[PATCH] rcu: add rcu_sync torture type to rcutorture
[linux-2.6.git] / kernel / exit.c
1 /*
2  *  linux/kernel/exit.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6
7 #include <linux/mm.h>
8 #include <linux/slab.h>
9 #include <linux/interrupt.h>
10 #include <linux/smp_lock.h>
11 #include <linux/module.h>
12 #include <linux/capability.h>
13 #include <linux/completion.h>
14 #include <linux/personality.h>
15 #include <linux/tty.h>
16 #include <linux/namespace.h>
17 #include <linux/key.h>
18 #include <linux/security.h>
19 #include <linux/cpu.h>
20 #include <linux/acct.h>
21 #include <linux/tsacct_kern.h>
22 #include <linux/file.h>
23 #include <linux/binfmts.h>
24 #include <linux/nsproxy.h>
25 #include <linux/ptrace.h>
26 #include <linux/profile.h>
27 #include <linux/mount.h>
28 #include <linux/proc_fs.h>
29 #include <linux/mempolicy.h>
30 #include <linux/taskstats_kern.h>
31 #include <linux/delayacct.h>
32 #include <linux/cpuset.h>
33 #include <linux/syscalls.h>
34 #include <linux/signal.h>
35 #include <linux/posix-timers.h>
36 #include <linux/cn_proc.h>
37 #include <linux/mutex.h>
38 #include <linux/futex.h>
39 #include <linux/compat.h>
40 #include <linux/pipe_fs_i.h>
41 #include <linux/audit.h> /* for audit_free() */
42 #include <linux/resource.h>
43 #include <linux/blkdev.h>
44
45 #include <asm/uaccess.h>
46 #include <asm/unistd.h>
47 #include <asm/pgtable.h>
48 #include <asm/mmu_context.h>
49
50 extern void sem_exit (void);
51 extern struct task_struct *child_reaper;
52
53 static void exit_mm(struct task_struct * tsk);
54
55 static void __unhash_process(struct task_struct *p)
56 {
57         nr_threads--;
58         detach_pid(p, PIDTYPE_PID);
59         if (thread_group_leader(p)) {
60                 detach_pid(p, PIDTYPE_PGID);
61                 detach_pid(p, PIDTYPE_SID);
62
63                 list_del_rcu(&p->tasks);
64                 __get_cpu_var(process_counts)--;
65         }
66         list_del_rcu(&p->thread_group);
67         remove_parent(p);
68 }
69
70 /*
71  * This function expects the tasklist_lock write-locked.
72  */
73 static void __exit_signal(struct task_struct *tsk)
74 {
75         struct signal_struct *sig = tsk->signal;
76         struct sighand_struct *sighand;
77
78         BUG_ON(!sig);
79         BUG_ON(!atomic_read(&sig->count));
80
81         rcu_read_lock();
82         sighand = rcu_dereference(tsk->sighand);
83         spin_lock(&sighand->siglock);
84
85         posix_cpu_timers_exit(tsk);
86         if (atomic_dec_and_test(&sig->count))
87                 posix_cpu_timers_exit_group(tsk);
88         else {
89                 /*
90                  * If there is any task waiting for the group exit
91                  * then notify it:
92                  */
93                 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
94                         wake_up_process(sig->group_exit_task);
95                         sig->group_exit_task = NULL;
96                 }
97                 if (tsk == sig->curr_target)
98                         sig->curr_target = next_thread(tsk);
99                 /*
100                  * Accumulate here the counters for all threads but the
101                  * group leader as they die, so they can be added into
102                  * the process-wide totals when those are taken.
103                  * The group leader stays around as a zombie as long
104                  * as there are other threads.  When it gets reaped,
105                  * the exit.c code will add its counts into these totals.
106                  * We won't ever get here for the group leader, since it
107                  * will have been the last reference on the signal_struct.
108                  */
109                 sig->utime = cputime_add(sig->utime, tsk->utime);
110                 sig->stime = cputime_add(sig->stime, tsk->stime);
111                 sig->min_flt += tsk->min_flt;
112                 sig->maj_flt += tsk->maj_flt;
113                 sig->nvcsw += tsk->nvcsw;
114                 sig->nivcsw += tsk->nivcsw;
115                 sig->sched_time += tsk->sched_time;
116                 sig = NULL; /* Marker for below. */
117         }
118
119         __unhash_process(tsk);
120
121         tsk->signal = NULL;
122         tsk->sighand = NULL;
123         spin_unlock(&sighand->siglock);
124         rcu_read_unlock();
125
126         __cleanup_sighand(sighand);
127         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
128         flush_sigqueue(&tsk->pending);
129         if (sig) {
130                 flush_sigqueue(&sig->shared_pending);
131                 __cleanup_signal(sig);
132         }
133 }
134
135 static void delayed_put_task_struct(struct rcu_head *rhp)
136 {
137         put_task_struct(container_of(rhp, struct task_struct, rcu));
138 }
139
140 void release_task(struct task_struct * p)
141 {
142         struct task_struct *leader;
143         int zap_leader;
144 repeat:
145         atomic_dec(&p->user->processes);
146         write_lock_irq(&tasklist_lock);
147         ptrace_unlink(p);
148         BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
149         __exit_signal(p);
150
151         /*
152          * If we are the last non-leader member of the thread
153          * group, and the leader is zombie, then notify the
154          * group leader's parent process. (if it wants notification.)
155          */
156         zap_leader = 0;
157         leader = p->group_leader;
158         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
159                 BUG_ON(leader->exit_signal == -1);
160                 do_notify_parent(leader, leader->exit_signal);
161                 /*
162                  * If we were the last child thread and the leader has
163                  * exited already, and the leader's parent ignores SIGCHLD,
164                  * then we are the one who should release the leader.
165                  *
166                  * do_notify_parent() will have marked it self-reaping in
167                  * that case.
168                  */
169                 zap_leader = (leader->exit_signal == -1);
170         }
171
172         sched_exit(p);
173         write_unlock_irq(&tasklist_lock);
174         proc_flush_task(p);
175         release_thread(p);
176         call_rcu(&p->rcu, delayed_put_task_struct);
177
178         p = leader;
179         if (unlikely(zap_leader))
180                 goto repeat;
181 }
182
183 /*
184  * This checks not only the pgrp, but falls back on the pid if no
185  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
186  * without this...
187  */
188 int session_of_pgrp(int pgrp)
189 {
190         struct task_struct *p;
191         int sid = -1;
192
193         read_lock(&tasklist_lock);
194         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
195                 if (p->signal->session > 0) {
196                         sid = p->signal->session;
197                         goto out;
198                 }
199         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
200         p = find_task_by_pid(pgrp);
201         if (p)
202                 sid = p->signal->session;
203 out:
204         read_unlock(&tasklist_lock);
205         
206         return sid;
207 }
208
209 /*
210  * Determine if a process group is "orphaned", according to the POSIX
211  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
212  * by terminal-generated stop signals.  Newly orphaned process groups are
213  * to receive a SIGHUP and a SIGCONT.
214  *
215  * "I ask you, have you ever known what it is to be an orphan?"
216  */
217 static int will_become_orphaned_pgrp(int pgrp, struct task_struct *ignored_task)
218 {
219         struct task_struct *p;
220         int ret = 1;
221
222         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
223                 if (p == ignored_task
224                                 || p->exit_state
225                                 || is_init(p->real_parent))
226                         continue;
227                 if (process_group(p->real_parent) != pgrp
228                             && p->real_parent->signal->session == p->signal->session) {
229                         ret = 0;
230                         break;
231                 }
232         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
233         return ret;     /* (sighing) "Often!" */
234 }
235
236 int is_orphaned_pgrp(int pgrp)
237 {
238         int retval;
239
240         read_lock(&tasklist_lock);
241         retval = will_become_orphaned_pgrp(pgrp, NULL);
242         read_unlock(&tasklist_lock);
243
244         return retval;
245 }
246
247 static int has_stopped_jobs(int pgrp)
248 {
249         int retval = 0;
250         struct task_struct *p;
251
252         do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
253                 if (p->state != TASK_STOPPED)
254                         continue;
255                 retval = 1;
256                 break;
257         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
258         return retval;
259 }
260
261 /**
262  * reparent_to_init - Reparent the calling kernel thread to the init task.
263  *
264  * If a kernel thread is launched as a result of a system call, or if
265  * it ever exits, it should generally reparent itself to init so that
266  * it is correctly cleaned up on exit.
267  *
268  * The various task state such as scheduling policy and priority may have
269  * been inherited from a user process, so we reset them to sane values here.
270  *
271  * NOTE that reparent_to_init() gives the caller full capabilities.
272  */
273 static void reparent_to_init(void)
274 {
275         write_lock_irq(&tasklist_lock);
276
277         ptrace_unlink(current);
278         /* Reparent to init */
279         remove_parent(current);
280         current->parent = child_reaper;
281         current->real_parent = child_reaper;
282         add_parent(current);
283
284         /* Set the exit signal to SIGCHLD so we signal init on exit */
285         current->exit_signal = SIGCHLD;
286
287         if (!has_rt_policy(current) && (task_nice(current) < 0))
288                 set_user_nice(current, 0);
289         /* cpus_allowed? */
290         /* rt_priority? */
291         /* signals? */
292         security_task_reparent_to_init(current);
293         memcpy(current->signal->rlim, init_task.signal->rlim,
294                sizeof(current->signal->rlim));
295         atomic_inc(&(INIT_USER->__count));
296         write_unlock_irq(&tasklist_lock);
297         switch_uid(INIT_USER);
298 }
299
300 void __set_special_pids(pid_t session, pid_t pgrp)
301 {
302         struct task_struct *curr = current->group_leader;
303
304         if (curr->signal->session != session) {
305                 detach_pid(curr, PIDTYPE_SID);
306                 curr->signal->session = session;
307                 attach_pid(curr, PIDTYPE_SID, session);
308         }
309         if (process_group(curr) != pgrp) {
310                 detach_pid(curr, PIDTYPE_PGID);
311                 curr->signal->pgrp = pgrp;
312                 attach_pid(curr, PIDTYPE_PGID, pgrp);
313         }
314 }
315
316 void set_special_pids(pid_t session, pid_t pgrp)
317 {
318         write_lock_irq(&tasklist_lock);
319         __set_special_pids(session, pgrp);
320         write_unlock_irq(&tasklist_lock);
321 }
322
323 /*
324  * Let kernel threads use this to say that they
325  * allow a certain signal (since daemonize() will
326  * have disabled all of them by default).
327  */
328 int allow_signal(int sig)
329 {
330         if (!valid_signal(sig) || sig < 1)
331                 return -EINVAL;
332
333         spin_lock_irq(&current->sighand->siglock);
334         sigdelset(&current->blocked, sig);
335         if (!current->mm) {
336                 /* Kernel threads handle their own signals.
337                    Let the signal code know it'll be handled, so
338                    that they don't get converted to SIGKILL or
339                    just silently dropped */
340                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
341         }
342         recalc_sigpending();
343         spin_unlock_irq(&current->sighand->siglock);
344         return 0;
345 }
346
347 EXPORT_SYMBOL(allow_signal);
348
349 int disallow_signal(int sig)
350 {
351         if (!valid_signal(sig) || sig < 1)
352                 return -EINVAL;
353
354         spin_lock_irq(&current->sighand->siglock);
355         sigaddset(&current->blocked, sig);
356         recalc_sigpending();
357         spin_unlock_irq(&current->sighand->siglock);
358         return 0;
359 }
360
361 EXPORT_SYMBOL(disallow_signal);
362
363 /*
364  *      Put all the gunge required to become a kernel thread without
365  *      attached user resources in one place where it belongs.
366  */
367
368 void daemonize(const char *name, ...)
369 {
370         va_list args;
371         struct fs_struct *fs;
372         sigset_t blocked;
373
374         va_start(args, name);
375         vsnprintf(current->comm, sizeof(current->comm), name, args);
376         va_end(args);
377
378         /*
379          * If we were started as result of loading a module, close all of the
380          * user space pages.  We don't need them, and if we didn't close them
381          * they would be locked into memory.
382          */
383         exit_mm(current);
384
385         set_special_pids(1, 1);
386         mutex_lock(&tty_mutex);
387         current->signal->tty = NULL;
388         mutex_unlock(&tty_mutex);
389
390         /* Block and flush all signals */
391         sigfillset(&blocked);
392         sigprocmask(SIG_BLOCK, &blocked, NULL);
393         flush_signals(current);
394
395         /* Become as one with the init task */
396
397         exit_fs(current);       /* current->fs->count--; */
398         fs = init_task.fs;
399         current->fs = fs;
400         atomic_inc(&fs->count);
401
402         exit_task_namespaces(current);
403         current->nsproxy = init_task.nsproxy;
404         get_task_namespaces(current);
405
406         exit_files(current);
407         current->files = init_task.files;
408         atomic_inc(&current->files->count);
409
410         reparent_to_init();
411 }
412
413 EXPORT_SYMBOL(daemonize);
414
415 static void close_files(struct files_struct * files)
416 {
417         int i, j;
418         struct fdtable *fdt;
419
420         j = 0;
421
422         /*
423          * It is safe to dereference the fd table without RCU or
424          * ->file_lock because this is the last reference to the
425          * files structure.
426          */
427         fdt = files_fdtable(files);
428         for (;;) {
429                 unsigned long set;
430                 i = j * __NFDBITS;
431                 if (i >= fdt->max_fdset || i >= fdt->max_fds)
432                         break;
433                 set = fdt->open_fds->fds_bits[j++];
434                 while (set) {
435                         if (set & 1) {
436                                 struct file * file = xchg(&fdt->fd[i], NULL);
437                                 if (file)
438                                         filp_close(file, files);
439                         }
440                         i++;
441                         set >>= 1;
442                 }
443         }
444 }
445
446 struct files_struct *get_files_struct(struct task_struct *task)
447 {
448         struct files_struct *files;
449
450         task_lock(task);
451         files = task->files;
452         if (files)
453                 atomic_inc(&files->count);
454         task_unlock(task);
455
456         return files;
457 }
458
459 void fastcall put_files_struct(struct files_struct *files)
460 {
461         struct fdtable *fdt;
462
463         if (atomic_dec_and_test(&files->count)) {
464                 close_files(files);
465                 /*
466                  * Free the fd and fdset arrays if we expanded them.
467                  * If the fdtable was embedded, pass files for freeing
468                  * at the end of the RCU grace period. Otherwise,
469                  * you can free files immediately.
470                  */
471                 fdt = files_fdtable(files);
472                 if (fdt == &files->fdtab)
473                         fdt->free_files = files;
474                 else
475                         kmem_cache_free(files_cachep, files);
476                 free_fdtable(fdt);
477         }
478 }
479
480 EXPORT_SYMBOL(put_files_struct);
481
482 void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
483 {
484         struct files_struct *old;
485
486         old = tsk->files;
487         task_lock(tsk);
488         tsk->files = files;
489         task_unlock(tsk);
490         put_files_struct(old);
491 }
492 EXPORT_SYMBOL(reset_files_struct);
493
494 static inline void __exit_files(struct task_struct *tsk)
495 {
496         struct files_struct * files = tsk->files;
497
498         if (files) {
499                 task_lock(tsk);
500                 tsk->files = NULL;
501                 task_unlock(tsk);
502                 put_files_struct(files);
503         }
504 }
505
506 void exit_files(struct task_struct *tsk)
507 {
508         __exit_files(tsk);
509 }
510
511 static inline void __put_fs_struct(struct fs_struct *fs)
512 {
513         /* No need to hold fs->lock if we are killing it */
514         if (atomic_dec_and_test(&fs->count)) {
515                 dput(fs->root);
516                 mntput(fs->rootmnt);
517                 dput(fs->pwd);
518                 mntput(fs->pwdmnt);
519                 if (fs->altroot) {
520                         dput(fs->altroot);
521                         mntput(fs->altrootmnt);
522                 }
523                 kmem_cache_free(fs_cachep, fs);
524         }
525 }
526
527 void put_fs_struct(struct fs_struct *fs)
528 {
529         __put_fs_struct(fs);
530 }
531
532 static inline void __exit_fs(struct task_struct *tsk)
533 {
534         struct fs_struct * fs = tsk->fs;
535
536         if (fs) {
537                 task_lock(tsk);
538                 tsk->fs = NULL;
539                 task_unlock(tsk);
540                 __put_fs_struct(fs);
541         }
542 }
543
544 void exit_fs(struct task_struct *tsk)
545 {
546         __exit_fs(tsk);
547 }
548
549 EXPORT_SYMBOL_GPL(exit_fs);
550
551 /*
552  * Turn us into a lazy TLB process if we
553  * aren't already..
554  */
555 static void exit_mm(struct task_struct * tsk)
556 {
557         struct mm_struct *mm = tsk->mm;
558
559         mm_release(tsk, mm);
560         if (!mm)
561                 return;
562         /*
563          * Serialize with any possible pending coredump.
564          * We must hold mmap_sem around checking core_waiters
565          * and clearing tsk->mm.  The core-inducing thread
566          * will increment core_waiters for each thread in the
567          * group with ->mm != NULL.
568          */
569         down_read(&mm->mmap_sem);
570         if (mm->core_waiters) {
571                 up_read(&mm->mmap_sem);
572                 down_write(&mm->mmap_sem);
573                 if (!--mm->core_waiters)
574                         complete(mm->core_startup_done);
575                 up_write(&mm->mmap_sem);
576
577                 wait_for_completion(&mm->core_done);
578                 down_read(&mm->mmap_sem);
579         }
580         atomic_inc(&mm->mm_count);
581         BUG_ON(mm != tsk->active_mm);
582         /* more a memory barrier than a real lock */
583         task_lock(tsk);
584         tsk->mm = NULL;
585         up_read(&mm->mmap_sem);
586         enter_lazy_tlb(mm, current);
587         task_unlock(tsk);
588         mmput(mm);
589 }
590
591 static inline void
592 choose_new_parent(struct task_struct *p, struct task_struct *reaper)
593 {
594         /*
595          * Make sure we're not reparenting to ourselves and that
596          * the parent is not a zombie.
597          */
598         BUG_ON(p == reaper || reaper->exit_state);
599         p->real_parent = reaper;
600 }
601
602 static void
603 reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
604 {
605         /* We don't want people slaying init.  */
606         if (p->exit_signal != -1)
607                 p->exit_signal = SIGCHLD;
608
609         if (p->pdeath_signal)
610                 /* We already hold the tasklist_lock here.  */
611                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
612
613         /* Move the child from its dying parent to the new one.  */
614         if (unlikely(traced)) {
615                 /* Preserve ptrace links if someone else is tracing this child.  */
616                 list_del_init(&p->ptrace_list);
617                 if (p->parent != p->real_parent)
618                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
619         } else {
620                 /* If this child is being traced, then we're the one tracing it
621                  * anyway, so let go of it.
622                  */
623                 p->ptrace = 0;
624                 remove_parent(p);
625                 p->parent = p->real_parent;
626                 add_parent(p);
627
628                 /* If we'd notified the old parent about this child's death,
629                  * also notify the new parent.
630                  */
631                 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
632                     thread_group_empty(p))
633                         do_notify_parent(p, p->exit_signal);
634                 else if (p->state == TASK_TRACED) {
635                         /*
636                          * If it was at a trace stop, turn it into
637                          * a normal stop since it's no longer being
638                          * traced.
639                          */
640                         ptrace_untrace(p);
641                 }
642         }
643
644         /*
645          * process group orphan check
646          * Case ii: Our child is in a different pgrp
647          * than we are, and it was the only connection
648          * outside, so the child pgrp is now orphaned.
649          */
650         if ((process_group(p) != process_group(father)) &&
651             (p->signal->session == father->signal->session)) {
652                 int pgrp = process_group(p);
653
654                 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
655                         __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
656                         __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
657                 }
658         }
659 }
660
661 /*
662  * When we die, we re-parent all our children.
663  * Try to give them to another thread in our thread
664  * group, and if no such member exists, give it to
665  * the global child reaper process (ie "init")
666  */
667 static void
668 forget_original_parent(struct task_struct *father, struct list_head *to_release)
669 {
670         struct task_struct *p, *reaper = father;
671         struct list_head *_p, *_n;
672
673         do {
674                 reaper = next_thread(reaper);
675                 if (reaper == father) {
676                         reaper = child_reaper;
677                         break;
678                 }
679         } while (reaper->exit_state);
680
681         /*
682          * There are only two places where our children can be:
683          *
684          * - in our child list
685          * - in our ptraced child list
686          *
687          * Search them and reparent children.
688          */
689         list_for_each_safe(_p, _n, &father->children) {
690                 int ptrace;
691                 p = list_entry(_p, struct task_struct, sibling);
692
693                 ptrace = p->ptrace;
694
695                 /* if father isn't the real parent, then ptrace must be enabled */
696                 BUG_ON(father != p->real_parent && !ptrace);
697
698                 if (father == p->real_parent) {
699                         /* reparent with a reaper, real father it's us */
700                         choose_new_parent(p, reaper);
701                         reparent_thread(p, father, 0);
702                 } else {
703                         /* reparent ptraced task to its real parent */
704                         __ptrace_unlink (p);
705                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
706                             thread_group_empty(p))
707                                 do_notify_parent(p, p->exit_signal);
708                 }
709
710                 /*
711                  * if the ptraced child is a zombie with exit_signal == -1
712                  * we must collect it before we exit, or it will remain
713                  * zombie forever since we prevented it from self-reap itself
714                  * while it was being traced by us, to be able to see it in wait4.
715                  */
716                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
717                         list_add(&p->ptrace_list, to_release);
718         }
719         list_for_each_safe(_p, _n, &father->ptrace_children) {
720                 p = list_entry(_p, struct task_struct, ptrace_list);
721                 choose_new_parent(p, reaper);
722                 reparent_thread(p, father, 1);
723         }
724 }
725
726 /*
727  * Send signals to all our closest relatives so that they know
728  * to properly mourn us..
729  */
730 static void exit_notify(struct task_struct *tsk)
731 {
732         int state;
733         struct task_struct *t;
734         struct list_head ptrace_dead, *_p, *_n;
735
736         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
737             && !thread_group_empty(tsk)) {
738                 /*
739                  * This occurs when there was a race between our exit
740                  * syscall and a group signal choosing us as the one to
741                  * wake up.  It could be that we are the only thread
742                  * alerted to check for pending signals, but another thread
743                  * should be woken now to take the signal since we will not.
744                  * Now we'll wake all the threads in the group just to make
745                  * sure someone gets all the pending signals.
746                  */
747                 read_lock(&tasklist_lock);
748                 spin_lock_irq(&tsk->sighand->siglock);
749                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
750                         if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
751                                 recalc_sigpending_tsk(t);
752                                 if (signal_pending(t))
753                                         signal_wake_up(t, 0);
754                         }
755                 spin_unlock_irq(&tsk->sighand->siglock);
756                 read_unlock(&tasklist_lock);
757         }
758
759         write_lock_irq(&tasklist_lock);
760
761         /*
762          * This does two things:
763          *
764          * A.  Make init inherit all the child processes
765          * B.  Check to see if any process groups have become orphaned
766          *      as a result of our exiting, and if they have any stopped
767          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
768          */
769
770         INIT_LIST_HEAD(&ptrace_dead);
771         forget_original_parent(tsk, &ptrace_dead);
772         BUG_ON(!list_empty(&tsk->children));
773         BUG_ON(!list_empty(&tsk->ptrace_children));
774
775         /*
776          * Check to see if any process groups have become orphaned
777          * as a result of our exiting, and if they have any stopped
778          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
779          *
780          * Case i: Our father is in a different pgrp than we are
781          * and we were the only connection outside, so our pgrp
782          * is about to become orphaned.
783          */
784          
785         t = tsk->real_parent;
786         
787         if ((process_group(t) != process_group(tsk)) &&
788             (t->signal->session == tsk->signal->session) &&
789             will_become_orphaned_pgrp(process_group(tsk), tsk) &&
790             has_stopped_jobs(process_group(tsk))) {
791                 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
792                 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
793         }
794
795         /* Let father know we died 
796          *
797          * Thread signals are configurable, but you aren't going to use
798          * that to send signals to arbitary processes. 
799          * That stops right now.
800          *
801          * If the parent exec id doesn't match the exec id we saved
802          * when we started then we know the parent has changed security
803          * domain.
804          *
805          * If our self_exec id doesn't match our parent_exec_id then
806          * we have changed execution domain as these two values started
807          * the same after a fork.
808          *      
809          */
810         
811         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
812             ( tsk->parent_exec_id != t->self_exec_id  ||
813               tsk->self_exec_id != tsk->parent_exec_id)
814             && !capable(CAP_KILL))
815                 tsk->exit_signal = SIGCHLD;
816
817
818         /* If something other than our normal parent is ptracing us, then
819          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
820          * only has special meaning to our real parent.
821          */
822         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
823                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
824                 do_notify_parent(tsk, signal);
825         } else if (tsk->ptrace) {
826                 do_notify_parent(tsk, SIGCHLD);
827         }
828
829         state = EXIT_ZOMBIE;
830         if (tsk->exit_signal == -1 &&
831             (likely(tsk->ptrace == 0) ||
832              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
833                 state = EXIT_DEAD;
834         tsk->exit_state = state;
835
836         write_unlock_irq(&tasklist_lock);
837
838         list_for_each_safe(_p, _n, &ptrace_dead) {
839                 list_del_init(_p);
840                 t = list_entry(_p, struct task_struct, ptrace_list);
841                 release_task(t);
842         }
843
844         /* If the process is dead, release it - nobody will wait for it */
845         if (state == EXIT_DEAD)
846                 release_task(tsk);
847 }
848
849 fastcall NORET_TYPE void do_exit(long code)
850 {
851         struct task_struct *tsk = current;
852         struct taskstats *tidstats;
853         int group_dead;
854         unsigned int mycpu;
855
856         profile_task_exit(tsk);
857
858         WARN_ON(atomic_read(&tsk->fs_excl));
859
860         if (unlikely(in_interrupt()))
861                 panic("Aiee, killing interrupt handler!");
862         if (unlikely(!tsk->pid))
863                 panic("Attempted to kill the idle task!");
864         if (unlikely(tsk == child_reaper))
865                 panic("Attempted to kill init!");
866
867         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
868                 current->ptrace_message = code;
869                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
870         }
871
872         /*
873          * We're taking recursive faults here in do_exit. Safest is to just
874          * leave this task alone and wait for reboot.
875          */
876         if (unlikely(tsk->flags & PF_EXITING)) {
877                 printk(KERN_ALERT
878                         "Fixing recursive fault but reboot is needed!\n");
879                 if (tsk->io_context)
880                         exit_io_context();
881                 set_current_state(TASK_UNINTERRUPTIBLE);
882                 schedule();
883         }
884
885         tsk->flags |= PF_EXITING;
886
887         if (unlikely(in_atomic()))
888                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
889                                 current->comm, current->pid,
890                                 preempt_count());
891
892         taskstats_exit_alloc(&tidstats, &mycpu);
893
894         acct_update_integrals(tsk);
895         if (tsk->mm) {
896                 update_hiwater_rss(tsk->mm);
897                 update_hiwater_vm(tsk->mm);
898         }
899         group_dead = atomic_dec_and_test(&tsk->signal->live);
900         if (group_dead) {
901                 hrtimer_cancel(&tsk->signal->real_timer);
902                 exit_itimers(tsk->signal);
903         }
904         acct_collect(code, group_dead);
905         if (unlikely(tsk->robust_list))
906                 exit_robust_list(tsk);
907 #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
908         if (unlikely(tsk->compat_robust_list))
909                 compat_exit_robust_list(tsk);
910 #endif
911         if (unlikely(tsk->audit_context))
912                 audit_free(tsk);
913         taskstats_exit_send(tsk, tidstats, group_dead, mycpu);
914         taskstats_exit_free(tidstats);
915
916         exit_mm(tsk);
917
918         if (group_dead)
919                 acct_process();
920         exit_sem(tsk);
921         __exit_files(tsk);
922         __exit_fs(tsk);
923         exit_thread();
924         cpuset_exit(tsk);
925         exit_keys(tsk);
926
927         if (group_dead && tsk->signal->leader)
928                 disassociate_ctty(1);
929
930         module_put(task_thread_info(tsk)->exec_domain->module);
931         if (tsk->binfmt)
932                 module_put(tsk->binfmt->module);
933
934         tsk->exit_code = code;
935         proc_exit_connector(tsk);
936         exit_notify(tsk);
937         exit_task_namespaces(tsk);
938 #ifdef CONFIG_NUMA
939         mpol_free(tsk->mempolicy);
940         tsk->mempolicy = NULL;
941 #endif
942         /*
943          * This must happen late, after the PID is not
944          * hashed anymore:
945          */
946         if (unlikely(!list_empty(&tsk->pi_state_list)))
947                 exit_pi_state_list(tsk);
948         if (unlikely(current->pi_state_cache))
949                 kfree(current->pi_state_cache);
950         /*
951          * Make sure we are holding no locks:
952          */
953         debug_check_no_locks_held(tsk);
954
955         if (tsk->io_context)
956                 exit_io_context();
957
958         if (tsk->splice_pipe)
959                 __free_pipe_info(tsk->splice_pipe);
960
961         preempt_disable();
962         /* causes final put_task_struct in finish_task_switch(). */
963         tsk->state = TASK_DEAD;
964
965         schedule();
966         BUG();
967         /* Avoid "noreturn function does return".  */
968         for (;;)
969                 cpu_relax();    /* For when BUG is null */
970 }
971
972 EXPORT_SYMBOL_GPL(do_exit);
973
974 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
975 {
976         if (comp)
977                 complete(comp);
978
979         do_exit(code);
980 }
981
982 EXPORT_SYMBOL(complete_and_exit);
983
984 asmlinkage long sys_exit(int error_code)
985 {
986         do_exit((error_code&0xff)<<8);
987 }
988
989 /*
990  * Take down every thread in the group.  This is called by fatal signals
991  * as well as by sys_exit_group (below).
992  */
993 NORET_TYPE void
994 do_group_exit(int exit_code)
995 {
996         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
997
998         if (current->signal->flags & SIGNAL_GROUP_EXIT)
999                 exit_code = current->signal->group_exit_code;
1000         else if (!thread_group_empty(current)) {
1001                 struct signal_struct *const sig = current->signal;
1002                 struct sighand_struct *const sighand = current->sighand;
1003                 spin_lock_irq(&sighand->siglock);
1004                 if (sig->flags & SIGNAL_GROUP_EXIT)
1005                         /* Another thread got here before we took the lock.  */
1006                         exit_code = sig->group_exit_code;
1007                 else {
1008                         sig->group_exit_code = exit_code;
1009                         zap_other_threads(current);
1010                 }
1011                 spin_unlock_irq(&sighand->siglock);
1012         }
1013
1014         do_exit(exit_code);
1015         /* NOTREACHED */
1016 }
1017
1018 /*
1019  * this kills every thread in the thread group. Note that any externally
1020  * wait4()-ing process will get the correct exit code - even if this
1021  * thread is not the thread group leader.
1022  */
1023 asmlinkage void sys_exit_group(int error_code)
1024 {
1025         do_group_exit((error_code & 0xff) << 8);
1026 }
1027
1028 static int eligible_child(pid_t pid, int options, struct task_struct *p)
1029 {
1030         if (pid > 0) {
1031                 if (p->pid != pid)
1032                         return 0;
1033         } else if (!pid) {
1034                 if (process_group(p) != process_group(current))
1035                         return 0;
1036         } else if (pid != -1) {
1037                 if (process_group(p) != -pid)
1038                         return 0;
1039         }
1040
1041         /*
1042          * Do not consider detached threads that are
1043          * not ptraced:
1044          */
1045         if (p->exit_signal == -1 && !p->ptrace)
1046                 return 0;
1047
1048         /* Wait for all children (clone and not) if __WALL is set;
1049          * otherwise, wait for clone children *only* if __WCLONE is
1050          * set; otherwise, wait for non-clone children *only*.  (Note:
1051          * A "clone" child here is one that reports to its parent
1052          * using a signal other than SIGCHLD.) */
1053         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1054             && !(options & __WALL))
1055                 return 0;
1056         /*
1057          * Do not consider thread group leaders that are
1058          * in a non-empty thread group:
1059          */
1060         if (delay_group_leader(p))
1061                 return 2;
1062
1063         if (security_task_wait(p))
1064                 return 0;
1065
1066         return 1;
1067 }
1068
1069 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1070                                int why, int status,
1071                                struct siginfo __user *infop,
1072                                struct rusage __user *rusagep)
1073 {
1074         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1075
1076         put_task_struct(p);
1077         if (!retval)
1078                 retval = put_user(SIGCHLD, &infop->si_signo);
1079         if (!retval)
1080                 retval = put_user(0, &infop->si_errno);
1081         if (!retval)
1082                 retval = put_user((short)why, &infop->si_code);
1083         if (!retval)
1084                 retval = put_user(pid, &infop->si_pid);
1085         if (!retval)
1086                 retval = put_user(uid, &infop->si_uid);
1087         if (!retval)
1088                 retval = put_user(status, &infop->si_status);
1089         if (!retval)
1090                 retval = pid;
1091         return retval;
1092 }
1093
1094 /*
1095  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1096  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1097  * the lock and this task is uninteresting.  If we return nonzero, we have
1098  * released the lock and the system call should return.
1099  */
1100 static int wait_task_zombie(struct task_struct *p, int noreap,
1101                             struct siginfo __user *infop,
1102                             int __user *stat_addr, struct rusage __user *ru)
1103 {
1104         unsigned long state;
1105         int retval;
1106         int status;
1107
1108         if (unlikely(noreap)) {
1109                 pid_t pid = p->pid;
1110                 uid_t uid = p->uid;
1111                 int exit_code = p->exit_code;
1112                 int why, status;
1113
1114                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1115                         return 0;
1116                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1117                         return 0;
1118                 get_task_struct(p);
1119                 read_unlock(&tasklist_lock);
1120                 if ((exit_code & 0x7f) == 0) {
1121                         why = CLD_EXITED;
1122                         status = exit_code >> 8;
1123                 } else {
1124                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1125                         status = exit_code & 0x7f;
1126                 }
1127                 return wait_noreap_copyout(p, pid, uid, why,
1128                                            status, infop, ru);
1129         }
1130
1131         /*
1132          * Try to move the task's state to DEAD
1133          * only one thread is allowed to do this:
1134          */
1135         state = xchg(&p->exit_state, EXIT_DEAD);
1136         if (state != EXIT_ZOMBIE) {
1137                 BUG_ON(state != EXIT_DEAD);
1138                 return 0;
1139         }
1140         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1141                 /*
1142                  * This can only happen in a race with a ptraced thread
1143                  * dying on another processor.
1144                  */
1145                 return 0;
1146         }
1147
1148         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1149                 struct signal_struct *psig;
1150                 struct signal_struct *sig;
1151
1152                 /*
1153                  * The resource counters for the group leader are in its
1154                  * own task_struct.  Those for dead threads in the group
1155                  * are in its signal_struct, as are those for the child
1156                  * processes it has previously reaped.  All these
1157                  * accumulate in the parent's signal_struct c* fields.
1158                  *
1159                  * We don't bother to take a lock here to protect these
1160                  * p->signal fields, because they are only touched by
1161                  * __exit_signal, which runs with tasklist_lock
1162                  * write-locked anyway, and so is excluded here.  We do
1163                  * need to protect the access to p->parent->signal fields,
1164                  * as other threads in the parent group can be right
1165                  * here reaping other children at the same time.
1166                  */
1167                 spin_lock_irq(&p->parent->sighand->siglock);
1168                 psig = p->parent->signal;
1169                 sig = p->signal;
1170                 psig->cutime =
1171                         cputime_add(psig->cutime,
1172                         cputime_add(p->utime,
1173                         cputime_add(sig->utime,
1174                                     sig->cutime)));
1175                 psig->cstime =
1176                         cputime_add(psig->cstime,
1177                         cputime_add(p->stime,
1178                         cputime_add(sig->stime,
1179                                     sig->cstime)));
1180                 psig->cmin_flt +=
1181                         p->min_flt + sig->min_flt + sig->cmin_flt;
1182                 psig->cmaj_flt +=
1183                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1184                 psig->cnvcsw +=
1185                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1186                 psig->cnivcsw +=
1187                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1188                 spin_unlock_irq(&p->parent->sighand->siglock);
1189         }
1190
1191         /*
1192          * Now we are sure this task is interesting, and no other
1193          * thread can reap it because we set its state to EXIT_DEAD.
1194          */
1195         read_unlock(&tasklist_lock);
1196
1197         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1198         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1199                 ? p->signal->group_exit_code : p->exit_code;
1200         if (!retval && stat_addr)
1201                 retval = put_user(status, stat_addr);
1202         if (!retval && infop)
1203                 retval = put_user(SIGCHLD, &infop->si_signo);
1204         if (!retval && infop)
1205                 retval = put_user(0, &infop->si_errno);
1206         if (!retval && infop) {
1207                 int why;
1208
1209                 if ((status & 0x7f) == 0) {
1210                         why = CLD_EXITED;
1211                         status >>= 8;
1212                 } else {
1213                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1214                         status &= 0x7f;
1215                 }
1216                 retval = put_user((short)why, &infop->si_code);
1217                 if (!retval)
1218                         retval = put_user(status, &infop->si_status);
1219         }
1220         if (!retval && infop)
1221                 retval = put_user(p->pid, &infop->si_pid);
1222         if (!retval && infop)
1223                 retval = put_user(p->uid, &infop->si_uid);
1224         if (retval) {
1225                 // TODO: is this safe?
1226                 p->exit_state = EXIT_ZOMBIE;
1227                 return retval;
1228         }
1229         retval = p->pid;
1230         if (p->real_parent != p->parent) {
1231                 write_lock_irq(&tasklist_lock);
1232                 /* Double-check with lock held.  */
1233                 if (p->real_parent != p->parent) {
1234                         __ptrace_unlink(p);
1235                         // TODO: is this safe?
1236                         p->exit_state = EXIT_ZOMBIE;
1237                         /*
1238                          * If this is not a detached task, notify the parent.
1239                          * If it's still not detached after that, don't release
1240                          * it now.
1241                          */
1242                         if (p->exit_signal != -1) {
1243                                 do_notify_parent(p, p->exit_signal);
1244                                 if (p->exit_signal != -1)
1245                                         p = NULL;
1246                         }
1247                 }
1248                 write_unlock_irq(&tasklist_lock);
1249         }
1250         if (p != NULL)
1251                 release_task(p);
1252         BUG_ON(!retval);
1253         return retval;
1254 }
1255
1256 /*
1257  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1258  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1259  * the lock and this task is uninteresting.  If we return nonzero, we have
1260  * released the lock and the system call should return.
1261  */
1262 static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1263                              int noreap, struct siginfo __user *infop,
1264                              int __user *stat_addr, struct rusage __user *ru)
1265 {
1266         int retval, exit_code;
1267
1268         if (!p->exit_code)
1269                 return 0;
1270         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1271             p->signal && p->signal->group_stop_count > 0)
1272                 /*
1273                  * A group stop is in progress and this is the group leader.
1274                  * We won't report until all threads have stopped.
1275                  */
1276                 return 0;
1277
1278         /*
1279          * Now we are pretty sure this task is interesting.
1280          * Make sure it doesn't get reaped out from under us while we
1281          * give up the lock and then examine it below.  We don't want to
1282          * keep holding onto the tasklist_lock while we call getrusage and
1283          * possibly take page faults for user memory.
1284          */
1285         get_task_struct(p);
1286         read_unlock(&tasklist_lock);
1287
1288         if (unlikely(noreap)) {
1289                 pid_t pid = p->pid;
1290                 uid_t uid = p->uid;
1291                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1292
1293                 exit_code = p->exit_code;
1294                 if (unlikely(!exit_code) ||
1295                     unlikely(p->state & TASK_TRACED))
1296                         goto bail_ref;
1297                 return wait_noreap_copyout(p, pid, uid,
1298                                            why, (exit_code << 8) | 0x7f,
1299                                            infop, ru);
1300         }
1301
1302         write_lock_irq(&tasklist_lock);
1303
1304         /*
1305          * This uses xchg to be atomic with the thread resuming and setting
1306          * it.  It must also be done with the write lock held to prevent a
1307          * race with the EXIT_ZOMBIE case.
1308          */
1309         exit_code = xchg(&p->exit_code, 0);
1310         if (unlikely(p->exit_state)) {
1311                 /*
1312                  * The task resumed and then died.  Let the next iteration
1313                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1314                  * already be zero here if it resumed and did _exit(0).
1315                  * The task itself is dead and won't touch exit_code again;
1316                  * other processors in this function are locked out.
1317                  */
1318                 p->exit_code = exit_code;
1319                 exit_code = 0;
1320         }
1321         if (unlikely(exit_code == 0)) {
1322                 /*
1323                  * Another thread in this function got to it first, or it
1324                  * resumed, or it resumed and then died.
1325                  */
1326                 write_unlock_irq(&tasklist_lock);
1327 bail_ref:
1328                 put_task_struct(p);
1329                 /*
1330                  * We are returning to the wait loop without having successfully
1331                  * removed the process and having released the lock. We cannot
1332                  * continue, since the "p" task pointer is potentially stale.
1333                  *
1334                  * Return -EAGAIN, and do_wait() will restart the loop from the
1335                  * beginning. Do _not_ re-acquire the lock.
1336                  */
1337                 return -EAGAIN;
1338         }
1339
1340         /* move to end of parent's list to avoid starvation */
1341         remove_parent(p);
1342         add_parent(p);
1343
1344         write_unlock_irq(&tasklist_lock);
1345
1346         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1347         if (!retval && stat_addr)
1348                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1349         if (!retval && infop)
1350                 retval = put_user(SIGCHLD, &infop->si_signo);
1351         if (!retval && infop)
1352                 retval = put_user(0, &infop->si_errno);
1353         if (!retval && infop)
1354                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1355                                           ? CLD_TRAPPED : CLD_STOPPED),
1356                                   &infop->si_code);
1357         if (!retval && infop)
1358                 retval = put_user(exit_code, &infop->si_status);
1359         if (!retval && infop)
1360                 retval = put_user(p->pid, &infop->si_pid);
1361         if (!retval && infop)
1362                 retval = put_user(p->uid, &infop->si_uid);
1363         if (!retval)
1364                 retval = p->pid;
1365         put_task_struct(p);
1366
1367         BUG_ON(!retval);
1368         return retval;
1369 }
1370
1371 /*
1372  * Handle do_wait work for one task in a live, non-stopped state.
1373  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1374  * the lock and this task is uninteresting.  If we return nonzero, we have
1375  * released the lock and the system call should return.
1376  */
1377 static int wait_task_continued(struct task_struct *p, int noreap,
1378                                struct siginfo __user *infop,
1379                                int __user *stat_addr, struct rusage __user *ru)
1380 {
1381         int retval;
1382         pid_t pid;
1383         uid_t uid;
1384
1385         if (unlikely(!p->signal))
1386                 return 0;
1387
1388         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1389                 return 0;
1390
1391         spin_lock_irq(&p->sighand->siglock);
1392         /* Re-check with the lock held.  */
1393         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1394                 spin_unlock_irq(&p->sighand->siglock);
1395                 return 0;
1396         }
1397         if (!noreap)
1398                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1399         spin_unlock_irq(&p->sighand->siglock);
1400
1401         pid = p->pid;
1402         uid = p->uid;
1403         get_task_struct(p);
1404         read_unlock(&tasklist_lock);
1405
1406         if (!infop) {
1407                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1408                 put_task_struct(p);
1409                 if (!retval && stat_addr)
1410                         retval = put_user(0xffff, stat_addr);
1411                 if (!retval)
1412                         retval = p->pid;
1413         } else {
1414                 retval = wait_noreap_copyout(p, pid, uid,
1415                                              CLD_CONTINUED, SIGCONT,
1416                                              infop, ru);
1417                 BUG_ON(retval == 0);
1418         }
1419
1420         return retval;
1421 }
1422
1423
1424 static inline int my_ptrace_child(struct task_struct *p)
1425 {
1426         if (!(p->ptrace & PT_PTRACED))
1427                 return 0;
1428         if (!(p->ptrace & PT_ATTACHED))
1429                 return 1;
1430         /*
1431          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1432          * we are the attacher.  If we are the real parent, this is a race
1433          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1434          * which we have to switch the parent links, but has already set
1435          * the flags in p->ptrace.
1436          */
1437         return (p->parent != p->real_parent);
1438 }
1439
1440 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1441                     int __user *stat_addr, struct rusage __user *ru)
1442 {
1443         DECLARE_WAITQUEUE(wait, current);
1444         struct task_struct *tsk;
1445         int flag, retval;
1446
1447         add_wait_queue(&current->signal->wait_chldexit,&wait);
1448 repeat:
1449         /*
1450          * We will set this flag if we see any child that might later
1451          * match our criteria, even if we are not able to reap it yet.
1452          */
1453         flag = 0;
1454         current->state = TASK_INTERRUPTIBLE;
1455         read_lock(&tasklist_lock);
1456         tsk = current;
1457         do {
1458                 struct task_struct *p;
1459                 struct list_head *_p;
1460                 int ret;
1461
1462                 list_for_each(_p,&tsk->children) {
1463                         p = list_entry(_p, struct task_struct, sibling);
1464
1465                         ret = eligible_child(pid, options, p);
1466                         if (!ret)
1467                                 continue;
1468
1469                         switch (p->state) {
1470                         case TASK_TRACED:
1471                                 /*
1472                                  * When we hit the race with PTRACE_ATTACH,
1473                                  * we will not report this child.  But the
1474                                  * race means it has not yet been moved to
1475                                  * our ptrace_children list, so we need to
1476                                  * set the flag here to avoid a spurious ECHILD
1477                                  * when the race happens with the only child.
1478                                  */
1479                                 flag = 1;
1480                                 if (!my_ptrace_child(p))
1481                                         continue;
1482                                 /*FALLTHROUGH*/
1483                         case TASK_STOPPED:
1484                                 /*
1485                                  * It's stopped now, so it might later
1486                                  * continue, exit, or stop again.
1487                                  */
1488                                 flag = 1;
1489                                 if (!(options & WUNTRACED) &&
1490                                     !my_ptrace_child(p))
1491                                         continue;
1492                                 retval = wait_task_stopped(p, ret == 2,
1493                                                            (options & WNOWAIT),
1494                                                            infop,
1495                                                            stat_addr, ru);
1496                                 if (retval == -EAGAIN)
1497                                         goto repeat;
1498                                 if (retval != 0) /* He released the lock.  */
1499                                         goto end;
1500                                 break;
1501                         default:
1502                         // case EXIT_DEAD:
1503                                 if (p->exit_state == EXIT_DEAD)
1504                                         continue;
1505                         // case EXIT_ZOMBIE:
1506                                 if (p->exit_state == EXIT_ZOMBIE) {
1507                                         /*
1508                                          * Eligible but we cannot release
1509                                          * it yet:
1510                                          */
1511                                         if (ret == 2)
1512                                                 goto check_continued;
1513                                         if (!likely(options & WEXITED))
1514                                                 continue;
1515                                         retval = wait_task_zombie(
1516                                                 p, (options & WNOWAIT),
1517                                                 infop, stat_addr, ru);
1518                                         /* He released the lock.  */
1519                                         if (retval != 0)
1520                                                 goto end;
1521                                         break;
1522                                 }
1523 check_continued:
1524                                 /*
1525                                  * It's running now, so it might later
1526                                  * exit, stop, or stop and then continue.
1527                                  */
1528                                 flag = 1;
1529                                 if (!unlikely(options & WCONTINUED))
1530                                         continue;
1531                                 retval = wait_task_continued(
1532                                         p, (options & WNOWAIT),
1533                                         infop, stat_addr, ru);
1534                                 if (retval != 0) /* He released the lock.  */
1535                                         goto end;
1536                                 break;
1537                         }
1538                 }
1539                 if (!flag) {
1540                         list_for_each(_p, &tsk->ptrace_children) {
1541                                 p = list_entry(_p, struct task_struct,
1542                                                 ptrace_list);
1543                                 if (!eligible_child(pid, options, p))
1544                                         continue;
1545                                 flag = 1;
1546                                 break;
1547                         }
1548                 }
1549                 if (options & __WNOTHREAD)
1550                         break;
1551                 tsk = next_thread(tsk);
1552                 BUG_ON(tsk->signal != current->signal);
1553         } while (tsk != current);
1554
1555         read_unlock(&tasklist_lock);
1556         if (flag) {
1557                 retval = 0;
1558                 if (options & WNOHANG)
1559                         goto end;
1560                 retval = -ERESTARTSYS;
1561                 if (signal_pending(current))
1562                         goto end;
1563                 schedule();
1564                 goto repeat;
1565         }
1566         retval = -ECHILD;
1567 end:
1568         current->state = TASK_RUNNING;
1569         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1570         if (infop) {
1571                 if (retval > 0)
1572                 retval = 0;
1573                 else {
1574                         /*
1575                          * For a WNOHANG return, clear out all the fields
1576                          * we would set so the user can easily tell the
1577                          * difference.
1578                          */
1579                         if (!retval)
1580                                 retval = put_user(0, &infop->si_signo);
1581                         if (!retval)
1582                                 retval = put_user(0, &infop->si_errno);
1583                         if (!retval)
1584                                 retval = put_user(0, &infop->si_code);
1585                         if (!retval)
1586                                 retval = put_user(0, &infop->si_pid);
1587                         if (!retval)
1588                                 retval = put_user(0, &infop->si_uid);
1589                         if (!retval)
1590                                 retval = put_user(0, &infop->si_status);
1591                 }
1592         }
1593         return retval;
1594 }
1595
1596 asmlinkage long sys_waitid(int which, pid_t pid,
1597                            struct siginfo __user *infop, int options,
1598                            struct rusage __user *ru)
1599 {
1600         long ret;
1601
1602         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1603                 return -EINVAL;
1604         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1605                 return -EINVAL;
1606
1607         switch (which) {
1608         case P_ALL:
1609                 pid = -1;
1610                 break;
1611         case P_PID:
1612                 if (pid <= 0)
1613                         return -EINVAL;
1614                 break;
1615         case P_PGID:
1616                 if (pid <= 0)
1617                         return -EINVAL;
1618                 pid = -pid;
1619                 break;
1620         default:
1621                 return -EINVAL;
1622         }
1623
1624         ret = do_wait(pid, options, infop, NULL, ru);
1625
1626         /* avoid REGPARM breakage on x86: */
1627         prevent_tail_call(ret);
1628         return ret;
1629 }
1630
1631 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1632                           int options, struct rusage __user *ru)
1633 {
1634         long ret;
1635
1636         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1637                         __WNOTHREAD|__WCLONE|__WALL))
1638                 return -EINVAL;
1639         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1640
1641         /* avoid REGPARM breakage on x86: */
1642         prevent_tail_call(ret);
1643         return ret;
1644 }
1645
1646 #ifdef __ARCH_WANT_SYS_WAITPID
1647
1648 /*
1649  * sys_waitpid() remains for compatibility. waitpid() should be
1650  * implemented by calling sys_wait4() from libc.a.
1651  */
1652 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1653 {
1654         return sys_wait4(pid, stat_addr, options, NULL);
1655 }
1656
1657 #endif