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NetBSD/sys/kern/kern_exit.c

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/* $NetBSD: kern_exit.c,v 1.180 2007/05/31 06:24:23 rmind Exp $ */
/*-
* Copyright (c) 1998, 1999, 2006, 2007 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
* NASA Ames Research Center, and by Andrew Doran.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*
* 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 8.10 (Berkeley) 2/23/95
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_exit.c,v 1.180 2007/05/31 06:24:23 rmind Exp $");
#include "opt_ktrace.h"
#include "opt_perfctrs.h"
#include "opt_systrace.h"
#include "opt_sysv.h"
#include <sys/param.h>
#include <sys/aio.h>
#include <sys/systm.h>
#include <sys/ioctl.h>
#include <sys/tty.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/buf.h>
#include <sys/wait.h>
#include <sys/file.h>
#include <sys/vnode.h>
#include <sys/syslog.h>
#include <sys/malloc.h>
#include <sys/pool.h>
#include <sys/resourcevar.h>
#if defined(PERFCTRS)
#include <sys/pmc.h>
#endif
#include <sys/ptrace.h>
#include <sys/acct.h>
#include <sys/filedesc.h>
#include <sys/ras.h>
#include <sys/signalvar.h>
#include <sys/sched.h>
#include <sys/mount.h>
#include <sys/syscallargs.h>
#include <sys/systrace.h>
#include <sys/kauth.h>
#include <sys/sleepq.h>
#include <sys/lockdebug.h>
#include <sys/ktrace.h>
#include <machine/cpu.h>
#include <uvm/uvm_extern.h>
#define DEBUG_EXIT
#ifdef DEBUG_EXIT
int debug_exit = 0;
#define DPRINTF(x) if (debug_exit) printf x
#else
#define DPRINTF(x)
#endif
static int find_stopped_child(struct proc *, pid_t, int, struct proc **, int *);
static void proc_free(struct proc *, struct rusage *);
/*
* Fill in the appropriate signal information, and signal the parent.
*/
static void
exit_psignal(struct proc *p, struct proc *pp, ksiginfo_t *ksi)
{
KSI_INIT(ksi);
if ((ksi->ksi_signo = P_EXITSIG(p)) == SIGCHLD) {
if (WIFSIGNALED(p->p_xstat)) {
if (WCOREDUMP(p->p_xstat))
ksi->ksi_code = CLD_DUMPED;
else
ksi->ksi_code = CLD_KILLED;
} else {
ksi->ksi_code = CLD_EXITED;
}
}
/*
* We fill those in, even for non-SIGCHLD.
* It's safe to access p->p_cred unlocked here.
*/
ksi->ksi_pid = p->p_pid;
ksi->ksi_uid = kauth_cred_geteuid(p->p_cred);
ksi->ksi_status = p->p_xstat;
/* XXX: is this still valid? */
ksi->ksi_utime = p->p_stats->p_ru.ru_utime.tv_sec;
ksi->ksi_stime = p->p_stats->p_ru.ru_stime.tv_sec;
}
/*
* exit --
* Death of process.
*/
int
sys_exit(struct lwp *l, void *v, register_t *retval)
{
struct sys_exit_args /* {
syscallarg(int) rval;
} */ *uap = v;
struct proc *p = l->l_proc;
/* Don't call exit1() multiple times in the same process. */
mutex_enter(&p->p_smutex);
if (p->p_sflag & PS_WEXIT) {
mutex_exit(&p->p_smutex);
lwp_exit(l);
}
/* exit1() will release the mutex. */
exit1(l, W_EXITCODE(SCARG(uap, rval), 0));
/* NOTREACHED */
return (0);
}
/*
* 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.
*
* Must be called with p->p_smutex held. Does not return.
*/
void
exit1(struct lwp *l, int rv)
{
struct proc *p, *q, *nq;
int s;
ksiginfo_t ksi;
ksiginfoq_t kq;
int wakeinit;
p = l->l_proc;
KASSERT(mutex_owned(&p->p_smutex));
if (__predict_false(p == initproc))
panic("init died (signal %d, exit %d)",
WTERMSIG(rv), WEXITSTATUS(rv));
p->p_sflag |= PS_WEXIT;
/*
* Force all other LWPs to exit before we do. Only then can we
* begin to tear down the rest of the process state.
*/
if (p->p_nlwps > 1)
exit_lwps(l);
ksiginfo_queue_init(&kq);
/*
* If we have been asked to stop on exit, do so now.
*/
if (p->p_sflag & PS_STOPEXIT) {
KERNEL_UNLOCK_ALL(l, &l->l_biglocks);
sigclearall(p, &contsigmask, &kq);
p->p_waited = 0;
mb_write();
p->p_stat = SSTOP;
lwp_lock(l);
p->p_nrlwps--;
l->l_stat = LSSTOP;
mutex_exit(&p->p_smutex);
mi_switch(l);
KERNEL_LOCK(l->l_biglocks, l);
} else
mutex_exit(&p->p_smutex);
/* Destroy all AIO works */
aio_exit(p, p->p_aio);
/*
* Drain all remaining references that procfs, ptrace and others may
* have on the process.
*/
mutex_enter(&p->p_mutex);
proc_drainrefs(p);
mutex_exit(&p->p_mutex);
/*
* Bin any remaining signals and mark the process as dying so it will
* not be found for, e.g. signals.
*/
mutex_enter(&p->p_smutex);
sigfillset(&p->p_sigctx.ps_sigignore);
sigclearall(p, NULL, &kq);
p->p_stat = SDYING;
mutex_exit(&p->p_smutex);
ksiginfo_queue_drain(&kq);
DPRINTF(("exit1: %d.%d exiting.\n", p->p_pid, l->l_lid));
#ifdef PGINPROF
vmsizmon();
#endif
timers_free(p, TIMERS_ALL);
#if defined(__HAVE_RAS)
ras_purgeall(p);
#endif
/*
* Close open files, release open-file table and free signal
* actions. This may block!
*/
fdfree(l);
cwdfree(p->p_cwdi);
p->p_cwdi = NULL;
doexithooks(p);
sigactsfree(p->p_sigacts);
/*
* Write out accounting data.
*/
(void)acct_process(l);
#ifdef KTRACE
/*
* Release trace file.
*/
if (p->p_tracep != NULL) {
mutex_enter(&ktrace_mutex);
ktrderef(p);
mutex_exit(&ktrace_mutex);
}
#endif
#ifdef SYSTRACE
systrace_sys_exit(p);
#endif
/*
* If emulation has process exit hook, call it now.
* Set the exit status now so that the exit hook has
* an opportunity to tweak it (COMPAT_LINUX requires
* this for thread group emulation)
*/
p->p_xstat = rv;
if (p->p_emul->e_proc_exit)
(*p->p_emul->e_proc_exit)(p);
/* Collect child u-areas. */
uvm_uarea_drain(false);
/*
* Free the VM resources we're still holding on to.
* We must do this from a valid thread because doing
* so may block. This frees vmspace, which we don't
* need anymore. The only remaining lwp is the one
* we run at this moment, nothing runs in userland
* anymore.
*/
uvm_proc_exit(p);
/*
* Stop profiling.
*/
if ((p->p_stflag & PST_PROFIL) != 0) {
mutex_spin_enter(&p->p_stmutex);
stopprofclock(p);
mutex_spin_exit(&p->p_stmutex);
}
/*
* If parent is waiting for us to exit or exec, P_PPWAIT is set; we
* wake up the parent early to avoid deadlock. We can do this once
* the VM resources are released.
*/
mutex_enter(&proclist_lock);
mutex_enter(&p->p_smutex);
if (p->p_sflag & PS_PPWAIT) {
p->p_sflag &= ~PS_PPWAIT;
cv_signal(&p->p_pptr->p_waitcv);
}
mutex_exit(&p->p_smutex);
if (SESS_LEADER(p)) {
struct vnode *vprele = NULL, *vprevoke = NULL;
struct session *sp = p->p_session;
struct tty *tp;
if (sp->s_ttyvp) {
/*
* Controlling process.
* Signal foreground pgrp,
* drain controlling terminal
* and revoke access to controlling terminal.
*/
tp = sp->s_ttyp;
s = spltty();
TTY_LOCK(tp);
if (tp->t_session == sp) {
if (tp->t_pgrp) {
mutex_enter(&proclist_mutex);
pgsignal(tp->t_pgrp, SIGHUP, 1);
mutex_exit(&proclist_mutex);
}
/* we can't guarantee the revoke will do this */
tp->t_pgrp = NULL;
tp->t_session = NULL;
TTY_UNLOCK(tp);
splx(s);
SESSRELE(sp);
mutex_exit(&proclist_lock);
(void) ttywait(tp);
mutex_enter(&proclist_lock);
/*
* The tty could have been revoked
* if we blocked.
*/
vprevoke = sp->s_ttyvp;
} else {
TTY_UNLOCK(tp);
splx(s);
}
vprele = sp->s_ttyvp;
sp->s_ttyvp = NULL;
/*
* s_ttyp is not zero'd; we use this to indicate
* that the session once had a controlling terminal.
* (for logging and informational purposes)
*/
}
sp->s_leader = NULL;
if (vprevoke != NULL || vprele != NULL) {
mutex_exit(&proclist_lock);
if (vprevoke != NULL)
VOP_REVOKE(vprevoke, REVOKEALL);
if (vprele != NULL)
vrele(vprele);
mutex_enter(&proclist_lock);
}
}
mutex_enter(&proclist_mutex);
fixjobc(p, p->p_pgrp, 0);
mutex_exit(&proclist_mutex);
/*
* Finalize the last LWP's specificdata, as well as the
* specificdata for the proc itself.
*/
lwp_finispecific(l);
proc_finispecific(p);
/*
* Notify interested parties of our demise.
*/
KNOTE(&p->p_klist, NOTE_EXIT);
#if PERFCTRS
/*
* Save final PMC information in parent process & clean up.
*/
if (PMC_ENABLED(p)) {
pmc_save_context(p);
pmc_accumulate(p->p_pptr, p);
pmc_process_exit(p);
}
#endif
/*
* Reset p_opptr pointer of all former children which got
* traced by another process and were reparented. We reset
* it to NULL here; the trace detach code then reparents
* the child to initproc. We only check allproc list, since
* eventual former children on zombproc list won't reference
* p_opptr anymore.
*/
if (p->p_slflag & PSL_CHTRACED) {
PROCLIST_FOREACH(q, &allproc) {
if (q->p_opptr == p)
q->p_opptr = NULL;
}
}
/*
* Give orphaned children to init(8).
*/
q = LIST_FIRST(&p->p_children);
wakeinit = (q != NULL);
for (; q != NULL; q = nq) {
nq = LIST_NEXT(q, p_sibling);
/*
* Traced processes are killed since their existence
* means someone is screwing up. Since we reset the
* trace flags, the logic in sys_wait4() would not be
* triggered to reparent the process to its
* original parent, so we must do this here.
*/
if (q->p_slflag & PSL_TRACED) {
mutex_enter(&p->p_smutex);
q->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL);
mutex_exit(&p->p_smutex);
if (q->p_opptr != q->p_pptr) {
struct proc *t = q->p_opptr;
proc_reparent(q, t ? t : initproc);
q->p_opptr = NULL;
} else
proc_reparent(q, initproc);
killproc(q, "orphaned traced process");
} else
proc_reparent(q, initproc);
}
/*
* Move proc from allproc to zombproc, it's now nearly ready to be
* collected by parent.
*/
mutex_enter(&proclist_mutex);
LIST_REMOVE(l, l_list);
LIST_REMOVE(p, p_list);
LIST_INSERT_HEAD(&zombproc, p, p_list);
/*
* Mark the process as dead. We must do this before we signal
* the parent.
*/
p->p_stat = SDEAD;
/* Put in front of parent's sibling list for parent to collect it */
q = p->p_pptr;
q->p_nstopchild++;
if (LIST_FIRST(&q->p_children) != p) {
/* Put child where it can be found quickly */
LIST_REMOVE(p, p_sibling);
LIST_INSERT_HEAD(&q->p_children, p, p_sibling);
}
mutex_exit(&proclist_mutex);
/*
* Notify parent that we're gone. If parent has the P_NOCLDWAIT
* flag set, notify init instead (and hope it will handle
* this situation).
*/
mutex_enter(&q->p_mutex);
if (q->p_flag & (PK_NOCLDWAIT|PK_CLDSIGIGN)) {
proc_reparent(p, initproc);
wakeinit = 1;
/*
* If this was the last child of our parent, notify
* parent, so in case he was wait(2)ing, he will
* continue.
*/
if (LIST_FIRST(&q->p_children) == NULL)
cv_signal(&q->p_waitcv);
}
mutex_exit(&q->p_mutex);
/* Reload parent pointer, since p may have been reparented above */
q = p->p_pptr;
if ((p->p_slflag & PSL_FSTRACE) == 0 && p->p_exitsig != 0) {
exit_psignal(p, q, &ksi);
mutex_enter(&proclist_mutex);
kpsignal(q, &ksi, NULL);
mutex_exit(&proclist_mutex);
}
/* Calculate the final rusage info. */
calcru(p, &p->p_stats->p_ru.ru_utime, &p->p_stats->p_ru.ru_stime,
NULL, NULL);
if (wakeinit)
cv_signal(&initproc->p_waitcv);
/*
* Remaining lwp resources will be freed in lwp_exit2() once we've
* switch to idle context; at that point, we will be marked as a
* full blown zombie.
*
* XXXSMP disable preemption.
*/
mutex_enter(&p->p_smutex);
lwp_drainrefs(l);
lwp_lock(l);
l->l_prflag &= ~LPR_DETACHED;
l->l_stat = LSZOMB;
lwp_unlock(l);
KASSERT(curlwp == l);
KASSERT(p->p_nrlwps == 1);
KASSERT(p->p_nlwps == 1);
p->p_stat = SZOMB;
p->p_nrlwps--;
p->p_nzlwps++;
p->p_ndlwps = 0;
mutex_exit(&p->p_smutex);
/*
* Signal the parent to collect us, and drop the proclist lock.
*/
cv_signal(&p->p_pptr->p_waitcv);
mutex_exit(&proclist_lock);
/* Verify that we hold no locks other than the kernel lock. */
#ifdef MULTIPROCESSOR
LOCKDEBUG_BARRIER(&kernel_lock, 0);
#else
LOCKDEBUG_BARRIER(NULL, 0);
#endif
/*
* NOTE: WE ARE NO LONGER ALLOWED TO SLEEP!
*/
/*
* Give machine-dependent code a chance to free any MD LWP
* resources. This must be done before uvm_lwp_exit(), in
* case these resources are in the PCB.
*/
#ifndef __NO_CPU_LWP_FREE
cpu_lwp_free(l, 1);
#endif
pmap_deactivate(l);
/* This process no longer needs to hold the kernel lock. */
#ifdef notyet
/* XXXSMP hold in lwp_userret() */
KERNEL_UNLOCK_LAST(l);
#else
KERNEL_UNLOCK_ALL(l, NULL);
#endif
lwp_exit_switchaway(l);
}
void
exit_lwps(struct lwp *l)
{
struct proc *p;
struct lwp *l2;
int error;
lwpid_t waited;
#if defined(MULTIPROCESSOR)
int nlocks;
#endif
KERNEL_UNLOCK_ALL(l, &nlocks);
p = l->l_proc;
retry:
/*
* Interrupt LWPs in interruptable sleep, unsuspend suspended
* LWPs and then wait for everyone else to finish.
*/
LIST_FOREACH(l2, &p->p_lwps, l_sibling) {
if (l2 == l)
continue;
lwp_lock(l2);
l2->l_flag |= LW_WEXIT;
if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) ||
l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) {
/* setrunnable() will release the lock. */
setrunnable(l2);
DPRINTF(("exit_lwps: Made %d.%d runnable\n",
p->p_pid, l2->l_lid));
continue;
}
lwp_unlock(l2);
}
while (p->p_nlwps > 1) {
DPRINTF(("exit_lwps: waiting for %d LWPs (%d zombies)\n",
p->p_nlwps, p->p_nzlwps));
error = lwp_wait1(l, 0, &waited, LWPWAIT_EXITCONTROL);
if (p->p_nlwps == 1)
break;
if (error == EDEADLK) {
/*
* LWPs can get suspended/slept behind us.
* (eg. sa_setwoken)
* kick them again and retry.
*/
goto retry;
}
if (error)
panic("exit_lwps: lwp_wait1 failed with error %d",
error);
DPRINTF(("exit_lwps: Got LWP %d from lwp_wait1()\n", waited));
}
KERNEL_LOCK(nlocks, l);
}
int
do_sys_wait(struct lwp *l, int *pid, int *status, int options,
struct rusage *ru, int *was_zombie)
{
struct proc *child;
int error;
mutex_enter(&proclist_lock);
error = find_stopped_child(l->l_proc, *pid, options, &child, status);
if (child == NULL) {
mutex_exit(&proclist_lock);
*pid = 0;
return error;
}
*pid = child->p_pid;
if (child->p_stat == SZOMB) {
/* proc_free() will release the proclist_lock. */
*was_zombie = 1;
if (options & WNOWAIT)
mutex_exit(&proclist_lock);
else {
KERNEL_LOCK(1, l); /* XXXSMP */
proc_free(child, ru);
KERNEL_UNLOCK_ONE(l); /* XXXSMP */
}
} else {
/* Child state must have been SSTOP. */
*was_zombie = 0;
mutex_exit(&proclist_lock);
*status = W_STOPCODE(*status);
}
return 0;
}
int
sys_wait4(struct lwp *l, void *v, register_t *retval)
{
struct sys_wait4_args /* {
syscallarg(int) pid;
syscallarg(int *) status;
syscallarg(int) options;
syscallarg(struct rusage *) rusage;
} */ *uap = v;
int status, error;
int was_zombie;
struct rusage ru;
error = do_sys_wait(l, &SCARG(uap, pid), &status, SCARG(uap, options),
SCARG(uap, rusage) != NULL ? &ru : NULL, &was_zombie);
retval[0] = SCARG(uap, pid);
if (SCARG(uap, pid) == 0)
return error;
if (SCARG(uap, rusage))
error = copyout(&ru, SCARG(uap, rusage), sizeof(ru));
if (error == 0 && SCARG(uap, status))
error = copyout(&status, SCARG(uap, status), sizeof(status));
return error;
}
/*
* Scan list of child processes for a child process that has stopped or
* exited. Used by sys_wait4 and 'compat' equivalents.
*
* Must be called with the proclist_lock held, and may release
* while waiting.
*/
static int
find_stopped_child(struct proc *parent, pid_t pid, int options,
struct proc **child_p, int *status_p)
{
struct proc *child, *dead;
int error;
KASSERT(mutex_owned(&proclist_lock));
if (options & ~(WUNTRACED|WNOHANG|WALTSIG|WALLSIG)
&& !(options & WOPTSCHECKED)) {
*child_p = NULL;
return EINVAL;
}
if (pid == 0 && !(options & WOPTSCHECKED))
pid = -parent->p_pgid;
for (;;) {
error = ECHILD;
dead = NULL;
mutex_enter(&proclist_mutex);
LIST_FOREACH(child, &parent->p_children, p_sibling) {
if (pid >= 0) {
if (child->p_pid != pid) {
child = p_find(pid, PFIND_ZOMBIE |
PFIND_LOCKED);
if (child == NULL ||
child->p_pptr != parent) {
child = NULL;
break;
}
}
} else if (pid != WAIT_ANY && child->p_pgid != -pid) {
/* Child not in correct pgrp */
continue;
}
/*
* Wait for processes with p_exitsig != SIGCHLD
* processes only if WALTSIG is set; wait for
* processes with p_exitsig == SIGCHLD only
* if WALTSIG is clear.
*/
if (((options & WALLSIG) == 0) &&
(options & WALTSIG ? child->p_exitsig == SIGCHLD
: P_EXITSIG(child) != SIGCHLD)){
if (child->p_pid == pid) {
child = NULL;
break;
}
continue;
}
error = 0;
if ((options & WNOZOMBIE) == 0) {
if (child->p_stat == SZOMB)
break;
if (child->p_stat == SDEAD) {
/*
* We may occasionally arrive here
* after receiving a signal, but
* immediatley before the child
* process is zombified. The wait
* will be short, so avoid returning
* to userspace.
*/
dead = child;
}
}
if (child->p_stat == SSTOP &&
child->p_waited == 0 &&
(child->p_slflag & PSL_TRACED ||
options & WUNTRACED)) {
if ((options & WNOWAIT) == 0) {
child->p_waited = 1;
parent->p_nstopchild--;
}
break;
}
if (parent->p_nstopchild == 0 || child->p_pid == pid) {
child = NULL;
break;
}
}
if (child != NULL || error != 0 ||
((options & WNOHANG) != 0 && dead == NULL)) {
if (child != NULL) {
*status_p = child->p_xstat;
}
mutex_exit(&proclist_mutex);
*child_p = child;
return error;
}
/*
* Wait for another child process to stop.
*/
mutex_exit(&proclist_lock);
error = cv_wait_sig(&parent->p_waitcv, &proclist_mutex);
mutex_exit(&proclist_mutex);
mutex_enter(&proclist_lock);
if (error != 0) {
*child_p = NULL;
return error;
}
}
}
/*
* Free a process after parent has taken all the state info. Must be called
* with the proclist lock held, and will release before returning.
*
* *ru is returned to the caller, and must be freed by the caller.
*/
static void
proc_free(struct proc *p, struct rusage *ru)
{
struct plimit *plim;
struct pstats *pstats;
struct proc *parent;
struct lwp *l;
ksiginfo_t ksi;
kauth_cred_t cred;
struct vnode *vp;
uid_t uid;
KASSERT(mutex_owned(&proclist_lock));
KASSERT(p->p_nlwps == 1);
KASSERT(p->p_nzlwps == 1);
KASSERT(p->p_nrlwps == 0);
KASSERT(p->p_stat == SZOMB);
/*
* If we got the child via ptrace(2) or procfs, and
* the parent is different (meaning the process was
* attached, rather than run as a child), then we need
* to give it back to the old parent, and send the
* parent the exit signal. The rest of the cleanup
* will be done when the old parent waits on the child.
*/
if ((p->p_slflag & PSL_TRACED) != 0) {
parent = p->p_pptr;
if (p->p_opptr != parent){
mutex_enter(&p->p_smutex);
p->p_slflag &= ~(PSL_TRACED|PSL_FSTRACE|PSL_SYSCALL);
mutex_exit(&p->p_smutex);
parent = p->p_opptr;
if (parent == NULL)
parent = initproc;
proc_reparent(p, parent);
p->p_opptr = NULL;
if (p->p_exitsig != 0) {
exit_psignal(p, parent, &ksi);
mutex_enter(&proclist_mutex);
kpsignal(parent, &ksi, NULL);
mutex_exit(&proclist_mutex);
}
cv_signal(&parent->p_waitcv);
mutex_exit(&proclist_lock);
return;
}
}
/*
* Finally finished with old proc entry. Unlink it from its process
* group.
*/
leavepgrp(p);
parent = p->p_pptr;
sched_proc_exit(parent, p);
/*
* Add child times of exiting process onto its own times.
* This cannot be done any earlier else it might get done twice.
*/
ruadd(&p->p_stats->p_ru, &p->p_stats->p_cru);
ruadd(&parent->p_stats->p_cru, &p->p_stats->p_ru);
if (ru != NULL)
*ru = p->p_stats->p_ru;
p->p_xstat = 0;
/*
* At this point we are going to start freeing the final resources.
* If anyone tries to access the proc structure after here they will
* get a shock - bits are missing. Attempt to make it hard! We
* don't bother with any further locking past this point.
*/
mutex_enter(&proclist_mutex);
p->p_stat = SIDL; /* not even a zombie any more */
LIST_REMOVE(p, p_list); /* off zombproc */
parent = p->p_pptr;
p->p_pptr->p_nstopchild--;
mutex_exit(&proclist_mutex);
LIST_REMOVE(p, p_sibling);
uid = kauth_cred_getuid(p->p_cred);
vp = p->p_textvp;
cred = p->p_cred;
l = LIST_FIRST(&p->p_lwps);
mutex_destroy(&p->p_rasmutex);
mutex_destroy(&p->p_mutex);
mutex_destroy(&p->p_stmutex);
mutex_destroy(&p->p_smutex);
cv_destroy(&p->p_waitcv);
cv_destroy(&p->p_lwpcv);
cv_destroy(&p->p_refcv);
/*
* Delay release until after dropping the proclist lock.
*/
plim = p->p_limit;
pstats = p->p_stats;
/*
* Free the proc structure and let pid be reallocated. This will
* release the proclist_lock.
*/
proc_free_mem(p);
/*
* Decrement the count of procs running with this uid.
*/
(void)chgproccnt(uid, -1);
/*
* Release substructures.
*/
limfree(plim);
pstatsfree(pstats);
kauth_cred_free(cred);
kauth_cred_free(l->l_cred);
/*
* Release reference to text vnode
*/
if (vp)
vrele(vp);
/*
* Free the last LWP's resources.
*/
lwp_free(l, false, true);
/*
* Collect child u-areas.
*/
uvm_uarea_drain(false);
}
/*
* make process 'parent' the new parent of process 'child'.
*
* Must be called with proclist_lock lock held.
*/
void
proc_reparent(struct proc *child, struct proc *parent)
{
KASSERT(mutex_owned(&proclist_lock));
if (child->p_pptr == parent)
return;
mutex_enter(&proclist_mutex);
if (child->p_stat == SZOMB ||
(child->p_stat == SSTOP && !child->p_waited)) {
child->p_pptr->p_nstopchild--;
parent->p_nstopchild++;
}
mutex_exit(&proclist_mutex);
if (parent == initproc)
child->p_exitsig = SIGCHLD;
LIST_REMOVE(child, p_sibling);
LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
child->p_pptr = parent;
}
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