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

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 1982, 1986, 1989, 1991, 1993
      *      The Regents of the University of California.  All rights reserved.
      * (c) UNIX System Laboratories, Inc.
      * All or some portions of this file are derived from material licensed
      * to the University of California by American Telephone and Telegraph
      * Co. or Unix System Laboratories, Inc. and are reproduced herein with
     * the permission of UNIX System Laboratories, Inc.
     *
     * Redistribution and use in source and binary forms, with or without
     * modification, are permitted provided that the following conditions
     * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      @(#)kern_exit.c 8.7 (Berkeley) 2/12/94
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include "opt_ddb.h"
    #include "opt_ktrace.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/sysproto.h>
    #include <sys/capsicum.h>
    #include <sys/eventhandler.h>
    #include <sys/kernel.h>
    #include <sys/ktr.h>
    #include <sys/malloc.h>
    #include <sys/lock.h>
    #include <sys/mutex.h>
    #include <sys/proc.h>
    #include <sys/procdesc.h>
    #include <sys/jail.h>
    #include <sys/tty.h>
    #include <sys/wait.h>
    #include <sys/vmmeter.h>
    #include <sys/vnode.h>
    #include <sys/racct.h>
    #include <sys/resourcevar.h>
    #include <sys/sbuf.h>
    #include <sys/signalvar.h>
    #include <sys/sched.h>
    #include <sys/sx.h>
    #include <sys/syscallsubr.h>
    #include <sys/sysctl.h>
    #include <sys/syslog.h>
    #include <sys/ptrace.h>
    #include <sys/acct.h>           /* for acct_process() function prototype */
    #include <sys/filedesc.h>
    #include <sys/sdt.h>
    #include <sys/shm.h>
    #include <sys/sem.h>
    #include <sys/sysent.h>
    #include <sys/timers.h>
    #include <sys/umtxvar.h>
    #ifdef KTRACE
    #include <sys/ktrace.h>
    #endif
    
    #include <security/audit/audit.h>
    #include <security/mac/mac_framework.h>
    
    #include <vm/vm.h>
    #include <vm/vm_extern.h>
    #include <vm/vm_param.h>
    #include <vm/pmap.h>
    #include <vm/vm_map.h>
    #include <vm/vm_page.h>
    #include <vm/uma.h>
    
    #ifdef KDTRACE_HOOKS
    #include <sys/dtrace_bsd.h>
    dtrace_execexit_func_t  dtrace_fasttrap_exit;
    #endif
    
   SDT_PROVIDER_DECLARE(proc);
   SDT_PROBE_DEFINE1(proc, , , exit, "int");
   
   static int kern_kill_on_dbg_exit = 1;
   SYSCTL_INT(_kern, OID_AUTO, kill_on_debugger_exit, CTLFLAG_RWTUN,
       &kern_kill_on_dbg_exit, 0,
       "Kill ptraced processes when debugger exits");
   
   static bool kern_wait_dequeue_sigchld = 1;
   SYSCTL_BOOL(_kern, OID_AUTO, wait_dequeue_sigchld, CTLFLAG_RWTUN,
       &kern_wait_dequeue_sigchld, 0,
       "Dequeue SIGCHLD on wait(2) for live process");
   
   struct proc *
   proc_realparent(struct proc *child)
   {
           struct proc *p, *parent;
   
           sx_assert(&proctree_lock, SX_LOCKED);
           if ((child->p_treeflag & P_TREE_ORPHANED) == 0)
                   return (child->p_pptr->p_pid == child->p_oppid ?
                       child->p_pptr : child->p_reaper);
           for (p = child; (p->p_treeflag & P_TREE_FIRST_ORPHAN) == 0;) {
                   /* Cannot use LIST_PREV(), since the list head is not known. */
                   p = __containerof(p->p_orphan.le_prev, struct proc,
                       p_orphan.le_next);
                   KASSERT((p->p_treeflag & P_TREE_ORPHANED) != 0,
                       ("missing P_ORPHAN %p", p));
           }
           parent = __containerof(p->p_orphan.le_prev, struct proc,
               p_orphans.lh_first);
           return (parent);
   }
   
   void
   reaper_abandon_children(struct proc *p, bool exiting)
   {
           struct proc *p1, *p2, *ptmp;
   
           sx_assert(&proctree_lock, SX_XLOCKED);
           KASSERT(p != initproc, ("reaper_abandon_children for initproc"));
           if ((p->p_treeflag & P_TREE_REAPER) == 0)
                   return;
           p1 = p->p_reaper;
           LIST_FOREACH_SAFE(p2, &p->p_reaplist, p_reapsibling, ptmp) {
                   LIST_REMOVE(p2, p_reapsibling);
                   p2->p_reaper = p1;
                   p2->p_reapsubtree = p->p_reapsubtree;
                   LIST_INSERT_HEAD(&p1->p_reaplist, p2, p_reapsibling);
                   if (exiting && p2->p_pptr == p) {
                           PROC_LOCK(p2);
                           proc_reparent(p2, p1, true);
                           PROC_UNLOCK(p2);
                   }
           }
           KASSERT(LIST_EMPTY(&p->p_reaplist), ("p_reaplist not empty"));
           p->p_treeflag &= ~P_TREE_REAPER;
   }
   
   static void
   reaper_clear(struct proc *p)
   {
           struct proc *p1;
           bool clear;
   
           sx_assert(&proctree_lock, SX_LOCKED);
           LIST_REMOVE(p, p_reapsibling);
           if (p->p_reapsubtree == 1)
                   return;
           clear = true;
           LIST_FOREACH(p1, &p->p_reaper->p_reaplist, p_reapsibling) {
                   if (p1->p_reapsubtree == p->p_reapsubtree) {
                           clear = false;
                           break;
                   }
           }
           if (clear)
                   proc_id_clear(PROC_ID_REAP, p->p_reapsubtree);
   }
   
   void
   proc_clear_orphan(struct proc *p)
   {
           struct proc *p1;
   
           sx_assert(&proctree_lock, SA_XLOCKED);
           if ((p->p_treeflag & P_TREE_ORPHANED) == 0)
                   return;
           if ((p->p_treeflag & P_TREE_FIRST_ORPHAN) != 0) {
                   p1 = LIST_NEXT(p, p_orphan);
                   if (p1 != NULL)
                           p1->p_treeflag |= P_TREE_FIRST_ORPHAN;
                   p->p_treeflag &= ~P_TREE_FIRST_ORPHAN;
           }
           LIST_REMOVE(p, p_orphan);
           p->p_treeflag &= ~P_TREE_ORPHANED;
   }
   
   void
   exit_onexit(struct proc *p)
   {
           MPASS(p->p_numthreads == 1);
           umtx_thread_exit(FIRST_THREAD_IN_PROC(p));
   }
   
   /*
    * exit -- death of process.
    */
   int
   sys_exit(struct thread *td, struct exit_args *uap)
   {
   
           exit1(td, uap->rval, 0);
           __unreachable();
   }
   
   void
   proc_set_p2_wexit(struct proc *p)
   {
           PROC_LOCK_ASSERT(p, MA_OWNED);
           p->p_flag2 |= P2_WEXIT;
   }
   
   /*
    * Exit: deallocate address space and other resources, change proc state to
    * zombie, and unlink proc from allproc and parent's lists.  Save exit status
    * and rusage for wait().  Check for child processes and orphan them.
    */
   void
   exit1(struct thread *td, int rval, int signo)
   {
           struct proc *p, *nq, *q, *t;
           struct thread *tdt;
           ksiginfo_t *ksi, *ksi1;
           int signal_parent;
   
           mtx_assert(&Giant, MA_NOTOWNED);
           KASSERT(rval == 0 || signo == 0, ("exit1 rv %d sig %d", rval, signo));
           TSPROCEXIT(td->td_proc->p_pid);
   
           p = td->td_proc;
           /*
            * XXX in case we're rebooting we just let init die in order to
            * work around an unsolved stack overflow seen very late during
            * shutdown on sparc64 when the gmirror worker process exists.
            * XXX what to do now that sparc64 is gone... remove if?
            */
           if (p == initproc && rebooting == 0) {
                   printf("init died (signal %d, exit %d)\n", signo, rval);
                   panic("Going nowhere without my init!");
           }
   
           /*
            * Process deferred operations, designated with ASTF_KCLEAR.
            * For instance, we need to deref SU mp, since the thread does
            * not return to userspace, and wait for geom to stabilize.
            */
           ast_kclear(td);
   
           /*
            * MUST abort all other threads before proceeding past here.
            */
           PROC_LOCK(p);
           proc_set_p2_wexit(p);
   
           /*
            * First check if some other thread or external request got
            * here before us.  If so, act appropriately: exit or suspend.
            * We must ensure that stop requests are handled before we set
            * P_WEXIT.
            */
           thread_suspend_check(0);
           while (p->p_flag & P_HADTHREADS) {
                   /*
                    * Kill off the other threads. This requires
                    * some co-operation from other parts of the kernel
                    * so it may not be instantaneous.  With this state set
                    * any thread attempting to interruptibly
                    * sleep will return immediately with EINTR or EWOULDBLOCK
                    * which will hopefully force them to back out to userland
                    * freeing resources as they go.  Any thread attempting
                    * to return to userland will thread_exit() from ast().
                    * thread_exit() will unsuspend us when the last of the
                    * other threads exits.
                    * If there is already a thread singler after resumption,
                    * calling thread_single() will fail; in that case, we just
                    * re-check all suspension request, the thread should
                    * either be suspended there or exit.
                    */
                   if (!thread_single(p, SINGLE_EXIT))
                           /*
                            * All other activity in this process is now
                            * stopped.  Threading support has been turned
                            * off.
                            */
                           break;
                   /*
                    * Recheck for new stop or suspend requests which
                    * might appear while process lock was dropped in
                    * thread_single().
                    */
                   thread_suspend_check(0);
           }
           KASSERT(p->p_numthreads == 1,
               ("exit1: proc %p exiting with %d threads", p, p->p_numthreads));
           racct_sub(p, RACCT_NTHR, 1);
   
           /* Let event handler change exit status */
           p->p_xexit = rval;
           p->p_xsig = signo;
   
           /*
            * Ignore any pending request to stop due to a stop signal.
            * Once P_WEXIT is set, future requests will be ignored as
            * well.
            */
           p->p_flag &= ~P_STOPPED_SIG;
           KASSERT(!P_SHOULDSTOP(p), ("exiting process is stopped"));
   
           /* Note that we are exiting. */
           p->p_flag |= P_WEXIT;
   
           /*
            * Wait for any processes that have a hold on our vmspace to
            * release their reference.
            */
           while (p->p_lock > 0)
                   msleep(&p->p_lock, &p->p_mtx, PWAIT, "exithold", 0);
   
           PROC_UNLOCK(p);
           /* Drain the limit callout while we don't have the proc locked */
           callout_drain(&p->p_limco);
   
   #ifdef AUDIT
           /*
            * The Sun BSM exit token contains two components: an exit status as
            * passed to exit(), and a return value to indicate what sort of exit
            * it was.  The exit status is WEXITSTATUS(rv), but it's not clear
            * what the return value is.
            */
           AUDIT_ARG_EXIT(rval, 0);
           AUDIT_SYSCALL_EXIT(0, td);
   #endif
   
           /* Are we a task leader with peers? */
           if (p->p_peers != NULL && p == p->p_leader) {
                   mtx_lock(&ppeers_lock);
                   q = p->p_peers;
                   while (q != NULL) {
                           PROC_LOCK(q);
                           kern_psignal(q, SIGKILL);
                           PROC_UNLOCK(q);
                           q = q->p_peers;
                   }
                   while (p->p_peers != NULL)
                           msleep(p, &ppeers_lock, PWAIT, "exit1", 0);
                   mtx_unlock(&ppeers_lock);
           }
   
           itimers_exit(p);
   
           /*
            * Check if any loadable modules need anything done at process exit.
            * E.g. SYSV IPC stuff.
            * Event handler could change exit status.
            * XXX what if one of these generates an error?
            */
           EVENTHANDLER_DIRECT_INVOKE(process_exit, p);
   
           /*
            * If parent is waiting for us to exit or exec,
            * P_PPWAIT is set; we will wakeup the parent below.
            */
           PROC_LOCK(p);
           stopprofclock(p);
           p->p_ptevents = 0;
   
           /*
            * Stop the real interval timer.  If the handler is currently
            * executing, prevent it from rearming itself and let it finish.
            */
           if (timevalisset(&p->p_realtimer.it_value) &&
               callout_stop(&p->p_itcallout) == 0) {
                   timevalclear(&p->p_realtimer.it_interval);
                   PROC_UNLOCK(p);
                   callout_drain(&p->p_itcallout);
           } else {
                   PROC_UNLOCK(p);
           }
   
           if (p->p_sysent->sv_onexit != NULL)
                   p->p_sysent->sv_onexit(p);
           seltdfini(td);
   
           /*
            * Reset any sigio structures pointing to us as a result of
            * F_SETOWN with our pid.  The P_WEXIT flag interlocks with fsetown().
            */
           funsetownlst(&p->p_sigiolst);
   
           /*
            * Close open files and release open-file table.
            * This may block!
            */
           pdescfree(td);
           fdescfree(td);
   
           /*
            * Remove ourself from our leader's peer list and wake our leader.
            */
           if (p->p_leader->p_peers != NULL) {
                   mtx_lock(&ppeers_lock);
                   if (p->p_leader->p_peers != NULL) {
                           q = p->p_leader;
                           while (q->p_peers != p)
                                   q = q->p_peers;
                           q->p_peers = p->p_peers;
                           wakeup(p->p_leader);
                   }
                   mtx_unlock(&ppeers_lock);
           }
   
           exec_free_abi_mappings(p);
           vmspace_exit(td);
           (void)acct_process(td);
   
   #ifdef KTRACE
           ktrprocexit(td);
   #endif
           /*
            * Release reference to text vnode etc
            */
           if (p->p_textvp != NULL) {
                   vrele(p->p_textvp);
                   p->p_textvp = NULL;
           }
           if (p->p_textdvp != NULL) {
                   vrele(p->p_textdvp);
                   p->p_textdvp = NULL;
           }
           if (p->p_binname != NULL) {
                   free(p->p_binname, M_PARGS);
                   p->p_binname = NULL;
           }
   
           /*
            * Release our limits structure.
            */
           lim_free(p->p_limit);
           p->p_limit = NULL;
   
           tidhash_remove(td);
   
           /*
            * Call machine-dependent code to release any
            * machine-dependent resources other than the address space.
            * The address space is released by "vmspace_exitfree(p)" in
            * vm_waitproc().
            */
           cpu_exit(td);
   
           WITNESS_WARN(WARN_PANIC, NULL, "process (pid %d) exiting", p->p_pid);
   
           /*
            * Remove from allproc. It still sits in the hash.
            */
           sx_xlock(&allproc_lock);
           LIST_REMOVE(p, p_list);
   
   #ifdef DDB
           /*
            * Used by ddb's 'ps' command to find this process via the
            * pidhash.
            */
           p->p_list.le_prev = NULL;
   #endif
           prison_proc_unlink(p->p_ucred->cr_prison, p);
           sx_xunlock(&allproc_lock);
   
           sx_xlock(&proctree_lock);
           PROC_LOCK(p);
           p->p_flag &= ~(P_TRACED | P_PPWAIT | P_PPTRACE);
           PROC_UNLOCK(p);
   
           /*
            * killjobc() might drop and re-acquire proctree_lock to
            * revoke control tty if exiting process was a session leader.
            */
           killjobc();
   
           /*
            * Reparent all children processes:
            * - traced ones to the original parent (or init if we are that parent)
            * - the rest to init
            */
           q = LIST_FIRST(&p->p_children);
           if (q != NULL)          /* only need this if any child is S_ZOMB */
                   wakeup(q->p_reaper);
           for (; q != NULL; q = nq) {
                   nq = LIST_NEXT(q, p_sibling);
                   ksi = ksiginfo_alloc(M_WAITOK);
                   PROC_LOCK(q);
                   q->p_sigparent = SIGCHLD;
   
                   if ((q->p_flag & P_TRACED) == 0) {
                           proc_reparent(q, q->p_reaper, true);
                           if (q->p_state == PRS_ZOMBIE) {
                                   /*
                                    * Inform reaper about the reparented
                                    * zombie, since wait(2) has something
                                    * new to report.  Guarantee queueing
                                    * of the SIGCHLD signal, similar to
                                    * the _exit() behaviour, by providing
                                    * our ksiginfo.  Ksi is freed by the
                                    * signal delivery.
                                    */
                                   if (q->p_ksi == NULL) {
                                           ksi1 = NULL;
                                   } else {
                                           ksiginfo_copy(q->p_ksi, ksi);
                                           ksi->ksi_flags |= KSI_INS;
                                           ksi1 = ksi;
                                           ksi = NULL;
                                   }
                                   PROC_LOCK(q->p_reaper);
                                   pksignal(q->p_reaper, SIGCHLD, ksi1);
                                   PROC_UNLOCK(q->p_reaper);
                           } else if (q->p_pdeathsig > 0) {
                                   /*
                                    * The child asked to received a signal
                                    * when we exit.
                                    */
                                   kern_psignal(q, q->p_pdeathsig);
                           }
                   } else {
                           /*
                            * Traced processes are killed by default
                            * since their existence means someone is
                            * screwing up.
                            */
                           t = proc_realparent(q);
                           if (t == p) {
                                   proc_reparent(q, q->p_reaper, true);
                           } else {
                                   PROC_LOCK(t);
                                   proc_reparent(q, t, true);
                                   PROC_UNLOCK(t);
                           }
                           /*
                            * Since q was found on our children list, the
                            * proc_reparent() call moved q to the orphan
                            * list due to present P_TRACED flag. Clear
                            * orphan link for q now while q is locked.
                            */
                           proc_clear_orphan(q);
                           q->p_flag &= ~P_TRACED;
                           q->p_flag2 &= ~P2_PTRACE_FSTP;
                           q->p_ptevents = 0;
                           p->p_xthread = NULL;
                           FOREACH_THREAD_IN_PROC(q, tdt) {
                                   tdt->td_dbgflags &= ~(TDB_SUSPEND | TDB_XSIG |
                                       TDB_FSTP);
                                   tdt->td_xsig = 0;
                           }
                           if (kern_kill_on_dbg_exit) {
                                   q->p_flag &= ~P_STOPPED_TRACE;
                                   kern_psignal(q, SIGKILL);
                           } else if ((q->p_flag & (P_STOPPED_TRACE |
                               P_STOPPED_SIG)) != 0) {
                                   sigqueue_delete_proc(q, SIGTRAP);
                                   ptrace_unsuspend(q);
                           }
                   }
                   PROC_UNLOCK(q);
                   if (ksi != NULL)
                           ksiginfo_free(ksi);
           }
   
           /*
            * Also get rid of our orphans.
            */
           while ((q = LIST_FIRST(&p->p_orphans)) != NULL) {
                   PROC_LOCK(q);
                   KASSERT(q->p_oppid == p->p_pid,
                       ("orphan %p of %p has unexpected oppid %d", q, p,
                       q->p_oppid));
                   q->p_oppid = q->p_reaper->p_pid;
   
                   /*
                    * If we are the real parent of this process
                    * but it has been reparented to a debugger, then
                    * check if it asked for a signal when we exit.
                    */
                   if (q->p_pdeathsig > 0)
                           kern_psignal(q, q->p_pdeathsig);
                   CTR2(KTR_PTRACE, "exit: pid %d, clearing orphan %d", p->p_pid,
                       q->p_pid);
                   proc_clear_orphan(q);
                   PROC_UNLOCK(q);
           }
   
   #ifdef KDTRACE_HOOKS
           if (SDT_PROBES_ENABLED()) {
                   int reason = CLD_EXITED;
                   if (WCOREDUMP(signo))
                           reason = CLD_DUMPED;
                   else if (WIFSIGNALED(signo))
                           reason = CLD_KILLED;
                   SDT_PROBE1(proc, , , exit, reason);
           }
   #endif
   
           /* Save exit status. */
           PROC_LOCK(p);
           p->p_xthread = td;
   
           if (p->p_sysent->sv_ontdexit != NULL)
                   p->p_sysent->sv_ontdexit(td);
   
   #ifdef KDTRACE_HOOKS
           /*
            * Tell the DTrace fasttrap provider about the exit if it
            * has declared an interest.
            */
           if (dtrace_fasttrap_exit)
                   dtrace_fasttrap_exit(p);
   #endif
   
           /*
            * Notify interested parties of our demise.
            */
           KNOTE_LOCKED(p->p_klist, NOTE_EXIT);
   
           /*
            * If this is a process with a descriptor, we may not need to deliver
            * a signal to the parent.  proctree_lock is held over
            * procdesc_exit() to serialize concurrent calls to close() and
            * exit().
            */
           signal_parent = 0;
           if (p->p_procdesc == NULL || procdesc_exit(p)) {
                   /*
                    * Notify parent that we're gone.  If parent has the
                    * PS_NOCLDWAIT flag set, or if the handler is set to SIG_IGN,
                    * notify process 1 instead (and hope it will handle this
                    * situation).
                    */
                   PROC_LOCK(p->p_pptr);
                   mtx_lock(&p->p_pptr->p_sigacts->ps_mtx);
                   if (p->p_pptr->p_sigacts->ps_flag &
                       (PS_NOCLDWAIT | PS_CLDSIGIGN)) {
                           struct proc *pp;
   
                           mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
                           pp = p->p_pptr;
                           PROC_UNLOCK(pp);
                           proc_reparent(p, p->p_reaper, true);
                           p->p_sigparent = SIGCHLD;
                           PROC_LOCK(p->p_pptr);
   
                           /*
                            * Notify parent, so in case he was wait(2)ing or
                            * executing waitpid(2) with our pid, he will
                            * continue.
                            */
                           wakeup(pp);
                   } else
                           mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
   
                   if (p->p_pptr == p->p_reaper || p->p_pptr == initproc) {
                           signal_parent = 1;
                   } else if (p->p_sigparent != 0) {
                           if (p->p_sigparent == SIGCHLD) {
                                   signal_parent = 1;
                           } else { /* LINUX thread */
                                   signal_parent = 2;
                           }
                   }
           } else
                   PROC_LOCK(p->p_pptr);
           sx_xunlock(&proctree_lock);
   
           if (signal_parent == 1) {
                   childproc_exited(p);
           } else if (signal_parent == 2) {
                   kern_psignal(p->p_pptr, p->p_sigparent);
           }
   
           /* Tell the prison that we are gone. */
           prison_proc_free(p->p_ucred->cr_prison);
   
           /*
            * The state PRS_ZOMBIE prevents other proesses from sending
            * signal to the process, to avoid memory leak, we free memory
            * for signal queue at the time when the state is set.
            */
           sigqueue_flush(&p->p_sigqueue);
           sigqueue_flush(&td->td_sigqueue);
   
           /*
            * We have to wait until after acquiring all locks before
            * changing p_state.  We need to avoid all possible context
            * switches (including ones from blocking on a mutex) while
            * marked as a zombie.  We also have to set the zombie state
            * before we release the parent process' proc lock to avoid
            * a lost wakeup.  So, we first call wakeup, then we grab the
            * sched lock, update the state, and release the parent process'
            * proc lock.
            */
           wakeup(p->p_pptr);
           cv_broadcast(&p->p_pwait);
           sched_exit(p->p_pptr, td);
           PROC_SLOCK(p);
           p->p_state = PRS_ZOMBIE;
           PROC_UNLOCK(p->p_pptr);
   
           /*
            * Save our children's rusage information in our exit rusage.
            */
           PROC_STATLOCK(p);
           ruadd(&p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux);
           PROC_STATUNLOCK(p);
   
           /*
            * Make sure the scheduler takes this thread out of its tables etc.
            * This will also release this thread's reference to the ucred.
            * Other thread parts to release include pcb bits and such.
            */
           thread_exit();
   }
   
   #ifndef _SYS_SYSPROTO_H_
   struct abort2_args {
           char *why;
           int nargs;
           void **args;
   };
   #endif
   
   int
   sys_abort2(struct thread *td, struct abort2_args *uap)
   {
           void *uargs[16];
           void **uargsp;
           int error, nargs;
   
           nargs = uap->nargs;
           if (nargs < 0 || nargs > nitems(uargs))
                   nargs = -1;
           uargsp = NULL;
           if (nargs > 0) {
                   if (uap->args != NULL) {
                           error = copyin(uap->args, uargs,
                               nargs * sizeof(void *));
                           if (error != 0)
                                   nargs = -1;
                           else
                                   uargsp = uargs;
                   } else
                           nargs = -1;
           }
           return (kern_abort2(td, uap->why, nargs, uargsp));
   }
   
   /*
    * kern_abort2()
    * Arguments:
    *  why - user pointer to why
    *  nargs - number of arguments copied or -1 if an error occurred in copying
    *  args - pointer to an array of pointers in kernel format
    */
   int
   kern_abort2(struct thread *td, const char *why, int nargs, void **uargs)
   {
           struct proc *p = td->td_proc;
           struct sbuf *sb;
           int error, i, sig;
   
           /*
            * Do it right now so we can log either proper call of abort2(), or
            * note, that invalid argument was passed. 512 is big enough to
            * handle 16 arguments' descriptions with additional comments.
            */
           sb = sbuf_new(NULL, NULL, 512, SBUF_FIXEDLEN);
           sbuf_clear(sb);
           sbuf_printf(sb, "%s(pid %d uid %d) aborted: ",
               p->p_comm, p->p_pid, td->td_ucred->cr_uid);
           /*
            * Since we can't return from abort2(), send SIGKILL in cases, where
            * abort2() was called improperly
            */
           sig = SIGKILL;
           /* Prevent from DoSes from user-space. */
           if (nargs == -1)
                   goto out;
           KASSERT(nargs >= 0 && nargs <= 16, ("called with too many args (%d)",
               nargs));
           /*
            * Limit size of 'reason' string to 128. Will fit even when
            * maximal number of arguments was chosen to be logged.
            */
           if (why != NULL) {
                   error = sbuf_copyin(sb, why, 128);
                   if (error < 0)
                           goto out;
           } else {
                   sbuf_printf(sb, "(null)");
           }
           if (nargs > 0) {
                   sbuf_printf(sb, "(");
                   for (i = 0;i < nargs; i++)
                           sbuf_printf(sb, "%s%p", i == 0 ? "" : ", ", uargs[i]);
                   sbuf_printf(sb, ")");
           }
           /*
            * Final stage: arguments were proper, string has been
            * successfully copied from userspace, and copying pointers
            * from user-space succeed.
            */
           sig = SIGABRT;
   out:
           if (sig == SIGKILL) {
                   sbuf_trim(sb);
                   sbuf_printf(sb, " (Reason text inaccessible)");
           }
           sbuf_cat(sb, "\n");
           sbuf_finish(sb);
           log(LOG_INFO, "%s", sbuf_data(sb));
           sbuf_delete(sb);
           exit1(td, 0, sig);
           return (0);
   }
   
   #ifdef COMPAT_43
   /*
    * The dirty work is handled by kern_wait().
    */
   int
   owait(struct thread *td, struct owait_args *uap __unused)
   {
           int error, status;
   
           error = kern_wait(td, WAIT_ANY, &status, 0, NULL);
           if (error == 0)
                   td->td_retval[1] = status;
           return (error);
   }
   #endif /* COMPAT_43 */
   
   /*
    * The dirty work is handled by kern_wait().
    */
   int
   sys_wait4(struct thread *td, struct wait4_args *uap)
   {
           struct rusage ru, *rup;
           int error, status;
   
           if (uap->rusage != NULL)
                   rup = &ru;
           else
                   rup = NULL;
           error = kern_wait(td, uap->pid, &status, uap->options, rup);
           if (uap->status != NULL && error == 0 && td->td_retval[0] != 0)
                   error = copyout(&status, uap->status, sizeof(status));
           if (uap->rusage != NULL && error == 0 && td->td_retval[0] != 0)
                   error = copyout(&ru, uap->rusage, sizeof(struct rusage));
           return (error);
   }
   
   int
   sys_wait6(struct thread *td, struct wait6_args *uap)
   {
           struct __wrusage wru, *wrup;
           siginfo_t si, *sip;
           idtype_t idtype;
           id_t id;
           int error, status;
   
           idtype = uap->idtype;
           id = uap->id;
   
           if (uap->wrusage != NULL)
                   wrup = &wru;
           else
                   wrup = NULL;
   
           if (uap->info != NULL) {
                   sip = &si;
                   bzero(sip, sizeof(*sip));
           } else
                   sip = NULL;
   
           /*
            *  We expect all callers of wait6() to know about WEXITED and
            *  WTRAPPED.
            */
           error = kern_wait6(td, idtype, id, &status, uap->options, wrup, sip);
   
           if (uap->status != NULL && error == 0 && td->td_retval[0] != 0)
                   error = copyout(&status, uap->status, sizeof(status));
           if (uap->wrusage != NULL && error == 0 && td->td_retval[0] != 0)
                   error = copyout(&wru, uap->wrusage, sizeof(wru));
           if (uap->info != NULL && error == 0)
                   error = copyout(&si, uap->info, sizeof(si));
           return (error);
   }
   
   /*
    * Reap the remains of a zombie process and optionally return status and
    * rusage.  Asserts and will release both the proctree_lock and the process
    * lock as part of its work.
    */
   void
   proc_reap(struct thread *td, struct proc *p, int *status, int options)
   {
           struct proc *q, *t;
   
           sx_assert(&proctree_lock, SA_XLOCKED);
           PROC_LOCK_ASSERT(p, MA_OWNED);
           KASSERT(p->p_state == PRS_ZOMBIE, ("proc_reap: !PRS_ZOMBIE"));
   
           mtx_spin_wait_unlocked(&p->p_slock);
   
           q = td->td_proc;
   
           if (status)
                   *status = KW_EXITCODE(p->p_xexit, p->p_xsig);
           if (options & WNOWAIT) {
                   /*
                    *  Only poll, returning the status.  Caller does not wish to
                    * release the proc struct just yet.
                    */
                   PROC_UNLOCK(p);
                   sx_xunlock(&proctree_lock);
                   return;
           }
   
           PROC_LOCK(q);
           sigqueue_take(p->p_ksi);
           PROC_UNLOCK(q);
   
           /*
            * If we got the child via a ptrace 'attach', we need to give it back
            * to the old parent.
            */
           if (p->p_oppid != p->p_pptr->p_pid) {
                   PROC_UNLOCK(p);
                   t = proc_realparent(p);
                   PROC_LOCK(t);
                   PROC_LOCK(p);
                   CTR2(KTR_PTRACE,
                       "wait: traced child %d moved back to parent %d", p->p_pid,
                       t->p_pid);
                   proc_reparent(p, t, false);
                   PROC_UNLOCK(p);
                   pksignal(t, SIGCHLD, p->p_ksi);
                   wakeup(t);
                   cv_broadcast(&p->p_pwait);
                   PROC_UNLOCK(t);
                   sx_xunlock(&proctree_lock);
                   return;
           }
           PROC_UNLOCK(p);
   
           /*
            * Remove other references to this process to ensure we have an
            * exclusive reference.
            */
           sx_xlock(PIDHASHLOCK(p->p_pid));
           LIST_REMOVE(p, p_hash);
           sx_xunlock(PIDHASHLOCK(p->p_pid));
           LIST_REMOVE(p, p_sibling);
           reaper_abandon_children(p, true);
           reaper_clear(p);
           PROC_LOCK(p);
           proc_clear_orphan(p);
           PROC_UNLOCK(p);
           leavepgrp(p);
           if (p->p_procdesc != NULL)
                   procdesc_reap(p);
           sx_xunlock(&proctree_lock);
   
           proc_id_clear(PROC_ID_PID, p->p_pid);
   
           PROC_LOCK(p);
           knlist_detach(p->p_klist);
           p->p_klist = NULL;
           PROC_UNLOCK(p);
   
           /*
            * Removal from allproc list and process group list paired with
            * PROC_LOCK which was executed during that time should guarantee
            * nothing can reach this process anymore. As such further locking
            * is unnecessary.
            */
           p->p_xexit = p->p_xsig = 0;             /* XXX: why? */
   
           PROC_LOCK(q);
           ruadd(&q->p_stats->p_cru, &q->p_crux, &p->p_ru, &p->p_rux);
          PROC_UNLOCK(q);
  
          /*
           * Decrement the count of procs running with this uid.
           */
          (void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
  
          /*
           * Destroy resource accounting information associated with the process.
           */
  #ifdef RACCT
          if (racct_enable) {
                  PROC_LOCK(p);
                  racct_sub(p, RACCT_NPROC, 1);
                  PROC_UNLOCK(p);
          }
  #endif
          racct_proc_exit(p);
  
          /*
           * Free credentials, arguments, and sigacts.
           */
          proc_unset_cred(p);
          pargs_drop(p->p_args);
          p->p_args = NULL;
          sigacts_free(p->p_sigacts);
          p->p_sigacts = NULL;
  
          /*
           * Do any thread-system specific cleanups.
           */
          thread_wait(p);
  
          /*
           * Give vm and machine-dependent layer a chance to free anything that
           * cpu_exit couldn't release while still running in process context.
           */
          vm_waitproc(p);
  #ifdef MAC
          mac_proc_destroy(p);
  #endif
  
          KASSERT(FIRST_THREAD_IN_PROC(p),
              ("proc_reap: no residual thread!"));
          uma_zfree(proc_zone, p);
          atomic_add_int(&nprocs, -1);
  }
  
  static int
  proc_to_reap(struct thread *td, struct proc *p, idtype_t idtype, id_t id,
      int *status, int options, struct __wrusage *wrusage, siginfo_t *siginfo,
      int check_only)
  {
          struct rusage *rup;
  
          sx_assert(&proctree_lock, SA_XLOCKED);
  
          PROC_LOCK(p);
  
          switch (idtype) {
          case P_ALL:
                  if (p->p_procdesc == NULL ||
                     (p->p_pptr == td->td_proc &&
                     (p->p_flag & P_TRACED) != 0)) {
                          break;
                  }
  
                  PROC_UNLOCK(p);
                  return (0);
          case P_PID:
                  if (p->p_pid != (pid_t)id) {
                          PROC_UNLOCK(p);
                          return (0);
                  }
                  break;
          case P_PGID:
                  if (p->p_pgid != (pid_t)id) {
                          PROC_UNLOCK(p);
                          return (0);
                  }
                  break;
          case P_SID:
                  if (p->p_session->s_sid != (pid_t)id) {
                          PROC_UNLOCK(p);
                          return (0);
                  }
                  break;
          case P_UID:
                  if (p->p_ucred->cr_uid != (uid_t)id) {
                          PROC_UNLOCK(p);
                          return (0);
                  }
                  break;
          case P_GID:
                  if (p->p_ucred->cr_gid != (gid_t)id) {
                          PROC_UNLOCK(p);
                          return (0);
                  }
                  break;
          case P_JAILID:
                  if (p->p_ucred->cr_prison->pr_id != (int)id) {
                          PROC_UNLOCK(p);
                          return (0);
                  }
                  break;
          /*
           * It seems that the thread structures get zeroed out
           * at process exit.  This makes it impossible to
           * support P_SETID, P_CID or P_CPUID.
           */
          default:
                  PROC_UNLOCK(p);
                  return (0);
          }
  
          if (p_canwait(td, p)) {
                  PROC_UNLOCK(p);
                  return (0);
          }
  
          if (((options & WEXITED) == 0) && (p->p_state == PRS_ZOMBIE)) {
                  PROC_UNLOCK(p);
                  return (0);
          }
  
          /*
           * This special case handles a kthread spawned by linux_clone
           * (see linux_misc.c).  The linux_wait4 and linux_waitpid
           * functions need to be able to distinguish between waiting
           * on a process and waiting on a thread.  It is a thread if
           * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
           * signifies we want to wait for threads and not processes.
           */
          if ((p->p_sigparent != SIGCHLD) ^
              ((options & WLINUXCLONE) != 0)) {
                  PROC_UNLOCK(p);
                  return (0);
          }
  
          if (siginfo != NULL) {
                  bzero(siginfo, sizeof(*siginfo));
                  siginfo->si_errno = 0;
  
                  /*
                   * SUSv4 requires that the si_signo value is always
                   * SIGCHLD. Obey it despite the rfork(2) interface
                   * allows to request other signal for child exit
                   * notification.
                   */
                  siginfo->si_signo = SIGCHLD;
  
                  /*
                   *  This is still a rough estimate.  We will fix the
                   *  cases TRAPPED, STOPPED, and CONTINUED later.
                   */
                  if (WCOREDUMP(p->p_xsig)) {
                          siginfo->si_code = CLD_DUMPED;
                          siginfo->si_status = WTERMSIG(p->p_xsig);
                  } else if (WIFSIGNALED(p->p_xsig)) {
                          siginfo->si_code = CLD_KILLED;
                          siginfo->si_status = WTERMSIG(p->p_xsig);
                  } else {
                          siginfo->si_code = CLD_EXITED;
                          siginfo->si_status = p->p_xexit;
                  }
  
                  siginfo->si_pid = p->p_pid;
                  siginfo->si_uid = p->p_ucred->cr_uid;
  
                  /*
                   * The si_addr field would be useful additional
                   * detail, but apparently the PC value may be lost
                   * when we reach this point.  bzero() above sets
                   * siginfo->si_addr to NULL.
                   */
          }
  
          /*
           * There should be no reason to limit resources usage info to
           * exited processes only.  A snapshot about any resources used
           * by a stopped process may be exactly what is needed.
           */
          if (wrusage != NULL) {
                  rup = &wrusage->wru_self;
                  *rup = p->p_ru;
                  PROC_STATLOCK(p);
                  calcru(p, &rup->ru_utime, &rup->ru_stime);
                  PROC_STATUNLOCK(p);
  
                  rup = &wrusage->wru_children;
                  *rup = p->p_stats->p_cru;
                  calccru(p, &rup->ru_utime, &rup->ru_stime);
          }
  
          if (p->p_state == PRS_ZOMBIE && !check_only) {
                  proc_reap(td, p, status, options);
                  return (-1);
          }
          return (1);
  }
  
  int
  kern_wait(struct thread *td, pid_t pid, int *status, int options,
      struct rusage *rusage)
  {
          struct __wrusage wru, *wrup;
          idtype_t idtype;
          id_t id;
          int ret;
  
          /*
           * Translate the special pid values into the (idtype, pid)
           * pair for kern_wait6.  The WAIT_MYPGRP case is handled by
           * kern_wait6() on its own.
           */
          if (pid == WAIT_ANY) {
                  idtype = P_ALL;
                  id = 0;
          } else if (pid < 0) {
                  idtype = P_PGID;
                  id = (id_t)-pid;
          } else {
                  idtype = P_PID;
                  id = (id_t)pid;
          }
  
          if (rusage != NULL)
                  wrup = &wru;
          else
                  wrup = NULL;
  
          /*
           * For backward compatibility we implicitly add flags WEXITED
           * and WTRAPPED here.
           */
          options |= WEXITED | WTRAPPED;
          ret = kern_wait6(td, idtype, id, status, options, wrup, NULL);
          if (rusage != NULL)
                  *rusage = wru.wru_self;
          return (ret);
  }
  
  static void
  report_alive_proc(struct thread *td, struct proc *p, siginfo_t *siginfo,
      int *status, int options, int si_code)
  {
          bool cont;
  
          PROC_LOCK_ASSERT(p, MA_OWNED);
          sx_assert(&proctree_lock, SA_XLOCKED);
          MPASS(si_code == CLD_TRAPPED || si_code == CLD_STOPPED ||
              si_code == CLD_CONTINUED);
  
          cont = si_code == CLD_CONTINUED;
          if ((options & WNOWAIT) == 0) {
                  if (cont)
                          p->p_flag &= ~P_CONTINUED;
                  else
                          p->p_flag |= P_WAITED;
                  if (kern_wait_dequeue_sigchld &&
                      (td->td_proc->p_sysent->sv_flags & SV_SIG_WAITNDQ) == 0) {
                          PROC_LOCK(td->td_proc);
                          sigqueue_take(p->p_ksi);
                          PROC_UNLOCK(td->td_proc);
                  }
          }
          sx_xunlock(&proctree_lock);
          if (siginfo != NULL) {
                  siginfo->si_code = si_code;
                  siginfo->si_status = cont ? SIGCONT : p->p_xsig;
          }
          if (status != NULL)
                  *status = cont ? SIGCONT : W_STOPCODE(p->p_xsig);
          td->td_retval[0] = p->p_pid;
          PROC_UNLOCK(p);
  }
  
  int
  kern_wait6(struct thread *td, idtype_t idtype, id_t id, int *status,
      int options, struct __wrusage *wrusage, siginfo_t *siginfo)
  {
          struct proc *p, *q;
          pid_t pid;
          int error, nfound, ret;
          bool report;
  
          AUDIT_ARG_VALUE((int)idtype);   /* XXX - This is likely wrong! */
          AUDIT_ARG_PID((pid_t)id);       /* XXX - This may be wrong! */
          AUDIT_ARG_VALUE(options);
  
          q = td->td_proc;
  
          if ((pid_t)id == WAIT_MYPGRP && (idtype == P_PID || idtype == P_PGID)) {
                  PROC_LOCK(q);
                  id = (id_t)q->p_pgid;
                  PROC_UNLOCK(q);
                  idtype = P_PGID;
          }
  
          /* If we don't know the option, just return. */
          if ((options & ~(WUNTRACED | WNOHANG | WCONTINUED | WNOWAIT |
              WEXITED | WTRAPPED | WLINUXCLONE)) != 0)
                  return (EINVAL);
          if ((options & (WEXITED | WUNTRACED | WCONTINUED | WTRAPPED)) == 0) {
                  /*
                   * We will be unable to find any matching processes,
                   * because there are no known events to look for.
                   * Prefer to return error instead of blocking
                   * indefinitely.
                   */
                  return (EINVAL);
          }
  
  loop:
          if (q->p_flag & P_STATCHILD) {
                  PROC_LOCK(q);
                  q->p_flag &= ~P_STATCHILD;
                  PROC_UNLOCK(q);
          }
          sx_xlock(&proctree_lock);
  loop_locked:
          nfound = 0;
          LIST_FOREACH(p, &q->p_children, p_sibling) {
                  pid = p->p_pid;
                  ret = proc_to_reap(td, p, idtype, id, status, options,
                      wrusage, siginfo, 0);
                  if (ret == 0)
                          continue;
                  else if (ret != 1) {
                          td->td_retval[0] = pid;
                          return (0);
                  }
  
                  nfound++;
                  PROC_LOCK_ASSERT(p, MA_OWNED);
  
                  if ((options & WTRAPPED) != 0 &&
                      (p->p_flag & P_TRACED) != 0) {
                          PROC_SLOCK(p);
                          report =
                              ((p->p_flag & (P_STOPPED_TRACE | P_STOPPED_SIG)) &&
                              p->p_suspcount == p->p_numthreads &&
                              (p->p_flag & P_WAITED) == 0);
                          PROC_SUNLOCK(p);
                          if (report) {
                          CTR4(KTR_PTRACE,
                              "wait: returning trapped pid %d status %#x "
                              "(xstat %d) xthread %d",
                              p->p_pid, W_STOPCODE(p->p_xsig), p->p_xsig,
                              p->p_xthread != NULL ?
                              p->p_xthread->td_tid : -1);
                                  report_alive_proc(td, p, siginfo, status,
                                      options, CLD_TRAPPED);
                                  return (0);
                          }
                  }
                  if ((options & WUNTRACED) != 0 &&
                      (p->p_flag & P_STOPPED_SIG) != 0) {
                          PROC_SLOCK(p);
                          report = (p->p_suspcount == p->p_numthreads &&
                              ((p->p_flag & P_WAITED) == 0));
                          PROC_SUNLOCK(p);
                          if (report) {
                                  report_alive_proc(td, p, siginfo, status,
                                      options, CLD_STOPPED);
                                  return (0);
                          }
                  }
                  if ((options & WCONTINUED) != 0 &&
                      (p->p_flag & P_CONTINUED) != 0) {
                          report_alive_proc(td, p, siginfo, status, options,
                              CLD_CONTINUED);
                          return (0);
                  }
                  PROC_UNLOCK(p);
          }
  
          /*
           * Look in the orphans list too, to allow the parent to
           * collect it's child exit status even if child is being
           * debugged.
           *
           * Debugger detaches from the parent upon successful
           * switch-over from parent to child.  At this point due to
           * re-parenting the parent loses the child to debugger and a
           * wait4(2) call would report that it has no children to wait
           * for.  By maintaining a list of orphans we allow the parent
           * to successfully wait until the child becomes a zombie.
           */
          if (nfound == 0) {
                  LIST_FOREACH(p, &q->p_orphans, p_orphan) {
                          ret = proc_to_reap(td, p, idtype, id, NULL, options,
                              NULL, NULL, 1);
                          if (ret != 0) {
                                  KASSERT(ret != -1, ("reaped an orphan (pid %d)",
                                      (int)td->td_retval[0]));
                                  PROC_UNLOCK(p);
                                  nfound++;
                                  break;
                          }
                  }
          }
          if (nfound == 0) {
                  sx_xunlock(&proctree_lock);
                  return (ECHILD);
          }
          if (options & WNOHANG) {
                  sx_xunlock(&proctree_lock);
                  td->td_retval[0] = 0;
                  return (0);
          }
          PROC_LOCK(q);
          if (q->p_flag & P_STATCHILD) {
                  q->p_flag &= ~P_STATCHILD;
                  PROC_UNLOCK(q);
                  goto loop_locked;
          }
          sx_xunlock(&proctree_lock);
          error = msleep(q, &q->p_mtx, PWAIT | PCATCH | PDROP, "wait", 0);
          if (error)
                  return (error);
          goto loop;
  }
  
  void
  proc_add_orphan(struct proc *child, struct proc *parent)
  {
  
          sx_assert(&proctree_lock, SX_XLOCKED);
          KASSERT((child->p_flag & P_TRACED) != 0,
              ("proc_add_orphan: not traced"));
  
          if (LIST_EMPTY(&parent->p_orphans)) {
                  child->p_treeflag |= P_TREE_FIRST_ORPHAN;
                  LIST_INSERT_HEAD(&parent->p_orphans, child, p_orphan);
          } else {
                  LIST_INSERT_AFTER(LIST_FIRST(&parent->p_orphans),
                      child, p_orphan);
          }
          child->p_treeflag |= P_TREE_ORPHANED;
  }
  
  /*
   * Make process 'parent' the new parent of process 'child'.
   * Must be called with an exclusive hold of proctree lock.
   */
  void
  proc_reparent(struct proc *child, struct proc *parent, bool set_oppid)
  {
  
          sx_assert(&proctree_lock, SX_XLOCKED);
          PROC_LOCK_ASSERT(child, MA_OWNED);
          if (child->p_pptr == parent)
                  return;
  
          PROC_LOCK(child->p_pptr);
          sigqueue_take(child->p_ksi);
          PROC_UNLOCK(child->p_pptr);
          LIST_REMOVE(child, p_sibling);
          LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
  
          proc_clear_orphan(child);
          if ((child->p_flag & P_TRACED) != 0) {
                  proc_add_orphan(child, child->p_pptr);
          }
  
          child->p_pptr = parent;
          if (set_oppid)
                  child->p_oppid = parent->p_pid;
  }

Cache object: 4c958ecbde35b654cd791e0f8d74026c