take(child->p_ksi);
894 PROC_UNLOCK(child->p_pptr);
895 LIST_REMOVE(child, p_sibling);
896 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
897 child->p_pptr = parent;
898 }
899
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