The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_exit.c

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    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/10.3/sys/kern/kern_exit.c 293473 2016-01-09 14:08:10Z dchagin $");
   39 
   40 #include "opt_compat.h"
   41 #include "opt_kdtrace.h"
   42 #include "opt_ktrace.h"
   43 #include "opt_procdesc.h"
   44 
   45 #include <sys/param.h>
   46 #include <sys/systm.h>
   47 #include <sys/sysproto.h>
   48 #include <sys/capsicum.h>
   49 #include <sys/eventhandler.h>
   50 #include <sys/kernel.h>
   51 #include <sys/malloc.h>
   52 #include <sys/lock.h>
   53 #include <sys/mutex.h>
   54 #include <sys/proc.h>
   55 #include <sys/procdesc.h>
   56 #include <sys/pioctl.h>
   57 #include <sys/jail.h>
   58 #include <sys/tty.h>
   59 #include <sys/wait.h>
   60 #include <sys/vmmeter.h>
   61 #include <sys/vnode.h>
   62 #include <sys/racct.h>
   63 #include <sys/resourcevar.h>
   64 #include <sys/sbuf.h>
   65 #include <sys/signalvar.h>
   66 #include <sys/sched.h>
   67 #include <sys/sx.h>
   68 #include <sys/syscallsubr.h>
   69 #include <sys/syslog.h>
   70 #include <sys/ptrace.h>
   71 #include <sys/acct.h>           /* for acct_process() function prototype */
   72 #include <sys/filedesc.h>
   73 #include <sys/sdt.h>
   74 #include <sys/shm.h>
   75 #include <sys/sem.h>
   76 #include <sys/umtx.h>
   77 #ifdef KTRACE
   78 #include <sys/ktrace.h>
   79 #endif
   80 
   81 #include <security/audit/audit.h>
   82 #include <security/mac/mac_framework.h>
   83 
   84 #include <vm/vm.h>
   85 #include <vm/vm_extern.h>
   86 #include <vm/vm_param.h>
   87 #include <vm/pmap.h>
   88 #include <vm/vm_map.h>
   89 #include <vm/vm_page.h>
   90 #include <vm/uma.h>
   91 
   92 #ifdef KDTRACE_HOOKS
   93 #include <sys/dtrace_bsd.h>
   94 dtrace_execexit_func_t  dtrace_fasttrap_exit;
   95 #endif
   96 
   97 SDT_PROVIDER_DECLARE(proc);
   98 SDT_PROBE_DEFINE1(proc, kernel, , exit, "int");
   99 
  100 /* Hook for NFS teardown procedure. */
  101 void (*nlminfo_release_p)(struct proc *p);
  102 
  103 struct proc *
  104 proc_realparent(struct proc *child)
  105 {
  106         struct proc *p, *parent;
  107 
  108         sx_assert(&proctree_lock, SX_LOCKED);
  109         if ((child->p_treeflag & P_TREE_ORPHANED) == 0) {
  110                 if (child->p_oppid == 0 ||
  111                     child->p_pptr->p_pid == child->p_oppid)
  112                         parent = child->p_pptr;
  113                 else
  114                         parent = initproc;
  115                 return (parent);
  116         }
  117         for (p = child; (p->p_treeflag & P_TREE_FIRST_ORPHAN) == 0;) {
  118                 /* Cannot use LIST_PREV(), since the list head is not known. */
  119                 p = __containerof(p->p_orphan.le_prev, struct proc,
  120                     p_orphan.le_next);
  121                 KASSERT((p->p_treeflag & P_TREE_ORPHANED) != 0,
  122                     ("missing P_ORPHAN %p", p));
  123         }
  124         parent = __containerof(p->p_orphan.le_prev, struct proc,
  125             p_orphans.lh_first);
  126         return (parent);
  127 }
  128 
  129 void
  130 reaper_abandon_children(struct proc *p, bool exiting)
  131 {
  132         struct proc *p1, *p2, *ptmp;
  133 
  134         sx_assert(&proctree_lock, SX_LOCKED);
  135         KASSERT(p != initproc, ("reaper_abandon_children for initproc"));
  136         if ((p->p_treeflag & P_TREE_REAPER) == 0)
  137                 return;
  138         p1 = p->p_reaper;
  139         LIST_FOREACH_SAFE(p2, &p->p_reaplist, p_reapsibling, ptmp) {
  140                 LIST_REMOVE(p2, p_reapsibling);
  141                 p2->p_reaper = p1;
  142                 p2->p_reapsubtree = p->p_reapsubtree;
  143                 LIST_INSERT_HEAD(&p1->p_reaplist, p2, p_reapsibling);
  144                 if (exiting && p2->p_pptr == p) {
  145                         PROC_LOCK(p2);
  146                         proc_reparent(p2, p1);
  147                         PROC_UNLOCK(p2);
  148                 }
  149         }
  150         KASSERT(LIST_EMPTY(&p->p_reaplist), ("p_reaplist not empty"));
  151         p->p_treeflag &= ~P_TREE_REAPER;
  152 }
  153 
  154 static void
  155 clear_orphan(struct proc *p)
  156 {
  157         struct proc *p1;
  158 
  159         sx_assert(&proctree_lock, SA_XLOCKED);
  160         if ((p->p_treeflag & P_TREE_ORPHANED) == 0)
  161                 return;
  162         if ((p->p_treeflag & P_TREE_FIRST_ORPHAN) != 0) {
  163                 p1 = LIST_NEXT(p, p_orphan);
  164                 if (p1 != NULL)
  165                         p1->p_treeflag |= P_TREE_FIRST_ORPHAN;
  166                 p->p_treeflag &= ~P_TREE_FIRST_ORPHAN;
  167         }
  168         LIST_REMOVE(p, p_orphan);
  169         p->p_treeflag &= ~P_TREE_ORPHANED;
  170 }
  171 
  172 /*
  173  * exit -- death of process.
  174  */
  175 void
  176 sys_sys_exit(struct thread *td, struct sys_exit_args *uap)
  177 {
  178 
  179         exit1(td, W_EXITCODE(uap->rval, 0));
  180         /* NOTREACHED */
  181 }
  182 
  183 /*
  184  * Exit: deallocate address space and other resources, change proc state to
  185  * zombie, and unlink proc from allproc and parent's lists.  Save exit status
  186  * and rusage for wait().  Check for child processes and orphan them.
  187  */
  188 void
  189 exit1(struct thread *td, int rv)
  190 {
  191         struct proc *p, *nq, *q, *t;
  192         struct thread *tdt;
  193         struct vnode *ttyvp = NULL;
  194 
  195         mtx_assert(&Giant, MA_NOTOWNED);
  196 
  197         p = td->td_proc;
  198         /*
  199          * XXX in case we're rebooting we just let init die in order to
  200          * work around an unsolved stack overflow seen very late during
  201          * shutdown on sparc64 when the gmirror worker process exists.
  202          */
  203         if (p == initproc && rebooting == 0) {
  204                 printf("init died (signal %d, exit %d)\n",
  205                     WTERMSIG(rv), WEXITSTATUS(rv));
  206                 panic("Going nowhere without my init!");
  207         }
  208 
  209         /*
  210          * Deref SU mp, since the thread does not return to userspace.
  211          */
  212         if (softdep_ast_cleanup != NULL)
  213                 softdep_ast_cleanup();
  214 
  215         /*
  216          * MUST abort all other threads before proceeding past here.
  217          */
  218         PROC_LOCK(p);
  219         /*
  220          * First check if some other thread or external request got
  221          * here before us.  If so, act appropriately: exit or suspend.
  222          * We must ensure that stop requests are handled before we set
  223          * P_WEXIT.
  224          */
  225         thread_suspend_check(0);
  226         while (p->p_flag & P_HADTHREADS) {
  227                 /*
  228                  * Kill off the other threads. This requires
  229                  * some co-operation from other parts of the kernel
  230                  * so it may not be instantaneous.  With this state set
  231                  * any thread entering the kernel from userspace will
  232                  * thread_exit() in trap().  Any thread attempting to
  233                  * sleep will return immediately with EINTR or EWOULDBLOCK
  234                  * which will hopefully force them to back out to userland
  235                  * freeing resources as they go.  Any thread attempting
  236                  * to return to userland will thread_exit() from userret().
  237                  * thread_exit() will unsuspend us when the last of the
  238                  * other threads exits.
  239                  * If there is already a thread singler after resumption,
  240                  * calling thread_single will fail; in that case, we just
  241                  * re-check all suspension request, the thread should
  242                  * either be suspended there or exit.
  243                  */
  244                 if (!thread_single(p, SINGLE_EXIT))
  245                         /*
  246                          * All other activity in this process is now
  247                          * stopped.  Threading support has been turned
  248                          * off.
  249                          */
  250                         break;
  251                 /*
  252                  * Recheck for new stop or suspend requests which
  253                  * might appear while process lock was dropped in
  254                  * thread_single().
  255                  */
  256                 thread_suspend_check(0);
  257         }
  258         KASSERT(p->p_numthreads == 1,
  259             ("exit1: proc %p exiting with %d threads", p, p->p_numthreads));
  260         racct_sub(p, RACCT_NTHR, 1);
  261         /*
  262          * Wakeup anyone in procfs' PIOCWAIT.  They should have a hold
  263          * on our vmspace, so we should block below until they have
  264          * released their reference to us.  Note that if they have
  265          * requested S_EXIT stops we will block here until they ack
  266          * via PIOCCONT.
  267          */
  268         _STOPEVENT(p, S_EXIT, rv);
  269 
  270         /*
  271          * Ignore any pending request to stop due to a stop signal.
  272          * Once P_WEXIT is set, future requests will be ignored as
  273          * well.
  274          */
  275         p->p_flag &= ~P_STOPPED_SIG;
  276         KASSERT(!P_SHOULDSTOP(p), ("exiting process is stopped"));
  277 
  278         /*
  279          * Note that we are exiting and do another wakeup of anyone in
  280          * PIOCWAIT in case they aren't listening for S_EXIT stops or
  281          * decided to wait again after we told them we are exiting.
  282          */
  283         p->p_flag |= P_WEXIT;
  284         wakeup(&p->p_stype);
  285 
  286         /*
  287          * Wait for any processes that have a hold on our vmspace to
  288          * release their reference.
  289          */
  290         while (p->p_lock > 0)
  291                 msleep(&p->p_lock, &p->p_mtx, PWAIT, "exithold", 0);
  292 
  293         p->p_xstat = rv;        /* Let event handler change exit status */
  294         PROC_UNLOCK(p);
  295         /* Drain the limit callout while we don't have the proc locked */
  296         callout_drain(&p->p_limco);
  297 
  298 #ifdef AUDIT
  299         /*
  300          * The Sun BSM exit token contains two components: an exit status as
  301          * passed to exit(), and a return value to indicate what sort of exit
  302          * it was.  The exit status is WEXITSTATUS(rv), but it's not clear
  303          * what the return value is.
  304          */
  305         AUDIT_ARG_EXIT(WEXITSTATUS(rv), 0);
  306         AUDIT_SYSCALL_EXIT(0, td);
  307 #endif
  308 
  309         /* Are we a task leader? */
  310         if (p == p->p_leader) {
  311                 mtx_lock(&ppeers_lock);
  312                 q = p->p_peers;
  313                 while (q != NULL) {
  314                         PROC_LOCK(q);
  315                         kern_psignal(q, SIGKILL);
  316                         PROC_UNLOCK(q);
  317                         q = q->p_peers;
  318                 }
  319                 while (p->p_peers != NULL)
  320                         msleep(p, &ppeers_lock, PWAIT, "exit1", 0);
  321                 mtx_unlock(&ppeers_lock);
  322         }
  323 
  324         /*
  325          * Check if any loadable modules need anything done at process exit.
  326          * E.g. SYSV IPC stuff
  327          * XXX what if one of these generates an error?
  328          */
  329         EVENTHANDLER_INVOKE(process_exit, p);
  330 
  331         /*
  332          * If parent is waiting for us to exit or exec,
  333          * P_PPWAIT is set; we will wakeup the parent below.
  334          */
  335         PROC_LOCK(p);
  336         rv = p->p_xstat;        /* Event handler could change exit status */
  337         stopprofclock(p);
  338         p->p_flag &= ~(P_TRACED | P_PPWAIT | P_PPTRACE);
  339 
  340         /*
  341          * Stop the real interval timer.  If the handler is currently
  342          * executing, prevent it from rearming itself and let it finish.
  343          */
  344         if (timevalisset(&p->p_realtimer.it_value) &&
  345             callout_stop(&p->p_itcallout) == 0) {
  346                 timevalclear(&p->p_realtimer.it_interval);
  347                 msleep(&p->p_itcallout, &p->p_mtx, PWAIT, "ritwait", 0);
  348                 KASSERT(!timevalisset(&p->p_realtimer.it_value),
  349                     ("realtime timer is still armed"));
  350         }
  351         PROC_UNLOCK(p);
  352 
  353         /*
  354          * Reset any sigio structures pointing to us as a result of
  355          * F_SETOWN with our pid.
  356          */
  357         funsetownlst(&p->p_sigiolst);
  358 
  359         /*
  360          * If this process has an nlminfo data area (for lockd), release it
  361          */
  362         if (nlminfo_release_p != NULL && p->p_nlminfo != NULL)
  363                 (*nlminfo_release_p)(p);
  364 
  365         /*
  366          * Close open files and release open-file table.
  367          * This may block!
  368          */
  369         fdescfree(td);
  370 
  371         /*
  372          * If this thread tickled GEOM, we need to wait for the giggling to
  373          * stop before we return to userland
  374          */
  375         if (td->td_pflags & TDP_GEOM)
  376                 g_waitidle();
  377 
  378         /*
  379          * Remove ourself from our leader's peer list and wake our leader.
  380          */
  381         mtx_lock(&ppeers_lock);
  382         if (p->p_leader->p_peers) {
  383                 q = p->p_leader;
  384                 while (q->p_peers != p)
  385                         q = q->p_peers;
  386                 q->p_peers = p->p_peers;
  387                 wakeup(p->p_leader);
  388         }
  389         mtx_unlock(&ppeers_lock);
  390 
  391         vmspace_exit(td);
  392 
  393         sx_xlock(&proctree_lock);
  394         if (SESS_LEADER(p)) {
  395                 struct session *sp = p->p_session;
  396                 struct tty *tp;
  397 
  398                 /*
  399                  * s_ttyp is not zero'd; we use this to indicate that
  400                  * the session once had a controlling terminal. (for
  401                  * logging and informational purposes)
  402                  */
  403                 SESS_LOCK(sp);
  404                 ttyvp = sp->s_ttyvp;
  405                 tp = sp->s_ttyp;
  406                 sp->s_ttyvp = NULL;
  407                 sp->s_ttydp = NULL;
  408                 sp->s_leader = NULL;
  409                 SESS_UNLOCK(sp);
  410 
  411                 /*
  412                  * Signal foreground pgrp and revoke access to
  413                  * controlling terminal if it has not been revoked
  414                  * already.
  415                  *
  416                  * Because the TTY may have been revoked in the mean
  417                  * time and could already have a new session associated
  418                  * with it, make sure we don't send a SIGHUP to a
  419                  * foreground process group that does not belong to this
  420                  * session.
  421                  */
  422 
  423                 if (tp != NULL) {
  424                         tty_lock(tp);
  425                         if (tp->t_session == sp)
  426                                 tty_signal_pgrp(tp, SIGHUP);
  427                         tty_unlock(tp);
  428                 }
  429 
  430                 if (ttyvp != NULL) {
  431                         sx_xunlock(&proctree_lock);
  432                         if (vn_lock(ttyvp, LK_EXCLUSIVE) == 0) {
  433                                 VOP_REVOKE(ttyvp, REVOKEALL);
  434                                 VOP_UNLOCK(ttyvp, 0);
  435                         }
  436                         sx_xlock(&proctree_lock);
  437                 }
  438         }
  439         fixjobc(p, p->p_pgrp, 0);
  440         sx_xunlock(&proctree_lock);
  441         (void)acct_process(td);
  442 
  443         /* Release the TTY now we've unlocked everything. */
  444         if (ttyvp != NULL)
  445                 vrele(ttyvp);
  446 #ifdef KTRACE
  447         ktrprocexit(td);
  448 #endif
  449         /*
  450          * Release reference to text vnode
  451          */
  452         if (p->p_textvp != NULL) {
  453                 vrele(p->p_textvp);
  454                 p->p_textvp = NULL;
  455         }
  456 
  457         /*
  458          * Release our limits structure.
  459          */
  460         lim_free(p->p_limit);
  461         p->p_limit = NULL;
  462 
  463         tidhash_remove(td);
  464 
  465         /*
  466          * Remove proc from allproc queue and pidhash chain.
  467          * Place onto zombproc.  Unlink from parent's child list.
  468          */
  469         sx_xlock(&allproc_lock);
  470         LIST_REMOVE(p, p_list);
  471         LIST_INSERT_HEAD(&zombproc, p, p_list);
  472         LIST_REMOVE(p, p_hash);
  473         sx_xunlock(&allproc_lock);
  474 
  475         /*
  476          * Call machine-dependent code to release any
  477          * machine-dependent resources other than the address space.
  478          * The address space is released by "vmspace_exitfree(p)" in
  479          * vm_waitproc().
  480          */
  481         cpu_exit(td);
  482 
  483         WITNESS_WARN(WARN_PANIC, NULL, "process (pid %d) exiting", p->p_pid);
  484 
  485         /*
  486          * Reparent all children processes:
  487          * - traced ones to the original parent (or init if we are that parent)
  488          * - the rest to init
  489          */
  490         sx_xlock(&proctree_lock);
  491         q = LIST_FIRST(&p->p_children);
  492         if (q != NULL)          /* only need this if any child is S_ZOMB */
  493                 wakeup(q->p_reaper);
  494         for (; q != NULL; q = nq) {
  495                 nq = LIST_NEXT(q, p_sibling);
  496                 PROC_LOCK(q);
  497                 q->p_sigparent = SIGCHLD;
  498 
  499                 if (!(q->p_flag & P_TRACED)) {
  500                         proc_reparent(q, q->p_reaper);
  501                 } else {
  502                         /*
  503                          * Traced processes are killed since their existence
  504                          * means someone is screwing up.
  505                          */
  506                         t = proc_realparent(q);
  507                         if (t == p) {
  508                                 proc_reparent(q, q->p_reaper);
  509                         } else {
  510                                 PROC_LOCK(t);
  511                                 proc_reparent(q, t);
  512                                 PROC_UNLOCK(t);
  513                         }
  514                         /*
  515                          * Since q was found on our children list, the
  516                          * proc_reparent() call moved q to the orphan
  517                          * list due to present P_TRACED flag. Clear
  518                          * orphan link for q now while q is locked.
  519                          */
  520                         clear_orphan(q);
  521                         q->p_flag &= ~(P_TRACED | P_STOPPED_TRACE);
  522                         FOREACH_THREAD_IN_PROC(q, tdt)
  523                                 tdt->td_dbgflags &= ~TDB_SUSPEND;
  524                         kern_psignal(q, SIGKILL);
  525                 }
  526                 PROC_UNLOCK(q);
  527         }
  528 
  529         /*
  530          * Also get rid of our orphans.
  531          */
  532         while ((q = LIST_FIRST(&p->p_orphans)) != NULL) {
  533                 PROC_LOCK(q);
  534                 CTR2(KTR_PTRACE, "exit: pid %d, clearing orphan %d", p->p_pid,
  535                     q->p_pid);
  536                 clear_orphan(q);
  537                 PROC_UNLOCK(q);
  538         }
  539 
  540         /* Save exit status. */
  541         PROC_LOCK(p);
  542         p->p_xthread = td;
  543 
  544         /* Tell the prison that we are gone. */
  545         prison_proc_free(p->p_ucred->cr_prison);
  546 
  547 #ifdef KDTRACE_HOOKS
  548         /*
  549          * Tell the DTrace fasttrap provider about the exit if it
  550          * has declared an interest.
  551          */
  552         if (dtrace_fasttrap_exit)
  553                 dtrace_fasttrap_exit(p);
  554 #endif
  555 
  556         /*
  557          * Notify interested parties of our demise.
  558          */
  559         KNOTE_LOCKED(&p->p_klist, NOTE_EXIT);
  560 
  561 #ifdef KDTRACE_HOOKS
  562         int reason = CLD_EXITED;
  563         if (WCOREDUMP(rv))
  564                 reason = CLD_DUMPED;
  565         else if (WIFSIGNALED(rv))
  566                 reason = CLD_KILLED;
  567         SDT_PROBE1(proc, kernel, , exit, reason);
  568 #endif
  569 
  570         /*
  571          * Just delete all entries in the p_klist. At this point we won't
  572          * report any more events, and there are nasty race conditions that
  573          * can beat us if we don't.
  574          */
  575         knlist_clear(&p->p_klist, 1);
  576 
  577         /*
  578          * If this is a process with a descriptor, we may not need to deliver
  579          * a signal to the parent.  proctree_lock is held over
  580          * procdesc_exit() to serialize concurrent calls to close() and
  581          * exit().
  582          */
  583 #ifdef PROCDESC
  584         if (p->p_procdesc == NULL || procdesc_exit(p)) {
  585 #endif
  586                 /*
  587                  * Notify parent that we're gone.  If parent has the
  588                  * PS_NOCLDWAIT flag set, or if the handler is set to SIG_IGN,
  589                  * notify process 1 instead (and hope it will handle this
  590                  * situation).
  591                  */
  592                 PROC_LOCK(p->p_pptr);
  593                 mtx_lock(&p->p_pptr->p_sigacts->ps_mtx);
  594                 if (p->p_pptr->p_sigacts->ps_flag &
  595                     (PS_NOCLDWAIT | PS_CLDSIGIGN)) {
  596                         struct proc *pp;
  597 
  598                         mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
  599                         pp = p->p_pptr;
  600                         PROC_UNLOCK(pp);
  601                         proc_reparent(p, p->p_reaper);
  602                         p->p_sigparent = SIGCHLD;
  603                         PROC_LOCK(p->p_pptr);
  604 
  605                         /*
  606                          * Notify parent, so in case he was wait(2)ing or
  607                          * executing waitpid(2) with our pid, he will
  608                          * continue.
  609                          */
  610                         wakeup(pp);
  611                 } else
  612                         mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
  613 
  614                 if (p->p_pptr == p->p_reaper || p->p_pptr == initproc)
  615                         childproc_exited(p);
  616                 else if (p->p_sigparent != 0) {
  617                         if (p->p_sigparent == SIGCHLD)
  618                                 childproc_exited(p);
  619                         else    /* LINUX thread */
  620                                 kern_psignal(p->p_pptr, p->p_sigparent);
  621                 }
  622 #ifdef PROCDESC
  623         } else
  624                 PROC_LOCK(p->p_pptr);
  625 #endif
  626         sx_xunlock(&proctree_lock);
  627 
  628         /*
  629          * The state PRS_ZOMBIE prevents other proesses from sending
  630          * signal to the process, to avoid memory leak, we free memory
  631          * for signal queue at the time when the state is set.
  632          */
  633         sigqueue_flush(&p->p_sigqueue);
  634         sigqueue_flush(&td->td_sigqueue);
  635 
  636         /*
  637          * We have to wait until after acquiring all locks before
  638          * changing p_state.  We need to avoid all possible context
  639          * switches (including ones from blocking on a mutex) while
  640          * marked as a zombie.  We also have to set the zombie state
  641          * before we release the parent process' proc lock to avoid
  642          * a lost wakeup.  So, we first call wakeup, then we grab the
  643          * sched lock, update the state, and release the parent process'
  644          * proc lock.
  645          */
  646         wakeup(p->p_pptr);
  647         cv_broadcast(&p->p_pwait);
  648         sched_exit(p->p_pptr, td);
  649         umtx_thread_exit(td);
  650         PROC_SLOCK(p);
  651         p->p_state = PRS_ZOMBIE;
  652         PROC_UNLOCK(p->p_pptr);
  653 
  654         /*
  655          * Hopefully no one will try to deliver a signal to the process this
  656          * late in the game.
  657          */
  658         knlist_destroy(&p->p_klist);
  659 
  660         /*
  661          * Save our children's rusage information in our exit rusage.
  662          */
  663         PROC_STATLOCK(p);
  664         ruadd(&p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux);
  665         PROC_STATUNLOCK(p);
  666 
  667         /*
  668          * Make sure the scheduler takes this thread out of its tables etc.
  669          * This will also release this thread's reference to the ucred.
  670          * Other thread parts to release include pcb bits and such.
  671          */
  672         thread_exit();
  673 }
  674 
  675 
  676 #ifndef _SYS_SYSPROTO_H_
  677 struct abort2_args {
  678         char *why;
  679         int nargs;
  680         void **args;
  681 };
  682 #endif
  683 
  684 int
  685 sys_abort2(struct thread *td, struct abort2_args *uap)
  686 {
  687         struct proc *p = td->td_proc;
  688         struct sbuf *sb;
  689         void *uargs[16];
  690         int error, i, sig;
  691 
  692         /*
  693          * Do it right now so we can log either proper call of abort2(), or
  694          * note, that invalid argument was passed. 512 is big enough to
  695          * handle 16 arguments' descriptions with additional comments.
  696          */
  697         sb = sbuf_new(NULL, NULL, 512, SBUF_FIXEDLEN);
  698         sbuf_clear(sb);
  699         sbuf_printf(sb, "%s(pid %d uid %d) aborted: ",
  700             p->p_comm, p->p_pid, td->td_ucred->cr_uid);
  701         /*
  702          * Since we can't return from abort2(), send SIGKILL in cases, where
  703          * abort2() was called improperly
  704          */
  705         sig = SIGKILL;
  706         /* Prevent from DoSes from user-space. */
  707         if (uap->nargs < 0 || uap->nargs > 16)
  708                 goto out;
  709         if (uap->nargs > 0) {
  710                 if (uap->args == NULL)
  711                         goto out;
  712                 error = copyin(uap->args, uargs, uap->nargs * sizeof(void *));
  713                 if (error != 0)
  714                         goto out;
  715         }
  716         /*
  717          * Limit size of 'reason' string to 128. Will fit even when
  718          * maximal number of arguments was chosen to be logged.
  719          */
  720         if (uap->why != NULL) {
  721                 error = sbuf_copyin(sb, uap->why, 128);
  722                 if (error < 0)
  723                         goto out;
  724         } else {
  725                 sbuf_printf(sb, "(null)");
  726         }
  727         if (uap->nargs > 0) {
  728                 sbuf_printf(sb, "(");
  729                 for (i = 0;i < uap->nargs; i++)
  730                         sbuf_printf(sb, "%s%p", i == 0 ? "" : ", ", uargs[i]);
  731                 sbuf_printf(sb, ")");
  732         }
  733         /*
  734          * Final stage: arguments were proper, string has been
  735          * successfully copied from userspace, and copying pointers
  736          * from user-space succeed.
  737          */
  738         sig = SIGABRT;
  739 out:
  740         if (sig == SIGKILL) {
  741                 sbuf_trim(sb);
  742                 sbuf_printf(sb, " (Reason text inaccessible)");
  743         }
  744         sbuf_cat(sb, "\n");
  745         sbuf_finish(sb);
  746         log(LOG_INFO, "%s", sbuf_data(sb));
  747         sbuf_delete(sb);
  748         exit1(td, W_EXITCODE(0, sig));
  749         return (0);
  750 }
  751 
  752 
  753 #ifdef COMPAT_43
  754 /*
  755  * The dirty work is handled by kern_wait().
  756  */
  757 int
  758 owait(struct thread *td, struct owait_args *uap __unused)
  759 {
  760         int error, status;
  761 
  762         error = kern_wait(td, WAIT_ANY, &status, 0, NULL);
  763         if (error == 0)
  764                 td->td_retval[1] = status;
  765         return (error);
  766 }
  767 #endif /* COMPAT_43 */
  768 
  769 /*
  770  * The dirty work is handled by kern_wait().
  771  */
  772 int
  773 sys_wait4(struct thread *td, struct wait4_args *uap)
  774 {
  775         struct rusage ru, *rup;
  776         int error, status;
  777 
  778         if (uap->rusage != NULL)
  779                 rup = &ru;
  780         else
  781                 rup = NULL;
  782         error = kern_wait(td, uap->pid, &status, uap->options, rup);
  783         if (uap->status != NULL && error == 0)
  784                 error = copyout(&status, uap->status, sizeof(status));
  785         if (uap->rusage != NULL && error == 0)
  786                 error = copyout(&ru, uap->rusage, sizeof(struct rusage));
  787         return (error);
  788 }
  789 
  790 int
  791 sys_wait6(struct thread *td, struct wait6_args *uap)
  792 {
  793         struct __wrusage wru, *wrup;
  794         siginfo_t si, *sip;
  795         idtype_t idtype;
  796         id_t id;
  797         int error, status;
  798 
  799         idtype = uap->idtype;
  800         id = uap->id;
  801 
  802         if (uap->wrusage != NULL)
  803                 wrup = &wru;
  804         else
  805                 wrup = NULL;
  806 
  807         if (uap->info != NULL) {
  808                 sip = &si;
  809                 bzero(sip, sizeof(*sip));
  810         } else
  811                 sip = NULL;
  812 
  813         /*
  814          *  We expect all callers of wait6() to know about WEXITED and
  815          *  WTRAPPED.
  816          */
  817         error = kern_wait6(td, idtype, id, &status, uap->options, wrup, sip);
  818 
  819         if (uap->status != NULL && error == 0)
  820                 error = copyout(&status, uap->status, sizeof(status));
  821         if (uap->wrusage != NULL && error == 0)
  822                 error = copyout(&wru, uap->wrusage, sizeof(wru));
  823         if (uap->info != NULL && error == 0)
  824                 error = copyout(&si, uap->info, sizeof(si));
  825         return (error);
  826 }
  827 
  828 /*
  829  * Reap the remains of a zombie process and optionally return status and
  830  * rusage.  Asserts and will release both the proctree_lock and the process
  831  * lock as part of its work.
  832  */
  833 void
  834 proc_reap(struct thread *td, struct proc *p, int *status, int options)
  835 {
  836         struct proc *q, *t;
  837 
  838         sx_assert(&proctree_lock, SA_XLOCKED);
  839         PROC_LOCK_ASSERT(p, MA_OWNED);
  840         PROC_SLOCK_ASSERT(p, MA_OWNED);
  841         KASSERT(p->p_state == PRS_ZOMBIE, ("proc_reap: !PRS_ZOMBIE"));
  842 
  843         q = td->td_proc;
  844 
  845         PROC_SUNLOCK(p);
  846         td->td_retval[0] = p->p_pid;
  847         if (status)
  848                 *status = p->p_xstat;   /* convert to int */
  849         if (options & WNOWAIT) {
  850                 /*
  851                  *  Only poll, returning the status.  Caller does not wish to
  852                  * release the proc struct just yet.
  853                  */
  854                 PROC_UNLOCK(p);
  855                 sx_xunlock(&proctree_lock);
  856                 return;
  857         }
  858 
  859         PROC_LOCK(q);
  860         sigqueue_take(p->p_ksi);
  861         PROC_UNLOCK(q);
  862 
  863         /*
  864          * If we got the child via a ptrace 'attach', we need to give it back
  865          * to the old parent.
  866          */
  867         if (p->p_oppid != 0 && p->p_oppid != p->p_pptr->p_pid) {
  868                 PROC_UNLOCK(p);
  869                 t = proc_realparent(p);
  870                 PROC_LOCK(t);
  871                 PROC_LOCK(p);
  872                 CTR2(KTR_PTRACE,
  873                     "wait: traced child %d moved back to parent %d", p->p_pid,
  874                     t->p_pid);
  875                 proc_reparent(p, t);
  876                 p->p_oppid = 0;
  877                 PROC_UNLOCK(p);
  878                 pksignal(t, SIGCHLD, p->p_ksi);
  879                 wakeup(t);
  880                 cv_broadcast(&p->p_pwait);
  881                 PROC_UNLOCK(t);
  882                 sx_xunlock(&proctree_lock);
  883                 return;
  884         }
  885         p->p_oppid = 0;
  886         PROC_UNLOCK(p);
  887 
  888         /*
  889          * Remove other references to this process to ensure we have an
  890          * exclusive reference.
  891          */
  892         sx_xlock(&allproc_lock);
  893         LIST_REMOVE(p, p_list); /* off zombproc */
  894         sx_xunlock(&allproc_lock);
  895         LIST_REMOVE(p, p_sibling);
  896         reaper_abandon_children(p, true);
  897         LIST_REMOVE(p, p_reapsibling);
  898         PROC_LOCK(p);
  899         clear_orphan(p);
  900         PROC_UNLOCK(p);
  901         leavepgrp(p);
  902 #ifdef PROCDESC
  903         if (p->p_procdesc != NULL)
  904                 procdesc_reap(p);
  905 #endif
  906         sx_xunlock(&proctree_lock);
  907 
  908         /*
  909          * As a side effect of this lock, we know that all other writes to
  910          * this proc are visible now, so no more locking is needed for p.
  911          */
  912         PROC_LOCK(p);
  913         p->p_xstat = 0;         /* XXX: why? */
  914         PROC_UNLOCK(p);
  915         PROC_LOCK(q);
  916         ruadd(&q->p_stats->p_cru, &q->p_crux, &p->p_ru, &p->p_rux);
  917         PROC_UNLOCK(q);
  918 
  919         /*
  920          * Decrement the count of procs running with this uid.
  921          */
  922         (void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
  923 
  924         /*
  925          * Destroy resource accounting information associated with the process.
  926          */
  927 #ifdef RACCT
  928         if (racct_enable) {
  929                 PROC_LOCK(p);
  930                 racct_sub(p, RACCT_NPROC, 1);
  931                 PROC_UNLOCK(p);
  932         }
  933 #endif
  934         racct_proc_exit(p);
  935 
  936         /*
  937          * Free credentials, arguments, and sigacts.
  938          */
  939         crfree(p->p_ucred);
  940         p->p_ucred = NULL;
  941         pargs_drop(p->p_args);
  942         p->p_args = NULL;
  943         sigacts_free(p->p_sigacts);
  944         p->p_sigacts = NULL;
  945 
  946         /*
  947          * Do any thread-system specific cleanups.
  948          */
  949         thread_wait(p);
  950 
  951         /*
  952          * Give vm and machine-dependent layer a chance to free anything that
  953          * cpu_exit couldn't release while still running in process context.
  954          */
  955         vm_waitproc(p);
  956 #ifdef MAC
  957         mac_proc_destroy(p);
  958 #endif
  959         KASSERT(FIRST_THREAD_IN_PROC(p),
  960             ("proc_reap: no residual thread!"));
  961         uma_zfree(proc_zone, p);
  962         atomic_add_int(&nprocs, -1);
  963 }
  964 
  965 static int
  966 proc_to_reap(struct thread *td, struct proc *p, idtype_t idtype, id_t id,
  967     int *status, int options, struct __wrusage *wrusage, siginfo_t *siginfo,
  968     int check_only)
  969 {
  970         struct rusage *rup;
  971 
  972         sx_assert(&proctree_lock, SA_XLOCKED);
  973 
  974         PROC_LOCK(p);
  975 
  976         switch (idtype) {
  977         case P_ALL:
  978                 break;
  979         case P_PID:
  980                 if (p->p_pid != (pid_t)id) {
  981                         PROC_UNLOCK(p);
  982                         return (0);
  983                 }
  984                 break;
  985         case P_PGID:
  986                 if (p->p_pgid != (pid_t)id) {
  987                         PROC_UNLOCK(p);
  988                         return (0);
  989                 }
  990                 break;
  991         case P_SID:
  992                 if (p->p_session->s_sid != (pid_t)id) {
  993                         PROC_UNLOCK(p);
  994                         return (0);
  995                 }
  996                 break;
  997         case P_UID:
  998                 if (p->p_ucred->cr_uid != (uid_t)id) {
  999                         PROC_UNLOCK(p);
 1000                         return (0);
 1001                 }
 1002                 break;
 1003         case P_GID:
 1004                 if (p->p_ucred->cr_gid != (gid_t)id) {
 1005                         PROC_UNLOCK(p);
 1006                         return (0);
 1007                 }
 1008                 break;
 1009         case P_JAILID:
 1010                 if (p->p_ucred->cr_prison->pr_id != (int)id) {
 1011                         PROC_UNLOCK(p);
 1012                         return (0);
 1013                 }
 1014                 break;
 1015         /*
 1016          * It seems that the thread structures get zeroed out
 1017          * at process exit.  This makes it impossible to
 1018          * support P_SETID, P_CID or P_CPUID.
 1019          */
 1020         default:
 1021                 PROC_UNLOCK(p);
 1022                 return (0);
 1023         }
 1024 
 1025         if (p_canwait(td, p)) {
 1026                 PROC_UNLOCK(p);
 1027                 return (0);
 1028         }
 1029 
 1030         if (((options & WEXITED) == 0) && (p->p_state == PRS_ZOMBIE)) {
 1031                 PROC_UNLOCK(p);
 1032                 return (0);
 1033         }
 1034 
 1035         /*
 1036          * This special case handles a kthread spawned by linux_clone
 1037          * (see linux_misc.c).  The linux_wait4 and linux_waitpid
 1038          * functions need to be able to distinguish between waiting
 1039          * on a process and waiting on a thread.  It is a thread if
 1040          * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
 1041          * signifies we want to wait for threads and not processes.
 1042          */
 1043         if ((p->p_sigparent != SIGCHLD) ^
 1044             ((options & WLINUXCLONE) != 0)) {
 1045                 PROC_UNLOCK(p);
 1046                 return (0);
 1047         }
 1048 
 1049         if (siginfo != NULL) {
 1050                 bzero(siginfo, sizeof(*siginfo));
 1051                 siginfo->si_errno = 0;
 1052 
 1053                 /*
 1054                  * SUSv4 requires that the si_signo value is always
 1055                  * SIGCHLD. Obey it despite the rfork(2) interface
 1056                  * allows to request other signal for child exit
 1057                  * notification.
 1058                  */
 1059                 siginfo->si_signo = SIGCHLD;
 1060 
 1061                 /*
 1062                  *  This is still a rough estimate.  We will fix the
 1063                  *  cases TRAPPED, STOPPED, and CONTINUED later.
 1064                  */
 1065                 if (WCOREDUMP(p->p_xstat)) {
 1066                         siginfo->si_code = CLD_DUMPED;
 1067                         siginfo->si_status = WTERMSIG(p->p_xstat);
 1068                 } else if (WIFSIGNALED(p->p_xstat)) {
 1069                         siginfo->si_code = CLD_KILLED;
 1070                         siginfo->si_status = WTERMSIG(p->p_xstat);
 1071                 } else {
 1072                         siginfo->si_code = CLD_EXITED;
 1073                         siginfo->si_status = WEXITSTATUS(p->p_xstat);
 1074                 }
 1075 
 1076                 siginfo->si_pid = p->p_pid;
 1077                 siginfo->si_uid = p->p_ucred->cr_uid;
 1078 
 1079                 /*
 1080                  * The si_addr field would be useful additional
 1081                  * detail, but apparently the PC value may be lost
 1082                  * when we reach this point.  bzero() above sets
 1083                  * siginfo->si_addr to NULL.
 1084                  */
 1085         }
 1086 
 1087         /*
 1088          * There should be no reason to limit resources usage info to
 1089          * exited processes only.  A snapshot about any resources used
 1090          * by a stopped process may be exactly what is needed.
 1091          */
 1092         if (wrusage != NULL) {
 1093                 rup = &wrusage->wru_self;
 1094                 *rup = p->p_ru;
 1095                 PROC_STATLOCK(p);
 1096                 calcru(p, &rup->ru_utime, &rup->ru_stime);
 1097                 PROC_STATUNLOCK(p);
 1098 
 1099                 rup = &wrusage->wru_children;
 1100                 *rup = p->p_stats->p_cru;
 1101                 calccru(p, &rup->ru_utime, &rup->ru_stime);
 1102         }
 1103 
 1104         if (p->p_state == PRS_ZOMBIE && !check_only) {
 1105                 PROC_SLOCK(p);
 1106                 proc_reap(td, p, status, options);
 1107                 return (-1);
 1108         }
 1109         PROC_UNLOCK(p);
 1110         return (1);
 1111 }
 1112 
 1113 int
 1114 kern_wait(struct thread *td, pid_t pid, int *status, int options,
 1115     struct rusage *rusage)
 1116 {
 1117         struct __wrusage wru, *wrup;
 1118         idtype_t idtype;
 1119         id_t id;
 1120         int ret;
 1121 
 1122         /*
 1123          * Translate the special pid values into the (idtype, pid)
 1124          * pair for kern_wait6.  The WAIT_MYPGRP case is handled by
 1125          * kern_wait6() on its own.
 1126          */
 1127         if (pid == WAIT_ANY) {
 1128                 idtype = P_ALL;
 1129                 id = 0;
 1130         } else if (pid < 0) {
 1131                 idtype = P_PGID;
 1132                 id = (id_t)-pid;
 1133         } else {
 1134                 idtype = P_PID;
 1135                 id = (id_t)pid;
 1136         }
 1137 
 1138         if (rusage != NULL)
 1139                 wrup = &wru;
 1140         else
 1141                 wrup = NULL;
 1142 
 1143         /*
 1144          * For backward compatibility we implicitly add flags WEXITED
 1145          * and WTRAPPED here.
 1146          */
 1147         options |= WEXITED | WTRAPPED;
 1148         ret = kern_wait6(td, idtype, id, status, options, wrup, NULL);
 1149         if (rusage != NULL)
 1150                 *rusage = wru.wru_self;
 1151         return (ret);
 1152 }
 1153 
 1154 int
 1155 kern_wait6(struct thread *td, idtype_t idtype, id_t id, int *status,
 1156     int options, struct __wrusage *wrusage, siginfo_t *siginfo)
 1157 {
 1158         struct proc *p, *q;
 1159         int error, nfound, ret;
 1160 
 1161         AUDIT_ARG_VALUE((int)idtype);   /* XXX - This is likely wrong! */
 1162         AUDIT_ARG_PID((pid_t)id);       /* XXX - This may be wrong! */
 1163         AUDIT_ARG_VALUE(options);
 1164 
 1165         q = td->td_proc;
 1166 
 1167         if ((pid_t)id == WAIT_MYPGRP && (idtype == P_PID || idtype == P_PGID)) {
 1168                 PROC_LOCK(q);
 1169                 id = (id_t)q->p_pgid;
 1170                 PROC_UNLOCK(q);
 1171                 idtype = P_PGID;
 1172         }
 1173 
 1174         /* If we don't know the option, just return. */
 1175         if ((options & ~(WUNTRACED | WNOHANG | WCONTINUED | WNOWAIT |
 1176             WEXITED | WTRAPPED | WLINUXCLONE)) != 0)
 1177                 return (EINVAL);
 1178         if ((options & (WEXITED | WUNTRACED | WCONTINUED | WTRAPPED)) == 0) {
 1179                 /*
 1180                  * We will be unable to find any matching processes,
 1181                  * because there are no known events to look for.
 1182                  * Prefer to return error instead of blocking
 1183                  * indefinitely.
 1184                  */
 1185                 return (EINVAL);
 1186         }
 1187 
 1188 loop:
 1189         if (q->p_flag & P_STATCHILD) {
 1190                 PROC_LOCK(q);
 1191                 q->p_flag &= ~P_STATCHILD;
 1192                 PROC_UNLOCK(q);
 1193         }
 1194         nfound = 0;
 1195         sx_xlock(&proctree_lock);
 1196         LIST_FOREACH(p, &q->p_children, p_sibling) {
 1197                 ret = proc_to_reap(td, p, idtype, id, status, options,
 1198                     wrusage, siginfo, 0);
 1199                 if (ret == 0)
 1200                         continue;
 1201                 else if (ret == 1)
 1202                         nfound++;
 1203                 else
 1204                         return (0);
 1205 
 1206                 PROC_LOCK(p);
 1207                 PROC_SLOCK(p);
 1208 
 1209                 if ((options & WTRAPPED) != 0 &&
 1210                     (p->p_flag & P_TRACED) != 0 &&
 1211                     (p->p_flag & (P_STOPPED_TRACE | P_STOPPED_SIG)) != 0 &&
 1212                     (p->p_suspcount == p->p_numthreads) &&
 1213                     ((p->p_flag & P_WAITED) == 0)) {
 1214                         PROC_SUNLOCK(p);
 1215                         if ((options & WNOWAIT) == 0)
 1216                                 p->p_flag |= P_WAITED;
 1217                         sx_xunlock(&proctree_lock);
 1218                         td->td_retval[0] = p->p_pid;
 1219 
 1220                         if (status != NULL)
 1221                                 *status = W_STOPCODE(p->p_xstat);
 1222                         if (siginfo != NULL) {
 1223                                 siginfo->si_status = p->p_xstat;
 1224                                 siginfo->si_code = CLD_TRAPPED;
 1225                         }
 1226                         if ((options & WNOWAIT) == 0) {
 1227                                 PROC_LOCK(q);
 1228                                 sigqueue_take(p->p_ksi);
 1229                                 PROC_UNLOCK(q);
 1230                         }
 1231 
 1232                         CTR4(KTR_PTRACE,
 1233             "wait: returning trapped pid %d status %#x (xstat %d) xthread %d",
 1234                             p->p_pid, W_STOPCODE(p->p_xstat), p->p_xstat,
 1235                             p->p_xthread != NULL ? p->p_xthread->td_tid : -1);
 1236                         PROC_UNLOCK(p);
 1237                         return (0);
 1238                 }
 1239                 if ((options & WUNTRACED) != 0 &&
 1240                     (p->p_flag & P_STOPPED_SIG) != 0 &&
 1241                     (p->p_suspcount == p->p_numthreads) &&
 1242                     ((p->p_flag & P_WAITED) == 0)) {
 1243                         PROC_SUNLOCK(p);
 1244                         if ((options & WNOWAIT) == 0)
 1245                                 p->p_flag |= P_WAITED;
 1246                         sx_xunlock(&proctree_lock);
 1247                         td->td_retval[0] = p->p_pid;
 1248 
 1249                         if (status != NULL)
 1250                                 *status = W_STOPCODE(p->p_xstat);
 1251                         if (siginfo != NULL) {
 1252                                 siginfo->si_status = p->p_xstat;
 1253                                 siginfo->si_code = CLD_STOPPED;
 1254                         }
 1255                         if ((options & WNOWAIT) == 0) {
 1256                                 PROC_LOCK(q);
 1257                                 sigqueue_take(p->p_ksi);
 1258                                 PROC_UNLOCK(q);
 1259                         }
 1260 
 1261                         PROC_UNLOCK(p);
 1262                         return (0);
 1263                 }
 1264                 PROC_SUNLOCK(p);
 1265                 if ((options & WCONTINUED) != 0 &&
 1266                     (p->p_flag & P_CONTINUED) != 0) {
 1267                         sx_xunlock(&proctree_lock);
 1268                         td->td_retval[0] = p->p_pid;
 1269                         if ((options & WNOWAIT) == 0) {
 1270                                 p->p_flag &= ~P_CONTINUED;
 1271                                 PROC_LOCK(q);
 1272                                 sigqueue_take(p->p_ksi);
 1273                                 PROC_UNLOCK(q);
 1274                         }
 1275                         PROC_UNLOCK(p);
 1276 
 1277                         if (status != NULL)
 1278                                 *status = SIGCONT;
 1279                         if (siginfo != NULL) {
 1280                                 siginfo->si_status = SIGCONT;
 1281                                 siginfo->si_code = CLD_CONTINUED;
 1282                         }
 1283                         return (0);
 1284                 }
 1285                 PROC_UNLOCK(p);
 1286         }
 1287 
 1288         /*
 1289          * Look in the orphans list too, to allow the parent to
 1290          * collect it's child exit status even if child is being
 1291          * debugged.
 1292          *
 1293          * Debugger detaches from the parent upon successful
 1294          * switch-over from parent to child.  At this point due to
 1295          * re-parenting the parent loses the child to debugger and a
 1296          * wait4(2) call would report that it has no children to wait
 1297          * for.  By maintaining a list of orphans we allow the parent
 1298          * to successfully wait until the child becomes a zombie.
 1299          */
 1300         if (nfound == 0) {
 1301                 LIST_FOREACH(p, &q->p_orphans, p_orphan) {
 1302                         ret = proc_to_reap(td, p, idtype, id, NULL, options,
 1303                             NULL, NULL, 1);
 1304                         if (ret != 0) {
 1305                                 KASSERT(ret != -1, ("reaped an orphan (pid %d)",
 1306                                     (int)td->td_retval[0]));
 1307                                 nfound++;
 1308                                 break;
 1309                         }
 1310                 }
 1311         }
 1312         if (nfound == 0) {
 1313                 sx_xunlock(&proctree_lock);
 1314                 return (ECHILD);
 1315         }
 1316         if (options & WNOHANG) {
 1317                 sx_xunlock(&proctree_lock);
 1318                 td->td_retval[0] = 0;
 1319                 return (0);
 1320         }
 1321         PROC_LOCK(q);
 1322         sx_xunlock(&proctree_lock);
 1323         if (q->p_flag & P_STATCHILD) {
 1324                 q->p_flag &= ~P_STATCHILD;
 1325                 error = 0;
 1326         } else
 1327                 error = msleep(q, &q->p_mtx, PWAIT | PCATCH, "wait", 0);
 1328         PROC_UNLOCK(q);
 1329         if (error)
 1330                 return (error);
 1331         goto loop;
 1332 }
 1333 
 1334 /*
 1335  * Make process 'parent' the new parent of process 'child'.
 1336  * Must be called with an exclusive hold of proctree lock.
 1337  */
 1338 void
 1339 proc_reparent(struct proc *child, struct proc *parent)
 1340 {
 1341 
 1342         sx_assert(&proctree_lock, SX_XLOCKED);
 1343         PROC_LOCK_ASSERT(child, MA_OWNED);
 1344         if (child->p_pptr == parent)
 1345                 return;
 1346 
 1347         PROC_LOCK(child->p_pptr);
 1348         sigqueue_take(child->p_ksi);
 1349         PROC_UNLOCK(child->p_pptr);
 1350         LIST_REMOVE(child, p_sibling);
 1351         LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
 1352 
 1353         clear_orphan(child);
 1354         if (child->p_flag & P_TRACED) {
 1355                 if (LIST_EMPTY(&child->p_pptr->p_orphans)) {
 1356                         child->p_treeflag |= P_TREE_FIRST_ORPHAN;
 1357                         LIST_INSERT_HEAD(&child->p_pptr->p_orphans, child,
 1358                             p_orphan);
 1359                 } else {
 1360                         LIST_INSERT_AFTER(LIST_FIRST(&child->p_pptr->p_orphans),
 1361                             child, p_orphan);
 1362                 }
 1363                 child->p_treeflag |= P_TREE_ORPHANED;
 1364         }
 1365 
 1366         child->p_pptr = parent;
 1367 }

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