67c1e9a4f812a039ce7def1fd1599b74841150f7
[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/mm.h>
8 #include <linux/slab.h>
9 #include <linux/interrupt.h>
10 #include <linux/smp_lock.h>
11 #include <linux/module.h>
12 #include <linux/capability.h>
13 #include <linux/completion.h>
14 #include <linux/personality.h>
15 #include <linux/tty.h>
16 #include <linux/namespace.h>
17 #include <linux/key.h>
18 #include <linux/security.h>
19 #include <linux/cpu.h>
20 #include <linux/acct.h>
21 #include <linux/file.h>
22 #include <linux/binfmts.h>
23 #include <linux/ptrace.h>
24 #include <linux/profile.h>
25 #include <linux/mount.h>
26 #include <linux/proc_fs.h>
27 #include <linux/mempolicy.h>
28 #include <linux/taskstats_kern.h>
29 #include <linux/delayacct.h>
30 #include <linux/cpuset.h>
31 #include <linux/syscalls.h>
32 #include <linux/signal.h>
33 #include <linux/posix-timers.h>
34 #include <linux/cn_proc.h>
35 #include <linux/mutex.h>
36 #include <linux/futex.h>
37 #include <linux/compat.h>
38 #include <linux/pipe_fs_i.h>
39 #include <linux/audit.h> /* for audit_free() */
40 #include <linux/resource.h>
41
42 #include <asm/uaccess.h>
43 #include <asm/unistd.h>
44 #include <asm/pgtable.h>
45 #include <asm/mmu_context.h>
46
47 extern void sem_exit (void);
48 extern struct task_struct *child_reaper;
49
50 static void exit_mm(struct task_struct * tsk);
51
52 static void __unhash_process(struct task_struct *p)
53 {
54         nr_threads--;
55         detach_pid(p, PIDTYPE_PID);
56         if (thread_group_leader(p)) {
57                 detach_pid(p, PIDTYPE_PGID);
58                 detach_pid(p, PIDTYPE_SID);
59
60                 list_del_rcu(&p->tasks);
61                 __get_cpu_var(process_counts)--;
62         }
63         list_del_rcu(&p->thread_group);
64         remove_parent(p);
65 }
66
67 /*
68  * This function expects the tasklist_lock write-locked.
69  */
70 static void __exit_signal(struct task_struct *tsk)
71 {
72         struct signal_struct *sig = tsk->signal;
73         struct sighand_struct *sighand;
74
75         BUG_ON(!sig);
76         BUG_ON(!atomic_read(&sig->count));
77
78         rcu_read_lock();
79         sighand = rcu_dereference(tsk->sighand);
80         spin_lock(&sighand->siglock);
81
82         posix_cpu_timers_exit(tsk);
83         if (atomic_dec_and_test(&sig->count))
84                 posix_cpu_timers_exit_group(tsk);
85         else {
86                 /*
87                  * If there is any task waiting for the group exit
88                  * then notify it:
89                  */
90                 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
91                         wake_up_process(sig->group_exit_task);
92                         sig->group_exit_task = NULL;
93                 }
94                 if (tsk == sig->curr_target)
95                         sig->curr_target = next_thread(tsk);
96                 /*
97                  * Accumulate here the counters for all threads but the
98                  * group leader as they die, so they can be added into
99                  * the process-wide totals when those are taken.
100                  * The group leader stays around as a zombie as long
101                  * as there are other threads.  When it gets reaped,
102                  * the exit.c code will add its counts into these totals.
103                  * We won't ever get here for the group leader, since it
104                  * will have been the last reference on the signal_struct.
105                  */
106                 sig->utime = cputime_add(sig->utime, tsk->utime);
107                 sig->stime = cputime_add(sig->stime, tsk->stime);
108                 sig->min_flt += tsk->min_flt;
109                 sig->maj_flt += tsk->maj_flt;
110                 sig->nvcsw += tsk->nvcsw;
111                 sig->nivcsw += tsk->nivcsw;
112                 sig->sched_time += tsk->sched_time;
113                 sig = NULL; /* Marker for below. */
114         }
115
116         __unhash_process(tsk);
117
118         tsk->signal = NULL;
119         tsk->sighand = NULL;
120         spin_unlock(&sighand->siglock);
121         rcu_read_unlock();
122
123         __cleanup_sighand(sighand);
124         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
125         flush_sigqueue(&tsk->pending);
126         if (sig) {
127                 flush_sigqueue(&sig->shared_pending);
128                 __cleanup_signal(sig);
129         }
130 }
131
132 static void delayed_put_task_struct(struct rcu_head *rhp)
133 {
134         put_task_struct(container_of(rhp, struct task_struct, rcu));
135 }
136
137 void release_task(struct task_struct * p)
138 {
139         struct task_struct *leader;
140         int zap_leader;
141 repeat:
142         atomic_dec(&p->user->processes);
143         write_lock_irq(&tasklist_lock);
144         ptrace_unlink(p);
145         BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
146         __exit_signal(p);
147
148         /*
149          * If we are the last non-leader member of the thread
150          * group, and the leader is zombie, then notify the
151          * group leader's parent process. (if it wants notification.)
152          */
153         zap_leader = 0;
154         leader = p->group_leader;
155         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
156                 BUG_ON(leader->exit_signal == -1);
157                 do_notify_parent(leader, leader->exit_signal);
158                 /*
159                  * If we were the last child thread and the leader has
160                  * exited already, and the leader's parent ignores SIGCHLD,
161                  * then we are the one who should release the leader.
162                  *
163                  * do_notify_parent() will have marked it self-reaping in
164                  * that case.
165                  */
166                 zap_leader = (leader->exit_signal == -1);
167         }
168
169         sched_exit(p);
170         write_unlock_irq(&tasklist_lock);
171         proc_flush_task(p);
172         release_thread(p);
173         call_rcu(&p->rcu, delayed_put_task_struct);
174
175         p = leader;
176         if (unlikely(zap_leader))
177                 goto repeat;
178 }
179
180 /*
181  * This checks not only the pgrp, but falls back on the pid if no
182  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
183  * without this...
184  */
185 int session_of_pgrp(int pgrp)
186 {
187         struct task_struct *p;
188         int sid = -1;
189
190         read_lock(&tasklist_lock);
191         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
192                 if (p->signal->session > 0) {
193                         sid = p->signal->session;
194                         goto out;
195                 }
196         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
197         p = find_task_by_pid(pgrp);
198         if (p)
199                 sid = p->signal->session;
200 out:
201         read_unlock(&tasklist_lock);
202         
203         return sid;
204 }
205
206 /*
207  * Determine if a process group is "orphaned", according to the POSIX
208  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
209  * by terminal-generated stop signals.  Newly orphaned process groups are
210  * to receive a SIGHUP and a SIGCONT.
211  *
212  * "I ask you, have you ever known what it is to be an orphan?"
213  */
214 static int will_become_orphaned_pgrp(int pgrp, struct task_struct *ignored_task)
215 {
216         struct task_struct *p;
217         int ret = 1;
218
219         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
220                 if (p == ignored_task
221                                 || p->exit_state
222                                 || p->real_parent->pid == 1)
223                         continue;
224                 if (process_group(p->real_parent) != pgrp
225                             && p->real_parent->signal->session == p->signal->session) {
226                         ret = 0;
227                         break;
228                 }
229         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
230         return ret;     /* (sighing) "Often!" */
231 }
232
233 int is_orphaned_pgrp(int pgrp)
234 {
235         int retval;
236
237         read_lock(&tasklist_lock);
238         retval = will_become_orphaned_pgrp(pgrp, NULL);
239         read_unlock(&tasklist_lock);
240
241         return retval;
242 }
243
244 static int has_stopped_jobs(int pgrp)
245 {
246         int retval = 0;
247         struct task_struct *p;
248
249         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
250                 if (p->state != TASK_STOPPED)
251                         continue;
252
253                 /* If p is stopped by a debugger on a signal that won't
254                    stop it, then don't count p as stopped.  This isn't
255                    perfect but it's a good approximation.  */
256                 if (unlikely (p->ptrace)
257                     && p->exit_code != SIGSTOP
258                     && p->exit_code != SIGTSTP
259                     && p->exit_code != SIGTTOU
260                     && p->exit_code != SIGTTIN)
261                         continue;
262
263                 retval = 1;
264                 break;
265         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
266         return retval;
267 }
268
269 /**
270  * reparent_to_init - Reparent the calling kernel thread to the init task.
271  *
272  * If a kernel thread is launched as a result of a system call, or if
273  * it ever exits, it should generally reparent itself to init so that
274  * it is correctly cleaned up on exit.
275  *
276  * The various task state such as scheduling policy and priority may have
277  * been inherited from a user process, so we reset them to sane values here.
278  *
279  * NOTE that reparent_to_init() gives the caller full capabilities.
280  */
281 static void reparent_to_init(void)
282 {
283         write_lock_irq(&tasklist_lock);
284
285         ptrace_unlink(current);
286         /* Reparent to init */
287         remove_parent(current);
288         current->parent = child_reaper;
289         current->real_parent = child_reaper;
290         add_parent(current);
291
292         /* Set the exit signal to SIGCHLD so we signal init on exit */
293         current->exit_signal = SIGCHLD;
294
295         if ((current->policy == SCHED_NORMAL ||
296                         current->policy == SCHED_BATCH)
297                                 && (task_nice(current) < 0))
298                 set_user_nice(current, 0);
299         /* cpus_allowed? */
300         /* rt_priority? */
301         /* signals? */
302         security_task_reparent_to_init(current);
303         memcpy(current->signal->rlim, init_task.signal->rlim,
304                sizeof(current->signal->rlim));
305         atomic_inc(&(INIT_USER->__count));
306         write_unlock_irq(&tasklist_lock);
307         switch_uid(INIT_USER);
308 }
309
310 void __set_special_pids(pid_t session, pid_t pgrp)
311 {
312         struct task_struct *curr = current->group_leader;
313
314         if (curr->signal->session != session) {
315                 detach_pid(curr, PIDTYPE_SID);
316                 curr->signal->session = session;
317                 attach_pid(curr, PIDTYPE_SID, session);
318         }
319         if (process_group(curr) != pgrp) {
320                 detach_pid(curr, PIDTYPE_PGID);
321                 curr->signal->pgrp = pgrp;
322                 attach_pid(curr, PIDTYPE_PGID, pgrp);
323         }
324 }
325
326 void set_special_pids(pid_t session, pid_t pgrp)
327 {
328         write_lock_irq(&tasklist_lock);
329         __set_special_pids(session, pgrp);
330         write_unlock_irq(&tasklist_lock);
331 }
332
333 /*
334  * Let kernel threads use this to say that they
335  * allow a certain signal (since daemonize() will
336  * have disabled all of them by default).
337  */
338 int allow_signal(int sig)
339 {
340         if (!valid_signal(sig) || sig < 1)
341                 return -EINVAL;
342
343         spin_lock_irq(&current->sighand->siglock);
344         sigdelset(&current->blocked, sig);
345         if (!current->mm) {
346                 /* Kernel threads handle their own signals.
347                    Let the signal code know it'll be handled, so
348                    that they don't get converted to SIGKILL or
349                    just silently dropped */
350                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
351         }
352         recalc_sigpending();
353         spin_unlock_irq(&current->sighand->siglock);
354         return 0;
355 }
356
357 EXPORT_SYMBOL(allow_signal);
358
359 int disallow_signal(int sig)
360 {
361         if (!valid_signal(sig) || sig < 1)
362                 return -EINVAL;
363
364         spin_lock_irq(&current->sighand->siglock);
365         sigaddset(&current->blocked, sig);
366         recalc_sigpending();
367         spin_unlock_irq(&current->sighand->siglock);
368         return 0;
369 }
370
371 EXPORT_SYMBOL(disallow_signal);
372
373 /*
374  *      Put all the gunge required to become a kernel thread without
375  *      attached user resources in one place where it belongs.
376  */
377
378 void daemonize(const char *name, ...)
379 {
380         va_list args;
381         struct fs_struct *fs;
382         sigset_t blocked;
383
384         va_start(args, name);
385         vsnprintf(current->comm, sizeof(current->comm), name, args);
386         va_end(args);
387
388         /*
389          * If we were started as result of loading a module, close all of the
390          * user space pages.  We don't need them, and if we didn't close them
391          * they would be locked into memory.
392          */
393         exit_mm(current);
394
395         set_special_pids(1, 1);
396         mutex_lock(&tty_mutex);
397         current->signal->tty = NULL;
398         mutex_unlock(&tty_mutex);
399
400         /* Block and flush all signals */
401         sigfillset(&blocked);
402         sigprocmask(SIG_BLOCK, &blocked, NULL);
403         flush_signals(current);
404
405         /* Become as one with the init task */
406
407         exit_fs(current);       /* current->fs->count--; */
408         fs = init_task.fs;
409         current->fs = fs;
410         atomic_inc(&fs->count);
411         exit_namespace(current);
412         current->namespace = init_task.namespace;
413         get_namespace(current->namespace);
414         exit_files(current);
415         current->files = init_task.files;
416         atomic_inc(&current->files->count);
417
418         reparent_to_init();
419 }
420
421 EXPORT_SYMBOL(daemonize);
422
423 static void close_files(struct files_struct * files)
424 {
425         int i, j;
426         struct fdtable *fdt;
427
428         j = 0;
429
430         /*
431          * It is safe to dereference the fd table without RCU or
432          * ->file_lock because this is the last reference to the
433          * files structure.
434          */
435         fdt = files_fdtable(files);
436         for (;;) {
437                 unsigned long set;
438                 i = j * __NFDBITS;
439                 if (i >= fdt->max_fdset || i >= fdt->max_fds)
440                         break;
441                 set = fdt->open_fds->fds_bits[j++];
442                 while (set) {
443                         if (set & 1) {
444                                 struct file * file = xchg(&fdt->fd[i], NULL);
445                                 if (file)
446                                         filp_close(file, files);
447                         }
448                         i++;
449                         set >>= 1;
450                 }
451         }
452 }
453
454 struct files_struct *get_files_struct(struct task_struct *task)
455 {
456         struct files_struct *files;
457
458         task_lock(task);
459         files = task->files;
460         if (files)
461                 atomic_inc(&files->count);
462         task_unlock(task);
463
464         return files;
465 }
466
467 void fastcall put_files_struct(struct files_struct *files)
468 {
469         struct fdtable *fdt;
470
471         if (atomic_dec_and_test(&files->count)) {
472                 close_files(files);
473                 /*
474                  * Free the fd and fdset arrays if we expanded them.
475                  * If the fdtable was embedded, pass files for freeing
476                  * at the end of the RCU grace period. Otherwise,
477                  * you can free files immediately.
478                  */
479                 fdt = files_fdtable(files);
480                 if (fdt == &files->fdtab)
481                         fdt->free_files = files;
482                 else
483                         kmem_cache_free(files_cachep, files);
484                 free_fdtable(fdt);
485         }
486 }
487
488 EXPORT_SYMBOL(put_files_struct);
489
490 static inline void __exit_files(struct task_struct *tsk)
491 {
492         struct files_struct * files = tsk->files;
493
494         if (files) {
495                 task_lock(tsk);
496                 tsk->files = NULL;
497                 task_unlock(tsk);
498                 put_files_struct(files);
499         }
500 }
501
502 void exit_files(struct task_struct *tsk)
503 {
504         __exit_files(tsk);
505 }
506
507 static inline void __put_fs_struct(struct fs_struct *fs)
508 {
509         /* No need to hold fs->lock if we are killing it */
510         if (atomic_dec_and_test(&fs->count)) {
511                 dput(fs->root);
512                 mntput(fs->rootmnt);
513                 dput(fs->pwd);
514                 mntput(fs->pwdmnt);
515                 if (fs->altroot) {
516                         dput(fs->altroot);
517                         mntput(fs->altrootmnt);
518                 }
519                 kmem_cache_free(fs_cachep, fs);
520         }
521 }
522
523 void put_fs_struct(struct fs_struct *fs)
524 {
525         __put_fs_struct(fs);
526 }
527
528 static inline void __exit_fs(struct task_struct *tsk)
529 {
530         struct fs_struct * fs = tsk->fs;
531
532         if (fs) {
533                 task_lock(tsk);
534                 tsk->fs = NULL;
535                 task_unlock(tsk);
536                 __put_fs_struct(fs);
537         }
538 }
539
540 void exit_fs(struct task_struct *tsk)
541 {
542         __exit_fs(tsk);
543 }
544
545 EXPORT_SYMBOL_GPL(exit_fs);
546
547 /*
548  * Turn us into a lazy TLB process if we
549  * aren't already..
550  */
551 static void exit_mm(struct task_struct * tsk)
552 {
553         struct mm_struct *mm = tsk->mm;
554
555         mm_release(tsk, mm);
556         if (!mm)
557                 return;
558         /*
559          * Serialize with any possible pending coredump.
560          * We must hold mmap_sem around checking core_waiters
561          * and clearing tsk->mm.  The core-inducing thread
562          * will increment core_waiters for each thread in the
563          * group with ->mm != NULL.
564          */
565         down_read(&mm->mmap_sem);
566         if (mm->core_waiters) {
567                 up_read(&mm->mmap_sem);
568                 down_write(&mm->mmap_sem);
569                 if (!--mm->core_waiters)
570                         complete(mm->core_startup_done);
571                 up_write(&mm->mmap_sem);
572
573                 wait_for_completion(&mm->core_done);
574                 down_read(&mm->mmap_sem);
575         }
576         atomic_inc(&mm->mm_count);
577         BUG_ON(mm != tsk->active_mm);
578         /* more a memory barrier than a real lock */
579         task_lock(tsk);
580         tsk->mm = NULL;
581         up_read(&mm->mmap_sem);
582         enter_lazy_tlb(mm, current);
583         task_unlock(tsk);
584         mmput(mm);
585 }
586
587 static inline void
588 choose_new_parent(struct task_struct *p, struct task_struct *reaper)
589 {
590         /*
591          * Make sure we're not reparenting to ourselves and that
592          * the parent is not a zombie.
593          */
594         BUG_ON(p == reaper || reaper->exit_state);
595         p->real_parent = reaper;
596 }
597
598 static void
599 reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
600 {
601         /* We don't want people slaying init.  */
602         if (p->exit_signal != -1)
603                 p->exit_signal = SIGCHLD;
604
605         if (p->pdeath_signal)
606                 /* We already hold the tasklist_lock here.  */
607                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
608
609         /* Move the child from its dying parent to the new one.  */
610         if (unlikely(traced)) {
611                 /* Preserve ptrace links if someone else is tracing this child.  */
612                 list_del_init(&p->ptrace_list);
613                 if (p->parent != p->real_parent)
614                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
615         } else {
616                 /* If this child is being traced, then we're the one tracing it
617                  * anyway, so let go of it.
618                  */
619                 p->ptrace = 0;
620                 remove_parent(p);
621                 p->parent = p->real_parent;
622                 add_parent(p);
623
624                 /* If we'd notified the old parent about this child's death,
625                  * also notify the new parent.
626                  */
627                 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
628                     thread_group_empty(p))
629                         do_notify_parent(p, p->exit_signal);
630                 else if (p->state == TASK_TRACED) {
631                         /*
632                          * If it was at a trace stop, turn it into
633                          * a normal stop since it's no longer being
634                          * traced.
635                          */
636                         ptrace_untrace(p);
637                 }
638         }
639
640         /*
641          * process group orphan check
642          * Case ii: Our child is in a different pgrp
643          * than we are, and it was the only connection
644          * outside, so the child pgrp is now orphaned.
645          */
646         if ((process_group(p) != process_group(father)) &&
647             (p->signal->session == father->signal->session)) {
648                 int pgrp = process_group(p);
649
650                 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
651                         __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
652                         __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
653                 }
654         }
655 }
656
657 /*
658  * When we die, we re-parent all our children.
659  * Try to give them to another thread in our thread
660  * group, and if no such member exists, give it to
661  * the global child reaper process (ie "init")
662  */
663 static void
664 forget_original_parent(struct task_struct *father, struct list_head *to_release)
665 {
666         struct task_struct *p, *reaper = father;
667         struct list_head *_p, *_n;
668
669         do {
670                 reaper = next_thread(reaper);
671                 if (reaper == father) {
672                         reaper = child_reaper;
673                         break;
674                 }
675         } while (reaper->exit_state);
676
677         /*
678          * There are only two places where our children can be:
679          *
680          * - in our child list
681          * - in our ptraced child list
682          *
683          * Search them and reparent children.
684          */
685         list_for_each_safe(_p, _n, &father->children) {
686                 int ptrace;
687                 p = list_entry(_p, struct task_struct, sibling);
688
689                 ptrace = p->ptrace;
690
691                 /* if father isn't the real parent, then ptrace must be enabled */
692                 BUG_ON(father != p->real_parent && !ptrace);
693
694                 if (father == p->real_parent) {
695                         /* reparent with a reaper, real father it's us */
696                         choose_new_parent(p, reaper);
697                         reparent_thread(p, father, 0);
698                 } else {
699                         /* reparent ptraced task to its real parent */
700                         __ptrace_unlink (p);
701                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
702                             thread_group_empty(p))
703                                 do_notify_parent(p, p->exit_signal);
704                 }
705
706                 /*
707                  * if the ptraced child is a zombie with exit_signal == -1
708                  * we must collect it before we exit, or it will remain
709                  * zombie forever since we prevented it from self-reap itself
710                  * while it was being traced by us, to be able to see it in wait4.
711                  */
712                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
713                         list_add(&p->ptrace_list, to_release);
714         }
715         list_for_each_safe(_p, _n, &father->ptrace_children) {
716                 p = list_entry(_p, struct task_struct, ptrace_list);
717                 choose_new_parent(p, reaper);
718                 reparent_thread(p, father, 1);
719         }
720 }
721
722 /*
723  * Send signals to all our closest relatives so that they know
724  * to properly mourn us..
725  */
726 static void exit_notify(struct task_struct *tsk)
727 {
728         int state;
729         struct task_struct *t;
730         struct list_head ptrace_dead, *_p, *_n;
731
732         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
733             && !thread_group_empty(tsk)) {
734                 /*
735                  * This occurs when there was a race between our exit
736                  * syscall and a group signal choosing us as the one to
737                  * wake up.  It could be that we are the only thread
738                  * alerted to check for pending signals, but another thread
739                  * should be woken now to take the signal since we will not.
740                  * Now we'll wake all the threads in the group just to make
741                  * sure someone gets all the pending signals.
742                  */
743                 read_lock(&tasklist_lock);
744                 spin_lock_irq(&tsk->sighand->siglock);
745                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
746                         if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
747                                 recalc_sigpending_tsk(t);
748                                 if (signal_pending(t))
749                                         signal_wake_up(t, 0);
750                         }
751                 spin_unlock_irq(&tsk->sighand->siglock);
752                 read_unlock(&tasklist_lock);
753         }
754
755         write_lock_irq(&tasklist_lock);
756
757         /*
758          * This does two things:
759          *
760          * A.  Make init inherit all the child processes
761          * B.  Check to see if any process groups have become orphaned
762          *      as a result of our exiting, and if they have any stopped
763          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
764          */
765
766         INIT_LIST_HEAD(&ptrace_dead);
767         forget_original_parent(tsk, &ptrace_dead);
768         BUG_ON(!list_empty(&tsk->children));
769         BUG_ON(!list_empty(&tsk->ptrace_children));
770
771         /*
772          * Check to see if any process groups have become orphaned
773          * as a result of our exiting, and if they have any stopped
774          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
775          *
776          * Case i: Our father is in a different pgrp than we are
777          * and we were the only connection outside, so our pgrp
778          * is about to become orphaned.
779          */
780          
781         t = tsk->real_parent;
782         
783         if ((process_group(t) != process_group(tsk)) &&
784             (t->signal->session == tsk->signal->session) &&
785             will_become_orphaned_pgrp(process_group(tsk), tsk) &&
786             has_stopped_jobs(process_group(tsk))) {
787                 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
788                 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
789         }
790
791         /* Let father know we died 
792          *
793          * Thread signals are configurable, but you aren't going to use
794          * that to send signals to arbitary processes. 
795          * That stops right now.
796          *
797          * If the parent exec id doesn't match the exec id we saved
798          * when we started then we know the parent has changed security
799          * domain.
800          *
801          * If our self_exec id doesn't match our parent_exec_id then
802          * we have changed execution domain as these two values started
803          * the same after a fork.
804          *      
805          */
806         
807         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
808             ( tsk->parent_exec_id != t->self_exec_id  ||
809               tsk->self_exec_id != tsk->parent_exec_id)
810             && !capable(CAP_KILL))
811                 tsk->exit_signal = SIGCHLD;
812
813
814         /* If something other than our normal parent is ptracing us, then
815          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
816          * only has special meaning to our real parent.
817          */
818         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
819                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
820                 do_notify_parent(tsk, signal);
821         } else if (tsk->ptrace) {
822                 do_notify_parent(tsk, SIGCHLD);
823         }
824
825         state = EXIT_ZOMBIE;
826         if (tsk->exit_signal == -1 &&
827             (likely(tsk->ptrace == 0) ||
828              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
829                 state = EXIT_DEAD;
830         tsk->exit_state = state;
831
832         write_unlock_irq(&tasklist_lock);
833
834         list_for_each_safe(_p, _n, &ptrace_dead) {
835                 list_del_init(_p);
836                 t = list_entry(_p, struct task_struct, ptrace_list);
837                 release_task(t);
838         }
839
840         /* If the process is dead, release it - nobody will wait for it */
841         if (state == EXIT_DEAD)
842                 release_task(tsk);
843 }
844
845 fastcall NORET_TYPE void do_exit(long code)
846 {
847         struct task_struct *tsk = current;
848         struct taskstats *tidstats;
849         int group_dead;
850
851         profile_task_exit(tsk);
852
853         WARN_ON(atomic_read(&tsk->fs_excl));
854
855         if (unlikely(in_interrupt()))
856                 panic("Aiee, killing interrupt handler!");
857         if (unlikely(!tsk->pid))
858                 panic("Attempted to kill the idle task!");
859         if (unlikely(tsk == child_reaper))
860                 panic("Attempted to kill init!");
861
862         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
863                 current->ptrace_message = code;
864                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
865         }
866
867         /*
868          * We're taking recursive faults here in do_exit. Safest is to just
869          * leave this task alone and wait for reboot.
870          */
871         if (unlikely(tsk->flags & PF_EXITING)) {
872                 printk(KERN_ALERT
873                         "Fixing recursive fault but reboot is needed!\n");
874                 if (tsk->io_context)
875                         exit_io_context();
876                 set_current_state(TASK_UNINTERRUPTIBLE);
877                 schedule();
878         }
879
880         tsk->flags |= PF_EXITING;
881
882         if (unlikely(in_atomic()))
883                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
884                                 current->comm, current->pid,
885                                 preempt_count());
886
887         taskstats_exit_alloc(&tidstats);
888
889         acct_update_integrals(tsk);
890         if (tsk->mm) {
891                 update_hiwater_rss(tsk->mm);
892                 update_hiwater_vm(tsk->mm);
893         }
894         group_dead = atomic_dec_and_test(&tsk->signal->live);
895         if (group_dead) {
896                 hrtimer_cancel(&tsk->signal->real_timer);
897                 exit_itimers(tsk->signal);
898         }
899         acct_collect(code, group_dead);
900         if (unlikely(tsk->robust_list))
901                 exit_robust_list(tsk);
902 #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
903         if (unlikely(tsk->compat_robust_list))
904                 compat_exit_robust_list(tsk);
905 #endif
906         if (unlikely(tsk->audit_context))
907                 audit_free(tsk);
908         taskstats_exit_send(tsk, tidstats, group_dead);
909         taskstats_exit_free(tidstats);
910         delayacct_tsk_exit(tsk);
911
912         exit_mm(tsk);
913
914         if (group_dead)
915                 acct_process();
916         exit_sem(tsk);
917         __exit_files(tsk);
918         __exit_fs(tsk);
919         exit_namespace(tsk);
920         exit_thread();
921         cpuset_exit(tsk);
922         exit_keys(tsk);
923
924         if (group_dead && tsk->signal->leader)
925                 disassociate_ctty(1);
926
927         module_put(task_thread_info(tsk)->exec_domain->module);
928         if (tsk->binfmt)
929                 module_put(tsk->binfmt->module);
930
931         tsk->exit_code = code;
932         proc_exit_connector(tsk);
933         exit_notify(tsk);
934 #ifdef CONFIG_NUMA
935         mpol_free(tsk->mempolicy);
936         tsk->mempolicy = NULL;
937 #endif
938         /*
939          * This must happen late, after the PID is not
940          * hashed anymore:
941          */
942         if (unlikely(!list_empty(&tsk->pi_state_list)))
943                 exit_pi_state_list(tsk);
944         if (unlikely(current->pi_state_cache))
945                 kfree(current->pi_state_cache);
946         /*
947          * Make sure we are holding no locks:
948          */
949         debug_check_no_locks_held(tsk);
950
951         if (tsk->io_context)
952                 exit_io_context();
953
954         if (tsk->splice_pipe)
955                 __free_pipe_info(tsk->splice_pipe);
956
957         /* PF_DEAD causes final put_task_struct after we schedule. */
958         preempt_disable();
959         BUG_ON(tsk->flags & PF_DEAD);
960         tsk->flags |= PF_DEAD;
961
962         schedule();
963         BUG();
964         /* Avoid "noreturn function does return".  */
965         for (;;) ;
966 }
967
968 EXPORT_SYMBOL_GPL(do_exit);
969
970 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
971 {
972         if (comp)
973                 complete(comp);
974         
975         do_exit(code);
976 }
977
978 EXPORT_SYMBOL(complete_and_exit);
979
980 asmlinkage long sys_exit(int error_code)
981 {
982         do_exit((error_code&0xff)<<8);
983 }
984
985 /*
986  * Take down every thread in the group.  This is called by fatal signals
987  * as well as by sys_exit_group (below).
988  */
989 NORET_TYPE void
990 do_group_exit(int exit_code)
991 {
992         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
993
994         if (current->signal->flags & SIGNAL_GROUP_EXIT)
995                 exit_code = current->signal->group_exit_code;
996         else if (!thread_group_empty(current)) {
997                 struct signal_struct *const sig = current->signal;
998                 struct sighand_struct *const sighand = current->sighand;
999                 spin_lock_irq(&sighand->siglock);
1000                 if (sig->flags & SIGNAL_GROUP_EXIT)
1001                         /* Another thread got here before we took the lock.  */
1002                         exit_code = sig->group_exit_code;
1003                 else {
1004                         sig->group_exit_code = exit_code;
1005                         zap_other_threads(current);
1006                 }
1007                 spin_unlock_irq(&sighand->siglock);
1008         }
1009
1010         do_exit(exit_code);
1011         /* NOTREACHED */
1012 }
1013
1014 /*
1015  * this kills every thread in the thread group. Note that any externally
1016  * wait4()-ing process will get the correct exit code - even if this
1017  * thread is not the thread group leader.
1018  */
1019 asmlinkage void sys_exit_group(int error_code)
1020 {
1021         do_group_exit((error_code & 0xff) << 8);
1022 }
1023
1024 static int eligible_child(pid_t pid, int options, struct task_struct *p)
1025 {
1026         if (pid > 0) {
1027                 if (p->pid != pid)
1028                         return 0;
1029         } else if (!pid) {
1030                 if (process_group(p) != process_group(current))
1031                         return 0;
1032         } else if (pid != -1) {
1033                 if (process_group(p) != -pid)
1034                         return 0;
1035         }
1036
1037         /*
1038          * Do not consider detached threads that are
1039          * not ptraced:
1040          */
1041         if (p->exit_signal == -1 && !p->ptrace)
1042                 return 0;
1043
1044         /* Wait for all children (clone and not) if __WALL is set;
1045          * otherwise, wait for clone children *only* if __WCLONE is
1046          * set; otherwise, wait for non-clone children *only*.  (Note:
1047          * A "clone" child here is one that reports to its parent
1048          * using a signal other than SIGCHLD.) */
1049         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1050             && !(options & __WALL))
1051                 return 0;
1052         /*
1053          * Do not consider thread group leaders that are
1054          * in a non-empty thread group:
1055          */
1056         if (current->tgid != p->tgid && delay_group_leader(p))
1057                 return 2;
1058
1059         if (security_task_wait(p))
1060                 return 0;
1061
1062         return 1;
1063 }
1064
1065 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1066                                int why, int status,
1067                                struct siginfo __user *infop,
1068                                struct rusage __user *rusagep)
1069 {
1070         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1071
1072         put_task_struct(p);
1073         if (!retval)
1074                 retval = put_user(SIGCHLD, &infop->si_signo);
1075         if (!retval)
1076                 retval = put_user(0, &infop->si_errno);
1077         if (!retval)
1078                 retval = put_user((short)why, &infop->si_code);
1079         if (!retval)
1080                 retval = put_user(pid, &infop->si_pid);
1081         if (!retval)
1082                 retval = put_user(uid, &infop->si_uid);
1083         if (!retval)
1084                 retval = put_user(status, &infop->si_status);
1085         if (!retval)
1086                 retval = pid;
1087         return retval;
1088 }
1089
1090 /*
1091  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1092  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1093  * the lock and this task is uninteresting.  If we return nonzero, we have
1094  * released the lock and the system call should return.
1095  */
1096 static int wait_task_zombie(struct task_struct *p, int noreap,
1097                             struct siginfo __user *infop,
1098                             int __user *stat_addr, struct rusage __user *ru)
1099 {
1100         unsigned long state;
1101         int retval;
1102         int status;
1103
1104         if (unlikely(noreap)) {
1105                 pid_t pid = p->pid;
1106                 uid_t uid = p->uid;
1107                 int exit_code = p->exit_code;
1108                 int why, status;
1109
1110                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1111                         return 0;
1112                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1113                         return 0;
1114                 get_task_struct(p);
1115                 read_unlock(&tasklist_lock);
1116                 if ((exit_code & 0x7f) == 0) {
1117                         why = CLD_EXITED;
1118                         status = exit_code >> 8;
1119                 } else {
1120                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1121                         status = exit_code & 0x7f;
1122                 }
1123                 return wait_noreap_copyout(p, pid, uid, why,
1124                                            status, infop, ru);
1125         }
1126
1127         /*
1128          * Try to move the task's state to DEAD
1129          * only one thread is allowed to do this:
1130          */
1131         state = xchg(&p->exit_state, EXIT_DEAD);
1132         if (state != EXIT_ZOMBIE) {
1133                 BUG_ON(state != EXIT_DEAD);
1134                 return 0;
1135         }
1136         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1137                 /*
1138                  * This can only happen in a race with a ptraced thread
1139                  * dying on another processor.
1140                  */
1141                 return 0;
1142         }
1143
1144         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1145                 struct signal_struct *psig;
1146                 struct signal_struct *sig;
1147
1148                 /*
1149                  * The resource counters for the group leader are in its
1150                  * own task_struct.  Those for dead threads in the group
1151                  * are in its signal_struct, as are those for the child
1152                  * processes it has previously reaped.  All these
1153                  * accumulate in the parent's signal_struct c* fields.
1154                  *
1155                  * We don't bother to take a lock here to protect these
1156                  * p->signal fields, because they are only touched by
1157                  * __exit_signal, which runs with tasklist_lock
1158                  * write-locked anyway, and so is excluded here.  We do
1159                  * need to protect the access to p->parent->signal fields,
1160                  * as other threads in the parent group can be right
1161                  * here reaping other children at the same time.
1162                  */
1163                 spin_lock_irq(&p->parent->sighand->siglock);
1164                 psig = p->parent->signal;
1165                 sig = p->signal;
1166                 psig->cutime =
1167                         cputime_add(psig->cutime,
1168                         cputime_add(p->utime,
1169                         cputime_add(sig->utime,
1170                                     sig->cutime)));
1171                 psig->cstime =
1172                         cputime_add(psig->cstime,
1173                         cputime_add(p->stime,
1174                         cputime_add(sig->stime,
1175                                     sig->cstime)));
1176                 psig->cmin_flt +=
1177                         p->min_flt + sig->min_flt + sig->cmin_flt;
1178                 psig->cmaj_flt +=
1179                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1180                 psig->cnvcsw +=
1181                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1182                 psig->cnivcsw +=
1183                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1184                 spin_unlock_irq(&p->parent->sighand->siglock);
1185         }
1186
1187         /*
1188          * Now we are sure this task is interesting, and no other
1189          * thread can reap it because we set its state to EXIT_DEAD.
1190          */
1191         read_unlock(&tasklist_lock);
1192
1193         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1194         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1195                 ? p->signal->group_exit_code : p->exit_code;
1196         if (!retval && stat_addr)
1197                 retval = put_user(status, stat_addr);
1198         if (!retval && infop)
1199                 retval = put_user(SIGCHLD, &infop->si_signo);
1200         if (!retval && infop)
1201                 retval = put_user(0, &infop->si_errno);
1202         if (!retval && infop) {
1203                 int why;
1204
1205                 if ((status & 0x7f) == 0) {
1206                         why = CLD_EXITED;
1207                         status >>= 8;
1208                 } else {
1209                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1210                         status &= 0x7f;
1211                 }
1212                 retval = put_user((short)why, &infop->si_code);
1213                 if (!retval)
1214                         retval = put_user(status, &infop->si_status);
1215         }
1216         if (!retval && infop)
1217                 retval = put_user(p->pid, &infop->si_pid);
1218         if (!retval && infop)
1219                 retval = put_user(p->uid, &infop->si_uid);
1220         if (retval) {
1221                 // TODO: is this safe?
1222                 p->exit_state = EXIT_ZOMBIE;
1223                 return retval;
1224         }
1225         retval = p->pid;
1226         if (p->real_parent != p->parent) {
1227                 write_lock_irq(&tasklist_lock);
1228                 /* Double-check with lock held.  */
1229                 if (p->real_parent != p->parent) {
1230                         __ptrace_unlink(p);
1231                         // TODO: is this safe?
1232                         p->exit_state = EXIT_ZOMBIE;
1233                         /*
1234                          * If this is not a detached task, notify the parent.
1235                          * If it's still not detached after that, don't release
1236                          * it now.
1237                          */
1238                         if (p->exit_signal != -1) {
1239                                 do_notify_parent(p, p->exit_signal);
1240                                 if (p->exit_signal != -1)
1241                                         p = NULL;
1242                         }
1243                 }
1244                 write_unlock_irq(&tasklist_lock);
1245         }
1246         if (p != NULL)
1247                 release_task(p);
1248         BUG_ON(!retval);
1249         return retval;
1250 }
1251
1252 /*
1253  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1254  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1255  * the lock and this task is uninteresting.  If we return nonzero, we have
1256  * released the lock and the system call should return.
1257  */
1258 static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1259                              int noreap, struct siginfo __user *infop,
1260                              int __user *stat_addr, struct rusage __user *ru)
1261 {
1262         int retval, exit_code;
1263
1264         if (!p->exit_code)
1265                 return 0;
1266         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1267             p->signal && p->signal->group_stop_count > 0)
1268                 /*
1269                  * A group stop is in progress and this is the group leader.
1270                  * We won't report until all threads have stopped.
1271                  */
1272                 return 0;
1273
1274         /*
1275          * Now we are pretty sure this task is interesting.
1276          * Make sure it doesn't get reaped out from under us while we
1277          * give up the lock and then examine it below.  We don't want to
1278          * keep holding onto the tasklist_lock while we call getrusage and
1279          * possibly take page faults for user memory.
1280          */
1281         get_task_struct(p);
1282         read_unlock(&tasklist_lock);
1283
1284         if (unlikely(noreap)) {
1285                 pid_t pid = p->pid;
1286                 uid_t uid = p->uid;
1287                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1288
1289                 exit_code = p->exit_code;
1290                 if (unlikely(!exit_code) ||
1291                     unlikely(p->state & TASK_TRACED))
1292                         goto bail_ref;
1293                 return wait_noreap_copyout(p, pid, uid,
1294                                            why, (exit_code << 8) | 0x7f,
1295                                            infop, ru);
1296         }
1297
1298         write_lock_irq(&tasklist_lock);
1299
1300         /*
1301          * This uses xchg to be atomic with the thread resuming and setting
1302          * it.  It must also be done with the write lock held to prevent a
1303          * race with the EXIT_ZOMBIE case.
1304          */
1305         exit_code = xchg(&p->exit_code, 0);
1306         if (unlikely(p->exit_state)) {
1307                 /*
1308                  * The task resumed and then died.  Let the next iteration
1309                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1310                  * already be zero here if it resumed and did _exit(0).
1311                  * The task itself is dead and won't touch exit_code again;
1312                  * other processors in this function are locked out.
1313                  */
1314                 p->exit_code = exit_code;
1315                 exit_code = 0;
1316         }
1317         if (unlikely(exit_code == 0)) {
1318                 /*
1319                  * Another thread in this function got to it first, or it
1320                  * resumed, or it resumed and then died.
1321                  */
1322                 write_unlock_irq(&tasklist_lock);
1323 bail_ref:
1324                 put_task_struct(p);
1325                 /*
1326                  * We are returning to the wait loop without having successfully
1327                  * removed the process and having released the lock. We cannot
1328                  * continue, since the "p" task pointer is potentially stale.
1329                  *
1330                  * Return -EAGAIN, and do_wait() will restart the loop from the
1331                  * beginning. Do _not_ re-acquire the lock.
1332                  */
1333                 return -EAGAIN;
1334         }
1335
1336         /* move to end of parent's list to avoid starvation */
1337         remove_parent(p);
1338         add_parent(p);
1339
1340         write_unlock_irq(&tasklist_lock);
1341
1342         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1343         if (!retval && stat_addr)
1344                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1345         if (!retval && infop)
1346                 retval = put_user(SIGCHLD, &infop->si_signo);
1347         if (!retval && infop)
1348                 retval = put_user(0, &infop->si_errno);
1349         if (!retval && infop)
1350                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1351                                           ? CLD_TRAPPED : CLD_STOPPED),
1352                                   &infop->si_code);
1353         if (!retval && infop)
1354                 retval = put_user(exit_code, &infop->si_status);
1355         if (!retval && infop)
1356                 retval = put_user(p->pid, &infop->si_pid);
1357         if (!retval && infop)
1358                 retval = put_user(p->uid, &infop->si_uid);
1359         if (!retval)
1360                 retval = p->pid;
1361         put_task_struct(p);
1362
1363         BUG_ON(!retval);
1364         return retval;
1365 }
1366
1367 /*
1368  * Handle do_wait work for one task in a live, non-stopped state.
1369  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1370  * the lock and this task is uninteresting.  If we return nonzero, we have
1371  * released the lock and the system call should return.
1372  */
1373 static int wait_task_continued(struct task_struct *p, int noreap,
1374                                struct siginfo __user *infop,
1375                                int __user *stat_addr, struct rusage __user *ru)
1376 {
1377         int retval;
1378         pid_t pid;
1379         uid_t uid;
1380
1381         if (unlikely(!p->signal))
1382                 return 0;
1383
1384         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1385                 return 0;
1386
1387         spin_lock_irq(&p->sighand->siglock);
1388         /* Re-check with the lock held.  */
1389         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1390                 spin_unlock_irq(&p->sighand->siglock);
1391                 return 0;
1392         }
1393         if (!noreap)
1394                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1395         spin_unlock_irq(&p->sighand->siglock);
1396
1397         pid = p->pid;
1398         uid = p->uid;
1399         get_task_struct(p);
1400         read_unlock(&tasklist_lock);
1401
1402         if (!infop) {
1403                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1404                 put_task_struct(p);
1405                 if (!retval && stat_addr)
1406                         retval = put_user(0xffff, stat_addr);
1407                 if (!retval)
1408                         retval = p->pid;
1409         } else {
1410                 retval = wait_noreap_copyout(p, pid, uid,
1411                                              CLD_CONTINUED, SIGCONT,
1412                                              infop, ru);
1413                 BUG_ON(retval == 0);
1414         }
1415
1416         return retval;
1417 }
1418
1419
1420 static inline int my_ptrace_child(struct task_struct *p)
1421 {
1422         if (!(p->ptrace & PT_PTRACED))
1423                 return 0;
1424         if (!(p->ptrace & PT_ATTACHED))
1425                 return 1;
1426         /*
1427          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1428          * we are the attacher.  If we are the real parent, this is a race
1429          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1430          * which we have to switch the parent links, but has already set
1431          * the flags in p->ptrace.
1432          */
1433         return (p->parent != p->real_parent);
1434 }
1435
1436 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1437                     int __user *stat_addr, struct rusage __user *ru)
1438 {
1439         DECLARE_WAITQUEUE(wait, current);
1440         struct task_struct *tsk;
1441         int flag, retval;
1442
1443         add_wait_queue(&current->signal->wait_chldexit,&wait);
1444 repeat:
1445         /*
1446          * We will set this flag if we see any child that might later
1447          * match our criteria, even if we are not able to reap it yet.
1448          */
1449         flag = 0;
1450         current->state = TASK_INTERRUPTIBLE;
1451         read_lock(&tasklist_lock);
1452         tsk = current;
1453         do {
1454                 struct task_struct *p;
1455                 struct list_head *_p;
1456                 int ret;
1457
1458                 list_for_each(_p,&tsk->children) {
1459                         p = list_entry(_p, struct task_struct, sibling);
1460
1461                         ret = eligible_child(pid, options, p);
1462                         if (!ret)
1463                                 continue;
1464
1465                         switch (p->state) {
1466                         case TASK_TRACED:
1467                                 /*
1468                                  * When we hit the race with PTRACE_ATTACH,
1469                                  * we will not report this child.  But the
1470                                  * race means it has not yet been moved to
1471                                  * our ptrace_children list, so we need to
1472                                  * set the flag here to avoid a spurious ECHILD
1473                                  * when the race happens with the only child.
1474                                  */
1475                                 flag = 1;
1476                                 if (!my_ptrace_child(p))
1477                                         continue;
1478                                 /*FALLTHROUGH*/
1479                         case TASK_STOPPED:
1480                                 /*
1481                                  * It's stopped now, so it might later
1482                                  * continue, exit, or stop again.
1483                                  */
1484                                 flag = 1;
1485                                 if (!(options & WUNTRACED) &&
1486                                     !my_ptrace_child(p))
1487                                         continue;
1488                                 retval = wait_task_stopped(p, ret == 2,
1489                                                            (options & WNOWAIT),
1490                                                            infop,
1491                                                            stat_addr, ru);
1492                                 if (retval == -EAGAIN)
1493                                         goto repeat;
1494                                 if (retval != 0) /* He released the lock.  */
1495                                         goto end;
1496                                 break;
1497                         default:
1498                         // case EXIT_DEAD:
1499                                 if (p->exit_state == EXIT_DEAD)
1500                                         continue;
1501                         // case EXIT_ZOMBIE:
1502                                 if (p->exit_state == EXIT_ZOMBIE) {
1503                                         /*
1504                                          * Eligible but we cannot release
1505                                          * it yet:
1506                                          */
1507                                         if (ret == 2)
1508                                                 goto check_continued;
1509                                         if (!likely(options & WEXITED))
1510                                                 continue;
1511                                         retval = wait_task_zombie(
1512                                                 p, (options & WNOWAIT),
1513                                                 infop, stat_addr, ru);
1514                                         /* He released the lock.  */
1515                                         if (retval != 0)
1516                                                 goto end;
1517                                         break;
1518                                 }
1519 check_continued:
1520                                 /*
1521                                  * It's running now, so it might later
1522                                  * exit, stop, or stop and then continue.
1523                                  */
1524                                 flag = 1;
1525                                 if (!unlikely(options & WCONTINUED))
1526                                         continue;
1527                                 retval = wait_task_continued(
1528                                         p, (options & WNOWAIT),
1529                                         infop, stat_addr, ru);
1530                                 if (retval != 0) /* He released the lock.  */
1531                                         goto end;
1532                                 break;
1533                         }
1534                 }
1535                 if (!flag) {
1536                         list_for_each(_p, &tsk->ptrace_children) {
1537                                 p = list_entry(_p, struct task_struct,
1538                                                 ptrace_list);
1539                                 if (!eligible_child(pid, options, p))
1540                                         continue;
1541                                 flag = 1;
1542                                 break;
1543                         }
1544                 }
1545                 if (options & __WNOTHREAD)
1546                         break;
1547                 tsk = next_thread(tsk);
1548                 BUG_ON(tsk->signal != current->signal);
1549         } while (tsk != current);
1550
1551         read_unlock(&tasklist_lock);
1552         if (flag) {
1553                 retval = 0;
1554                 if (options & WNOHANG)
1555                         goto end;
1556                 retval = -ERESTARTSYS;
1557                 if (signal_pending(current))
1558                         goto end;
1559                 schedule();
1560                 goto repeat;
1561         }
1562         retval = -ECHILD;
1563 end:
1564         current->state = TASK_RUNNING;
1565         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1566         if (infop) {
1567                 if (retval > 0)
1568                 retval = 0;
1569                 else {
1570                         /*
1571                          * For a WNOHANG return, clear out all the fields
1572                          * we would set so the user can easily tell the
1573                          * difference.
1574                          */
1575                         if (!retval)
1576                                 retval = put_user(0, &infop->si_signo);
1577                         if (!retval)
1578                                 retval = put_user(0, &infop->si_errno);
1579                         if (!retval)
1580                                 retval = put_user(0, &infop->si_code);
1581                         if (!retval)
1582                                 retval = put_user(0, &infop->si_pid);
1583                         if (!retval)
1584                                 retval = put_user(0, &infop->si_uid);
1585                         if (!retval)
1586                                 retval = put_user(0, &infop->si_status);
1587                 }
1588         }
1589         return retval;
1590 }
1591
1592 asmlinkage long sys_waitid(int which, pid_t pid,
1593                            struct siginfo __user *infop, int options,
1594                            struct rusage __user *ru)
1595 {
1596         long ret;
1597
1598         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1599                 return -EINVAL;
1600         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1601                 return -EINVAL;
1602
1603         switch (which) {
1604         case P_ALL:
1605                 pid = -1;
1606                 break;
1607         case P_PID:
1608                 if (pid <= 0)
1609                         return -EINVAL;
1610                 break;
1611         case P_PGID:
1612                 if (pid <= 0)
1613                         return -EINVAL;
1614                 pid = -pid;
1615                 break;
1616         default:
1617                 return -EINVAL;
1618         }
1619
1620         ret = do_wait(pid, options, infop, NULL, ru);
1621
1622         /* avoid REGPARM breakage on x86: */
1623         prevent_tail_call(ret);
1624         return ret;
1625 }
1626
1627 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1628                           int options, struct rusage __user *ru)
1629 {
1630         long ret;
1631
1632         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1633                         __WNOTHREAD|__WCLONE|__WALL))
1634                 return -EINVAL;
1635         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1636
1637         /* avoid REGPARM breakage on x86: */
1638         prevent_tail_call(ret);
1639         return ret;
1640 }
1641
1642 #ifdef __ARCH_WANT_SYS_WAITPID
1643
1644 /*
1645  * sys_waitpid() remains for compatibility. waitpid() should be
1646  * implemented by calling sys_wait4() from libc.a.
1647  */
1648 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1649 {
1650         return sys_wait4(pid, stat_addr, options, NULL);
1651 }
1652
1653 #endif