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("$FreeBSD$");
   39 
   40 #include "opt_compat.h"
   41 #include "opt_ktrace.h"
   42 
   43 #include <sys/param.h>
   44 #include <sys/systm.h>
   45 #include <sys/sysproto.h>
   46 #include <sys/capsicum.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/procdesc.h>
   54 #include <sys/pioctl.h>
   55 #include <sys/jail.h>
   56 #include <sys/tty.h>
   57 #include <sys/wait.h>
   58 #include <sys/vmmeter.h>
   59 #include <sys/vnode.h>
   60 #include <sys/racct.h>
   61 #include <sys/resourcevar.h>
   62 #include <sys/sbuf.h>
   63 #include <sys/signalvar.h>
   64 #include <sys/sched.h>
   65 #include <sys/sx.h>
   66 #include <sys/syscallsubr.h>
   67 #include <sys/syslog.h>
   68 #include <sys/ptrace.h>
   69 #include <sys/acct.h>           /* for acct_process() function prototype */
   70 #include <sys/filedesc.h>
   71 #include <sys/sdt.h>
   72 #include <sys/shm.h>
   73 #include <sys/sem.h>
   74 #include <sys/umtx.h>
   75 #ifdef KTRACE
   76 #include <sys/ktrace.h>
   77 #endif
   78 
   79 #include <security/audit/audit.h>
   80 #include <security/mac/mac_framework.h>
   81 
   82 #include <vm/vm.h>
   83 #include <vm/vm_extern.h>
   84 #include <vm/vm_param.h>
   85 #include <vm/pmap.h>
   86 #include <vm/vm_map.h>
   87 #include <vm/vm_page.h>
   88 #include <vm/uma.h>
   89 #include <vm/vm_domain.h>
   90 
   91 #ifdef KDTRACE_HOOKS
   92 #include <sys/dtrace_bsd.h>
   93 dtrace_execexit_func_t  dtrace_fasttrap_exit;
   94 #endif
   95 
   96 SDT_PROVIDER_DECLARE(proc);
   97 SDT_PROBE_DEFINE1(proc, , , exit, "int");
   98 
   99 /* Hook for NFS teardown procedure. */
  100 void (*nlminfo_release_p)(struct proc *p);
  101 
  102 EVENTHANDLER_LIST_DECLARE(process_exit);
  103 
  104 struct proc *
  105 proc_realparent(struct proc *child)
  106 {
  107         struct proc *p, *parent;
  108 
  109         sx_assert(&proctree_lock, SX_LOCKED);
  110         if ((child->p_treeflag & P_TREE_ORPHANED) == 0) {
  111                 if (child->p_oppid == 0 ||
  112                     child->p_pptr->p_pid == child->p_oppid)
  113                         parent = child->p_pptr;
  114                 else
  115                         parent = initproc;
  116                 return (parent);
  117         }
  118         for (p = child; (p->p_treeflag & P_TREE_FIRST_ORPHAN) == 0;) {
  119                 /* Cannot use LIST_PREV(), since the list head is not known. */
  120                 p = __containerof(p->p_orphan.le_prev, struct proc,
  121                     p_orphan.le_next);
  122                 KASSERT((p->p_treeflag & P_TREE_ORPHANED) != 0,
  123                     ("missing P_ORPHAN %p", p));
  124         }
  125         parent = __containerof(p->p_orphan.le_prev, struct proc,
  126             p_orphans.lh_first);
  127         return (parent);
  128 }
  129 
  130 void
  131 reaper_abandon_children(struct proc *p, bool exiting)
  132 {
  133         struct proc *p1, *p2, *ptmp;
  134 
  135         sx_assert(&proctree_lock, SX_LOCKED);
  136         KASSERT(p != initproc, ("reaper_abandon_children for initproc"));
  137         if ((p->p_treeflag & P_TREE_REAPER) == 0)
  138                 return;
  139         p1 = p->p_reaper;
  140         LIST_FOREACH_SAFE(p2, &p->p_reaplist, p_reapsibling, ptmp) {
  141                 LIST_REMOVE(p2, p_reapsibling);
  142                 p2->p_reaper = p1;
  143                 p2->p_reapsubtree = p->p_reapsubtree;
  144                 LIST_INSERT_HEAD(&p1->p_reaplist, p2, p_reapsibling);
  145                 if (exiting && p2->p_pptr == p) {
  146                         PROC_LOCK(p2);
  147                         proc_reparent(p2, p1);
  148                         PROC_UNLOCK(p2);
  149                 }
  150         }
  151         KASSERT(LIST_EMPTY(&p->p_reaplist), ("p_reaplist not empty"));
  152         p->p_treeflag &= ~P_TREE_REAPER;
  153 }
  154 
  155 static void
  156 clear_orphan(struct proc *p)
  157 {
  158         struct proc *p1;
  159 
  160         sx_assert(&proctree_lock, SA_XLOCKED);
  161         if ((p->p_treeflag & P_TREE_ORPHANED) == 0)
  162                 return;
  163         if ((p->p_treeflag & P_TREE_FIRST_ORPHAN) != 0) {
  164                 p1 = LIST_NEXT(p, p_orphan);
  165                 if (p1 != NULL)
  166                         p1->p_treeflag |= P_TREE_FIRST_ORPHAN;
  167                 p->p_treeflag &= ~P_TREE_FIRST_ORPHAN;
  168         }
  169         LIST_REMOVE(p, p_orphan);
  170         p->p_treeflag &= ~P_TREE_ORPHANED;
  171 }
  172 
  173 /*
  174  * exit -- death of process.
  175  */
  176 void
  177 sys_sys_exit(struct thread *td, struct sys_exit_args *uap)
  178 {
  179 
  180         exit1(td, uap->rval, 0);
  181         /* NOTREACHED */
  182 }
  183 
  184 /*
  185  * Exit: deallocate address space and other resources, change proc state to
  186  * zombie, and unlink proc from allproc and parent's lists.  Save exit status
  187  * and rusage for wait().  Check for child processes and orphan them.
  188  */
  189 void
  190 exit1(struct thread *td, int rval, int signo)
  191 {
  192         struct proc *p, *nq, *q, *t;
  193         struct thread *tdt;
  194         ksiginfo_t *ksi, *ksi1;
  195 
  196         mtx_assert(&Giant, MA_NOTOWNED);
  197         KASSERT(rval == 0 || signo == 0, ("exit1 rv %d sig %d", rval, signo));
  198 
  199         p = td->td_proc;
  200         /*
  201          * XXX in case we're rebooting we just let init die in order to
  202          * work around an unsolved stack overflow seen very late during
  203          * shutdown on sparc64 when the gmirror worker process exists.
  204          */
  205         if (p == initproc && rebooting == 0) {
  206                 printf("init died (signal %d, exit %d)\n", signo, rval);
  207                 panic("Going nowhere without my init!");
  208         }
  209 
  210         /*
  211          * Deref SU mp, since the thread does not return to userspace.
  212          */
  213         td_softdep_cleanup(td);
  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         /* Let event handler change exit status */
  263         p->p_xexit = rval;
  264         p->p_xsig = signo;
  265 
  266         /*
  267          * Wakeup anyone in procfs' PIOCWAIT.  They should have a hold
  268          * on our vmspace, so we should block below until they have
  269          * released their reference to us.  Note that if they have
  270          * requested S_EXIT stops we will block here until they ack
  271          * via PIOCCONT.
  272          */
  273         _STOPEVENT(p, S_EXIT, 0);
  274 
  275         /*
  276          * Ignore any pending request to stop due to a stop signal.
  277          * Once P_WEXIT is set, future requests will be ignored as
  278          * well.
  279          */
  280         p->p_flag &= ~P_STOPPED_SIG;
  281         KASSERT(!P_SHOULDSTOP(p), ("exiting process is stopped"));
  282 
  283         /*
  284          * Note that we are exiting and do another wakeup of anyone in
  285          * PIOCWAIT in case they aren't listening for S_EXIT stops or
  286          * decided to wait again after we told them we are exiting.
  287          */
  288         p->p_flag |= P_WEXIT;
  289         wakeup(&p->p_stype);
  290 
  291         /*
  292          * Wait for any processes that have a hold on our vmspace to
  293          * release their reference.
  294          */
  295         while (p->p_lock > 0)
  296                 msleep(&p->p_lock, &p->p_mtx, PWAIT, "exithold", 0);
  297 
  298         PROC_UNLOCK(p);
  299         /* Drain the limit callout while we don't have the proc locked */
  300         callout_drain(&p->p_limco);
  301 
  302 #ifdef AUDIT
  303         /*
  304          * The Sun BSM exit token contains two components: an exit status as
  305          * passed to exit(), and a return value to indicate what sort of exit
  306          * it was.  The exit status is WEXITSTATUS(rv), but it's not clear
  307          * what the return value is.
  308          */
  309         AUDIT_ARG_EXIT(rval, 0);
  310         AUDIT_SYSCALL_EXIT(0, td);
  311 #endif
  312 
  313         /* Are we a task leader with peers? */
  314         if (p->p_peers != NULL && p == p->p_leader) {
  315                 mtx_lock(&ppeers_lock);
  316                 q = p->p_peers;
  317                 while (q != NULL) {
  318                         PROC_LOCK(q);
  319                         kern_psignal(q, SIGKILL);
  320                         PROC_UNLOCK(q);
  321                         q = q->p_peers;
  322                 }
  323                 while (p->p_peers != NULL)
  324                         msleep(p, &ppeers_lock, PWAIT, "exit1", 0);
  325                 mtx_unlock(&ppeers_lock);
  326         }
  327 
  328         /*
  329          * Check if any loadable modules need anything done at process exit.
  330          * E.g. SYSV IPC stuff.
  331          * Event handler could change exit status.
  332          * XXX what if one of these generates an error?
  333          */
  334         EVENTHANDLER_DIRECT_INVOKE(process_exit, p);
  335 
  336         /*
  337          * If parent is waiting for us to exit or exec,
  338          * P_PPWAIT is set; we will wakeup the parent below.
  339          */
  340         PROC_LOCK(p);
  341         stopprofclock(p);
  342         p->p_flag &= ~(P_TRACED | P_PPWAIT | P_PPTRACE);
  343         p->p_ptevents = 0;
  344 
  345         /*
  346          * Stop the real interval timer.  If the handler is currently
  347          * executing, prevent it from rearming itself and let it finish.
  348          */
  349         if (timevalisset(&p->p_realtimer.it_value) &&
  350             _callout_stop_safe(&p->p_itcallout, CS_EXECUTING, NULL) == 0) {
  351                 timevalclear(&p->p_realtimer.it_interval);
  352                 msleep(&p->p_itcallout, &p->p_mtx, PWAIT, "ritwait", 0);
  353                 KASSERT(!timevalisset(&p->p_realtimer.it_value),
  354                     ("realtime timer is still armed"));
  355         }
  356 
  357         PROC_UNLOCK(p);
  358 
  359         umtx_thread_exit(td);
  360 
  361         /*
  362          * Reset any sigio structures pointing to us as a result of
  363          * F_SETOWN with our pid.
  364          */
  365         funsetownlst(&p->p_sigiolst);
  366 
  367         /*
  368          * If this process has an nlminfo data area (for lockd), release it
  369          */
  370         if (nlminfo_release_p != NULL && p->p_nlminfo != NULL)
  371                 (*nlminfo_release_p)(p);
  372 
  373         /*
  374          * Close open files and release open-file table.
  375          * This may block!
  376          */
  377         fdescfree(td);
  378 
  379         /*
  380          * If this thread tickled GEOM, we need to wait for the giggling to
  381          * stop before we return to userland
  382          */
  383         if (td->td_pflags & TDP_GEOM)
  384                 g_waitidle();
  385 
  386         /*
  387          * Remove ourself from our leader's peer list and wake our leader.
  388          */
  389         if (p->p_leader->p_peers != NULL) {
  390                 mtx_lock(&ppeers_lock);
  391                 if (p->p_leader->p_peers != NULL) {
  392                         q = p->p_leader;
  393                         while (q->p_peers != p)
  394                                 q = q->p_peers;
  395                         q->p_peers = p->p_peers;
  396                         wakeup(p->p_leader);
  397                 }
  398                 mtx_unlock(&ppeers_lock);
  399         }
  400 
  401         vmspace_exit(td);
  402         killjobc();
  403         (void)acct_process(td);
  404 
  405 #ifdef KTRACE
  406         ktrprocexit(td);
  407 #endif
  408         /*
  409          * Release reference to text vnode
  410          */
  411         if (p->p_textvp != NULL) {
  412                 vrele(p->p_textvp);
  413                 p->p_textvp = NULL;
  414         }
  415 
  416         /*
  417          * Release our limits structure.
  418          */
  419         lim_free(p->p_limit);
  420         p->p_limit = NULL;
  421 
  422         tidhash_remove(td);
  423 
  424         /*
  425          * Remove proc from allproc queue and pidhash chain.
  426          * Place onto zombproc.  Unlink from parent's child list.
  427          */
  428         sx_xlock(&allproc_lock);
  429         LIST_REMOVE(p, p_list);
  430         LIST_INSERT_HEAD(&zombproc, p, p_list);
  431         LIST_REMOVE(p, p_hash);
  432         sx_xunlock(&allproc_lock);
  433 
  434         /*
  435          * Call machine-dependent code to release any
  436          * machine-dependent resources other than the address space.
  437          * The address space is released by "vmspace_exitfree(p)" in
  438          * vm_waitproc().
  439          */
  440         cpu_exit(td);
  441 
  442         WITNESS_WARN(WARN_PANIC, NULL, "process (pid %d) exiting", p->p_pid);
  443 
  444         /*
  445          * Reparent all children processes:
  446          * - traced ones to the original parent (or init if we are that parent)
  447          * - the rest to init
  448          */
  449         sx_xlock(&proctree_lock);
  450         q = LIST_FIRST(&p->p_children);
  451         if (q != NULL)          /* only need this if any child is S_ZOMB */
  452                 wakeup(q->p_reaper);
  453         for (; q != NULL; q = nq) {
  454                 nq = LIST_NEXT(q, p_sibling);
  455                 ksi = ksiginfo_alloc(TRUE);
  456                 PROC_LOCK(q);
  457                 q->p_sigparent = SIGCHLD;
  458 
  459                 if (!(q->p_flag & P_TRACED)) {
  460                         proc_reparent(q, q->p_reaper);
  461                         if (q->p_state == PRS_ZOMBIE) {
  462                                 /*
  463                                  * Inform reaper about the reparented
  464                                  * zombie, since wait(2) has something
  465                                  * new to report.  Guarantee queueing
  466                                  * of the SIGCHLD signal, similar to
  467                                  * the _exit() behaviour, by providing
  468                                  * our ksiginfo.  Ksi is freed by the
  469                                  * signal delivery.
  470                                  */
  471                                 if (q->p_ksi == NULL) {
  472                                         ksi1 = NULL;
  473                                 } else {
  474                                         ksiginfo_copy(q->p_ksi, ksi);
  475                                         ksi->ksi_flags |= KSI_INS;
  476                                         ksi1 = ksi;
  477                                         ksi = NULL;
  478                                 }
  479                                 PROC_LOCK(q->p_reaper);
  480                                 pksignal(q->p_reaper, SIGCHLD, ksi1);
  481                                 PROC_UNLOCK(q->p_reaper);
  482                         } else if (q->p_pdeathsig > 0) {
  483                                 /*
  484                                  * The child asked to received a signal
  485                                  * when we exit.
  486                                  */
  487                                 kern_psignal(q, q->p_pdeathsig);
  488                         }
  489                 } else {
  490                         /*
  491                          * Traced processes are killed since their existence
  492                          * means someone is screwing up.
  493                          */
  494                         t = proc_realparent(q);
  495                         if (t == p) {
  496                                 proc_reparent(q, q->p_reaper);
  497                         } else {
  498                                 PROC_LOCK(t);
  499                                 proc_reparent(q, t);
  500                                 PROC_UNLOCK(t);
  501                         }
  502                         /*
  503                          * Since q was found on our children list, the
  504                          * proc_reparent() call moved q to the orphan
  505                          * list due to present P_TRACED flag. Clear
  506                          * orphan link for q now while q is locked.
  507                          */
  508                         clear_orphan(q);
  509                         q->p_flag &= ~(P_TRACED | P_STOPPED_TRACE);
  510                         q->p_flag2 &= ~P2_PTRACE_FSTP;
  511                         q->p_ptevents = 0;
  512                         FOREACH_THREAD_IN_PROC(q, tdt) {
  513                                 tdt->td_dbgflags &= ~(TDB_SUSPEND | TDB_XSIG |
  514                                     TDB_FSTP);
  515                         }
  516                         kern_psignal(q, SIGKILL);
  517                 }
  518                 PROC_UNLOCK(q);
  519                 if (ksi != NULL)
  520                         ksiginfo_free(ksi);
  521         }
  522 
  523         /*
  524          * Also get rid of our orphans.
  525          */
  526         while ((q = LIST_FIRST(&p->p_orphans)) != NULL) {
  527                 PROC_LOCK(q);
  528                 KASSERT(q->p_oppid == p->p_pid,
  529                     ("orphan %p of %p has unexpected oppid %d", q, p,
  530                     q->p_oppid));
  531                 q->p_oppid = q->p_reaper->p_pid;
  532 
  533                 /*
  534                  * If we are the real parent of this process
  535                  * but it has been reparented to a debugger, then
  536                  * check if it asked for a signal when we exit.
  537                  */
  538                 if (q->p_pdeathsig > 0)
  539                         kern_psignal(q, q->p_pdeathsig);
  540                 CTR2(KTR_PTRACE, "exit: pid %d, clearing orphan %d", p->p_pid,
  541                     q->p_pid);
  542                 clear_orphan(q);
  543                 PROC_UNLOCK(q);
  544         }
  545 
  546         /* Save exit status. */
  547         PROC_LOCK(p);
  548         p->p_xthread = td;
  549 
  550         /* Tell the prison that we are gone. */
  551         prison_proc_free(p->p_ucred->cr_prison);
  552 
  553 #ifdef KDTRACE_HOOKS
  554         /*
  555          * Tell the DTrace fasttrap provider about the exit if it
  556          * has declared an interest.
  557          */
  558         if (dtrace_fasttrap_exit)
  559                 dtrace_fasttrap_exit(p);
  560 #endif
  561 
  562         /*
  563          * Notify interested parties of our demise.
  564          */
  565         KNOTE_LOCKED(p->p_klist, NOTE_EXIT);
  566 
  567 #ifdef KDTRACE_HOOKS
  568         int reason = CLD_EXITED;
  569         if (WCOREDUMP(signo))
  570                 reason = CLD_DUMPED;
  571         else if (WIFSIGNALED(signo))
  572                 reason = CLD_KILLED;
  573         SDT_PROBE1(proc, , , exit, reason);
  574 #endif
  575 
  576         /*
  577          * If this is a process with a descriptor, we may not need to deliver
  578          * a signal to the parent.  proctree_lock is held over
  579          * procdesc_exit() to serialize concurrent calls to close() and
  580          * exit().
  581          */
  582         if (p->p_procdesc == NULL || procdesc_exit(p)) {
  583                 /*
  584                  * Notify parent that we're gone.  If parent has the
  585                  * PS_NOCLDWAIT flag set, or if the handler is set to SIG_IGN,
  586                  * notify process 1 instead (and hope it will handle this
  587                  * situation).
  588                  */
  589                 PROC_LOCK(p->p_pptr);
  590                 mtx_lock(&p->p_pptr->p_sigacts->ps_mtx);
  591                 if (p->p_pptr->p_sigacts->ps_flag &
  592                     (PS_NOCLDWAIT | PS_CLDSIGIGN)) {
  593                         struct proc *pp;
  594 
  595                         mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
  596                         pp = p->p_pptr;
  597                         PROC_UNLOCK(pp);
  598                         proc_reparent(p, p->p_reaper);
  599                         p->p_sigparent = SIGCHLD;
  600                         PROC_LOCK(p->p_pptr);
  601 
  602                         /*
  603                          * Notify parent, so in case he was wait(2)ing or
  604                          * executing waitpid(2) with our pid, he will
  605                          * continue.
  606                          */
  607                         wakeup(pp);
  608                 } else
  609                         mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
  610 
  611                 if (p->p_pptr == p->p_reaper || p->p_pptr == initproc)
  612                         childproc_exited(p);
  613                 else if (p->p_sigparent != 0) {
  614                         if (p->p_sigparent == SIGCHLD)
  615                                 childproc_exited(p);
  616                         else    /* LINUX thread */
  617                                 kern_psignal(p->p_pptr, p->p_sigparent);
  618                 }
  619         } else
  620                 PROC_LOCK(p->p_pptr);
  621         sx_xunlock(&proctree_lock);
  622 
  623         /*
  624          * The state PRS_ZOMBIE prevents other proesses from sending
  625          * signal to the process, to avoid memory leak, we free memory
  626          * for signal queue at the time when the state is set.
  627          */
  628         sigqueue_flush(&p->p_sigqueue);
  629         sigqueue_flush(&td->td_sigqueue);
  630 
  631         /*
  632          * We have to wait until after acquiring all locks before
  633          * changing p_state.  We need to avoid all possible context
  634          * switches (including ones from blocking on a mutex) while
  635          * marked as a zombie.  We also have to set the zombie state
  636          * before we release the parent process' proc lock to avoid
  637          * a lost wakeup.  So, we first call wakeup, then we grab the
  638          * sched lock, update the state, and release the parent process'
  639          * proc lock.
  640          */
  641         wakeup(p->p_pptr);
  642         cv_broadcast(&p->p_pwait);
  643         sched_exit(p->p_pptr, td);
  644         PROC_SLOCK(p);
  645         p->p_state = PRS_ZOMBIE;
  646         PROC_UNLOCK(p->p_pptr);
  647 
  648         /*
  649          * Save our children's rusage information in our exit rusage.
  650          */
  651         PROC_STATLOCK(p);
  652         ruadd(&p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux);
  653         PROC_STATUNLOCK(p);
  654 
  655         /*
  656          * Make sure the scheduler takes this thread out of its tables etc.
  657          * This will also release this thread's reference to the ucred.
  658          * Other thread parts to release include pcb bits and such.
  659          */
  660         thread_exit();
  661 }
  662 
  663 
  664 #ifndef _SYS_SYSPROTO_H_
  665 struct abort2_args {
  666         char *why;
  667         int nargs;
  668         void **args;
  669 };
  670 #endif
  671 
  672 int
  673 sys_abort2(struct thread *td, struct abort2_args *uap)
  674 {
  675         struct proc *p = td->td_proc;
  676         struct sbuf *sb;
  677         void *uargs[16];
  678         int error, i, sig;
  679 
  680         /*
  681          * Do it right now so we can log either proper call of abort2(), or
  682          * note, that invalid argument was passed. 512 is big enough to
  683          * handle 16 arguments' descriptions with additional comments.
  684          */
  685         sb = sbuf_new(NULL, NULL, 512, SBUF_FIXEDLEN);
  686         sbuf_clear(sb);
  687         sbuf_printf(sb, "%s(pid %d uid %d) aborted: ",
  688             p->p_comm, p->p_pid, td->td_ucred->cr_uid);
  689         /*
  690          * Since we can't return from abort2(), send SIGKILL in cases, where
  691          * abort2() was called improperly
  692          */
  693         sig = SIGKILL;
  694         /* Prevent from DoSes from user-space. */
  695         if (uap->nargs < 0 || uap->nargs > 16)
  696                 goto out;
  697         if (uap->nargs > 0) {
  698                 if (uap->args == NULL)
  699                         goto out;
  700                 error = copyin(uap->args, uargs, uap->nargs * sizeof(void *));
  701                 if (error != 0)
  702                         goto out;
  703         }
  704         /*
  705          * Limit size of 'reason' string to 128. Will fit even when
  706          * maximal number of arguments was chosen to be logged.
  707          */
  708         if (uap->why != NULL) {
  709                 error = sbuf_copyin(sb, uap->why, 128);
  710                 if (error < 0)
  711                         goto out;
  712         } else {
  713                 sbuf_printf(sb, "(null)");
  714         }
  715         if (uap->nargs > 0) {
  716                 sbuf_printf(sb, "(");
  717                 for (i = 0;i < uap->nargs; i++)
  718                         sbuf_printf(sb, "%s%p", i == 0 ? "" : ", ", uargs[i]);
  719                 sbuf_printf(sb, ")");
  720         }
  721         /*
  722          * Final stage: arguments were proper, string has been
  723          * successfully copied from userspace, and copying pointers
  724          * from user-space succeed.
  725          */
  726         sig = SIGABRT;
  727 out:
  728         if (sig == SIGKILL) {
  729                 sbuf_trim(sb);
  730                 sbuf_printf(sb, " (Reason text inaccessible)");
  731         }
  732         sbuf_cat(sb, "\n");
  733         sbuf_finish(sb);
  734         log(LOG_INFO, "%s", sbuf_data(sb));
  735         sbuf_delete(sb);
  736         exit1(td, 0, sig);
  737         return (0);
  738 }
  739 
  740 
  741 #ifdef COMPAT_43
  742 /*
  743  * The dirty work is handled by kern_wait().
  744  */
  745 int
  746 owait(struct thread *td, struct owait_args *uap __unused)
  747 {
  748         int error, status;
  749 
  750         error = kern_wait(td, WAIT_ANY, &status, 0, NULL);
  751         if (error == 0)
  752                 td->td_retval[1] = status;
  753         return (error);
  754 }
  755 #endif /* COMPAT_43 */
  756 
  757 /*
  758  * The dirty work is handled by kern_wait().
  759  */
  760 int
  761 sys_wait4(struct thread *td, struct wait4_args *uap)
  762 {
  763         struct rusage ru, *rup;
  764         int error, status;
  765 
  766         if (uap->rusage != NULL)
  767                 rup = &ru;
  768         else
  769                 rup = NULL;
  770         error = kern_wait(td, uap->pid, &status, uap->options, rup);
  771         if (uap->status != NULL && error == 0 && td->td_retval[0] != 0)
  772                 error = copyout(&status, uap->status, sizeof(status));
  773         if (uap->rusage != NULL && error == 0 && td->td_retval[0] != 0)
  774                 error = copyout(&ru, uap->rusage, sizeof(struct rusage));
  775         return (error);
  776 }
  777 
  778 int
  779 sys_wait6(struct thread *td, struct wait6_args *uap)
  780 {
  781         struct __wrusage wru, *wrup;
  782         siginfo_t si, *sip;
  783         idtype_t idtype;
  784         id_t id;
  785         int error, status;
  786 
  787         idtype = uap->idtype;
  788         id = uap->id;
  789 
  790         if (uap->wrusage != NULL)
  791                 wrup = &wru;
  792         else
  793                 wrup = NULL;
  794 
  795         if (uap->info != NULL) {
  796                 sip = &si;
  797                 bzero(sip, sizeof(*sip));
  798         } else
  799                 sip = NULL;
  800 
  801         /*
  802          *  We expect all callers of wait6() to know about WEXITED and
  803          *  WTRAPPED.
  804          */
  805         error = kern_wait6(td, idtype, id, &status, uap->options, wrup, sip);
  806 
  807         if (uap->status != NULL && error == 0 && td->td_retval[0] != 0)
  808                 error = copyout(&status, uap->status, sizeof(status));
  809         if (uap->wrusage != NULL && error == 0 && td->td_retval[0] != 0)
  810                 error = copyout(&wru, uap->wrusage, sizeof(wru));
  811         if (uap->info != NULL && error == 0)
  812                 error = copyout(&si, uap->info, sizeof(si));
  813         return (error);
  814 }
  815 
  816 /*
  817  * Reap the remains of a zombie process and optionally return status and
  818  * rusage.  Asserts and will release both the proctree_lock and the process
  819  * lock as part of its work.
  820  */
  821 void
  822 proc_reap(struct thread *td, struct proc *p, int *status, int options)
  823 {
  824         struct proc *q, *t;
  825 
  826         sx_assert(&proctree_lock, SA_XLOCKED);
  827         PROC_LOCK_ASSERT(p, MA_OWNED);
  828         PROC_SLOCK_ASSERT(p, MA_OWNED);
  829         KASSERT(p->p_state == PRS_ZOMBIE, ("proc_reap: !PRS_ZOMBIE"));
  830 
  831         q = td->td_proc;
  832 
  833         PROC_SUNLOCK(p);
  834         if (status)
  835                 *status = KW_EXITCODE(p->p_xexit, p->p_xsig);
  836         if (options & WNOWAIT) {
  837                 /*
  838                  *  Only poll, returning the status.  Caller does not wish to
  839                  * release the proc struct just yet.
  840                  */
  841                 PROC_UNLOCK(p);
  842                 sx_xunlock(&proctree_lock);
  843                 return;
  844         }
  845 
  846         PROC_LOCK(q);
  847         sigqueue_take(p->p_ksi);
  848         PROC_UNLOCK(q);
  849 
  850         /*
  851          * If we got the child via a ptrace 'attach', we need to give it back
  852          * to the old parent.
  853          */
  854         if (p->p_oppid != 0 && p->p_oppid != p->p_pptr->p_pid) {
  855                 PROC_UNLOCK(p);
  856                 t = proc_realparent(p);
  857                 PROC_LOCK(t);
  858                 PROC_LOCK(p);
  859                 CTR2(KTR_PTRACE,
  860                     "wait: traced child %d moved back to parent %d", p->p_pid,
  861                     t->p_pid);
  862                 proc_reparent(p, t);
  863                 p->p_oppid = 0;
  864                 PROC_UNLOCK(p);
  865                 pksignal(t, SIGCHLD, p->p_ksi);
  866                 wakeup(t);
  867                 cv_broadcast(&p->p_pwait);
  868                 PROC_UNLOCK(t);
  869                 sx_xunlock(&proctree_lock);
  870                 return;
  871         }
  872         p->p_oppid = 0;
  873         PROC_UNLOCK(p);
  874 
  875         /*
  876          * Remove other references to this process to ensure we have an
  877          * exclusive reference.
  878          */
  879         sx_xlock(&allproc_lock);
  880         LIST_REMOVE(p, p_list); /* off zombproc */
  881         sx_xunlock(&allproc_lock);
  882         LIST_REMOVE(p, p_sibling);
  883         reaper_abandon_children(p, true);
  884         LIST_REMOVE(p, p_reapsibling);
  885         PROC_LOCK(p);
  886         clear_orphan(p);
  887         PROC_UNLOCK(p);
  888         leavepgrp(p);
  889         if (p->p_procdesc != NULL)
  890                 procdesc_reap(p);
  891         sx_xunlock(&proctree_lock);
  892 
  893         PROC_LOCK(p);
  894         knlist_detach(p->p_klist);
  895         p->p_klist = NULL;
  896         PROC_UNLOCK(p);
  897 
  898         /*
  899          * Removal from allproc list and process group list paired with
  900          * PROC_LOCK which was executed during that time should guarantee
  901          * nothing can reach this process anymore. As such further locking
  902          * is unnecessary.
  903          */
  904         p->p_xexit = p->p_xsig = 0;             /* XXX: why? */
  905 
  906         PROC_LOCK(q);
  907         ruadd(&q->p_stats->p_cru, &q->p_crux, &p->p_ru, &p->p_rux);
  908         PROC_UNLOCK(q);
  909 
  910         /*
  911          * Decrement the count of procs running with this uid.
  912          */
  913         (void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
  914 
  915         /*
  916          * Destroy resource accounting information associated with the process.
  917          */
  918 #ifdef RACCT
  919         if (racct_enable) {
  920                 PROC_LOCK(p);
  921                 racct_sub(p, RACCT_NPROC, 1);
  922                 PROC_UNLOCK(p);
  923         }
  924 #endif
  925         racct_proc_exit(p);
  926 
  927         /*
  928          * Free credentials, arguments, and sigacts.
  929          */
  930         crfree(p->p_ucred);
  931         proc_set_cred(p, NULL);
  932         pargs_drop(p->p_args);
  933         p->p_args = NULL;
  934         sigacts_free(p->p_sigacts);
  935         p->p_sigacts = NULL;
  936 
  937         /*
  938          * Do any thread-system specific cleanups.
  939          */
  940         thread_wait(p);
  941 
  942         /*
  943          * Give vm and machine-dependent layer a chance to free anything that
  944          * cpu_exit couldn't release while still running in process context.
  945          */
  946         vm_waitproc(p);
  947 #ifdef MAC
  948         mac_proc_destroy(p);
  949 #endif
  950         /*
  951          * Free any domain policy that's still hiding around.
  952          */
  953         vm_domain_policy_cleanup(&p->p_vm_dom_policy);
  954 
  955         KASSERT(FIRST_THREAD_IN_PROC(p),
  956             ("proc_reap: no residual thread!"));
  957         uma_zfree(proc_zone, p);
  958         atomic_add_int(&nprocs, -1);
  959 }
  960 
  961 static int
  962 proc_to_reap(struct thread *td, struct proc *p, idtype_t idtype, id_t id,
  963     int *status, int options, struct __wrusage *wrusage, siginfo_t *siginfo,
  964     int check_only)
  965 {
  966         struct rusage *rup;
  967 
  968         sx_assert(&proctree_lock, SA_XLOCKED);
  969 
  970         PROC_LOCK(p);
  971 
  972         switch (idtype) {
  973         case P_ALL:
  974                 if (p->p_procdesc != NULL) {
  975                         PROC_UNLOCK(p);
  976                         return (0);
  977                 }
  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_xsig)) {
 1066                         siginfo->si_code = CLD_DUMPED;
 1067                         siginfo->si_status = WTERMSIG(p->p_xsig);
 1068                 } else if (WIFSIGNALED(p->p_xsig)) {
 1069                         siginfo->si_code = CLD_KILLED;
 1070                         siginfo->si_status = WTERMSIG(p->p_xsig);
 1071                 } else {
 1072                         siginfo->si_code = CLD_EXITED;
 1073                         siginfo->si_status = p->p_xexit;
 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         return (1);
 1110 }
 1111 
 1112 int
 1113 kern_wait(struct thread *td, pid_t pid, int *status, int options,
 1114     struct rusage *rusage)
 1115 {
 1116         struct __wrusage wru, *wrup;
 1117         idtype_t idtype;
 1118         id_t id;
 1119         int ret;
 1120 
 1121         /*
 1122          * Translate the special pid values into the (idtype, pid)
 1123          * pair for kern_wait6.  The WAIT_MYPGRP case is handled by
 1124          * kern_wait6() on its own.
 1125          */
 1126         if (pid == WAIT_ANY) {
 1127                 idtype = P_ALL;
 1128                 id = 0;
 1129         } else if (pid < 0) {
 1130                 idtype = P_PGID;
 1131                 id = (id_t)-pid;
 1132         } else {
 1133                 idtype = P_PID;
 1134                 id = (id_t)pid;
 1135         }
 1136 
 1137         if (rusage != NULL)
 1138                 wrup = &wru;
 1139         else
 1140                 wrup = NULL;
 1141 
 1142         /*
 1143          * For backward compatibility we implicitly add flags WEXITED
 1144          * and WTRAPPED here.
 1145          */
 1146         options |= WEXITED | WTRAPPED;
 1147         ret = kern_wait6(td, idtype, id, status, options, wrup, NULL);
 1148         if (rusage != NULL)
 1149                 *rusage = wru.wru_self;
 1150         return (ret);
 1151 }
 1152 
 1153 static void
 1154 report_alive_proc(struct thread *td, struct proc *p, siginfo_t *siginfo,
 1155     int *status, int options, int si_code)
 1156 {
 1157         bool cont;
 1158 
 1159         PROC_LOCK_ASSERT(p, MA_OWNED);
 1160         sx_assert(&proctree_lock, SA_XLOCKED);
 1161         MPASS(si_code == CLD_TRAPPED || si_code == CLD_STOPPED ||
 1162             si_code == CLD_CONTINUED);
 1163 
 1164         cont = si_code == CLD_CONTINUED;
 1165         if ((options & WNOWAIT) == 0) {
 1166                 if (cont)
 1167                         p->p_flag &= ~P_CONTINUED;
 1168                 else
 1169                         p->p_flag |= P_WAITED;
 1170                 PROC_LOCK(td->td_proc);
 1171                 sigqueue_take(p->p_ksi);
 1172                 PROC_UNLOCK(td->td_proc);
 1173         }
 1174         sx_xunlock(&proctree_lock);
 1175         if (siginfo != NULL) {
 1176                 siginfo->si_code = si_code;
 1177                 siginfo->si_status = cont ? SIGCONT : p->p_xsig;
 1178         }
 1179         if (status != NULL)
 1180                 *status = cont ? SIGCONT : W_STOPCODE(p->p_xsig);
 1181         PROC_UNLOCK(p);
 1182         td->td_retval[0] = p->p_pid;
 1183 }
 1184 
 1185 int
 1186 kern_wait6(struct thread *td, idtype_t idtype, id_t id, int *status,
 1187     int options, struct __wrusage *wrusage, siginfo_t *siginfo)
 1188 {
 1189         struct proc *p, *q;
 1190         pid_t pid;
 1191         int error, nfound, ret;
 1192 
 1193         AUDIT_ARG_VALUE((int)idtype);   /* XXX - This is likely wrong! */
 1194         AUDIT_ARG_PID((pid_t)id);       /* XXX - This may be wrong! */
 1195         AUDIT_ARG_VALUE(options);
 1196 
 1197         q = td->td_proc;
 1198 
 1199         if ((pid_t)id == WAIT_MYPGRP && (idtype == P_PID || idtype == P_PGID)) {
 1200                 PROC_LOCK(q);
 1201                 id = (id_t)q->p_pgid;
 1202                 PROC_UNLOCK(q);
 1203                 idtype = P_PGID;
 1204         }
 1205 
 1206         /* If we don't know the option, just return. */
 1207         if ((options & ~(WUNTRACED | WNOHANG | WCONTINUED | WNOWAIT |
 1208             WEXITED | WTRAPPED | WLINUXCLONE)) != 0)
 1209                 return (EINVAL);
 1210         if ((options & (WEXITED | WUNTRACED | WCONTINUED | WTRAPPED)) == 0) {
 1211                 /*
 1212                  * We will be unable to find any matching processes,
 1213                  * because there are no known events to look for.
 1214                  * Prefer to return error instead of blocking
 1215                  * indefinitely.
 1216                  */
 1217                 return (EINVAL);
 1218         }
 1219 
 1220 loop:
 1221         if (q->p_flag & P_STATCHILD) {
 1222                 PROC_LOCK(q);
 1223                 q->p_flag &= ~P_STATCHILD;
 1224                 PROC_UNLOCK(q);
 1225         }
 1226         nfound = 0;
 1227         sx_xlock(&proctree_lock);
 1228         LIST_FOREACH(p, &q->p_children, p_sibling) {
 1229                 pid = p->p_pid;
 1230                 ret = proc_to_reap(td, p, idtype, id, status, options,
 1231                     wrusage, siginfo, 0);
 1232                 if (ret == 0)
 1233                         continue;
 1234                 else if (ret == 1)
 1235                         nfound++;
 1236                 else {
 1237                         td->td_retval[0] = pid;
 1238                         return (0);
 1239                 }
 1240 
 1241                 PROC_LOCK_ASSERT(p, MA_OWNED);
 1242 
 1243                 if ((options & (WTRAPPED | WUNTRACED)) != 0)
 1244                         PROC_SLOCK(p);
 1245 
 1246                 if ((options & WTRAPPED) != 0 &&
 1247                     (p->p_flag & P_TRACED) != 0 &&
 1248                     (p->p_flag & (P_STOPPED_TRACE | P_STOPPED_SIG)) != 0 &&
 1249                     p->p_suspcount == p->p_numthreads &&
 1250                     (p->p_flag & P_WAITED) == 0) {
 1251                         PROC_SUNLOCK(p);
 1252                         CTR4(KTR_PTRACE,
 1253                             "wait: returning trapped pid %d status %#x "
 1254                             "(xstat %d) xthread %d",
 1255                             p->p_pid, W_STOPCODE(p->p_xsig), p->p_xsig,
 1256                             p->p_xthread != NULL ?
 1257                             p->p_xthread->td_tid : -1);
 1258                         report_alive_proc(td, p, siginfo, status, options,
 1259                             CLD_TRAPPED);
 1260                         return (0);
 1261                         }
 1262                 if ((options & WUNTRACED) != 0 &&
 1263                     (p->p_flag & P_STOPPED_SIG) != 0 &&
 1264                     p->p_suspcount == p->p_numthreads &&
 1265                     (p->p_flag & P_WAITED) == 0) {
 1266                         PROC_SUNLOCK(p);
 1267                         report_alive_proc(td, p, siginfo, status, options,
 1268                             CLD_STOPPED);
 1269                         return (0);
 1270                 }
 1271                 if ((options & (WTRAPPED | WUNTRACED)) != 0)
 1272                         PROC_SUNLOCK(p);
 1273                 if ((options & WCONTINUED) != 0 &&
 1274                     (p->p_flag & P_CONTINUED) != 0) {
 1275                         report_alive_proc(td, p, siginfo, status, options,
 1276                             CLD_CONTINUED);
 1277                         return (0);
 1278                 }
 1279                 PROC_UNLOCK(p);
 1280         }
 1281 
 1282         /*
 1283          * Look in the orphans list too, to allow the parent to
 1284          * collect it's child exit status even if child is being
 1285          * debugged.
 1286          *
 1287          * Debugger detaches from the parent upon successful
 1288          * switch-over from parent to child.  At this point due to
 1289          * re-parenting the parent loses the child to debugger and a
 1290          * wait4(2) call would report that it has no children to wait
 1291          * for.  By maintaining a list of orphans we allow the parent
 1292          * to successfully wait until the child becomes a zombie.
 1293          */
 1294         if (nfound == 0) {
 1295                 LIST_FOREACH(p, &q->p_orphans, p_orphan) {
 1296                         ret = proc_to_reap(td, p, idtype, id, NULL, options,
 1297                             NULL, NULL, 1);
 1298                         if (ret != 0) {
 1299                                 KASSERT(ret != -1, ("reaped an orphan (pid %d)",
 1300                                     (int)td->td_retval[0]));
 1301                                 PROC_UNLOCK(p);
 1302                                 nfound++;
 1303                                 break;
 1304                         }
 1305                 }
 1306         }
 1307         if (nfound == 0) {
 1308                 sx_xunlock(&proctree_lock);
 1309                 return (ECHILD);
 1310         }
 1311         if (options & WNOHANG) {
 1312                 sx_xunlock(&proctree_lock);
 1313                 td->td_retval[0] = 0;
 1314                 return (0);
 1315         }
 1316         PROC_LOCK(q);
 1317         sx_xunlock(&proctree_lock);
 1318         if (q->p_flag & P_STATCHILD) {
 1319                 q->p_flag &= ~P_STATCHILD;
 1320                 error = 0;
 1321         } else
 1322                 error = msleep(q, &q->p_mtx, PWAIT | PCATCH, "wait", 0);
 1323         PROC_UNLOCK(q);
 1324         if (error)
 1325                 return (error);
 1326         goto loop;
 1327 }
 1328 
 1329 /*
 1330  * Make process 'parent' the new parent of process 'child'.
 1331  * Must be called with an exclusive hold of proctree lock.
 1332  */
 1333 void
 1334 proc_reparent(struct proc *child, struct proc *parent)
 1335 {
 1336 
 1337         sx_assert(&proctree_lock, SX_XLOCKED);
 1338         PROC_LOCK_ASSERT(child, MA_OWNED);
 1339         if (child->p_pptr == parent)
 1340                 return;
 1341 
 1342         PROC_LOCK(child->p_pptr);
 1343         sigqueue_take(child->p_ksi);
 1344         PROC_UNLOCK(child->p_pptr);
 1345         LIST_REMOVE(child, p_sibling);
 1346         LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
 1347 
 1348         clear_orphan(child);
 1349         if (child->p_flag & P_TRACED) {
 1350                 if (LIST_EMPTY(&child->p_pptr->p_orphans)) {
 1351                         child->p_treeflag |= P_TREE_FIRST_ORPHAN;
 1352                         LIST_INSERT_HEAD(&child->p_pptr->p_orphans, child,
 1353                             p_orphan);
 1354                 } else {
 1355                         LIST_INSERT_AFTER(LIST_FIRST(&child->p_pptr->p_orphans),
 1356                             child, p_orphan);
 1357                 }
 1358                 child->p_treeflag |= P_TREE_ORPHANED;
 1359         }
 1360 
 1361         child->p_pptr = parent;
 1362 }

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