Merge git://oss.sgi.com:8090/oss/git/xfs-2.6
[linux-2.6] / kernel / exit.c
1 /*
2  *  linux/kernel/exit.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6
7 #include <linux/config.h>
8 #include <linux/mm.h>
9 #include <linux/slab.h>
10 #include <linux/interrupt.h>
11 #include <linux/smp_lock.h>
12 #include <linux/module.h>
13 #include <linux/capability.h>
14 #include <linux/completion.h>
15 #include <linux/personality.h>
16 #include <linux/tty.h>
17 #include <linux/namespace.h>
18 #include <linux/key.h>
19 #include <linux/security.h>
20 #include <linux/cpu.h>
21 #include <linux/acct.h>
22 #include <linux/file.h>
23 #include <linux/binfmts.h>
24 #include <linux/ptrace.h>
25 #include <linux/profile.h>
26 #include <linux/mount.h>
27 #include <linux/proc_fs.h>
28 #include <linux/mempolicy.h>
29 #include <linux/cpuset.h>
30 #include <linux/syscalls.h>
31 #include <linux/signal.h>
32 #include <linux/posix-timers.h>
33 #include <linux/cn_proc.h>
34 #include <linux/mutex.h>
35 #include <linux/futex.h>
36 #include <linux/compat.h>
37
38 #include <asm/uaccess.h>
39 #include <asm/unistd.h>
40 #include <asm/pgtable.h>
41 #include <asm/mmu_context.h>
42
43 extern void sem_exit (void);
44 extern struct task_struct *child_reaper;
45
46 int getrusage(struct task_struct *, int, struct rusage __user *);
47
48 static void exit_mm(struct task_struct * tsk);
49
50 static void __unhash_process(struct task_struct *p)
51 {
52         nr_threads--;
53         detach_pid(p, PIDTYPE_PID);
54         if (thread_group_leader(p)) {
55                 detach_pid(p, PIDTYPE_PGID);
56                 detach_pid(p, PIDTYPE_SID);
57
58                 list_del_init(&p->tasks);
59                 __get_cpu_var(process_counts)--;
60         }
61         list_del_rcu(&p->thread_group);
62         remove_parent(p);
63 }
64
65 /*
66  * This function expects the tasklist_lock write-locked.
67  */
68 static void __exit_signal(struct task_struct *tsk)
69 {
70         struct signal_struct *sig = tsk->signal;
71         struct sighand_struct *sighand;
72
73         BUG_ON(!sig);
74         BUG_ON(!atomic_read(&sig->count));
75
76         rcu_read_lock();
77         sighand = rcu_dereference(tsk->sighand);
78         spin_lock(&sighand->siglock);
79
80         posix_cpu_timers_exit(tsk);
81         if (atomic_dec_and_test(&sig->count))
82                 posix_cpu_timers_exit_group(tsk);
83         else {
84                 /*
85                  * If there is any task waiting for the group exit
86                  * then notify it:
87                  */
88                 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
89                         wake_up_process(sig->group_exit_task);
90                         sig->group_exit_task = NULL;
91                 }
92                 if (tsk == sig->curr_target)
93                         sig->curr_target = next_thread(tsk);
94                 /*
95                  * Accumulate here the counters for all threads but the
96                  * group leader as they die, so they can be added into
97                  * the process-wide totals when those are taken.
98                  * The group leader stays around as a zombie as long
99                  * as there are other threads.  When it gets reaped,
100                  * the exit.c code will add its counts into these totals.
101                  * We won't ever get here for the group leader, since it
102                  * will have been the last reference on the signal_struct.
103                  */
104                 sig->utime = cputime_add(sig->utime, tsk->utime);
105                 sig->stime = cputime_add(sig->stime, tsk->stime);
106                 sig->min_flt += tsk->min_flt;
107                 sig->maj_flt += tsk->maj_flt;
108                 sig->nvcsw += tsk->nvcsw;
109                 sig->nivcsw += tsk->nivcsw;
110                 sig->sched_time += tsk->sched_time;
111                 sig = NULL; /* Marker for below. */
112         }
113
114         __unhash_process(tsk);
115
116         tsk->signal = NULL;
117         tsk->sighand = NULL;
118         spin_unlock(&sighand->siglock);
119         rcu_read_unlock();
120
121         __cleanup_sighand(sighand);
122         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
123         flush_sigqueue(&tsk->pending);
124         if (sig) {
125                 flush_sigqueue(&sig->shared_pending);
126                 __cleanup_signal(sig);
127         }
128 }
129
130 static void delayed_put_task_struct(struct rcu_head *rhp)
131 {
132         put_task_struct(container_of(rhp, struct task_struct, rcu));
133 }
134
135 void release_task(struct task_struct * p)
136 {
137         int zap_leader;
138         task_t *leader;
139         struct dentry *proc_dentry;
140
141 repeat:
142         atomic_dec(&p->user->processes);
143         spin_lock(&p->proc_lock);
144         proc_dentry = proc_pid_unhash(p);
145         write_lock_irq(&tasklist_lock);
146         ptrace_unlink(p);
147         BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
148         __exit_signal(p);
149
150         /*
151          * If we are the last non-leader member of the thread
152          * group, and the leader is zombie, then notify the
153          * group leader's parent process. (if it wants notification.)
154          */
155         zap_leader = 0;
156         leader = p->group_leader;
157         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
158                 BUG_ON(leader->exit_signal == -1);
159                 do_notify_parent(leader, leader->exit_signal);
160                 /*
161                  * If we were the last child thread and the leader has
162                  * exited already, and the leader's parent ignores SIGCHLD,
163                  * then we are the one who should release the leader.
164                  *
165                  * do_notify_parent() will have marked it self-reaping in
166                  * that case.
167                  */
168                 zap_leader = (leader->exit_signal == -1);
169         }
170
171         sched_exit(p);
172         write_unlock_irq(&tasklist_lock);
173         spin_unlock(&p->proc_lock);
174         proc_pid_flush(proc_dentry);
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, task_t *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                                 || p->real_parent->pid == 1)
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
256                 /* If p is stopped by a debugger on a signal that won't
257                    stop it, then don't count p as stopped.  This isn't
258                    perfect but it's a good approximation.  */
259                 if (unlikely (p->ptrace)
260                     && p->exit_code != SIGSTOP
261                     && p->exit_code != SIGTSTP
262                     && p->exit_code != SIGTTOU
263                     && p->exit_code != SIGTTIN)
264                         continue;
265
266                 retval = 1;
267                 break;
268         } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
269         return retval;
270 }
271
272 /**
273  * reparent_to_init - Reparent the calling kernel thread to the init task.
274  *
275  * If a kernel thread is launched as a result of a system call, or if
276  * it ever exits, it should generally reparent itself to init so that
277  * it is correctly cleaned up on exit.
278  *
279  * The various task state such as scheduling policy and priority may have
280  * been inherited from a user process, so we reset them to sane values here.
281  *
282  * NOTE that reparent_to_init() gives the caller full capabilities.
283  */
284 static void reparent_to_init(void)
285 {
286         write_lock_irq(&tasklist_lock);
287
288         ptrace_unlink(current);
289         /* Reparent to init */
290         remove_parent(current);
291         current->parent = child_reaper;
292         current->real_parent = child_reaper;
293         add_parent(current);
294
295         /* Set the exit signal to SIGCHLD so we signal init on exit */
296         current->exit_signal = SIGCHLD;
297
298         if ((current->policy == SCHED_NORMAL ||
299                         current->policy == SCHED_BATCH)
300                                 && (task_nice(current) < 0))
301                 set_user_nice(current, 0);
302         /* cpus_allowed? */
303         /* rt_priority? */
304         /* signals? */
305         security_task_reparent_to_init(current);
306         memcpy(current->signal->rlim, init_task.signal->rlim,
307                sizeof(current->signal->rlim));
308         atomic_inc(&(INIT_USER->__count));
309         write_unlock_irq(&tasklist_lock);
310         switch_uid(INIT_USER);
311 }
312
313 void __set_special_pids(pid_t session, pid_t pgrp)
314 {
315         struct task_struct *curr = current->group_leader;
316
317         if (curr->signal->session != session) {
318                 detach_pid(curr, PIDTYPE_SID);
319                 curr->signal->session = session;
320                 attach_pid(curr, PIDTYPE_SID, session);
321         }
322         if (process_group(curr) != pgrp) {
323                 detach_pid(curr, PIDTYPE_PGID);
324                 curr->signal->pgrp = pgrp;
325                 attach_pid(curr, PIDTYPE_PGID, pgrp);
326         }
327 }
328
329 void set_special_pids(pid_t session, pid_t pgrp)
330 {
331         write_lock_irq(&tasklist_lock);
332         __set_special_pids(session, pgrp);
333         write_unlock_irq(&tasklist_lock);
334 }
335
336 /*
337  * Let kernel threads use this to say that they
338  * allow a certain signal (since daemonize() will
339  * have disabled all of them by default).
340  */
341 int allow_signal(int sig)
342 {
343         if (!valid_signal(sig) || sig < 1)
344                 return -EINVAL;
345
346         spin_lock_irq(&current->sighand->siglock);
347         sigdelset(&current->blocked, sig);
348         if (!current->mm) {
349                 /* Kernel threads handle their own signals.
350                    Let the signal code know it'll be handled, so
351                    that they don't get converted to SIGKILL or
352                    just silently dropped */
353                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
354         }
355         recalc_sigpending();
356         spin_unlock_irq(&current->sighand->siglock);
357         return 0;
358 }
359
360 EXPORT_SYMBOL(allow_signal);
361
362 int disallow_signal(int sig)
363 {
364         if (!valid_signal(sig) || sig < 1)
365                 return -EINVAL;
366
367         spin_lock_irq(&current->sighand->siglock);
368         sigaddset(&current->blocked, sig);
369         recalc_sigpending();
370         spin_unlock_irq(&current->sighand->siglock);
371         return 0;
372 }
373
374 EXPORT_SYMBOL(disallow_signal);
375
376 /*
377  *      Put all the gunge required to become a kernel thread without
378  *      attached user resources in one place where it belongs.
379  */
380
381 void daemonize(const char *name, ...)
382 {
383         va_list args;
384         struct fs_struct *fs;
385         sigset_t blocked;
386
387         va_start(args, name);
388         vsnprintf(current->comm, sizeof(current->comm), name, args);
389         va_end(args);
390
391         /*
392          * If we were started as result of loading a module, close all of the
393          * user space pages.  We don't need them, and if we didn't close them
394          * they would be locked into memory.
395          */
396         exit_mm(current);
397
398         set_special_pids(1, 1);
399         mutex_lock(&tty_mutex);
400         current->signal->tty = NULL;
401         mutex_unlock(&tty_mutex);
402
403         /* Block and flush all signals */
404         sigfillset(&blocked);
405         sigprocmask(SIG_BLOCK, &blocked, NULL);
406         flush_signals(current);
407
408         /* Become as one with the init task */
409
410         exit_fs(current);       /* current->fs->count--; */
411         fs = init_task.fs;
412         current->fs = fs;
413         atomic_inc(&fs->count);
414         exit_namespace(current);
415         current->namespace = init_task.namespace;
416         get_namespace(current->namespace);
417         exit_files(current);
418         current->files = init_task.files;
419         atomic_inc(&current->files->count);
420
421         reparent_to_init();
422 }
423
424 EXPORT_SYMBOL(daemonize);
425
426 static void close_files(struct files_struct * files)
427 {
428         int i, j;
429         struct fdtable *fdt;
430
431         j = 0;
432
433         /*
434          * It is safe to dereference the fd table without RCU or
435          * ->file_lock because this is the last reference to the
436          * files structure.
437          */
438         fdt = files_fdtable(files);
439         for (;;) {
440                 unsigned long set;
441                 i = j * __NFDBITS;
442                 if (i >= fdt->max_fdset || i >= fdt->max_fds)
443                         break;
444                 set = fdt->open_fds->fds_bits[j++];
445                 while (set) {
446                         if (set & 1) {
447                                 struct file * file = xchg(&fdt->fd[i], NULL);
448                                 if (file)
449                                         filp_close(file, files);
450                         }
451                         i++;
452                         set >>= 1;
453                 }
454         }
455 }
456
457 struct files_struct *get_files_struct(struct task_struct *task)
458 {
459         struct files_struct *files;
460
461         task_lock(task);
462         files = task->files;
463         if (files)
464                 atomic_inc(&files->count);
465         task_unlock(task);
466
467         return files;
468 }
469
470 void fastcall put_files_struct(struct files_struct *files)
471 {
472         struct fdtable *fdt;
473
474         if (atomic_dec_and_test(&files->count)) {
475                 close_files(files);
476                 /*
477                  * Free the fd and fdset arrays if we expanded them.
478                  * If the fdtable was embedded, pass files for freeing
479                  * at the end of the RCU grace period. Otherwise,
480                  * you can free files immediately.
481                  */
482                 fdt = files_fdtable(files);
483                 if (fdt == &files->fdtab)
484                         fdt->free_files = files;
485                 else
486                         kmem_cache_free(files_cachep, files);
487                 free_fdtable(fdt);
488         }
489 }
490
491 EXPORT_SYMBOL(put_files_struct);
492
493 static inline void __exit_files(struct task_struct *tsk)
494 {
495         struct files_struct * files = tsk->files;
496
497         if (files) {
498                 task_lock(tsk);
499                 tsk->files = NULL;
500                 task_unlock(tsk);
501                 put_files_struct(files);
502         }
503 }
504
505 void exit_files(struct task_struct *tsk)
506 {
507         __exit_files(tsk);
508 }
509
510 static inline void __put_fs_struct(struct fs_struct *fs)
511 {
512         /* No need to hold fs->lock if we are killing it */
513         if (atomic_dec_and_test(&fs->count)) {
514                 dput(fs->root);
515                 mntput(fs->rootmnt);
516                 dput(fs->pwd);
517                 mntput(fs->pwdmnt);
518                 if (fs->altroot) {
519                         dput(fs->altroot);
520                         mntput(fs->altrootmnt);
521                 }
522                 kmem_cache_free(fs_cachep, fs);
523         }
524 }
525
526 void put_fs_struct(struct fs_struct *fs)
527 {
528         __put_fs_struct(fs);
529 }
530
531 static inline void __exit_fs(struct task_struct *tsk)
532 {
533         struct fs_struct * fs = tsk->fs;
534
535         if (fs) {
536                 task_lock(tsk);
537                 tsk->fs = NULL;
538                 task_unlock(tsk);
539                 __put_fs_struct(fs);
540         }
541 }
542
543 void exit_fs(struct task_struct *tsk)
544 {
545         __exit_fs(tsk);
546 }
547
548 EXPORT_SYMBOL_GPL(exit_fs);
549
550 /*
551  * Turn us into a lazy TLB process if we
552  * aren't already..
553  */
554 static void exit_mm(struct task_struct * tsk)
555 {
556         struct mm_struct *mm = tsk->mm;
557
558         mm_release(tsk, mm);
559         if (!mm)
560                 return;
561         /*
562          * Serialize with any possible pending coredump.
563          * We must hold mmap_sem around checking core_waiters
564          * and clearing tsk->mm.  The core-inducing thread
565          * will increment core_waiters for each thread in the
566          * group with ->mm != NULL.
567          */
568         down_read(&mm->mmap_sem);
569         if (mm->core_waiters) {
570                 up_read(&mm->mmap_sem);
571                 down_write(&mm->mmap_sem);
572                 if (!--mm->core_waiters)
573                         complete(mm->core_startup_done);
574                 up_write(&mm->mmap_sem);
575
576                 wait_for_completion(&mm->core_done);
577                 down_read(&mm->mmap_sem);
578         }
579         atomic_inc(&mm->mm_count);
580         if (mm != tsk->active_mm) BUG();
581         /* more a memory barrier than a real lock */
582         task_lock(tsk);
583         tsk->mm = NULL;
584         up_read(&mm->mmap_sem);
585         enter_lazy_tlb(mm, current);
586         task_unlock(tsk);
587         mmput(mm);
588 }
589
590 static inline void choose_new_parent(task_t *p, task_t *reaper)
591 {
592         /*
593          * Make sure we're not reparenting to ourselves and that
594          * the parent is not a zombie.
595          */
596         BUG_ON(p == reaper || reaper->exit_state);
597         p->real_parent = reaper;
598 }
599
600 static void reparent_thread(task_t *p, task_t *father, int traced)
601 {
602         /* We don't want people slaying init.  */
603         if (p->exit_signal != -1)
604                 p->exit_signal = SIGCHLD;
605
606         if (p->pdeath_signal)
607                 /* We already hold the tasklist_lock here.  */
608                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
609
610         /* Move the child from its dying parent to the new one.  */
611         if (unlikely(traced)) {
612                 /* Preserve ptrace links if someone else is tracing this child.  */
613                 list_del_init(&p->ptrace_list);
614                 if (p->parent != p->real_parent)
615                         list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
616         } else {
617                 /* If this child is being traced, then we're the one tracing it
618                  * anyway, so let go of it.
619                  */
620                 p->ptrace = 0;
621                 remove_parent(p);
622                 p->parent = p->real_parent;
623                 add_parent(p);
624
625                 /* If we'd notified the old parent about this child's death,
626                  * also notify the new parent.
627                  */
628                 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
629                     thread_group_empty(p))
630                         do_notify_parent(p, p->exit_signal);
631                 else if (p->state == TASK_TRACED) {
632                         /*
633                          * If it was at a trace stop, turn it into
634                          * a normal stop since it's no longer being
635                          * traced.
636                          */
637                         ptrace_untrace(p);
638                 }
639         }
640
641         /*
642          * process group orphan check
643          * Case ii: Our child is in a different pgrp
644          * than we are, and it was the only connection
645          * outside, so the child pgrp is now orphaned.
646          */
647         if ((process_group(p) != process_group(father)) &&
648             (p->signal->session == father->signal->session)) {
649                 int pgrp = process_group(p);
650
651                 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
652                         __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
653                         __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
654                 }
655         }
656 }
657
658 /*
659  * When we die, we re-parent all our children.
660  * Try to give them to another thread in our thread
661  * group, and if no such member exists, give it to
662  * the global child reaper process (ie "init")
663  */
664 static void forget_original_parent(struct task_struct * father,
665                                           struct list_head *to_release)
666 {
667         struct task_struct *p, *reaper = father;
668         struct list_head *_p, *_n;
669
670         do {
671                 reaper = next_thread(reaper);
672                 if (reaper == father) {
673                         reaper = child_reaper;
674                         break;
675                 }
676         } while (reaper->exit_state);
677
678         /*
679          * There are only two places where our children can be:
680          *
681          * - in our child list
682          * - in our ptraced child list
683          *
684          * Search them and reparent children.
685          */
686         list_for_each_safe(_p, _n, &father->children) {
687                 int ptrace;
688                 p = list_entry(_p,struct task_struct,sibling);
689
690                 ptrace = p->ptrace;
691
692                 /* if father isn't the real parent, then ptrace must be enabled */
693                 BUG_ON(father != p->real_parent && !ptrace);
694
695                 if (father == p->real_parent) {
696                         /* reparent with a reaper, real father it's us */
697                         choose_new_parent(p, reaper);
698                         reparent_thread(p, father, 0);
699                 } else {
700                         /* reparent ptraced task to its real parent */
701                         __ptrace_unlink (p);
702                         if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
703                             thread_group_empty(p))
704                                 do_notify_parent(p, p->exit_signal);
705                 }
706
707                 /*
708                  * if the ptraced child is a zombie with exit_signal == -1
709                  * we must collect it before we exit, or it will remain
710                  * zombie forever since we prevented it from self-reap itself
711                  * while it was being traced by us, to be able to see it in wait4.
712                  */
713                 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
714                         list_add(&p->ptrace_list, to_release);
715         }
716         list_for_each_safe(_p, _n, &father->ptrace_children) {
717                 p = list_entry(_p,struct task_struct,ptrace_list);
718                 choose_new_parent(p, reaper);
719                 reparent_thread(p, father, 1);
720         }
721 }
722
723 /*
724  * Send signals to all our closest relatives so that they know
725  * to properly mourn us..
726  */
727 static void exit_notify(struct task_struct *tsk)
728 {
729         int state;
730         struct task_struct *t;
731         struct list_head ptrace_dead, *_p, *_n;
732
733         if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
734             && !thread_group_empty(tsk)) {
735                 /*
736                  * This occurs when there was a race between our exit
737                  * syscall and a group signal choosing us as the one to
738                  * wake up.  It could be that we are the only thread
739                  * alerted to check for pending signals, but another thread
740                  * should be woken now to take the signal since we will not.
741                  * Now we'll wake all the threads in the group just to make
742                  * sure someone gets all the pending signals.
743                  */
744                 read_lock(&tasklist_lock);
745                 spin_lock_irq(&tsk->sighand->siglock);
746                 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
747                         if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
748                                 recalc_sigpending_tsk(t);
749                                 if (signal_pending(t))
750                                         signal_wake_up(t, 0);
751                         }
752                 spin_unlock_irq(&tsk->sighand->siglock);
753                 read_unlock(&tasklist_lock);
754         }
755
756         write_lock_irq(&tasklist_lock);
757
758         /*
759          * This does two things:
760          *
761          * A.  Make init inherit all the child processes
762          * B.  Check to see if any process groups have become orphaned
763          *      as a result of our exiting, and if they have any stopped
764          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
765          */
766
767         INIT_LIST_HEAD(&ptrace_dead);
768         forget_original_parent(tsk, &ptrace_dead);
769         BUG_ON(!list_empty(&tsk->children));
770         BUG_ON(!list_empty(&tsk->ptrace_children));
771
772         /*
773          * Check to see if any process groups have become orphaned
774          * as a result of our exiting, and if they have any stopped
775          * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
776          *
777          * Case i: Our father is in a different pgrp than we are
778          * and we were the only connection outside, so our pgrp
779          * is about to become orphaned.
780          */
781          
782         t = tsk->real_parent;
783         
784         if ((process_group(t) != process_group(tsk)) &&
785             (t->signal->session == tsk->signal->session) &&
786             will_become_orphaned_pgrp(process_group(tsk), tsk) &&
787             has_stopped_jobs(process_group(tsk))) {
788                 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
789                 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
790         }
791
792         /* Let father know we died 
793          *
794          * Thread signals are configurable, but you aren't going to use
795          * that to send signals to arbitary processes. 
796          * That stops right now.
797          *
798          * If the parent exec id doesn't match the exec id we saved
799          * when we started then we know the parent has changed security
800          * domain.
801          *
802          * If our self_exec id doesn't match our parent_exec_id then
803          * we have changed execution domain as these two values started
804          * the same after a fork.
805          *      
806          */
807         
808         if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
809             ( tsk->parent_exec_id != t->self_exec_id  ||
810               tsk->self_exec_id != tsk->parent_exec_id)
811             && !capable(CAP_KILL))
812                 tsk->exit_signal = SIGCHLD;
813
814
815         /* If something other than our normal parent is ptracing us, then
816          * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
817          * only has special meaning to our real parent.
818          */
819         if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
820                 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
821                 do_notify_parent(tsk, signal);
822         } else if (tsk->ptrace) {
823                 do_notify_parent(tsk, SIGCHLD);
824         }
825
826         state = EXIT_ZOMBIE;
827         if (tsk->exit_signal == -1 &&
828             (likely(tsk->ptrace == 0) ||
829              unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
830                 state = EXIT_DEAD;
831         tsk->exit_state = state;
832
833         write_unlock_irq(&tasklist_lock);
834
835         list_for_each_safe(_p, _n, &ptrace_dead) {
836                 list_del_init(_p);
837                 t = list_entry(_p,struct task_struct,ptrace_list);
838                 release_task(t);
839         }
840
841         /* If the process is dead, release it - nobody will wait for it */
842         if (state == EXIT_DEAD)
843                 release_task(tsk);
844 }
845
846 fastcall NORET_TYPE void do_exit(long code)
847 {
848         struct task_struct *tsk = current;
849         int group_dead;
850
851         profile_task_exit(tsk);
852
853         WARN_ON(atomic_read(&tsk->fs_excl));
854
855         if (unlikely(in_interrupt()))
856                 panic("Aiee, killing interrupt handler!");
857         if (unlikely(!tsk->pid))
858                 panic("Attempted to kill the idle task!");
859         if (unlikely(tsk == child_reaper))
860                 panic("Attempted to kill init!");
861
862         if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
863                 current->ptrace_message = code;
864                 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
865         }
866
867         /*
868          * We're taking recursive faults here in do_exit. Safest is to just
869          * leave this task alone and wait for reboot.
870          */
871         if (unlikely(tsk->flags & PF_EXITING)) {
872                 printk(KERN_ALERT
873                         "Fixing recursive fault but reboot is needed!\n");
874                 if (tsk->io_context)
875                         exit_io_context();
876                 set_current_state(TASK_UNINTERRUPTIBLE);
877                 schedule();
878         }
879
880         tsk->flags |= PF_EXITING;
881
882         /*
883          * Make sure we don't try to process any timer firings
884          * while we are already exiting.
885          */
886         tsk->it_virt_expires = cputime_zero;
887         tsk->it_prof_expires = cputime_zero;
888         tsk->it_sched_expires = 0;
889
890         if (unlikely(in_atomic()))
891                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
892                                 current->comm, current->pid,
893                                 preempt_count());
894
895         acct_update_integrals(tsk);
896         if (tsk->mm) {
897                 update_hiwater_rss(tsk->mm);
898                 update_hiwater_vm(tsk->mm);
899         }
900         group_dead = atomic_dec_and_test(&tsk->signal->live);
901         if (group_dead) {
902                 hrtimer_cancel(&tsk->signal->real_timer);
903                 exit_itimers(tsk->signal);
904                 acct_process(code);
905         }
906         if (unlikely(tsk->robust_list))
907                 exit_robust_list(tsk);
908 #ifdef CONFIG_COMPAT
909         if (unlikely(tsk->compat_robust_list))
910                 compat_exit_robust_list(tsk);
911 #endif
912         exit_mm(tsk);
913
914         exit_sem(tsk);
915         __exit_files(tsk);
916         __exit_fs(tsk);
917         exit_namespace(tsk);
918         exit_thread();
919         cpuset_exit(tsk);
920         exit_keys(tsk);
921
922         if (group_dead && tsk->signal->leader)
923                 disassociate_ctty(1);
924
925         module_put(task_thread_info(tsk)->exec_domain->module);
926         if (tsk->binfmt)
927                 module_put(tsk->binfmt->module);
928
929         tsk->exit_code = code;
930         proc_exit_connector(tsk);
931         exit_notify(tsk);
932 #ifdef CONFIG_NUMA
933         mpol_free(tsk->mempolicy);
934         tsk->mempolicy = NULL;
935 #endif
936         /*
937          * If DEBUG_MUTEXES is on, make sure we are holding no locks:
938          */
939         mutex_debug_check_no_locks_held(tsk);
940
941         if (tsk->io_context)
942                 exit_io_context();
943
944         /* PF_DEAD causes final put_task_struct after we schedule. */
945         preempt_disable();
946         BUG_ON(tsk->flags & PF_DEAD);
947         tsk->flags |= PF_DEAD;
948
949         schedule();
950         BUG();
951         /* Avoid "noreturn function does return".  */
952         for (;;) ;
953 }
954
955 EXPORT_SYMBOL_GPL(do_exit);
956
957 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
958 {
959         if (comp)
960                 complete(comp);
961         
962         do_exit(code);
963 }
964
965 EXPORT_SYMBOL(complete_and_exit);
966
967 asmlinkage long sys_exit(int error_code)
968 {
969         do_exit((error_code&0xff)<<8);
970 }
971
972 /*
973  * Take down every thread in the group.  This is called by fatal signals
974  * as well as by sys_exit_group (below).
975  */
976 NORET_TYPE void
977 do_group_exit(int exit_code)
978 {
979         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
980
981         if (current->signal->flags & SIGNAL_GROUP_EXIT)
982                 exit_code = current->signal->group_exit_code;
983         else if (!thread_group_empty(current)) {
984                 struct signal_struct *const sig = current->signal;
985                 struct sighand_struct *const sighand = current->sighand;
986                 spin_lock_irq(&sighand->siglock);
987                 if (sig->flags & SIGNAL_GROUP_EXIT)
988                         /* Another thread got here before we took the lock.  */
989                         exit_code = sig->group_exit_code;
990                 else {
991                         sig->group_exit_code = exit_code;
992                         zap_other_threads(current);
993                 }
994                 spin_unlock_irq(&sighand->siglock);
995         }
996
997         do_exit(exit_code);
998         /* NOTREACHED */
999 }
1000
1001 /*
1002  * this kills every thread in the thread group. Note that any externally
1003  * wait4()-ing process will get the correct exit code - even if this
1004  * thread is not the thread group leader.
1005  */
1006 asmlinkage void sys_exit_group(int error_code)
1007 {
1008         do_group_exit((error_code & 0xff) << 8);
1009 }
1010
1011 static int eligible_child(pid_t pid, int options, task_t *p)
1012 {
1013         if (pid > 0) {
1014                 if (p->pid != pid)
1015                         return 0;
1016         } else if (!pid) {
1017                 if (process_group(p) != process_group(current))
1018                         return 0;
1019         } else if (pid != -1) {
1020                 if (process_group(p) != -pid)
1021                         return 0;
1022         }
1023
1024         /*
1025          * Do not consider detached threads that are
1026          * not ptraced:
1027          */
1028         if (p->exit_signal == -1 && !p->ptrace)
1029                 return 0;
1030
1031         /* Wait for all children (clone and not) if __WALL is set;
1032          * otherwise, wait for clone children *only* if __WCLONE is
1033          * set; otherwise, wait for non-clone children *only*.  (Note:
1034          * A "clone" child here is one that reports to its parent
1035          * using a signal other than SIGCHLD.) */
1036         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1037             && !(options & __WALL))
1038                 return 0;
1039         /*
1040          * Do not consider thread group leaders that are
1041          * in a non-empty thread group:
1042          */
1043         if (current->tgid != p->tgid && delay_group_leader(p))
1044                 return 2;
1045
1046         if (security_task_wait(p))
1047                 return 0;
1048
1049         return 1;
1050 }
1051
1052 static int wait_noreap_copyout(task_t *p, pid_t pid, uid_t uid,
1053                                int why, int status,
1054                                struct siginfo __user *infop,
1055                                struct rusage __user *rusagep)
1056 {
1057         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1058         put_task_struct(p);
1059         if (!retval)
1060                 retval = put_user(SIGCHLD, &infop->si_signo);
1061         if (!retval)
1062                 retval = put_user(0, &infop->si_errno);
1063         if (!retval)
1064                 retval = put_user((short)why, &infop->si_code);
1065         if (!retval)
1066                 retval = put_user(pid, &infop->si_pid);
1067         if (!retval)
1068                 retval = put_user(uid, &infop->si_uid);
1069         if (!retval)
1070                 retval = put_user(status, &infop->si_status);
1071         if (!retval)
1072                 retval = pid;
1073         return retval;
1074 }
1075
1076 /*
1077  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1078  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1079  * the lock and this task is uninteresting.  If we return nonzero, we have
1080  * released the lock and the system call should return.
1081  */
1082 static int wait_task_zombie(task_t *p, int noreap,
1083                             struct siginfo __user *infop,
1084                             int __user *stat_addr, struct rusage __user *ru)
1085 {
1086         unsigned long state;
1087         int retval;
1088         int status;
1089
1090         if (unlikely(noreap)) {
1091                 pid_t pid = p->pid;
1092                 uid_t uid = p->uid;
1093                 int exit_code = p->exit_code;
1094                 int why, status;
1095
1096                 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1097                         return 0;
1098                 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1099                         return 0;
1100                 get_task_struct(p);
1101                 read_unlock(&tasklist_lock);
1102                 if ((exit_code & 0x7f) == 0) {
1103                         why = CLD_EXITED;
1104                         status = exit_code >> 8;
1105                 } else {
1106                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1107                         status = exit_code & 0x7f;
1108                 }
1109                 return wait_noreap_copyout(p, pid, uid, why,
1110                                            status, infop, ru);
1111         }
1112
1113         /*
1114          * Try to move the task's state to DEAD
1115          * only one thread is allowed to do this:
1116          */
1117         state = xchg(&p->exit_state, EXIT_DEAD);
1118         if (state != EXIT_ZOMBIE) {
1119                 BUG_ON(state != EXIT_DEAD);
1120                 return 0;
1121         }
1122         if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1123                 /*
1124                  * This can only happen in a race with a ptraced thread
1125                  * dying on another processor.
1126                  */
1127                 return 0;
1128         }
1129
1130         if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1131                 struct signal_struct *psig;
1132                 struct signal_struct *sig;
1133
1134                 /*
1135                  * The resource counters for the group leader are in its
1136                  * own task_struct.  Those for dead threads in the group
1137                  * are in its signal_struct, as are those for the child
1138                  * processes it has previously reaped.  All these
1139                  * accumulate in the parent's signal_struct c* fields.
1140                  *
1141                  * We don't bother to take a lock here to protect these
1142                  * p->signal fields, because they are only touched by
1143                  * __exit_signal, which runs with tasklist_lock
1144                  * write-locked anyway, and so is excluded here.  We do
1145                  * need to protect the access to p->parent->signal fields,
1146                  * as other threads in the parent group can be right
1147                  * here reaping other children at the same time.
1148                  */
1149                 spin_lock_irq(&p->parent->sighand->siglock);
1150                 psig = p->parent->signal;
1151                 sig = p->signal;
1152                 psig->cutime =
1153                         cputime_add(psig->cutime,
1154                         cputime_add(p->utime,
1155                         cputime_add(sig->utime,
1156                                     sig->cutime)));
1157                 psig->cstime =
1158                         cputime_add(psig->cstime,
1159                         cputime_add(p->stime,
1160                         cputime_add(sig->stime,
1161                                     sig->cstime)));
1162                 psig->cmin_flt +=
1163                         p->min_flt + sig->min_flt + sig->cmin_flt;
1164                 psig->cmaj_flt +=
1165                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1166                 psig->cnvcsw +=
1167                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1168                 psig->cnivcsw +=
1169                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1170                 spin_unlock_irq(&p->parent->sighand->siglock);
1171         }
1172
1173         /*
1174          * Now we are sure this task is interesting, and no other
1175          * thread can reap it because we set its state to EXIT_DEAD.
1176          */
1177         read_unlock(&tasklist_lock);
1178
1179         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1180         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1181                 ? p->signal->group_exit_code : p->exit_code;
1182         if (!retval && stat_addr)
1183                 retval = put_user(status, stat_addr);
1184         if (!retval && infop)
1185                 retval = put_user(SIGCHLD, &infop->si_signo);
1186         if (!retval && infop)
1187                 retval = put_user(0, &infop->si_errno);
1188         if (!retval && infop) {
1189                 int why;
1190
1191                 if ((status & 0x7f) == 0) {
1192                         why = CLD_EXITED;
1193                         status >>= 8;
1194                 } else {
1195                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1196                         status &= 0x7f;
1197                 }
1198                 retval = put_user((short)why, &infop->si_code);
1199                 if (!retval)
1200                         retval = put_user(status, &infop->si_status);
1201         }
1202         if (!retval && infop)
1203                 retval = put_user(p->pid, &infop->si_pid);
1204         if (!retval && infop)
1205                 retval = put_user(p->uid, &infop->si_uid);
1206         if (retval) {
1207                 // TODO: is this safe?
1208                 p->exit_state = EXIT_ZOMBIE;
1209                 return retval;
1210         }
1211         retval = p->pid;
1212         if (p->real_parent != p->parent) {
1213                 write_lock_irq(&tasklist_lock);
1214                 /* Double-check with lock held.  */
1215                 if (p->real_parent != p->parent) {
1216                         __ptrace_unlink(p);
1217                         // TODO: is this safe?
1218                         p->exit_state = EXIT_ZOMBIE;
1219                         /*
1220                          * If this is not a detached task, notify the parent.
1221                          * If it's still not detached after that, don't release
1222                          * it now.
1223                          */
1224                         if (p->exit_signal != -1) {
1225                                 do_notify_parent(p, p->exit_signal);
1226                                 if (p->exit_signal != -1)
1227                                         p = NULL;
1228                         }
1229                 }
1230                 write_unlock_irq(&tasklist_lock);
1231         }
1232         if (p != NULL)
1233                 release_task(p);
1234         BUG_ON(!retval);
1235         return retval;
1236 }
1237
1238 /*
1239  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1240  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1241  * the lock and this task is uninteresting.  If we return nonzero, we have
1242  * released the lock and the system call should return.
1243  */
1244 static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap,
1245                              struct siginfo __user *infop,
1246                              int __user *stat_addr, struct rusage __user *ru)
1247 {
1248         int retval, exit_code;
1249
1250         if (!p->exit_code)
1251                 return 0;
1252         if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1253             p->signal && p->signal->group_stop_count > 0)
1254                 /*
1255                  * A group stop is in progress and this is the group leader.
1256                  * We won't report until all threads have stopped.
1257                  */
1258                 return 0;
1259
1260         /*
1261          * Now we are pretty sure this task is interesting.
1262          * Make sure it doesn't get reaped out from under us while we
1263          * give up the lock and then examine it below.  We don't want to
1264          * keep holding onto the tasklist_lock while we call getrusage and
1265          * possibly take page faults for user memory.
1266          */
1267         get_task_struct(p);
1268         read_unlock(&tasklist_lock);
1269
1270         if (unlikely(noreap)) {
1271                 pid_t pid = p->pid;
1272                 uid_t uid = p->uid;
1273                 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1274
1275                 exit_code = p->exit_code;
1276                 if (unlikely(!exit_code) ||
1277                     unlikely(p->state & TASK_TRACED))
1278                         goto bail_ref;
1279                 return wait_noreap_copyout(p, pid, uid,
1280                                            why, (exit_code << 8) | 0x7f,
1281                                            infop, ru);
1282         }
1283
1284         write_lock_irq(&tasklist_lock);
1285
1286         /*
1287          * This uses xchg to be atomic with the thread resuming and setting
1288          * it.  It must also be done with the write lock held to prevent a
1289          * race with the EXIT_ZOMBIE case.
1290          */
1291         exit_code = xchg(&p->exit_code, 0);
1292         if (unlikely(p->exit_state)) {
1293                 /*
1294                  * The task resumed and then died.  Let the next iteration
1295                  * catch it in EXIT_ZOMBIE.  Note that exit_code might
1296                  * already be zero here if it resumed and did _exit(0).
1297                  * The task itself is dead and won't touch exit_code again;
1298                  * other processors in this function are locked out.
1299                  */
1300                 p->exit_code = exit_code;
1301                 exit_code = 0;
1302         }
1303         if (unlikely(exit_code == 0)) {
1304                 /*
1305                  * Another thread in this function got to it first, or it
1306                  * resumed, or it resumed and then died.
1307                  */
1308                 write_unlock_irq(&tasklist_lock);
1309 bail_ref:
1310                 put_task_struct(p);
1311                 /*
1312                  * We are returning to the wait loop without having successfully
1313                  * removed the process and having released the lock. We cannot
1314                  * continue, since the "p" task pointer is potentially stale.
1315                  *
1316                  * Return -EAGAIN, and do_wait() will restart the loop from the
1317                  * beginning. Do _not_ re-acquire the lock.
1318                  */
1319                 return -EAGAIN;
1320         }
1321
1322         /* move to end of parent's list to avoid starvation */
1323         remove_parent(p);
1324         add_parent(p);
1325
1326         write_unlock_irq(&tasklist_lock);
1327
1328         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1329         if (!retval && stat_addr)
1330                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1331         if (!retval && infop)
1332                 retval = put_user(SIGCHLD, &infop->si_signo);
1333         if (!retval && infop)
1334                 retval = put_user(0, &infop->si_errno);
1335         if (!retval && infop)
1336                 retval = put_user((short)((p->ptrace & PT_PTRACED)
1337                                           ? CLD_TRAPPED : CLD_STOPPED),
1338                                   &infop->si_code);
1339         if (!retval && infop)
1340                 retval = put_user(exit_code, &infop->si_status);
1341         if (!retval && infop)
1342                 retval = put_user(p->pid, &infop->si_pid);
1343         if (!retval && infop)
1344                 retval = put_user(p->uid, &infop->si_uid);
1345         if (!retval)
1346                 retval = p->pid;
1347         put_task_struct(p);
1348
1349         BUG_ON(!retval);
1350         return retval;
1351 }
1352
1353 /*
1354  * Handle do_wait work for one task in a live, non-stopped state.
1355  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1356  * the lock and this task is uninteresting.  If we return nonzero, we have
1357  * released the lock and the system call should return.
1358  */
1359 static int wait_task_continued(task_t *p, int noreap,
1360                                struct siginfo __user *infop,
1361                                int __user *stat_addr, struct rusage __user *ru)
1362 {
1363         int retval;
1364         pid_t pid;
1365         uid_t uid;
1366
1367         if (unlikely(!p->signal))
1368                 return 0;
1369
1370         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1371                 return 0;
1372
1373         spin_lock_irq(&p->sighand->siglock);
1374         /* Re-check with the lock held.  */
1375         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1376                 spin_unlock_irq(&p->sighand->siglock);
1377                 return 0;
1378         }
1379         if (!noreap)
1380                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1381         spin_unlock_irq(&p->sighand->siglock);
1382
1383         pid = p->pid;
1384         uid = p->uid;
1385         get_task_struct(p);
1386         read_unlock(&tasklist_lock);
1387
1388         if (!infop) {
1389                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1390                 put_task_struct(p);
1391                 if (!retval && stat_addr)
1392                         retval = put_user(0xffff, stat_addr);
1393                 if (!retval)
1394                         retval = p->pid;
1395         } else {
1396                 retval = wait_noreap_copyout(p, pid, uid,
1397                                              CLD_CONTINUED, SIGCONT,
1398                                              infop, ru);
1399                 BUG_ON(retval == 0);
1400         }
1401
1402         return retval;
1403 }
1404
1405
1406 static inline int my_ptrace_child(struct task_struct *p)
1407 {
1408         if (!(p->ptrace & PT_PTRACED))
1409                 return 0;
1410         if (!(p->ptrace & PT_ATTACHED))
1411                 return 1;
1412         /*
1413          * This child was PTRACE_ATTACH'd.  We should be seeing it only if
1414          * we are the attacher.  If we are the real parent, this is a race
1415          * inside ptrace_attach.  It is waiting for the tasklist_lock,
1416          * which we have to switch the parent links, but has already set
1417          * the flags in p->ptrace.
1418          */
1419         return (p->parent != p->real_parent);
1420 }
1421
1422 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1423                     int __user *stat_addr, struct rusage __user *ru)
1424 {
1425         DECLARE_WAITQUEUE(wait, current);
1426         struct task_struct *tsk;
1427         int flag, retval;
1428
1429         add_wait_queue(&current->signal->wait_chldexit,&wait);
1430 repeat:
1431         /*
1432          * We will set this flag if we see any child that might later
1433          * match our criteria, even if we are not able to reap it yet.
1434          */
1435         flag = 0;
1436         current->state = TASK_INTERRUPTIBLE;
1437         read_lock(&tasklist_lock);
1438         tsk = current;
1439         do {
1440                 struct task_struct *p;
1441                 struct list_head *_p;
1442                 int ret;
1443
1444                 list_for_each(_p,&tsk->children) {
1445                         p = list_entry(_p,struct task_struct,sibling);
1446
1447                         ret = eligible_child(pid, options, p);
1448                         if (!ret)
1449                                 continue;
1450
1451                         switch (p->state) {
1452                         case TASK_TRACED:
1453                                 /*
1454                                  * When we hit the race with PTRACE_ATTACH,
1455                                  * we will not report this child.  But the
1456                                  * race means it has not yet been moved to
1457                                  * our ptrace_children list, so we need to
1458                                  * set the flag here to avoid a spurious ECHILD
1459                                  * when the race happens with the only child.
1460                                  */
1461                                 flag = 1;
1462                                 if (!my_ptrace_child(p))
1463                                         continue;
1464                                 /*FALLTHROUGH*/
1465                         case TASK_STOPPED:
1466                                 /*
1467                                  * It's stopped now, so it might later
1468                                  * continue, exit, or stop again.
1469                                  */
1470                                 flag = 1;
1471                                 if (!(options & WUNTRACED) &&
1472                                     !my_ptrace_child(p))
1473                                         continue;
1474                                 retval = wait_task_stopped(p, ret == 2,
1475                                                            (options & WNOWAIT),
1476                                                            infop,
1477                                                            stat_addr, ru);
1478                                 if (retval == -EAGAIN)
1479                                         goto repeat;
1480                                 if (retval != 0) /* He released the lock.  */
1481                                         goto end;
1482                                 break;
1483                         default:
1484                         // case EXIT_DEAD:
1485                                 if (p->exit_state == EXIT_DEAD)
1486                                         continue;
1487                         // case EXIT_ZOMBIE:
1488                                 if (p->exit_state == EXIT_ZOMBIE) {
1489                                         /*
1490                                          * Eligible but we cannot release
1491                                          * it yet:
1492                                          */
1493                                         if (ret == 2)
1494                                                 goto check_continued;
1495                                         if (!likely(options & WEXITED))
1496                                                 continue;
1497                                         retval = wait_task_zombie(
1498                                                 p, (options & WNOWAIT),
1499                                                 infop, stat_addr, ru);
1500                                         /* He released the lock.  */
1501                                         if (retval != 0)
1502                                                 goto end;
1503                                         break;
1504                                 }
1505 check_continued:
1506                                 /*
1507                                  * It's running now, so it might later
1508                                  * exit, stop, or stop and then continue.
1509                                  */
1510                                 flag = 1;
1511                                 if (!unlikely(options & WCONTINUED))
1512                                         continue;
1513                                 retval = wait_task_continued(
1514                                         p, (options & WNOWAIT),
1515                                         infop, stat_addr, ru);
1516                                 if (retval != 0) /* He released the lock.  */
1517                                         goto end;
1518                                 break;
1519                         }
1520                 }
1521                 if (!flag) {
1522                         list_for_each(_p, &tsk->ptrace_children) {
1523                                 p = list_entry(_p, struct task_struct,
1524                                                 ptrace_list);
1525                                 if (!eligible_child(pid, options, p))
1526                                         continue;
1527                                 flag = 1;
1528                                 break;
1529                         }
1530                 }
1531                 if (options & __WNOTHREAD)
1532                         break;
1533                 tsk = next_thread(tsk);
1534                 if (tsk->signal != current->signal)
1535                         BUG();
1536         } while (tsk != current);
1537
1538         read_unlock(&tasklist_lock);
1539         if (flag) {
1540                 retval = 0;
1541                 if (options & WNOHANG)
1542                         goto end;
1543                 retval = -ERESTARTSYS;
1544                 if (signal_pending(current))
1545                         goto end;
1546                 schedule();
1547                 goto repeat;
1548         }
1549         retval = -ECHILD;
1550 end:
1551         current->state = TASK_RUNNING;
1552         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1553         if (infop) {
1554                 if (retval > 0)
1555                 retval = 0;
1556                 else {
1557                         /*
1558                          * For a WNOHANG return, clear out all the fields
1559                          * we would set so the user can easily tell the
1560                          * difference.
1561                          */
1562                         if (!retval)
1563                                 retval = put_user(0, &infop->si_signo);
1564                         if (!retval)
1565                                 retval = put_user(0, &infop->si_errno);
1566                         if (!retval)
1567                                 retval = put_user(0, &infop->si_code);
1568                         if (!retval)
1569                                 retval = put_user(0, &infop->si_pid);
1570                         if (!retval)
1571                                 retval = put_user(0, &infop->si_uid);
1572                         if (!retval)
1573                                 retval = put_user(0, &infop->si_status);
1574                 }
1575         }
1576         return retval;
1577 }
1578
1579 asmlinkage long sys_waitid(int which, pid_t pid,
1580                            struct siginfo __user *infop, int options,
1581                            struct rusage __user *ru)
1582 {
1583         long ret;
1584
1585         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1586                 return -EINVAL;
1587         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1588                 return -EINVAL;
1589
1590         switch (which) {
1591         case P_ALL:
1592                 pid = -1;
1593                 break;
1594         case P_PID:
1595                 if (pid <= 0)
1596                         return -EINVAL;
1597                 break;
1598         case P_PGID:
1599                 if (pid <= 0)
1600                         return -EINVAL;
1601                 pid = -pid;
1602                 break;
1603         default:
1604                 return -EINVAL;
1605         }
1606
1607         ret = do_wait(pid, options, infop, NULL, ru);
1608
1609         /* avoid REGPARM breakage on x86: */
1610         prevent_tail_call(ret);
1611         return ret;
1612 }
1613
1614 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1615                           int options, struct rusage __user *ru)
1616 {
1617         long ret;
1618
1619         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1620                         __WNOTHREAD|__WCLONE|__WALL))
1621                 return -EINVAL;
1622         ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1623
1624         /* avoid REGPARM breakage on x86: */
1625         prevent_tail_call(ret);
1626         return ret;
1627 }
1628
1629 #ifdef __ARCH_WANT_SYS_WAITPID
1630
1631 /*
1632  * sys_waitpid() remains for compatibility. waitpid() should be
1633  * implemented by calling sys_wait4() from libc.a.
1634  */
1635 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1636 {
1637         return sys_wait4(pid, stat_addr, options, NULL);
1638 }
1639
1640 #endif