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38 * @(#)kern_exit.c 8.7 (Berkeley) 2/12/94
39 * $FreeBSD: src/sys/kern/kern_exit.c,v 1.92.2.11 2003/01/13 22:51:16 dillon Exp $
42 #include "opt_compat.h"
43 #include "opt_ktrace.h"
45 #include <sys/param.h>
46 #include <sys/systm.h>
47 #include <sys/sysproto.h>
48 #include <sys/kernel.h>
49 #include <sys/malloc.h>
51 #include <sys/ktrace.h>
52 #include <sys/pioctl.h>
55 #include <sys/vnode.h>
56 #include <sys/resourcevar.h>
57 #include <sys/signalvar.h>
58 #include <sys/taskqueue.h>
59 #include <sys/ptrace.h>
60 #include <sys/acct.h> /* for acct_process() function prototype */
61 #include <sys/filedesc.h>
65 #include <sys/kern_syscall.h>
66 #include <sys/upcall.h>
67 #include <sys/unistd.h>
68 #include <sys/eventhandler.h>
69 #include <sys/dsched.h>
72 #include <vm/vm_param.h>
75 #include <vm/vm_map.h>
76 #include <vm/vm_extern.h>
79 #include <sys/refcount.h>
80 #include <sys/thread2.h>
81 #include <sys/sysref2.h>
82 #include <sys/mplock2.h>
84 static void reaplwps(void *context, int dummy);
85 static void reaplwp(struct lwp *lp);
86 static void killlwps(struct lwp *lp);
88 static MALLOC_DEFINE(M_ATEXIT, "atexit", "atexit callback");
89 static MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status");
91 static struct lwkt_token deadlwp_token = LWKT_TOKEN_INITIALIZER(deadlwp_token);
94 * callout list for things to do at exit time
98 TAILQ_ENTRY(exitlist) next;
101 TAILQ_HEAD(exit_list_head, exitlist);
102 static struct exit_list_head exit_list = TAILQ_HEAD_INITIALIZER(exit_list);
107 struct task *deadlwp_task[MAXCPU];
108 struct lwplist deadlwp_list[MAXCPU];
114 * SYS_EXIT_ARGS(int rval)
117 sys_exit(struct exit_args *uap)
119 exit1(W_EXITCODE(uap->rval, 0));
125 * Death of a lwp or process with optional bells and whistles.
130 sys_extexit(struct extexit_args *uap)
132 struct proc *p = curproc;
136 action = EXTEXIT_ACTION(uap->how);
137 who = EXTEXIT_WHO(uap->how);
139 /* Check parameters before we might perform some action */
152 error = copyout(&uap->status, uap->addr, sizeof(uap->status));
160 lwkt_gettoken(&p->p_token);
165 * Be sure only to perform a simple lwp exit if there is at
166 * least one more lwp in the proc, which will call exit1()
167 * later, otherwise the proc will be an UNDEAD and not even a
170 if (p->p_nthreads > 1) {
171 lwp_exit(0); /* called w/ p_token held */
174 /* else last lwp in proc: do the real thing */
176 default: /* to help gcc */
178 lwkt_reltoken(&p->p_token);
179 exit1(W_EXITCODE(uap->status, 0));
184 lwkt_reltoken(&p->p_token); /* safety */
188 * Kill all lwps associated with the current process except the
189 * current lwp. Return an error if we race another thread trying to
190 * do the same thing and lose the race.
192 * If forexec is non-zero the current thread and process flags are
193 * cleaned up so they can be reused.
195 * Caller must hold curproc->p_token
198 killalllwps(int forexec)
200 struct lwp *lp = curthread->td_lwp;
201 struct proc *p = lp->lwp_proc;
204 * Interlock against P_WEXIT. Only one of the process's thread
205 * is allowed to do the master exit.
207 if (p->p_flags & P_WEXIT)
209 p->p_flags |= P_WEXIT;
212 * Interlock with LWP_MP_WEXIT and kill any remaining LWPs
214 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT);
215 if (p->p_nthreads > 1)
219 * If doing this for an exec, clean up the remaining thread
220 * (us) for continuing operation after all the other threads
224 atomic_clear_int(&lp->lwp_mpflags, LWP_MP_WEXIT);
225 p->p_flags &= ~P_WEXIT;
231 * Kill all LWPs except the current one. Do not try to signal
232 * LWPs which have exited on their own or have already been
236 killlwps(struct lwp *lp)
238 struct proc *p = lp->lwp_proc;
242 * Kill the remaining LWPs. We must send the signal before setting
243 * LWP_MP_WEXIT. The setting of WEXIT is optional but helps reduce
244 * races. tlp must be held across the call as it might block and
245 * allow the target lwp to rip itself out from under our loop.
247 FOREACH_LWP_IN_PROC(tlp, p) {
249 lwkt_gettoken(&tlp->lwp_token);
250 if ((tlp->lwp_mpflags & LWP_MP_WEXIT) == 0) {
251 lwpsignal(p, tlp, SIGKILL);
252 atomic_set_int(&tlp->lwp_mpflags, LWP_MP_WEXIT);
254 lwkt_reltoken(&tlp->lwp_token);
259 * Wait for everything to clear out.
261 while (p->p_nthreads > 1) {
262 tsleep(&p->p_nthreads, 0, "killlwps", 0);
267 * Exit: deallocate address space and other resources, change proc state
268 * to zombie, and unlink proc from allproc and parent's lists. Save exit
269 * status and rusage for wait(). Check for child processes and orphan them.
274 struct thread *td = curthread;
275 struct proc *p = td->td_proc;
276 struct lwp *lp = td->td_lwp;
283 lwkt_gettoken(&p->p_token);
286 kprintf("init died (signal %d, exit %d)\n",
287 WTERMSIG(rv), WEXITSTATUS(rv));
288 panic("Going nowhere without my init!");
290 varsymset_clean(&p->p_varsymset);
291 lockuninit(&p->p_varsymset.vx_lock);
294 * Kill all lwps associated with the current process, return an
295 * error if we race another thread trying to do the same thing
298 error = killalllwps(0);
304 /* are we a task leader? */
305 if (p == p->p_leader) {
306 struct kill_args killArgs;
307 killArgs.signum = SIGKILL;
310 killArgs.pid = q->p_pid;
312 * The interface for kill is better
313 * than the internal signal
320 tsleep((caddr_t)p, 0, "exit1", 0);
326 STOPEVENT(p, S_EXIT, rv);
327 p->p_flags |= P_POSTEXIT; /* stop procfs stepping */
330 * Check if any loadable modules need anything done at process exit.
331 * e.g. SYSV IPC stuff
332 * XXX what if one of these generates an error?
335 EVENTHANDLER_INVOKE(process_exit, p);
338 * XXX: imho, the eventhandler stuff is much cleaner than this.
339 * Maybe we should move everything to use eventhandler.
341 TAILQ_FOREACH(ep, &exit_list, next)
344 if (p->p_flags & P_PROFIL)
347 SIGEMPTYSET(p->p_siglist);
348 SIGEMPTYSET(lp->lwp_siglist);
349 if (timevalisset(&p->p_realtimer.it_value))
350 callout_stop_sync(&p->p_ithandle);
353 * Reset any sigio structures pointing to us as a result of
354 * F_SETOWN with our pid.
356 funsetownlst(&p->p_sigiolst);
359 * Close open files and release open-file table.
364 if(p->p_leader->p_peers) {
366 while(q->p_peers != p)
368 q->p_peers = p->p_peers;
369 wakeup((caddr_t)p->p_leader);
373 * XXX Shutdown SYSV semaphores
377 KKASSERT(p->p_numposixlocks == 0);
379 /* The next two chunks should probably be moved to vmspace_exit. */
383 * Release upcalls associated with this process
389 * Clean up data related to virtual kernel operation. Clean up
390 * any vkernel context related to the current lwp now so we can
394 vkernel_lwp_exit(lp);
399 * Release user portion of address space.
400 * This releases references to vnodes,
401 * which could cause I/O if the file has been unlinked.
402 * Need to do this early enough that we can still sleep.
403 * Can't free the entire vmspace as the kernel stack
404 * may be mapped within that space also.
406 * Processes sharing the same vmspace may exit in one order, and
407 * get cleaned up by vmspace_exit() in a different order. The
408 * last exiting process to reach this point releases as much of
409 * the environment as it can, and the last process cleaned up
410 * by vmspace_exit() (which decrements exitingcnt) cleans up the
413 vmspace_exitbump(vm);
414 sysref_put(&vm->vm_sysref);
416 if (SESS_LEADER(p)) {
417 struct session *sp = p->p_session;
421 * We are the controlling process. Signal the
422 * foreground process group, drain the controlling
423 * terminal, and revoke access to the controlling
426 * NOTE: while waiting for the process group to exit
427 * it is possible that one of the processes in the
428 * group will revoke the tty, so the ttyclosesession()
429 * function will re-check sp->s_ttyvp.
431 if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) {
432 if (sp->s_ttyp->t_pgrp)
433 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1);
435 ttyclosesession(sp, 1); /* also revoke */
438 * Release the tty. If someone has it open via
439 * /dev/tty then close it (since they no longer can
440 * once we've NULL'd it out).
442 ttyclosesession(sp, 0);
445 * s_ttyp is not zero'd; we use this to indicate
446 * that the session once had a controlling terminal.
447 * (for logging and informational purposes)
452 fixjobc(p, p->p_pgrp, 0);
453 (void)acct_process(p);
459 ktrdestroy(&p->p_tracenode);
463 * Release reference to text vnode
465 if ((vtmp = p->p_textvp) != NULL) {
470 /* Release namecache handle to text file */
471 if (p->p_textnch.ncp)
472 cache_drop(&p->p_textnch);
475 * We have to handle PPWAIT here or proc_move_allproc_zombie()
476 * will block on the PHOLD() the parent is doing.
478 if (p->p_flags & P_PPWAIT) {
479 p->p_flags &= ~P_PPWAIT;
484 * Move the process to the zombie list. This will block
485 * until the process p_lock count reaches 0. The process will
486 * not be reaped until TDF_EXITING is set by cpu_thread_exit(),
487 * which is called from cpu_proc_exit().
489 proc_move_allproc_zombie(p);
492 * Reparent all of this process's children to the init process.
493 * We must hold initproc->p_token in order to mess with
494 * initproc->p_children. We already hold p->p_token (to remove
495 * the children from our list).
497 q = LIST_FIRST(&p->p_children);
499 lwkt_gettoken(&initproc->p_token);
500 while ((q = LIST_FIRST(&p->p_children)) != NULL) {
502 lwkt_gettoken(&q->p_token);
503 if (q != LIST_FIRST(&p->p_children)) {
504 lwkt_reltoken(&q->p_token);
508 LIST_REMOVE(q, p_sibling);
509 LIST_INSERT_HEAD(&initproc->p_children, q, p_sibling);
510 q->p_pptr = initproc;
511 q->p_sigparent = SIGCHLD;
514 * Traced processes are killed
515 * since their existence means someone is screwing up.
517 if (q->p_flags & P_TRACED) {
518 q->p_flags &= ~P_TRACED;
521 lwkt_reltoken(&q->p_token);
524 lwkt_reltoken(&initproc->p_token);
529 * Save exit status and final rusage info, adding in child rusage
530 * info and self times.
532 calcru_proc(p, &p->p_ru);
533 ruadd(&p->p_ru, &p->p_cru);
536 * notify interested parties of our demise.
538 KNOTE(&p->p_klist, NOTE_EXIT);
541 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT
542 * flag set, or if the handler is set to SIG_IGN, notify process 1
543 * instead (and hope it will handle this situation).
545 if (p->p_pptr->p_sigacts->ps_flag & (PS_NOCLDWAIT | PS_CLDSIGIGN)) {
546 proc_reparent(p, initproc);
549 /* lwkt_gettoken(&proc_token); */
552 if (p->p_sigparent && q != initproc) {
553 ksignal(q, p->p_sigparent);
558 p->p_flags &= ~P_TRACED;
562 /* lwkt_reltoken(&proc_token); */
563 /* NOTE: p->p_pptr can get ripped out */
565 * cpu_exit is responsible for clearing curproc, since
566 * it is heavily integrated with the thread/switching sequence.
568 * Other substructures are freed from wait().
573 * Release the current user process designation on the process so
574 * the userland scheduler can work in someone else.
576 p->p_usched->release_curproc(lp);
579 * Finally, call machine-dependent code to release as many of the
580 * lwp's resources as we can and halt execution of this thread.
586 * Eventually called by every exiting LWP
588 * p->p_token must be held. mplock may be held and will be released.
591 lwp_exit(int masterexit)
593 struct thread *td = curthread;
594 struct lwp *lp = td->td_lwp;
595 struct proc *p = lp->lwp_proc;
599 * lwp_exit() may be called without setting LWP_MP_WEXIT, so
600 * make sure it is set here.
602 ASSERT_LWKT_TOKEN_HELD(&p->p_token);
603 atomic_set_int(&lp->lwp_mpflags, LWP_MP_WEXIT);
606 * Clean up any virtualization
609 vkernel_lwp_exit(lp);
612 * Clean up select/poll support
614 kqueue_terminate(&lp->lwp_kqueue);
617 * Clean up any syscall-cached ucred
620 crfree(td->td_ucred);
625 * Nobody actually wakes us when the lock
626 * count reaches zero, so just wait one tick.
628 while (lp->lwp_lock > 0)
629 tsleep(lp, 0, "lwpexit", 1);
631 /* Hand down resource usage to our proc */
632 ruadd(&p->p_ru, &lp->lwp_ru);
635 * If we don't hold the process until the LWP is reaped wait*()
636 * may try to dispose of its vmspace before all the LWPs have
637 * actually terminated.
642 * Do any remaining work that might block on us. We should be
643 * coded such that further blocking is ok after decrementing
644 * p_nthreads but don't take the chance.
646 dsched_exit_thread(td);
647 biosched_done(curthread);
650 * We have to use the reaper for all the LWPs except the one doing
651 * the master exit. The LWP doing the master exit can just be
652 * left on p_lwps and the process reaper will deal with it
653 * synchronously, which is much faster.
655 * Wakeup anyone waiting on p_nthreads to drop to 1 or 0.
657 * The process is left held until the reaper calls lwp_dispose() on
658 * the lp (after calling lwp_wait()).
660 if (masterexit == 0) {
661 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp);
663 if (p->p_nthreads <= 1)
665 lwkt_gettoken(&deadlwp_token);
666 LIST_INSERT_HEAD(&deadlwp_list[mycpuid], lp, u.lwp_reap_entry);
667 taskqueue_enqueue(taskqueue_thread[mycpuid],
668 deadlwp_task[mycpuid]);
669 lwkt_reltoken(&deadlwp_token);
672 if (p->p_nthreads <= 1)
677 * Release p_token. Issue the wakeup() on p_nthreads if necessary,
678 * as late as possible to give us a chance to actually deschedule and
679 * switch away before another cpu core hits reaplwp().
681 lwkt_reltoken(&p->p_token);
683 wakeup(&p->p_nthreads);
686 * Tell the userland scheduler that we are going away
688 p->p_usched->heuristic_exiting(lp, p);
694 * Wait until a lwp is completely dead. The final interlock in this drama
695 * is when TDF_EXITING is set in cpu_thread_exit() just before the final
698 * At the point TDF_EXITING is set a complete exit is accomplished when
699 * TDF_RUNNING and TDF_PREEMPT_LOCK are both clear. td_mpflags has two
700 * post-switch interlock flags that can be used to wait for the TDF_
703 * Returns non-zero on success, and zero if the caller needs to retry
707 lwp_wait(struct lwp *lp)
709 struct thread *td = lp->lwp_thread;
712 KKASSERT(lwkt_preempted_proc() != lp);
715 * This bit of code uses the thread destruction interlock
716 * managed by lwkt_switch_return() to wait for the lwp's
717 * thread to completely disengage.
719 * It is possible for us to race another cpu core so we
720 * have to do this correctly.
723 mpflags = td->td_mpflags;
725 if (mpflags & TDF_MP_EXITSIG)
727 tsleep_interlock(td, 0);
728 if (atomic_cmpset_int(&td->td_mpflags, mpflags,
729 mpflags | TDF_MP_EXITWAIT)) {
730 tsleep(td, PINTERLOCKED, "lwpxt", 0);
735 * We've already waited for the core exit but there can still
736 * be other refs from e.g. process scans and such.
738 if (lp->lwp_lock > 0) {
739 tsleep(lp, 0, "lwpwait1", 1);
743 tsleep(td, 0, "lwpwait2", 1);
748 * Now that we have the thread destruction interlock these flags
749 * really should already be cleaned up, keep a check for safety.
751 * We can't rip its stack out from under it until TDF_EXITING is
752 * set and both TDF_RUNNING and TDF_PREEMPT_LOCK are clear.
753 * TDF_PREEMPT_LOCK must be checked because TDF_RUNNING
754 * will be cleared temporarily if a thread gets preempted.
756 while ((td->td_flags & (TDF_RUNNING |
758 TDF_EXITING)) != TDF_EXITING) {
759 tsleep(lp, 0, "lwpwait3", 1);
763 KASSERT((td->td_flags & (TDF_RUNQ|TDF_TSLEEPQ)) == 0,
764 ("lwp_wait: td %p (%s) still on run or sleep queue",
770 * Release the resources associated with a lwp.
771 * The lwp must be completely dead.
774 lwp_dispose(struct lwp *lp)
776 struct thread *td = lp->lwp_thread;
778 KKASSERT(lwkt_preempted_proc() != lp);
779 KKASSERT(td->td_refs == 0);
780 KKASSERT((td->td_flags & (TDF_RUNNING |
782 TDF_EXITING)) == TDF_EXITING);
789 lp->lwp_thread = NULL;
790 lwkt_free_thread(td);
799 sys_wait4(struct wait_args *uap)
801 struct rusage rusage;
804 error = kern_wait(uap->pid, (uap->status ? &status : NULL),
805 uap->options, (uap->rusage ? &rusage : NULL),
806 &uap->sysmsg_result);
808 if (error == 0 && uap->status)
809 error = copyout(&status, uap->status, sizeof(*uap->status));
810 if (error == 0 && uap->rusage)
811 error = copyout(&rusage, uap->rusage, sizeof(*uap->rusage));
818 * wait_args(int pid, int *status, int options, struct rusage *rusage)
823 kern_wait(pid_t pid, int *status, int options, struct rusage *rusage, int *res)
825 struct thread *td = curthread;
827 struct proc *q = td->td_proc;
835 if (options &~ (WUNTRACED|WNOHANG|WCONTINUED|WLINUXCLONE))
838 lwkt_gettoken(&q->p_token);
841 * All sorts of things can change due to blocking so we have to loop
842 * all the way back up here.
844 * The problem is that if a process group is stopped and the parent
845 * is doing a wait*(..., WUNTRACED, ...), it will see the STOP
846 * of the child and then stop itself when it tries to return from the
847 * system call. When the process group is resumed the parent will
848 * then get the STOP status even though the child has now resumed
849 * (a followup wait*() will get the CONT status).
851 * Previously the CONT would overwrite the STOP because the tstop
852 * was handled within tsleep(), and the parent would only see
853 * the CONT when both are stopped and continued together. This little
854 * two-line hack restores this effect.
856 while (q->p_stat == SSTOP)
864 * NOTE: We don't want to break q's p_token in the loop for the
865 * case where no children are found or we risk breaking the
866 * interlock between child and parent.
868 LIST_FOREACH(p, &q->p_children, p_sibling) {
869 if (pid != WAIT_ANY &&
870 p->p_pid != pid && p->p_pgid != -pid) {
875 * This special case handles a kthread spawned by linux_clone
876 * (see linux_misc.c). The linux_wait4 and linux_waitpid
877 * functions need to be able to distinguish between waiting
878 * on a process and waiting on a thread. It is a thread if
879 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
880 * signifies we want to wait for threads and not processes.
882 if ((p->p_sigparent != SIGCHLD) ^
883 ((options & WLINUXCLONE) != 0)) {
888 if (p->p_stat == SZOMB) {
890 * We may go into SZOMB with threads still present.
891 * We must wait for them to exit before we can reap
892 * the master thread, otherwise we may race reaping
893 * non-master threads.
895 * Only this routine can remove a process from
896 * the zombie list and destroy it, use PACQUIREZOMB()
897 * to serialize us and loop if it blocks (interlocked
898 * by the parent's q->p_token).
900 * WARNING! (p) can be invalid when PHOLDZOMB(p)
901 * returns non-zero. Be sure not to
906 lwkt_gettoken(&p->p_token);
907 if (p->p_pptr != q) {
908 lwkt_reltoken(&p->p_token);
912 while (p->p_nthreads > 0) {
913 tsleep(&p->p_nthreads, 0, "lwpzomb", hz);
917 * Reap any LWPs left in p->p_lwps. This is usually
918 * just the last LWP. This must be done before
919 * we loop on p_lock since the lwps hold a ref on
920 * it as a vmspace interlock.
922 * Once that is accomplished p_nthreads had better
925 while ((lp = RB_ROOT(&p->p_lwp_tree)) != NULL) {
926 lwp_rb_tree_RB_REMOVE(&p->p_lwp_tree, lp);
929 KKASSERT(p->p_nthreads == 0);
932 * Don't do anything really bad until all references
933 * to the process go away. This may include other
934 * LWPs which are still in the process of being
935 * reaped. We can't just pull the rug out from under
936 * them because they may still be using the VM space.
938 * Certain kernel facilities such as /proc will also
939 * put a hold on the process for short periods of
943 PSTALL(p, "reap3", 0);
945 /* Take care of our return values. */
949 *status = p->p_xstat;
953 * If we got the child via a ptrace 'attach',
954 * we need to give it back to the old parent.
956 if (p->p_oppid && (t = pfind(p->p_oppid)) != NULL) {
964 lwkt_reltoken(&p->p_token);
970 * Unlink the proc from its process group so that
971 * the following operations won't lead to an
972 * inconsistent state for processes running down
975 proc_remove_zombie(p);
976 lwkt_reltoken(&p->p_token);
980 ruadd(&q->p_cru, &p->p_ru);
983 * Decrement the count of procs running with this uid.
985 chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
988 * Free up credentials.
994 * Remove unused arguments
998 if (pa && refcount_release(&pa->ar_ref)) {
1004 p->p_sigacts = NULL;
1005 if (ps && refcount_release(&ps->ps_refcnt)) {
1006 kfree(ps, M_SUBPROC);
1011 * Our exitingcount was incremented when the process
1012 * became a zombie, now that the process has been
1013 * removed from (almost) all lists we should be able
1014 * to safely destroy its vmspace. Wait for any current
1015 * holders to go away (so the vmspace remains stable),
1018 PSTALL(p, "reap4", 0);
1019 vmspace_exitfree(p);
1020 PSTALL(p, "reap5", 0);
1023 * NOTE: We have to officially release ZOMB in order
1024 * to ensure that a racing thread in kern_wait()
1025 * which blocked on ZOMB is woken up.
1030 atomic_add_int(&nprocs, -1);
1034 if (p->p_stat == SSTOP && (p->p_flags & P_WAITED) == 0 &&
1035 ((p->p_flags & P_TRACED) || (options & WUNTRACED))) {
1037 lwkt_gettoken(&p->p_token);
1038 if (p->p_pptr != q) {
1039 lwkt_reltoken(&p->p_token);
1043 if (p->p_stat != SSTOP ||
1044 (p->p_flags & P_WAITED) != 0 ||
1045 ((p->p_flags & P_TRACED) == 0 &&
1046 (options & WUNTRACED) == 0)) {
1047 lwkt_reltoken(&p->p_token);
1052 p->p_flags |= P_WAITED;
1056 *status = W_STOPCODE(p->p_xstat);
1057 /* Zero rusage so we get something consistent. */
1059 bzero(rusage, sizeof(*rusage));
1061 lwkt_reltoken(&p->p_token);
1065 if ((options & WCONTINUED) && (p->p_flags & P_CONTINUED)) {
1067 lwkt_gettoken(&p->p_token);
1068 if (p->p_pptr != q) {
1069 lwkt_reltoken(&p->p_token);
1073 if ((p->p_flags & P_CONTINUED) == 0) {
1074 lwkt_reltoken(&p->p_token);
1080 p->p_flags &= ~P_CONTINUED;
1085 lwkt_reltoken(&p->p_token);
1094 if (options & WNOHANG) {
1101 * Wait for signal - interlocked using q->p_token.
1103 error = tsleep(q, PCATCH, "wait", 0);
1106 lwkt_reltoken(&q->p_token);
1113 * Change child's parent process to parent.
1115 * p_children/p_sibling requires the parent's token, and
1116 * changing pptr requires the child's token, so we have to
1117 * get three tokens to do this operation. We also need to
1118 * hold pointers that might get ripped out from under us to
1119 * preserve structural integrity.
1121 * It is possible to race another reparent or disconnect or other
1122 * similar operation. We must retry when this situation occurs.
1123 * Once we successfully reparent the process we no longer care
1127 proc_reparent(struct proc *child, struct proc *parent)
1132 while ((opp = child->p_pptr) != parent) {
1134 lwkt_gettoken(&opp->p_token);
1135 lwkt_gettoken(&child->p_token);
1136 lwkt_gettoken(&parent->p_token);
1137 if (child->p_pptr != opp) {
1138 lwkt_reltoken(&parent->p_token);
1139 lwkt_reltoken(&child->p_token);
1140 lwkt_reltoken(&opp->p_token);
1144 LIST_REMOVE(child, p_sibling);
1145 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
1146 child->p_pptr = parent;
1147 lwkt_reltoken(&parent->p_token);
1148 lwkt_reltoken(&child->p_token);
1149 lwkt_reltoken(&opp->p_token);
1150 if (LIST_EMPTY(&opp->p_children))
1159 * The next two functions are to handle adding/deleting items on the
1163 * Take the arguments given and put them onto the exit callout list,
1164 * However first make sure that it's not already there.
1165 * returns 0 on success.
1169 at_exit(exitlist_fn function)
1171 struct exitlist *ep;
1174 /* Be noisy if the programmer has lost track of things */
1175 if (rm_at_exit(function))
1176 kprintf("WARNING: exit callout entry (%p) already present\n",
1179 ep = kmalloc(sizeof(*ep), M_ATEXIT, M_NOWAIT);
1182 ep->function = function;
1183 TAILQ_INSERT_TAIL(&exit_list, ep, next);
1188 * Scan the exit callout list for the given item and remove it.
1189 * Returns the number of items removed (0 or 1)
1192 rm_at_exit(exitlist_fn function)
1194 struct exitlist *ep;
1196 TAILQ_FOREACH(ep, &exit_list, next) {
1197 if (ep->function == function) {
1198 TAILQ_REMOVE(&exit_list, ep, next);
1199 kfree(ep, M_ATEXIT);
1207 * LWP reaper related code.
1210 reaplwps(void *context, int dummy)
1212 struct lwplist *lwplist = context;
1215 lwkt_gettoken(&deadlwp_token);
1216 while ((lp = LIST_FIRST(lwplist))) {
1217 LIST_REMOVE(lp, u.lwp_reap_entry);
1220 lwkt_reltoken(&deadlwp_token);
1224 reaplwp(struct lwp *lp)
1226 while (lwp_wait(lp) == 0)
1236 for (cpu = 0; cpu < ncpus; cpu++) {
1237 LIST_INIT(&deadlwp_list[cpu]);
1238 deadlwp_task[cpu] = kmalloc(sizeof(*deadlwp_task[cpu]),
1239 M_DEVBUF, M_WAITOK);
1240 TASK_INIT(deadlwp_task[cpu], 0, reaplwps, &deadlwp_list[cpu]);
1244 SYSINIT(deadlwpinit, SI_SUB_CONFIGURE, SI_ORDER_ANY, deadlwp_init, NULL);