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: releng/8.4/sys/kern/kern_exit.c 247350 2013-02-26 21:05:06Z jhb $");
39
40 #include "opt_compat.h"
41 #include "opt_kdtrace.h"
42 #include "opt_ktrace.h"
43
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/sysproto.h>
47 #include <sys/eventhandler.h>
48 #include <sys/kernel.h>
49 #include <sys/malloc.h>
50 #include <sys/lock.h>
51 #include <sys/mutex.h>
52 #include <sys/proc.h>
53 #include <sys/pioctl.h>
54 #include <sys/jail.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, exit);
94 SDT_PROBE_ARGTYPE(proc, kernel, , exit, 0, "int");
95
96 /* Hook for NFS teardown procedure. */
97 void (*nlminfo_release_p)(struct proc *p);
98
99 /*
100 * exit -- death of process.
101 */
102 void
103 sys_exit(struct thread *td, struct sys_exit_args *uap)
104 {
105
106 exit1(td, W_EXITCODE(uap->rval, 0));
107 /* NOTREACHED */
108 }
109
110 /*
111 * Exit: deallocate address space and other resources, change proc state to
112 * zombie, and unlink proc from allproc and parent's lists. Save exit status
113 * and rusage for wait(). Check for child processes and orphan them.
114 */
115 void
116 exit1(struct thread *td, int rv)
117 {
118 struct proc *p, *nq, *q;
119 struct vnode *vtmp;
120 struct vnode *ttyvp = NULL;
121 struct plimit *plim;
122 int locked;
123
124 mtx_assert(&Giant, MA_NOTOWNED);
125
126 p = td->td_proc;
127 /*
128 * XXX in case we're rebooting we just let init die in order to
129 * work around an unsolved stack overflow seen very late during
130 * shutdown on sparc64 when the gmirror worker process exists.
131 */
132 if (p == initproc && rebooting == 0) {
133 printf("init died (signal %d, exit %d)\n",
134 WTERMSIG(rv), WEXITSTATUS(rv));
135 panic("Going nowhere without my init!");
136 }
137
138 /*
139 * MUST abort all other threads before proceeding past here.
140 */
141 PROC_LOCK(p);
142 while (p->p_flag & P_HADTHREADS) {
143 /*
144 * First check if some other thread got here before us..
145 * if so, act apropriatly, (exit or suspend);
146 */
147 thread_suspend_check(0);
148
149 /*
150 * Kill off the other threads. This requires
151 * some co-operation from other parts of the kernel
152 * so it may not be instantaneous. With this state set
153 * any thread entering the kernel from userspace will
154 * thread_exit() in trap(). Any thread attempting to
155 * sleep will return immediately with EINTR or EWOULDBLOCK
156 * which will hopefully force them to back out to userland
157 * freeing resources as they go. Any thread attempting
158 * to return to userland will thread_exit() from userret().
159 * thread_exit() will unsuspend us when the last of the
160 * other threads exits.
161 * If there is already a thread singler after resumption,
162 * calling thread_single will fail; in that case, we just
163 * re-check all suspension request, the thread should
164 * either be suspended there or exit.
165 */
166 if (! thread_single(SINGLE_EXIT))
167 break;
168
169 /*
170 * All other activity in this process is now stopped.
171 * Threading support has been turned off.
172 */
173 }
174 KASSERT(p->p_numthreads == 1,
175 ("exit1: proc %p exiting with %d threads", p, p->p_numthreads));
176 /*
177 * Wakeup anyone in procfs' PIOCWAIT. They should have a hold
178 * on our vmspace, so we should block below until they have
179 * released their reference to us. Note that if they have
180 * requested S_EXIT stops we will block here until they ack
181 * via PIOCCONT.
182 */
183 _STOPEVENT(p, S_EXIT, rv);
184
185 /*
186 * Ignore any pending request to stop due to a stop signal.
187 * Once P_WEXIT is set, future requests will be ignored as
188 * well.
189 */
190 p->p_flag &= ~P_STOPPED_SIG;
191 KASSERT(!P_SHOULDSTOP(p), ("exiting process is stopped"));
192
193 /*
194 * Note that we are exiting and do another wakeup of anyone in
195 * PIOCWAIT in case they aren't listening for S_EXIT stops or
196 * decided to wait again after we told them we are exiting.
197 */
198 p->p_flag |= P_WEXIT;
199 wakeup(&p->p_stype);
200
201 /*
202 * Wait for any processes that have a hold on our vmspace to
203 * release their reference.
204 */
205 while (p->p_lock > 0)
206 msleep(&p->p_lock, &p->p_mtx, PWAIT, "exithold", 0);
207
208 p->p_xstat = rv; /* Let event handler change exit status */
209 PROC_UNLOCK(p);
210 /* Drain the limit callout while we don't have the proc locked */
211 callout_drain(&p->p_limco);
212
213 #ifdef AUDIT
214 /*
215 * The Sun BSM exit token contains two components: an exit status as
216 * passed to exit(), and a return value to indicate what sort of exit
217 * it was. The exit status is WEXITSTATUS(rv), but it's not clear
218 * what the return value is.
219 */
220 AUDIT_ARG_EXIT(WEXITSTATUS(rv), 0);
221 AUDIT_SYSCALL_EXIT(0, td);
222 #endif
223
224 /* Are we a task leader? */
225 if (p == p->p_leader) {
226 mtx_lock(&ppeers_lock);
227 q = p->p_peers;
228 while (q != NULL) {
229 PROC_LOCK(q);
230 psignal(q, SIGKILL);
231 PROC_UNLOCK(q);
232 q = q->p_peers;
233 }
234 while (p->p_peers != NULL)
235 msleep(p, &ppeers_lock, PWAIT, "exit1", 0);
236 mtx_unlock(&ppeers_lock);
237 }
238
239 /*
240 * Check if any loadable modules need anything done at process exit.
241 * E.g. SYSV IPC stuff
242 * XXX what if one of these generates an error?
243 */
244 EVENTHANDLER_INVOKE(process_exit, p);
245
246 /*
247 * If parent is waiting for us to exit or exec,
248 * P_PPWAIT is set; we will wakeup the parent below.
249 */
250 PROC_LOCK(p);
251 rv = p->p_xstat; /* Event handler could change exit status */
252 stopprofclock(p);
253 p->p_flag &= ~(P_TRACED | P_PPWAIT);
254
255 /*
256 * Stop the real interval timer. If the handler is currently
257 * executing, prevent it from rearming itself and let it finish.
258 */
259 if (timevalisset(&p->p_realtimer.it_value) &&
260 callout_stop(&p->p_itcallout) == 0) {
261 timevalclear(&p->p_realtimer.it_interval);
262 msleep(&p->p_itcallout, &p->p_mtx, PWAIT, "ritwait", 0);
263 KASSERT(!timevalisset(&p->p_realtimer.it_value),
264 ("realtime timer is still armed"));
265 }
266 PROC_UNLOCK(p);
267
268 /*
269 * Reset any sigio structures pointing to us as a result of
270 * F_SETOWN with our pid.
271 */
272 funsetownlst(&p->p_sigiolst);
273
274 /*
275 * If this process has an nlminfo data area (for lockd), release it
276 */
277 if (nlminfo_release_p != NULL && p->p_nlminfo != NULL)
278 (*nlminfo_release_p)(p);
279
280 /*
281 * Close open files and release open-file table.
282 * This may block!
283 */
284 fdfree(td);
285
286 /*
287 * If this thread tickled GEOM, we need to wait for the giggling to
288 * stop before we return to userland
289 */
290 if (td->td_pflags & TDP_GEOM)
291 g_waitidle();
292
293 /*
294 * Remove ourself from our leader's peer list and wake our leader.
295 */
296 mtx_lock(&ppeers_lock);
297 if (p->p_leader->p_peers) {
298 q = p->p_leader;
299 while (q->p_peers != p)
300 q = q->p_peers;
301 q->p_peers = p->p_peers;
302 wakeup(p->p_leader);
303 }
304 mtx_unlock(&ppeers_lock);
305
306 vmspace_exit(td);
307
308 sx_xlock(&proctree_lock);
309 if (SESS_LEADER(p)) {
310 struct session *sp = p->p_session;
311 struct tty *tp;
312
313 /*
314 * s_ttyp is not zero'd; we use this to indicate that
315 * the session once had a controlling terminal. (for
316 * logging and informational purposes)
317 */
318 SESS_LOCK(sp);
319 ttyvp = sp->s_ttyvp;
320 tp = sp->s_ttyp;
321 sp->s_ttyvp = NULL;
322 sp->s_leader = NULL;
323 SESS_UNLOCK(sp);
324
325 /*
326 * Signal foreground pgrp and revoke access to
327 * controlling terminal if it has not been revoked
328 * already.
329 *
330 * Because the TTY may have been revoked in the mean
331 * time and could already have a new session associated
332 * with it, make sure we don't send a SIGHUP to a
333 * foreground process group that does not belong to this
334 * session.
335 */
336
337 if (tp != NULL) {
338 tty_lock(tp);
339 if (tp->t_session == sp)
340 tty_signal_pgrp(tp, SIGHUP);
341 tty_unlock(tp);
342 }
343
344 if (ttyvp != NULL) {
345 sx_xunlock(&proctree_lock);
346 if (vn_lock(ttyvp, LK_EXCLUSIVE) == 0) {
347 VOP_REVOKE(ttyvp, REVOKEALL);
348 VOP_UNLOCK(ttyvp, 0);
349 }
350 sx_xlock(&proctree_lock);
351 }
352 }
353 fixjobc(p, p->p_pgrp, 0);
354 sx_xunlock(&proctree_lock);
355 (void)acct_process(td);
356
357 /* Release the TTY now we've unlocked everything. */
358 if (ttyvp != NULL)
359 vrele(ttyvp);
360 #ifdef KTRACE
361 ktrprocexit(td);
362 #endif
363 /*
364 * Release reference to text vnode
365 */
366 if ((vtmp = p->p_textvp) != NULL) {
367 p->p_textvp = NULL;
368 locked = VFS_LOCK_GIANT(vtmp->v_mount);
369 vrele(vtmp);
370 VFS_UNLOCK_GIANT(locked);
371 }
372
373 /*
374 * Release our limits structure.
375 */
376 PROC_LOCK(p);
377 plim = p->p_limit;
378 p->p_limit = NULL;
379 PROC_UNLOCK(p);
380 lim_free(plim);
381
382 /*
383 * Remove proc from allproc queue and pidhash chain.
384 * Place onto zombproc. Unlink from parent's child list.
385 */
386 sx_xlock(&allproc_lock);
387 LIST_REMOVE(p, p_list);
388 LIST_INSERT_HEAD(&zombproc, p, p_list);
389 LIST_REMOVE(p, p_hash);
390 sx_xunlock(&allproc_lock);
391
392 /*
393 * Call machine-dependent code to release any
394 * machine-dependent resources other than the address space.
395 * The address space is released by "vmspace_exitfree(p)" in
396 * vm_waitproc().
397 */
398 cpu_exit(td);
399
400 WITNESS_WARN(WARN_PANIC, NULL, "process (pid %d) exiting", p->p_pid);
401
402 /*
403 * Reparent all of our children to init.
404 */
405 sx_xlock(&proctree_lock);
406 q = LIST_FIRST(&p->p_children);
407 if (q != NULL) /* only need this if any child is S_ZOMB */
408 wakeup(initproc);
409 for (; q != NULL; q = nq) {
410 nq = LIST_NEXT(q, p_sibling);
411 PROC_LOCK(q);
412 proc_reparent(q, initproc);
413 q->p_sigparent = SIGCHLD;
414 /*
415 * Traced processes are killed
416 * since their existence means someone is screwing up.
417 */
418 if (q->p_flag & P_TRACED) {
419 struct thread *temp;
420
421 q->p_flag &= ~(P_TRACED | P_STOPPED_TRACE);
422 FOREACH_THREAD_IN_PROC(q, temp)
423 temp->td_dbgflags &= ~TDB_SUSPEND;
424 psignal(q, SIGKILL);
425 }
426 PROC_UNLOCK(q);
427 }
428
429 /* Save exit status. */
430 PROC_LOCK(p);
431 p->p_xthread = td;
432
433 /* Tell the prison that we are gone. */
434 prison_proc_free(p->p_ucred->cr_prison);
435
436 #ifdef KDTRACE_HOOKS
437 /*
438 * Tell the DTrace fasttrap provider about the exit if it
439 * has declared an interest.
440 */
441 if (dtrace_fasttrap_exit)
442 dtrace_fasttrap_exit(p);
443 #endif
444
445 /*
446 * Notify interested parties of our demise.
447 */
448 KNOTE_LOCKED(&p->p_klist, NOTE_EXIT);
449
450 #ifdef KDTRACE_HOOKS
451 int reason = CLD_EXITED;
452 if (WCOREDUMP(rv))
453 reason = CLD_DUMPED;
454 else if (WIFSIGNALED(rv))
455 reason = CLD_KILLED;
456 SDT_PROBE(proc, kernel, , exit, reason, 0, 0, 0, 0);
457 #endif
458
459 /*
460 * Just delete all entries in the p_klist. At this point we won't
461 * report any more events, and there are nasty race conditions that
462 * can beat us if we don't.
463 */
464 knlist_clear(&p->p_klist, 1);
465
466 /*
467 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT
468 * flag set, or if the handler is set to SIG_IGN, notify process
469 * 1 instead (and hope it will handle this situation).
470 */
471 PROC_LOCK(p->p_pptr);
472 mtx_lock(&p->p_pptr->p_sigacts->ps_mtx);
473 if (p->p_pptr->p_sigacts->ps_flag & (PS_NOCLDWAIT | PS_CLDSIGIGN)) {
474 struct proc *pp;
475
476 mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
477 pp = p->p_pptr;
478 PROC_UNLOCK(pp);
479 proc_reparent(p, initproc);
480 p->p_sigparent = SIGCHLD;
481 PROC_LOCK(p->p_pptr);
482
483 /*
484 * Notify parent, so in case he was wait(2)ing or
485 * executing waitpid(2) with our pid, he will
486 * continue.
487 */
488 wakeup(pp);
489 } else
490 mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
491
492 if (p->p_pptr == initproc)
493 psignal(p->p_pptr, SIGCHLD);
494 else if (p->p_sigparent != 0) {
495 if (p->p_sigparent == SIGCHLD)
496 childproc_exited(p);
497 else /* LINUX thread */
498 psignal(p->p_pptr, p->p_sigparent);
499 }
500 sx_xunlock(&proctree_lock);
501
502 /*
503 * The state PRS_ZOMBIE prevents other proesses from sending
504 * signal to the process, to avoid memory leak, we free memory
505 * for signal queue at the time when the state is set.
506 */
507 sigqueue_flush(&p->p_sigqueue);
508 sigqueue_flush(&td->td_sigqueue);
509
510 /*
511 * We have to wait until after acquiring all locks before
512 * changing p_state. We need to avoid all possible context
513 * switches (including ones from blocking on a mutex) while
514 * marked as a zombie. We also have to set the zombie state
515 * before we release the parent process' proc lock to avoid
516 * a lost wakeup. So, we first call wakeup, then we grab the
517 * sched lock, update the state, and release the parent process'
518 * proc lock.
519 */
520 wakeup(p->p_pptr);
521 cv_broadcast(&p->p_pwait);
522 sched_exit(p->p_pptr, td);
523 PROC_SLOCK(p);
524 p->p_state = PRS_ZOMBIE;
525 PROC_UNLOCK(p->p_pptr);
526
527 /*
528 * Hopefully no one will try to deliver a signal to the process this
529 * late in the game.
530 */
531 knlist_destroy(&p->p_klist);
532
533 /*
534 * Save our children's rusage information in our exit rusage.
535 */
536 ruadd(&p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux);
537
538 /*
539 * Make sure the scheduler takes this thread out of its tables etc.
540 * This will also release this thread's reference to the ucred.
541 * Other thread parts to release include pcb bits and such.
542 */
543 thread_exit();
544 }
545
546
547 #ifndef _SYS_SYSPROTO_H_
548 struct abort2_args {
549 char *why;
550 int nargs;
551 void **args;
552 };
553 #endif
554
555 int
556 abort2(struct thread *td, struct abort2_args *uap)
557 {
558 struct proc *p = td->td_proc;
559 struct sbuf *sb;
560 void *uargs[16];
561 int error, i, sig;
562
563 /*
564 * Do it right now so we can log either proper call of abort2(), or
565 * note, that invalid argument was passed. 512 is big enough to
566 * handle 16 arguments' descriptions with additional comments.
567 */
568 sb = sbuf_new(NULL, NULL, 512, SBUF_FIXEDLEN);
569 sbuf_clear(sb);
570 sbuf_printf(sb, "%s(pid %d uid %d) aborted: ",
571 p->p_comm, p->p_pid, td->td_ucred->cr_uid);
572 /*
573 * Since we can't return from abort2(), send SIGKILL in cases, where
574 * abort2() was called improperly
575 */
576 sig = SIGKILL;
577 /* Prevent from DoSes from user-space. */
578 if (uap->nargs < 0 || uap->nargs > 16)
579 goto out;
580 if (uap->nargs > 0) {
581 if (uap->args == NULL)
582 goto out;
583 error = copyin(uap->args, uargs, uap->nargs * sizeof(void *));
584 if (error != 0)
585 goto out;
586 }
587 /*
588 * Limit size of 'reason' string to 128. Will fit even when
589 * maximal number of arguments was chosen to be logged.
590 */
591 if (uap->why != NULL) {
592 error = sbuf_copyin(sb, uap->why, 128);
593 if (error < 0)
594 goto out;
595 } else {
596 sbuf_printf(sb, "(null)");
597 }
598 if (uap->nargs > 0) {
599 sbuf_printf(sb, "(");
600 for (i = 0;i < uap->nargs; i++)
601 sbuf_printf(sb, "%s%p", i == 0 ? "" : ", ", uargs[i]);
602 sbuf_printf(sb, ")");
603 }
604 /*
605 * Final stage: arguments were proper, string has been
606 * successfully copied from userspace, and copying pointers
607 * from user-space succeed.
608 */
609 sig = SIGABRT;
610 out:
611 if (sig == SIGKILL) {
612 sbuf_trim(sb);
613 sbuf_printf(sb, " (Reason text inaccessible)");
614 }
615 sbuf_cat(sb, "\n");
616 sbuf_finish(sb);
617 log(LOG_INFO, "%s", sbuf_data(sb));
618 sbuf_delete(sb);
619 exit1(td, W_EXITCODE(0, sig));
620 return (0);
621 }
622
623
624 #ifdef COMPAT_43
625 /*
626 * The dirty work is handled by kern_wait().
627 */
628 int
629 owait(struct thread *td, struct owait_args *uap __unused)
630 {
631 int error, status;
632
633 error = kern_wait(td, WAIT_ANY, &status, 0, NULL);
634 if (error == 0)
635 td->td_retval[1] = status;
636 return (error);
637 }
638 #endif /* COMPAT_43 */
639
640 /*
641 * The dirty work is handled by kern_wait().
642 */
643 int
644 wait4(struct thread *td, struct wait_args *uap)
645 {
646 struct rusage ru, *rup;
647 int error, status;
648
649 if (uap->rusage != NULL)
650 rup = &ru;
651 else
652 rup = NULL;
653 error = kern_wait(td, uap->pid, &status, uap->options, rup);
654 if (uap->status != NULL && error == 0)
655 error = copyout(&status, uap->status, sizeof(status));
656 if (uap->rusage != NULL && error == 0)
657 error = copyout(&ru, uap->rusage, sizeof(struct rusage));
658 return (error);
659 }
660
661 /*
662 * Reap the remains of a zombie process and optionally return status and
663 * rusage. Asserts and will release both the proctree_lock and the process
664 * lock as part of its work.
665 */
666 static void
667 proc_reap(struct thread *td, struct proc *p, int *status, int options,
668 struct rusage *rusage)
669 {
670 struct proc *q, *t;
671
672 sx_assert(&proctree_lock, SA_XLOCKED);
673 PROC_LOCK_ASSERT(p, MA_OWNED);
674 PROC_SLOCK_ASSERT(p, MA_OWNED);
675 KASSERT(p->p_state == PRS_ZOMBIE, ("proc_reap: !PRS_ZOMBIE"));
676
677 q = td->td_proc;
678 if (rusage) {
679 *rusage = p->p_ru;
680 calcru(p, &rusage->ru_utime, &rusage->ru_stime);
681 }
682 PROC_SUNLOCK(p);
683 td->td_retval[0] = p->p_pid;
684 if (status)
685 *status = p->p_xstat; /* convert to int */
686 if (options & WNOWAIT) {
687 /*
688 * Only poll, returning the status. Caller does not wish to
689 * release the proc struct just yet.
690 */
691 PROC_UNLOCK(p);
692 sx_xunlock(&proctree_lock);
693 return;
694 }
695
696 PROC_LOCK(q);
697 sigqueue_take(p->p_ksi);
698 PROC_UNLOCK(q);
699 PROC_UNLOCK(p);
700
701 /*
702 * If we got the child via a ptrace 'attach', we need to give it back
703 * to the old parent.
704 */
705 if (p->p_oppid && (t = pfind(p->p_oppid)) != NULL) {
706 PROC_LOCK(p);
707 p->p_oppid = 0;
708 proc_reparent(p, t);
709 PROC_UNLOCK(p);
710 tdsignal(t, NULL, SIGCHLD, p->p_ksi);
711 wakeup(t);
712 cv_broadcast(&p->p_pwait);
713 PROC_UNLOCK(t);
714 sx_xunlock(&proctree_lock);
715 return;
716 }
717
718 /*
719 * Remove other references to this process to ensure we have an
720 * exclusive reference.
721 */
722 sx_xlock(&allproc_lock);
723 LIST_REMOVE(p, p_list); /* off zombproc */
724 sx_xunlock(&allproc_lock);
725 LIST_REMOVE(p, p_sibling);
726 leavepgrp(p);
727 sx_xunlock(&proctree_lock);
728
729 /*
730 * As a side effect of this lock, we know that all other writes to
731 * this proc are visible now, so no more locking is needed for p.
732 */
733 PROC_LOCK(p);
734 p->p_xstat = 0; /* XXX: why? */
735 PROC_UNLOCK(p);
736 PROC_LOCK(q);
737 ruadd(&q->p_stats->p_cru, &q->p_crux, &p->p_ru, &p->p_rux);
738 PROC_UNLOCK(q);
739
740 /*
741 * Decrement the count of procs running with this uid.
742 */
743 (void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
744
745 /*
746 * Free credentials, arguments, and sigacts.
747 */
748 crfree(p->p_ucred);
749 p->p_ucred = NULL;
750 pargs_drop(p->p_args);
751 p->p_args = NULL;
752 sigacts_free(p->p_sigacts);
753 p->p_sigacts = NULL;
754
755 /*
756 * Do any thread-system specific cleanups.
757 */
758 thread_wait(p);
759
760 /*
761 * Give vm and machine-dependent layer a chance to free anything that
762 * cpu_exit couldn't release while still running in process context.
763 */
764 vm_waitproc(p);
765 #ifdef MAC
766 mac_proc_destroy(p);
767 #endif
768 KASSERT(FIRST_THREAD_IN_PROC(p),
769 ("proc_reap: no residual thread!"));
770 uma_zfree(proc_zone, p);
771 sx_xlock(&allproc_lock);
772 nprocs--;
773 sx_xunlock(&allproc_lock);
774 }
775
776 int
777 kern_wait(struct thread *td, pid_t pid, int *status, int options,
778 struct rusage *rusage)
779 {
780 struct proc *p, *q;
781 int error, nfound;
782
783 AUDIT_ARG_PID(pid);
784 AUDIT_ARG_VALUE(options);
785
786 q = td->td_proc;
787 if (pid == 0) {
788 PROC_LOCK(q);
789 pid = -q->p_pgid;
790 PROC_UNLOCK(q);
791 }
792 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WNOWAIT|WLINUXCLONE))
793 return (EINVAL);
794 loop:
795 if (q->p_flag & P_STATCHILD) {
796 PROC_LOCK(q);
797 q->p_flag &= ~P_STATCHILD;
798 PROC_UNLOCK(q);
799 }
800 nfound = 0;
801 sx_xlock(&proctree_lock);
802 LIST_FOREACH(p, &q->p_children, p_sibling) {
803 PROC_LOCK(p);
804 if (pid != WAIT_ANY &&
805 p->p_pid != pid && p->p_pgid != -pid) {
806 PROC_UNLOCK(p);
807 continue;
808 }
809 if (p_canwait(td, p)) {
810 PROC_UNLOCK(p);
811 continue;
812 }
813
814 /*
815 * This special case handles a kthread spawned by linux_clone
816 * (see linux_misc.c). The linux_wait4 and linux_waitpid
817 * functions need to be able to distinguish between waiting
818 * on a process and waiting on a thread. It is a thread if
819 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
820 * signifies we want to wait for threads and not processes.
821 */
822 if ((p->p_sigparent != SIGCHLD) ^
823 ((options & WLINUXCLONE) != 0)) {
824 PROC_UNLOCK(p);
825 continue;
826 }
827
828 nfound++;
829 PROC_SLOCK(p);
830 if (p->p_state == PRS_ZOMBIE) {
831 proc_reap(td, p, status, options, rusage);
832 return (0);
833 }
834 if ((p->p_flag & P_STOPPED_SIG) &&
835 (p->p_suspcount == p->p_numthreads) &&
836 (p->p_flag & P_WAITED) == 0 &&
837 (p->p_flag & P_TRACED || options & WUNTRACED)) {
838 PROC_SUNLOCK(p);
839 p->p_flag |= P_WAITED;
840 sx_xunlock(&proctree_lock);
841 td->td_retval[0] = p->p_pid;
842 if (status)
843 *status = W_STOPCODE(p->p_xstat);
844
845 PROC_LOCK(q);
846 sigqueue_take(p->p_ksi);
847 PROC_UNLOCK(q);
848 PROC_UNLOCK(p);
849
850 return (0);
851 }
852 PROC_SUNLOCK(p);
853 if (options & WCONTINUED && (p->p_flag & P_CONTINUED)) {
854 sx_xunlock(&proctree_lock);
855 td->td_retval[0] = p->p_pid;
856 p->p_flag &= ~P_CONTINUED;
857
858 PROC_LOCK(q);
859 sigqueue_take(p->p_ksi);
860 PROC_UNLOCK(q);
861 PROC_UNLOCK(p);
862
863 if (status)
864 *status = SIGCONT;
865 return (0);
866 }
867 PROC_UNLOCK(p);
868 }
869 if (nfound == 0) {
870 sx_xunlock(&proctree_lock);
871 return (ECHILD);
872 }
873 if (options & WNOHANG) {
874 sx_xunlock(&proctree_lock);
875 td->td_retval[0] = 0;
876 return (0);
877 }
878 PROC_LOCK(q);
879 sx_xunlock(&proctree_lock);
880 if (q->p_flag & P_STATCHILD) {
881 q->p_flag &= ~P_STATCHILD;
882 error = 0;
883 } else
884 error = msleep(q, &q->p_mtx, PWAIT | PCATCH, "wait", 0);
885 PROC_UNLOCK(q);
886 if (error)
887 return (error);
888 goto loop;
889 }
890
891 /*
892 * Make process 'parent' the new parent of process 'child'.
893 * Must be called with an exclusive hold of proctree lock.
894 */
895 void
896 proc_reparent(struct proc *child, struct proc *parent)
897 {
898
899 sx_assert(&proctree_lock, SX_XLOCKED);
900 PROC_LOCK_ASSERT(child, MA_OWNED);
901 if (child->p_pptr == parent)
902 return;
903
904 PROC_LOCK(child->p_pptr);
905 sigqueue_take(child->p_ksi);
906 PROC_UNLOCK(child->p_pptr);
907 LIST_REMOVE(child, p_sibling);
908 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
909 child->p_pptr = parent;
910 }
Cache object: c7b6d5e9cbc3aba75429dcceaaf73c71
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