601263c0806f3f2580b94db235f18a02503e1ff4
[linux-2.6.git] / kernel / exit.c
1 /*
2  *  linux/kernel/exit.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6
7 #include <linux/config.h>
8 #include <linux/mm.h>
9 #include <linux/slab.h>
10 #include <linux/interrupt.h>
11 #include <linux/smp_lock.h>
12 #include <linux/module.h>
13 #include <linux/capability.h>
14 #include <linux/completion.h>
15 #include <linux/personality.h>
16 #include <linux/tty.h>
17 #include <linux/namespace.h>
18 #include <linux/key.h>
19 #include <linux/security.h>
20 #include <linux/cpu.h>
21 #include <linux/acct.h>
22 #include <linux/file.h>
23 #include <linux/binfmts.h>
24 #include <linux/ptrace.h>
25 #include <linux/profile.h>
26 #include <linux/mount.h>
27 #include <linux/proc_fs.h>
28 #include <linux/mempolicy.h>
29 #include <linux/cpuset.h>
30 #include <linux/syscalls.h>
31 #include <linux/signal.h>
32 #include <linux/posix-timers.h>
33 #include <linux/cn_proc.h>
34 #include <linux/mutex.h>
35 #include <linux/futex.h>
36 #include <linux/compat.h>
37 #include <linux/pipe_fs_i.h>
38 #include <linux/audit.h> /* for audit_free() */
39 #include <linux/resource.h>
40
41 #include <asm/uaccess.h>
42 #include <asm/unistd.h>
43 #include <asm/pgtable.h>
44 #include <asm/mmu_context.h>
45
46 extern void sem_exit (void);
47 extern struct task_struct *child_reaper;
48
49 static void exit_mm(struct task_struct * tsk);
50
51 static void __unhash_process(struct task_struct *p)
52 {
53         nr_threads--;
54         detach_pid(p, PIDTYPE_PID);
55         if (thread_group_leader(p)) {
56                 detach_pid(p, PIDTYPE_PGID);
57                 detach_pid(p, PIDTYPE_SID);
58
59                 list_del_rcu(&p->tasks);
60                 __get_cpu_var(process_counts)--;
61         }
62         list_del_rcu(&p->thread_group);
63         remove_parent(p);
64 }
65
66 /*
67  * This function expects the tasklist_lock write-locked.
68  */
69 static void __exit_signal(struct task_struct *tsk)
70 {
71         struct signal_struct *sig = tsk->signal;
72         struct sighand_struct *sighand;
73
74         BUG_ON(!sig);
75         BUG_ON(!atomic_read(&sig->count));
76
77         rcu_read_lock();
78         sighand = rcu_dereference(tsk->sighand);
79         spin_lock(&sighand->siglock);
80
81         posix_cpu_timers_exit(tsk);
82         if (atomic_dec_and_test(&sig->count))
83                 posix_cpu_timers_exit_group(tsk);
84         else {
85                 /*
86                  * If there is any task waiting for the group exit
87                  * then notify it:
88                  */
89                 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
90                         wake_up_process(sig->group_exit_task);
91                         sig->group_exit_task = NULL;
92                 }
93                 if (tsk == sig->curr_target)
94                         sig->curr_target = next_thread(tsk);
95                 /*
96                  * Accumulate here the counters for all threads but the
97                  * group leader as they die, so they can be added into
98                  * the process-wide totals when those are taken.
99                  * The group leader stays around as a zombie as long
100                  * as there are other threads.  When it gets reaped,
101                  * the exit.c code will add its counts into these totals.
102                  * We won't ever get here for the group leader, since it
103                  * will have been the last reference on the signal_struct.
104                  */
105                 sig->utime = cputime_add(sig->utime, tsk->utime);
106                 sig->stime = cputime_add(sig->stime, tsk->stime);
107                 sig->min_flt += tsk->min_flt;
108                 sig->maj_flt += tsk->maj_flt;
109                 sig->nvcsw += tsk->nvcsw;
110                 sig->nivcsw += tsk->nivcsw;
111                 sig->sched_time += tsk->sched_time;
112                 sig = NULL; /* Marker for below. */
113         }
114
115         __unhash_process(tsk);
116
117         tsk->signal = NULL;
118         tsk->sighand = NULL;
119         spin_unlock(&sighand->siglock);
120         rcu_read_unlock();
121
122         __cleanup_sighand(sighand);
123         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
124         flush_sigqueue(&tsk->pending);
125         if (sig) {
126                 flush_sigqueue(&sig->shared_pending);
127                 __cleanup_signal(sig);
128         }
129 }
130
131 static void delayed_put_task_struct(struct rcu_head *rhp)
132 {
133         put_task_struct(container_of(rhp, struct task_struct, rcu));
134 }
135
136 void release_task(struct task_struct * p)
137 {
138         int zap_leader;
139         task_t *leader;
140         struct dentry *proc_dentry;
141
142 repeat:
143         atomic_dec(&p->user->processes);
144         spin_lock(&p->proc_lock);
145         proc_dentry = proc_pid_unhash(p);
146         write_lock_irq(&tasklist_lock);
147         ptrace_unlink(p);
148         BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
149         __exit_signal(p);
150
151         /*
152          * If we are the last non-leader member of the thread
153          * group, and the leader is zombie, then notify the
154          * group leader's parent process. (if it wants notification.)
155          */
156         zap_leader = 0;
157         leader = p->group_leader;
158         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
159                 BUG_ON(leader->exit_signal == -1);
160                 do_notify_parent(leader, leader->exit_signal);
161                 /*
162                  * If we were the last child thread and the leader has
163                  * exited already, and the leader's parent ignores SIGCHLD,
164                  * then we are the one who should release the leader.
165                  *
166                  * do_notify_parent() will have marked it self-reaping in
167                  * that case.
168                  */
169                 zap_leader = (leader->exit_signal == -1);
170         }
171
172         sched_exit(p);
173         write_unlock_irq(&tasklist_lock);
174         spin_unlock(&p->proc_lock);
175         proc_pid_flush(proc_dentry);
176         release_thread(p);
177         call_rcu(&p->rcu, delayed_put_task_struct);
178
179         p = leader;
180         if (unlikely(zap_leader))
181                 goto repeat;
182 }
183
184 /*
185  * This checks not only the pgrp, but falls back on the pid if no
186  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
187  * without this...
188  */
189 int session_of_pgrp(int pgrp)
190 {
191         struct task_struct *p;
192         int sid = -1;
193
194         read_lock(&tasklist_lock);
195         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
196                 if (p->signal->session > 0) {
197                         sid = p->signal->session;
198                         goto out;
199                 }
200         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
201         p = find_task_by_pid(pgrp);
202         if (p)
203                 sid = p->signal->session;
204 out:
205         read_unlock(&tasklist_lock);
206         
207         return sid;
208 }
209
210 /*
211  * Determine if a process group is "orphaned", according to the POSIX
212  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
213  * by terminal-generated stop signals.  Newly orphaned process groups are
214  * to receive a SIGHUP and a SIGCONT.
215  *
216  * "I ask you, have you ever known what it is to be an orphan?"
217  */
218 static int will_become_orphaned_pgrp(int pgrp, task_t *ignored_task)
219 {
220         struct task_struct *p;
221         int ret = 1;
222
223         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
224                 if (p == ignored_task
225                                 || p->exit_state
226                                 || p->real_parent->pid == 1)
227                         continue;
228                 if (process_group(p->real_parent) != pgrp
229                             && p->real_parent->signal->session == p->signal->session) {
230                         ret = 0;
231                         break;
232                 }
233         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
234         return ret;     /* (sighing) "Often!" */
235 }
236
237 int is_orphaned_pgrp(int pgrp)
238 {
239         int retval;
240
241         read_lock(&tasklist_lock);
242         retval = will_become_orphaned_pgrp(pgrp, NULL);
243         read_unlock(&tasklist_lock);
244
245         return retval;
246 }
247
248 static int has_stopped_jobs(int pgrp)
249 {
250         int retval = 0;
251         struct task_struct *p;
252
253         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
254                 if (p->state != TASK_STOPPED)
255                         continue;
256
257                 /* If p is stopped by a debugger on a signal that won't
258                    stop it, then don't count p as stopped.  This isn't
259                    perfect but it's a good approximation.  */
260                 if (unlikely (p->ptrace)
261                     && p->exit_code != SIGSTOP
262                     && p->exit_code != SIGTSTP
263                     && p->exit_code != SIGTTOU
264                     && p->exit_code != SIGTTIN)
265                         continue;
266
267                 retval = 1;
268                 break;
269         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
270         return retval;
271 }
272
273 /**
274  * reparent_to_init - Reparent the calling kernel thread to the init task.
275  *
276  * If a kernel thread is launched as a result of a system call, or if
277  * it ever exits, it should generally reparent itself to init so that
278  * it is correctly cleaned up on exit.
279  *
280  * The various task state such as scheduling policy and priority may have
281  * been inherited from a user process, so we reset them to sane values here.
282  *
283  * NOTE that reparent_to_init() gives the caller full capabilities.
284  */
285 static void reparent_to_init(void)
286 {
287         write_lock_irq(&tasklist_lock);
288
289         ptrace_unlink(current);
290         /* Reparent to init */
291         remove_parent(current);
292         current->parent = child_reaper;
293         current->real_parent = child_reaper;
294         add_parent(current);
295
296         /* Set the exit signal to SIGCHLD so we signal init on exit */
297         current->exit_signal = SIGCHLD;
298
299         if ((current->policy == SCHED_NORMAL ||
300                         current->policy == SCHED_BATCH)
301                                 && (task_nice(current) < 0))
302                 set_user_nice(current, 0);
303         /* cpus_allowed? */
304         /* rt_priority? */
305         /* signals? */
306         security_task_reparent_to_init(current);
307         memcpy(current->signal->rlim, init_task.signal->rlim,
308                sizeof(current->signal->rlim));
309         atomic_inc(&(INIT_USER->__count));
310         write_unlock_irq(&tasklist_lock);
311         switch_uid(INIT_USER);
312 }
313
314 void __set_special_pids(pid_t session, pid_t pgrp)
315 {
316         struct task_struct *curr = current->group_leader;
317
318         if (curr->signal->session != session) {
319                 detach_pid(curr, PIDTYPE_SID);
320                 curr->signal->session = session;
321                 attach_pid(curr, PIDTYPE_SID, session);
322         }
323         if (process_group(curr) != pgrp) {
324                 detach_pid(curr, PIDTYPE_PGID);
325                 curr->signal->pgrp = pgrp;
326                 attach_pid(curr, PIDTYPE_PGID, pgrp);
327         }
328 }
329
330 void set_special_pids(pid_t session, pid_t pgrp)
331 {
332         write_lock_irq(&tasklist_lock);
333         __set_special_pids(session, pgrp);
334         write_unlock_irq(&tasklist_lock);
335 }
336
337 /*
338  * Let kernel threads use this to say that they
339  * allow a certain signal (since daemonize() will
340  * have disabled all of them by default).
341  */
342 int allow_signal(int sig)
343 {
344         if (!valid_signal(sig) || sig < 1)
345                 return -EINVAL;
346
347         spin_lock_irq(&current->sighand->siglock);
348         sigdelset(&current->blocked, sig);
349         if (!current->mm) {
350                 /* Kernel threads handle their own signals.
351                    Let the signal code know it'll be handled, so
352                    that they don't get converted to SIGKILL or
353                    just silently dropped */
354                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
355         }
356         recalc_sigpending();
357         spin_unlock_irq(&current->sighand->siglock);
358         return 0;
359 }
360
361 EXPORT_SYMBOL(allow_signal);
362
363 int disallow_signal(int sig)
364 {
365         if (!valid_signal(sig) || sig < 1)
366                 return -EINVAL;
367
368         spin_lock_irq(&current->sighand->siglock);
369         sigaddset(&current->blocked, sig);
370         recalc_sigpending();
371         spin_unlock_irq(&current->sighand->siglock);
372         return 0;
373 }
374
375 EXPORT_SYMBOL(disallow_signal);
376
377 /*
378  *      Put all the gunge required to become a kernel thread without
379  *      attached user resources in one place where it belongs.
380  */
381
382 void daemonize(const char *name, ...)
383 {
384         va_list args;
385         struct fs_struct *fs;
386         sigset_t blocked;
387
388         va_start(args, name);
389         vsnprintf(current->comm, sizeof(current->comm), name, args);
390         va_end(args);
391
392         /*
393          * If we were started as result of loading a module, close all of the
394          * user space pages.  We don't need them, and if we didn't close them
395          * they would be locked into memory.
396          */
397         exit_mm(current);
398
399         set_special_pids(1, 1);
400         mutex_lock(&tty_mutex);
401         current->signal->tty = NULL;
402         mutex_unlock(&tty_mutex);
403
404         /* Block and flush all signals */
405         sigfillset(&blocked);
406         sigprocmask(SIG_BLOCK, &blocked, NULL);
407         flush_signals(current);
408
409         /* Become as one with the init task */
410
411         exit_fs(current);       /* current->fs->count--; */
412         fs = init_task.fs;
413         current->fs = fs;
414         atomic_inc(&fs->count);
415         exit_namespace(current);
416         current->namespace = init_task.namespace;
417         get_namespace(current->namespace);
418         exit_files(current);
419         current->files = init_task.files;
420         atomic_inc(&current->files->count);
421
422         reparent_to_init();
423 }
424
425 EXPORT_SYMBOL(daemonize);
426
427 static void close_files(struct files_struct * files)
428 {
429         int i, j;
430         struct fdtable *fdt;
431
432         j = 0;
433
434         /*
435          * It is safe to dereference the fd table without RCU or
436          * ->file_lock because this is the last reference to the
437          * files structure.
438          */
439         fdt = files_fdtable(files);
440         for (;;) {
441                 unsigned long set;
442                 i = j * __NFDBITS;
443                 if (i >= fdt->max_fdset || i >= fdt->max_fds)
444                         break;
445                 set = fdt->open_fds->fds_bits[j++];
446                 while (set) {
447                         if (set & 1) {
448                                 struct file * file = xchg(&fdt->fd[i], NULL);
449                                 if (file)
450                                         filp_close(file, files);
451                         }
452                         i++;
453                         set >>= 1;
454                 }
455         }
456 }
457
458 struct files_struct *get_files_struct(struct task_struct *task)
459 {
460         struct files_struct *files;
461
462         task_lock(task);
463         files = task->files;
464         if (files)
465                 atomic_inc(&files->count);
466         task_unlock(task);
467
468         return files;
469 }
470
471 void fastcall put_files_struct(struct files_struct *files)
472 {
473         struct fdtable *fdt;
474
475         if (atomic_dec_and_test(&files->count)) {
476                 close_files(files);
477                 /*
478                  * Free the fd and fdset arrays if we expanded them.
479                  * If the fdtable was embedded, pass files for freeing
480                  * at the end of the RCU grace period. Otherwise,
481                  * you can free files immediately.
482                  */
483                 fdt = files_fdtable(files);
484                 if (fdt == &files->fdtab)
485                         fdt->free_files = files;
486                 else
487                         kmem_cache_free(files_cachep, files);
488                 free_fdtable(fdt);
489         }
490 }
491
492 EXPORT_SYMBOL(put_files_struct);
493
494 static inline void __exit_files(struct task_struct *tsk)
495 {
496         struct files_struct * files = tsk->files;
497
498         if (files) {
499                 task_lock(tsk);
500                 tsk->files = NULL;
501                 task_unlock(tsk);
502                 put_files_struct(files);
503         }
504 }
505
506 void exit_files(struct task_struct *tsk)
507 {
508         __exit_files(tsk);
509 }
510
511 static inline void __put_fs_struct(struct fs_struct *fs)
512 {
513         /* No need to hold fs->lock if we are killing it */
514         if (atomic_dec_and_test(&fs->count)) {
515                 dput(fs->root);
516                 mntput(fs->rootmnt);
517                 dput(fs->pwd);
518                 mntput(fs->pwdmnt);
519                 if (fs->altroot) {
520                         dput(fs->altroot);
521                         mntput(fs->altrootmnt);
522                 }
523                 kmem_cache_free(fs_cachep, fs);
524         }
525 }
526
527 void put_fs_struct(struct fs_struct *fs)
528 {
529         __put_fs_struct(fs);
530 }
531
532 static inline void __exit_fs(struct task_struct *tsk)
533 {
534         struct fs_struct * fs = tsk->fs;
535
536         if (fs) {
537                 task_lock(tsk);
538                 tsk->fs = NULL;
539                 task_unlock(tsk);
540                 __put_fs_struct(fs);
541         }
542 }
543
544 void exit_fs(struct task_struct *tsk)
545 {
546         __exit_fs(tsk);
547 }
548
549 EXPORT_SYMBOL_GPL(exit_fs);
550
551 /*
552  * Turn us into a lazy TLB process if we
553  * aren't already..
554  */
555 static void exit_mm(struct task_struct * tsk)
556 {
557         struct mm_struct *mm = tsk->mm;
558
559         mm_release(tsk, mm);
560         if (!mm)
561                 return;
562         /*
563          * Serialize with any possible pending coredump.
564          * We must hold mmap_sem around checking core_waiters
565          * and clearing tsk->mm.  The core-inducing thread
566          * will increment core_waiters for each thread in the
567          * group with ->mm != NULL.
568          */
569         down_read(&mm->mmap_sem);
570         if (mm->core_waiters) {
571                 up_read(&mm->mmap_sem);
572                 down_write(&mm->mmap_sem);
573                 if (!--mm->core_waiters)
574                         complete(mm->core_startup_done);
575                 up_write(&mm->mmap_sem);
576
577                 wait_for_completion(&mm->core_done);
578                 down_read(&mm->mmap_sem);
579         }
580         atomic_inc(&mm->mm_count);
581         BUG_ON(mm != tsk->active_mm);
582         /* more a memory barrier than a real lock */
583         task_lock(tsk);
584         tsk->mm = NULL;
585         up_read(&mm->mmap_sem);
586         enter_lazy_tlb(mm, current);
587         task_unlock(tsk);
588         mmput(mm);
589 }
590
591 static inline void choose_new_parent(task_t *p, task_t *reaper)
592 {
593         /*
594          * Make sure we're not reparenting to ourselves and that
595          * the parent is not a zombie.
596          */
597         BUG_ON(p == reaper || reaper->exit_state);
598         p->real_parent = reaper;
599 }
600
601 static void reparent_thread(task_t *p, task_t *father, int traced)
602 {
603         /* We don't want people slaying init.  */
604         if (p->exit_signal != -1)
605                 p->exit_signal = SIGCHLD;
606
607         if (p->pdeath_signal)
608                 /* We already hold the tasklist_lock here.  */
609                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
610
611         /* Move the child from its dying parent to the new one.  */
612         if (unlikely(traced)) {
613                 /* Preserve ptrace links if someone else is tracing this child.  */
614                 list_del_init(&p->ptrace_list);
615                 if (p->parent != p->real_parent)
616                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
617         } else {
618                 /* If this child is being traced, then we're the one tracing it
619                  * anyway, so let go of it.
620                  */
621                 p->ptrace = 0;
622                 remove_parent(p);
623                 p->parent = p->real_parent;
624                 add_parent(p);
625
626                 /* If we'd notified the old parent about this child's death,
627                  * also notify the new parent.
628                  */
629                 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
630                     thread_group_empty(p))
631                         do_notify_parent(p, p->exit_signal);
632                 else if (p->state == TASK_TRACED) {
633                         /*
634                          * If it was at a trace stop, turn it into
635                          * a normal stop since it's no longer being
636                          * traced.
637                          */
638                         ptrace_untrace(p);
639                 }
640         }
641
642         /*
643          * process group orphan check
644          * Case ii: Our child is in a different pgrp
645          * than we are, and it was the only connection
646          * outside, so the child pgrp is now orphaned.
647          */
648         if ((process_group(p) != process_group(father)) &&
649             (p->signal->session == father->signal->session)) {
650                 int pgrp = process_group(p);
651
652                 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
653                         __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
654                         __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
655                 }
656         }
657 }
658
659 /*
660  * When we die, we re-parent all our children.
661  * Try to give them to another thread in our thread
662  * group, and if no such member exists, give it to
663  * the global child reaper process (ie "init")
664  */
665 static void forget_original_parent(struct task_struct * father,
666                                           struct list_head *to_release)
667 {
668         struct task_struct *p, *reaper = father;
669         struct list_head *_p, *_n;
670
671         do {
672                 reaper = next_thread(reaper);
673                 if (reaper == father) {
674                         reaper = child_reaper;
675                         break;
676                 }
677         } while (reaper->exit_state);
678
679         /*
680          * There are only two places where our children can be:
681          *
682          * - in our child list
683          * - in our ptraced child list
684          *
685          * Search them and reparent children.
686          */
687         list_for_each_safe(_p, _n, &father->children) {
688                 int ptrace;
689                 p = list_entry(_p,struct task_struct,sibling);
690
691                 ptrace = p->ptrace;
692
693                 /* if father isn't the real parent, then ptrace must be enabled */
694                 BUG_ON(father != p->real_parent && !ptrace);
695
696                 if (father == p->real_parent) {
697                         /* reparent with a reaper, real father it's us */
698                         choose_new_parent(p, reaper);
699                         reparent_thread(p, father, 0);
700                 } else {
701                         /* reparent ptraced task to its real parent */
702                         __ptrace_unlink (p);
703                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
704                             thread_group_empty(p))
705                                 do_notify_parent(p, p->exit_signal);
706                 }
707
708                 /*
709                  * if the ptraced child is a zombie with exit_signal == -1
710                  * we must collect it before we exit, or it will remain
711                  * zombie forever since we prevented it from self-reap itself
712                  * while it was being traced by us, to be able to see it in wait4.
713                  */
714                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
715                         list_add(&p->ptrace_list, to_release);
716         }
717         list_for_each_safe(_p, _n, &father->ptrace_children) {
718                 p = list_entry(_p,struct task_struct,ptrace_list);
719                 choose_new_parent(p, reaper);
720                 reparent_thread(p, father, 1);
721         }
722 }
723
724 /*
725  * Send signals to all our closest relatives so that they know
726  * to properly mourn us..
727  */
728 static void exit_notify(struct task_struct *tsk)
729 {
730         int state;
731         struct task_struct *t;
732         struct list_head ptrace_dead, *_p, *_n;
733
734         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
735             && !thread_group_empty(tsk)) {
736                 /*
737                  * This occurs when there was a race between our exit
738                  * syscall and a group signal choosing us as the one to
739                  * wake up.  It could be that we are the only thread
740                  * alerted to check for pending signals, but another thread
741                  * should be woken now to take the signal since we will not.
742                  * Now we'll wake all the threads in the group just to make
743                  * sure someone gets all the pending signals.
744                  */
745                 read_lock(&tasklist_lock);
746                 spin_lock_irq(&tsk->sighand->siglock);
747                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
748                         if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
749                                 recalc_sigpending_tsk(t);
750                                 if (signal_pending(t))
751                                         signal_wake_up(t, 0);
752                         }
753                 spin_unlock_irq(&tsk->sighand->siglock);
754                 read_unlock(&tasklist_lock);
755         }
756
757         write_lock_irq(&tasklist_lock);
758
759         /*
760          * This does two things:
761          *
762          * A.  Make init inherit all the child processes
763          * B.  Check to see if any process groups have become orphaned
764          *      as a result of our exiting, and if they have any stopped
765          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
766          */
767
768         INIT_LIST_HEAD(&ptrace_dead);
769         forget_original_parent(tsk, &ptrace_dead);
770         BUG_ON(!list_empty(&tsk->children));
771         BUG_ON(!list_empty(&tsk->ptrace_children));
772
773         /*
774          * Check to see if any process groups have become orphaned
775          * as a result of our exiting, and if they have any stopped
776          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
777          *
778          * Case i: Our father is in a different pgrp than we are
779          * and we were the only connection outside, so our pgrp
780          * is about to become orphaned.
781          */
782          
783         t = tsk->real_parent;
784         
785         if ((process_group(t) != process_group(tsk)) &&
786             (t->signal->session == tsk->signal->session) &&
787             will_become_orphaned_pgrp(process_group(tsk), tsk) &&
788             has_stopped_jobs(process_group(tsk))) {
789                 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
790                 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
791         }
792
793         /* Let father know we died 
794          *
795          * Thread signals are configurable, but you aren't going to use
796          * that to send signals to arbitary processes. 
797          * That stops right now.
798          *
799          * If the parent exec id doesn't match the exec id we saved
800          * when we started then we know the parent has changed security
801          * domain.
802          *
803          * If our self_exec id doesn't match our parent_exec_id then
804          * we have changed execution domain as these two values started
805          * the same after a fork.
806          *      
807          */
808         
809         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
810             ( tsk->parent_exec_id != t->self_exec_id  ||
811               tsk->self_exec_id != tsk->parent_exec_id)
812             && !capable(CAP_KILL))
813                 tsk->exit_signal = SIGCHLD;
814
815
816         /* If something other than our normal parent is ptracing us, then
817          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
818          * only has special meaning to our real parent.
819          */
820         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
821                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
822                 do_notify_parent(tsk, signal);
823         } else if (tsk->ptrace) {
824                 do_notify_parent(tsk, SIGCHLD);
825         }
826
827         state = EXIT_ZOMBIE;
828         if (tsk->exit_signal == -1 &&
829             (likely(tsk->ptrace == 0) ||
830              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
831                 state = EXIT_DEAD;
832         tsk->exit_state = state;
833
834         write_unlock_irq(&tasklist_lock);
835
836         list_for_each_safe(_p, _n, &ptrace_dead) {
837                 list_del_init(_p);
838                 t = list_entry(_p,struct task_struct,ptrace_list);
839                 release_task(t);
840         }
841
842         /* If the process is dead, release it - nobody will wait for it */
843         if (state == EXIT_DEAD)
844                 release_task(tsk);
845 }
846
847 fastcall NORET_TYPE void do_exit(long code)
848 {
849         struct task_struct *tsk = current;
850         int group_dead;
851
852         profile_task_exit(tsk);
853
854         WARN_ON(atomic_read(&tsk->fs_excl));
855
856         if (unlikely(in_interrupt()))
857                 panic("Aiee, killing interrupt handler!");
858         if (unlikely(!tsk->pid))
859                 panic("Attempted to kill the idle task!");
860         if (unlikely(tsk == child_reaper))
861                 panic("Attempted to kill init!");
862
863         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
864                 current->ptrace_message = code;
865                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
866         }
867
868         /*
869          * We're taking recursive faults here in do_exit. Safest is to just
870          * leave this task alone and wait for reboot.
871          */
872         if (unlikely(tsk->flags & PF_EXITING)) {
873                 printk(KERN_ALERT
874                         "Fixing recursive fault but reboot is needed!\n");
875                 if (tsk->io_context)
876                         exit_io_context();
877                 set_current_state(TASK_UNINTERRUPTIBLE);
878                 schedule();
879         }
880
881         tsk->flags |= PF_EXITING;
882
883         if (unlikely(in_atomic()))
884                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
885                                 current->comm, current->pid,
886                                 preempt_count());
887
888         acct_update_integrals(tsk);
889         if (tsk->mm) {
890                 update_hiwater_rss(tsk->mm);
891                 update_hiwater_vm(tsk->mm);
892         }
893         group_dead = atomic_dec_and_test(&tsk->signal->live);
894         if (group_dead) {
895                 hrtimer_cancel(&tsk->signal->real_timer);
896                 exit_itimers(tsk->signal);
897                 acct_process(code);
898         }
899         if (unlikely(tsk->robust_list))
900                 exit_robust_list(tsk);
901 #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
902         if (unlikely(tsk->compat_robust_list))
903                 compat_exit_robust_list(tsk);
904 #endif
905         if (unlikely(tsk->audit_context))
906                 audit_free(tsk);
907         exit_mm(tsk);
908
909         exit_sem(tsk);
910         __exit_files(tsk);
911         __exit_fs(tsk);
912         exit_namespace(tsk);
913         exit_thread();
914         cpuset_exit(tsk);
915         exit_keys(tsk);
916
917         if (group_dead && tsk->signal->leader)
918                 disassociate_ctty(1);
919
920         module_put(task_thread_info(tsk)->exec_domain->module);
921         if (tsk->binfmt)
922                 module_put(tsk->binfmt->module);
923
924         tsk->exit_code = code;
925         proc_exit_connector(tsk);
926         exit_notify(tsk);
927 #ifdef CONFIG_NUMA
928         mpol_free(tsk->mempolicy);
929         tsk->mempolicy = NULL;
930 #endif
931         /*
932          * If DEBUG_MUTEXES is on, make sure we are holding no locks:
933          */
934         mutex_debug_check_no_locks_held(tsk);
935
936         if (tsk->io_context)
937                 exit_io_context();
938
939         if (tsk->splice_pipe)
940                 __free_pipe_info(tsk->splice_pipe);
941
942         /* PF_DEAD causes final put_task_struct after we schedule. */
943         preempt_disable();
944         BUG_ON(tsk->flags & PF_DEAD);
945         tsk->flags |= PF_DEAD;
946
947         schedule();
948         BUG();
949         /* Avoid "noreturn function does return".  */
950         for (;;) ;
951 }
952
953 EXPORT_SYMBOL_GPL(do_exit);
954
955 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
956 {
957         if (comp)
958                 complete(comp);
959         
960         do_exit(code);
961 }
962
963 EXPORT_SYMBOL(complete_and_exit);
964
965 asmlinkage long sys_exit(int error_code)
966 {
967         do_exit((error_code&0xff)<<8);
968 }
969
970 /*
971  * Take down every thread in the group.  This is called by fatal signals
972  * as well as by sys_exit_group (below).
973  */
974 NORET_TYPE void
975 do_group_exit(int exit_code)
976 {
977         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
978
979         if (current->signal->flags & SIGNAL_GROUP_EXIT)
980                 exit_code = current->signal->group_exit_code;
981         else if (!thread_group_empty(current)) {
982                 struct signal_struct *const sig = current->signal;
983                 struct sighand_struct *const sighand = current->sighand;
984                 spin_lock_irq(&sighand->siglock);
985                 if (sig->flags & SIGNAL_GROUP_EXIT)
986                         /* Another thread got here before we took the lock.  */
987                         exit_code = sig->group_exit_code;
988                 else {
989                         sig->group_exit_code = exit_code;
990                         zap_other_threads(current);
991                 }
992                 spin_unlock_irq(&sighand->siglock);
993         }
994
995         do_exit(exit_code);
996         /* NOTREACHED */
997 }
998
999 /*
1000  * this kills every thread in the thread group. Note that any externally
1001  * wait4()-ing process will get the correct exit code - even if this
1002  * thread is not the thread group leader.
1003  */
1004 asmlinkage void sys_exit_group(int error_code)
1005 {
1006         do_group_exit((error_code & 0xff) << 8);
1007 }
1008
1009 static int eligible_child(pid_t pid, int options, task_t *p)
1010 {
1011         if (pid > 0) {
1012                 if (p->pid != pid)
1013                         return 0;
1014         } else if (!pid) {
1015                 if (process_group(p) != process_group(current))
1016                         return 0;
1017         } else if (pid != -1) {
1018                 if (process_group(p) != -pid)
1019                         return 0;
1020         }
1021
1022         /*
1023          * Do not consider detached threads that are
1024          * not ptraced:
1025          */
1026         if (p->exit_signal == -1 && !p->ptrace)
1027                 return 0;
1028
1029         /* Wait for all children (clone and not) if __WALL is set;
1030          * otherwise, wait for clone children *only* if __WCLONE is
1031          * set; otherwise, wait for non-clone children *only*.  (Note:
1032          * A "clone" child here is one that reports to its parent
1033          * using a signal other than SIGCHLD.) */
1034         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1035             && !(options & __WALL))
1036                 return 0;
1037         /*
1038          * Do not consider thread group leaders that are
1039          * in a non-empty thread group:
1040          */
1041         if (current->tgid != p->tgid && delay_group_leader(p))
1042                 return 2;
1043
1044         if (security_task_wait(p))
1045                 return 0;
1046
1047         return 1;
1048 }
1049
1050 static int wait_noreap_copyout(task_t *p, pid_t pid, uid_t uid,
1051                                int why, int status,
1052                                struct siginfo __user *infop,
1053                                struct rusage __user *rusagep)
1054 {
1055         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1056         put_task_struct(p);
1057         if (!retval)
1058                 retval = put_user(SIGCHLD, &infop->si_signo);
1059         if (!retval)
1060                 retval = put_user(0, &infop->si_errno);
1061         if (!retval)
1062                 retval = put_user((short)why, &infop->si_code);
1063         if (!retval)
1064                 retval = put_user(pid, &infop->si_pid);
1065         if (!retval)
1066                 retval = put_user(uid, &infop->si_uid);
1067         if (!retval)
1068                 retval = put_user(status, &infop->si_status);
1069         if (!retval)
1070                 retval = pid;
1071         return retval;
1072 }
1073
1074 /*
1075  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1076  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1077  * the lock and this task is uninteresting.  If we return nonzero, we have
1078  * released the lock and the system call should return.
1079  */
1080 static int wait_task_zombie(task_t *p, int noreap,
1081                             struct siginfo __user *infop,
1082                             int __user *stat_addr, struct rusage __user *ru)
1083 {
1084         unsigned long state;
1085         int retval;
1086         int status;
1087
1088         if (unlikely(noreap)) {
1089                 pid_t pid = p->pid;
1090                 uid_t uid = p->uid;
1091                 int exit_code = p->exit_code;
1092                 int why, status;
1093
1094                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1095                         return 0;
1096                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1097                         return 0;
1098                 get_task_struct(p);
1099                 read_unlock(&tasklist_lock);
1100                 if ((exit_code & 0x7f) == 0) {
1101                         why = CLD_EXITED;
1102                         status = exit_code >> 8;
1103                 } else {
1104                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1105                         status = exit_code & 0x7f;
1106                 }
1107                 return wait_noreap_copyout(p, pid, uid, why,
1108                                            status, infop, ru);
1109         }
1110
1111         /*
1112          * Try to move the task's state to DEAD
1113          * only one thread is allowed to do this:
1114          */
1115         state = xchg(&p->exit_state, EXIT_DEAD);
1116         if (state != EXIT_ZOMBIE) {
1117                 BUG_ON(state != EXIT_DEAD);
1118                 return 0;
1119         }
1120         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1121                 /*
1122                  * This can only happen in a race with a ptraced thread
1123                  * dying on another processor.
1124                  */
1125                 return 0;
1126         }
1127
1128         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1129                 struct signal_struct *psig;
1130                 struct signal_struct *sig;
1131
1132                 /*
1133                  * The resource counters for the group leader are in its
1134                  * own task_struct.  Those for dead threads in the group
1135                  * are in its signal_struct, as are those for the child
1136                  * processes it has previously reaped.  All these
1137                  * accumulate in the parent's signal_struct c* fields.
1138                  *
1139                  * We don't bother to take a lock here to protect these
1140                  * p->signal fields, because they are only touched by
1141                  * __exit_signal, which runs with tasklist_lock
1142                  * write-locked anyway, and so is excluded here.  We do
1143                  * need to protect the access to p->parent->signal fields,
1144                  * as other threads in the parent group can be right
1145                  * here reaping other children at the same time.
1146                  */
1147                 spin_lock_irq(&p->parent->sighand->siglock);
1148                 psig = p->parent->signal;
1149                 sig = p->signal;
1150                 psig->cutime =
1151                         cputime_add(psig->cutime,
1152                         cputime_add(p->utime,
1153                         cputime_add(sig->utime,
1154                                     sig->cutime)));
1155                 psig->cstime =
1156                         cputime_add(psig->cstime,
1157                         cputime_add(p->stime,
1158                         cputime_add(sig->stime,
1159                                     sig->cstime)));
1160                 psig->cmin_flt +=
1161                         p->min_flt + sig->min_flt + sig->cmin_flt;
1162                 psig->cmaj_flt +=
1163                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1164                 psig->cnvcsw +=
1165                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1166                 psig->cnivcsw +=
1167                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1168                 spin_unlock_irq(&p->parent->sighand->siglock);
1169         }
1170
1171         /*
1172          * Now we are sure this task is interesting, and no other
1173          * thread can reap it because we set its state to EXIT_DEAD.
1174          */
1175         read_unlock(&tasklist_lock);
1176
1177         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1178         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1179                 ? p->signal->group_exit_code : p->exit_code;
1180         if (!retval && stat_addr)
1181                 retval = put_user(status, stat_addr);
1182         if (!retval && infop)
1183                 retval = put_user(SIGCHLD, &infop->si_signo);
1184         if (!retval && infop)
1185                 retval = put_user(0, &infop->si_errno);
1186         if (!retval && infop) {
1187                 int why;
1188
1189                 if ((status & 0x7f) == 0) {
1190                         why = CLD_EXITED;
1191                         status >>= 8;
1192                 } else {
1193                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1194                         status &= 0x7f;
1195                 }
1196                 retval = put_user((short)why, &infop->si_code);
1197                 if (!retval)
1198                         retval = put_user(status, &infop->si_status);
1199         }
1200         if (!retval && infop)
1201                 retval = put_user(p->pid, &infop->si_pid);
1202         if (!retval && infop)
1203                 retval = put_user(p->uid, &infop->si_uid);
1204         if (retval) {
1205                 // TODO: is this safe?
1206                 p->exit_state = EXIT_ZOMBIE;
1207                 return retval;
1208         }
1209         retval = p->pid;
1210         if (p->real_parent != p->parent) {
1211                 write_lock_irq(&tasklist_lock);
1212                 /* Double-check with lock held.  */
1213                 if (p->real_parent != p->parent) {
1214                         __ptrace_unlink(p);
1215                         // TODO: is this safe?
1216                         p->exit_state = EXIT_ZOMBIE;
1217                         /*
1218                          * If this is not a detached task, notify the parent.
1219                          * If it's still not detached after that, don't release
1220                          * it now.
1221                          */
1222                         if (p->exit_signal != -1) {
1223                                 do_notify_parent(p, p->exit_signal);
1224                                 if (p->exit_signal != -1)
1225                                         p = NULL;
1226                         }
1227                 }
1228                 write_unlock_irq(&tasklist_lock);
1229         }
1230         if (p != NULL)
1231                 release_task(p);
1232         BUG_ON(!retval);
1233         return retval;
1234 }
1235
1236 /*
1237  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1238  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1239  * the lock and this task is uninteresting.  If we return nonzero, we have
1240  * released the lock and the system call should return.
1241  */
1242 static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap,
1243                              struct siginfo __user *infop,
1244                              int __user *stat_addr, struct rusage __user *ru)
1245 {
1246         int retval, exit_code;
1247
1248         if (!p->exit_code)
1249                 return 0;
1250         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1251             p->signal && p->signal->group_stop_count > 0)
1252                 /*
1253                  * A group stop is in progress and this is the group leader.
1254                  * We won't report until all threads have stopped.
1255                  */
1256                 return 0;
1257
1258         /*
1259          * Now we are pretty sure this task is interesting.
1260          * Make sure it doesn't get reaped out from under us while we
1261          * give up the lock and then examine it below.  We don't want to
1262          * keep holding onto the tasklist_lock while we call getrusage and
1263          * possibly take page faults for user memory.
1264          */
1265         get_task_struct(p);
1266         read_unlock(&tasklist_lock);
1267
1268         if (unlikely(noreap)) {
1269                 pid_t pid = p->pid;
1270                 uid_t uid = p->uid;
1271                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1272
1273                 exit_code = p->exit_code;
1274                 if (unlikely(!exit_code) ||
1275                     unlikely(p->state & TASK_TRACED))
1276                         goto bail_ref;
1277                 return wait_noreap_copyout(p, pid, uid,
1278                                            why, (exit_code << 8) | 0x7f,
1279                                            infop, ru);
1280         }
1281
1282         write_lock_irq(&tasklist_lock);
1283
1284         /*
1285          * This uses xchg to be atomic with the thread resuming and setting
1286          * it.  It must also be done with the write lock held to prevent a
1287          * race with the EXIT_ZOMBIE case.
1288          */
1289         exit_code = xchg(&p->exit_code, 0);
1290         if (unlikely(p->exit_state)) {
1291                 /*
1292                  * The task resumed and then died.  Let the next iteration
1293                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1294                  * already be zero here if it resumed and did _exit(0).
1295                  * The task itself is dead and won't touch exit_code again;
1296                  * other processors in this function are locked out.
1297                  */
1298                 p->exit_code = exit_code;
1299                 exit_code = 0;
1300         }
1301         if (unlikely(exit_code == 0)) {
1302                 /*
1303                  * Another thread in this function got to it first, or it
1304                  * resumed, or it resumed and then died.
1305                  */
1306                 write_unlock_irq(&tasklist_lock);
1307 bail_ref:
1308                 put_task_struct(p);
1309                 /*
1310                  * We are returning to the wait loop without having successfully
1311                  * removed the process and having released the lock. We cannot
1312                  * continue, since the "p" task pointer is potentially stale.
1313                  *
1314                  * Return -EAGAIN, and do_wait() will restart the loop from the
1315                  * beginning. Do _not_ re-acquire the lock.
1316                  */
1317                 return -EAGAIN;
1318         }
1319
1320         /* move to end of parent's list to avoid starvation */
1321         remove_parent(p);
1322         add_parent(p);
1323
1324         write_unlock_irq(&tasklist_lock);
1325
1326         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1327         if (!retval && stat_addr)
1328                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1329         if (!retval && infop)
1330                 retval = put_user(SIGCHLD, &infop->si_signo);
1331         if (!retval && infop)
1332                 retval = put_user(0, &infop->si_errno);
1333         if (!retval && infop)
1334                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1335                                           ? CLD_TRAPPED : CLD_STOPPED),
1336                                   &infop->si_code);
1337         if (!retval && infop)
1338                 retval = put_user(exit_code, &infop->si_status);
1339         if (!retval && infop)
1340                 retval = put_user(p->pid, &infop->si_pid);
1341         if (!retval && infop)
1342                 retval = put_user(p->uid, &infop->si_uid);
1343         if (!retval)
1344                 retval = p->pid;
1345         put_task_struct(p);
1346
1347         BUG_ON(!retval);
1348         return retval;
1349 }
1350
1351 /*
1352  * Handle do_wait work for one task in a live, non-stopped state.
1353  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1354  * the lock and this task is uninteresting.  If we return nonzero, we have
1355  * released the lock and the system call should return.
1356  */
1357 static int wait_task_continued(task_t *p, int noreap,
1358                                struct siginfo __user *infop,
1359                                int __user *stat_addr, struct rusage __user *ru)
1360 {
1361         int retval;
1362         pid_t pid;
1363         uid_t uid;
1364
1365         if (unlikely(!p->signal))
1366                 return 0;
1367
1368         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1369                 return 0;
1370
1371         spin_lock_irq(&p->sighand->siglock);
1372         /* Re-check with the lock held.  */
1373         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1374                 spin_unlock_irq(&p->sighand->siglock);
1375                 return 0;
1376         }
1377         if (!noreap)
1378                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1379         spin_unlock_irq(&p->sighand->siglock);
1380
1381         pid = p->pid;
1382         uid = p->uid;
1383         get_task_struct(p);
1384         read_unlock(&tasklist_lock);
1385
1386         if (!infop) {
1387                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1388                 put_task_struct(p);
1389                 if (!retval && stat_addr)
1390                         retval = put_user(0xffff, stat_addr);
1391                 if (!retval)
1392                         retval = p->pid;
1393         } else {
1394                 retval = wait_noreap_copyout(p, pid, uid,
1395                                              CLD_CONTINUED, SIGCONT,
1396                                              infop, ru);
1397                 BUG_ON(retval == 0);
1398         }
1399
1400         return retval;
1401 }
1402
1403
1404 static inline int my_ptrace_child(struct task_struct *p)
1405 {
1406         if (!(p->ptrace & PT_PTRACED))
1407                 return 0;
1408         if (!(p->ptrace & PT_ATTACHED))
1409                 return 1;
1410         /*
1411          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1412          * we are the attacher.  If we are the real parent, this is a race
1413          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1414          * which we have to switch the parent links, but has already set
1415          * the flags in p->ptrace.
1416          */
1417         return (p->parent != p->real_parent);
1418 }
1419
1420 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1421                     int __user *stat_addr, struct rusage __user *ru)
1422 {
1423         DECLARE_WAITQUEUE(wait, current);
1424         struct task_struct *tsk;
1425         int flag, retval;
1426
1427         add_wait_queue(&current->signal->wait_chldexit,&wait);
1428 repeat:
1429         /*
1430          * We will set this flag if we see any child that might later
1431          * match our criteria, even if we are not able to reap it yet.
1432          */
1433         flag = 0;
1434         current->state = TASK_INTERRUPTIBLE;
1435         read_lock(&tasklist_lock);
1436         tsk = current;
1437         do {
1438                 struct task_struct *p;
1439                 struct list_head *_p;
1440                 int ret;
1441
1442                 list_for_each(_p,&tsk->children) {
1443                         p = list_entry(_p,struct task_struct,sibling);
1444
1445                         ret = eligible_child(pid, options, p);
1446                         if (!ret)
1447                                 continue;
1448
1449                         switch (p->state) {
1450                         case TASK_TRACED:
1451                                 /*
1452                                  * When we hit the race with PTRACE_ATTACH,
1453                                  * we will not report this child.  But the
1454                                  * race means it has not yet been moved to
1455                                  * our ptrace_children list, so we need to
1456                                  * set the flag here to avoid a spurious ECHILD
1457                                  * when the race happens with the only child.
1458                                  */
1459                                 flag = 1;
1460                                 if (!my_ptrace_child(p))
1461                                         continue;
1462                                 /*FALLTHROUGH*/
1463                         case TASK_STOPPED:
1464                                 /*
1465                                  * It's stopped now, so it might later
1466                                  * continue, exit, or stop again.
1467                                  */
1468                                 flag = 1;
1469                                 if (!(options & WUNTRACED) &&
1470                                     !my_ptrace_child(p))
1471                                         continue;
1472                                 retval = wait_task_stopped(p, ret == 2,
1473                                                            (options & WNOWAIT),
1474                                                            infop,
1475                                                            stat_addr, ru);
1476                                 if (retval == -EAGAIN)
1477                                         goto repeat;
1478                                 if (retval != 0) /* He released the lock.  */
1479                                         goto end;
1480                                 break;
1481                         default:
1482                         // case EXIT_DEAD:
1483                                 if (p->exit_state == EXIT_DEAD)
1484                                         continue;
1485                         // case EXIT_ZOMBIE:
1486                                 if (p->exit_state == EXIT_ZOMBIE) {
1487                                         /*
1488                                          * Eligible but we cannot release
1489                                          * it yet:
1490                                          */
1491                                         if (ret == 2)
1492                                                 goto check_continued;
1493                                         if (!likely(options & WEXITED))
1494                                                 continue;
1495                                         retval = wait_task_zombie(
1496                                                 p, (options & WNOWAIT),
1497                                                 infop, stat_addr, ru);
1498                                         /* He released the lock.  */
1499                                         if (retval != 0)
1500                                                 goto end;
1501                                         break;
1502                                 }
1503 check_continued:
1504                                 /*
1505                                  * It's running now, so it might later
1506                                  * exit, stop, or stop and then continue.
1507                                  */
1508                                 flag = 1;
1509                                 if (!unlikely(options & WCONTINUED))
1510                                         continue;
1511                                 retval = wait_task_continued(
1512                                         p, (options & WNOWAIT),
1513                                         infop, stat_addr, ru);
1514                                 if (retval != 0) /* He released the lock.  */
1515                                         goto end;
1516                                 break;
1517                         }
1518                 }
1519                 if (!flag) {
1520                         list_for_each(_p, &tsk->ptrace_children) {
1521                                 p = list_entry(_p, struct task_struct,
1522                                                 ptrace_list);
1523                                 if (!eligible_child(pid, options, p))
1524                                         continue;
1525                                 flag = 1;
1526                                 break;
1527                         }
1528                 }
1529                 if (options & __WNOTHREAD)
1530                         break;
1531                 tsk = next_thread(tsk);
1532                 BUG_ON(tsk->signal != current->signal);
1533         } while (tsk != current);
1534
1535         read_unlock(&tasklist_lock);
1536         if (flag) {
1537                 retval = 0;
1538                 if (options & WNOHANG)
1539                         goto end;
1540                 retval = -ERESTARTSYS;
1541                 if (signal_pending(current))
1542                         goto end;
1543                 schedule();
1544                 goto repeat;
1545         }
1546         retval = -ECHILD;
1547 end:
1548         current->state = TASK_RUNNING;
1549         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1550         if (infop) {
1551                 if (retval > 0)
1552                 retval = 0;
1553                 else {
1554                         /*
1555                          * For a WNOHANG return, clear out all the fields
1556                          * we would set so the user can easily tell the
1557                          * difference.
1558                          */
1559                         if (!retval)
1560                                 retval = put_user(0, &infop->si_signo);
1561                         if (!retval)
1562                                 retval = put_user(0, &infop->si_errno);
1563                         if (!retval)
1564                                 retval = put_user(0, &infop->si_code);
1565                         if (!retval)
1566                                 retval = put_user(0, &infop->si_pid);
1567                         if (!retval)
1568                                 retval = put_user(0, &infop->si_uid);
1569                         if (!retval)
1570                                 retval = put_user(0, &infop->si_status);
1571                 }
1572         }
1573         return retval;
1574 }
1575
1576 asmlinkage long sys_waitid(int which, pid_t pid,
1577                            struct siginfo __user *infop, int options,
1578                            struct rusage __user *ru)
1579 {
1580         long ret;
1581
1582         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1583                 return -EINVAL;
1584         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1585                 return -EINVAL;
1586
1587         switch (which) {
1588         case P_ALL:
1589                 pid = -1;
1590                 break;
1591         case P_PID:
1592                 if (pid <= 0)
1593                         return -EINVAL;
1594                 break;
1595         case P_PGID:
1596                 if (pid <= 0)
1597                         return -EINVAL;
1598                 pid = -pid;
1599                 break;
1600         default:
1601                 return -EINVAL;
1602         }
1603
1604         ret = do_wait(pid, options, infop, NULL, ru);
1605
1606         /* avoid REGPARM breakage on x86: */
1607         prevent_tail_call(ret);
1608         return ret;
1609 }
1610
1611 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1612                           int options, struct rusage __user *ru)
1613 {
1614         long ret;
1615
1616         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1617                         __WNOTHREAD|__WCLONE|__WALL))
1618                 return -EINVAL;
1619         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1620
1621         /* avoid REGPARM breakage on x86: */
1622         prevent_tail_call(ret);
1623         return ret;
1624 }
1625
1626 #ifdef __ARCH_WANT_SYS_WAITPID
1627
1628 /*
1629  * sys_waitpid() remains for compatibility. waitpid() should be
1630  * implemented by calling sys_wait4() from libc.a.
1631  */
1632 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1633 {
1634         return sys_wait4(pid, stat_addr, options, NULL);
1635 }
1636
1637 #endif