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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 static void reaplwps(void *context, int dummy);
80 static void reaplwp(struct lwp *lp);
81 static void killlwps(struct lwp *lp);
83 static MALLOC_DEFINE(M_ATEXIT, "atexit", "atexit callback");
85 static struct lwkt_token deadlwp_token = LWKT_TOKEN_INITIALIZER(deadlwp_token);
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 struct task *deadlwp_task[MAXCPU];
102 struct lwplist deadlwp_list[MAXCPU];
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.
124 sys_extexit(struct extexit_args *uap)
126 struct proc *p = curproc;
130 action = EXTEXIT_ACTION(uap->how);
131 who = EXTEXIT_WHO(uap->how);
133 /* Check parameters before we might perform some action */
146 error = copyout(&uap->status, uap->addr, sizeof(uap->status));
154 lwkt_gettoken(&p->p_token);
159 * Be sure only to perform a simple lwp exit if there is at
160 * least one more lwp in the proc, which will call exit1()
161 * later, otherwise the proc will be an UNDEAD and not even a
164 if (p->p_nthreads > 1) {
165 lwp_exit(0); /* called w/ p_token held */
168 /* else last lwp in proc: do the real thing */
170 default: /* to help gcc */
172 lwkt_reltoken(&p->p_token);
173 exit1(W_EXITCODE(uap->status, 0));
178 lwkt_reltoken(&p->p_token); /* safety */
182 * Kill all lwps associated with the current process except the
183 * current lwp. Return an error if we race another thread trying to
184 * do the same thing and lose the race.
186 * If forexec is non-zero the current thread and process flags are
187 * cleaned up so they can be reused.
189 * Caller must hold curproc->p_token
192 killalllwps(int forexec)
194 struct lwp *lp = curthread->td_lwp;
195 struct proc *p = lp->lwp_proc;
198 * Interlock against P_WEXIT. Only one of the process's thread
199 * is allowed to do the master exit.
201 if (p->p_flags & P_WEXIT)
203 p->p_flags |= P_WEXIT;
206 * Interlock with LWP_MP_WEXIT and kill any remaining LWPs
208 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT);
209 if (p->p_nthreads > 1)
213 * If doing this for an exec, clean up the remaining thread
214 * (us) for continuing operation after all the other threads
218 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_WEXIT);
219 p->p_flags &= ~P_WEXIT;
225 * Kill all LWPs except the current one. Do not try to signal
226 * LWPs which have exited on their own or have already been
230 killlwps(struct lwp *lp)
232 struct proc *p = lp->lwp_proc;
236 * Kill the remaining LWPs. We must send the signal before setting
237 * LWP_MP_WEXIT. The setting of WEXIT is optional but helps reduce
238 * races. tlp must be held across the call as it might block and
239 * allow the target lwp to rip itself out from under our loop.
241 FOREACH_LWP_IN_PROC(tlp, p) {
243 lwkt_gettoken(&tlp->lwp_token);
244 if ((tlp->lwp_mpflags & LWP_MP_WEXIT) == 0) {
245 lwpsignal(p, tlp, SIGKILL);
246 atomic_set_int(&tlp->lwp_mpflags, LWP_MP_WEXIT);
248 lwkt_reltoken(&tlp->lwp_token);
253 * Wait for everything to clear out.
255 while (p->p_nthreads > 1) {
256 tsleep(&p->p_nthreads, 0, "killlwps", 0);
261 * Exit: deallocate address space and other resources, change proc state
262 * to zombie, and unlink proc from allproc and parent's lists. Save exit
263 * status and rusage for wait(). Check for child processes and orphan them.
268 struct thread *td = curthread;
269 struct proc *p = td->td_proc;
270 struct lwp *lp = td->td_lwp;
277 lwkt_gettoken(&p->p_token);
280 kprintf("init died (signal %d, exit %d)\n",
281 WTERMSIG(rv), WEXITSTATUS(rv));
282 panic("Going nowhere without my init!");
284 varsymset_clean(&p->p_varsymset);
285 lockuninit(&p->p_varsymset.vx_lock);
288 * Kill all lwps associated with the current process, return an
289 * error if we race another thread trying to do the same thing
292 error = killalllwps(0);
298 /* are we a task leader? */
299 if (p == p->p_leader) {
300 struct kill_args killArgs;
301 killArgs.signum = SIGKILL;
304 killArgs.pid = q->p_pid;
306 * The interface for kill is better
307 * than the internal signal
313 tsleep((caddr_t)p, 0, "exit1", 0);
319 STOPEVENT(p, S_EXIT, rv);
320 p->p_flags |= P_POSTEXIT; /* stop procfs stepping */
323 * Check if any loadable modules need anything done at process exit.
324 * e.g. SYSV IPC stuff
325 * XXX what if one of these generates an error?
328 EVENTHANDLER_INVOKE(process_exit, p);
331 * XXX: imho, the eventhandler stuff is much cleaner than this.
332 * Maybe we should move everything to use eventhandler.
334 TAILQ_FOREACH(ep, &exit_list, next)
337 if (p->p_flags & P_PROFIL)
340 SIGEMPTYSET(p->p_siglist);
341 SIGEMPTYSET(lp->lwp_siglist);
342 if (timevalisset(&p->p_realtimer.it_value))
343 callout_stop_sync(&p->p_ithandle);
346 * Reset any sigio structures pointing to us as a result of
347 * F_SETOWN with our pid.
349 funsetownlst(&p->p_sigiolst);
352 * Close open files and release open-file table.
357 if(p->p_leader->p_peers) {
359 while(q->p_peers != p)
361 q->p_peers = p->p_peers;
362 wakeup((caddr_t)p->p_leader);
366 * XXX Shutdown SYSV semaphores
370 KKASSERT(p->p_numposixlocks == 0);
372 /* The next two chunks should probably be moved to vmspace_exit. */
376 * Clean up data related to virtual kernel operation. Clean up
377 * any vkernel context related to the current lwp now so we can
381 vkernel_lwp_exit(lp);
386 * Release user portion of address space.
387 * This releases references to vnodes,
388 * which could cause I/O if the file has been unlinked.
389 * Need to do this early enough that we can still sleep.
390 * Can't free the entire vmspace as the kernel stack
391 * may be mapped within that space also.
393 * Processes sharing the same vmspace may exit in one order, and
394 * get cleaned up by vmspace_exit() in a different order. The
395 * last exiting process to reach this point releases as much of
396 * the environment as it can, and the last process cleaned up
397 * by vmspace_exit() (which decrements exitingcnt) cleans up the
400 vmspace_exitbump(vm);
401 sysref_put(&vm->vm_sysref);
403 if (SESS_LEADER(p)) {
404 struct session *sp = p->p_session;
408 * We are the controlling process. Signal the
409 * foreground process group, drain the controlling
410 * terminal, and revoke access to the controlling
413 * NOTE: while waiting for the process group to exit
414 * it is possible that one of the processes in the
415 * group will revoke the tty, so the ttyclosesession()
416 * function will re-check sp->s_ttyvp.
418 if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) {
419 if (sp->s_ttyp->t_pgrp)
420 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1);
422 ttyclosesession(sp, 1); /* also revoke */
425 * Release the tty. If someone has it open via
426 * /dev/tty then close it (since they no longer can
427 * once we've NULL'd it out).
429 ttyclosesession(sp, 0);
432 * s_ttyp is not zero'd; we use this to indicate
433 * that the session once had a controlling terminal.
434 * (for logging and informational purposes)
439 fixjobc(p, p->p_pgrp, 0);
440 (void)acct_process(p);
446 ktrdestroy(&p->p_tracenode);
450 * Release reference to text vnode
452 if ((vtmp = p->p_textvp) != NULL) {
457 /* Release namecache handle to text file */
458 if (p->p_textnch.ncp)
459 cache_drop(&p->p_textnch);
462 * We have to handle PPWAIT here or proc_move_allproc_zombie()
463 * will block on the PHOLD() the parent is doing.
465 if (p->p_flags & P_PPWAIT) {
466 p->p_flags &= ~P_PPWAIT;
471 * Move the process to the zombie list. This will block
472 * until the process p_lock count reaches 0. The process will
473 * not be reaped until TDF_EXITING is set by cpu_thread_exit(),
474 * which is called from cpu_proc_exit().
476 proc_move_allproc_zombie(p);
479 * Reparent all of this process's children to the init process.
480 * We must hold initproc->p_token in order to mess with
481 * initproc->p_children. We already hold p->p_token (to remove
482 * the children from our list).
484 q = LIST_FIRST(&p->p_children);
486 lwkt_gettoken(&initproc->p_token);
487 while ((q = LIST_FIRST(&p->p_children)) != NULL) {
489 lwkt_gettoken(&q->p_token);
490 if (q != LIST_FIRST(&p->p_children)) {
491 lwkt_reltoken(&q->p_token);
495 LIST_REMOVE(q, p_sibling);
496 LIST_INSERT_HEAD(&initproc->p_children, q, p_sibling);
497 q->p_pptr = initproc;
498 q->p_sigparent = SIGCHLD;
501 * Traced processes are killed
502 * since their existence means someone is screwing up.
504 if (q->p_flags & P_TRACED) {
505 q->p_flags &= ~P_TRACED;
508 lwkt_reltoken(&q->p_token);
511 lwkt_reltoken(&initproc->p_token);
516 * Save exit status and final rusage info, adding in child rusage
517 * info and self times.
519 calcru_proc(p, &p->p_ru);
520 ruadd(&p->p_ru, &p->p_cru);
523 * notify interested parties of our demise.
525 KNOTE(&p->p_klist, NOTE_EXIT);
528 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT
529 * flag set, or if the handler is set to SIG_IGN, notify process 1
530 * instead (and hope it will handle this situation).
532 if (p->p_pptr->p_sigacts->ps_flag & (PS_NOCLDWAIT | PS_CLDSIGIGN)) {
533 proc_reparent(p, initproc);
536 /* lwkt_gettoken(&proc_token); */
539 if (p->p_sigparent && q != initproc) {
540 ksignal(q, p->p_sigparent);
545 p->p_flags &= ~P_TRACED;
549 /* lwkt_reltoken(&proc_token); */
550 /* NOTE: p->p_pptr can get ripped out */
552 * cpu_exit is responsible for clearing curproc, since
553 * it is heavily integrated with the thread/switching sequence.
555 * Other substructures are freed from wait().
560 * Release the current user process designation on the process so
561 * the userland scheduler can work in someone else.
563 p->p_usched->release_curproc(lp);
566 * Finally, call machine-dependent code to release as many of the
567 * lwp's resources as we can and halt execution of this thread.
573 * Eventually called by every exiting LWP
575 * p->p_token must be held. mplock may be held and will be released.
578 lwp_exit(int masterexit)
580 struct thread *td = curthread;
581 struct lwp *lp = td->td_lwp;
582 struct proc *p = lp->lwp_proc;
586 * lwp_exit() may be called without setting LWP_MP_WEXIT, so
587 * make sure it is set here.
589 ASSERT_LWKT_TOKEN_HELD(&p->p_token);
590 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT);
593 * Clean up any virtualization
596 vkernel_lwp_exit(lp);
599 * Clean up select/poll support
601 kqueue_terminate(&lp->lwp_kqueue);
604 * Clean up any syscall-cached ucred
607 crfree(td->td_ucred);
612 * Nobody actually wakes us when the lock
613 * count reaches zero, so just wait one tick.
615 while (lp->lwp_lock > 0)
616 tsleep(lp, 0, "lwpexit", 1);
618 /* Hand down resource usage to our proc */
619 ruadd(&p->p_ru, &lp->lwp_ru);
622 * If we don't hold the process until the LWP is reaped wait*()
623 * may try to dispose of its vmspace before all the LWPs have
624 * actually terminated.
629 * Do any remaining work that might block on us. We should be
630 * coded such that further blocking is ok after decrementing
631 * p_nthreads but don't take the chance.
633 dsched_exit_thread(td);
634 biosched_done(curthread);
637 * We have to use the reaper for all the LWPs except the one doing
638 * the master exit. The LWP doing the master exit can just be
639 * left on p_lwps and the process reaper will deal with it
640 * synchronously, which is much faster.
642 * Wakeup anyone waiting on p_nthreads to drop to 1 or 0.
644 * The process is left held until the reaper calls lwp_dispose() on
645 * the lp (after calling lwp_wait()).
647 if (masterexit == 0) {
648 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp);
650 if (p->p_nthreads <= 1)
652 lwkt_gettoken(&deadlwp_token);
653 LIST_INSERT_HEAD(&deadlwp_list[mycpuid], lp, u.lwp_reap_entry);
654 taskqueue_enqueue(taskqueue_thread[mycpuid],
655 deadlwp_task[mycpuid]);
656 lwkt_reltoken(&deadlwp_token);
659 if (p->p_nthreads <= 1)
664 * Release p_token. Issue the wakeup() on p_nthreads if necessary,
665 * as late as possible to give us a chance to actually deschedule and
666 * switch away before another cpu core hits reaplwp().
668 lwkt_reltoken(&p->p_token);
670 wakeup(&p->p_nthreads);
673 * Tell the userland scheduler that we are going away
675 p->p_usched->heuristic_exiting(lp, p);
681 * Wait until a lwp is completely dead. The final interlock in this drama
682 * is when TDF_EXITING is set in cpu_thread_exit() just before the final
685 * At the point TDF_EXITING is set a complete exit is accomplished when
686 * TDF_RUNNING and TDF_PREEMPT_LOCK are both clear. td_mpflags has two
687 * post-switch interlock flags that can be used to wait for the TDF_
690 * Returns non-zero on success, and zero if the caller needs to retry
694 lwp_wait(struct lwp *lp)
696 struct thread *td = lp->lwp_thread;
699 KKASSERT(lwkt_preempted_proc() != lp);
702 * This bit of code uses the thread destruction interlock
703 * managed by lwkt_switch_return() to wait for the lwp's
704 * thread to completely disengage.
706 * It is possible for us to race another cpu core so we
707 * have to do this correctly.
710 mpflags = td->td_mpflags;
712 if (mpflags & TDF_MP_EXITSIG)
714 tsleep_interlock(td, 0);
715 if (atomic_cmpset_int(&td->td_mpflags, mpflags,
716 mpflags | TDF_MP_EXITWAIT)) {
717 tsleep(td, PINTERLOCKED, "lwpxt", 0);
722 * We've already waited for the core exit but there can still
723 * be other refs from e.g. process scans and such.
725 if (lp->lwp_lock > 0) {
726 tsleep(lp, 0, "lwpwait1", 1);
730 tsleep(td, 0, "lwpwait2", 1);
735 * Now that we have the thread destruction interlock these flags
736 * really should already be cleaned up, keep a check for safety.
738 * We can't rip its stack out from under it until TDF_EXITING is
739 * set and both TDF_RUNNING and TDF_PREEMPT_LOCK are clear.
740 * TDF_PREEMPT_LOCK must be checked because TDF_RUNNING
741 * will be cleared temporarily if a thread gets preempted.
743 while ((td->td_flags & (TDF_RUNNING |
745 TDF_EXITING)) != TDF_EXITING) {
746 tsleep(lp, 0, "lwpwait3", 1);
750 KASSERT((td->td_flags & (TDF_RUNQ|TDF_TSLEEPQ)) == 0,
751 ("lwp_wait: td %p (%s) still on run or sleep queue",
757 * Release the resources associated with a lwp.
758 * The lwp must be completely dead.
761 lwp_dispose(struct lwp *lp)
763 struct thread *td = lp->lwp_thread;
765 KKASSERT(lwkt_preempted_proc() != lp);
766 KKASSERT(td->td_refs == 0);
767 KKASSERT((td->td_flags & (TDF_RUNNING |
769 TDF_EXITING)) == TDF_EXITING);
776 lp->lwp_thread = NULL;
777 lwkt_free_thread(td);
786 sys_wait4(struct wait_args *uap)
788 struct rusage rusage;
791 error = kern_wait(uap->pid, (uap->status ? &status : NULL),
792 uap->options, (uap->rusage ? &rusage : NULL),
793 &uap->sysmsg_result);
795 if (error == 0 && uap->status)
796 error = copyout(&status, uap->status, sizeof(*uap->status));
797 if (error == 0 && uap->rusage)
798 error = copyout(&rusage, uap->rusage, sizeof(*uap->rusage));
805 * wait_args(int pid, int *status, int options, struct rusage *rusage)
810 kern_wait(pid_t pid, int *status, int options, struct rusage *rusage, int *res)
812 struct thread *td = curthread;
814 struct proc *q = td->td_proc;
822 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WLINUXCLONE))
825 lwkt_gettoken(&q->p_token);
828 * All sorts of things can change due to blocking so we have to loop
829 * all the way back up here.
831 * The problem is that if a process group is stopped and the parent
832 * is doing a wait*(..., WUNTRACED, ...), it will see the STOP
833 * of the child and then stop itself when it tries to return from the
834 * system call. When the process group is resumed the parent will
835 * then get the STOP status even though the child has now resumed
836 * (a followup wait*() will get the CONT status).
838 * Previously the CONT would overwrite the STOP because the tstop
839 * was handled within tsleep(), and the parent would only see
840 * the CONT when both are stopped and continued together. This little
841 * two-line hack restores this effect.
843 while (q->p_stat == SSTOP)
851 * NOTE: We don't want to break q's p_token in the loop for the
852 * case where no children are found or we risk breaking the
853 * interlock between child and parent.
855 LIST_FOREACH(p, &q->p_children, p_sibling) {
856 if (pid != WAIT_ANY &&
857 p->p_pid != pid && p->p_pgid != -pid) {
862 * This special case handles a kthread spawned by linux_clone
863 * (see linux_misc.c). The linux_wait4 and linux_waitpid
864 * functions need to be able to distinguish between waiting
865 * on a process and waiting on a thread. It is a thread if
866 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
867 * signifies we want to wait for threads and not processes.
869 if ((p->p_sigparent != SIGCHLD) ^
870 ((options & WLINUXCLONE) != 0)) {
875 if (p->p_stat == SZOMB) {
877 * We may go into SZOMB with threads still present.
878 * We must wait for them to exit before we can reap
879 * the master thread, otherwise we may race reaping
880 * non-master threads.
882 * Only this routine can remove a process from
883 * the zombie list and destroy it, use PACQUIREZOMB()
884 * to serialize us and loop if it blocks (interlocked
885 * by the parent's q->p_token).
887 * WARNING! (p) can be invalid when PHOLDZOMB(p)
888 * returns non-zero. Be sure not to
893 lwkt_gettoken(&p->p_token);
894 if (p->p_pptr != q) {
895 lwkt_reltoken(&p->p_token);
899 while (p->p_nthreads > 0) {
900 tsleep(&p->p_nthreads, 0, "lwpzomb", hz);
904 * Reap any LWPs left in p->p_lwps. This is usually
905 * just the last LWP. This must be done before
906 * we loop on p_lock since the lwps hold a ref on
907 * it as a vmspace interlock.
909 * Once that is accomplished p_nthreads had better
912 while ((lp = RB_ROOT(&p->p_lwp_tree)) != NULL) {
913 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp);
916 KKASSERT(p->p_nthreads == 0);
919 * Don't do anything really bad until all references
920 * to the process go away. This may include other
921 * LWPs which are still in the process of being
922 * reaped. We can't just pull the rug out from under
923 * them because they may still be using the VM space.
925 * Certain kernel facilities such as /proc will also
926 * put a hold on the process for short periods of
930 PSTALL(p, "reap3", 0);
932 /* Take care of our return values. */
936 *status = p->p_xstat;
940 * If we got the child via a ptrace 'attach',
941 * we need to give it back to the old parent.
943 if (p->p_oppid && (t = pfind(p->p_oppid)) != NULL) {
951 lwkt_reltoken(&p->p_token);
957 * Unlink the proc from its process group so that
958 * the following operations won't lead to an
959 * inconsistent state for processes running down
962 proc_remove_zombie(p);
963 lwkt_reltoken(&p->p_token);
967 ruadd(&q->p_cru, &p->p_ru);
970 * Decrement the count of procs running with this uid.
972 chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
975 * Free up credentials.
981 * Remove unused arguments
985 if (pa && refcount_release(&pa->ar_ref)) {
992 if (ps && refcount_release(&ps->ps_refcnt)) {
993 kfree(ps, M_SUBPROC);
998 * Our exitingcount was incremented when the process
999 * became a zombie, now that the process has been
1000 * removed from (almost) all lists we should be able
1001 * to safely destroy its vmspace. Wait for any current
1002 * holders to go away (so the vmspace remains stable),
1005 PSTALL(p, "reap4", 0);
1006 vmspace_exitfree(p);
1007 PSTALL(p, "reap5", 0);
1010 * NOTE: We have to officially release ZOMB in order
1011 * to ensure that a racing thread in kern_wait()
1012 * which blocked on ZOMB is woken up.
1017 atomic_add_int(&nprocs, -1);
1021 if (p->p_stat == SSTOP && (p->p_flags & P_WAITED) == 0 &&
1022 ((p->p_flags & P_TRACED) || (options & WUNTRACED))) {
1024 lwkt_gettoken(&p->p_token);
1025 if (p->p_pptr != q) {
1026 lwkt_reltoken(&p->p_token);
1030 if (p->p_stat != SSTOP ||
1031 (p->p_flags & P_WAITED) != 0 ||
1032 ((p->p_flags & P_TRACED) == 0 &&
1033 (options & WUNTRACED) == 0)) {
1034 lwkt_reltoken(&p->p_token);
1039 p->p_flags |= P_WAITED;
1043 *status = W_STOPCODE(p->p_xstat);
1044 /* Zero rusage so we get something consistent. */
1046 bzero(rusage, sizeof(*rusage));
1048 lwkt_reltoken(&p->p_token);
1052 if ((options & WCONTINUED) && (p->p_flags & P_CONTINUED)) {
1054 lwkt_gettoken(&p->p_token);
1055 if (p->p_pptr != q) {
1056 lwkt_reltoken(&p->p_token);
1060 if ((p->p_flags & P_CONTINUED) == 0) {
1061 lwkt_reltoken(&p->p_token);
1067 p->p_flags &= ~P_CONTINUED;
1072 lwkt_reltoken(&p->p_token);
1081 if (options & WNOHANG) {
1088 * Wait for signal - interlocked using q->p_token.
1090 error = tsleep(q, PCATCH, "wait", 0);
1093 lwkt_reltoken(&q->p_token);
1100 * Change child's parent process to parent.
1102 * p_children/p_sibling requires the parent's token, and
1103 * changing pptr requires the child's token, so we have to
1104 * get three tokens to do this operation. We also need to
1105 * hold pointers that might get ripped out from under us to
1106 * preserve structural integrity.
1108 * It is possible to race another reparent or disconnect or other
1109 * similar operation. We must retry when this situation occurs.
1110 * Once we successfully reparent the process we no longer care
1114 proc_reparent(struct proc *child, struct proc *parent)
1119 while ((opp = child->p_pptr) != parent) {
1121 lwkt_gettoken(&opp->p_token);
1122 lwkt_gettoken(&child->p_token);
1123 lwkt_gettoken(&parent->p_token);
1124 if (child->p_pptr != opp) {
1125 lwkt_reltoken(&parent->p_token);
1126 lwkt_reltoken(&child->p_token);
1127 lwkt_reltoken(&opp->p_token);
1131 LIST_REMOVE(child, p_sibling);
1132 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
1133 child->p_pptr = parent;
1134 lwkt_reltoken(&parent->p_token);
1135 lwkt_reltoken(&child->p_token);
1136 lwkt_reltoken(&opp->p_token);
1137 if (LIST_EMPTY(&opp->p_children))
1146 * The next two functions are to handle adding/deleting items on the
1150 * Take the arguments given and put them onto the exit callout list,
1151 * However first make sure that it's not already there.
1152 * returns 0 on success.
1156 at_exit(exitlist_fn function)
1158 struct exitlist *ep;
1161 /* Be noisy if the programmer has lost track of things */
1162 if (rm_at_exit(function))
1163 kprintf("WARNING: exit callout entry (%p) already present\n",
1166 ep = kmalloc(sizeof(*ep), M_ATEXIT, M_NOWAIT);
1169 ep->function = function;
1170 TAILQ_INSERT_TAIL(&exit_list, ep, next);
1175 * Scan the exit callout list for the given item and remove it.
1176 * Returns the number of items removed (0 or 1)
1179 rm_at_exit(exitlist_fn function)
1181 struct exitlist *ep;
1183 TAILQ_FOREACH(ep, &exit_list, next) {
1184 if (ep->function == function) {
1185 TAILQ_REMOVE(&exit_list, ep, next);
1186 kfree(ep, M_ATEXIT);
1194 * LWP reaper related code.
1197 reaplwps(void *context, int dummy)
1199 struct lwplist *lwplist = context;
1202 lwkt_gettoken(&deadlwp_token);
1203 while ((lp = LIST_FIRST(lwplist))) {
1204 LIST_REMOVE(lp, u.lwp_reap_entry);
1207 lwkt_reltoken(&deadlwp_token);
1211 reaplwp(struct lwp *lp)
1213 while (lwp_wait(lp) == 0)
1223 for (cpu = 0; cpu < ncpus; cpu++) {
1224 LIST_INIT(&deadlwp_list[cpu]);
1225 deadlwp_task[cpu] = kmalloc(sizeof(*deadlwp_task[cpu]),
1226 M_DEVBUF, M_WAITOK);
1227 TASK_INIT(deadlwp_task[cpu], 0, reaplwps, &deadlwp_list[cpu]);
1231 SYSINIT(deadlwpinit, SI_SUB_CONFIGURE, SI_ORDER_ANY, deadlwp_init, NULL);