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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_compat.h"
39 #include "opt_ktrace.h"
41 #include <sys/param.h>
42 #include <sys/systm.h>
43 #include <sys/sysproto.h>
44 #include <sys/kernel.h>
45 #include <sys/malloc.h>
47 #include <sys/ktrace.h>
48 #include <sys/pioctl.h>
51 #include <sys/vnode.h>
52 #include <sys/resourcevar.h>
53 #include <sys/signalvar.h>
54 #include <sys/taskqueue.h>
55 #include <sys/ptrace.h>
56 #include <sys/acct.h> /* for acct_process() function prototype */
57 #include <sys/filedesc.h>
61 #include <sys/kern_syscall.h>
62 #include <sys/unistd.h>
63 #include <sys/eventhandler.h>
64 #include <sys/dsched.h>
67 #include <vm/vm_param.h>
70 #include <vm/vm_map.h>
71 #include <vm/vm_extern.h>
74 #include <sys/refcount.h>
75 #include <sys/thread2.h>
76 #include <sys/sysref2.h>
77 #include <sys/mplock2.h>
79 #include <machine/vmm.h>
81 static void reaplwps(void *context, int dummy);
82 static void reaplwp(struct lwp *lp);
83 static void killlwps(struct lwp *lp);
85 static MALLOC_DEFINE(M_ATEXIT, "atexit", "atexit callback");
88 * callout list for things to do at exit time
92 TAILQ_ENTRY(exitlist) next;
95 TAILQ_HEAD(exit_list_head, exitlist);
96 static struct exit_list_head exit_list = TAILQ_HEAD_INITIALIZER(exit_list);
101 static struct task *deadlwp_task[MAXCPU];
102 static struct lwplist deadlwp_list[MAXCPU];
103 static struct lwkt_token deadlwp_token[MAXCPU];
109 * SYS_EXIT_ARGS(int rval)
112 sys_exit(struct exit_args *uap)
114 exit1(W_EXITCODE(uap->rval, 0));
120 * Death of a lwp or process with optional bells and whistles.
125 sys_extexit(struct extexit_args *uap)
127 struct proc *p = curproc;
131 action = EXTEXIT_ACTION(uap->how);
132 who = EXTEXIT_WHO(uap->how);
134 /* Check parameters before we might perform some action */
147 error = copyout(&uap->status, uap->addr, sizeof(uap->status));
155 lwkt_gettoken(&p->p_token);
160 * Be sure only to perform a simple lwp exit if there is at
161 * least one more lwp in the proc, which will call exit1()
162 * later, otherwise the proc will be an UNDEAD and not even a
165 if (p->p_nthreads > 1) {
166 lwp_exit(0); /* called w/ p_token held */
169 /* else last lwp in proc: do the real thing */
171 default: /* to help gcc */
173 lwkt_reltoken(&p->p_token);
174 exit1(W_EXITCODE(uap->status, 0));
179 lwkt_reltoken(&p->p_token); /* safety */
183 * Kill all lwps associated with the current process except the
184 * current lwp. Return an error if we race another thread trying to
185 * do the same thing and lose the race.
187 * If forexec is non-zero the current thread and process flags are
188 * cleaned up so they can be reused.
190 * Caller must hold curproc->p_token
193 killalllwps(int forexec)
195 struct lwp *lp = curthread->td_lwp;
196 struct proc *p = lp->lwp_proc;
199 * Interlock against P_WEXIT. Only one of the process's thread
200 * is allowed to do the master exit.
202 if (p->p_flags & P_WEXIT)
204 p->p_flags |= P_WEXIT;
207 * Interlock with LWP_MP_WEXIT and kill any remaining LWPs
209 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT);
210 if (p->p_nthreads > 1)
214 * If doing this for an exec, clean up the remaining thread
215 * (us) for continuing operation after all the other threads
219 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_WEXIT);
220 p->p_flags &= ~P_WEXIT;
226 * Kill all LWPs except the current one. Do not try to signal
227 * LWPs which have exited on their own or have already been
231 killlwps(struct lwp *lp)
233 struct proc *p = lp->lwp_proc;
237 * Kill the remaining LWPs. We must send the signal before setting
238 * LWP_MP_WEXIT. The setting of WEXIT is optional but helps reduce
239 * races. tlp must be held across the call as it might block and
240 * allow the target lwp to rip itself out from under our loop.
242 FOREACH_LWP_IN_PROC(tlp, p) {
244 lwkt_gettoken(&tlp->lwp_token);
245 if ((tlp->lwp_mpflags & LWP_MP_WEXIT) == 0) {
246 lwpsignal(p, tlp, SIGKILL);
247 atomic_set_int(&tlp->lwp_mpflags, LWP_MP_WEXIT);
249 lwkt_reltoken(&tlp->lwp_token);
254 * Wait for everything to clear out.
256 while (p->p_nthreads > 1) {
257 tsleep(&p->p_nthreads, 0, "killlwps", 0);
262 * Exit: deallocate address space and other resources, change proc state
263 * to zombie, and unlink proc from allproc and parent's lists. Save exit
264 * status and rusage for wait(). Check for child processes and orphan them.
269 struct thread *td = curthread;
270 struct proc *p = td->td_proc;
271 struct lwp *lp = td->td_lwp;
278 lwkt_gettoken(&p->p_token);
281 kprintf("init died (signal %d, exit %d)\n",
282 WTERMSIG(rv), WEXITSTATUS(rv));
283 panic("Going nowhere without my init!");
285 varsymset_clean(&p->p_varsymset);
286 lockuninit(&p->p_varsymset.vx_lock);
289 * Kill all lwps associated with the current process, return an
290 * error if we race another thread trying to do the same thing
293 error = killalllwps(0);
299 /* are we a task leader? */
300 if (p == p->p_leader) {
301 struct kill_args killArgs;
302 killArgs.signum = SIGKILL;
305 killArgs.pid = q->p_pid;
307 * The interface for kill is better
308 * than the internal signal
314 tsleep((caddr_t)p, 0, "exit1", 0);
320 STOPEVENT(p, S_EXIT, rv);
321 p->p_flags |= P_POSTEXIT; /* stop procfs stepping */
324 * Check if any loadable modules need anything done at process exit.
325 * e.g. SYSV IPC stuff
326 * XXX what if one of these generates an error?
329 EVENTHANDLER_INVOKE(process_exit, p);
332 * XXX: imho, the eventhandler stuff is much cleaner than this.
333 * Maybe we should move everything to use eventhandler.
335 TAILQ_FOREACH(ep, &exit_list, next)
338 if (p->p_flags & P_PROFIL)
341 SIGEMPTYSET(p->p_siglist);
342 SIGEMPTYSET(lp->lwp_siglist);
343 if (timevalisset(&p->p_realtimer.it_value))
344 callout_stop_sync(&p->p_ithandle);
347 * Reset any sigio structures pointing to us as a result of
348 * F_SETOWN with our pid.
350 funsetownlst(&p->p_sigiolst);
353 * Close open files and release open-file table.
358 if(p->p_leader->p_peers) {
360 while(q->p_peers != p)
362 q->p_peers = p->p_peers;
363 wakeup((caddr_t)p->p_leader);
367 * XXX Shutdown SYSV semaphores
371 KKASSERT(p->p_numposixlocks == 0);
373 /* The next two chunks should probably be moved to vmspace_exit. */
377 * Clean up data related to virtual kernel operation. Clean up
378 * any vkernel context related to the current lwp now so we can
382 vkernel_lwp_exit(lp);
387 * Release user portion of address space.
388 * This releases references to vnodes,
389 * which could cause I/O if the file has been unlinked.
390 * Need to do this early enough that we can still sleep.
391 * Can't free the entire vmspace as the kernel stack
392 * may be mapped within that space also.
394 * Processes sharing the same vmspace may exit in one order, and
395 * get cleaned up by vmspace_exit() in a different order. The
396 * last exiting process to reach this point releases as much of
397 * the environment as it can, and the last process cleaned up
398 * by vmspace_exit() (which decrements exitingcnt) cleans up the
401 vmspace_exitbump(vm);
402 sysref_put(&vm->vm_sysref);
404 if (SESS_LEADER(p)) {
405 struct session *sp = p->p_session;
409 * We are the controlling process. Signal the
410 * foreground process group, drain the controlling
411 * terminal, and revoke access to the controlling
414 * NOTE: while waiting for the process group to exit
415 * it is possible that one of the processes in the
416 * group will revoke the tty, so the ttyclosesession()
417 * function will re-check sp->s_ttyvp.
419 if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) {
420 if (sp->s_ttyp->t_pgrp)
421 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1);
423 ttyclosesession(sp, 1); /* also revoke */
426 * Release the tty. If someone has it open via
427 * /dev/tty then close it (since they no longer can
428 * once we've NULL'd it out).
430 ttyclosesession(sp, 0);
433 * s_ttyp is not zero'd; we use this to indicate
434 * that the session once had a controlling terminal.
435 * (for logging and informational purposes)
440 fixjobc(p, p->p_pgrp, 0);
441 (void)acct_process(p);
447 ktrdestroy(&p->p_tracenode);
451 * Release reference to text vnode
453 if ((vtmp = p->p_textvp) != NULL) {
458 /* Release namecache handle to text file */
459 if (p->p_textnch.ncp)
460 cache_drop(&p->p_textnch);
463 * We have to handle PPWAIT here or proc_move_allproc_zombie()
464 * will block on the PHOLD() the parent is doing.
466 if (p->p_flags & P_PPWAIT) {
467 p->p_flags &= ~P_PPWAIT;
472 * Move the process to the zombie list. This will block
473 * until the process p_lock count reaches 0. The process will
474 * not be reaped until TDF_EXITING is set by cpu_thread_exit(),
475 * which is called from cpu_proc_exit().
477 proc_move_allproc_zombie(p);
480 * Reparent all of this process's children to the init process.
481 * We must hold initproc->p_token in order to mess with
482 * initproc->p_children. We already hold p->p_token (to remove
483 * the children from our list).
485 q = LIST_FIRST(&p->p_children);
487 lwkt_gettoken(&initproc->p_token);
488 while ((q = LIST_FIRST(&p->p_children)) != NULL) {
490 lwkt_gettoken(&q->p_token);
491 if (q != LIST_FIRST(&p->p_children)) {
492 lwkt_reltoken(&q->p_token);
496 LIST_REMOVE(q, p_sibling);
497 LIST_INSERT_HEAD(&initproc->p_children, q, p_sibling);
498 q->p_pptr = initproc;
499 q->p_sigparent = SIGCHLD;
502 * Traced processes are killed
503 * since their existence means someone is screwing up.
505 if (q->p_flags & P_TRACED) {
506 q->p_flags &= ~P_TRACED;
509 lwkt_reltoken(&q->p_token);
512 lwkt_reltoken(&initproc->p_token);
517 * Save exit status and final rusage info, adding in child rusage
518 * info and self times.
520 calcru_proc(p, &p->p_ru);
521 ruadd(&p->p_ru, &p->p_cru);
524 * notify interested parties of our demise.
526 KNOTE(&p->p_klist, NOTE_EXIT);
529 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT
530 * flag set, or if the handler is set to SIG_IGN, notify process 1
531 * instead (and hope it will handle this situation).
533 if (p->p_pptr->p_sigacts->ps_flag & (PS_NOCLDWAIT | PS_CLDSIGIGN)) {
534 proc_reparent(p, initproc);
537 /* lwkt_gettoken(&proc_token); */
540 if (p->p_sigparent && q != initproc) {
541 ksignal(q, p->p_sigparent);
546 p->p_flags &= ~P_TRACED;
550 /* lwkt_reltoken(&proc_token); */
551 /* NOTE: p->p_pptr can get ripped out */
553 * cpu_exit is responsible for clearing curproc, since
554 * it is heavily integrated with the thread/switching sequence.
556 * Other substructures are freed from wait().
561 * Finally, call machine-dependent code to release as many of the
562 * lwp's resources as we can and halt execution of this thread.
568 * Eventually called by every exiting LWP
570 * p->p_token must be held. mplock may be held and will be released.
573 lwp_exit(int masterexit)
575 struct thread *td = curthread;
576 struct lwp *lp = td->td_lwp;
577 struct proc *p = lp->lwp_proc;
581 * Release the current user process designation on the process so
582 * the userland scheduler can work in someone else.
584 p->p_usched->release_curproc(lp);
587 * lwp_exit() may be called without setting LWP_MP_WEXIT, so
588 * make sure it is set here.
590 ASSERT_LWKT_TOKEN_HELD(&p->p_token);
591 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT);
594 * Clean up any virtualization
597 vkernel_lwp_exit(lp);
603 * Clean up select/poll support
605 kqueue_terminate(&lp->lwp_kqueue);
608 * Clean up any syscall-cached ucred
611 crfree(td->td_ucred);
616 * Nobody actually wakes us when the lock
617 * count reaches zero, so just wait one tick.
619 while (lp->lwp_lock > 0)
620 tsleep(lp, 0, "lwpexit", 1);
622 /* Hand down resource usage to our proc */
623 ruadd(&p->p_ru, &lp->lwp_ru);
626 * If we don't hold the process until the LWP is reaped wait*()
627 * may try to dispose of its vmspace before all the LWPs have
628 * actually terminated.
633 * Do any remaining work that might block on us. We should be
634 * coded such that further blocking is ok after decrementing
635 * p_nthreads but don't take the chance.
637 dsched_exit_thread(td);
638 biosched_done(curthread);
641 * We have to use the reaper for all the LWPs except the one doing
642 * the master exit. The LWP doing the master exit can just be
643 * left on p_lwps and the process reaper will deal with it
644 * synchronously, which is much faster.
646 * Wakeup anyone waiting on p_nthreads to drop to 1 or 0.
648 * The process is left held until the reaper calls lwp_dispose() on
649 * the lp (after calling lwp_wait()).
651 if (masterexit == 0) {
654 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp);
656 if (p->p_nthreads <= 1)
658 lwkt_gettoken(&deadlwp_token[cpu]);
659 LIST_INSERT_HEAD(&deadlwp_list[cpu], lp, u.lwp_reap_entry);
660 taskqueue_enqueue(taskqueue_thread[cpu], deadlwp_task[cpu]);
661 lwkt_reltoken(&deadlwp_token[cpu]);
664 if (p->p_nthreads <= 1)
669 * Release p_token. Issue the wakeup() on p_nthreads if necessary,
670 * as late as possible to give us a chance to actually deschedule and
671 * switch away before another cpu core hits reaplwp().
673 lwkt_reltoken(&p->p_token);
675 wakeup(&p->p_nthreads);
678 * Tell the userland scheduler that we are going away
680 p->p_usched->heuristic_exiting(lp, p);
686 * Wait until a lwp is completely dead. The final interlock in this drama
687 * is when TDF_EXITING is set in cpu_thread_exit() just before the final
690 * At the point TDF_EXITING is set a complete exit is accomplished when
691 * TDF_RUNNING and TDF_PREEMPT_LOCK are both clear. td_mpflags has two
692 * post-switch interlock flags that can be used to wait for the TDF_
695 * Returns non-zero on success, and zero if the caller needs to retry
699 lwp_wait(struct lwp *lp)
701 struct thread *td = lp->lwp_thread;
704 KKASSERT(lwkt_preempted_proc() != lp);
707 * This bit of code uses the thread destruction interlock
708 * managed by lwkt_switch_return() to wait for the lwp's
709 * thread to completely disengage.
711 * It is possible for us to race another cpu core so we
712 * have to do this correctly.
715 mpflags = td->td_mpflags;
717 if (mpflags & TDF_MP_EXITSIG)
719 tsleep_interlock(td, 0);
720 if (atomic_cmpset_int(&td->td_mpflags, mpflags,
721 mpflags | TDF_MP_EXITWAIT)) {
722 tsleep(td, PINTERLOCKED, "lwpxt", 0);
727 * We've already waited for the core exit but there can still
728 * be other refs from e.g. process scans and such.
730 if (lp->lwp_lock > 0) {
731 tsleep(lp, 0, "lwpwait1", 1);
735 tsleep(td, 0, "lwpwait2", 1);
740 * Now that we have the thread destruction interlock these flags
741 * really should already be cleaned up, keep a check for safety.
743 * We can't rip its stack out from under it until TDF_EXITING is
744 * set and both TDF_RUNNING and TDF_PREEMPT_LOCK are clear.
745 * TDF_PREEMPT_LOCK must be checked because TDF_RUNNING
746 * will be cleared temporarily if a thread gets preempted.
748 while ((td->td_flags & (TDF_RUNNING |
750 TDF_EXITING)) != TDF_EXITING) {
751 tsleep(lp, 0, "lwpwait3", 1);
755 KASSERT((td->td_flags & (TDF_RUNQ|TDF_TSLEEPQ)) == 0,
756 ("lwp_wait: td %p (%s) still on run or sleep queue",
762 * Release the resources associated with a lwp.
763 * The lwp must be completely dead.
766 lwp_dispose(struct lwp *lp)
768 struct thread *td = lp->lwp_thread;
770 KKASSERT(lwkt_preempted_proc() != lp);
771 KKASSERT(td->td_refs == 0);
772 KKASSERT((td->td_flags & (TDF_RUNNING |
774 TDF_EXITING)) == TDF_EXITING);
781 lp->lwp_thread = NULL;
782 lwkt_free_thread(td);
791 sys_wait4(struct wait_args *uap)
793 struct rusage rusage;
796 error = kern_wait(uap->pid, (uap->status ? &status : NULL),
797 uap->options, (uap->rusage ? &rusage : NULL),
798 &uap->sysmsg_result);
800 if (error == 0 && uap->status)
801 error = copyout(&status, uap->status, sizeof(*uap->status));
802 if (error == 0 && uap->rusage)
803 error = copyout(&rusage, uap->rusage, sizeof(*uap->rusage));
810 * wait_args(int pid, int *status, int options, struct rusage *rusage)
815 kern_wait(pid_t pid, int *status, int options, struct rusage *rusage, int *res)
817 struct thread *td = curthread;
819 struct proc *q = td->td_proc;
827 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WLINUXCLONE))
830 lwkt_gettoken(&q->p_token);
833 * All sorts of things can change due to blocking so we have to loop
834 * all the way back up here.
836 * The problem is that if a process group is stopped and the parent
837 * is doing a wait*(..., WUNTRACED, ...), it will see the STOP
838 * of the child and then stop itself when it tries to return from the
839 * system call. When the process group is resumed the parent will
840 * then get the STOP status even though the child has now resumed
841 * (a followup wait*() will get the CONT status).
843 * Previously the CONT would overwrite the STOP because the tstop
844 * was handled within tsleep(), and the parent would only see
845 * the CONT when both are stopped and continued together. This little
846 * two-line hack restores this effect.
848 while (q->p_stat == SSTOP)
856 * NOTE: We don't want to break q's p_token in the loop for the
857 * case where no children are found or we risk breaking the
858 * interlock between child and parent.
860 LIST_FOREACH(p, &q->p_children, p_sibling) {
861 if (pid != WAIT_ANY &&
862 p->p_pid != pid && p->p_pgid != -pid) {
867 * This special case handles a kthread spawned by linux_clone
868 * (see linux_misc.c). The linux_wait4 and linux_waitpid
869 * functions need to be able to distinguish between waiting
870 * on a process and waiting on a thread. It is a thread if
871 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
872 * signifies we want to wait for threads and not processes.
874 if ((p->p_sigparent != SIGCHLD) ^
875 ((options & WLINUXCLONE) != 0)) {
880 if (p->p_stat == SZOMB) {
882 * We may go into SZOMB with threads still present.
883 * We must wait for them to exit before we can reap
884 * the master thread, otherwise we may race reaping
885 * non-master threads.
887 * Only this routine can remove a process from
888 * the zombie list and destroy it, use PACQUIREZOMB()
889 * to serialize us and loop if it blocks (interlocked
890 * by the parent's q->p_token).
892 * WARNING! (p) can be invalid when PHOLDZOMB(p)
893 * returns non-zero. Be sure not to
898 lwkt_gettoken(&p->p_token);
899 if (p->p_pptr != q) {
900 lwkt_reltoken(&p->p_token);
904 while (p->p_nthreads > 0) {
905 tsleep(&p->p_nthreads, 0, "lwpzomb", hz);
909 * Reap any LWPs left in p->p_lwps. This is usually
910 * just the last LWP. This must be done before
911 * we loop on p_lock since the lwps hold a ref on
912 * it as a vmspace interlock.
914 * Once that is accomplished p_nthreads had better
917 while ((lp = RB_ROOT(&p->p_lwp_tree)) != NULL) {
918 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp);
921 KKASSERT(p->p_nthreads == 0);
924 * Don't do anything really bad until all references
925 * to the process go away. This may include other
926 * LWPs which are still in the process of being
927 * reaped. We can't just pull the rug out from under
928 * them because they may still be using the VM space.
930 * Certain kernel facilities such as /proc will also
931 * put a hold on the process for short periods of
935 PSTALL(p, "reap3", 0);
937 /* Take care of our return values. */
941 *status = p->p_xstat;
945 * If we got the child via a ptrace 'attach',
946 * we need to give it back to the old parent.
948 if (p->p_oppid && (t = pfind(p->p_oppid)) != NULL) {
956 lwkt_reltoken(&p->p_token);
962 * Unlink the proc from its process group so that
963 * the following operations won't lead to an
964 * inconsistent state for processes running down
967 proc_remove_zombie(p);
968 lwkt_reltoken(&p->p_token);
972 ruadd(&q->p_cru, &p->p_ru);
975 * Decrement the count of procs running with this uid.
977 chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
980 * Free up credentials.
986 * Remove unused arguments
990 if (pa && refcount_release(&pa->ar_ref)) {
997 if (ps && refcount_release(&ps->ps_refcnt)) {
998 kfree(ps, M_SUBPROC);
1003 * Our exitingcount was incremented when the process
1004 * became a zombie, now that the process has been
1005 * removed from (almost) all lists we should be able
1006 * to safely destroy its vmspace. Wait for any current
1007 * holders to go away (so the vmspace remains stable),
1010 PSTALL(p, "reap4", 0);
1011 vmspace_exitfree(p);
1012 PSTALL(p, "reap5", 0);
1015 * NOTE: We have to officially release ZOMB in order
1016 * to ensure that a racing thread in kern_wait()
1017 * which blocked on ZOMB is woken up.
1022 atomic_add_int(&nprocs, -1);
1026 if (p->p_stat == SSTOP && (p->p_flags & P_WAITED) == 0 &&
1027 ((p->p_flags & P_TRACED) || (options & WUNTRACED))) {
1029 lwkt_gettoken(&p->p_token);
1030 if (p->p_pptr != q) {
1031 lwkt_reltoken(&p->p_token);
1035 if (p->p_stat != SSTOP ||
1036 (p->p_flags & P_WAITED) != 0 ||
1037 ((p->p_flags & P_TRACED) == 0 &&
1038 (options & WUNTRACED) == 0)) {
1039 lwkt_reltoken(&p->p_token);
1044 p->p_flags |= P_WAITED;
1048 *status = W_STOPCODE(p->p_xstat);
1049 /* Zero rusage so we get something consistent. */
1051 bzero(rusage, sizeof(*rusage));
1053 lwkt_reltoken(&p->p_token);
1057 if ((options & WCONTINUED) && (p->p_flags & P_CONTINUED)) {
1059 lwkt_gettoken(&p->p_token);
1060 if (p->p_pptr != q) {
1061 lwkt_reltoken(&p->p_token);
1065 if ((p->p_flags & P_CONTINUED) == 0) {
1066 lwkt_reltoken(&p->p_token);
1072 p->p_flags &= ~P_CONTINUED;
1077 lwkt_reltoken(&p->p_token);
1086 if (options & WNOHANG) {
1093 * Wait for signal - interlocked using q->p_token.
1095 error = tsleep(q, PCATCH, "wait", 0);
1098 lwkt_reltoken(&q->p_token);
1105 * Change child's parent process to parent.
1107 * p_children/p_sibling requires the parent's token, and
1108 * changing pptr requires the child's token, so we have to
1109 * get three tokens to do this operation. We also need to
1110 * hold pointers that might get ripped out from under us to
1111 * preserve structural integrity.
1113 * It is possible to race another reparent or disconnect or other
1114 * similar operation. We must retry when this situation occurs.
1115 * Once we successfully reparent the process we no longer care
1119 proc_reparent(struct proc *child, struct proc *parent)
1124 while ((opp = child->p_pptr) != parent) {
1126 lwkt_gettoken(&opp->p_token);
1127 lwkt_gettoken(&child->p_token);
1128 lwkt_gettoken(&parent->p_token);
1129 if (child->p_pptr != opp) {
1130 lwkt_reltoken(&parent->p_token);
1131 lwkt_reltoken(&child->p_token);
1132 lwkt_reltoken(&opp->p_token);
1136 LIST_REMOVE(child, p_sibling);
1137 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
1138 child->p_pptr = parent;
1139 lwkt_reltoken(&parent->p_token);
1140 lwkt_reltoken(&child->p_token);
1141 lwkt_reltoken(&opp->p_token);
1142 if (LIST_EMPTY(&opp->p_children))
1151 * The next two functions are to handle adding/deleting items on the
1155 * Take the arguments given and put them onto the exit callout list,
1156 * However first make sure that it's not already there.
1157 * returns 0 on success.
1161 at_exit(exitlist_fn function)
1163 struct exitlist *ep;
1166 /* Be noisy if the programmer has lost track of things */
1167 if (rm_at_exit(function))
1168 kprintf("WARNING: exit callout entry (%p) already present\n",
1171 ep = kmalloc(sizeof(*ep), M_ATEXIT, M_NOWAIT);
1174 ep->function = function;
1175 TAILQ_INSERT_TAIL(&exit_list, ep, next);
1180 * Scan the exit callout list for the given item and remove it.
1181 * Returns the number of items removed (0 or 1)
1184 rm_at_exit(exitlist_fn function)
1186 struct exitlist *ep;
1188 TAILQ_FOREACH(ep, &exit_list, next) {
1189 if (ep->function == function) {
1190 TAILQ_REMOVE(&exit_list, ep, next);
1191 kfree(ep, M_ATEXIT);
1199 * LWP reaper related code.
1202 reaplwps(void *context, int dummy)
1204 struct lwplist *lwplist = context;
1208 lwkt_gettoken(&deadlwp_token[cpu]);
1209 while ((lp = LIST_FIRST(lwplist))) {
1210 LIST_REMOVE(lp, u.lwp_reap_entry);
1213 lwkt_reltoken(&deadlwp_token[cpu]);
1217 reaplwp(struct lwp *lp)
1219 while (lwp_wait(lp) == 0)
1229 for (cpu = 0; cpu < ncpus; cpu++) {
1230 lwkt_token_init(&deadlwp_token[cpu], "deadlwpl");
1231 LIST_INIT(&deadlwp_list[cpu]);
1232 deadlwp_task[cpu] = kmalloc(sizeof(*deadlwp_task[cpu]),
1233 M_DEVBUF, M_WAITOK);
1234 TASK_INIT(deadlwp_task[cpu], 0, reaplwps, &deadlwp_list[cpu]);
1238 SYSINIT(deadlwpinit, SI_SUB_CONFIGURE, SI_ORDER_ANY, deadlwp_init, NULL);