4897977a1f4b950b98672782826fa80df34ba15a
[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/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/cpuset.h>
29 #include <linux/syscalls.h>
30 #include <linux/signal.h>
31
32 #include <asm/uaccess.h>
33 #include <asm/unistd.h>
34 #include <asm/pgtable.h>
35 #include <asm/mmu_context.h>
36
37 extern void sem_exit (void);
38 extern struct task_struct *child_reaper;
39
40 int getrusage(struct task_struct *, int, struct rusage __user *);
41
42 static void exit_mm(struct task_struct * tsk);
43
44 static void __unhash_process(struct task_struct *p)
45 {
46         nr_threads--;
47         detach_pid(p, PIDTYPE_PID);
48         detach_pid(p, PIDTYPE_TGID);
49         if (thread_group_leader(p)) {
50                 detach_pid(p, PIDTYPE_PGID);
51                 detach_pid(p, PIDTYPE_SID);
52                 if (p->pid)
53                         __get_cpu_var(process_counts)--;
54         }
55
56         REMOVE_LINKS(p);
57 }
58
59 void release_task(struct task_struct * p)
60 {
61         int zap_leader;
62         task_t *leader;
63         struct dentry *proc_dentry;
64
65 repeat: 
66         atomic_dec(&p->user->processes);
67         spin_lock(&p->proc_lock);
68         proc_dentry = proc_pid_unhash(p);
69         write_lock_irq(&tasklist_lock);
70         if (unlikely(p->ptrace))
71                 __ptrace_unlink(p);
72         BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
73         __exit_signal(p);
74         __exit_sighand(p);
75         /*
76          * Note that the fastpath in sys_times depends on __exit_signal having
77          * updated the counters before a task is removed from the tasklist of
78          * the process by __unhash_process.
79          */
80         __unhash_process(p);
81
82         /*
83          * If we are the last non-leader member of the thread
84          * group, and the leader is zombie, then notify the
85          * group leader's parent process. (if it wants notification.)
86          */
87         zap_leader = 0;
88         leader = p->group_leader;
89         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
90                 BUG_ON(leader->exit_signal == -1);
91                 do_notify_parent(leader, leader->exit_signal);
92                 /*
93                  * If we were the last child thread and the leader has
94                  * exited already, and the leader's parent ignores SIGCHLD,
95                  * then we are the one who should release the leader.
96                  *
97                  * do_notify_parent() will have marked it self-reaping in
98                  * that case.
99                  */
100                 zap_leader = (leader->exit_signal == -1);
101         }
102
103         sched_exit(p);
104         write_unlock_irq(&tasklist_lock);
105         spin_unlock(&p->proc_lock);
106         proc_pid_flush(proc_dentry);
107         release_thread(p);
108         put_task_struct(p);
109
110         p = leader;
111         if (unlikely(zap_leader))
112                 goto repeat;
113 }
114
115 /* we are using it only for SMP init */
116
117 void unhash_process(struct task_struct *p)
118 {
119         struct dentry *proc_dentry;
120
121         spin_lock(&p->proc_lock);
122         proc_dentry = proc_pid_unhash(p);
123         write_lock_irq(&tasklist_lock);
124         __unhash_process(p);
125         write_unlock_irq(&tasklist_lock);
126         spin_unlock(&p->proc_lock);
127         proc_pid_flush(proc_dentry);
128 }
129
130 /*
131  * This checks not only the pgrp, but falls back on the pid if no
132  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
133  * without this...
134  */
135 int session_of_pgrp(int pgrp)
136 {
137         struct task_struct *p;
138         int sid = -1;
139
140         read_lock(&tasklist_lock);
141         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
142                 if (p->signal->session > 0) {
143                         sid = p->signal->session;
144                         goto out;
145                 }
146         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
147         p = find_task_by_pid(pgrp);
148         if (p)
149                 sid = p->signal->session;
150 out:
151         read_unlock(&tasklist_lock);
152         
153         return sid;
154 }
155
156 /*
157  * Determine if a process group is "orphaned", according to the POSIX
158  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
159  * by terminal-generated stop signals.  Newly orphaned process groups are
160  * to receive a SIGHUP and a SIGCONT.
161  *
162  * "I ask you, have you ever known what it is to be an orphan?"
163  */
164 static int will_become_orphaned_pgrp(int pgrp, task_t *ignored_task)
165 {
166         struct task_struct *p;
167         int ret = 1;
168
169         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
170                 if (p == ignored_task
171                                 || p->exit_state
172                                 || p->real_parent->pid == 1)
173                         continue;
174                 if (process_group(p->real_parent) != pgrp
175                             && p->real_parent->signal->session == p->signal->session) {
176                         ret = 0;
177                         break;
178                 }
179         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
180         return ret;     /* (sighing) "Often!" */
181 }
182
183 int is_orphaned_pgrp(int pgrp)
184 {
185         int retval;
186
187         read_lock(&tasklist_lock);
188         retval = will_become_orphaned_pgrp(pgrp, NULL);
189         read_unlock(&tasklist_lock);
190
191         return retval;
192 }
193
194 static inline int has_stopped_jobs(int pgrp)
195 {
196         int retval = 0;
197         struct task_struct *p;
198
199         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
200                 if (p->state != TASK_STOPPED)
201                         continue;
202
203                 /* If p is stopped by a debugger on a signal that won't
204                    stop it, then don't count p as stopped.  This isn't
205                    perfect but it's a good approximation.  */
206                 if (unlikely (p->ptrace)
207                     && p->exit_code != SIGSTOP
208                     && p->exit_code != SIGTSTP
209                     && p->exit_code != SIGTTOU
210                     && p->exit_code != SIGTTIN)
211                         continue;
212
213                 retval = 1;
214                 break;
215         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
216         return retval;
217 }
218
219 /**
220  * reparent_to_init - Reparent the calling kernel thread to the init task.
221  *
222  * If a kernel thread is launched as a result of a system call, or if
223  * it ever exits, it should generally reparent itself to init so that
224  * it is correctly cleaned up on exit.
225  *
226  * The various task state such as scheduling policy and priority may have
227  * been inherited from a user process, so we reset them to sane values here.
228  *
229  * NOTE that reparent_to_init() gives the caller full capabilities.
230  */
231 static inline void reparent_to_init(void)
232 {
233         write_lock_irq(&tasklist_lock);
234
235         ptrace_unlink(current);
236         /* Reparent to init */
237         REMOVE_LINKS(current);
238         current->parent = child_reaper;
239         current->real_parent = child_reaper;
240         SET_LINKS(current);
241
242         /* Set the exit signal to SIGCHLD so we signal init on exit */
243         current->exit_signal = SIGCHLD;
244
245         if ((current->policy == SCHED_NORMAL) && (task_nice(current) < 0))
246                 set_user_nice(current, 0);
247         /* cpus_allowed? */
248         /* rt_priority? */
249         /* signals? */
250         security_task_reparent_to_init(current);
251         memcpy(current->signal->rlim, init_task.signal->rlim,
252                sizeof(current->signal->rlim));
253         atomic_inc(&(INIT_USER->__count));
254         write_unlock_irq(&tasklist_lock);
255         switch_uid(INIT_USER);
256 }
257
258 void __set_special_pids(pid_t session, pid_t pgrp)
259 {
260         struct task_struct *curr = current;
261
262         if (curr->signal->session != session) {
263                 detach_pid(curr, PIDTYPE_SID);
264                 curr->signal->session = session;
265                 attach_pid(curr, PIDTYPE_SID, session);
266         }
267         if (process_group(curr) != pgrp) {
268                 detach_pid(curr, PIDTYPE_PGID);
269                 curr->signal->pgrp = pgrp;
270                 attach_pid(curr, PIDTYPE_PGID, pgrp);
271         }
272 }
273
274 void set_special_pids(pid_t session, pid_t pgrp)
275 {
276         write_lock_irq(&tasklist_lock);
277         __set_special_pids(session, pgrp);
278         write_unlock_irq(&tasklist_lock);
279 }
280
281 /*
282  * Let kernel threads use this to say that they
283  * allow a certain signal (since daemonize() will
284  * have disabled all of them by default).
285  */
286 int allow_signal(int sig)
287 {
288         if (!valid_signal(sig) || sig < 1)
289                 return -EINVAL;
290
291         spin_lock_irq(&current->sighand->siglock);
292         sigdelset(&current->blocked, sig);
293         if (!current->mm) {
294                 /* Kernel threads handle their own signals.
295                    Let the signal code know it'll be handled, so
296                    that they don't get converted to SIGKILL or
297                    just silently dropped */
298                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
299         }
300         recalc_sigpending();
301         spin_unlock_irq(&current->sighand->siglock);
302         return 0;
303 }
304
305 EXPORT_SYMBOL(allow_signal);
306
307 int disallow_signal(int sig)
308 {
309         if (!valid_signal(sig) || sig < 1)
310                 return -EINVAL;
311
312         spin_lock_irq(&current->sighand->siglock);
313         sigaddset(&current->blocked, sig);
314         recalc_sigpending();
315         spin_unlock_irq(&current->sighand->siglock);
316         return 0;
317 }
318
319 EXPORT_SYMBOL(disallow_signal);
320
321 /*
322  *      Put all the gunge required to become a kernel thread without
323  *      attached user resources in one place where it belongs.
324  */
325
326 void daemonize(const char *name, ...)
327 {
328         va_list args;
329         struct fs_struct *fs;
330         sigset_t blocked;
331
332         va_start(args, name);
333         vsnprintf(current->comm, sizeof(current->comm), name, args);
334         va_end(args);
335
336         /*
337          * If we were started as result of loading a module, close all of the
338          * user space pages.  We don't need them, and if we didn't close them
339          * they would be locked into memory.
340          */
341         exit_mm(current);
342
343         set_special_pids(1, 1);
344         down(&tty_sem);
345         current->signal->tty = NULL;
346         up(&tty_sem);
347
348         /* Block and flush all signals */
349         sigfillset(&blocked);
350         sigprocmask(SIG_BLOCK, &blocked, NULL);
351         flush_signals(current);
352
353         /* Become as one with the init task */
354
355         exit_fs(current);       /* current->fs->count--; */
356         fs = init_task.fs;
357         current->fs = fs;
358         atomic_inc(&fs->count);
359         exit_files(current);
360         current->files = init_task.files;
361         atomic_inc(&current->files->count);
362
363         reparent_to_init();
364 }
365
366 EXPORT_SYMBOL(daemonize);
367
368 static inline void close_files(struct files_struct * files)
369 {
370         int i, j;
371         struct fdtable *fdt;
372
373         j = 0;
374
375         /*
376          * It is safe to dereference the fd table without RCU or
377          * ->file_lock because this is the last reference to the
378          * files structure.
379          */
380         fdt = files_fdtable(files);
381         for (;;) {
382                 unsigned long set;
383                 i = j * __NFDBITS;
384                 if (i >= fdt->max_fdset || i >= fdt->max_fds)
385                         break;
386                 set = fdt->open_fds->fds_bits[j++];
387                 while (set) {
388                         if (set & 1) {
389                                 struct file * file = xchg(&fdt->fd[i], NULL);
390                                 if (file)
391                                         filp_close(file, files);
392                         }
393                         i++;
394                         set >>= 1;
395                 }
396         }
397 }
398
399 struct files_struct *get_files_struct(struct task_struct *task)
400 {
401         struct files_struct *files;
402
403         task_lock(task);
404         files = task->files;
405         if (files)
406                 atomic_inc(&files->count);
407         task_unlock(task);
408
409         return files;
410 }
411
412 void fastcall put_files_struct(struct files_struct *files)
413 {
414         struct fdtable *fdt;
415
416         if (atomic_dec_and_test(&files->count)) {
417                 close_files(files);
418                 /*
419                  * Free the fd and fdset arrays if we expanded them.
420                  * If the fdtable was embedded, pass files for freeing
421                  * at the end of the RCU grace period. Otherwise,
422                  * you can free files immediately.
423                  */
424                 fdt = files_fdtable(files);
425                 if (fdt == &files->fdtab)
426                         fdt->free_files = files;
427                 else
428                         kmem_cache_free(files_cachep, files);
429                 free_fdtable(fdt);
430         }
431 }
432
433 EXPORT_SYMBOL(put_files_struct);
434
435 static inline void __exit_files(struct task_struct *tsk)
436 {
437         struct files_struct * files = tsk->files;
438
439         if (files) {
440                 task_lock(tsk);
441                 tsk->files = NULL;
442                 task_unlock(tsk);
443                 put_files_struct(files);
444         }
445 }
446
447 void exit_files(struct task_struct *tsk)
448 {
449         __exit_files(tsk);
450 }
451
452 static inline void __put_fs_struct(struct fs_struct *fs)
453 {
454         /* No need to hold fs->lock if we are killing it */
455         if (atomic_dec_and_test(&fs->count)) {
456                 dput(fs->root);
457                 mntput(fs->rootmnt);
458                 dput(fs->pwd);
459                 mntput(fs->pwdmnt);
460                 if (fs->altroot) {
461                         dput(fs->altroot);
462                         mntput(fs->altrootmnt);
463                 }
464                 kmem_cache_free(fs_cachep, fs);
465         }
466 }
467
468 void put_fs_struct(struct fs_struct *fs)
469 {
470         __put_fs_struct(fs);
471 }
472
473 static inline void __exit_fs(struct task_struct *tsk)
474 {
475         struct fs_struct * fs = tsk->fs;
476
477         if (fs) {
478                 task_lock(tsk);
479                 tsk->fs = NULL;
480                 task_unlock(tsk);
481                 __put_fs_struct(fs);
482         }
483 }
484
485 void exit_fs(struct task_struct *tsk)
486 {
487         __exit_fs(tsk);
488 }
489
490 EXPORT_SYMBOL_GPL(exit_fs);
491
492 /*
493  * Turn us into a lazy TLB process if we
494  * aren't already..
495  */
496 static void exit_mm(struct task_struct * tsk)
497 {
498         struct mm_struct *mm = tsk->mm;
499
500         mm_release(tsk, mm);
501         if (!mm)
502                 return;
503         /*
504          * Serialize with any possible pending coredump.
505          * We must hold mmap_sem around checking core_waiters
506          * and clearing tsk->mm.  The core-inducing thread
507          * will increment core_waiters for each thread in the
508          * group with ->mm != NULL.
509          */
510         down_read(&mm->mmap_sem);
511         if (mm->core_waiters) {
512                 up_read(&mm->mmap_sem);
513                 down_write(&mm->mmap_sem);
514                 if (!--mm->core_waiters)
515                         complete(mm->core_startup_done);
516                 up_write(&mm->mmap_sem);
517
518                 wait_for_completion(&mm->core_done);
519                 down_read(&mm->mmap_sem);
520         }
521         atomic_inc(&mm->mm_count);
522         if (mm != tsk->active_mm) BUG();
523         /* more a memory barrier than a real lock */
524         task_lock(tsk);
525         tsk->mm = NULL;
526         up_read(&mm->mmap_sem);
527         enter_lazy_tlb(mm, current);
528         task_unlock(tsk);
529         mmput(mm);
530 }
531
532 static inline void choose_new_parent(task_t *p, task_t *reaper, task_t *child_reaper)
533 {
534         /*
535          * Make sure we're not reparenting to ourselves and that
536          * the parent is not a zombie.
537          */
538         BUG_ON(p == reaper || reaper->exit_state >= EXIT_ZOMBIE);
539         p->real_parent = reaper;
540 }
541
542 static inline void reparent_thread(task_t *p, task_t *father, int traced)
543 {
544         /* We don't want people slaying init.  */
545         if (p->exit_signal != -1)
546                 p->exit_signal = SIGCHLD;
547
548         if (p->pdeath_signal)
549                 /* We already hold the tasklist_lock here.  */
550                 group_send_sig_info(p->pdeath_signal, (void *) 0, p);
551
552         /* Move the child from its dying parent to the new one.  */
553         if (unlikely(traced)) {
554                 /* Preserve ptrace links if someone else is tracing this child.  */
555                 list_del_init(&p->ptrace_list);
556                 if (p->parent != p->real_parent)
557                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
558         } else {
559                 /* If this child is being traced, then we're the one tracing it
560                  * anyway, so let go of it.
561                  */
562                 p->ptrace = 0;
563                 list_del_init(&p->sibling);
564                 p->parent = p->real_parent;
565                 list_add_tail(&p->sibling, &p->parent->children);
566
567                 /* If we'd notified the old parent about this child's death,
568                  * also notify the new parent.
569                  */
570                 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
571                     thread_group_empty(p))
572                         do_notify_parent(p, p->exit_signal);
573                 else if (p->state == TASK_TRACED) {
574                         /*
575                          * If it was at a trace stop, turn it into
576                          * a normal stop since it's no longer being
577                          * traced.
578                          */
579                         ptrace_untrace(p);
580                 }
581         }
582
583         /*
584          * process group orphan check
585          * Case ii: Our child is in a different pgrp
586          * than we are, and it was the only connection
587          * outside, so the child pgrp is now orphaned.
588          */
589         if ((process_group(p) != process_group(father)) &&
590             (p->signal->session == father->signal->session)) {
591                 int pgrp = process_group(p);
592
593                 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
594                         __kill_pg_info(SIGHUP, (void *)1, pgrp);
595                         __kill_pg_info(SIGCONT, (void *)1, pgrp);
596                 }
597         }
598 }
599
600 /*
601  * When we die, we re-parent all our children.
602  * Try to give them to another thread in our thread
603  * group, and if no such member exists, give it to
604  * the global child reaper process (ie "init")
605  */
606 static inline void forget_original_parent(struct task_struct * father,
607                                           struct list_head *to_release)
608 {
609         struct task_struct *p, *reaper = father;
610         struct list_head *_p, *_n;
611
612         do {
613                 reaper = next_thread(reaper);
614                 if (reaper == father) {
615                         reaper = child_reaper;
616                         break;
617                 }
618         } while (reaper->exit_state);
619
620         /*
621          * There are only two places where our children can be:
622          *
623          * - in our child list
624          * - in our ptraced child list
625          *
626          * Search them and reparent children.
627          */
628         list_for_each_safe(_p, _n, &father->children) {
629                 int ptrace;
630                 p = list_entry(_p,struct task_struct,sibling);
631
632                 ptrace = p->ptrace;
633
634                 /* if father isn't the real parent, then ptrace must be enabled */
635                 BUG_ON(father != p->real_parent && !ptrace);
636
637                 if (father == p->real_parent) {
638                         /* reparent with a reaper, real father it's us */
639                         choose_new_parent(p, reaper, child_reaper);
640                         reparent_thread(p, father, 0);
641                 } else {
642                         /* reparent ptraced task to its real parent */
643                         __ptrace_unlink (p);
644                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
645                             thread_group_empty(p))
646                                 do_notify_parent(p, p->exit_signal);
647                 }
648
649                 /*
650                  * if the ptraced child is a zombie with exit_signal == -1
651                  * we must collect it before we exit, or it will remain
652                  * zombie forever since we prevented it from self-reap itself
653                  * while it was being traced by us, to be able to see it in wait4.
654                  */
655                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
656                         list_add(&p->ptrace_list, to_release);
657         }
658         list_for_each_safe(_p, _n, &father->ptrace_children) {
659                 p = list_entry(_p,struct task_struct,ptrace_list);
660                 choose_new_parent(p, reaper, child_reaper);
661                 reparent_thread(p, father, 1);
662         }
663 }
664
665 /*
666  * Send signals to all our closest relatives so that they know
667  * to properly mourn us..
668  */
669 static void exit_notify(struct task_struct *tsk)
670 {
671         int state;
672         struct task_struct *t;
673         struct list_head ptrace_dead, *_p, *_n;
674
675         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
676             && !thread_group_empty(tsk)) {
677                 /*
678                  * This occurs when there was a race between our exit
679                  * syscall and a group signal choosing us as the one to
680                  * wake up.  It could be that we are the only thread
681                  * alerted to check for pending signals, but another thread
682                  * should be woken now to take the signal since we will not.
683                  * Now we'll wake all the threads in the group just to make
684                  * sure someone gets all the pending signals.
685                  */
686                 read_lock(&tasklist_lock);
687                 spin_lock_irq(&tsk->sighand->siglock);
688                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
689                         if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
690                                 recalc_sigpending_tsk(t);
691                                 if (signal_pending(t))
692                                         signal_wake_up(t, 0);
693                         }
694                 spin_unlock_irq(&tsk->sighand->siglock);
695                 read_unlock(&tasklist_lock);
696         }
697
698         write_lock_irq(&tasklist_lock);
699
700         /*
701          * This does two things:
702          *
703          * A.  Make init inherit all the child processes
704          * B.  Check to see if any process groups have become orphaned
705          *      as a result of our exiting, and if they have any stopped
706          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
707          */
708
709         INIT_LIST_HEAD(&ptrace_dead);
710         forget_original_parent(tsk, &ptrace_dead);
711         BUG_ON(!list_empty(&tsk->children));
712         BUG_ON(!list_empty(&tsk->ptrace_children));
713
714         /*
715          * Check to see if any process groups have become orphaned
716          * as a result of our exiting, and if they have any stopped
717          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
718          *
719          * Case i: Our father is in a different pgrp than we are
720          * and we were the only connection outside, so our pgrp
721          * is about to become orphaned.
722          */
723          
724         t = tsk->real_parent;
725         
726         if ((process_group(t) != process_group(tsk)) &&
727             (t->signal->session == tsk->signal->session) &&
728             will_become_orphaned_pgrp(process_group(tsk), tsk) &&
729             has_stopped_jobs(process_group(tsk))) {
730                 __kill_pg_info(SIGHUP, (void *)1, process_group(tsk));
731                 __kill_pg_info(SIGCONT, (void *)1, process_group(tsk));
732         }
733
734         /* Let father know we died 
735          *
736          * Thread signals are configurable, but you aren't going to use
737          * that to send signals to arbitary processes. 
738          * That stops right now.
739          *
740          * If the parent exec id doesn't match the exec id we saved
741          * when we started then we know the parent has changed security
742          * domain.
743          *
744          * If our self_exec id doesn't match our parent_exec_id then
745          * we have changed execution domain as these two values started
746          * the same after a fork.
747          *      
748          */
749         
750         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
751             ( tsk->parent_exec_id != t->self_exec_id  ||
752               tsk->self_exec_id != tsk->parent_exec_id)
753             && !capable(CAP_KILL))
754                 tsk->exit_signal = SIGCHLD;
755
756
757         /* If something other than our normal parent is ptracing us, then
758          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
759          * only has special meaning to our real parent.
760          */
761         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
762                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
763                 do_notify_parent(tsk, signal);
764         } else if (tsk->ptrace) {
765                 do_notify_parent(tsk, SIGCHLD);
766         }
767
768         state = EXIT_ZOMBIE;
769         if (tsk->exit_signal == -1 &&
770             (likely(tsk->ptrace == 0) ||
771              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
772                 state = EXIT_DEAD;
773         tsk->exit_state = state;
774
775         write_unlock_irq(&tasklist_lock);
776
777         list_for_each_safe(_p, _n, &ptrace_dead) {
778                 list_del_init(_p);
779                 t = list_entry(_p,struct task_struct,ptrace_list);
780                 release_task(t);
781         }
782
783         /* If the process is dead, release it - nobody will wait for it */
784         if (state == EXIT_DEAD)
785                 release_task(tsk);
786
787         /* PF_DEAD causes final put_task_struct after we schedule. */
788         preempt_disable();
789         tsk->flags |= PF_DEAD;
790 }
791
792 fastcall NORET_TYPE void do_exit(long code)
793 {
794         struct task_struct *tsk = current;
795         int group_dead;
796
797         profile_task_exit(tsk);
798
799         WARN_ON(atomic_read(&tsk->fs_excl));
800
801         if (unlikely(in_interrupt()))
802                 panic("Aiee, killing interrupt handler!");
803         if (unlikely(!tsk->pid))
804                 panic("Attempted to kill the idle task!");
805         if (unlikely(tsk->pid == 1))
806                 panic("Attempted to kill init!");
807         if (tsk->io_context)
808                 exit_io_context();
809
810         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
811                 current->ptrace_message = code;
812                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
813         }
814
815         /*
816          * We're taking recursive faults here in do_exit. Safest is to just
817          * leave this task alone and wait for reboot.
818          */
819         if (unlikely(tsk->flags & PF_EXITING)) {
820                 printk(KERN_ALERT
821                         "Fixing recursive fault but reboot is needed!\n");
822                 set_current_state(TASK_UNINTERRUPTIBLE);
823                 schedule();
824         }
825
826         tsk->flags |= PF_EXITING;
827
828         if (unlikely(in_atomic()))
829                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
830                                 current->comm, current->pid,
831                                 preempt_count());
832
833         acct_update_integrals(tsk);
834         update_mem_hiwater(tsk);
835         group_dead = atomic_dec_and_test(&tsk->signal->live);
836         if (group_dead) {
837                 del_timer_sync(&tsk->signal->real_timer);
838                 exit_itimers(tsk->signal);
839                 acct_process(code);
840         }
841         exit_mm(tsk);
842
843         exit_sem(tsk);
844         __exit_files(tsk);
845         __exit_fs(tsk);
846         exit_namespace(tsk);
847         exit_thread();
848         cpuset_exit(tsk);
849         exit_keys(tsk);
850
851         if (group_dead && tsk->signal->leader)
852                 disassociate_ctty(1);
853
854         module_put(tsk->thread_info->exec_domain->module);
855         if (tsk->binfmt)
856                 module_put(tsk->binfmt->module);
857
858         tsk->exit_code = code;
859         exit_notify(tsk);
860 #ifdef CONFIG_NUMA
861         mpol_free(tsk->mempolicy);
862         tsk->mempolicy = NULL;
863 #endif
864
865         BUG_ON(!(current->flags & PF_DEAD));
866         schedule();
867         BUG();
868         /* Avoid "noreturn function does return".  */
869         for (;;) ;
870 }
871
872 EXPORT_SYMBOL_GPL(do_exit);
873
874 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
875 {
876         if (comp)
877                 complete(comp);
878         
879         do_exit(code);
880 }
881
882 EXPORT_SYMBOL(complete_and_exit);
883
884 asmlinkage long sys_exit(int error_code)
885 {
886         do_exit((error_code&0xff)<<8);
887 }
888
889 task_t fastcall *next_thread(const task_t *p)
890 {
891         return pid_task(p->pids[PIDTYPE_TGID].pid_list.next, PIDTYPE_TGID);
892 }
893
894 EXPORT_SYMBOL(next_thread);
895
896 /*
897  * Take down every thread in the group.  This is called by fatal signals
898  * as well as by sys_exit_group (below).
899  */
900 NORET_TYPE void
901 do_group_exit(int exit_code)
902 {
903         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
904
905         if (current->signal->flags & SIGNAL_GROUP_EXIT)
906                 exit_code = current->signal->group_exit_code;
907         else if (!thread_group_empty(current)) {
908                 struct signal_struct *const sig = current->signal;
909                 struct sighand_struct *const sighand = current->sighand;
910                 read_lock(&tasklist_lock);
911                 spin_lock_irq(&sighand->siglock);
912                 if (sig->flags & SIGNAL_GROUP_EXIT)
913                         /* Another thread got here before we took the lock.  */
914                         exit_code = sig->group_exit_code;
915                 else {
916                         sig->flags = SIGNAL_GROUP_EXIT;
917                         sig->group_exit_code = exit_code;
918                         zap_other_threads(current);
919                 }
920                 spin_unlock_irq(&sighand->siglock);
921                 read_unlock(&tasklist_lock);
922         }
923
924         do_exit(exit_code);
925         /* NOTREACHED */
926 }
927
928 /*
929  * this kills every thread in the thread group. Note that any externally
930  * wait4()-ing process will get the correct exit code - even if this
931  * thread is not the thread group leader.
932  */
933 asmlinkage void sys_exit_group(int error_code)
934 {
935         do_group_exit((error_code & 0xff) << 8);
936 }
937
938 static int eligible_child(pid_t pid, int options, task_t *p)
939 {
940         if (pid > 0) {
941                 if (p->pid != pid)
942                         return 0;
943         } else if (!pid) {
944                 if (process_group(p) != process_group(current))
945                         return 0;
946         } else if (pid != -1) {
947                 if (process_group(p) != -pid)
948                         return 0;
949         }
950
951         /*
952          * Do not consider detached threads that are
953          * not ptraced:
954          */
955         if (p->exit_signal == -1 && !p->ptrace)
956                 return 0;
957
958         /* Wait for all children (clone and not) if __WALL is set;
959          * otherwise, wait for clone children *only* if __WCLONE is
960          * set; otherwise, wait for non-clone children *only*.  (Note:
961          * A "clone" child here is one that reports to its parent
962          * using a signal other than SIGCHLD.) */
963         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
964             && !(options & __WALL))
965                 return 0;
966         /*
967          * Do not consider thread group leaders that are
968          * in a non-empty thread group:
969          */
970         if (current->tgid != p->tgid && delay_group_leader(p))
971                 return 2;
972
973         if (security_task_wait(p))
974                 return 0;
975
976         return 1;
977 }
978
979 static int wait_noreap_copyout(task_t *p, pid_t pid, uid_t uid,
980                                int why, int status,
981                                struct siginfo __user *infop,
982                                struct rusage __user *rusagep)
983 {
984         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
985         put_task_struct(p);
986         if (!retval)
987                 retval = put_user(SIGCHLD, &infop->si_signo);
988         if (!retval)
989                 retval = put_user(0, &infop->si_errno);
990         if (!retval)
991                 retval = put_user((short)why, &infop->si_code);
992         if (!retval)
993                 retval = put_user(pid, &infop->si_pid);
994         if (!retval)
995                 retval = put_user(uid, &infop->si_uid);
996         if (!retval)
997                 retval = put_user(status, &infop->si_status);
998         if (!retval)
999                 retval = pid;
1000         return retval;
1001 }
1002
1003 /*
1004  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1005  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1006  * the lock and this task is uninteresting.  If we return nonzero, we have
1007  * released the lock and the system call should return.
1008  */
1009 static int wait_task_zombie(task_t *p, int noreap,
1010                             struct siginfo __user *infop,
1011                             int __user *stat_addr, struct rusage __user *ru)
1012 {
1013         unsigned long state;
1014         int retval;
1015         int status;
1016
1017         if (unlikely(noreap)) {
1018                 pid_t pid = p->pid;
1019                 uid_t uid = p->uid;
1020                 int exit_code = p->exit_code;
1021                 int why, status;
1022
1023                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1024                         return 0;
1025                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1026                         return 0;
1027                 get_task_struct(p);
1028                 read_unlock(&tasklist_lock);
1029                 if ((exit_code & 0x7f) == 0) {
1030                         why = CLD_EXITED;
1031                         status = exit_code >> 8;
1032                 } else {
1033                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1034                         status = exit_code & 0x7f;
1035                 }
1036                 return wait_noreap_copyout(p, pid, uid, why,
1037                                            status, infop, ru);
1038         }
1039
1040         /*
1041          * Try to move the task's state to DEAD
1042          * only one thread is allowed to do this:
1043          */
1044         state = xchg(&p->exit_state, EXIT_DEAD);
1045         if (state != EXIT_ZOMBIE) {
1046                 BUG_ON(state != EXIT_DEAD);
1047                 return 0;
1048         }
1049         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1050                 /*
1051                  * This can only happen in a race with a ptraced thread
1052                  * dying on another processor.
1053                  */
1054                 return 0;
1055         }
1056
1057         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1058                 /*
1059                  * The resource counters for the group leader are in its
1060                  * own task_struct.  Those for dead threads in the group
1061                  * are in its signal_struct, as are those for the child
1062                  * processes it has previously reaped.  All these
1063                  * accumulate in the parent's signal_struct c* fields.
1064                  *
1065                  * We don't bother to take a lock here to protect these
1066                  * p->signal fields, because they are only touched by
1067                  * __exit_signal, which runs with tasklist_lock
1068                  * write-locked anyway, and so is excluded here.  We do
1069                  * need to protect the access to p->parent->signal fields,
1070                  * as other threads in the parent group can be right
1071                  * here reaping other children at the same time.
1072                  */
1073                 spin_lock_irq(&p->parent->sighand->siglock);
1074                 p->parent->signal->cutime =
1075                         cputime_add(p->parent->signal->cutime,
1076                         cputime_add(p->utime,
1077                         cputime_add(p->signal->utime,
1078                                     p->signal->cutime)));
1079                 p->parent->signal->cstime =
1080                         cputime_add(p->parent->signal->cstime,
1081                         cputime_add(p->stime,
1082                         cputime_add(p->signal->stime,
1083                                     p->signal->cstime)));
1084                 p->parent->signal->cmin_flt +=
1085                         p->min_flt + p->signal->min_flt + p->signal->cmin_flt;
1086                 p->parent->signal->cmaj_flt +=
1087                         p->maj_flt + p->signal->maj_flt + p->signal->cmaj_flt;
1088                 p->parent->signal->cnvcsw +=
1089                         p->nvcsw + p->signal->nvcsw + p->signal->cnvcsw;
1090                 p->parent->signal->cnivcsw +=
1091                         p->nivcsw + p->signal->nivcsw + p->signal->cnivcsw;
1092                 spin_unlock_irq(&p->parent->sighand->siglock);
1093         }
1094
1095         /*
1096          * Now we are sure this task is interesting, and no other
1097          * thread can reap it because we set its state to EXIT_DEAD.
1098          */
1099         read_unlock(&tasklist_lock);
1100
1101         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1102         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1103                 ? p->signal->group_exit_code : p->exit_code;
1104         if (!retval && stat_addr)
1105                 retval = put_user(status, stat_addr);
1106         if (!retval && infop)
1107                 retval = put_user(SIGCHLD, &infop->si_signo);
1108         if (!retval && infop)
1109                 retval = put_user(0, &infop->si_errno);
1110         if (!retval && infop) {
1111                 int why;
1112
1113                 if ((status & 0x7f) == 0) {
1114                         why = CLD_EXITED;
1115                         status >>= 8;
1116                 } else {
1117                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1118                         status &= 0x7f;
1119                 }
1120                 retval = put_user((short)why, &infop->si_code);
1121                 if (!retval)
1122                         retval = put_user(status, &infop->si_status);
1123         }
1124         if (!retval && infop)
1125                 retval = put_user(p->pid, &infop->si_pid);
1126         if (!retval && infop)
1127                 retval = put_user(p->uid, &infop->si_uid);
1128         if (retval) {
1129                 // TODO: is this safe?
1130                 p->exit_state = EXIT_ZOMBIE;
1131                 return retval;
1132         }
1133         retval = p->pid;
1134         if (p->real_parent != p->parent) {
1135                 write_lock_irq(&tasklist_lock);
1136                 /* Double-check with lock held.  */
1137                 if (p->real_parent != p->parent) {
1138                         __ptrace_unlink(p);
1139                         // TODO: is this safe?
1140                         p->exit_state = EXIT_ZOMBIE;
1141                         /*
1142                          * If this is not a detached task, notify the parent.
1143                          * If it's still not detached after that, don't release
1144                          * it now.
1145                          */
1146                         if (p->exit_signal != -1) {
1147                                 do_notify_parent(p, p->exit_signal);
1148                                 if (p->exit_signal != -1)
1149                                         p = NULL;
1150                         }
1151                 }
1152                 write_unlock_irq(&tasklist_lock);
1153         }
1154         if (p != NULL)
1155                 release_task(p);
1156         BUG_ON(!retval);
1157         return retval;
1158 }
1159
1160 /*
1161  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1162  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1163  * the lock and this task is uninteresting.  If we return nonzero, we have
1164  * released the lock and the system call should return.
1165  */
1166 static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap,
1167                              struct siginfo __user *infop,
1168                              int __user *stat_addr, struct rusage __user *ru)
1169 {
1170         int retval, exit_code;
1171
1172         if (!p->exit_code)
1173                 return 0;
1174         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1175             p->signal && p->signal->group_stop_count > 0)
1176                 /*
1177                  * A group stop is in progress and this is the group leader.
1178                  * We won't report until all threads have stopped.
1179                  */
1180                 return 0;
1181
1182         /*
1183          * Now we are pretty sure this task is interesting.
1184          * Make sure it doesn't get reaped out from under us while we
1185          * give up the lock and then examine it below.  We don't want to
1186          * keep holding onto the tasklist_lock while we call getrusage and
1187          * possibly take page faults for user memory.
1188          */
1189         get_task_struct(p);
1190         read_unlock(&tasklist_lock);
1191
1192         if (unlikely(noreap)) {
1193                 pid_t pid = p->pid;
1194                 uid_t uid = p->uid;
1195                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1196
1197                 exit_code = p->exit_code;
1198                 if (unlikely(!exit_code) ||
1199                     unlikely(p->state & TASK_TRACED))
1200                         goto bail_ref;
1201                 return wait_noreap_copyout(p, pid, uid,
1202                                            why, (exit_code << 8) | 0x7f,
1203                                            infop, ru);
1204         }
1205
1206         write_lock_irq(&tasklist_lock);
1207
1208         /*
1209          * This uses xchg to be atomic with the thread resuming and setting
1210          * it.  It must also be done with the write lock held to prevent a
1211          * race with the EXIT_ZOMBIE case.
1212          */
1213         exit_code = xchg(&p->exit_code, 0);
1214         if (unlikely(p->exit_state)) {
1215                 /*
1216                  * The task resumed and then died.  Let the next iteration
1217                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1218                  * already be zero here if it resumed and did _exit(0).
1219                  * The task itself is dead and won't touch exit_code again;
1220                  * other processors in this function are locked out.
1221                  */
1222                 p->exit_code = exit_code;
1223                 exit_code = 0;
1224         }
1225         if (unlikely(exit_code == 0)) {
1226                 /*
1227                  * Another thread in this function got to it first, or it
1228                  * resumed, or it resumed and then died.
1229                  */
1230                 write_unlock_irq(&tasklist_lock);
1231 bail_ref:
1232                 put_task_struct(p);
1233                 /*
1234                  * We are returning to the wait loop without having successfully
1235                  * removed the process and having released the lock. We cannot
1236                  * continue, since the "p" task pointer is potentially stale.
1237                  *
1238                  * Return -EAGAIN, and do_wait() will restart the loop from the
1239                  * beginning. Do _not_ re-acquire the lock.
1240                  */
1241                 return -EAGAIN;
1242         }
1243
1244         /* move to end of parent's list to avoid starvation */
1245         remove_parent(p);
1246         add_parent(p, p->parent);
1247
1248         write_unlock_irq(&tasklist_lock);
1249
1250         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1251         if (!retval && stat_addr)
1252                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1253         if (!retval && infop)
1254                 retval = put_user(SIGCHLD, &infop->si_signo);
1255         if (!retval && infop)
1256                 retval = put_user(0, &infop->si_errno);
1257         if (!retval && infop)
1258                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1259                                           ? CLD_TRAPPED : CLD_STOPPED),
1260                                   &infop->si_code);
1261         if (!retval && infop)
1262                 retval = put_user(exit_code, &infop->si_status);
1263         if (!retval && infop)
1264                 retval = put_user(p->pid, &infop->si_pid);
1265         if (!retval && infop)
1266                 retval = put_user(p->uid, &infop->si_uid);
1267         if (!retval)
1268                 retval = p->pid;
1269         put_task_struct(p);
1270
1271         BUG_ON(!retval);
1272         return retval;
1273 }
1274
1275 /*
1276  * Handle do_wait work for one task in a live, non-stopped state.
1277  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1278  * the lock and this task is uninteresting.  If we return nonzero, we have
1279  * released the lock and the system call should return.
1280  */
1281 static int wait_task_continued(task_t *p, int noreap,
1282                                struct siginfo __user *infop,
1283                                int __user *stat_addr, struct rusage __user *ru)
1284 {
1285         int retval;
1286         pid_t pid;
1287         uid_t uid;
1288
1289         if (unlikely(!p->signal))
1290                 return 0;
1291
1292         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1293                 return 0;
1294
1295         spin_lock_irq(&p->sighand->siglock);
1296         /* Re-check with the lock held.  */
1297         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1298                 spin_unlock_irq(&p->sighand->siglock);
1299                 return 0;
1300         }
1301         if (!noreap)
1302                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1303         spin_unlock_irq(&p->sighand->siglock);
1304
1305         pid = p->pid;
1306         uid = p->uid;
1307         get_task_struct(p);
1308         read_unlock(&tasklist_lock);
1309
1310         if (!infop) {
1311                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1312                 put_task_struct(p);
1313                 if (!retval && stat_addr)
1314                         retval = put_user(0xffff, stat_addr);
1315                 if (!retval)
1316                         retval = p->pid;
1317         } else {
1318                 retval = wait_noreap_copyout(p, pid, uid,
1319                                              CLD_CONTINUED, SIGCONT,
1320                                              infop, ru);
1321                 BUG_ON(retval == 0);
1322         }
1323
1324         return retval;
1325 }
1326
1327
1328 static inline int my_ptrace_child(struct task_struct *p)
1329 {
1330         if (!(p->ptrace & PT_PTRACED))
1331                 return 0;
1332         if (!(p->ptrace & PT_ATTACHED))
1333                 return 1;
1334         /*
1335          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1336          * we are the attacher.  If we are the real parent, this is a race
1337          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1338          * which we have to switch the parent links, but has already set
1339          * the flags in p->ptrace.
1340          */
1341         return (p->parent != p->real_parent);
1342 }
1343
1344 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1345                     int __user *stat_addr, struct rusage __user *ru)
1346 {
1347         DECLARE_WAITQUEUE(wait, current);
1348         struct task_struct *tsk;
1349         int flag, retval;
1350
1351         add_wait_queue(&current->signal->wait_chldexit,&wait);
1352 repeat:
1353         /*
1354          * We will set this flag if we see any child that might later
1355          * match our criteria, even if we are not able to reap it yet.
1356          */
1357         flag = 0;
1358         current->state = TASK_INTERRUPTIBLE;
1359         read_lock(&tasklist_lock);
1360         tsk = current;
1361         do {
1362                 struct task_struct *p;
1363                 struct list_head *_p;
1364                 int ret;
1365
1366                 list_for_each(_p,&tsk->children) {
1367                         p = list_entry(_p,struct task_struct,sibling);
1368
1369                         ret = eligible_child(pid, options, p);
1370                         if (!ret)
1371                                 continue;
1372
1373                         switch (p->state) {
1374                         case TASK_TRACED:
1375                                 if (!my_ptrace_child(p))
1376                                         continue;
1377                                 /*FALLTHROUGH*/
1378                         case TASK_STOPPED:
1379                                 /*
1380                                  * It's stopped now, so it might later
1381                                  * continue, exit, or stop again.
1382                                  */
1383                                 flag = 1;
1384                                 if (!(options & WUNTRACED) &&
1385                                     !my_ptrace_child(p))
1386                                         continue;
1387                                 retval = wait_task_stopped(p, ret == 2,
1388                                                            (options & WNOWAIT),
1389                                                            infop,
1390                                                            stat_addr, ru);
1391                                 if (retval == -EAGAIN)
1392                                         goto repeat;
1393                                 if (retval != 0) /* He released the lock.  */
1394                                         goto end;
1395                                 break;
1396                         default:
1397                         // case EXIT_DEAD:
1398                                 if (p->exit_state == EXIT_DEAD)
1399                                         continue;
1400                         // case EXIT_ZOMBIE:
1401                                 if (p->exit_state == EXIT_ZOMBIE) {
1402                                         /*
1403                                          * Eligible but we cannot release
1404                                          * it yet:
1405                                          */
1406                                         if (ret == 2)
1407                                                 goto check_continued;
1408                                         if (!likely(options & WEXITED))
1409                                                 continue;
1410                                         retval = wait_task_zombie(
1411                                                 p, (options & WNOWAIT),
1412                                                 infop, stat_addr, ru);
1413                                         /* He released the lock.  */
1414                                         if (retval != 0)
1415                                                 goto end;
1416                                         break;
1417                                 }
1418 check_continued:
1419                                 /*
1420                                  * It's running now, so it might later
1421                                  * exit, stop, or stop and then continue.
1422                                  */
1423                                 flag = 1;
1424                                 if (!unlikely(options & WCONTINUED))
1425                                         continue;
1426                                 retval = wait_task_continued(
1427                                         p, (options & WNOWAIT),
1428                                         infop, stat_addr, ru);
1429                                 if (retval != 0) /* He released the lock.  */
1430                                         goto end;
1431                                 break;
1432                         }
1433                 }
1434                 if (!flag) {
1435                         list_for_each(_p, &tsk->ptrace_children) {
1436                                 p = list_entry(_p, struct task_struct,
1437                                                 ptrace_list);
1438                                 if (!eligible_child(pid, options, p))
1439                                         continue;
1440                                 flag = 1;
1441                                 break;
1442                         }
1443                 }
1444                 if (options & __WNOTHREAD)
1445                         break;
1446                 tsk = next_thread(tsk);
1447                 if (tsk->signal != current->signal)
1448                         BUG();
1449         } while (tsk != current);
1450
1451         read_unlock(&tasklist_lock);
1452         if (flag) {
1453                 retval = 0;
1454                 if (options & WNOHANG)
1455                         goto end;
1456                 retval = -ERESTARTSYS;
1457                 if (signal_pending(current))
1458                         goto end;
1459                 schedule();
1460                 goto repeat;
1461         }
1462         retval = -ECHILD;
1463 end:
1464         current->state = TASK_RUNNING;
1465         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1466         if (infop) {
1467                 if (retval > 0)
1468                 retval = 0;
1469                 else {
1470                         /*
1471                          * For a WNOHANG return, clear out all the fields
1472                          * we would set so the user can easily tell the
1473                          * difference.
1474                          */
1475                         if (!retval)
1476                                 retval = put_user(0, &infop->si_signo);
1477                         if (!retval)
1478                                 retval = put_user(0, &infop->si_errno);
1479                         if (!retval)
1480                                 retval = put_user(0, &infop->si_code);
1481                         if (!retval)
1482                                 retval = put_user(0, &infop->si_pid);
1483                         if (!retval)
1484                                 retval = put_user(0, &infop->si_uid);
1485                         if (!retval)
1486                                 retval = put_user(0, &infop->si_status);
1487                 }
1488         }
1489         return retval;
1490 }
1491
1492 asmlinkage long sys_waitid(int which, pid_t pid,
1493                            struct siginfo __user *infop, int options,
1494                            struct rusage __user *ru)
1495 {
1496         long ret;
1497
1498         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1499                 return -EINVAL;
1500         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1501                 return -EINVAL;
1502
1503         switch (which) {
1504         case P_ALL:
1505                 pid = -1;
1506                 break;
1507         case P_PID:
1508                 if (pid <= 0)
1509                         return -EINVAL;
1510                 break;
1511         case P_PGID:
1512                 if (pid <= 0)
1513                         return -EINVAL;
1514                 pid = -pid;
1515                 break;
1516         default:
1517                 return -EINVAL;
1518         }
1519
1520         ret = do_wait(pid, options, infop, NULL, ru);
1521
1522         /* avoid REGPARM breakage on x86: */
1523         prevent_tail_call(ret);
1524         return ret;
1525 }
1526
1527 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1528                           int options, struct rusage __user *ru)
1529 {
1530         long ret;
1531
1532         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1533                         __WNOTHREAD|__WCLONE|__WALL))
1534                 return -EINVAL;
1535         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1536
1537         /* avoid REGPARM breakage on x86: */
1538         prevent_tail_call(ret);
1539         return ret;
1540 }
1541
1542 #ifdef __ARCH_WANT_SYS_WAITPID
1543
1544 /*
1545  * sys_waitpid() remains for compatibility. waitpid() should be
1546  * implemented by calling sys_wait4() from libc.a.
1547  */
1548 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1549 {
1550         return sys_wait4(pid, stat_addr, options, NULL);
1551 }
1552
1553 #endif