2 * Copyright (c) 1982, 1986, 1989, 1991, 1993
3 * The Regents of the University of California. All rights reserved.
4 * (c) UNIX System Laboratories, Inc.
5 * All or some portions of this file are derived from material licensed
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7 * Co. or Unix System Laboratories, Inc. and are reproduced herein with
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34 * @(#)kern_exit.c 8.7 (Berkeley) 2/12/94
35 * $FreeBSD: src/sys/kern/kern_exit.c,v 1.92.2.11 2003/01/13 22:51:16 dillon Exp $
38 #include "opt_ktrace.h"
40 #include <sys/param.h>
41 #include <sys/systm.h>
42 #include <sys/sysproto.h>
43 #include <sys/kernel.h>
44 #include <sys/malloc.h>
46 #include <sys/ktrace.h>
47 #include <sys/pioctl.h>
50 #include <sys/vnode.h>
51 #include <sys/resourcevar.h>
52 #include <sys/signalvar.h>
53 #include <sys/taskqueue.h>
54 #include <sys/ptrace.h>
55 #include <sys/acct.h> /* for acct_process() function prototype */
56 #include <sys/filedesc.h>
60 #include <sys/kern_syscall.h>
61 #include <sys/unistd.h>
62 #include <sys/eventhandler.h>
63 #include <sys/dsched.h>
66 #include <vm/vm_param.h>
69 #include <vm/vm_map.h>
70 #include <vm/vm_extern.h>
72 #include <sys/refcount.h>
73 #include <sys/spinlock2.h>
75 #include <machine/vmm.h>
77 static void reaplwps(void *context
, int dummy
);
78 static void reaplwp(struct lwp
*lp
);
79 static void killlwps(struct lwp
*lp
);
81 static MALLOC_DEFINE(M_ATEXIT
, "atexit", "atexit callback");
84 * callout list for things to do at exit time
88 TAILQ_ENTRY(exitlist
) next
;
91 TAILQ_HEAD(exit_list_head
, exitlist
);
92 static struct exit_list_head exit_list
= TAILQ_HEAD_INITIALIZER(exit_list
);
97 static struct task
*deadlwp_task
[MAXCPU
];
98 static struct lwplist deadlwp_list
[MAXCPU
];
99 static struct lwkt_token deadlwp_token
[MAXCPU
];
101 void (*linux_task_drop_callback
)(thread_t td
);
102 void (*linux_proc_drop_callback
)(struct proc
*p
);
108 * SYS_EXIT_ARGS(int rval)
111 sys_exit(struct exit_args
*uap
)
113 exit1(W_EXITCODE(uap
->rval
, 0));
119 * Death of a lwp or process with optional bells and whistles.
122 sys_extexit(struct extexit_args
*uap
)
124 struct proc
*p
= curproc
;
128 action
= EXTEXIT_ACTION(uap
->how
);
129 who
= EXTEXIT_WHO(uap
->how
);
131 /* Check parameters before we might perform some action */
144 error
= copyout(&uap
->status
, uap
->addr
, sizeof(uap
->status
));
152 lwkt_gettoken(&p
->p_token
);
157 * Be sure only to perform a simple lwp exit if there is at
158 * least one more lwp in the proc, which will call exit1()
159 * later, otherwise the proc will be an UNDEAD and not even a
162 if (p
->p_nthreads
> 1) {
163 lwp_exit(0, NULL
); /* called w/ p_token held */
166 /* else last lwp in proc: do the real thing */
168 default: /* to help gcc */
170 lwkt_reltoken(&p
->p_token
);
171 exit1(W_EXITCODE(uap
->status
, 0));
176 lwkt_reltoken(&p
->p_token
); /* safety */
180 * Kill all lwps associated with the current process except the
181 * current lwp. Return an error if we race another thread trying to
182 * do the same thing and lose the race.
184 * If forexec is non-zero the current thread and process flags are
185 * cleaned up so they can be reused.
188 killalllwps(int forexec
)
190 struct lwp
*lp
= curthread
->td_lwp
;
191 struct proc
*p
= lp
->lwp_proc
;
195 * Interlock against P_WEXIT. Only one of the process's thread
196 * is allowed to do the master exit.
198 lwkt_gettoken(&p
->p_token
);
199 if (p
->p_flags
& P_WEXIT
) {
200 lwkt_reltoken(&p
->p_token
);
203 p
->p_flags
|= P_WEXIT
;
204 lwkt_gettoken(&lp
->lwp_token
);
207 * Set temporary stopped state in case we are racing a coredump.
208 * Otherwise the coredump may hang forever.
210 if (lp
->lwp_mpflags
& LWP_MP_WSTOP
) {
213 atomic_set_int(&lp
->lwp_mpflags
, LWP_MP_WSTOP
);
216 wakeup(&p
->p_nstopped
);
220 * Interlock with LWP_MP_WEXIT and kill any remaining LWPs
222 atomic_set_int(&lp
->lwp_mpflags
, LWP_MP_WEXIT
);
223 if (p
->p_nthreads
> 1)
227 * Undo temporary stopped state
229 if (fakestop
&& (lp
->lwp_mpflags
& LWP_MP_WSTOP
)) {
230 atomic_clear_int(&lp
->lwp_mpflags
, LWP_MP_WSTOP
);
235 * If doing this for an exec, clean up the remaining thread
236 * (us) for continuing operation after all the other threads
240 atomic_clear_int(&lp
->lwp_mpflags
, LWP_MP_WEXIT
);
241 p
->p_flags
&= ~P_WEXIT
;
243 lwkt_reltoken(&lp
->lwp_token
);
244 lwkt_reltoken(&p
->p_token
);
250 * Kill all LWPs except the current one. Do not try to signal
251 * LWPs which have exited on their own or have already been
255 killlwps(struct lwp
*lp
)
257 struct proc
*p
= lp
->lwp_proc
;
261 * Kill the remaining LWPs. We must send the signal before setting
262 * LWP_MP_WEXIT. The setting of WEXIT is optional but helps reduce
263 * races. tlp must be held across the call as it might block and
264 * allow the target lwp to rip itself out from under our loop.
266 FOREACH_LWP_IN_PROC(tlp
, p
) {
268 lwkt_gettoken(&tlp
->lwp_token
);
269 if ((tlp
->lwp_mpflags
& LWP_MP_WEXIT
) == 0) {
270 atomic_set_int(&tlp
->lwp_mpflags
, LWP_MP_WEXIT
);
271 lwpsignal(p
, tlp
, SIGKILL
);
273 lwkt_reltoken(&tlp
->lwp_token
);
278 * Wait for everything to clear out. Also make sure any tstop()s
279 * are signalled (we are holding p_token for the interlock).
282 while (p
->p_nthreads
> 1)
283 tsleep(&p
->p_nthreads
, 0, "killlwps", 0);
287 * Exit: deallocate address space and other resources, change proc state
288 * to zombie, and unlink proc from allproc and parent's lists. Save exit
289 * status and rusage for wait(). Check for child processes and orphan them.
294 struct thread
*td
= curthread
;
295 struct proc
*p
= td
->td_proc
;
296 struct lwp
*lp
= td
->td_lwp
;
300 struct sysreaper
*reap
;
306 lwkt_gettoken(&p
->p_token
);
309 kprintf("init died (signal %d, exit %d)\n",
310 WTERMSIG(rv
), WEXITSTATUS(rv
));
311 panic("Going nowhere without my init!");
313 varsymset_clean(&p
->p_varsymset
);
314 lockuninit(&p
->p_varsymset
.vx_lock
);
317 * Kill all lwps associated with the current process, return an
318 * error if we race another thread trying to do the same thing
321 error
= killalllwps(0);
327 /* are we a task leader? */
328 if (p
== p
->p_leader
) {
329 struct kill_args killArgs
;
330 killArgs
.signum
= SIGKILL
;
333 killArgs
.pid
= q
->p_pid
;
335 * The interface for kill is better
336 * than the internal signal
342 tsleep((caddr_t
)p
, 0, "exit1", 0);
348 STOPEVENT(p
, S_EXIT
, rv
);
349 p
->p_flags
|= P_POSTEXIT
; /* stop procfs stepping */
352 * Check if any loadable modules need anything done at process exit.
353 * e.g. SYSV IPC stuff
354 * XXX what if one of these generates an error?
359 * XXX: imho, the eventhandler stuff is much cleaner than this.
360 * Maybe we should move everything to use eventhandler.
362 TAILQ_FOREACH(ep
, &exit_list
, next
)
365 if (p
->p_flags
& P_PROFIL
)
368 SIGEMPTYSET(p
->p_siglist
);
369 SIGEMPTYSET(lp
->lwp_siglist
);
370 if (timevalisset(&p
->p_realtimer
.it_value
))
371 callout_terminate(&p
->p_ithandle
);
374 * Reset any sigio structures pointing to us as a result of
375 * F_SETOWN with our pid.
377 funsetownlst(&p
->p_sigiolst
);
380 * Close open files and release open-file table.
385 if (p
->p_leader
->p_peers
) {
387 while(q
->p_peers
!= p
)
389 q
->p_peers
= p
->p_peers
;
390 wakeup((caddr_t
)p
->p_leader
);
394 * XXX Shutdown SYSV semaphores
398 /* The next two chunks should probably be moved to vmspace_exit. */
402 * Clean up data related to virtual kernel operation. Clean up
403 * any vkernel context related to the current lwp now so we can
407 vkernel_lwp_exit(lp
);
412 * Release the user portion of address space. The exitbump prevents
413 * the vmspace from being completely eradicated (using holdcnt).
414 * This releases references to vnodes, which could cause I/O if the
415 * file has been unlinked. We need to do this early enough that
416 * we can still sleep.
418 * We can't free the entire vmspace as the kernel stack may be mapped
419 * within that space also.
421 * Processes sharing the same vmspace may exit in one order, and
422 * get cleaned up by vmspace_exit() in a different order. The
423 * last exiting process to reach this point releases as much of
424 * the environment as it can, and the last process cleaned up
425 * by vmspace_exit() (which decrements exitingcnt) cleans up the
428 * NOTE: Releasing p_token around this call is helpful if the
429 * vmspace had a huge RSS. Otherwise some other process
430 * trying to do an allproc or other scan (like 'ps') may
431 * stall for a long time.
433 lwkt_reltoken(&p
->p_token
);
435 lwkt_gettoken(&p
->p_token
);
437 if (SESS_LEADER(p
)) {
438 struct session
*sp
= p
->p_session
;
442 * We are the controlling process. Signal the
443 * foreground process group, drain the controlling
444 * terminal, and revoke access to the controlling
447 * NOTE: while waiting for the process group to exit
448 * it is possible that one of the processes in the
449 * group will revoke the tty, so the ttyclosesession()
450 * function will re-check sp->s_ttyvp.
452 if (sp
->s_ttyp
&& (sp
->s_ttyp
->t_session
== sp
)) {
453 if (sp
->s_ttyp
->t_pgrp
)
454 pgsignal(sp
->s_ttyp
->t_pgrp
, SIGHUP
, 1);
456 ttyclosesession(sp
, 1); /* also revoke */
459 * Release the tty. If someone has it open via
460 * /dev/tty then close it (since they no longer can
461 * once we've NULL'd it out).
463 ttyclosesession(sp
, 0);
466 * s_ttyp is not zero'd; we use this to indicate
467 * that the session once had a controlling terminal.
468 * (for logging and informational purposes)
473 fixjobc(p
, p
->p_pgrp
, 0);
474 (void)acct_process(p
);
480 ktrdestroy(&p
->p_tracenode
);
484 * Release reference to text vnode
486 if ((vtmp
= p
->p_textvp
) != NULL
) {
491 /* Release namecache handle to text file */
492 if (p
->p_textnch
.ncp
)
493 cache_drop(&p
->p_textnch
);
496 * We have to handle PPWAIT here or proc_move_allproc_zombie()
497 * will block on the PHOLD() the parent is doing.
499 * We are using the flag as an interlock so an atomic op is
500 * necessary to synchronize with the parent's cpu.
502 if (p
->p_flags
& P_PPWAIT
) {
503 if (p
->p_pptr
&& p
->p_pptr
->p_upmap
)
504 atomic_add_int(&p
->p_pptr
->p_upmap
->invfork
, -1);
505 atomic_clear_int(&p
->p_flags
, P_PPWAIT
);
510 * Move the process to the zombie list. This will block
511 * until the process p_lock count reaches 0. The process will
512 * not be reaped until TDF_EXITING is set by cpu_thread_exit(),
513 * which is called from cpu_proc_exit().
515 * Interlock against waiters using p_waitgen. We increment
516 * p_waitgen after completing the move of our process to the
519 * WARNING: pp becomes stale when we block, clear it now as a
522 proc_move_allproc_zombie(p
);
524 atomic_add_long(&pp
->p_waitgen
, 1);
528 * release controlled reaper for exit if we own it and return the
529 * remaining reaper (the one for us), which we will drop after we
532 reap
= reaper_exit(p
);
535 * Reparent all of this process's children to the init process or
536 * to the designated reaper. We must hold the reaper's p_token in
537 * order to safely mess with p_children.
539 * We already hold p->p_token (to remove the children from our list).
542 q
= LIST_FIRST(&p
->p_children
);
544 reproc
= reaper_get(reap
);
545 lwkt_gettoken(&reproc
->p_token
);
546 while ((q
= LIST_FIRST(&p
->p_children
)) != NULL
) {
548 lwkt_gettoken(&q
->p_token
);
549 if (q
!= LIST_FIRST(&p
->p_children
)) {
550 lwkt_reltoken(&q
->p_token
);
554 LIST_REMOVE(q
, p_sibling
);
555 LIST_INSERT_HEAD(&reproc
->p_children
, q
, p_sibling
);
557 q
->p_ppid
= reproc
->p_pid
;
558 q
->p_sigparent
= SIGCHLD
;
561 * Traced processes are killed
562 * since their existence means someone is screwing up.
564 if (q
->p_flags
& P_TRACED
) {
565 q
->p_flags
&= ~P_TRACED
;
568 lwkt_reltoken(&q
->p_token
);
571 lwkt_reltoken(&reproc
->p_token
);
576 * Save exit status and final rusage info. We no longer add
577 * child rusage info into self times, wait4() and kern_wait()
578 * handles it in order to properly support wait6().
580 calcru_proc(p
, &p
->p_ru
);
581 /*ruadd(&p->p_ru, &p->p_cru); REMOVED */
584 * notify interested parties of our demise.
586 KNOTE(&p
->p_klist
, NOTE_EXIT
);
589 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT
590 * flag set, or if the handler is set to SIG_IGN, notify the reaper
591 * instead (it will handle this situation).
593 * NOTE: The reaper can still be the parent process.
597 if (p
->p_pptr
->p_sigacts
->ps_flag
& (PS_NOCLDWAIT
| PS_CLDSIGIGN
)) {
599 reproc
= reaper_get(reap
);
600 proc_reparent(p
, reproc
);
608 * Signal (possibly new) parent.
612 if (p
->p_sigparent
&& pp
!= initproc
) {
613 int sig
= p
->p_sigparent
;
615 if (sig
!= SIGUSR1
&& sig
!= SIGCHLD
)
619 ksignal(pp
, SIGCHLD
);
621 p
->p_flags
&= ~P_TRACED
;
625 * cpu_exit is responsible for clearing curproc, since
626 * it is heavily integrated with the thread/switching sequence.
628 * Other substructures are freed from wait().
631 struct plimit
*rlimit
;
639 * Finally, call machine-dependent code to release as many of the
640 * lwp's resources as we can and halt execution of this thread.
642 * pp is a wild pointer now but still the correct wakeup() target.
643 * lwp_exit() only uses it to send the wakeup() signal to the likely
644 * parent. Any reparenting race that occurs will get a signal
645 * automatically and not be an issue.
651 * Eventually called by every exiting LWP
653 * p->p_token must be held. mplock may be held and will be released.
656 lwp_exit(int masterexit
, void *waddr
)
658 struct thread
*td
= curthread
;
659 struct lwp
*lp
= td
->td_lwp
;
660 struct proc
*p
= lp
->lwp_proc
;
664 * Release the current user process designation on the process so
665 * the userland scheduler can work in someone else.
667 p
->p_usched
->release_curproc(lp
);
670 * Destroy the per-thread shared page and remove from any pmaps
676 * lwp_exit() may be called without setting LWP_MP_WEXIT, so
677 * make sure it is set here.
679 ASSERT_LWKT_TOKEN_HELD(&p
->p_token
);
680 atomic_set_int(&lp
->lwp_mpflags
, LWP_MP_WEXIT
);
683 * Clean up any virtualization
686 vkernel_lwp_exit(lp
);
692 * Clean up select/poll support
694 kqueue_terminate(&lp
->lwp_kqueue
);
696 if (td
->td_linux_task
)
697 linux_task_drop_callback(td
);
698 if (masterexit
&& p
->p_linux_mm
)
699 linux_proc_drop_callback(p
);
702 * Clean up any syscall-cached ucred or rlimit.
705 crfree(td
->td_ucred
);
709 struct plimit
*rlimit
;
711 rlimit
= td
->td_limit
;
717 * Cleanup any cached descriptors for this thread
723 * Nobody actually wakes us when the lock
724 * count reaches zero, so just wait one tick.
726 while (lp
->lwp_lock
> 0)
727 tsleep(lp
, 0, "lwpexit", 1);
729 /* Hand down resource usage to our proc */
730 ruadd(&p
->p_ru
, &lp
->lwp_ru
);
733 * If we don't hold the process until the LWP is reaped wait*()
734 * may try to dispose of its vmspace before all the LWPs have
735 * actually terminated.
740 * Do any remaining work that might block on us. We should be
741 * coded such that further blocking is ok after decrementing
742 * p_nthreads but don't take the chance.
744 dsched_exit_thread(td
);
745 biosched_done(curthread
);
748 * We have to use the reaper for all the LWPs except the one doing
749 * the master exit. The LWP doing the master exit can just be
750 * left on p_lwps and the process reaper will deal with it
751 * synchronously, which is much faster.
753 * Wakeup anyone waiting on p_nthreads to drop to 1 or 0.
755 * The process is left held until the reaper calls lwp_dispose() on
756 * the lp (after calling lwp_wait()).
758 if (masterexit
== 0) {
761 lwp_rb_tree_RB_REMOVE(&p
->p_lwp_tree
, lp
);
763 if ((p
->p_flags
& P_MAYBETHREADED
) && p
->p_nthreads
<= 1)
765 lwkt_gettoken(&deadlwp_token
[cpu
]);
766 LIST_INSERT_HEAD(&deadlwp_list
[cpu
], lp
, u
.lwp_reap_entry
);
767 taskqueue_enqueue(taskqueue_thread
[cpu
], deadlwp_task
[cpu
]);
768 lwkt_reltoken(&deadlwp_token
[cpu
]);
771 if ((p
->p_flags
& P_MAYBETHREADED
) && p
->p_nthreads
<= 1)
776 * We no longer need p_token.
778 * Tell the userland scheduler that we are going away
780 lwkt_reltoken(&p
->p_token
);
781 p
->p_usched
->heuristic_exiting(lp
, p
);
784 * Issue late wakeups after releasing our token to give us a chance
785 * to deschedule and switch away before another cpu in a wait*()
786 * reaps us. This is done as late as possible to reduce contention.
789 wakeup(&p
->p_nthreads
);
797 * Wait until a lwp is completely dead. The final interlock in this drama
798 * is when TDF_EXITING is set in cpu_thread_exit() just before the final
801 * At the point TDF_EXITING is set a complete exit is accomplished when
802 * TDF_RUNNING and TDF_PREEMPT_LOCK are both clear. td_mpflags has two
803 * post-switch interlock flags that can be used to wait for the TDF_
806 * Returns non-zero on success, and zero if the caller needs to retry
810 lwp_wait(struct lwp
*lp
)
812 struct thread
*td
= lp
->lwp_thread
;
815 KKASSERT(lwkt_preempted_proc() != lp
);
818 * This bit of code uses the thread destruction interlock
819 * managed by lwkt_switch_return() to wait for the lwp's
820 * thread to completely disengage.
822 * It is possible for us to race another cpu core so we
823 * have to do this correctly.
826 mpflags
= td
->td_mpflags
;
828 if (mpflags
& TDF_MP_EXITSIG
)
830 tsleep_interlock(td
, 0);
831 if (atomic_cmpset_int(&td
->td_mpflags
, mpflags
,
832 mpflags
| TDF_MP_EXITWAIT
)) {
833 tsleep(td
, PINTERLOCKED
, "lwpxt", 0);
838 * We've already waited for the core exit but there can still
839 * be other refs from e.g. process scans and such.
841 if (lp
->lwp_lock
> 0) {
842 tsleep(lp
, 0, "lwpwait1", 1);
846 tsleep(td
, 0, "lwpwait2", 1);
851 * Now that we have the thread destruction interlock these flags
852 * really should already be cleaned up, keep a check for safety.
854 * We can't rip its stack out from under it until TDF_EXITING is
855 * set and both TDF_RUNNING and TDF_PREEMPT_LOCK are clear.
856 * TDF_PREEMPT_LOCK must be checked because TDF_RUNNING
857 * will be cleared temporarily if a thread gets preempted.
859 while ((td
->td_flags
& (TDF_RUNNING
|
862 TDF_EXITING
)) != TDF_EXITING
) {
863 tsleep(lp
, 0, "lwpwait3", 1);
867 KASSERT((td
->td_flags
& (TDF_RUNQ
|TDF_TSLEEPQ
)) == 0,
868 ("lwp_wait: td %p (%s) still on run or sleep queue",
874 * Release the resources associated with a lwp.
875 * The lwp must be completely dead.
878 lwp_dispose(struct lwp
*lp
)
880 struct thread
*td
= lp
->lwp_thread
;
882 KKASSERT(lwkt_preempted_proc() != lp
);
883 KKASSERT(lp
->lwp_lock
== 0);
884 KKASSERT(td
->td_refs
== 0);
885 KKASSERT((td
->td_flags
& (TDF_RUNNING
|
888 TDF_EXITING
)) == TDF_EXITING
);
895 lp
->lwp_thread
= NULL
;
896 lwkt_free_thread(td
);
902 sys_wait4(struct wait_args
*uap
)
904 struct __wrusage wrusage
;
911 options
= uap
->options
| WEXITED
| WTRAPPED
;
914 if (id
== WAIT_ANY
) {
916 } else if (id
== WAIT_MYPGRP
) {
918 id
= curproc
->p_pgid
;
926 error
= kern_wait(idtype
, id
, &status
, options
, &wrusage
,
927 NULL
, &uap
->sysmsg_result
);
929 if (error
== 0 && uap
->status
)
930 error
= copyout(&status
, uap
->status
, sizeof(*uap
->status
));
931 if (error
== 0 && uap
->rusage
) {
932 ruadd(&wrusage
.wru_self
, &wrusage
.wru_children
);
933 error
= copyout(&wrusage
.wru_self
, uap
->rusage
, sizeof(*uap
->rusage
));
939 sys_wait6(struct wait6_args
*uap
)
941 struct __wrusage wrusage
;
951 * NOTE: wait6() requires WEXITED and WTRAPPED to be specified if
954 options
= uap
->options
;
955 idtype
= uap
->idtype
;
957 infop
= uap
->info
? &info
: NULL
;
962 if (id
== WAIT_MYPGRP
) {
964 id
= curproc
->p_pgid
;
968 /* let kern_wait deal with the remainder */
972 error
= kern_wait(idtype
, id
, &status
, options
,
973 &wrusage
, infop
, &uap
->sysmsg_result
);
975 if (error
== 0 && uap
->status
)
976 error
= copyout(&status
, uap
->status
, sizeof(*uap
->status
));
977 if (error
== 0 && uap
->wrusage
)
978 error
= copyout(&wrusage
, uap
->wrusage
, sizeof(*uap
->wrusage
));
979 if (error
== 0 && uap
->info
)
980 error
= copyout(&info
, uap
->info
, sizeof(*uap
->info
));
985 * kernel wait*() system call support
988 kern_wait(idtype_t idtype
, id_t id
, int *status
, int options
,
989 struct __wrusage
*wrusage
, siginfo_t
*info
, int *res
)
991 struct thread
*td
= curthread
;
993 struct proc
*q
= td
->td_proc
;
1002 * Must not have extraneous options. Must have at least one
1005 if (options
&~ (WUNTRACED
|WNOHANG
|WCONTINUED
|WLINUXCLONE
|WSTOPPED
|
1006 WEXITED
|WTRAPPED
|WNOWAIT
)) {
1009 if ((options
& (WEXITED
| WUNTRACED
| WCONTINUED
| WTRAPPED
)) == 0) {
1014 * Protect the q->p_children list
1016 lwkt_gettoken(&q
->p_token
);
1019 * All sorts of things can change due to blocking so we have to loop
1020 * all the way back up here.
1022 * The problem is that if a process group is stopped and the parent
1023 * is doing a wait*(..., WUNTRACED, ...), it will see the STOP
1024 * of the child and then stop itself when it tries to return from the
1025 * system call. When the process group is resumed the parent will
1026 * then get the STOP status even though the child has now resumed
1027 * (a followup wait*() will get the CONT status).
1029 * Previously the CONT would overwrite the STOP because the tstop
1030 * was handled within tsleep(), and the parent would only see
1031 * the CONT when both are stopped and continued together. This little
1032 * two-line hack restores this effect.
1034 * No locks are held so we can safely block the process here.
1036 if (STOPLWP(q
, td
->td_lwp
))
1044 * NOTE: We don't want to break q's p_token in the loop for the
1045 * case where no children are found or we risk breaking the
1046 * interlock between child and parent.
1048 waitgen
= atomic_fetchadd_long(&q
->p_waitgen
, 0x80000000);
1049 LIST_FOREACH(p
, &q
->p_children
, p_sibling
) {
1051 * Skip children that another thread is already uninterruptably
1054 if (PWAITRES_PENDING(p
))
1058 * Filter, (p) will be held on fall-through. Try to optimize
1059 * this to avoid the atomic op until we are pretty sure we
1060 * want this process.
1067 if (p
->p_pid
!= (pid_t
)id
)
1072 if (p
->p_pgid
!= (pid_t
)id
)
1078 if (p
->p_session
&& p
->p_session
->s_sid
!= (pid_t
)id
) {
1085 if (p
->p_ucred
->cr_uid
!= (uid_t
)id
) {
1092 if (p
->p_ucred
->cr_gid
!= (gid_t
)id
) {
1099 if (p
->p_ucred
->cr_prison
&&
1100 p
->p_ucred
->cr_prison
->pr_id
!= (int)id
) {
1106 /* unsupported filter */
1109 /* (p) is held at this point */
1112 * This special case handles a kthread spawned by linux_clone
1113 * (see linux_misc.c). The linux_wait4 and linux_waitpid
1114 * functions need to be able to distinguish between waiting
1115 * on a process and waiting on a thread. It is a thread if
1116 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
1117 * signifies we want to wait for threads and not processes.
1119 if ((p
->p_sigparent
!= SIGCHLD
) ^
1120 ((options
& WLINUXCLONE
) != 0)) {
1126 if (p
->p_stat
== SZOMB
&& (options
& WEXITED
)) {
1128 * We may go into SZOMB with threads still present.
1129 * We must wait for them to exit before we can reap
1130 * the master thread, otherwise we may race reaping
1131 * non-master threads.
1133 * Only this routine can remove a process from
1134 * the zombie list and destroy it.
1136 * This function will fail after sleeping if another
1137 * thread owns the zombie lock. This function will
1138 * fail immediately or after sleeping if another
1139 * thread owns or obtains ownership of the reap via
1146 lwkt_gettoken(&p
->p_token
);
1147 if (p
->p_pptr
!= q
) {
1148 lwkt_reltoken(&p
->p_token
);
1155 * We are the reaper, from this point on the reap
1156 * cannot be aborted.
1159 while (p
->p_nthreads
> 0) {
1160 tsleep(&p
->p_nthreads
, 0, "lwpzomb", hz
);
1164 * Reap any LWPs left in p->p_lwps. This is usually
1165 * just the last LWP. This must be done before
1166 * we loop on p_lock since the lwps hold a ref on
1167 * it as a vmspace interlock.
1169 * Once that is accomplished p_nthreads had better
1172 while ((lp
= RB_ROOT(&p
->p_lwp_tree
)) != NULL
) {
1174 * Make sure no one is using this lwp, before
1175 * it is removed from the tree. If we didn't
1176 * wait it here, lwp tree iteration with
1177 * blocking operation would be broken.
1179 while (lp
->lwp_lock
> 0)
1180 tsleep(lp
, 0, "zomblwp", 1);
1181 lwp_rb_tree_RB_REMOVE(&p
->p_lwp_tree
, lp
);
1184 KKASSERT(p
->p_nthreads
== 0);
1187 * Don't do anything really bad until all references
1188 * to the process go away. This may include other
1189 * LWPs which are still in the process of being
1190 * reaped. We can't just pull the rug out from under
1191 * them because they may still be using the VM space.
1193 * Certain kernel facilities such as /proc will also
1194 * put a hold on the process for short periods of
1197 PRELE(p
); /* from top of loop */
1198 PSTALL(p
, "reap3", 1); /* 1 ref (for PZOMBHOLD) */
1200 /* Take care of our return values. */
1203 *status
= p
->p_xstat
;
1204 wrusage
->wru_self
= p
->p_ru
;
1205 wrusage
->wru_children
= p
->p_cru
;
1208 bzero(info
, sizeof(*info
));
1210 info
->si_signo
= SIGCHLD
;
1211 if (WIFEXITED(p
->p_xstat
)) {
1212 info
->si_code
= CLD_EXITED
;
1214 WEXITSTATUS(p
->p_xstat
);
1216 info
->si_code
= CLD_KILLED
;
1217 info
->si_status
= WTERMSIG(p
->p_xstat
);
1219 info
->si_pid
= p
->p_pid
;
1220 info
->si_uid
= p
->p_ucred
->cr_uid
;
1224 * WNOWAIT shortcuts to done here, leaving the
1225 * child on the zombie list.
1227 if (options
& WNOWAIT
) {
1228 lwkt_reltoken(&p
->p_token
);
1235 * If we got the child via a ptrace 'attach',
1236 * we need to give it back to the old parent.
1238 if (p
->p_oppid
&& (t
= pfind(p
->p_oppid
)) != NULL
) {
1240 proc_reparent(p
, t
);
1241 ksignal(t
, SIGCHLD
);
1244 lwkt_reltoken(&p
->p_token
);
1251 * Unlink the proc from its process group so that
1252 * the following operations won't lead to an
1253 * inconsistent state for processes running down
1256 proc_remove_zombie(p
);
1258 lwkt_reltoken(&p
->p_token
);
1262 ruadd(&q
->p_cru
, &p
->p_ru
);
1263 ruadd(&q
->p_cru
, &p
->p_cru
);
1266 * Decrement the count of procs running with this uid.
1268 chgproccnt(p
->p_ucred
->cr_ruidinfo
, -1, 0);
1271 * Free up credentials. p_spin is required to
1272 * avoid races against allproc scans.
1274 spin_lock(&p
->p_spin
);
1277 spin_unlock(&p
->p_spin
);
1281 * Remove unused arguments
1285 if (pa
&& refcount_release(&pa
->ar_ref
)) {
1291 p
->p_sigacts
= NULL
;
1292 if (ps
&& refcount_release(&ps
->ps_refcnt
)) {
1293 kfree(ps
, M_SUBPROC
);
1298 * Our exitingcount was incremented when the process
1299 * became a zombie, now that the process has been
1300 * removed from (almost) all lists we should be able
1301 * to safely destroy its vmspace. Wait for any current
1302 * holders to go away (so the vmspace remains stable),
1305 * NOTE: Releasing the parent process (q) p_token
1306 * across the vmspace_exitfree() call is
1307 * important here to reduce stalls on
1308 * interactions with (q) (such as
1309 * fork/exec/wait or 'ps').
1311 PSTALL(p
, "reap4", 1);
1312 lwkt_reltoken(&q
->p_token
);
1313 vmspace_exitfree(p
);
1314 lwkt_gettoken(&q
->p_token
);
1315 PSTALL(p
, "reap5", 1);
1318 * NOTE: We have to officially release ZOMB in order
1319 * to ensure that a racing thread in kern_wait()
1320 * which blocked on ZOMB is woken up.
1323 kfree(p
->p_uidpcpu
, M_SUBPROC
);
1325 atomic_add_int(&nprocs
, -1);
1331 * Process has not yet exited
1333 if ((p
->p_stat
== SSTOP
|| p
->p_stat
== SCORE
) &&
1334 (p
->p_flags
& P_WAITED
) == 0 &&
1335 (((p
->p_flags
& P_TRACED
) && (options
& WTRAPPED
)) ||
1336 (options
& WSTOPPED
))) {
1337 lwkt_gettoken(&p
->p_token
);
1338 if (p
->p_pptr
!= q
) {
1339 lwkt_reltoken(&p
->p_token
);
1343 if ((p
->p_stat
!= SSTOP
&& p
->p_stat
!= SCORE
) ||
1344 (p
->p_flags
& P_WAITED
) != 0 ||
1345 ((p
->p_flags
& P_TRACED
) == 0 &&
1346 (options
& WUNTRACED
) == 0)) {
1347 lwkt_reltoken(&p
->p_token
);
1353 * Don't set P_WAITED if WNOWAIT specified, leaving
1354 * the process in a waitable state.
1356 if ((options
& WNOWAIT
) == 0)
1357 p
->p_flags
|= P_WAITED
;
1360 *status
= W_STOPCODE(p
->p_xstat
);
1361 /* Zero rusage so we get something consistent. */
1362 bzero(wrusage
, sizeof(*wrusage
));
1365 bzero(info
, sizeof(*info
));
1366 if (p
->p_flags
& P_TRACED
)
1367 info
->si_code
= CLD_TRAPPED
;
1369 info
->si_code
= CLD_STOPPED
;
1370 info
->si_status
= WSTOPSIG(p
->p_xstat
);
1372 lwkt_reltoken(&p
->p_token
);
1376 if ((options
& WCONTINUED
) && (p
->p_flags
& P_CONTINUED
)) {
1377 lwkt_gettoken(&p
->p_token
);
1378 if (p
->p_pptr
!= q
) {
1379 lwkt_reltoken(&p
->p_token
);
1383 if ((p
->p_flags
& P_CONTINUED
) == 0) {
1384 lwkt_reltoken(&p
->p_token
);
1392 * Don't set P_WAITED if WNOWAIT specified, leaving
1393 * the process in a waitable state.
1395 if ((options
& WNOWAIT
) == 0)
1396 p
->p_flags
&= ~P_CONTINUED
;
1401 bzero(info
, sizeof(*info
));
1402 info
->si_code
= CLD_CONTINUED
;
1403 info
->si_status
= WSTOPSIG(p
->p_xstat
);
1405 lwkt_reltoken(&p
->p_token
);
1415 if (options
& WNOHANG
) {
1422 * Wait for signal - interlocked using q->p_waitgen.
1425 while ((waitgen
& 0x7FFFFFFF) == (q
->p_waitgen
& 0x7FFFFFFF)) {
1426 tsleep_interlock(q
, PCATCH
);
1427 waitgen
= atomic_fetchadd_long(&q
->p_waitgen
, 0x80000000);
1428 if ((waitgen
& 0x7FFFFFFF) == (q
->p_waitgen
& 0x7FFFFFFF)) {
1429 error
= tsleep(q
, PCATCH
| PINTERLOCKED
, "wait", 0);
1435 lwkt_reltoken(&q
->p_token
);
1442 * Change child's parent process to parent.
1444 * p_children/p_sibling requires the parent's token, and
1445 * changing pptr requires the child's token, so we have to
1446 * get three tokens to do this operation. We also need to
1447 * hold pointers that might get ripped out from under us to
1448 * preserve structural integrity.
1450 * It is possible to race another reparent or disconnect or other
1451 * similar operation. We must retry when this situation occurs.
1452 * Once we successfully reparent the process we no longer care
1456 proc_reparent(struct proc
*child
, struct proc
*parent
)
1461 while ((opp
= child
->p_pptr
) != parent
) {
1463 lwkt_gettoken(&opp
->p_token
);
1464 lwkt_gettoken(&child
->p_token
);
1465 lwkt_gettoken(&parent
->p_token
);
1466 if (child
->p_pptr
!= opp
) {
1467 lwkt_reltoken(&parent
->p_token
);
1468 lwkt_reltoken(&child
->p_token
);
1469 lwkt_reltoken(&opp
->p_token
);
1473 LIST_REMOVE(child
, p_sibling
);
1474 LIST_INSERT_HEAD(&parent
->p_children
, child
, p_sibling
);
1475 child
->p_pptr
= parent
;
1476 child
->p_ppid
= parent
->p_pid
;
1477 lwkt_reltoken(&parent
->p_token
);
1478 lwkt_reltoken(&child
->p_token
);
1479 lwkt_reltoken(&opp
->p_token
);
1480 if (LIST_EMPTY(&opp
->p_children
))
1489 * The next two functions are to handle adding/deleting items on the
1493 * Take the arguments given and put them onto the exit callout list,
1494 * However first make sure that it's not already there.
1495 * returns 0 on success.
1499 at_exit(exitlist_fn function
)
1501 struct exitlist
*ep
;
1504 /* Be noisy if the programmer has lost track of things */
1505 if (rm_at_exit(function
))
1506 kprintf("WARNING: exit callout entry (%p) already present\n",
1509 ep
= kmalloc(sizeof(*ep
), M_ATEXIT
, M_NOWAIT
);
1512 ep
->function
= function
;
1513 TAILQ_INSERT_TAIL(&exit_list
, ep
, next
);
1518 * Scan the exit callout list for the given item and remove it.
1519 * Returns the number of items removed (0 or 1)
1522 rm_at_exit(exitlist_fn function
)
1524 struct exitlist
*ep
;
1526 TAILQ_FOREACH(ep
, &exit_list
, next
) {
1527 if (ep
->function
== function
) {
1528 TAILQ_REMOVE(&exit_list
, ep
, next
);
1529 kfree(ep
, M_ATEXIT
);
1537 * LWP reaper related code.
1540 reaplwps(void *context
, int dummy
)
1542 struct lwplist
*lwplist
= context
;
1546 lwkt_gettoken(&deadlwp_token
[cpu
]);
1547 while ((lp
= LIST_FIRST(lwplist
))) {
1548 LIST_REMOVE(lp
, u
.lwp_reap_entry
);
1551 lwkt_reltoken(&deadlwp_token
[cpu
]);
1555 reaplwp(struct lwp
*lp
)
1557 while (lwp_wait(lp
) == 0)
1567 for (cpu
= 0; cpu
< ncpus
; cpu
++) {
1568 lwkt_token_init(&deadlwp_token
[cpu
], "deadlwpl");
1569 LIST_INIT(&deadlwp_list
[cpu
]);
1570 deadlwp_task
[cpu
] = kmalloc(sizeof(*deadlwp_task
[cpu
]),
1571 M_DEVBUF
, M_WAITOK
);
1572 TASK_INIT(deadlwp_task
[cpu
], 0, reaplwps
, &deadlwp_list
[cpu
]);
1576 SYSINIT(deadlwpinit
, SI_SUB_CONFIGURE
, SI_ORDER_ANY
, deadlwp_init
, NULL
);