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