freebsd-skq/sys/kern/kern_exit.c
John Baldwin 06ad42b2f7 Close some races between procfs/ptrace and exit(2):
- Reorder the events in exit(2) slightly so that we trigger the S_EXIT
  stop event earlier.  After we have signalled that, we set P_WEXIT and
  then wait for any processes with a hold on the vmspace via PHOLD to
  release it.  PHOLD now KASSERT()'s that P_WEXIT is clear when it is
  invoked, and PRELE now does a wakeup if P_WEXIT is set and p_lock drops
  to zero.
- Change proc_rwmem() to require that the processing read from has its
  vmspace held via PHOLD by the caller and get rid of all the junk to
  screw around with the vmspace reference count as we no longer need it.
- In ptrace() and pseudofs(), treat a process with P_WEXIT set as if it
  doesn't exist.
- Only do one PHOLD in kern_ptrace() now, and do it earlier so it covers
  FIX_SSTEP() (since on alpha at least this can end up calling proc_rwmem()
  to clear an earlier single-step simualted via a breakpoint).  We only
  do one to avoid races.  Also, by making the EINVAL error for unknown
  requests be part of the default: case in the switch, the various
  switch cases can now just break out to return which removes a _lot_ of
  duplicated PRELE and proc unlocks, etc.  Also, it fixes at least one bug
  where a LWP ptrace command could return EINVAL with the proc lock still
  held.
- Changed the locking for ptrace_single_step(), ptrace_set_pc(), and
  ptrace_clear_single_step() to always be called with the proc lock
  held (it was a mixed bag previously).  Alpha and arm have to drop
  the lock while the mess around with breakpoints, but other archs
  avoid extra lock release/acquires in ptrace().  I did have to fix a
  couple of other consumers in kern_kse and a few other places to
  hold the proc lock and PHOLD.

Tested by:	ps (1 mostly, but some bits of 2-4 as well)
MFC after:	1 week
2006-02-22 18:57:50 +00:00

948 lines
24 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.
* 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
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_compat.h"
#include "opt_ktrace.h"
#include "opt_mac.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/sysproto.h>
#include <sys/eventhandler.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/vmmeter.h>
#include <sys/vnode.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/syslog.h>
#include <sys/ptrace.h>
#include <sys/acct.h> /* for acct_process() function prototype */
#include <sys/filedesc.h>
#include <sys/mac.h>
#include <sys/shm.h>
#include <sys/sem.h>
#ifdef KTRACE
#include <sys/ktrace.h>
#endif
#include <security/audit/audit.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>
/* Required to be non-static for SysVR4 emulator */
MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status");
/* Hook for NFS teardown procedure. */
void (*nlminfo_release_p)(struct proc *p);
/*
* exit --
* Death of process.
*
* MPSAFE
*/
void
sys_exit(struct thread *td, struct sys_exit_args *uap)
{
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(struct thread *td, int rv)
{
uint64_t new_switchtime;
struct proc *p, *nq, *q;
struct tty *tp;
struct vnode *ttyvp;
struct vmspace *vm;
struct vnode *vtmp;
#ifdef KTRACE
struct vnode *tracevp;
struct ucred *tracecred;
#endif
struct plimit *plim;
int locked, refcnt;
/*
* Drop Giant if caller has it. Eventually we should warn about
* being called with Giant held.
*/
while (mtx_owned(&Giant))
mtx_unlock(&Giant);
p = td->td_proc;
if (p == initproc) {
printf("init died (signal %d, exit %d)\n",
WTERMSIG(rv), WEXITSTATUS(rv));
panic("Going nowhere without my init!");
}
/*
* MUST abort all other threads before proceeding past here.
*/
PROC_LOCK(p);
if (p->p_flag & P_HADTHREADS) {
retry:
/*
* First check if some other thread got here before us..
* if so, act apropriatly, (exit or suspend);
*/
thread_suspend_check(0);
/*
* 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 entering the kernel from userspace will
* thread_exit() in trap(). Any thread attempting to
* 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 userret().
* 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(SINGLE_EXIT))
goto retry;
/*
* All other activity in this process is now stopped.
* Threading support has been turned off.
*/
}
/*
* Wakeup anyone in procfs' PIOCWAIT. They should have a hold
* on our vmspace, so we should block below until they have
* released their reference to us. Note that if they have
* requested S_EXIT stops we will block here until they ack
* via PIOCCONT.
*/
_STOPEVENT(p, S_EXIT, rv);
/*
* Note that we are exiting and do another wakeup of anyone in
* PIOCWAIT in case they aren't listening for S_EXIT stops or
* decided to wait again after we told them we are exiting.
*/
p->p_flag |= P_WEXIT;
wakeup(&p->p_stype);
/*
* 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_LOCK(p->p_pptr);
sigqueue_take(p->p_ksi);
PROC_UNLOCK(p->p_pptr);
PROC_UNLOCK(p);
#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, WEXITSTATUS(rv), 0);
AUDIT_SYSCALL_EXIT(0, td);
#endif
/* Are we a task leader? */
if (p == p->p_leader) {
mtx_lock(&ppeers_lock);
q = p->p_peers;
while (q != NULL) {
PROC_LOCK(q);
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);
}
/*
* 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?
*/
EVENTHANDLER_INVOKE(process_exit, 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);
stopprofclock(p);
p->p_flag &= ~(P_TRACED | P_PPWAIT);
/*
* 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);
msleep(&p->p_itcallout, &p->p_mtx, PWAIT, "ritwait", 0);
KASSERT(!timevalisset(&p->p_realtimer.it_value),
("realtime timer is still armed"));
}
sigqueue_flush(&p->p_sigqueue);
sigqueue_flush(&td->td_sigqueue);
PROC_UNLOCK(p);
/*
* Reset any sigio structures pointing to us as a result of
* F_SETOWN with our pid.
*/
mtx_lock(&Giant); /* XXX: not sure if needed */
funsetownlst(&p->p_sigiolst);
mtx_unlock(&Giant);
/*
* If this process has an nlminfo data area (for lockd), release it
*/
if (nlminfo_release_p != NULL && p->p_nlminfo != NULL)
(*nlminfo_release_p)(p);
/*
* Close open files and release open-file table.
* This may block!
*/
fdfree(td);
/*
* If this thread tickled GEOM, we need to wait for the giggling to
* stop before we return to userland
*/
if (td->td_pflags & TDP_GEOM)
g_waitidle();
/*
* Remove ourself from our leader's peer list and wake our leader.
*/
mtx_lock(&ppeers_lock);
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(p->p_leader);
}
mtx_unlock(&ppeers_lock);
/* 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.
*
* Processes sharing the same vmspace may exit in one order, and
* get cleaned up by vmspace_exit() in a different order. The
* last exiting process to reach this point releases as much of
* the environment as it can, and the last process cleaned up
* by vmspace_exit() (which decrements exitingcnt) cleans up the
* remainder.
*/
atomic_add_int(&vm->vm_exitingcnt, 1);
do
refcnt = vm->vm_refcnt;
while (!atomic_cmpset_int(&vm->vm_refcnt, refcnt, refcnt - 1));
if (refcnt == 1) {
shmexit(vm);
pmap_remove_pages(vmspace_pmap(vm), vm_map_min(&vm->vm_map),
vm_map_max(&vm->vm_map));
(void) vm_map_remove(&vm->vm_map, vm_map_min(&vm->vm_map),
vm_map_max(&vm->vm_map));
}
sx_xlock(&proctree_lock);
if (SESS_LEADER(p)) {
struct session *sp;
sp = p->p_session;
if (sp->s_ttyvp) {
locked = VFS_LOCK_GIANT(sp->s_ttyvp->v_mount);
/*
* Controlling process.
* Signal foreground pgrp,
* drain controlling terminal
* and revoke access to controlling terminal.
*/
if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) {
tp = sp->s_ttyp;
if (sp->s_ttyp->t_pgrp) {
PGRP_LOCK(sp->s_ttyp->t_pgrp);
pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1);
PGRP_UNLOCK(sp->s_ttyp->t_pgrp);
}
/* XXX tp should be locked. */
sx_xunlock(&proctree_lock);
(void) ttywait(tp);
sx_xlock(&proctree_lock);
/*
* The tty could have been revoked
* if we blocked.
*/
if (sp->s_ttyvp) {
ttyvp = sp->s_ttyvp;
SESS_LOCK(p->p_session);
sp->s_ttyvp = NULL;
SESS_UNLOCK(p->p_session);
sx_xunlock(&proctree_lock);
VOP_LOCK(ttyvp, LK_EXCLUSIVE, td);
VOP_REVOKE(ttyvp, REVOKEALL);
vput(ttyvp);
sx_xlock(&proctree_lock);
}
}
if (sp->s_ttyvp) {
ttyvp = sp->s_ttyvp;
SESS_LOCK(p->p_session);
sp->s_ttyvp = NULL;
SESS_UNLOCK(p->p_session);
vrele(ttyvp);
}
/*
* s_ttyp is not zero'd; we use this to indicate
* that the session once had a controlling terminal.
* (for logging and informational purposes)
*/
VFS_UNLOCK_GIANT(locked);
}
SESS_LOCK(p->p_session);
sp->s_leader = NULL;
SESS_UNLOCK(p->p_session);
}
fixjobc(p, p->p_pgrp, 0);
sx_xunlock(&proctree_lock);
(void)acct_process(td);
#ifdef KTRACE
/*
* Drain any pending records on the thread and release the trace
* file. It might be better if drain-and-clear were atomic.
*/
ktrprocexit(td);
PROC_LOCK(p);
mtx_lock(&ktrace_mtx);
p->p_traceflag = 0; /* don't trace the vrele() */
tracevp = p->p_tracevp;
p->p_tracevp = NULL;
tracecred = p->p_tracecred;
p->p_tracecred = NULL;
mtx_unlock(&ktrace_mtx);
PROC_UNLOCK(p);
if (tracevp != NULL) {
locked = VFS_LOCK_GIANT(tracevp->v_mount);
vrele(tracevp);
VFS_UNLOCK_GIANT(locked);
}
if (tracecred != NULL)
crfree(tracecred);
#endif
/*
* Release reference to text vnode
*/
if ((vtmp = p->p_textvp) != NULL) {
p->p_textvp = NULL;
locked = VFS_LOCK_GIANT(vtmp->v_mount);
vrele(vtmp);
VFS_UNLOCK_GIANT(locked);
}
/*
* Release our limits structure.
*/
PROC_LOCK(p);
plim = p->p_limit;
p->p_limit = NULL;
PROC_UNLOCK(p);
lim_free(plim);
/*
* 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);
/*
* Reparent all of our children to init.
*/
sx_xlock(&proctree_lock);
q = LIST_FIRST(&p->p_children);
if (q != NULL) /* only need this if any child is S_ZOMB */
wakeup(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 | P_STOPPED_TRACE);
psignal(q, SIGKILL);
}
PROC_UNLOCK(q);
}
/*
* Save exit status and finalize rusage info except for times,
* adding in child rusage info later when our time is locked.
*/
PROC_LOCK(p);
p->p_xstat = rv;
p->p_xthread = td;
p->p_stats->p_ru.ru_nvcsw++;
*p->p_ru = p->p_stats->p_ru;
/*
* Notify interested parties of our demise.
*/
KNOTE_LOCKED(&p->p_klist, NOTE_EXIT);
/*
* Just delete all entries in the p_klist. At this point we won't
* report any more events, and there are nasty race conditions that
* can beat us if we don't.
*/
knlist_clear(&p->p_klist, 1);
/*
* 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, initproc);
p->p_sigparent = SIGCHLD;
PROC_LOCK(p->p_pptr);
/*
* 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(pp);
} else
mtx_unlock(&p->p_pptr->p_sigacts->ps_mtx);
if (p->p_pptr == initproc)
psignal(p->p_pptr, SIGCHLD);
else if (p->p_sigparent != 0) {
if (p->p_sigparent == SIGCHLD)
childproc_exited(p);
else /* LINUX thread */
psignal(p->p_pptr, p->p_sigparent);
}
PROC_UNLOCK(p->p_pptr);
PROC_UNLOCK(p);
/*
* Finally, call machine-dependent code to release the remaining
* resources including address space.
* The address space is released by "vmspace_exitfree(p)" in
* vm_waitproc().
*/
cpu_exit(td);
WITNESS_WARN(WARN_PANIC, &proctree_lock.sx_object,
"process (pid %d) exiting", p->p_pid);
PROC_LOCK(p);
PROC_LOCK(p->p_pptr);
sx_xunlock(&proctree_lock);
/*
* 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);
mtx_lock_spin(&sched_lock);
p->p_state = PRS_ZOMBIE;
PROC_UNLOCK(p->p_pptr);
/* Do the same timestamp bookkeeping that mi_switch() would do. */
new_switchtime = cpu_ticks();
p->p_rux.rux_runtime += (new_switchtime - PCPU_GET(switchtime));
p->p_rux.rux_uticks += td->td_uticks;
p->p_rux.rux_sticks += td->td_sticks;
p->p_rux.rux_iticks += td->td_iticks;
PCPU_SET(switchtime, new_switchtime);
PCPU_SET(switchticks, ticks);
cnt.v_swtch++;
/* Add our usage into the usage of all our children. */
ruadd(p->p_ru, &p->p_rux, &p->p_stats->p_cru, &p->p_crux);
sched_exit(p->p_pptr, td);
/*
* Hopefully no one will try to deliver a signal to the process this
* late in the game.
*/
knlist_destroy(&p->p_klist);
/*
* 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
/*
* MPSAFE.
*/
int
abort2(struct thread *td, struct abort2_args *uap)
{
struct proc *p = td->td_proc;
struct sbuf *sb;
void *uargs[16];
int error, i, sig;
error = 0; /* satisfy compiler */
/*
* 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 (uap->nargs < 0 || uap->nargs > 16)
goto out;
if (uap->args == NULL)
goto out;
error = copyin(uap->args, uargs, uap->nargs * sizeof(void *));
if (error != 0)
goto out;
/*
* Limit size of 'reason' string to 128. Will fit even when
* maximal number of arguments was chosen to be logged.
*/
if (uap->why != NULL) {
error = sbuf_copyin(sb, uap->why, 128);
if (error < 0)
goto out;
} else {
sbuf_printf(sb, "(null)");
}
if (uap->nargs) {
sbuf_printf(sb, "(");
for (i = 0;i < uap->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, W_EXITCODE(0, sig));
return (0);
}
#ifdef COMPAT_43
/*
* The dirty work is handled by kern_wait().
*
* MPSAFE.
*/
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().
*
* MPSAFE.
*/
int
wait4(struct thread *td, struct wait_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)
error = copyout(&status, uap->status, sizeof(status));
if (uap->rusage != NULL && error == 0)
error = copyout(&ru, uap->rusage, sizeof(struct rusage));
return (error);
}
int
kern_wait(struct thread *td, pid_t pid, int *status, int options,
struct rusage *rusage)
{
struct proc *p, *q, *t;
int error, nfound;
AUDIT_ARG(pid, pid);
q = td->td_proc;
if (pid == 0) {
PROC_LOCK(q);
pid = -q->p_pgid;
PROC_UNLOCK(q);
}
if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WLINUXCLONE))
return (EINVAL);
loop:
if (q->p_flag & P_STATCHILD) {
PROC_LOCK(q);
q->p_flag &= ~P_STATCHILD;
PROC_UNLOCK(q);
}
nfound = 0;
sx_xlock(&proctree_lock);
LIST_FOREACH(p, &q->p_children, p_sibling) {
PROC_LOCK(p);
if (pid != WAIT_ANY &&
p->p_pid != pid && p->p_pgid != -pid) {
PROC_UNLOCK(p);
continue;
}
if (p_canwait(td, p)) {
PROC_UNLOCK(p);
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.
*/
if ((p->p_sigparent != SIGCHLD) ^
((options & WLINUXCLONE) != 0)) {
PROC_UNLOCK(p);
continue;
}
nfound++;
if (p->p_state == PRS_ZOMBIE) {
/*
* It is possible that the last thread of this
* process is still running on another CPU
* in thread_exit() after having dropped the process
* lock via PROC_UNLOCK() but before it has completed
* cpu_throw(). In that case, the other thread must
* still hold sched_lock, so simply by acquiring
* sched_lock once we will wait long enough for the
* thread to exit in that case.
*/
mtx_lock_spin(&sched_lock);
mtx_unlock_spin(&sched_lock);
td->td_retval[0] = p->p_pid;
if (status)
*status = p->p_xstat; /* convert to int */
if (rusage) {
*rusage = *p->p_ru;
calcru(p, &rusage->ru_utime, &rusage->ru_stime);
}
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.
*/
PROC_UNLOCK(p);
if (p->p_oppid && (t = pfind(p->p_oppid)) != NULL) {
PROC_LOCK(p);
p->p_oppid = 0;
proc_reparent(p, t);
PROC_UNLOCK(p);
tdsignal(t, NULL, SIGCHLD, p->p_ksi);
wakeup(t);
PROC_UNLOCK(t);
sx_xunlock(&proctree_lock);
return (0);
}
/*
* Remove other references to this process to ensure
* we have an exclusive reference.
*/
sx_xlock(&allproc_lock);
LIST_REMOVE(p, p_list); /* off zombproc */
sx_xunlock(&allproc_lock);
LIST_REMOVE(p, p_sibling);
leavepgrp(p);
sx_xunlock(&proctree_lock);
/*
* As a side effect of this lock, we know that
* all other writes to this proc are visible now, so
* no more locking is needed for p.
*/
PROC_LOCK(p);
p->p_xstat = 0; /* XXX: why? */
PROC_UNLOCK(p);
PROC_LOCK(q);
ruadd(&q->p_stats->p_cru, &q->p_crux, p->p_ru,
&p->p_rux);
PROC_UNLOCK(q);
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);
/*
* Free credentials, arguments, and sigacts.
*/
crfree(p->p_ucred);
p->p_ucred = NULL;
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_destroy_proc(p);
#endif
#ifdef AUDIT
audit_proc_free(p);
#endif
KASSERT(FIRST_THREAD_IN_PROC(p),
("kern_wait: no residual thread!"));
uma_zfree(proc_zone, p);
sx_xlock(&allproc_lock);
nprocs--;
sx_xunlock(&allproc_lock);
return (0);
}
mtx_lock_spin(&sched_lock);
if ((p->p_flag & P_STOPPED_SIG) &&
(p->p_suspcount == p->p_numthreads) &&
(p->p_flag & P_WAITED) == 0 &&
(p->p_flag & P_TRACED || options & WUNTRACED)) {
mtx_unlock_spin(&sched_lock);
p->p_flag |= P_WAITED;
sx_xunlock(&proctree_lock);
td->td_retval[0] = p->p_pid;
if (status)
*status = W_STOPCODE(p->p_xstat);
PROC_UNLOCK(p);
PROC_LOCK(q);
sigqueue_take(p->p_ksi);
PROC_UNLOCK(q);
return (0);
}
mtx_unlock_spin(&sched_lock);
if (options & WCONTINUED && (p->p_flag & P_CONTINUED)) {
sx_xunlock(&proctree_lock);
td->td_retval[0] = p->p_pid;
p->p_flag &= ~P_CONTINUED;
PROC_UNLOCK(p);
PROC_LOCK(q);
sigqueue_take(p->p_ksi);
PROC_UNLOCK(q);
if (status)
*status = SIGCONT;
return (0);
}
PROC_UNLOCK(p);
}
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);
sx_xunlock(&proctree_lock);
if (q->p_flag & P_STATCHILD) {
q->p_flag &= ~P_STATCHILD;
error = 0;
} else
error = msleep(q, &q->p_mtx, PWAIT | PCATCH, "wait", 0);
PROC_UNLOCK(q);
if (error)
return (error);
goto loop;
}
/*
* 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)
{
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;
}