NetBSD/sys/kern/kern_exit.c

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/* $NetBSD: kern_exit.c,v 1.90 2001/03/05 20:38:21 fvdl Exp $ */
/*-
* Copyright (c) 1998, 1999 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.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*
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* @(#)kern_exit.c 8.10 (Berkeley) 2/23/95
*/
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#include "opt_ktrace.h"
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#include "opt_sysv.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/map.h>
#include <sys/ioctl.h>
#include <sys/proc.h>
#include <sys/tty.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <sys/kernel.h>
#include <sys/ktrace.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>
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#include <sys/pool.h>
#include <sys/resourcevar.h>
#include <sys/ptrace.h>
#include <sys/acct.h>
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#include <sys/filedesc.h>
#include <sys/signalvar.h>
#include <sys/sched.h>
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#ifdef SYSVSHM
#include <sys/shm.h>
#endif
#ifdef SYSVSEM
#include <sys/sem.h>
#endif
#include <sys/mount.h>
#include <sys/syscallargs.h>
#include <machine/cpu.h>
#include <uvm/uvm_extern.h>
/*
* exit --
* Death of process.
*/
int
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sys_exit(struct proc *p, void *v, register_t *retval)
{
struct sys_exit_args /* {
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syscallarg(int) rval;
} */ *uap = v;
exit1(p, 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.
*/
void
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exit1(struct proc *p, int rv)
{
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struct proc *q, *nq;
int s;
if (__predict_false(p == initproc))
panic("init died (signal %d, exit %d)",
WTERMSIG(rv), WEXITSTATUS(rv));
#ifdef PGINPROF
vmsizmon();
#endif
if (p->p_flag & P_PROFIL)
stopprofclock(p);
p->p_ru = pool_get(&rusage_pool, PR_WAITOK);
/*
* If parent is waiting for us to exit or exec, P_PPWAIT is set; we
* wake up the parent early to avoid deadlock.
*/
p->p_flag |= P_WEXIT;
if (p->p_flag & P_PPWAIT) {
p->p_flag &= ~P_PPWAIT;
wakeup((caddr_t)p->p_pptr);
}
sigfillset(&p->p_sigctx.ps_sigignore);
sigemptyset(&p->p_sigctx.ps_siglist);
p->p_sigctx.ps_sigcheck = 0;
callout_stop(&p->p_realit_ch);
/*
* Close open files and release open-file table.
* This may block!
*/
fdfree(p);
cwdfree(p);
#ifdef SYSVSEM
semexit(p);
#endif
if (SESS_LEADER(p)) {
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struct session *sp = p->p_session;
if (sp->s_ttyvp) {
/*
* Controlling process.
* Signal foreground pgrp,
* drain controlling terminal
* and revoke access to controlling terminal.
*/
if (sp->s_ttyp->t_session == sp) {
if (sp->s_ttyp->t_pgrp)
pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1);
(void) ttywait(sp->s_ttyp);
/*
* The tty could have been revoked
* if we blocked.
*/
if (sp->s_ttyvp)
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VOP_REVOKE(sp->s_ttyvp, REVOKEALL);
}
if (sp->s_ttyvp)
vrele(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;
}
fixjobc(p, p->p_pgrp, 0);
(void)acct_process(p);
#ifdef KTRACE
/*
* release trace file
*/
ktrderef(p);
#endif
/*
* NOTE: WE ARE NO LONGER ALLOWED TO SLEEP!
*/
p->p_stat = SDEAD;
/*
* Remove proc from pidhash chain so looking it up won't
* work. Move it from allproc to zombproc, but do not yet
* wake up the reaper. We will put the proc on the
* deadproc list later (using the p_hash member), and
* wake up the reaper when we do.
*/
s = proclist_lock_write();
LIST_REMOVE(p, p_hash);
LIST_REMOVE(p, p_list);
LIST_INSERT_HEAD(&zombproc, p, p_list);
proclist_unlock_write(s);
/*
* Give orphaned children to init(8).
*/
q = p->p_children.lh_first;
if (q) /* only need this if any child is S_ZOMB */
wakeup((caddr_t)initproc);
for (; q != 0; q = nq) {
nq = q->p_sibling.le_next;
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proc_reparent(q, initproc);
/*
* Traced processes are killed
* since their existence means someone is screwing up.
*/
if (q->p_flag & P_TRACED) {
q->p_flag &= ~(P_TRACED|P_WAITED|P_FSTRACE);
psignal(q, SIGKILL);
}
}
/*
* Save exit status and final rusage info, adding in child rusage
* info and self times.
*/
p->p_xstat = rv;
*p->p_ru = p->p_stats->p_ru;
calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL);
ruadd(p->p_ru, &p->p_stats->p_cru);
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/*
* 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 (p->p_pptr->p_flag & P_NOCLDWAIT) {
struct proc *pp = p->p_pptr;
proc_reparent(p, initproc);
/*
* If this was the last child of our parent, notify
* parent, so in case he was wait(2)ing, he will
* continue.
*/
if (pp->p_children.lh_first == NULL)
wakeup((caddr_t)pp);
}
/*
* Release the process's signal state.
*/
sigactsfree(p);
/*
* Clear curproc after we've done all operations
* that could block, and before tearing down the rest
* of the process state that might be used from clock, etc.
* Also, can't clear curproc while we're still runnable,
* as we're not on a run queue (we are current, just not
* a proper proc any longer!).
*
* Other substructures are freed from wait().
*/
curproc = NULL;
limfree(p->p_limit);
p->p_limit = NULL;
/*
* If emulation has process exit hook, call it now.
*/
if (p->p_emul->e_proc_exit)
(*p->p_emul->e_proc_exit)(p);
/* This process no longer needs to hold the kernel lock. */
KERNEL_PROC_UNLOCK(p);
/*
* Finally, call machine-dependent code to switch to a new
* context (possibly the idle context). Once we are no longer
* using the dead process's vmspace and stack, exit2() will be
* called to schedule those resources to be released by the
* reaper thread.
*
* Note that cpu_exit() will end with a call equivalent to
* cpu_switch(), finishing our execution (pun intended).
*/
cpu_exit(p);
}
/*
* We are called from cpu_exit() once it is safe to schedule the
* dead process's resources to be freed (i.e., once we've switched to
* the idle PCB for the current CPU).
*
* NOTE: One must be careful with locking in this routine. It's
* called from a critical section in machine-dependent code, so
* we should refrain from changing any interrupt state.
*
* We lock the deadproc list (a spin lock), place the proc on that
* list (using the p_hash member), and wake up the reaper.
*/
void
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exit2(struct proc *p)
{
simple_lock(&deadproc_slock);
LIST_INSERT_HEAD(&deadproc, p, p_hash);
simple_unlock(&deadproc_slock);
wakeup(&deadproc);
}
/*
* Process reaper. This is run by a kernel thread to free the resources
* of a dead process. Once the resources are free, the process becomes
* a zombie, and the parent is allowed to read the undead's status.
*/
void
reaper(void *arg)
{
struct proc *p;
KERNEL_PROC_UNLOCK(curproc);
for (;;) {
simple_lock(&deadproc_slock);
p = LIST_FIRST(&deadproc);
if (p == NULL) {
/* No work for us; go to sleep until someone exits. */
(void) ltsleep(&deadproc, PVM|PNORELOCK,
"reaper", 0, &deadproc_slock);
continue;
}
/* Remove us from the deadproc list. */
LIST_REMOVE(p, p_hash);
simple_unlock(&deadproc_slock);
KERNEL_PROC_LOCK(curproc);
/*
* Give machine-dependent code a chance to free any
* resources it couldn't free while still running on
* that process's context. This must be done before
* uvm_exit(), in case these resources are in the PCB.
*/
cpu_wait(p);
/*
* Free the VM resources we're still holding on to.
* We must do this from a valid thread because doing
* so may block.
*/
uvm_exit(p);
/* Process is now a true zombie. */
p->p_stat = SZOMB;
/* Wake up the parent so it can get exit status. */
if ((p->p_flag & P_FSTRACE) == 0 && p->p_exitsig != 0)
psignal(p->p_pptr, P_EXITSIG(p));
KERNEL_PROC_UNLOCK(curproc);
wakeup((caddr_t)p->p_pptr);
}
}
int
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sys_wait4(struct proc *q, void *v, register_t *retval)
{
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struct sys_wait4_args /* {
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syscallarg(int) pid;
syscallarg(int *) status;
syscallarg(int) options;
syscallarg(struct rusage *) rusage;
} */ *uap = v;
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struct proc *p, *t;
int nfound, status, error, s;
if (SCARG(uap, pid) == 0)
SCARG(uap, pid) = -q->p_pgid;
if (SCARG(uap, options) &~ (WUNTRACED|WNOHANG|WALTSIG))
return (EINVAL);
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loop:
nfound = 0;
for (p = q->p_children.lh_first; p != 0; p = p->p_sibling.le_next) {
if (SCARG(uap, pid) != WAIT_ANY &&
p->p_pid != SCARG(uap, pid) &&
p->p_pgid != -SCARG(uap, pid))
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 ((SCARG(uap, options) & WALTSIG) ?
(p->p_exitsig == SIGCHLD) : (P_EXITSIG(p) != SIGCHLD))
continue;
nfound++;
if (p->p_stat == SZOMB) {
retval[0] = p->p_pid;
if (SCARG(uap, status)) {
status = p->p_xstat; /* convert to int */
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error = copyout((caddr_t)&status,
(caddr_t)SCARG(uap, status),
sizeof(status));
if (error)
return (error);
}
if (SCARG(uap, rusage) &&
(error = copyout((caddr_t)p->p_ru,
(caddr_t)SCARG(uap, rusage),
sizeof(struct rusage))))
return (error);
/*
* 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_flag & P_TRACED) &&
p->p_oppid != p->p_pptr->p_pid) {
t = pfind(p->p_oppid);
proc_reparent(p, t ? t : initproc);
p->p_oppid = 0;
p->p_flag &= ~(P_TRACED|P_WAITED|P_FSTRACE);
if (p->p_exitsig != 0)
psignal(p->p_pptr, P_EXITSIG(p));
wakeup((caddr_t)p->p_pptr);
return (0);
}
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scheduler_wait_hook(q, p);
p->p_xstat = 0;
ruadd(&q->p_stats->p_cru, p->p_ru);
pool_put(&rusage_pool, p->p_ru);
/*
* Finally finished with old proc entry.
* Unlink it from its process group and free it.
*/
leavepgrp(p);
s = proclist_lock_write();
LIST_REMOVE(p, p_list); /* off zombproc */
proclist_unlock_write(s);
LIST_REMOVE(p, p_sibling);
/*
* Decrement the count of procs running with this uid.
*/
(void)chgproccnt(p->p_cred->p_ruid, -1);
/*
* Free up credentials.
*/
if (--p->p_cred->p_refcnt == 0) {
crfree(p->p_cred->pc_ucred);
pool_put(&pcred_pool, p->p_cred);
}
/*
* Release reference to text vnode
*/
if (p->p_textvp)
vrele(p->p_textvp);
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pool_put(&proc_pool, p);
nprocs--;
return (0);
}
if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 &&
(p->p_flag & P_TRACED || SCARG(uap, options) & WUNTRACED)) {
p->p_flag |= P_WAITED;
retval[0] = p->p_pid;
if (SCARG(uap, status)) {
status = W_STOPCODE(p->p_xstat);
error = copyout((caddr_t)&status,
(caddr_t)SCARG(uap, status),
sizeof(status));
} else
error = 0;
return (error);
}
}
if (nfound == 0)
return (ECHILD);
if (SCARG(uap, options) & WNOHANG) {
retval[0] = 0;
return (0);
}
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if ((error = tsleep((caddr_t)q, PWAIT | PCATCH, "wait", 0)) != 0)
return (error);
goto loop;
}
/*
* make process 'parent' the new parent of process 'child'.
*/
void
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proc_reparent(struct proc *child, struct proc *parent)
{
if (child->p_pptr == parent)
return;
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;
}