header cleaning: don't include smp_lock.h when not used
[linux-3.10.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/module.h>
11 #include <linux/capability.h>
12 #include <linux/completion.h>
13 #include <linux/personality.h>
14 #include <linux/tty.h>
15 #include <linux/mnt_namespace.h>
16 #include <linux/key.h>
17 #include <linux/security.h>
18 #include <linux/cpu.h>
19 #include <linux/acct.h>
20 #include <linux/tsacct_kern.h>
21 #include <linux/file.h>
22 #include <linux/binfmts.h>
23 #include <linux/nsproxy.h>
24 #include <linux/pid_namespace.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
52 static void exit_mm(struct task_struct * tsk);
53
54 static void __unhash_process(struct task_struct *p)
55 {
56         nr_threads--;
57         detach_pid(p, PIDTYPE_PID);
58         if (thread_group_leader(p)) {
59                 detach_pid(p, PIDTYPE_PGID);
60                 detach_pid(p, PIDTYPE_SID);
61
62                 list_del_rcu(&p->tasks);
63                 __get_cpu_var(process_counts)--;
64         }
65         list_del_rcu(&p->thread_group);
66         remove_parent(p);
67 }
68
69 /*
70  * This function expects the tasklist_lock write-locked.
71  */
72 static void __exit_signal(struct task_struct *tsk)
73 {
74         struct signal_struct *sig = tsk->signal;
75         struct sighand_struct *sighand;
76
77         BUG_ON(!sig);
78         BUG_ON(!atomic_read(&sig->count));
79
80         rcu_read_lock();
81         sighand = rcu_dereference(tsk->sighand);
82         spin_lock(&sighand->siglock);
83
84         posix_cpu_timers_exit(tsk);
85         if (atomic_dec_and_test(&sig->count))
86                 posix_cpu_timers_exit_group(tsk);
87         else {
88                 /*
89                  * If there is any task waiting for the group exit
90                  * then notify it:
91                  */
92                 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
93                         wake_up_process(sig->group_exit_task);
94                         sig->group_exit_task = NULL;
95                 }
96                 if (tsk == sig->curr_target)
97                         sig->curr_target = next_thread(tsk);
98                 /*
99                  * Accumulate here the counters for all threads but the
100                  * group leader as they die, so they can be added into
101                  * the process-wide totals when those are taken.
102                  * The group leader stays around as a zombie as long
103                  * as there are other threads.  When it gets reaped,
104                  * the exit.c code will add its counts into these totals.
105                  * We won't ever get here for the group leader, since it
106                  * will have been the last reference on the signal_struct.
107                  */
108                 sig->utime = cputime_add(sig->utime, tsk->utime);
109                 sig->stime = cputime_add(sig->stime, tsk->stime);
110                 sig->min_flt += tsk->min_flt;
111                 sig->maj_flt += tsk->maj_flt;
112                 sig->nvcsw += tsk->nvcsw;
113                 sig->nivcsw += tsk->nivcsw;
114                 sig->sched_time += tsk->sched_time;
115                 sig = NULL; /* Marker for below. */
116         }
117
118         __unhash_process(tsk);
119
120         tsk->signal = NULL;
121         tsk->sighand = NULL;
122         spin_unlock(&sighand->siglock);
123         rcu_read_unlock();
124
125         __cleanup_sighand(sighand);
126         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
127         flush_sigqueue(&tsk->pending);
128         if (sig) {
129                 flush_sigqueue(&sig->shared_pending);
130                 taskstats_tgid_free(sig);
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  * The caller must hold rcu lock or the tasklist lock.
189  */
190 struct pid *session_of_pgrp(struct pid *pgrp)
191 {
192         struct task_struct *p;
193         struct pid *sid = NULL;
194
195         p = pid_task(pgrp, PIDTYPE_PGID);
196         if (p == NULL)
197                 p = pid_task(pgrp, PIDTYPE_PID);
198         if (p != NULL)
199                 sid = task_session(p);
200
201         return sid;
202 }
203
204 /*
205  * Determine if a process group is "orphaned", according to the POSIX
206  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
207  * by terminal-generated stop signals.  Newly orphaned process groups are
208  * to receive a SIGHUP and a SIGCONT.
209  *
210  * "I ask you, have you ever known what it is to be an orphan?"
211  */
212 static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
213 {
214         struct task_struct *p;
215         int ret = 1;
216
217         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
218                 if (p == ignored_task
219                                 || p->exit_state
220                                 || is_init(p->real_parent))
221                         continue;
222                 if (task_pgrp(p->real_parent) != pgrp &&
223                     task_session(p->real_parent) == task_session(p)) {
224                         ret = 0;
225                         break;
226                 }
227         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
228         return ret;     /* (sighing) "Often!" */
229 }
230
231 int is_current_pgrp_orphaned(void)
232 {
233         int retval;
234
235         read_lock(&tasklist_lock);
236         retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
237         read_unlock(&tasklist_lock);
238
239         return retval;
240 }
241
242 static int has_stopped_jobs(struct pid *pgrp)
243 {
244         int retval = 0;
245         struct task_struct *p;
246
247         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
248                 if (p->state != TASK_STOPPED)
249                         continue;
250                 retval = 1;
251                 break;
252         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
253         return retval;
254 }
255
256 /**
257  * reparent_to_init - Reparent the calling kernel thread to the init task of the pid space that the thread belongs to.
258  *
259  * If a kernel thread is launched as a result of a system call, or if
260  * it ever exits, it should generally reparent itself to init so that
261  * it is correctly cleaned up on exit.
262  *
263  * The various task state such as scheduling policy and priority may have
264  * been inherited from a user process, so we reset them to sane values here.
265  *
266  * NOTE that reparent_to_init() gives the caller full capabilities.
267  */
268 static void reparent_to_init(void)
269 {
270         write_lock_irq(&tasklist_lock);
271
272         ptrace_unlink(current);
273         /* Reparent to init */
274         remove_parent(current);
275         current->parent = child_reaper(current);
276         current->real_parent = child_reaper(current);
277         add_parent(current);
278
279         /* Set the exit signal to SIGCHLD so we signal init on exit */
280         current->exit_signal = SIGCHLD;
281
282         if (!has_rt_policy(current) && (task_nice(current) < 0))
283                 set_user_nice(current, 0);
284         /* cpus_allowed? */
285         /* rt_priority? */
286         /* signals? */
287         security_task_reparent_to_init(current);
288         memcpy(current->signal->rlim, init_task.signal->rlim,
289                sizeof(current->signal->rlim));
290         atomic_inc(&(INIT_USER->__count));
291         write_unlock_irq(&tasklist_lock);
292         switch_uid(INIT_USER);
293 }
294
295 void __set_special_pids(pid_t session, pid_t pgrp)
296 {
297         struct task_struct *curr = current->group_leader;
298
299         if (process_session(curr) != session) {
300                 detach_pid(curr, PIDTYPE_SID);
301                 set_signal_session(curr->signal, session);
302                 attach_pid(curr, PIDTYPE_SID, session);
303         }
304         if (process_group(curr) != pgrp) {
305                 detach_pid(curr, PIDTYPE_PGID);
306                 curr->signal->pgrp = pgrp;
307                 attach_pid(curr, PIDTYPE_PGID, pgrp);
308         }
309 }
310
311 static void set_special_pids(pid_t session, pid_t pgrp)
312 {
313         write_lock_irq(&tasklist_lock);
314         __set_special_pids(session, pgrp);
315         write_unlock_irq(&tasklist_lock);
316 }
317
318 /*
319  * Let kernel threads use this to say that they
320  * allow a certain signal (since daemonize() will
321  * have disabled all of them by default).
322  */
323 int allow_signal(int sig)
324 {
325         if (!valid_signal(sig) || sig < 1)
326                 return -EINVAL;
327
328         spin_lock_irq(&current->sighand->siglock);
329         sigdelset(&current->blocked, sig);
330         if (!current->mm) {
331                 /* Kernel threads handle their own signals.
332                    Let the signal code know it'll be handled, so
333                    that they don't get converted to SIGKILL or
334                    just silently dropped */
335                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
336         }
337         recalc_sigpending();
338         spin_unlock_irq(&current->sighand->siglock);
339         return 0;
340 }
341
342 EXPORT_SYMBOL(allow_signal);
343
344 int disallow_signal(int sig)
345 {
346         if (!valid_signal(sig) || sig < 1)
347                 return -EINVAL;
348
349         spin_lock_irq(&current->sighand->siglock);
350         sigaddset(&current->blocked, sig);
351         recalc_sigpending();
352         spin_unlock_irq(&current->sighand->siglock);
353         return 0;
354 }
355
356 EXPORT_SYMBOL(disallow_signal);
357
358 /*
359  *      Put all the gunge required to become a kernel thread without
360  *      attached user resources in one place where it belongs.
361  */
362
363 void daemonize(const char *name, ...)
364 {
365         va_list args;
366         struct fs_struct *fs;
367         sigset_t blocked;
368
369         va_start(args, name);
370         vsnprintf(current->comm, sizeof(current->comm), name, args);
371         va_end(args);
372
373         /*
374          * If we were started as result of loading a module, close all of the
375          * user space pages.  We don't need them, and if we didn't close them
376          * they would be locked into memory.
377          */
378         exit_mm(current);
379
380         set_special_pids(1, 1);
381         proc_clear_tty(current);
382
383         /* Block and flush all signals */
384         sigfillset(&blocked);
385         sigprocmask(SIG_BLOCK, &blocked, NULL);
386         flush_signals(current);
387
388         /* Become as one with the init task */
389
390         exit_fs(current);       /* current->fs->count--; */
391         fs = init_task.fs;
392         current->fs = fs;
393         atomic_inc(&fs->count);
394
395         exit_task_namespaces(current);
396         current->nsproxy = init_task.nsproxy;
397         get_task_namespaces(current);
398
399         exit_files(current);
400         current->files = init_task.files;
401         atomic_inc(&current->files->count);
402
403         reparent_to_init();
404 }
405
406 EXPORT_SYMBOL(daemonize);
407
408 static void close_files(struct files_struct * files)
409 {
410         int i, j;
411         struct fdtable *fdt;
412
413         j = 0;
414
415         /*
416          * It is safe to dereference the fd table without RCU or
417          * ->file_lock because this is the last reference to the
418          * files structure.
419          */
420         fdt = files_fdtable(files);
421         for (;;) {
422                 unsigned long set;
423                 i = j * __NFDBITS;
424                 if (i >= fdt->max_fds)
425                         break;
426                 set = fdt->open_fds->fds_bits[j++];
427                 while (set) {
428                         if (set & 1) {
429                                 struct file * file = xchg(&fdt->fd[i], NULL);
430                                 if (file) {
431                                         filp_close(file, files);
432                                         cond_resched();
433                                 }
434                         }
435                         i++;
436                         set >>= 1;
437                 }
438         }
439 }
440
441 struct files_struct *get_files_struct(struct task_struct *task)
442 {
443         struct files_struct *files;
444
445         task_lock(task);
446         files = task->files;
447         if (files)
448                 atomic_inc(&files->count);
449         task_unlock(task);
450
451         return files;
452 }
453
454 void fastcall put_files_struct(struct files_struct *files)
455 {
456         struct fdtable *fdt;
457
458         if (atomic_dec_and_test(&files->count)) {
459                 close_files(files);
460                 /*
461                  * Free the fd and fdset arrays if we expanded them.
462                  * If the fdtable was embedded, pass files for freeing
463                  * at the end of the RCU grace period. Otherwise,
464                  * you can free files immediately.
465                  */
466                 fdt = files_fdtable(files);
467                 if (fdt != &files->fdtab)
468                         kmem_cache_free(files_cachep, files);
469                 free_fdtable(fdt);
470         }
471 }
472
473 EXPORT_SYMBOL(put_files_struct);
474
475 void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
476 {
477         struct files_struct *old;
478
479         old = tsk->files;
480         task_lock(tsk);
481         tsk->files = files;
482         task_unlock(tsk);
483         put_files_struct(old);
484 }
485 EXPORT_SYMBOL(reset_files_struct);
486
487 static inline void __exit_files(struct task_struct *tsk)
488 {
489         struct files_struct * files = tsk->files;
490
491         if (files) {
492                 task_lock(tsk);
493                 tsk->files = NULL;
494                 task_unlock(tsk);
495                 put_files_struct(files);
496         }
497 }
498
499 void exit_files(struct task_struct *tsk)
500 {
501         __exit_files(tsk);
502 }
503
504 static inline void __put_fs_struct(struct fs_struct *fs)
505 {
506         /* No need to hold fs->lock if we are killing it */
507         if (atomic_dec_and_test(&fs->count)) {
508                 dput(fs->root);
509                 mntput(fs->rootmnt);
510                 dput(fs->pwd);
511                 mntput(fs->pwdmnt);
512                 if (fs->altroot) {
513                         dput(fs->altroot);
514                         mntput(fs->altrootmnt);
515                 }
516                 kmem_cache_free(fs_cachep, fs);
517         }
518 }
519
520 void put_fs_struct(struct fs_struct *fs)
521 {
522         __put_fs_struct(fs);
523 }
524
525 static inline void __exit_fs(struct task_struct *tsk)
526 {
527         struct fs_struct * fs = tsk->fs;
528
529         if (fs) {
530                 task_lock(tsk);
531                 tsk->fs = NULL;
532                 task_unlock(tsk);
533                 __put_fs_struct(fs);
534         }
535 }
536
537 void exit_fs(struct task_struct *tsk)
538 {
539         __exit_fs(tsk);
540 }
541
542 EXPORT_SYMBOL_GPL(exit_fs);
543
544 /*
545  * Turn us into a lazy TLB process if we
546  * aren't already..
547  */
548 static void exit_mm(struct task_struct * tsk)
549 {
550         struct mm_struct *mm = tsk->mm;
551
552         mm_release(tsk, mm);
553         if (!mm)
554                 return;
555         /*
556          * Serialize with any possible pending coredump.
557          * We must hold mmap_sem around checking core_waiters
558          * and clearing tsk->mm.  The core-inducing thread
559          * will increment core_waiters for each thread in the
560          * group with ->mm != NULL.
561          */
562         down_read(&mm->mmap_sem);
563         if (mm->core_waiters) {
564                 up_read(&mm->mmap_sem);
565                 down_write(&mm->mmap_sem);
566                 if (!--mm->core_waiters)
567                         complete(mm->core_startup_done);
568                 up_write(&mm->mmap_sem);
569
570                 wait_for_completion(&mm->core_done);
571                 down_read(&mm->mmap_sem);
572         }
573         atomic_inc(&mm->mm_count);
574         BUG_ON(mm != tsk->active_mm);
575         /* more a memory barrier than a real lock */
576         task_lock(tsk);
577         tsk->mm = NULL;
578         up_read(&mm->mmap_sem);
579         enter_lazy_tlb(mm, current);
580         task_unlock(tsk);
581         mmput(mm);
582 }
583
584 static inline void
585 choose_new_parent(struct task_struct *p, struct task_struct *reaper)
586 {
587         /*
588          * Make sure we're not reparenting to ourselves and that
589          * the parent is not a zombie.
590          */
591         BUG_ON(p == reaper || reaper->exit_state);
592         p->real_parent = reaper;
593 }
594
595 static void
596 reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
597 {
598         if (p->pdeath_signal)
599                 /* We already hold the tasklist_lock here.  */
600                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
601
602         /* Move the child from its dying parent to the new one.  */
603         if (unlikely(traced)) {
604                 /* Preserve ptrace links if someone else is tracing this child.  */
605                 list_del_init(&p->ptrace_list);
606                 if (p->parent != p->real_parent)
607                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
608         } else {
609                 /* If this child is being traced, then we're the one tracing it
610                  * anyway, so let go of it.
611                  */
612                 p->ptrace = 0;
613                 remove_parent(p);
614                 p->parent = p->real_parent;
615                 add_parent(p);
616
617                 if (p->state == TASK_TRACED) {
618                         /*
619                          * If it was at a trace stop, turn it into
620                          * a normal stop since it's no longer being
621                          * traced.
622                          */
623                         ptrace_untrace(p);
624                 }
625         }
626
627         /* If this is a threaded reparent there is no need to
628          * notify anyone anything has happened.
629          */
630         if (p->real_parent->group_leader == father->group_leader)
631                 return;
632
633         /* We don't want people slaying init.  */
634         if (p->exit_signal != -1)
635                 p->exit_signal = SIGCHLD;
636
637         /* If we'd notified the old parent about this child's death,
638          * also notify the new parent.
639          */
640         if (!traced && p->exit_state == EXIT_ZOMBIE &&
641             p->exit_signal != -1 && thread_group_empty(p))
642                 do_notify_parent(p, p->exit_signal);
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 ((task_pgrp(p) != task_pgrp(father)) &&
651             (task_session(p) == task_session(father))) {
652                 struct pid *pgrp = task_pgrp(p);
653
654                 if (will_become_orphaned_pgrp(pgrp, NULL) &&
655                     has_stopped_jobs(pgrp)) {
656                         __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
657                         __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
658                 }
659         }
660 }
661
662 /*
663  * When we die, we re-parent all our children.
664  * Try to give them to another thread in our thread
665  * group, and if no such member exists, give it to
666  * the child reaper process (ie "init") in our pid
667  * space.
668  */
669 static void
670 forget_original_parent(struct task_struct *father, struct list_head *to_release)
671 {
672         struct task_struct *p, *reaper = father;
673         struct list_head *_p, *_n;
674
675         do {
676                 reaper = next_thread(reaper);
677                 if (reaper == father) {
678                         reaper = child_reaper(father);
679                         break;
680                 }
681         } while (reaper->exit_state);
682
683         /*
684          * There are only two places where our children can be:
685          *
686          * - in our child list
687          * - in our ptraced child list
688          *
689          * Search them and reparent children.
690          */
691         list_for_each_safe(_p, _n, &father->children) {
692                 int ptrace;
693                 p = list_entry(_p, struct task_struct, sibling);
694
695                 ptrace = p->ptrace;
696
697                 /* if father isn't the real parent, then ptrace must be enabled */
698                 BUG_ON(father != p->real_parent && !ptrace);
699
700                 if (father == p->real_parent) {
701                         /* reparent with a reaper, real father it's us */
702                         choose_new_parent(p, reaper);
703                         reparent_thread(p, father, 0);
704                 } else {
705                         /* reparent ptraced task to its real parent */
706                         __ptrace_unlink (p);
707                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
708                             thread_group_empty(p))
709                                 do_notify_parent(p, p->exit_signal);
710                 }
711
712                 /*
713                  * if the ptraced child is a zombie with exit_signal == -1
714                  * we must collect it before we exit, or it will remain
715                  * zombie forever since we prevented it from self-reap itself
716                  * while it was being traced by us, to be able to see it in wait4.
717                  */
718                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
719                         list_add(&p->ptrace_list, to_release);
720         }
721         list_for_each_safe(_p, _n, &father->ptrace_children) {
722                 p = list_entry(_p, struct task_struct, ptrace_list);
723                 choose_new_parent(p, reaper);
724                 reparent_thread(p, father, 1);
725         }
726 }
727
728 /*
729  * Send signals to all our closest relatives so that they know
730  * to properly mourn us..
731  */
732 static void exit_notify(struct task_struct *tsk)
733 {
734         int state;
735         struct task_struct *t;
736         struct list_head ptrace_dead, *_p, *_n;
737         struct pid *pgrp;
738
739         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
740             && !thread_group_empty(tsk)) {
741                 /*
742                  * This occurs when there was a race between our exit
743                  * syscall and a group signal choosing us as the one to
744                  * wake up.  It could be that we are the only thread
745                  * alerted to check for pending signals, but another thread
746                  * should be woken now to take the signal since we will not.
747                  * Now we'll wake all the threads in the group just to make
748                  * sure someone gets all the pending signals.
749                  */
750                 read_lock(&tasklist_lock);
751                 spin_lock_irq(&tsk->sighand->siglock);
752                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
753                         if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
754                                 recalc_sigpending_tsk(t);
755                                 if (signal_pending(t))
756                                         signal_wake_up(t, 0);
757                         }
758                 spin_unlock_irq(&tsk->sighand->siglock);
759                 read_unlock(&tasklist_lock);
760         }
761
762         write_lock_irq(&tasklist_lock);
763
764         /*
765          * This does two things:
766          *
767          * A.  Make init inherit all the child processes
768          * B.  Check to see if any process groups have become orphaned
769          *      as a result of our exiting, and if they have any stopped
770          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
771          */
772
773         INIT_LIST_HEAD(&ptrace_dead);
774         forget_original_parent(tsk, &ptrace_dead);
775         BUG_ON(!list_empty(&tsk->children));
776         BUG_ON(!list_empty(&tsk->ptrace_children));
777
778         /*
779          * Check to see if any process groups have become orphaned
780          * as a result of our exiting, and if they have any stopped
781          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
782          *
783          * Case i: Our father is in a different pgrp than we are
784          * and we were the only connection outside, so our pgrp
785          * is about to become orphaned.
786          */
787          
788         t = tsk->real_parent;
789         
790         pgrp = task_pgrp(tsk);
791         if ((task_pgrp(t) != pgrp) &&
792             (task_session(t) == task_session(tsk)) &&
793             will_become_orphaned_pgrp(pgrp, tsk) &&
794             has_stopped_jobs(pgrp)) {
795                 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
796                 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
797         }
798
799         /* Let father know we died 
800          *
801          * Thread signals are configurable, but you aren't going to use
802          * that to send signals to arbitary processes. 
803          * That stops right now.
804          *
805          * If the parent exec id doesn't match the exec id we saved
806          * when we started then we know the parent has changed security
807          * domain.
808          *
809          * If our self_exec id doesn't match our parent_exec_id then
810          * we have changed execution domain as these two values started
811          * the same after a fork.
812          *      
813          */
814         
815         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
816             ( tsk->parent_exec_id != t->self_exec_id  ||
817               tsk->self_exec_id != tsk->parent_exec_id)
818             && !capable(CAP_KILL))
819                 tsk->exit_signal = SIGCHLD;
820
821
822         /* If something other than our normal parent is ptracing us, then
823          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
824          * only has special meaning to our real parent.
825          */
826         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
827                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
828                 do_notify_parent(tsk, signal);
829         } else if (tsk->ptrace) {
830                 do_notify_parent(tsk, SIGCHLD);
831         }
832
833         state = EXIT_ZOMBIE;
834         if (tsk->exit_signal == -1 &&
835             (likely(tsk->ptrace == 0) ||
836              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
837                 state = EXIT_DEAD;
838         tsk->exit_state = state;
839
840         write_unlock_irq(&tasklist_lock);
841
842         list_for_each_safe(_p, _n, &ptrace_dead) {
843                 list_del_init(_p);
844                 t = list_entry(_p, struct task_struct, ptrace_list);
845                 release_task(t);
846         }
847
848         /* If the process is dead, release it - nobody will wait for it */
849         if (state == EXIT_DEAD)
850                 release_task(tsk);
851 }
852
853 fastcall NORET_TYPE void do_exit(long code)
854 {
855         struct task_struct *tsk = current;
856         int group_dead;
857
858         profile_task_exit(tsk);
859
860         WARN_ON(atomic_read(&tsk->fs_excl));
861
862         if (unlikely(in_interrupt()))
863                 panic("Aiee, killing interrupt handler!");
864         if (unlikely(!tsk->pid))
865                 panic("Attempted to kill the idle task!");
866         if (unlikely(tsk == child_reaper(tsk))) {
867                 if (tsk->nsproxy->pid_ns != &init_pid_ns)
868                         tsk->nsproxy->pid_ns->child_reaper = init_pid_ns.child_reaper;
869                 else
870                         panic("Attempted to kill init!");
871         }
872
873
874         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
875                 current->ptrace_message = code;
876                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
877         }
878
879         /*
880          * We're taking recursive faults here in do_exit. Safest is to just
881          * leave this task alone and wait for reboot.
882          */
883         if (unlikely(tsk->flags & PF_EXITING)) {
884                 printk(KERN_ALERT
885                         "Fixing recursive fault but reboot is needed!\n");
886                 if (tsk->io_context)
887                         exit_io_context();
888                 set_current_state(TASK_UNINTERRUPTIBLE);
889                 schedule();
890         }
891
892         tsk->flags |= PF_EXITING;
893
894         if (unlikely(in_atomic()))
895                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
896                                 current->comm, current->pid,
897                                 preempt_count());
898
899         acct_update_integrals(tsk);
900         if (tsk->mm) {
901                 update_hiwater_rss(tsk->mm);
902                 update_hiwater_vm(tsk->mm);
903         }
904         group_dead = atomic_dec_and_test(&tsk->signal->live);
905         if (group_dead) {
906                 hrtimer_cancel(&tsk->signal->real_timer);
907                 exit_itimers(tsk->signal);
908         }
909         acct_collect(code, group_dead);
910         if (unlikely(tsk->robust_list))
911                 exit_robust_list(tsk);
912 #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
913         if (unlikely(tsk->compat_robust_list))
914                 compat_exit_robust_list(tsk);
915 #endif
916         if (unlikely(tsk->audit_context))
917                 audit_free(tsk);
918
919         taskstats_exit(tsk, group_dead);
920
921         exit_mm(tsk);
922
923         if (group_dead)
924                 acct_process();
925         exit_sem(tsk);
926         __exit_files(tsk);
927         __exit_fs(tsk);
928         exit_thread();
929         cpuset_exit(tsk);
930         exit_keys(tsk);
931
932         if (group_dead && tsk->signal->leader)
933                 disassociate_ctty(1);
934
935         module_put(task_thread_info(tsk)->exec_domain->module);
936         if (tsk->binfmt)
937                 module_put(tsk->binfmt->module);
938
939         tsk->exit_code = code;
940         proc_exit_connector(tsk);
941         exit_task_namespaces(tsk);
942         exit_notify(tsk);
943 #ifdef CONFIG_NUMA
944         mpol_free(tsk->mempolicy);
945         tsk->mempolicy = NULL;
946 #endif
947         /*
948          * This must happen late, after the PID is not
949          * hashed anymore:
950          */
951         if (unlikely(!list_empty(&tsk->pi_state_list)))
952                 exit_pi_state_list(tsk);
953         if (unlikely(current->pi_state_cache))
954                 kfree(current->pi_state_cache);
955         /*
956          * Make sure we are holding no locks:
957          */
958         debug_check_no_locks_held(tsk);
959
960         if (tsk->io_context)
961                 exit_io_context();
962
963         if (tsk->splice_pipe)
964                 __free_pipe_info(tsk->splice_pipe);
965
966         preempt_disable();
967         /* causes final put_task_struct in finish_task_switch(). */
968         tsk->state = TASK_DEAD;
969
970         schedule();
971         BUG();
972         /* Avoid "noreturn function does return".  */
973         for (;;)
974                 cpu_relax();    /* For when BUG is null */
975 }
976
977 EXPORT_SYMBOL_GPL(do_exit);
978
979 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
980 {
981         if (comp)
982                 complete(comp);
983
984         do_exit(code);
985 }
986
987 EXPORT_SYMBOL(complete_and_exit);
988
989 asmlinkage long sys_exit(int error_code)
990 {
991         do_exit((error_code&0xff)<<8);
992 }
993
994 /*
995  * Take down every thread in the group.  This is called by fatal signals
996  * as well as by sys_exit_group (below).
997  */
998 NORET_TYPE void
999 do_group_exit(int exit_code)
1000 {
1001         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1002
1003         if (current->signal->flags & SIGNAL_GROUP_EXIT)
1004                 exit_code = current->signal->group_exit_code;
1005         else if (!thread_group_empty(current)) {
1006                 struct signal_struct *const sig = current->signal;
1007                 struct sighand_struct *const sighand = current->sighand;
1008                 spin_lock_irq(&sighand->siglock);
1009                 if (sig->flags & SIGNAL_GROUP_EXIT)
1010                         /* Another thread got here before we took the lock.  */
1011                         exit_code = sig->group_exit_code;
1012                 else {
1013                         sig->group_exit_code = exit_code;
1014                         zap_other_threads(current);
1015                 }
1016                 spin_unlock_irq(&sighand->siglock);
1017         }
1018
1019         do_exit(exit_code);
1020         /* NOTREACHED */
1021 }
1022
1023 /*
1024  * this kills every thread in the thread group. Note that any externally
1025  * wait4()-ing process will get the correct exit code - even if this
1026  * thread is not the thread group leader.
1027  */
1028 asmlinkage void sys_exit_group(int error_code)
1029 {
1030         do_group_exit((error_code & 0xff) << 8);
1031 }
1032
1033 static int eligible_child(pid_t pid, int options, struct task_struct *p)
1034 {
1035         int err;
1036
1037         if (pid > 0) {
1038                 if (p->pid != pid)
1039                         return 0;
1040         } else if (!pid) {
1041                 if (process_group(p) != process_group(current))
1042                         return 0;
1043         } else if (pid != -1) {
1044                 if (process_group(p) != -pid)
1045                         return 0;
1046         }
1047
1048         /*
1049          * Do not consider detached threads that are
1050          * not ptraced:
1051          */
1052         if (p->exit_signal == -1 && !p->ptrace)
1053                 return 0;
1054
1055         /* Wait for all children (clone and not) if __WALL is set;
1056          * otherwise, wait for clone children *only* if __WCLONE is
1057          * set; otherwise, wait for non-clone children *only*.  (Note:
1058          * A "clone" child here is one that reports to its parent
1059          * using a signal other than SIGCHLD.) */
1060         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1061             && !(options & __WALL))
1062                 return 0;
1063         /*
1064          * Do not consider thread group leaders that are
1065          * in a non-empty thread group:
1066          */
1067         if (delay_group_leader(p))
1068                 return 2;
1069
1070         err = security_task_wait(p);
1071         if (err)
1072                 return err;
1073
1074         return 1;
1075 }
1076
1077 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1078                                int why, int status,
1079                                struct siginfo __user *infop,
1080                                struct rusage __user *rusagep)
1081 {
1082         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1083
1084         put_task_struct(p);
1085         if (!retval)
1086                 retval = put_user(SIGCHLD, &infop->si_signo);
1087         if (!retval)
1088                 retval = put_user(0, &infop->si_errno);
1089         if (!retval)
1090                 retval = put_user((short)why, &infop->si_code);
1091         if (!retval)
1092                 retval = put_user(pid, &infop->si_pid);
1093         if (!retval)
1094                 retval = put_user(uid, &infop->si_uid);
1095         if (!retval)
1096                 retval = put_user(status, &infop->si_status);
1097         if (!retval)
1098                 retval = pid;
1099         return retval;
1100 }
1101
1102 /*
1103  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1104  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1105  * the lock and this task is uninteresting.  If we return nonzero, we have
1106  * released the lock and the system call should return.
1107  */
1108 static int wait_task_zombie(struct task_struct *p, int noreap,
1109                             struct siginfo __user *infop,
1110                             int __user *stat_addr, struct rusage __user *ru)
1111 {
1112         unsigned long state;
1113         int retval;
1114         int status;
1115
1116         if (unlikely(noreap)) {
1117                 pid_t pid = p->pid;
1118                 uid_t uid = p->uid;
1119                 int exit_code = p->exit_code;
1120                 int why, status;
1121
1122                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1123                         return 0;
1124                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1125                         return 0;
1126                 get_task_struct(p);
1127                 read_unlock(&tasklist_lock);
1128                 if ((exit_code & 0x7f) == 0) {
1129                         why = CLD_EXITED;
1130                         status = exit_code >> 8;
1131                 } else {
1132                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1133                         status = exit_code & 0x7f;
1134                 }
1135                 return wait_noreap_copyout(p, pid, uid, why,
1136                                            status, infop, ru);
1137         }
1138
1139         /*
1140          * Try to move the task's state to DEAD
1141          * only one thread is allowed to do this:
1142          */
1143         state = xchg(&p->exit_state, EXIT_DEAD);
1144         if (state != EXIT_ZOMBIE) {
1145                 BUG_ON(state != EXIT_DEAD);
1146                 return 0;
1147         }
1148         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1149                 /*
1150                  * This can only happen in a race with a ptraced thread
1151                  * dying on another processor.
1152                  */
1153                 return 0;
1154         }
1155
1156         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1157                 struct signal_struct *psig;
1158                 struct signal_struct *sig;
1159
1160                 /*
1161                  * The resource counters for the group leader are in its
1162                  * own task_struct.  Those for dead threads in the group
1163                  * are in its signal_struct, as are those for the child
1164                  * processes it has previously reaped.  All these
1165                  * accumulate in the parent's signal_struct c* fields.
1166                  *
1167                  * We don't bother to take a lock here to protect these
1168                  * p->signal fields, because they are only touched by
1169                  * __exit_signal, which runs with tasklist_lock
1170                  * write-locked anyway, and so is excluded here.  We do
1171                  * need to protect the access to p->parent->signal fields,
1172                  * as other threads in the parent group can be right
1173                  * here reaping other children at the same time.
1174                  */
1175                 spin_lock_irq(&p->parent->sighand->siglock);
1176                 psig = p->parent->signal;
1177                 sig = p->signal;
1178                 psig->cutime =
1179                         cputime_add(psig->cutime,
1180                         cputime_add(p->utime,
1181                         cputime_add(sig->utime,
1182                                     sig->cutime)));
1183                 psig->cstime =
1184                         cputime_add(psig->cstime,
1185                         cputime_add(p->stime,
1186                         cputime_add(sig->stime,
1187                                     sig->cstime)));
1188                 psig->cmin_flt +=
1189                         p->min_flt + sig->min_flt + sig->cmin_flt;
1190                 psig->cmaj_flt +=
1191                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1192                 psig->cnvcsw +=
1193                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1194                 psig->cnivcsw +=
1195                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1196                 spin_unlock_irq(&p->parent->sighand->siglock);
1197         }
1198
1199         /*
1200          * Now we are sure this task is interesting, and no other
1201          * thread can reap it because we set its state to EXIT_DEAD.
1202          */
1203         read_unlock(&tasklist_lock);
1204
1205         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1206         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1207                 ? p->signal->group_exit_code : p->exit_code;
1208         if (!retval && stat_addr)
1209                 retval = put_user(status, stat_addr);
1210         if (!retval && infop)
1211                 retval = put_user(SIGCHLD, &infop->si_signo);
1212         if (!retval && infop)
1213                 retval = put_user(0, &infop->si_errno);
1214         if (!retval && infop) {
1215                 int why;
1216
1217                 if ((status & 0x7f) == 0) {
1218                         why = CLD_EXITED;
1219                         status >>= 8;
1220                 } else {
1221                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1222                         status &= 0x7f;
1223                 }
1224                 retval = put_user((short)why, &infop->si_code);
1225                 if (!retval)
1226                         retval = put_user(status, &infop->si_status);
1227         }
1228         if (!retval && infop)
1229                 retval = put_user(p->pid, &infop->si_pid);
1230         if (!retval && infop)
1231                 retval = put_user(p->uid, &infop->si_uid);
1232         if (retval) {
1233                 // TODO: is this safe?
1234                 p->exit_state = EXIT_ZOMBIE;
1235                 return retval;
1236         }
1237         retval = p->pid;
1238         if (p->real_parent != p->parent) {
1239                 write_lock_irq(&tasklist_lock);
1240                 /* Double-check with lock held.  */
1241                 if (p->real_parent != p->parent) {
1242                         __ptrace_unlink(p);
1243                         // TODO: is this safe?
1244                         p->exit_state = EXIT_ZOMBIE;
1245                         /*
1246                          * If this is not a detached task, notify the parent.
1247                          * If it's still not detached after that, don't release
1248                          * it now.
1249                          */
1250                         if (p->exit_signal != -1) {
1251                                 do_notify_parent(p, p->exit_signal);
1252                                 if (p->exit_signal != -1)
1253                                         p = NULL;
1254                         }
1255                 }
1256                 write_unlock_irq(&tasklist_lock);
1257         }
1258         if (p != NULL)
1259                 release_task(p);
1260         BUG_ON(!retval);
1261         return retval;
1262 }
1263
1264 /*
1265  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1266  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1267  * the lock and this task is uninteresting.  If we return nonzero, we have
1268  * released the lock and the system call should return.
1269  */
1270 static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1271                              int noreap, struct siginfo __user *infop,
1272                              int __user *stat_addr, struct rusage __user *ru)
1273 {
1274         int retval, exit_code;
1275
1276         if (!p->exit_code)
1277                 return 0;
1278         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1279             p->signal && p->signal->group_stop_count > 0)
1280                 /*
1281                  * A group stop is in progress and this is the group leader.
1282                  * We won't report until all threads have stopped.
1283                  */
1284                 return 0;
1285
1286         /*
1287          * Now we are pretty sure this task is interesting.
1288          * Make sure it doesn't get reaped out from under us while we
1289          * give up the lock and then examine it below.  We don't want to
1290          * keep holding onto the tasklist_lock while we call getrusage and
1291          * possibly take page faults for user memory.
1292          */
1293         get_task_struct(p);
1294         read_unlock(&tasklist_lock);
1295
1296         if (unlikely(noreap)) {
1297                 pid_t pid = p->pid;
1298                 uid_t uid = p->uid;
1299                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1300
1301                 exit_code = p->exit_code;
1302                 if (unlikely(!exit_code) ||
1303                     unlikely(p->state & TASK_TRACED))
1304                         goto bail_ref;
1305                 return wait_noreap_copyout(p, pid, uid,
1306                                            why, (exit_code << 8) | 0x7f,
1307                                            infop, ru);
1308         }
1309
1310         write_lock_irq(&tasklist_lock);
1311
1312         /*
1313          * This uses xchg to be atomic with the thread resuming and setting
1314          * it.  It must also be done with the write lock held to prevent a
1315          * race with the EXIT_ZOMBIE case.
1316          */
1317         exit_code = xchg(&p->exit_code, 0);
1318         if (unlikely(p->exit_state)) {
1319                 /*
1320                  * The task resumed and then died.  Let the next iteration
1321                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1322                  * already be zero here if it resumed and did _exit(0).
1323                  * The task itself is dead and won't touch exit_code again;
1324                  * other processors in this function are locked out.
1325                  */
1326                 p->exit_code = exit_code;
1327                 exit_code = 0;
1328         }
1329         if (unlikely(exit_code == 0)) {
1330                 /*
1331                  * Another thread in this function got to it first, or it
1332                  * resumed, or it resumed and then died.
1333                  */
1334                 write_unlock_irq(&tasklist_lock);
1335 bail_ref:
1336                 put_task_struct(p);
1337                 /*
1338                  * We are returning to the wait loop without having successfully
1339                  * removed the process and having released the lock. We cannot
1340                  * continue, since the "p" task pointer is potentially stale.
1341                  *
1342                  * Return -EAGAIN, and do_wait() will restart the loop from the
1343                  * beginning. Do _not_ re-acquire the lock.
1344                  */
1345                 return -EAGAIN;
1346         }
1347
1348         /* move to end of parent's list to avoid starvation */
1349         remove_parent(p);
1350         add_parent(p);
1351
1352         write_unlock_irq(&tasklist_lock);
1353
1354         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1355         if (!retval && stat_addr)
1356                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1357         if (!retval && infop)
1358                 retval = put_user(SIGCHLD, &infop->si_signo);
1359         if (!retval && infop)
1360                 retval = put_user(0, &infop->si_errno);
1361         if (!retval && infop)
1362                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1363                                           ? CLD_TRAPPED : CLD_STOPPED),
1364                                   &infop->si_code);
1365         if (!retval && infop)
1366                 retval = put_user(exit_code, &infop->si_status);
1367         if (!retval && infop)
1368                 retval = put_user(p->pid, &infop->si_pid);
1369         if (!retval && infop)
1370                 retval = put_user(p->uid, &infop->si_uid);
1371         if (!retval)
1372                 retval = p->pid;
1373         put_task_struct(p);
1374
1375         BUG_ON(!retval);
1376         return retval;
1377 }
1378
1379 /*
1380  * Handle do_wait work for one task in a live, non-stopped state.
1381  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1382  * the lock and this task is uninteresting.  If we return nonzero, we have
1383  * released the lock and the system call should return.
1384  */
1385 static int wait_task_continued(struct task_struct *p, int noreap,
1386                                struct siginfo __user *infop,
1387                                int __user *stat_addr, struct rusage __user *ru)
1388 {
1389         int retval;
1390         pid_t pid;
1391         uid_t uid;
1392
1393         if (unlikely(!p->signal))
1394                 return 0;
1395
1396         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1397                 return 0;
1398
1399         spin_lock_irq(&p->sighand->siglock);
1400         /* Re-check with the lock held.  */
1401         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1402                 spin_unlock_irq(&p->sighand->siglock);
1403                 return 0;
1404         }
1405         if (!noreap)
1406                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1407         spin_unlock_irq(&p->sighand->siglock);
1408
1409         pid = p->pid;
1410         uid = p->uid;
1411         get_task_struct(p);
1412         read_unlock(&tasklist_lock);
1413
1414         if (!infop) {
1415                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1416                 put_task_struct(p);
1417                 if (!retval && stat_addr)
1418                         retval = put_user(0xffff, stat_addr);
1419                 if (!retval)
1420                         retval = p->pid;
1421         } else {
1422                 retval = wait_noreap_copyout(p, pid, uid,
1423                                              CLD_CONTINUED, SIGCONT,
1424                                              infop, ru);
1425                 BUG_ON(retval == 0);
1426         }
1427
1428         return retval;
1429 }
1430
1431
1432 static inline int my_ptrace_child(struct task_struct *p)
1433 {
1434         if (!(p->ptrace & PT_PTRACED))
1435                 return 0;
1436         if (!(p->ptrace & PT_ATTACHED))
1437                 return 1;
1438         /*
1439          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1440          * we are the attacher.  If we are the real parent, this is a race
1441          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1442          * which we have to switch the parent links, but has already set
1443          * the flags in p->ptrace.
1444          */
1445         return (p->parent != p->real_parent);
1446 }
1447
1448 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1449                     int __user *stat_addr, struct rusage __user *ru)
1450 {
1451         DECLARE_WAITQUEUE(wait, current);
1452         struct task_struct *tsk;
1453         int flag, retval;
1454         int allowed, denied;
1455
1456         add_wait_queue(&current->signal->wait_chldexit,&wait);
1457 repeat:
1458         /*
1459          * We will set this flag if we see any child that might later
1460          * match our criteria, even if we are not able to reap it yet.
1461          */
1462         flag = 0;
1463         allowed = denied = 0;
1464         current->state = TASK_INTERRUPTIBLE;
1465         read_lock(&tasklist_lock);
1466         tsk = current;
1467         do {
1468                 struct task_struct *p;
1469                 struct list_head *_p;
1470                 int ret;
1471
1472                 list_for_each(_p,&tsk->children) {
1473                         p = list_entry(_p, struct task_struct, sibling);
1474
1475                         ret = eligible_child(pid, options, p);
1476                         if (!ret)
1477                                 continue;
1478
1479                         if (unlikely(ret < 0)) {
1480                                 denied = ret;
1481                                 continue;
1482                         }
1483                         allowed = 1;
1484
1485                         switch (p->state) {
1486                         case TASK_TRACED:
1487                                 /*
1488                                  * When we hit the race with PTRACE_ATTACH,
1489                                  * we will not report this child.  But the
1490                                  * race means it has not yet been moved to
1491                                  * our ptrace_children list, so we need to
1492                                  * set the flag here to avoid a spurious ECHILD
1493                                  * when the race happens with the only child.
1494                                  */
1495                                 flag = 1;
1496                                 if (!my_ptrace_child(p))
1497                                         continue;
1498                                 /*FALLTHROUGH*/
1499                         case TASK_STOPPED:
1500                                 /*
1501                                  * It's stopped now, so it might later
1502                                  * continue, exit, or stop again.
1503                                  */
1504                                 flag = 1;
1505                                 if (!(options & WUNTRACED) &&
1506                                     !my_ptrace_child(p))
1507                                         continue;
1508                                 retval = wait_task_stopped(p, ret == 2,
1509                                                            (options & WNOWAIT),
1510                                                            infop,
1511                                                            stat_addr, ru);
1512                                 if (retval == -EAGAIN)
1513                                         goto repeat;
1514                                 if (retval != 0) /* He released the lock.  */
1515                                         goto end;
1516                                 break;
1517                         default:
1518                         // case EXIT_DEAD:
1519                                 if (p->exit_state == EXIT_DEAD)
1520                                         continue;
1521                         // case EXIT_ZOMBIE:
1522                                 if (p->exit_state == EXIT_ZOMBIE) {
1523                                         /*
1524                                          * Eligible but we cannot release
1525                                          * it yet:
1526                                          */
1527                                         if (ret == 2)
1528                                                 goto check_continued;
1529                                         if (!likely(options & WEXITED))
1530                                                 continue;
1531                                         retval = wait_task_zombie(
1532                                                 p, (options & WNOWAIT),
1533                                                 infop, stat_addr, ru);
1534                                         /* He released the lock.  */
1535                                         if (retval != 0)
1536                                                 goto end;
1537                                         break;
1538                                 }
1539 check_continued:
1540                                 /*
1541                                  * It's running now, so it might later
1542                                  * exit, stop, or stop and then continue.
1543                                  */
1544                                 flag = 1;
1545                                 if (!unlikely(options & WCONTINUED))
1546                                         continue;
1547                                 retval = wait_task_continued(
1548                                         p, (options & WNOWAIT),
1549                                         infop, stat_addr, ru);
1550                                 if (retval != 0) /* He released the lock.  */
1551                                         goto end;
1552                                 break;
1553                         }
1554                 }
1555                 if (!flag) {
1556                         list_for_each(_p, &tsk->ptrace_children) {
1557                                 p = list_entry(_p, struct task_struct,
1558                                                 ptrace_list);
1559                                 if (!eligible_child(pid, options, p))
1560                                         continue;
1561                                 flag = 1;
1562                                 break;
1563                         }
1564                 }
1565                 if (options & __WNOTHREAD)
1566                         break;
1567                 tsk = next_thread(tsk);
1568                 BUG_ON(tsk->signal != current->signal);
1569         } while (tsk != current);
1570
1571         read_unlock(&tasklist_lock);
1572         if (flag) {
1573                 retval = 0;
1574                 if (options & WNOHANG)
1575                         goto end;
1576                 retval = -ERESTARTSYS;
1577                 if (signal_pending(current))
1578                         goto end;
1579                 schedule();
1580                 goto repeat;
1581         }
1582         retval = -ECHILD;
1583         if (unlikely(denied) && !allowed)
1584                 retval = denied;
1585 end:
1586         current->state = TASK_RUNNING;
1587         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1588         if (infop) {
1589                 if (retval > 0)
1590                 retval = 0;
1591                 else {
1592                         /*
1593                          * For a WNOHANG return, clear out all the fields
1594                          * we would set so the user can easily tell the
1595                          * difference.
1596                          */
1597                         if (!retval)
1598                                 retval = put_user(0, &infop->si_signo);
1599                         if (!retval)
1600                                 retval = put_user(0, &infop->si_errno);
1601                         if (!retval)
1602                                 retval = put_user(0, &infop->si_code);
1603                         if (!retval)
1604                                 retval = put_user(0, &infop->si_pid);
1605                         if (!retval)
1606                                 retval = put_user(0, &infop->si_uid);
1607                         if (!retval)
1608                                 retval = put_user(0, &infop->si_status);
1609                 }
1610         }
1611         return retval;
1612 }
1613
1614 asmlinkage long sys_waitid(int which, pid_t pid,
1615                            struct siginfo __user *infop, int options,
1616                            struct rusage __user *ru)
1617 {
1618         long ret;
1619
1620         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1621                 return -EINVAL;
1622         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1623                 return -EINVAL;
1624
1625         switch (which) {
1626         case P_ALL:
1627                 pid = -1;
1628                 break;
1629         case P_PID:
1630                 if (pid <= 0)
1631                         return -EINVAL;
1632                 break;
1633         case P_PGID:
1634                 if (pid <= 0)
1635                         return -EINVAL;
1636                 pid = -pid;
1637                 break;
1638         default:
1639                 return -EINVAL;
1640         }
1641
1642         ret = do_wait(pid, options, infop, NULL, ru);
1643
1644         /* avoid REGPARM breakage on x86: */
1645         prevent_tail_call(ret);
1646         return ret;
1647 }
1648
1649 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1650                           int options, struct rusage __user *ru)
1651 {
1652         long ret;
1653
1654         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1655                         __WNOTHREAD|__WCLONE|__WALL))
1656                 return -EINVAL;
1657         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1658
1659         /* avoid REGPARM breakage on x86: */
1660         prevent_tail_call(ret);
1661         return ret;
1662 }
1663
1664 #ifdef __ARCH_WANT_SYS_WAITPID
1665
1666 /*
1667  * sys_waitpid() remains for compatibility. waitpid() should be
1668  * implemented by calling sys_wait4() from libc.a.
1669  */
1670 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1671 {
1672         return sys_wait4(pid, stat_addr, options, NULL);
1673 }
1674
1675 #endif