freebsd-skq/sys/kern/kern_exit.c
John Baldwin 8e2e767b1f Add a per-thread ucred reference for syscalls and synchronous traps from
userland.  The per thread ucred reference is immutable and thus needs no
locks to be read.  However, until all the proc locking associated with
writes to p_ucred are completed, it is still not safe to use the per-thread
reference.

Tested on:	x86 (SMP), alpha, sparc64
2001-10-26 08:12:54 +00:00

746 lines
18 KiB
C

/*
* 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.
*
* @(#)kern_exit.c 8.7 (Berkeley) 2/12/94
* $FreeBSD$
*/
#include "opt_compat.h"
#include "opt_ktrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/lock.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/pioctl.h>
#include <sys/tty.h>
#include <sys/wait.h>
#include <sys/vnode.h>
#include <sys/vmmeter.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/sx.h>
#include <sys/ptrace.h>
#include <sys/acct.h> /* for acct_process() function prototype */
#include <sys/filedesc.h>
#include <sys/shm.h>
#include <sys/sem.h>
#include <sys/aio.h>
#include <sys/jail.h>
#include <vm/vm.h>
#include <vm/vm_param.h>
#include <vm/vm_extern.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <vm/vm_zone.h>
#include <sys/user.h>
/* Required to be non-static for SysVR4 emulator */
MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status");
static MALLOC_DEFINE(M_ATEXIT, "atexit", "atexit callback");
static int wait1 __P((struct thread *, struct wait_args *, int));
/*
* callout list for things to do at exit time
*/
struct exitlist {
exitlist_fn function;
TAILQ_ENTRY(exitlist) next;
};
TAILQ_HEAD(exit_list_head, exitlist);
static struct exit_list_head exit_list = TAILQ_HEAD_INITIALIZER(exit_list);
/*
* exit --
* Death of process.
*
* MPSAFE
*/
void
sys_exit(td, uap)
struct thread *td;
struct sys_exit_args /* {
int rval;
} */ *uap;
{
mtx_lock(&Giant);
exit1(td, W_EXITCODE(uap->rval, 0));
/* NOTREACHED */
}
/*
* 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(td, rv)
register struct thread *td;
int rv;
{
struct proc *p = td->td_proc;
register struct proc *q, *nq;
register struct vmspace *vm;
struct vnode *vtmp;
struct exitlist *ep;
GIANT_REQUIRED;
if (p->p_pid == 1) {
printf("init died (signal %d, exit %d)\n",
WTERMSIG(rv), WEXITSTATUS(rv));
panic("Going nowhere without my init!");
}
/* XXXXKSE */
/* MUST abort all other threads before proceeding past this point */
aio_proc_rundown(p);
/* are we a task leader? */
PROC_LOCK(p);
if(p == p->p_leader) {
q = p->p_peers;
while (q != NULL) {
PROC_LOCK(q);
psignal(q, SIGKILL);
PROC_UNLOCK(q);
q = q->p_peers;
}
while (p->p_peers)
msleep((caddr_t)p, &p->p_mtx, PWAIT, "exit1", 0);
}
PROC_UNLOCK(p);
#ifdef PGINPROF
vmsizmon();
#endif
STOPEVENT(p, S_EXIT, rv);
wakeup(&p->p_stype); /* Wakeup anyone in procfs' PIOCWAIT */
/*
* Check if any loadable modules need anything done at process exit.
* e.g. SYSV IPC stuff
* XXX what if one of these generates an error?
*/
TAILQ_FOREACH(ep, &exit_list, next)
(*ep->function)(p);
stopprofclock(p);
MALLOC(p->p_ru, struct rusage *, sizeof(struct rusage),
M_ZOMBIE, M_WAITOK);
/*
* If parent is waiting for us to exit or exec,
* P_PPWAIT is set; we will wakeup the parent below.
*/
PROC_LOCK(p);
p->p_flag &= ~(P_TRACED | P_PPWAIT);
p->p_flag |= P_WEXIT;
SIGEMPTYSET(p->p_siglist);
PROC_UNLOCK(p);
if (timevalisset(&p->p_realtimer.it_value))
callout_stop(&p->p_itcallout);
/*
* Reset any sigio structures pointing to us as a result of
* F_SETOWN with our pid.
*/
funsetownlst(&p->p_sigiolst);
/*
* Close open files and release open-file table.
* This may block!
*/
fdfree(&p->p_thread); /* XXXKSE */
/*
* Remove ourself from our leader's peer list and wake our leader.
*/
PROC_LOCK(p->p_leader);
if(p->p_leader->p_peers) {
q = p->p_leader;
while(q->p_peers != p)
q = q->p_peers;
q->p_peers = p->p_peers;
wakeup((caddr_t)p->p_leader);
}
PROC_UNLOCK(p->p_leader);
/*
* XXX Shutdown SYSV semaphores
*/
semexit(p);
/* The next two chunks should probably be moved to vmspace_exit. */
vm = p->p_vmspace;
/*
* Release user portion of address space.
* This releases references to vnodes,
* which could cause I/O if the file has been unlinked.
* Need to do this early enough that we can still sleep.
* Can't free the entire vmspace as the kernel stack
* may be mapped within that space also.
*/
if (vm->vm_refcnt == 1) {
if (vm->vm_shm)
shmexit(p);
pmap_remove_pages(vmspace_pmap(vm), VM_MIN_ADDRESS,
VM_MAXUSER_ADDRESS);
(void) vm_map_remove(&vm->vm_map, VM_MIN_ADDRESS,
VM_MAXUSER_ADDRESS);
}
PROC_LOCK(p);
if (SESS_LEADER(p)) {
register struct session *sp = p->p_session;
PROC_UNLOCK(p);
if (sp->s_ttyvp) {
/*
* Controlling process.
* Signal foreground pgrp,
* drain controlling terminal
* and revoke access to controlling terminal.
*/
if (sp->s_ttyp && (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)
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;
} else
PROC_UNLOCK(p);
fixjobc(p, p->p_pgrp, 0);
(void)acct_process(td);
#ifdef KTRACE
/*
* release trace file
*/
p->p_traceflag = 0; /* don't trace the vrele() */
if ((vtmp = p->p_tracep) != NULL) {
p->p_tracep = NULL;
vrele(vtmp);
}
#endif
/*
* Remove proc from allproc queue and pidhash chain.
* Place onto zombproc. Unlink from parent's child list.
*/
sx_xlock(&allproc_lock);
LIST_REMOVE(p, p_list);
LIST_INSERT_HEAD(&zombproc, p, p_list);
LIST_REMOVE(p, p_hash);
sx_xunlock(&allproc_lock);
sx_xlock(&proctree_lock);
q = LIST_FIRST(&p->p_children);
if (q != NULL) /* only need this if any child is S_ZOMB */
wakeup((caddr_t) initproc);
for (; q != NULL; q = nq) {
nq = LIST_NEXT(q, p_sibling);
PROC_LOCK(q);
proc_reparent(q, initproc);
q->p_sigparent = SIGCHLD;
/*
* Traced processes are killed
* since their existence means someone is screwing up.
*/
if (q->p_flag & P_TRACED) {
q->p_flag &= ~P_TRACED;
psignal(q, SIGKILL);
}
PROC_UNLOCK(q);
}
/*
* 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;
mtx_lock_spin(&sched_lock);
calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL);
mtx_unlock_spin(&sched_lock);
ruadd(p->p_ru, &p->p_stats->p_cru);
/*
* Pretend that an mi_switch() to the next process occurs now. We
* must set `switchtime' directly since we will call cpu_switch()
* directly. Set it now so that the rest of the exit time gets
* counted somewhere if possible.
*/
mtx_lock_spin(&sched_lock);
microuptime(PCPU_PTR(switchtime));
PCPU_SET(switchticks, ticks);
mtx_unlock_spin(&sched_lock);
/*
* notify interested parties of our demise.
*/
PROC_LOCK(p);
KNOTE(&p->p_klist, NOTE_EXIT);
/*
* Notify parent that we're gone. If parent has the PS_NOCLDWAIT
* flag set, notify process 1 instead (and hope it will handle
* this situation).
*/
if (p->p_pptr->p_procsig->ps_flag & PS_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 (LIST_EMPTY(&pp->p_children))
wakeup((caddr_t)pp);
}
PROC_LOCK(p->p_pptr);
if (p->p_sigparent && p->p_pptr != initproc)
psignal(p->p_pptr, p->p_sigparent);
else
psignal(p->p_pptr, SIGCHLD);
PROC_UNLOCK(p->p_pptr);
/*
* If this is a kthread, then wakeup anyone waiting for it to exit.
*/
if (p->p_flag & P_KTHREAD)
wakeup((caddr_t)p);
PROC_UNLOCK(p);
sx_xunlock(&proctree_lock);
/*
* 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().
*/
mtx_assert(&Giant, MA_OWNED);
if (--p->p_limit->p_refcnt == 0) {
FREE(p->p_limit, M_SUBPROC);
p->p_limit = NULL;
}
/*
* Release this thread's reference to the ucred. The actual proc
* reference will stay around until the proc is harvested by
* wait(). At this point the ucred is immutable (no other threads
* from this proc are around that can change it) so we leave the
* per-thread ucred pointer intact in case it is needed although
* in theory nothing should be using it at this point.
*/
crfree(td->td_ucred);
/*
* Finally, call machine-dependent code to release the remaining
* resources including address space, the kernel stack and pcb.
* The address space is released by "vmspace_free(p->p_vmspace)"
* in vm_waitproc();
*/
cpu_exit(td);
PROC_LOCK(p);
mtx_lock_spin(&sched_lock);
while (mtx_owned(&Giant))
mtx_unlock_flags(&Giant, MTX_NOSWITCH);
/*
* We have to wait until after releasing all locks before
* changing p_stat. If we block on a mutex then we will be
* back at SRUN when we resume and our parent will never
* harvest us.
*/
p->p_stat = SZOMB;
wakeup(p->p_pptr);
PROC_UNLOCK_NOSWITCH(p);
cnt.v_swtch++;
cpu_throw();
panic("exit1");
}
#ifdef COMPAT_43
/*
* MPSAFE, the dirty work is handled by wait1().
*/
int
owait(td, uap)
struct thread *td;
register struct owait_args /* {
int dummy;
} */ *uap;
{
struct wait_args w;
w.options = 0;
w.rusage = NULL;
w.pid = WAIT_ANY;
w.status = NULL;
return (wait1(td, &w, 1));
}
#endif /* COMPAT_43 */
/*
* MPSAFE, the dirty work is handled by wait1().
*/
int
wait4(td, uap)
struct thread *td;
struct wait_args *uap;
{
return (wait1(td, uap, 0));
}
/*
* MPSAFE
*/
static int
wait1(td, uap, compat)
register struct thread *td;
register struct wait_args /* {
int pid;
int *status;
int options;
struct rusage *rusage;
} */ *uap;
int compat;
{
register int nfound;
register struct proc *q, *p, *t;
int status, error;
mtx_lock(&Giant);
q = td->td_proc;
if (uap->pid == 0)
uap->pid = -q->p_pgid;
if (uap->options &~ (WUNTRACED|WNOHANG|WLINUXCLONE)) {
error = EINVAL;
goto done2;
}
loop:
nfound = 0;
sx_slock(&proctree_lock);
LIST_FOREACH(p, &q->p_children, p_sibling) {
if (uap->pid != WAIT_ANY &&
p->p_pid != uap->pid && p->p_pgid != -uap->pid)
continue;
/*
* 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.
*/
PROC_LOCK(p);
if ((p->p_sigparent != SIGCHLD) ^
((uap->options & WLINUXCLONE) != 0)) {
PROC_UNLOCK(p);
continue;
}
nfound++;
mtx_lock_spin(&sched_lock);
if (p->p_stat == SZOMB) {
/*
* charge childs scheduling cpu usage to parent
* XXXKSE assume only one thread & kse & ksegrp
* keep estcpu in each ksegrp
* so charge it to the ksegrp that did the wait
* since process estcpu is sum of all ksegrps,
* this is strictly as expected.
* Assume that the child process aggregated all
* tke estcpu into the 'build-in' ksegrp.
* XXXKSE
*/
if (curthread->td_proc->p_pid != 1) {
curthread->td_ksegrp->kg_estcpu =
ESTCPULIM(curthread->td_ksegrp->kg_estcpu +
p->p_ksegrp.kg_estcpu);
}
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
sx_sunlock(&proctree_lock);
td->td_retval[0] = p->p_pid;
#ifdef COMPAT_43
if (compat)
td->td_retval[1] = p->p_xstat;
else
#endif
if (uap->status) {
status = p->p_xstat; /* convert to int */
if ((error = copyout((caddr_t)&status,
(caddr_t)uap->status, sizeof(status)))) {
goto done2;
}
}
if (uap->rusage && (error = copyout((caddr_t)p->p_ru,
(caddr_t)uap->rusage, sizeof (struct rusage)))) {
goto done2;
}
/*
* If we got the child via a ptrace 'attach',
* we need to give it back to the old parent.
*/
sx_xlock(&proctree_lock);
if (p->p_oppid) {
if ((t = pfind(p->p_oppid)) != NULL) {
PROC_LOCK(p);
p->p_oppid = 0;
proc_reparent(p, t);
PROC_UNLOCK(p);
psignal(t, SIGCHLD);
wakeup((caddr_t)t);
PROC_UNLOCK(t);
sx_xunlock(&proctree_lock);
error = 0;
goto done2;
}
}
sx_xunlock(&proctree_lock);
PROC_LOCK(p);
p->p_xstat = 0;
PROC_UNLOCK(p);
ruadd(&q->p_stats->p_cru, p->p_ru);
FREE(p->p_ru, M_ZOMBIE);
p->p_ru = NULL;
/*
* Decrement the count of procs running with this uid.
*/
(void)chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
/*
* Release reference to text vnode
*/
if (p->p_textvp)
vrele(p->p_textvp);
/*
* Finally finished with old proc entry.
* Unlink it from its process group and free it.
*/
leavepgrp(p);
sx_xlock(&allproc_lock);
LIST_REMOVE(p, p_list); /* off zombproc */
sx_xunlock(&allproc_lock);
sx_xlock(&proctree_lock);
LIST_REMOVE(p, p_sibling);
sx_xunlock(&proctree_lock);
/*
* Free up credentials.
*/
crfree(p->p_ucred);
p->p_ucred = NULL;
/*
* Remove unused arguments
*/
if (p->p_args && --p->p_args->ar_ref == 0)
FREE(p->p_args, M_PARGS);
if (--p->p_procsig->ps_refcnt == 0) {
if (p->p_sigacts != &p->p_uarea->u_sigacts)
FREE(p->p_sigacts, M_SUBPROC);
FREE(p->p_procsig, M_SUBPROC);
p->p_procsig = NULL;
}
/*
* 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);
mtx_destroy(&p->p_mtx);
zfree(proc_zone, p);
nprocs--;
error = 0;
goto done2;
}
if (p->p_stat == SSTOP && (p->p_flag & P_WAITED) == 0 &&
(p->p_flag & P_TRACED || uap->options & WUNTRACED)) {
mtx_unlock_spin(&sched_lock);
p->p_flag |= P_WAITED;
PROC_UNLOCK(p);
sx_sunlock(&proctree_lock);
td->td_retval[0] = p->p_pid;
#ifdef COMPAT_43
if (compat) {
td->td_retval[1] = W_STOPCODE(p->p_xstat);
error = 0;
} else
#endif
if (uap->status) {
status = W_STOPCODE(p->p_xstat);
error = copyout((caddr_t)&status,
(caddr_t)uap->status, sizeof(status));
} else
error = 0;
goto done2;
}
mtx_unlock_spin(&sched_lock);
PROC_UNLOCK(p);
}
sx_sunlock(&proctree_lock);
if (nfound == 0) {
error = ECHILD;
goto done2;
}
if (uap->options & WNOHANG) {
td->td_retval[0] = 0;
error = 0;
goto done2;
}
if ((error = tsleep((caddr_t)q, PWAIT | PCATCH, "wait", 0)) != 0)
goto done2;
goto loop;
done2:
mtx_unlock(&Giant);
return(error);
}
/*
* Make process 'parent' the new parent of process 'child'.
* Must be called with an exclusive hold of proctree lock.
*/
void
proc_reparent(child, parent)
register struct proc *child;
register struct proc *parent;
{
sx_assert(&proctree_lock, SX_XLOCKED);
PROC_LOCK_ASSERT(child, MA_OWNED);
if (child->p_pptr == parent)
return;
LIST_REMOVE(child, p_sibling);
LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
child->p_pptr = parent;
}
/*
* The next two functions are to handle adding/deleting items on the
* exit callout list
*
* at_exit():
* Take the arguments given and put them onto the exit callout list,
* However first make sure that it's not already there.
* returns 0 on success.
*/
int
at_exit(function)
exitlist_fn function;
{
struct exitlist *ep;
#ifdef INVARIANTS
/* Be noisy if the programmer has lost track of things */
if (rm_at_exit(function))
printf("WARNING: exit callout entry (%p) already present\n",
function);
#endif
ep = malloc(sizeof(*ep), M_ATEXIT, M_NOWAIT);
if (ep == NULL)
return (ENOMEM);
ep->function = function;
TAILQ_INSERT_TAIL(&exit_list, ep, next);
return (0);
}
/*
* Scan the exit callout list for the given item and remove it.
* Returns the number of items removed (0 or 1)
*/
int
rm_at_exit(function)
exitlist_fn function;
{
struct exitlist *ep;
TAILQ_FOREACH(ep, &exit_list, next) {
if (ep->function == function) {
TAILQ_REMOVE(&exit_list, ep, next);
free(ep, M_ATEXIT);
return(1);
}
}
return (0);
}