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NetBSD/sys/kern/kern_exit.c

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/* $NetBSD: kern_exit.c,v 1.298 2023/10/08 12:38:58 ad Exp $ */
/*-
* Copyright (c) 1998, 1999, 2006, 2007, 2008, 2020, 2023
* 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.
*
* 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 1.298 2023/10/08 12:38:58 ad Exp $");
#include "opt_ktrace.h"
#include "opt_dtrace.h"
#include "opt_sysv.h"
#include <sys/param.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/fstrans.h>
#include <sys/vnode.h>
#include <sys/syslog.h>
#include <sys/pool.h>
#include <sys/uidinfo.h>
#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/kauth.h>
#include <sys/sleepq.h>
#include <sys/lock.h>
#include <sys/lockdebug.h>
#include <sys/ktrace.h>
#include <sys/cpu.h>
#include <sys/lwpctl.h>
#include <sys/atomic.h>
#include <sys/sdt.h>
#include <sys/psref.h>
#include <uvm/uvm_extern.h>
#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 *, idtype_t, id_t, int,
struct proc **, struct wrusage *, siginfo_t *);
static void proc_free(struct proc *, struct wrusage *);
/*
* DTrace SDT provider definitions
*/
SDT_PROVIDER_DECLARE(proc);
SDT_PROBE_DEFINE1(proc, kernel, , exit, "int");
/*
* Fill in the appropriate signal information, and signal the parent.
*/
/* XXX noclone works around a gcc 4.5 bug on arm */
static void __noclone
exit_psignal(struct proc *p, struct proc *pp, ksiginfo_t *ksi)
{
KSI_INIT(ksi);
if ((ksi->ksi_signo = P_EXITSIG(p)) == SIGCHLD) {
if (p->p_xsig) {
if (p->p_sflag & PS_COREDUMP)
ksi->ksi_code = CLD_DUMPED;
else
ksi->ksi_code = CLD_KILLED;
ksi->ksi_status = p->p_xsig;
} else {
ksi->ksi_code = CLD_EXITED;
ksi->ksi_status = p->p_xexit;
}
} else {
ksi->ksi_code = SI_USER;
ksi->ksi_status = p->p_xsig;
}
/*
* 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);
/* 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, const struct sys_exit_args *uap, register_t *retval)
{
/* {
syscallarg(int) rval;
} */
struct proc *p = l->l_proc;
/* Don't call exit1() multiple times in the same process. */
mutex_enter(p->p_lock);
if (p->p_sflag & PS_WEXIT) {
mutex_exit(p->p_lock);
lwp_exit(l);
}
/* exit1() will release the mutex. */
exit1(l, 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_lock held. Does not return.
*/
void
exit1(struct lwp *l, int exitcode, int signo)
{
struct proc *p, *child, *next_child, *old_parent, *new_parent;
struct pgrp *pgrp;
ksiginfo_t ksi;
ksiginfoq_t kq;
int wakeinit;
p = l->l_proc;
/* Verify that we hold no locks other than p->p_lock. */
LOCKDEBUG_BARRIER(p->p_lock, 0);
/* XXX Temporary: something is leaking kernel_lock. */
KERNEL_UNLOCK_ALL(l, NULL);
KASSERT(mutex_owned(p->p_lock));
KASSERT(p->p_vmspace != NULL);
if (__predict_false(p == initproc)) {
panic("init died (signal %d, exit %d)", signo, exitcode);
}
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 (__predict_false(p->p_sflag & PS_STOPEXIT)) {
KASSERT(l->l_blcnt == 0);
sigclearall(p, &contsigmask, &kq);
if (!mutex_tryenter(&proc_lock)) {
mutex_exit(p->p_lock);
mutex_enter(&proc_lock);
mutex_enter(p->p_lock);
}
p->p_waited = 0;
p->p_pptr->p_nstopchild++;
p->p_stat = SSTOP;
mutex_exit(&proc_lock);
lwp_lock(l);
p->p_nrlwps--;
l->l_stat = LSSTOP;
lwp_unlock(l);
mutex_exit(p->p_lock);
lwp_lock(l);
spc_lock(l->l_cpu);
mi_switch(l);
mutex_enter(p->p_lock);
}
/*
* Bin any remaining signals and mark the process as dying so it will
* not be found for, e.g. signals.
*/
sigfillset(&p->p_sigctx.ps_sigignore);
sigclearall(p, NULL, &kq);
p->p_stat = SDYING;
/*
* Perform any required thread cleanup. Do this early so
* anyone wanting to look us up by our global thread ID
* will fail to find us.
*
* N.B. this will unlock p->p_lock on our behalf.
*/
lwp_thread_cleanup(l);
ksiginfo_queue_drain(&kq);
/* Destroy any lwpctl info. */
if (p->p_lwpctl != NULL)
lwp_ctl_exit();
/*
* Drain all remaining references that procfs, ptrace and others may
* have on the process.
*/
rw_enter(&p->p_reflock, RW_WRITER);
DPRINTF(("%s: %d.%d exiting.\n", __func__, p->p_pid, l->l_lid));
ptimers_free(p, TIMERS_ALL);
#if defined(__HAVE_RAS)
ras_purgeall();
#endif
/*
* Close open files, release open-file table and free signal
* actions. This may block!
*/
fd_free();
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_lock);
ktrderef(p);
mutex_exit(&ktrace_lock);
}
#endif
p->p_xexit = exitcode;
p->p_xsig = signo;
/*
* 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)
*/
if (p->p_emul->e_proc_exit)
(*p->p_emul->e_proc_exit)(p);
/*
* 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.
*/
ruspace(p); /* Update our vm resource use */
uvm_proc_exit(p);
/*
* Stop profiling.
*/
if (__predict_false((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, PL_PPWAIT is set; we
* wake up the parent early to avoid deadlock. We can do this once
* the VM resources are released.
*/
mutex_enter(&proc_lock);
if (p->p_lflag & PL_PPWAIT) {
lwp_t *lp;
l->l_lwpctl = NULL; /* was on loan from blocked parent */
p->p_lflag &= ~PL_PPWAIT;
lp = p->p_vforklwp;
p->p_vforklwp = NULL;
lp->l_vforkwaiting = false;
cv_broadcast(&lp->l_waitcv);
}
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;
mutex_spin_enter(&tty_lock);
if (tp->t_session == sp) {
/* we can't guarantee the revoke will do this */
pgrp = tp->t_pgrp;
tp->t_pgrp = NULL;
tp->t_session = NULL;
mutex_spin_exit(&tty_lock);
if (pgrp != NULL) {
pgsignal(pgrp, SIGHUP, 1);
}
mutex_exit(&proc_lock);
(void) ttywait(tp);
mutex_enter(&proc_lock);
/* The tty could have been revoked. */
vprevoke = sp->s_ttyvp;
} else
mutex_spin_exit(&tty_lock);
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) {
if (vprevoke != NULL) {
/* Releases proc_lock. */
proc_sessrele(sp);
VOP_REVOKE(vprevoke, REVOKEALL);
} else
mutex_exit(&proc_lock);
if (vprele != NULL)
vrele(vprele);
mutex_enter(&proc_lock);
}
}
fixjobc(p, p->p_pgrp, 0);
/* Release fstrans private data. */
fstrans_lwp_dtor(l);
/*
* Finalize the last LWP's specificdata, as well as the
* specificdata for the proc itself.
*/
lwp_finispecific(l);
proc_finispecific(p);
/*
* 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 (__predict_false(p->p_slflag & PSL_CHTRACED)) {
struct proc *q;
PROCLIST_FOREACH(q, &allproc) {
if (q->p_opptr == p)
q->p_opptr = NULL;
}
PROCLIST_FOREACH(q, &zombproc) {
if (q->p_opptr == p)
q->p_opptr = NULL;
}
}
/*
* Give orphaned children to init(8).
*/
child = LIST_FIRST(&p->p_children);
wakeinit = (child != NULL);
for (; child != NULL; child = next_child) {
next_child = LIST_NEXT(child, 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 (__predict_false(child->p_slflag & PSL_TRACED)) {
mutex_enter(p->p_lock);
child->p_slflag &=
~(PSL_TRACED|PSL_SYSCALL);
mutex_exit(p->p_lock);
if (child->p_opptr != child->p_pptr) {
struct proc *t = child->p_opptr;
proc_reparent(child, t ? t : initproc);
child->p_opptr = NULL;
} else
proc_reparent(child, initproc);
killproc(child, "orphaned traced process");
} else
proc_reparent(child, initproc);
}
/*
* Move proc from allproc to zombproc, it's now nearly ready to be
* collected by parent.
*/
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;
/*
* Let anyone watching this DTrace probe know what we're
* on our way out.
*/
SDT_PROBE(proc, kernel, , exit,
((p->p_sflag & PS_COREDUMP) ? CLD_DUMPED :
(p->p_xsig ? CLD_KILLED : CLD_EXITED)),
0,0,0,0);
/* Put in front of parent's sibling list for parent to collect it */
old_parent = p->p_pptr;
old_parent->p_nstopchild++;
if (LIST_FIRST(&old_parent->p_children) != p) {
/* Put child where it can be found quickly */
LIST_REMOVE(p, p_sibling);
LIST_INSERT_HEAD(&old_parent->p_children, p, p_sibling);
}
/*
* Notify parent that we're gone. If parent has the P_NOCLDWAIT
* flag set, notify init instead (and hope it will handle
* this situation).
*/
if (old_parent->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(&old_parent->p_children) == NULL)
cv_broadcast(&old_parent->p_waitcv);
}
/* Reload parent pointer, since p may have been reparented above */
new_parent = p->p_pptr;
if (__predict_false(p->p_exitsig != 0)) {
exit_psignal(p, new_parent, &ksi);
kpsignal(new_parent, &ksi, NULL);
}
/* Calculate the final rusage info. */
calcru(p, &p->p_stats->p_ru.ru_utime, &p->p_stats->p_ru.ru_stime,
NULL, NULL);
callout_destroy(&l->l_timeout_ch);
/*
* Release any PCU resources before becoming a zombie.
*/
pcu_discard_all(l);
/*
* Notify other processes tracking us with a knote that
* we're exiting.
*
* N.B. we do this here because the process is now SDEAD,
* and thus cannot have any more knotes attached. Also,
* knote_proc_exit() expects that p->p_lock is already
* held (and will assert so).
*/
mutex_enter(p->p_lock);
if (!SLIST_EMPTY(&p->p_klist)) {
knote_proc_exit(p);
}
/* Free the LWP ID */
proc_free_lwpid(p, l->l_lid);
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_lock);
/*
* Signal the parent to collect us, and drop the proclist lock.
* Drop debugger/procfs lock; no new references can be gained.
*/
rw_exit(&p->p_reflock);
cv_broadcast(&p->p_pptr->p_waitcv);
mutex_exit(&proc_lock);
if (wakeinit)
cv_broadcast(&initproc->p_waitcv);
/*
* 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.
*/
cpu_lwp_free(l, 1);
/* Switch away into oblivion. */
lwp_lock(l);
spc_lock(l->l_cpu);
mi_switch(l);
panic("exit1");
}
void
exit_lwps(struct lwp *l)
{
proc_t *p = l->l_proc;
lwp_t *l2;
retry:
KASSERT(mutex_owned(p->p_lock));
/*
* 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;
lwp_need_userret(l2);
if ((l2->l_stat == LSSLEEP && (l2->l_flag & LW_SINTR)) ||
l2->l_stat == LSSUSPENDED || l2->l_stat == LSSTOP) {
l2->l_flag &= ~LW_DBGSUSPEND;
/* setrunnable() will release the lock. */
setrunnable(l2);
continue;
}
lwp_unlock(l2);
}
/*
* Wait for every LWP to exit. Note: LWPs can get suspended/slept
* behind us or there may even be new LWPs created. Therefore, a
* full retry is required on error.
*/
while (p->p_nlwps > 1) {
if (lwp_wait(l, 0, NULL, true)) {
goto retry;
}
}
KASSERT(p->p_nlwps == 1);
}
int
do_sys_waitid(idtype_t idtype, id_t id, int *pid, int *status, int options,
struct wrusage *wru, siginfo_t *si)
{
proc_t *child;
int error;
if (wru != NULL)
memset(wru, 0, sizeof(*wru));
if (si != NULL)
memset(si, 0, sizeof(*si));
mutex_enter(&proc_lock);
error = find_stopped_child(curproc, idtype, id, options, &child,
wru, si);
if (child == NULL) {
mutex_exit(&proc_lock);
*pid = 0;
*status = 0;
return error;
}
*pid = child->p_pid;
if (child->p_stat == SZOMB) {
/* Child is exiting */
*status = P_WAITSTATUS(child);
/* proc_free() will release the proc_lock. */
if (options & WNOWAIT) {
mutex_exit(&proc_lock);
} else {
proc_free(child, wru);
}
} else {
/* Don't mark SIGCONT if we are being stopped */
*status = (child->p_xsig == SIGCONT && child->p_stat != SSTOP) ?
W_CONTCODE() : W_STOPCODE(child->p_xsig);
mutex_exit(&proc_lock);
}
return 0;
}
int
do_sys_wait(int *pid, int *status, int options, struct rusage *ru)
{
idtype_t idtype;
id_t id;
int ret;
struct wrusage wru;
/*
* Translate the special pid values into the (idtype, pid)
* pair for wait6. The WAIT_MYPGRP case is handled by
* find_stopped_child() 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;
}
options |= WEXITED | WTRAPPED;
ret = do_sys_waitid(idtype, id, pid, status, options, ru ? &wru : NULL,
NULL);
if (ru)
*ru = wru.wru_self;
return ret;
}
int
sys___wait450(struct lwp *l, const struct sys___wait450_args *uap,
register_t *retval)
{
/* {
syscallarg(int) pid;
syscallarg(int *) status;
syscallarg(int) options;
syscallarg(struct rusage *) rusage;
} */
int error, status, pid = SCARG(uap, pid);
struct rusage ru;
error = do_sys_wait(&pid, &status, SCARG(uap, options),
SCARG(uap, rusage) != NULL ? &ru : NULL);
retval[0] = pid;
if (pid == 0) {
return error;
}
if (SCARG(uap, status)) {
error = copyout(&status, SCARG(uap, status), sizeof(status));
}
if (SCARG(uap, rusage) && error == 0) {
error = copyout(&ru, SCARG(uap, rusage), sizeof(ru));
}
return error;
}
int
sys_wait6(struct lwp *l, const struct sys_wait6_args *uap, register_t *retval)
{
/* {
syscallarg(idtype_t) idtype;
syscallarg(id_t) id;
syscallarg(int *) status;
syscallarg(int) options;
syscallarg(struct wrusage *) wru;
syscallarg(siginfo_t *) si;
} */
struct wrusage wru, *wrup;
siginfo_t si, *sip;
idtype_t idtype;
int pid;
id_t id;
int error, status;
idtype = SCARG(uap, idtype);
id = SCARG(uap, id);
if (SCARG(uap, wru) != NULL)
wrup = &wru;
else
wrup = NULL;
if (SCARG(uap, info) != NULL)
sip = &si;
else
sip = NULL;
/*
* We expect all callers of wait6() to know about WEXITED and
* WTRAPPED.
*/
error = do_sys_waitid(idtype, id, &pid, &status, SCARG(uap, options),
wrup, sip);
retval[0] = pid; /* tell userland who it was */
#if 0
/*
* should we copyout if there was no process, hence no useful data?
* We don't for an old style wait4() (etc) but I believe
* FreeBSD does for wait6(), so a tossup... Go with FreeBSD for now.
*/
if (pid == 0)
return error;
#endif
if (SCARG(uap, status) != NULL && error == 0)
error = copyout(&status, SCARG(uap, status), sizeof(status));
if (SCARG(uap, wru) != NULL && error == 0)
error = copyout(&wru, SCARG(uap, wru), sizeof(wru));
if (SCARG(uap, info) != NULL && error == 0)
error = copyout(&si, SCARG(uap, info), sizeof(si));
return error;
}
/*
* Find a process that matches the provided criteria, and fill siginfo
* and resources if found.
* Returns:
* -1: Not found, abort early
* 0: Not matched
* 1: Matched, there might be more matches
* 2: This is the only match
*/
static int
match_process(const struct proc *pp, struct proc **q, idtype_t idtype, id_t id,
int options, struct wrusage *wrusage, siginfo_t *siginfo)
{
struct rusage *rup;
struct proc *p = *q;
int rv = 1;
switch (idtype) {
case P_ALL:
mutex_enter(p->p_lock);
break;
case P_PID:
if (p->p_pid != (pid_t)id) {
p = *q = proc_find_raw((pid_t)id);
if (p == NULL || p->p_stat == SIDL || p->p_pptr != pp) {
*q = NULL;
return -1;
}
}
mutex_enter(p->p_lock);
rv++;
break;
case P_PGID:
if (p->p_pgid != (pid_t)id)
return 0;
mutex_enter(p->p_lock);
break;
case P_SID:
if (p->p_session->s_sid != (pid_t)id)
return 0;
mutex_enter(p->p_lock);
break;
case P_UID:
mutex_enter(p->p_lock);
if (kauth_cred_geteuid(p->p_cred) != (uid_t)id) {
mutex_exit(p->p_lock);
return 0;
}
break;
case P_GID:
mutex_enter(p->p_lock);
if (kauth_cred_getegid(p->p_cred) != (gid_t)id) {
mutex_exit(p->p_lock);
return 0;
}
break;
case P_CID:
case P_PSETID:
case P_CPUID:
/* XXX: Implement me */
default:
return 0;
}
if ((options & WEXITED) == 0 && p->p_stat == SZOMB) {
mutex_exit(p->p_lock);
return 0;
}
if (siginfo != NULL) {
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 (p->p_sflag & PS_COREDUMP) {
siginfo->si_code = CLD_DUMPED;
siginfo->si_status = p->p_xsig;
} else if (p->p_xsig) {
siginfo->si_code = CLD_KILLED;
siginfo->si_status = p->p_xsig;
} else {
siginfo->si_code = CLD_EXITED;
siginfo->si_status = p->p_xexit;
}
siginfo->si_pid = p->p_pid;
siginfo->si_uid = kauth_cred_geteuid(p->p_cred);
siginfo->si_utime = p->p_stats->p_ru.ru_utime.tv_sec;
siginfo->si_stime = p->p_stats->p_ru.ru_stime.tv_sec;
}
/*
* 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_stats->p_ru;
calcru(p, &rup->ru_utime, &rup->ru_stime, NULL, NULL);
rup = &wrusage->wru_children;
*rup = p->p_stats->p_cru;
calcru(p, &rup->ru_utime, &rup->ru_stime, NULL, NULL);
}
mutex_exit(p->p_lock);
return rv;
}
/*
* Determine if there are existing processes being debugged
* that used to be (and sometime later will be again) children
* of a specific parent (while matching wait criteria)
*/
static bool
debugged_child_exists(idtype_t idtype, id_t id, int options, siginfo_t *si,
const struct proc *parent)
{
struct proc *pp;
/*
* If we are searching for a specific pid, we can optimise a little
*/
if (idtype == P_PID) {
/*
* Check the specific process to see if its real parent is us
*/
pp = proc_find_raw((pid_t)id);
if (pp != NULL && pp->p_stat != SIDL && pp->p_opptr == parent) {
/*
* using P_ALL here avoids match_process() doing the
* same work that we just did, but incorrectly for
* this scenario.
*/
if (match_process(parent, &pp, P_ALL, id, options,
NULL, si))
return true;
}
return false;
}
/*
* For the hard cases, just look everywhere to see if some
* stolen (reparented) process is really our lost child.
* Then check if that process could satisfy the wait conditions.
*/
/*
* XXX inefficient, but hopefully fairly rare.
* XXX should really use a list of reparented processes.
*/
PROCLIST_FOREACH(pp, &allproc) {
if (pp->p_stat == SIDL) /* XXX impossible ?? */
continue;
if (pp->p_opptr == parent &&
match_process(parent, &pp, idtype, id, options, NULL, si))
return true;
}
PROCLIST_FOREACH(pp, &zombproc) {
if (pp->p_stat == SIDL) /* XXX impossible ?? */
continue;
if (pp->p_opptr == parent &&
match_process(parent, &pp, idtype, id, options, NULL, si))
return true;
}
return false;
}
/*
* 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 proc_lock held, and may release while waiting.
*/
static int
find_stopped_child(struct proc *parent, idtype_t idtype, id_t id, int options,
struct proc **child_p, struct wrusage *wru, siginfo_t *si)
{
struct proc *child, *dead;
int error;
KASSERT(mutex_owned(&proc_lock));
if (options & ~WALLOPTS) {
*child_p = NULL;
return EINVAL;
}
if ((options & WSELECTOPTS) == 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.
*/
*child_p = NULL;
return EINVAL;
}
if ((pid_t)id == WAIT_MYPGRP && (idtype == P_PID || idtype == P_PGID)) {
id = (id_t)parent->p_pgid;
idtype = P_PGID;
}
for (;;) {
error = ECHILD;
dead = NULL;
LIST_FOREACH(child, &parent->p_children, p_sibling) {
int rv = match_process(parent, &child, idtype, id,
options, wru, si);
if (rv == -1)
break;
if (rv == 0)
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 (rv == 2) {
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
* immediately before the child
* process is zombified. The wait
* will be short, so avoid returning
* to userspace.
*/
dead = child;
}
}
if ((options & WCONTINUED) != 0 &&
child->p_xsig == SIGCONT &&
(child->p_sflag & PS_CONTINUED)) {
if ((options & WNOWAIT) == 0) {
child->p_sflag &= ~PS_CONTINUED;
child->p_waited = 1;
parent->p_nstopchild--;
}
if (si) {
si->si_status = child->p_xsig;
si->si_code = CLD_CONTINUED;
}
break;
}
if ((options & (WTRAPPED|WSTOPPED)) != 0 &&
child->p_stat == SSTOP &&
child->p_waited == 0 &&
((child->p_slflag & PSL_TRACED) ||
options & (WUNTRACED|WSTOPPED))) {
if ((options & WNOWAIT) == 0) {
child->p_waited = 1;
parent->p_nstopchild--;
}
if (si) {
si->si_status = child->p_xsig;
si->si_code =
(child->p_slflag & PSL_TRACED) ?
CLD_TRAPPED : CLD_STOPPED;
}
break;
}
if (parent->p_nstopchild == 0 || rv == 2) {
child = NULL;
break;
}
}
/*
* If we found nothing, but we are the bereaved parent
* of a stolen child, look and see if that child (or
* one of them) meets our search criteria. If so, then
* we cannot succeed, but we can hang (wait...),
* or if WNOHANG, return 0 instead of ECHILD
*/
if (child == NULL && error == ECHILD &&
(parent->p_slflag & PSL_CHTRACED) &&
debugged_child_exists(idtype, id, options, si, parent))
error = 0;
if (child != NULL || error != 0 ||
((options & WNOHANG) != 0 && dead == NULL)) {
*child_p = child;
return error;
}
/*
* Wait for another child process to stop.
*/
error = cv_wait_sig(&parent->p_waitcv, &proc_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 wrusage *wru)
{
struct proc *parent = p->p_pptr;
struct lwp *l;
ksiginfo_t ksi;
kauth_cred_t cred1, cred2;
uid_t uid;
KASSERT(mutex_owned(&proc_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 && p->p_opptr != parent) {
mutex_enter(p->p_lock);
p->p_slflag &= ~(PSL_TRACED|PSL_SYSCALL);
mutex_exit(p->p_lock);
parent = (p->p_opptr == NULL) ? initproc : p->p_opptr;
proc_reparent(p, parent);
p->p_opptr = NULL;
if (p->p_exitsig != 0) {
exit_psignal(p, parent, &ksi);
kpsignal(parent, &ksi, NULL);
}
cv_broadcast(&parent->p_waitcv);
mutex_exit(&proc_lock);
return;
}
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.
*/
l = LIST_FIRST(&p->p_lwps);
ruadd(&p->p_stats->p_ru, &l->l_ru);
ruadd(&p->p_stats->p_ru, &p->p_stats->p_cru);
ruadd(&parent->p_stats->p_cru, &p->p_stats->p_ru);
if (wru != NULL) {
wru->wru_self = p->p_stats->p_ru;
wru->wru_children = p->p_stats->p_cru;
}
p->p_xsig = 0;
p->p_xexit = 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.
*/
p->p_stat = SIDL; /* not even a zombie any more */
LIST_REMOVE(p, p_list); /* off zombproc */
parent->p_nstopchild--;
LIST_REMOVE(p, p_sibling);
/*
* Let pid be reallocated.
*/
proc_free_pid(p->p_pid);
atomic_dec_uint(&nprocs);
/*
* Unlink process from its process group.
* Releases the proc_lock.
*/
proc_leavepgrp(p);
/*
* Delay release until after lwp_free.
*/
cred2 = l->l_cred;
/*
* Free the last LWP's resources.
*
* lwp_free ensures the LWP is no longer running on another CPU.
*/
lwp_free(l, false, true);
/*
* Now no one except us can reach the process p.
*/
/*
* Decrement the count of procs running with this uid.
*/
cred1 = p->p_cred;
uid = kauth_cred_getuid(cred1);
(void)chgproccnt(uid, -1);
/*
* Release substructures.
*/
lim_free(p->p_limit);
pstatsfree(p->p_stats);
kauth_cred_free(cred1);
kauth_cred_free(cred2);
/*
* Release reference to text vnode
*/
if (p->p_textvp)
vrele(p->p_textvp);
kmem_strfree(p->p_path);
mutex_destroy(&p->p_auxlock);
mutex_obj_free(p->p_lock);
mutex_destroy(&p->p_stmutex);
cv_destroy(&p->p_waitcv);
cv_destroy(&p->p_lwpcv);
rw_destroy(&p->p_reflock);
proc_free_mem(p);
}
/*
* Change the parent of a process for tracing purposes.
*/
void
proc_changeparent(struct proc *t, struct proc *p)
{
SET(t->p_slflag, PSL_TRACED);
t->p_opptr = t->p_pptr;
if (t->p_pptr == p)
return;
struct proc *parent = t->p_pptr;
if (parent->p_lock < t->p_lock) {
if (!mutex_tryenter(parent->p_lock)) {
mutex_exit(t->p_lock);
mutex_enter(parent->p_lock);
mutex_enter(t->p_lock);
}
} else if (parent->p_lock > t->p_lock) {
mutex_enter(parent->p_lock);
}
parent->p_slflag |= PSL_CHTRACED;
proc_reparent(t, p);
if (parent->p_lock != t->p_lock)
mutex_exit(parent->p_lock);
}
/*
* make process 'parent' the new parent of process 'child'.
*
* Must be called with proc_lock held.
*/
void
proc_reparent(struct proc *child, struct proc *parent)
{
KASSERT(mutex_owned(&proc_lock));
if (child->p_pptr == parent)
return;
if (child->p_stat == SZOMB || child->p_stat == SDEAD ||
(child->p_stat == SSTOP && !child->p_waited)) {
child->p_pptr->p_nstopchild--;
parent->p_nstopchild++;
}
if (parent == initproc) {
child->p_exitsig = SIGCHLD;
child->p_ppid = parent->p_pid;
}
LIST_REMOVE(child, p_sibling);
LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
child->p_pptr = parent;
}
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