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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 $
40 * $DragonFly: src/sys/kern/kern_exit.c,v 1.63 2006/09/19 11:47:35 corecode Exp $
43 #include "opt_compat.h"
44 #include "opt_ktrace.h"
46 #include <sys/param.h>
47 #include <sys/systm.h>
48 #include <sys/sysproto.h>
49 #include <sys/kernel.h>
50 #include <sys/malloc.h>
52 #include <sys/ktrace.h>
53 #include <sys/pioctl.h>
56 #include <sys/vnode.h>
57 #include <sys/resourcevar.h>
58 #include <sys/signalvar.h>
59 #include <sys/ptrace.h>
60 #include <sys/acct.h> /* for acct_process() function prototype */
61 #include <sys/filedesc.h>
66 #include <sys/kern_syscall.h>
67 #include <sys/upcall.h>
71 #include <vm/vm_param.h>
74 #include <vm/vm_map.h>
75 #include <vm/vm_zone.h>
76 #include <vm/vm_extern.h>
79 #include <sys/thread2.h>
81 static MALLOC_DEFINE(M_ATEXIT, "atexit", "atexit callback");
82 static MALLOC_DEFINE(M_ZOMBIE, "zombie", "zombie proc status");
85 * callout list for things to do at exit time
89 TAILQ_ENTRY(exitlist) next;
92 TAILQ_HEAD(exit_list_head, exitlist);
93 static struct exit_list_head exit_list = TAILQ_HEAD_INITIALIZER(exit_list);
99 * SYS_EXIT_ARGS(int rval)
102 sys_exit(struct exit_args *uap)
104 exit1(W_EXITCODE(uap->rval, 0));
109 * Exit: deallocate address space and other resources, change proc state
110 * to zombie, and unlink proc from allproc and parent's lists. Save exit
111 * status and rusage for wait(). Check for child processes and orphan them.
116 struct thread *td = curthread;
117 struct proc *p = td->td_proc;
118 struct lwp *lp = td->td_lwp;
125 printf("init died (signal %d, exit %d)\n",
126 WTERMSIG(rv), WEXITSTATUS(rv));
127 panic("Going nowhere without my init!");
130 /* XXX lwp kill other threads */
132 caps_exit(lp->lwp_thread);
135 /* are we a task leader? */
136 if(p == p->p_leader) {
137 struct kill_args killArgs;
138 killArgs.signum = SIGKILL;
141 killArgs.pid = q->p_pid;
143 * The interface for kill is better
144 * than the internal signal
151 tsleep((caddr_t)p, 0, "exit1", 0);
157 STOPEVENT(p, S_EXIT, rv);
158 wakeup(&p->p_stype); /* Wakeup anyone in procfs' PIOCWAIT */
161 * Check if any loadable modules need anything done at process exit.
162 * e.g. SYSV IPC stuff
163 * XXX what if one of these generates an error?
165 TAILQ_FOREACH(ep, &exit_list, next)
168 if (p->p_flag & P_PROFIL)
170 MALLOC(p->p_ru, struct rusage *, sizeof(struct rusage),
173 * If parent is waiting for us to exit or exec,
174 * P_PPWAIT is set; we will wakeup the parent below.
176 p->p_flag &= ~(P_TRACED | P_PPWAIT);
177 p->p_flag |= P_WEXIT;
178 SIGEMPTYSET(p->p_siglist);
179 if (timevalisset(&p->p_realtimer.it_value))
180 callout_stop(&p->p_ithandle);
183 * Reset any sigio structures pointing to us as a result of
184 * F_SETOWN with our pid.
186 funsetownlst(&p->p_sigiolst);
189 * Close open files and release open-file table.
195 if(p->p_leader->p_peers) {
197 while(q->p_peers != p)
199 q->p_peers = p->p_peers;
200 wakeup((caddr_t)p->p_leader);
204 * XXX Shutdown SYSV semaphores
208 KKASSERT(p->p_numposixlocks == 0);
210 /* The next two chunks should probably be moved to vmspace_exit. */
214 * Release upcalls associated with this process
217 upc_release(vm, &p->p_lwp);
219 /* clean up data related to virtual kernel operation */
221 vkernel_drop(p->p_vkernel);
226 * Release user portion of address space.
227 * This releases references to vnodes,
228 * which could cause I/O if the file has been unlinked.
229 * Need to do this early enough that we can still sleep.
230 * Can't free the entire vmspace as the kernel stack
231 * may be mapped within that space also.
233 * Processes sharing the same vmspace may exit in one order, and
234 * get cleaned up by vmspace_exit() in a different order. The
235 * last exiting process to reach this point releases as much of
236 * the environment as it can, and the last process cleaned up
237 * by vmspace_exit() (which decrements exitingcnt) cleans up the
241 if (--vm->vm_refcnt == 0) {
243 pmap_remove_pages(vmspace_pmap(vm), VM_MIN_ADDRESS,
245 (void) vm_map_remove(&vm->vm_map, VM_MIN_ADDRESS,
249 if (SESS_LEADER(p)) {
250 struct session *sp = p->p_session;
255 * We are the controlling process. Signal the
256 * foreground process group, drain the controlling
257 * terminal, and revoke access to the controlling
260 * NOTE: while waiting for the process group to exit
261 * it is possible that one of the processes in the
262 * group will revoke the tty, so we have to recheck.
264 if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) {
265 if (sp->s_ttyp->t_pgrp)
266 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1);
267 (void) ttywait(sp->s_ttyp);
269 * The tty could have been revoked
272 if ((vp = sp->s_ttyvp) != NULL) {
273 ttyclosesession(sp, 0);
275 VOP_REVOKE(vp, REVOKEALL);
277 vrele(vp); /* s_ttyvp ref */
281 * Release the tty. If someone has it open via
282 * /dev/tty then close it (since they no longer can
283 * once we've NULL'd it out).
286 ttyclosesession(sp, 1);
288 * s_ttyp is not zero'd; we use this to indicate
289 * that the session once had a controlling terminal.
290 * (for logging and informational purposes)
295 fixjobc(p, p->p_pgrp, 0);
296 (void)acct_process(p);
302 ktrdestroy(&p->p_tracenode);
306 * Release reference to text vnode
308 if ((vtmp = p->p_textvp) != NULL) {
314 * Move the process to the zombie list. This will block
315 * until the process p_lock count reaches 0. The process will
316 * not be reaped until TDF_EXITING is set by cpu_thread_exit(),
317 * which is called from cpu_proc_exit().
319 proc_move_allproc_zombie(p);
321 q = LIST_FIRST(&p->p_children);
322 if (q) /* only need this if any child is S_ZOMB */
323 wakeup((caddr_t) initproc);
324 for (; q != 0; q = nq) {
325 nq = LIST_NEXT(q, p_sibling);
326 LIST_REMOVE(q, p_sibling);
327 LIST_INSERT_HEAD(&initproc->p_children, q, p_sibling);
328 q->p_pptr = initproc;
329 q->p_sigparent = SIGCHLD;
331 * Traced processes are killed
332 * since their existence means someone is screwing up.
334 if (q->p_flag & P_TRACED) {
335 q->p_flag &= ~P_TRACED;
341 * Save exit status and final rusage info, adding in child rusage
342 * info and self times.
345 *p->p_ru = p->p_stats->p_ru;
346 calcru(p, &p->p_ru->ru_utime, &p->p_ru->ru_stime, NULL);
347 ruadd(p->p_ru, &p->p_stats->p_cru);
350 * notify interested parties of our demise.
352 KNOTE(&p->p_klist, NOTE_EXIT);
355 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT
356 * flag set, notify process 1 instead (and hope it will handle
359 if (p->p_pptr->p_procsig->ps_flag & PS_NOCLDWAIT) {
360 struct proc *pp = p->p_pptr;
361 proc_reparent(p, initproc);
363 * If this was the last child of our parent, notify
364 * parent, so in case he was wait(2)ing, he will
367 if (LIST_EMPTY(&pp->p_children))
371 if (p->p_sigparent && p->p_pptr != initproc) {
372 ksignal(p->p_pptr, p->p_sigparent);
374 ksignal(p->p_pptr, SIGCHLD);
377 wakeup((caddr_t)p->p_pptr);
379 * cpu_exit is responsible for clearing curproc, since
380 * it is heavily integrated with the thread/switching sequence.
382 * Other substructures are freed from wait().
384 plimit_free(&p->p_limit);
387 * Release the current user process designation on the process so
388 * the userland scheduler can work in someone else.
390 p->p_usched->release_curproc(lp);
393 * Finally, call machine-dependent code to release the remaining
394 * resources including address space, the kernel stack and pcb.
395 * The address space is released by "vmspace_free(p->p_vmspace)";
396 * This is machine-dependent, as we may have to change stacks
397 * or ensure that the current one isn't reallocated before we
398 * finish. cpu_exit will end with a call to cpu_switch(), finishing
399 * our execution (pun intended).
405 sys_wait4(struct wait_args *uap)
407 struct rusage rusage;
410 error = kern_wait(uap->pid, uap->status ? &status : NULL,
411 uap->options, uap->rusage ? &rusage : NULL, &uap->sysmsg_fds[0]);
413 if (error == 0 && uap->status)
414 error = copyout(&status, uap->status, sizeof(*uap->status));
415 if (error == 0 && uap->rusage)
416 error = copyout(&rusage, uap->rusage, sizeof(*uap->rusage));
423 * wait_args(int pid, int *status, int options, struct rusage *rusage)
426 kern_wait(pid_t pid, int *status, int options, struct rusage *rusage, int *res)
428 struct thread *td = curthread;
429 struct thread *deadtd;
430 struct proc *q = td->td_proc;
436 if (options &~ (WUNTRACED|WNOHANG|WLINUXCLONE))
440 * Hack for backwards compatibility with badly written user code.
441 * Or perhaps we have to do this anyway, it is unclear. XXX
443 * The problem is that if a process group is stopped and the parent
444 * is doing a wait*(..., WUNTRACED, ...), it will see the STOP
445 * of the child and then stop itself when it tries to return from the
446 * system call. When the process group is resumed the parent will
447 * then get the STOP status even though the child has now resumed
448 * (a followup wait*() will get the CONT status).
450 * Previously the CONT would overwrite the STOP because the tstop
451 * was handled within tsleep(), and the parent would only see
452 * the CONT when both are stopped and continued together. This litte
453 * two-line hack restores this effect.
455 while (q->p_flag & P_STOPPED)
459 LIST_FOREACH(p, &q->p_children, p_sibling) {
460 if (pid != WAIT_ANY &&
461 p->p_pid != pid && p->p_pgid != -pid)
464 /* This special case handles a kthread spawned by linux_clone
465 * (see linux_misc.c). The linux_wait4 and linux_waitpid
466 * functions need to be able to distinguish between waiting
467 * on a process and waiting on a thread. It is a thread if
468 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
469 * signifies we want to wait for threads and not processes.
471 if ((p->p_sigparent != SIGCHLD) ^
472 ((options & WLINUXCLONE) != 0)) {
477 if (p->p_flag & P_ZOMBIE) {
478 KKASSERT((p->p_nthreads == 1));
479 deadtd = LIST_FIRST(&p->p_lwps)->lwp_thread;
482 * Other kernel threads may be in the middle of
483 * accessing the proc. For example, kern/kern_proc.c
484 * could be blocked writing proc data to a sysctl.
485 * At the moment, if this occurs, we are not woken
486 * up and rely on a one-second retry.
490 tsleep(p, 0, "reap3", hz);
492 lwkt_wait_free(deadtd);
495 * The process's thread may still be in the middle
496 * of switching away, we can't rip its stack out from
497 * under it until TDF_EXITING is set and both
498 * TDF_RUNNING and TDF_PREEMPT_LOCK are clear.
499 * TDF_PREEMPT_LOCK must be checked because TDF_RUNNING
500 * will be cleared temporarily if a thread gets
503 * YYY no wakeup occurs so we depend on the timeout.
505 if ((deadtd->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK|TDF_EXITING)) != TDF_EXITING) {
506 tsleep(deadtd, 0, "reap2", 1);
510 /* scheduling hook for heuristic */
511 p->p_usched->heuristic_exiting(td->td_lwp, deadtd->td_lwp);
513 /* Take care of our return values. */
516 *status = p->p_xstat;
520 * If we got the child via a ptrace 'attach',
521 * we need to give it back to the old parent.
523 if (p->p_oppid && (t = pfind(p->p_oppid))) {
531 ruadd(&q->p_stats->p_cru, p->p_ru);
532 FREE(p->p_ru, M_ZOMBIE);
536 * Decrement the count of procs running with this uid.
538 chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
541 * Free up credentials.
547 * Remove unused arguments
549 if (p->p_args && --p->p_args->ar_ref == 0)
550 FREE(p->p_args, M_PARGS);
553 * Finally finished with old proc entry.
554 * Unlink it from its process group and free it.
557 proc_remove_zombie(p);
559 if (--p->p_procsig->ps_refcnt == 0) {
560 if (p->p_sigacts != &p->p_addr->u_sigacts)
561 FREE(p->p_sigacts, M_SUBPROC);
562 FREE(p->p_procsig, M_SUBPROC);
571 if ((p->p_flag & P_STOPPED) && (p->p_flag & P_WAITED) == 0 &&
572 (p->p_flag & P_TRACED || options & WUNTRACED)) {
573 p->p_flag |= P_WAITED;
577 *status = W_STOPCODE(p->p_xstat);
578 /* Zero rusage so we get something consistent. */
580 bzero(rusage, sizeof(rusage));
586 if (options & WNOHANG) {
590 error = tsleep((caddr_t)q, PCATCH, "wait", 0);
597 * make process 'parent' the new parent of process 'child'.
600 proc_reparent(struct proc *child, struct proc *parent)
603 if (child->p_pptr == parent)
606 LIST_REMOVE(child, p_sibling);
607 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
608 child->p_pptr = parent;
612 * The next two functions are to handle adding/deleting items on the
616 * Take the arguments given and put them onto the exit callout list,
617 * However first make sure that it's not already there.
618 * returns 0 on success.
622 at_exit(exitlist_fn function)
627 /* Be noisy if the programmer has lost track of things */
628 if (rm_at_exit(function))
629 printf("WARNING: exit callout entry (%p) already present\n",
632 ep = kmalloc(sizeof(*ep), M_ATEXIT, M_NOWAIT);
635 ep->function = function;
636 TAILQ_INSERT_TAIL(&exit_list, ep, next);
641 * Scan the exit callout list for the given item and remove it.
642 * Returns the number of items removed (0 or 1)
645 rm_at_exit(exitlist_fn function)
649 TAILQ_FOREACH(ep, &exit_list, next) {
650 if (ep->function == function) {
651 TAILQ_REMOVE(&exit_list, ep, next);
662 struct proc *p = curproc;
665 if (p->p_procsig->ps_refcnt == 1 &&
666 p->p_sigacts != &p->p_addr->u_sigacts) {
669 p->p_addr->u_sigacts = *pss;
670 p->p_sigacts = &p->p_addr->u_sigacts;
672 FREE(pss, M_SUBPROC);