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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 1.67 2007/01/01 22:51:17 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 kprintf("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)
171 * If parent is waiting for us to exit or exec,
172 * P_PPWAIT is set; we will wakeup the parent below.
174 p->p_flag &= ~(P_TRACED | P_PPWAIT);
175 p->p_flag |= P_WEXIT;
176 SIGEMPTYSET(p->p_siglist);
177 if (timevalisset(&p->p_realtimer.it_value))
178 callout_stop(&p->p_ithandle);
181 * Reset any sigio structures pointing to us as a result of
182 * F_SETOWN with our pid.
184 funsetownlst(&p->p_sigiolst);
187 * Close open files and release open-file table.
193 if(p->p_leader->p_peers) {
195 while(q->p_peers != p)
197 q->p_peers = p->p_peers;
198 wakeup((caddr_t)p->p_leader);
202 * XXX Shutdown SYSV semaphores
206 KKASSERT(p->p_numposixlocks == 0);
208 /* The next two chunks should probably be moved to vmspace_exit. */
212 * Release upcalls associated with this process
215 upc_release(vm, &p->p_lwp);
217 /* clean up data related to virtual kernel operation */
222 * Release user portion of address space.
223 * This releases references to vnodes,
224 * which could cause I/O if the file has been unlinked.
225 * Need to do this early enough that we can still sleep.
226 * Can't free the entire vmspace as the kernel stack
227 * may be mapped within that space also.
229 * Processes sharing the same vmspace may exit in one order, and
230 * get cleaned up by vmspace_exit() in a different order. The
231 * last exiting process to reach this point releases as much of
232 * the environment as it can, and the last process cleaned up
233 * by vmspace_exit() (which decrements exitingcnt) cleans up the
237 if (--vm->vm_refcnt == 0) {
239 pmap_remove_pages(vmspace_pmap(vm), VM_MIN_USER_ADDRESS,
240 VM_MAX_USER_ADDRESS);
241 vm_map_remove(&vm->vm_map, VM_MIN_USER_ADDRESS,
242 VM_MAX_USER_ADDRESS);
245 if (SESS_LEADER(p)) {
246 struct session *sp = p->p_session;
251 * We are the controlling process. Signal the
252 * foreground process group, drain the controlling
253 * terminal, and revoke access to the controlling
256 * NOTE: while waiting for the process group to exit
257 * it is possible that one of the processes in the
258 * group will revoke the tty, so we have to recheck.
260 if (sp->s_ttyp && (sp->s_ttyp->t_session == sp)) {
261 if (sp->s_ttyp->t_pgrp)
262 pgsignal(sp->s_ttyp->t_pgrp, SIGHUP, 1);
263 (void) ttywait(sp->s_ttyp);
265 * The tty could have been revoked
268 if ((vp = sp->s_ttyvp) != NULL) {
269 ttyclosesession(sp, 0);
271 VOP_REVOKE(vp, REVOKEALL);
273 vrele(vp); /* s_ttyvp ref */
277 * Release the tty. If someone has it open via
278 * /dev/tty then close it (since they no longer can
279 * once we've NULL'd it out).
282 ttyclosesession(sp, 1);
284 * s_ttyp is not zero'd; we use this to indicate
285 * that the session once had a controlling terminal.
286 * (for logging and informational purposes)
291 fixjobc(p, p->p_pgrp, 0);
292 (void)acct_process(p);
298 ktrdestroy(&p->p_tracenode);
302 * Release reference to text vnode
304 if ((vtmp = p->p_textvp) != NULL) {
310 * Move the process to the zombie list. This will block
311 * until the process p_lock count reaches 0. The process will
312 * not be reaped until TDF_EXITING is set by cpu_thread_exit(),
313 * which is called from cpu_proc_exit().
315 proc_move_allproc_zombie(p);
317 q = LIST_FIRST(&p->p_children);
318 if (q) /* only need this if any child is S_ZOMB */
319 wakeup((caddr_t) initproc);
320 for (; q != 0; q = nq) {
321 nq = LIST_NEXT(q, p_sibling);
322 LIST_REMOVE(q, p_sibling);
323 LIST_INSERT_HEAD(&initproc->p_children, q, p_sibling);
324 q->p_pptr = initproc;
325 q->p_sigparent = SIGCHLD;
327 * Traced processes are killed
328 * since their existence means someone is screwing up.
330 if (q->p_flag & P_TRACED) {
331 q->p_flag &= ~P_TRACED;
337 * Save exit status and final rusage info, adding in child rusage
338 * info and self times.
341 calcru_proc(p, &p->p_ru);
342 ruadd(&p->p_ru, &p->p_cru);
345 * notify interested parties of our demise.
347 KNOTE(&p->p_klist, NOTE_EXIT);
350 * Notify parent that we're gone. If parent has the PS_NOCLDWAIT
351 * flag set, notify process 1 instead (and hope it will handle
354 if (p->p_pptr->p_procsig->ps_flag & PS_NOCLDWAIT) {
355 struct proc *pp = p->p_pptr;
356 proc_reparent(p, initproc);
358 * If this was the last child of our parent, notify
359 * parent, so in case he was wait(2)ing, he will
362 if (LIST_EMPTY(&pp->p_children))
366 if (p->p_sigparent && p->p_pptr != initproc) {
367 ksignal(p->p_pptr, p->p_sigparent);
369 ksignal(p->p_pptr, SIGCHLD);
372 wakeup((caddr_t)p->p_pptr);
374 * cpu_exit is responsible for clearing curproc, since
375 * it is heavily integrated with the thread/switching sequence.
377 * Other substructures are freed from wait().
379 plimit_free(&p->p_limit);
382 * Release the current user process designation on the process so
383 * the userland scheduler can work in someone else.
385 p->p_usched->release_curproc(lp);
388 * Finally, call machine-dependent code to release the remaining
389 * resources including address space, the kernel stack and pcb.
390 * The address space is released by "vmspace_free(p->p_vmspace)";
391 * This is machine-dependent, as we may have to change stacks
392 * or ensure that the current one isn't reallocated before we
393 * finish. cpu_exit will end with a call to cpu_switch(), finishing
394 * our execution (pun intended).
400 sys_wait4(struct wait_args *uap)
402 struct rusage rusage;
405 error = kern_wait(uap->pid, uap->status ? &status : NULL,
406 uap->options, uap->rusage ? &rusage : NULL, &uap->sysmsg_fds[0]);
408 if (error == 0 && uap->status)
409 error = copyout(&status, uap->status, sizeof(*uap->status));
410 if (error == 0 && uap->rusage)
411 error = copyout(&rusage, uap->rusage, sizeof(*uap->rusage));
418 * wait_args(int pid, int *status, int options, struct rusage *rusage)
421 kern_wait(pid_t pid, int *status, int options, struct rusage *rusage, int *res)
423 struct thread *td = curthread;
424 struct thread *deadtd;
425 struct proc *q = td->td_proc;
431 if (options &~ (WUNTRACED|WNOHANG|WLINUXCLONE))
435 * Hack for backwards compatibility with badly written user code.
436 * Or perhaps we have to do this anyway, it is unclear. XXX
438 * The problem is that if a process group is stopped and the parent
439 * is doing a wait*(..., WUNTRACED, ...), it will see the STOP
440 * of the child and then stop itself when it tries to return from the
441 * system call. When the process group is resumed the parent will
442 * then get the STOP status even though the child has now resumed
443 * (a followup wait*() will get the CONT status).
445 * Previously the CONT would overwrite the STOP because the tstop
446 * was handled within tsleep(), and the parent would only see
447 * the CONT when both are stopped and continued together. This litte
448 * two-line hack restores this effect.
450 while (q->p_flag & P_STOPPED)
454 LIST_FOREACH(p, &q->p_children, p_sibling) {
455 if (pid != WAIT_ANY &&
456 p->p_pid != pid && p->p_pgid != -pid)
459 /* This special case handles a kthread spawned by linux_clone
460 * (see linux_misc.c). The linux_wait4 and linux_waitpid
461 * functions need to be able to distinguish between waiting
462 * on a process and waiting on a thread. It is a thread if
463 * p_sigparent is not SIGCHLD, and the WLINUXCLONE option
464 * signifies we want to wait for threads and not processes.
466 if ((p->p_sigparent != SIGCHLD) ^
467 ((options & WLINUXCLONE) != 0)) {
472 if (p->p_flag & P_ZOMBIE) {
473 KKASSERT((p->p_nthreads == 1));
474 deadtd = LIST_FIRST(&p->p_lwps)->lwp_thread;
477 * Other kernel threads may be in the middle of
478 * accessing the proc. For example, kern/kern_proc.c
479 * could be blocked writing proc data to a sysctl.
480 * At the moment, if this occurs, we are not woken
481 * up and rely on a one-second retry.
485 tsleep(p, 0, "reap3", hz);
487 lwkt_wait_free(deadtd);
490 * The process's thread may still be in the middle
491 * of switching away, we can't rip its stack out from
492 * under it until TDF_EXITING is set and both
493 * TDF_RUNNING and TDF_PREEMPT_LOCK are clear.
494 * TDF_PREEMPT_LOCK must be checked because TDF_RUNNING
495 * will be cleared temporarily if a thread gets
498 * YYY no wakeup occurs so we depend on the timeout.
500 if ((deadtd->td_flags & (TDF_RUNNING|TDF_PREEMPT_LOCK|TDF_EXITING)) != TDF_EXITING) {
501 tsleep(deadtd, 0, "reap2", 1);
505 /* scheduling hook for heuristic */
506 p->p_usched->heuristic_exiting(td->td_lwp, deadtd->td_lwp);
508 /* Take care of our return values. */
511 *status = p->p_xstat;
515 * If we got the child via a ptrace 'attach',
516 * we need to give it back to the old parent.
518 if (p->p_oppid && (t = pfind(p->p_oppid))) {
526 ruadd(&q->p_cru, &p->p_ru);
529 * Decrement the count of procs running with this uid.
531 chgproccnt(p->p_ucred->cr_ruidinfo, -1, 0);
534 * Free up credentials.
540 * Remove unused arguments
542 if (p->p_args && --p->p_args->ar_ref == 0)
543 FREE(p->p_args, M_PARGS);
546 * Finally finished with old proc entry.
547 * Unlink it from its process group and free it.
550 proc_remove_zombie(p);
552 if (--p->p_procsig->ps_refcnt == 0) {
553 if (p->p_sigacts != &p->p_addr->u_sigacts)
554 FREE(p->p_sigacts, M_SUBPROC);
555 FREE(p->p_procsig, M_SUBPROC);
564 if ((p->p_flag & P_STOPPED) && (p->p_flag & P_WAITED) == 0 &&
565 (p->p_flag & P_TRACED || options & WUNTRACED)) {
566 p->p_flag |= P_WAITED;
570 *status = W_STOPCODE(p->p_xstat);
571 /* Zero rusage so we get something consistent. */
573 bzero(rusage, sizeof(rusage));
579 if (options & WNOHANG) {
583 error = tsleep((caddr_t)q, PCATCH, "wait", 0);
590 * make process 'parent' the new parent of process 'child'.
593 proc_reparent(struct proc *child, struct proc *parent)
596 if (child->p_pptr == parent)
599 LIST_REMOVE(child, p_sibling);
600 LIST_INSERT_HEAD(&parent->p_children, child, p_sibling);
601 child->p_pptr = parent;
605 * The next two functions are to handle adding/deleting items on the
609 * Take the arguments given and put them onto the exit callout list,
610 * However first make sure that it's not already there.
611 * returns 0 on success.
615 at_exit(exitlist_fn function)
620 /* Be noisy if the programmer has lost track of things */
621 if (rm_at_exit(function))
622 kprintf("WARNING: exit callout entry (%p) already present\n",
625 ep = kmalloc(sizeof(*ep), M_ATEXIT, M_NOWAIT);
628 ep->function = function;
629 TAILQ_INSERT_TAIL(&exit_list, ep, next);
634 * Scan the exit callout list for the given item and remove it.
635 * Returns the number of items removed (0 or 1)
638 rm_at_exit(exitlist_fn function)
642 TAILQ_FOREACH(ep, &exit_list, next) {
643 if (ep->function == function) {
644 TAILQ_REMOVE(&exit_list, ep, next);
655 struct proc *p = curproc;
658 if (p->p_procsig->ps_refcnt == 1 &&
659 p->p_sigacts != &p->p_addr->u_sigacts) {
662 p->p_addr->u_sigacts = *pss;
663 p->p_sigacts = &p->p_addr->u_sigacts;
665 FREE(pss, M_SUBPROC);