Merge branch 'linus' into stackprotector
[linux-2.6.git] / kernel / exit.c
1 /*
2  *  linux/kernel/exit.c
3  *
4  *  Copyright (C) 1991, 1992  Linus Torvalds
5  */
6
7 #include <linux/mm.h>
8 #include <linux/slab.h>
9 #include <linux/interrupt.h>
10 #include <linux/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/iocontext.h>
17 #include <linux/key.h>
18 #include <linux/security.h>
19 #include <linux/cpu.h>
20 #include <linux/acct.h>
21 #include <linux/tsacct_kern.h>
22 #include <linux/file.h>
23 #include <linux/fdtable.h>
24 #include <linux/binfmts.h>
25 #include <linux/nsproxy.h>
26 #include <linux/pid_namespace.h>
27 #include <linux/ptrace.h>
28 #include <linux/profile.h>
29 #include <linux/mount.h>
30 #include <linux/proc_fs.h>
31 #include <linux/kthread.h>
32 #include <linux/mempolicy.h>
33 #include <linux/taskstats_kern.h>
34 #include <linux/delayacct.h>
35 #include <linux/freezer.h>
36 #include <linux/cgroup.h>
37 #include <linux/syscalls.h>
38 #include <linux/signal.h>
39 #include <linux/posix-timers.h>
40 #include <linux/cn_proc.h>
41 #include <linux/mutex.h>
42 #include <linux/futex.h>
43 #include <linux/pipe_fs_i.h>
44 #include <linux/audit.h> /* for audit_free() */
45 #include <linux/resource.h>
46 #include <linux/blkdev.h>
47 #include <linux/task_io_accounting_ops.h>
48 #include <linux/tracehook.h>
49 #include <linux/init_task.h>
50 #include <trace/sched.h>
51
52 #include <asm/uaccess.h>
53 #include <asm/unistd.h>
54 #include <asm/pgtable.h>
55 #include <asm/mmu_context.h>
56 #include "cred-internals.h"
57
58 DEFINE_TRACE(sched_process_free);
59 DEFINE_TRACE(sched_process_exit);
60 DEFINE_TRACE(sched_process_wait);
61
62 static void exit_mm(struct task_struct * tsk);
63
64 static inline int task_detached(struct task_struct *p)
65 {
66         return p->exit_signal == -1;
67 }
68
69 static void __unhash_process(struct task_struct *p)
70 {
71         nr_threads--;
72         detach_pid(p, PIDTYPE_PID);
73         if (thread_group_leader(p)) {
74                 detach_pid(p, PIDTYPE_PGID);
75                 detach_pid(p, PIDTYPE_SID);
76
77                 list_del_rcu(&p->tasks);
78                 __get_cpu_var(process_counts)--;
79         }
80         list_del_rcu(&p->thread_group);
81         list_del_init(&p->sibling);
82 }
83
84 /*
85  * This function expects the tasklist_lock write-locked.
86  */
87 static void __exit_signal(struct task_struct *tsk)
88 {
89         struct signal_struct *sig = tsk->signal;
90         struct sighand_struct *sighand;
91
92         BUG_ON(!sig);
93         BUG_ON(!atomic_read(&sig->count));
94
95         sighand = rcu_dereference(tsk->sighand);
96         spin_lock(&sighand->siglock);
97
98         posix_cpu_timers_exit(tsk);
99         if (atomic_dec_and_test(&sig->count))
100                 posix_cpu_timers_exit_group(tsk);
101         else {
102                 /*
103                  * If there is any task waiting for the group exit
104                  * then notify it:
105                  */
106                 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count)
107                         wake_up_process(sig->group_exit_task);
108
109                 if (tsk == sig->curr_target)
110                         sig->curr_target = next_thread(tsk);
111                 /*
112                  * Accumulate here the counters for all threads but the
113                  * group leader as they die, so they can be added into
114                  * the process-wide totals when those are taken.
115                  * The group leader stays around as a zombie as long
116                  * as there are other threads.  When it gets reaped,
117                  * the exit.c code will add its counts into these totals.
118                  * We won't ever get here for the group leader, since it
119                  * will have been the last reference on the signal_struct.
120                  */
121                 sig->gtime = cputime_add(sig->gtime, task_gtime(tsk));
122                 sig->min_flt += tsk->min_flt;
123                 sig->maj_flt += tsk->maj_flt;
124                 sig->nvcsw += tsk->nvcsw;
125                 sig->nivcsw += tsk->nivcsw;
126                 sig->inblock += task_io_get_inblock(tsk);
127                 sig->oublock += task_io_get_oublock(tsk);
128                 task_io_accounting_add(&sig->ioac, &tsk->ioac);
129                 sig = NULL; /* Marker for below. */
130         }
131
132         __unhash_process(tsk);
133
134         /*
135          * Do this under ->siglock, we can race with another thread
136          * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
137          */
138         flush_sigqueue(&tsk->pending);
139
140         tsk->signal = NULL;
141         tsk->sighand = NULL;
142         spin_unlock(&sighand->siglock);
143
144         __cleanup_sighand(sighand);
145         clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
146         if (sig) {
147                 flush_sigqueue(&sig->shared_pending);
148                 taskstats_tgid_free(sig);
149                 /*
150                  * Make sure ->signal can't go away under rq->lock,
151                  * see account_group_exec_runtime().
152                  */
153                 task_rq_unlock_wait(tsk);
154                 __cleanup_signal(sig);
155         }
156 }
157
158 static void delayed_put_task_struct(struct rcu_head *rhp)
159 {
160         struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
161
162         trace_sched_process_free(tsk);
163         put_task_struct(tsk);
164 }
165
166
167 void release_task(struct task_struct * p)
168 {
169         struct task_struct *leader;
170         int zap_leader;
171 repeat:
172         tracehook_prepare_release_task(p);
173         /* don't need to get the RCU readlock here - the process is dead and
174          * can't be modifying its own credentials */
175         atomic_dec(&__task_cred(p)->user->processes);
176
177         proc_flush_task(p);
178         write_lock_irq(&tasklist_lock);
179         tracehook_finish_release_task(p);
180         __exit_signal(p);
181
182         /*
183          * If we are the last non-leader member of the thread
184          * group, and the leader is zombie, then notify the
185          * group leader's parent process. (if it wants notification.)
186          */
187         zap_leader = 0;
188         leader = p->group_leader;
189         if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
190                 BUG_ON(task_detached(leader));
191                 do_notify_parent(leader, leader->exit_signal);
192                 /*
193                  * If we were the last child thread and the leader has
194                  * exited already, and the leader's parent ignores SIGCHLD,
195                  * then we are the one who should release the leader.
196                  *
197                  * do_notify_parent() will have marked it self-reaping in
198                  * that case.
199                  */
200                 zap_leader = task_detached(leader);
201
202                 /*
203                  * This maintains the invariant that release_task()
204                  * only runs on a task in EXIT_DEAD, just for sanity.
205                  */
206                 if (zap_leader)
207                         leader->exit_state = EXIT_DEAD;
208         }
209
210         write_unlock_irq(&tasklist_lock);
211         release_thread(p);
212         call_rcu(&p->rcu, delayed_put_task_struct);
213
214         p = leader;
215         if (unlikely(zap_leader))
216                 goto repeat;
217 }
218
219 /*
220  * This checks not only the pgrp, but falls back on the pid if no
221  * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
222  * without this...
223  *
224  * The caller must hold rcu lock or the tasklist lock.
225  */
226 struct pid *session_of_pgrp(struct pid *pgrp)
227 {
228         struct task_struct *p;
229         struct pid *sid = NULL;
230
231         p = pid_task(pgrp, PIDTYPE_PGID);
232         if (p == NULL)
233                 p = pid_task(pgrp, PIDTYPE_PID);
234         if (p != NULL)
235                 sid = task_session(p);
236
237         return sid;
238 }
239
240 /*
241  * Determine if a process group is "orphaned", according to the POSIX
242  * definition in 2.2.2.52.  Orphaned process groups are not to be affected
243  * by terminal-generated stop signals.  Newly orphaned process groups are
244  * to receive a SIGHUP and a SIGCONT.
245  *
246  * "I ask you, have you ever known what it is to be an orphan?"
247  */
248 static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
249 {
250         struct task_struct *p;
251
252         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
253                 if ((p == ignored_task) ||
254                     (p->exit_state && thread_group_empty(p)) ||
255                     is_global_init(p->real_parent))
256                         continue;
257
258                 if (task_pgrp(p->real_parent) != pgrp &&
259                     task_session(p->real_parent) == task_session(p))
260                         return 0;
261         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
262
263         return 1;
264 }
265
266 int is_current_pgrp_orphaned(void)
267 {
268         int retval;
269
270         read_lock(&tasklist_lock);
271         retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
272         read_unlock(&tasklist_lock);
273
274         return retval;
275 }
276
277 static int has_stopped_jobs(struct pid *pgrp)
278 {
279         int retval = 0;
280         struct task_struct *p;
281
282         do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
283                 if (!task_is_stopped(p))
284                         continue;
285                 retval = 1;
286                 break;
287         } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
288         return retval;
289 }
290
291 /*
292  * Check to see if any process groups have become orphaned as
293  * a result of our exiting, and if they have any stopped jobs,
294  * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
295  */
296 static void
297 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
298 {
299         struct pid *pgrp = task_pgrp(tsk);
300         struct task_struct *ignored_task = tsk;
301
302         if (!parent)
303                  /* exit: our father is in a different pgrp than
304                   * we are and we were the only connection outside.
305                   */
306                 parent = tsk->real_parent;
307         else
308                 /* reparent: our child is in a different pgrp than
309                  * we are, and it was the only connection outside.
310                  */
311                 ignored_task = NULL;
312
313         if (task_pgrp(parent) != pgrp &&
314             task_session(parent) == task_session(tsk) &&
315             will_become_orphaned_pgrp(pgrp, ignored_task) &&
316             has_stopped_jobs(pgrp)) {
317                 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
318                 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
319         }
320 }
321
322 /**
323  * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
324  *
325  * If a kernel thread is launched as a result of a system call, or if
326  * it ever exits, it should generally reparent itself to kthreadd so it
327  * isn't in the way of other processes and is correctly cleaned up on exit.
328  *
329  * The various task state such as scheduling policy and priority may have
330  * been inherited from a user process, so we reset them to sane values here.
331  *
332  * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
333  */
334 static void reparent_to_kthreadd(void)
335 {
336         write_lock_irq(&tasklist_lock);
337
338         ptrace_unlink(current);
339         /* Reparent to init */
340         current->real_parent = current->parent = kthreadd_task;
341         list_move_tail(&current->sibling, &current->real_parent->children);
342
343         /* Set the exit signal to SIGCHLD so we signal init on exit */
344         current->exit_signal = SIGCHLD;
345
346         if (task_nice(current) < 0)
347                 set_user_nice(current, 0);
348         /* cpus_allowed? */
349         /* rt_priority? */
350         /* signals? */
351         memcpy(current->signal->rlim, init_task.signal->rlim,
352                sizeof(current->signal->rlim));
353
354         atomic_inc(&init_cred.usage);
355         commit_creds(&init_cred);
356         write_unlock_irq(&tasklist_lock);
357 }
358
359 void __set_special_pids(struct pid *pid)
360 {
361         struct task_struct *curr = current->group_leader;
362         pid_t nr = pid_nr(pid);
363
364         if (task_session(curr) != pid) {
365                 change_pid(curr, PIDTYPE_SID, pid);
366                 set_task_session(curr, nr);
367         }
368         if (task_pgrp(curr) != pid) {
369                 change_pid(curr, PIDTYPE_PGID, pid);
370                 set_task_pgrp(curr, nr);
371         }
372 }
373
374 static void set_special_pids(struct pid *pid)
375 {
376         write_lock_irq(&tasklist_lock);
377         __set_special_pids(pid);
378         write_unlock_irq(&tasklist_lock);
379 }
380
381 /*
382  * Let kernel threads use this to say that they
383  * allow a certain signal (since daemonize() will
384  * have disabled all of them by default).
385  */
386 int allow_signal(int sig)
387 {
388         if (!valid_signal(sig) || sig < 1)
389                 return -EINVAL;
390
391         spin_lock_irq(&current->sighand->siglock);
392         sigdelset(&current->blocked, sig);
393         if (!current->mm) {
394                 /* Kernel threads handle their own signals.
395                    Let the signal code know it'll be handled, so
396                    that they don't get converted to SIGKILL or
397                    just silently dropped */
398                 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
399         }
400         recalc_sigpending();
401         spin_unlock_irq(&current->sighand->siglock);
402         return 0;
403 }
404
405 EXPORT_SYMBOL(allow_signal);
406
407 int disallow_signal(int sig)
408 {
409         if (!valid_signal(sig) || sig < 1)
410                 return -EINVAL;
411
412         spin_lock_irq(&current->sighand->siglock);
413         current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
414         recalc_sigpending();
415         spin_unlock_irq(&current->sighand->siglock);
416         return 0;
417 }
418
419 EXPORT_SYMBOL(disallow_signal);
420
421 /*
422  *      Put all the gunge required to become a kernel thread without
423  *      attached user resources in one place where it belongs.
424  */
425
426 void daemonize(const char *name, ...)
427 {
428         va_list args;
429         struct fs_struct *fs;
430         sigset_t blocked;
431
432         va_start(args, name);
433         vsnprintf(current->comm, sizeof(current->comm), name, args);
434         va_end(args);
435
436         /*
437          * If we were started as result of loading a module, close all of the
438          * user space pages.  We don't need them, and if we didn't close them
439          * they would be locked into memory.
440          */
441         exit_mm(current);
442         /*
443          * We don't want to have TIF_FREEZE set if the system-wide hibernation
444          * or suspend transition begins right now.
445          */
446         current->flags |= (PF_NOFREEZE | PF_KTHREAD);
447
448         if (current->nsproxy != &init_nsproxy) {
449                 get_nsproxy(&init_nsproxy);
450                 switch_task_namespaces(current, &init_nsproxy);
451         }
452         set_special_pids(&init_struct_pid);
453         proc_clear_tty(current);
454
455         /* Block and flush all signals */
456         sigfillset(&blocked);
457         sigprocmask(SIG_BLOCK, &blocked, NULL);
458         flush_signals(current);
459
460         /* Become as one with the init task */
461
462         exit_fs(current);       /* current->fs->count--; */
463         fs = init_task.fs;
464         current->fs = fs;
465         atomic_inc(&fs->count);
466
467         exit_files(current);
468         current->files = init_task.files;
469         atomic_inc(&current->files->count);
470
471         reparent_to_kthreadd();
472 }
473
474 EXPORT_SYMBOL(daemonize);
475
476 static void close_files(struct files_struct * files)
477 {
478         int i, j;
479         struct fdtable *fdt;
480
481         j = 0;
482
483         /*
484          * It is safe to dereference the fd table without RCU or
485          * ->file_lock because this is the last reference to the
486          * files structure.
487          */
488         fdt = files_fdtable(files);
489         for (;;) {
490                 unsigned long set;
491                 i = j * __NFDBITS;
492                 if (i >= fdt->max_fds)
493                         break;
494                 set = fdt->open_fds->fds_bits[j++];
495                 while (set) {
496                         if (set & 1) {
497                                 struct file * file = xchg(&fdt->fd[i], NULL);
498                                 if (file) {
499                                         filp_close(file, files);
500                                         cond_resched();
501                                 }
502                         }
503                         i++;
504                         set >>= 1;
505                 }
506         }
507 }
508
509 struct files_struct *get_files_struct(struct task_struct *task)
510 {
511         struct files_struct *files;
512
513         task_lock(task);
514         files = task->files;
515         if (files)
516                 atomic_inc(&files->count);
517         task_unlock(task);
518
519         return files;
520 }
521
522 void put_files_struct(struct files_struct *files)
523 {
524         struct fdtable *fdt;
525
526         if (atomic_dec_and_test(&files->count)) {
527                 close_files(files);
528                 /*
529                  * Free the fd and fdset arrays if we expanded them.
530                  * If the fdtable was embedded, pass files for freeing
531                  * at the end of the RCU grace period. Otherwise,
532                  * you can free files immediately.
533                  */
534                 fdt = files_fdtable(files);
535                 if (fdt != &files->fdtab)
536                         kmem_cache_free(files_cachep, files);
537                 free_fdtable(fdt);
538         }
539 }
540
541 void reset_files_struct(struct files_struct *files)
542 {
543         struct task_struct *tsk = current;
544         struct files_struct *old;
545
546         old = tsk->files;
547         task_lock(tsk);
548         tsk->files = files;
549         task_unlock(tsk);
550         put_files_struct(old);
551 }
552
553 void exit_files(struct task_struct *tsk)
554 {
555         struct files_struct * files = tsk->files;
556
557         if (files) {
558                 task_lock(tsk);
559                 tsk->files = NULL;
560                 task_unlock(tsk);
561                 put_files_struct(files);
562         }
563 }
564
565 void put_fs_struct(struct fs_struct *fs)
566 {
567         /* No need to hold fs->lock if we are killing it */
568         if (atomic_dec_and_test(&fs->count)) {
569                 path_put(&fs->root);
570                 path_put(&fs->pwd);
571                 kmem_cache_free(fs_cachep, fs);
572         }
573 }
574
575 void exit_fs(struct task_struct *tsk)
576 {
577         struct fs_struct * fs = tsk->fs;
578
579         if (fs) {
580                 task_lock(tsk);
581                 tsk->fs = NULL;
582                 task_unlock(tsk);
583                 put_fs_struct(fs);
584         }
585 }
586
587 EXPORT_SYMBOL_GPL(exit_fs);
588
589 #ifdef CONFIG_MM_OWNER
590 /*
591  * Task p is exiting and it owned mm, lets find a new owner for it
592  */
593 static inline int
594 mm_need_new_owner(struct mm_struct *mm, struct task_struct *p)
595 {
596         /*
597          * If there are other users of the mm and the owner (us) is exiting
598          * we need to find a new owner to take on the responsibility.
599          */
600         if (atomic_read(&mm->mm_users) <= 1)
601                 return 0;
602         if (mm->owner != p)
603                 return 0;
604         return 1;
605 }
606
607 void mm_update_next_owner(struct mm_struct *mm)
608 {
609         struct task_struct *c, *g, *p = current;
610
611 retry:
612         if (!mm_need_new_owner(mm, p))
613                 return;
614
615         read_lock(&tasklist_lock);
616         /*
617          * Search in the children
618          */
619         list_for_each_entry(c, &p->children, sibling) {
620                 if (c->mm == mm)
621                         goto assign_new_owner;
622         }
623
624         /*
625          * Search in the siblings
626          */
627         list_for_each_entry(c, &p->parent->children, sibling) {
628                 if (c->mm == mm)
629                         goto assign_new_owner;
630         }
631
632         /*
633          * Search through everything else. We should not get
634          * here often
635          */
636         do_each_thread(g, c) {
637                 if (c->mm == mm)
638                         goto assign_new_owner;
639         } while_each_thread(g, c);
640
641         read_unlock(&tasklist_lock);
642         /*
643          * We found no owner yet mm_users > 1: this implies that we are
644          * most likely racing with swapoff (try_to_unuse()) or /proc or
645          * ptrace or page migration (get_task_mm()).  Mark owner as NULL,
646          * so that subsystems can understand the callback and take action.
647          */
648         down_write(&mm->mmap_sem);
649         cgroup_mm_owner_callbacks(mm->owner, NULL);
650         mm->owner = NULL;
651         up_write(&mm->mmap_sem);
652         return;
653
654 assign_new_owner:
655         BUG_ON(c == p);
656         get_task_struct(c);
657         read_unlock(&tasklist_lock);
658         down_write(&mm->mmap_sem);
659         /*
660          * The task_lock protects c->mm from changing.
661          * We always want mm->owner->mm == mm
662          */
663         task_lock(c);
664         if (c->mm != mm) {
665                 task_unlock(c);
666                 up_write(&mm->mmap_sem);
667                 put_task_struct(c);
668                 goto retry;
669         }
670         cgroup_mm_owner_callbacks(mm->owner, c);
671         mm->owner = c;
672         task_unlock(c);
673         up_write(&mm->mmap_sem);
674         put_task_struct(c);
675 }
676 #endif /* CONFIG_MM_OWNER */
677
678 /*
679  * Turn us into a lazy TLB process if we
680  * aren't already..
681  */
682 static void exit_mm(struct task_struct * tsk)
683 {
684         struct mm_struct *mm = tsk->mm;
685         struct core_state *core_state;
686
687         mm_release(tsk, mm);
688         if (!mm)
689                 return;
690         /*
691          * Serialize with any possible pending coredump.
692          * We must hold mmap_sem around checking core_state
693          * and clearing tsk->mm.  The core-inducing thread
694          * will increment ->nr_threads for each thread in the
695          * group with ->mm != NULL.
696          */
697         down_read(&mm->mmap_sem);
698         core_state = mm->core_state;
699         if (core_state) {
700                 struct core_thread self;
701                 up_read(&mm->mmap_sem);
702
703                 self.task = tsk;
704                 self.next = xchg(&core_state->dumper.next, &self);
705                 /*
706                  * Implies mb(), the result of xchg() must be visible
707                  * to core_state->dumper.
708                  */
709                 if (atomic_dec_and_test(&core_state->nr_threads))
710                         complete(&core_state->startup);
711
712                 for (;;) {
713                         set_task_state(tsk, TASK_UNINTERRUPTIBLE);
714                         if (!self.task) /* see coredump_finish() */
715                                 break;
716                         schedule();
717                 }
718                 __set_task_state(tsk, TASK_RUNNING);
719                 down_read(&mm->mmap_sem);
720         }
721         atomic_inc(&mm->mm_count);
722         BUG_ON(mm != tsk->active_mm);
723         /* more a memory barrier than a real lock */
724         task_lock(tsk);
725         tsk->mm = NULL;
726         up_read(&mm->mmap_sem);
727         enter_lazy_tlb(mm, current);
728         /* We don't want this task to be frozen prematurely */
729         clear_freeze_flag(tsk);
730         task_unlock(tsk);
731         mm_update_next_owner(mm);
732         mmput(mm);
733 }
734
735 /*
736  * Return nonzero if @parent's children should reap themselves.
737  *
738  * Called with write_lock_irq(&tasklist_lock) held.
739  */
740 static int ignoring_children(struct task_struct *parent)
741 {
742         int ret;
743         struct sighand_struct *psig = parent->sighand;
744         unsigned long flags;
745         spin_lock_irqsave(&psig->siglock, flags);
746         ret = (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
747                (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT));
748         spin_unlock_irqrestore(&psig->siglock, flags);
749         return ret;
750 }
751
752 /*
753  * Detach all tasks we were using ptrace on.
754  * Any that need to be release_task'd are put on the @dead list.
755  *
756  * Called with write_lock(&tasklist_lock) held.
757  */
758 static void ptrace_exit(struct task_struct *parent, struct list_head *dead)
759 {
760         struct task_struct *p, *n;
761         int ign = -1;
762
763         list_for_each_entry_safe(p, n, &parent->ptraced, ptrace_entry) {
764                 __ptrace_unlink(p);
765
766                 if (p->exit_state != EXIT_ZOMBIE)
767                         continue;
768
769                 /*
770                  * If it's a zombie, our attachedness prevented normal
771                  * parent notification or self-reaping.  Do notification
772                  * now if it would have happened earlier.  If it should
773                  * reap itself, add it to the @dead list.  We can't call
774                  * release_task() here because we already hold tasklist_lock.
775                  *
776                  * If it's our own child, there is no notification to do.
777                  * But if our normal children self-reap, then this child
778                  * was prevented by ptrace and we must reap it now.
779                  */
780                 if (!task_detached(p) && thread_group_empty(p)) {
781                         if (!same_thread_group(p->real_parent, parent))
782                                 do_notify_parent(p, p->exit_signal);
783                         else {
784                                 if (ign < 0)
785                                         ign = ignoring_children(parent);
786                                 if (ign)
787                                         p->exit_signal = -1;
788                         }
789                 }
790
791                 if (task_detached(p)) {
792                         /*
793                          * Mark it as in the process of being reaped.
794                          */
795                         p->exit_state = EXIT_DEAD;
796                         list_add(&p->ptrace_entry, dead);
797                 }
798         }
799 }
800
801 /*
802  * Finish up exit-time ptrace cleanup.
803  *
804  * Called without locks.
805  */
806 static void ptrace_exit_finish(struct task_struct *parent,
807                                struct list_head *dead)
808 {
809         struct task_struct *p, *n;
810
811         BUG_ON(!list_empty(&parent->ptraced));
812
813         list_for_each_entry_safe(p, n, dead, ptrace_entry) {
814                 list_del_init(&p->ptrace_entry);
815                 release_task(p);
816         }
817 }
818
819 static void reparent_thread(struct task_struct *p, struct task_struct *father)
820 {
821         if (p->pdeath_signal)
822                 /* We already hold the tasklist_lock here.  */
823                 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
824
825         list_move_tail(&p->sibling, &p->real_parent->children);
826
827         /* If this is a threaded reparent there is no need to
828          * notify anyone anything has happened.
829          */
830         if (same_thread_group(p->real_parent, father))
831                 return;
832
833         /* We don't want people slaying init.  */
834         if (!task_detached(p))
835                 p->exit_signal = SIGCHLD;
836
837         /* If we'd notified the old parent about this child's death,
838          * also notify the new parent.
839          */
840         if (!ptrace_reparented(p) &&
841             p->exit_state == EXIT_ZOMBIE &&
842             !task_detached(p) && thread_group_empty(p))
843                 do_notify_parent(p, p->exit_signal);
844
845         kill_orphaned_pgrp(p, father);
846 }
847
848 /*
849  * When we die, we re-parent all our children.
850  * Try to give them to another thread in our thread
851  * group, and if no such member exists, give it to
852  * the child reaper process (ie "init") in our pid
853  * space.
854  */
855 static struct task_struct *find_new_reaper(struct task_struct *father)
856 {
857         struct pid_namespace *pid_ns = task_active_pid_ns(father);
858         struct task_struct *thread;
859
860         thread = father;
861         while_each_thread(father, thread) {
862                 if (thread->flags & PF_EXITING)
863                         continue;
864                 if (unlikely(pid_ns->child_reaper == father))
865                         pid_ns->child_reaper = thread;
866                 return thread;
867         }
868
869         if (unlikely(pid_ns->child_reaper == father)) {
870                 write_unlock_irq(&tasklist_lock);
871                 if (unlikely(pid_ns == &init_pid_ns))
872                         panic("Attempted to kill init!");
873
874                 zap_pid_ns_processes(pid_ns);
875                 write_lock_irq(&tasklist_lock);
876                 /*
877                  * We can not clear ->child_reaper or leave it alone.
878                  * There may by stealth EXIT_DEAD tasks on ->children,
879                  * forget_original_parent() must move them somewhere.
880                  */
881                 pid_ns->child_reaper = init_pid_ns.child_reaper;
882         }
883
884         return pid_ns->child_reaper;
885 }
886
887 static void forget_original_parent(struct task_struct *father)
888 {
889         struct task_struct *p, *n, *reaper;
890         LIST_HEAD(ptrace_dead);
891
892         write_lock_irq(&tasklist_lock);
893         reaper = find_new_reaper(father);
894         /*
895          * First clean up ptrace if we were using it.
896          */
897         ptrace_exit(father, &ptrace_dead);
898
899         list_for_each_entry_safe(p, n, &father->children, sibling) {
900                 p->real_parent = reaper;
901                 if (p->parent == father) {
902                         BUG_ON(p->ptrace);
903                         p->parent = p->real_parent;
904                 }
905                 reparent_thread(p, father);
906         }
907
908         write_unlock_irq(&tasklist_lock);
909         BUG_ON(!list_empty(&father->children));
910
911         ptrace_exit_finish(father, &ptrace_dead);
912 }
913
914 /*
915  * Send signals to all our closest relatives so that they know
916  * to properly mourn us..
917  */
918 static void exit_notify(struct task_struct *tsk, int group_dead)
919 {
920         int signal;
921         void *cookie;
922
923         /*
924          * This does two things:
925          *
926          * A.  Make init inherit all the child processes
927          * B.  Check to see if any process groups have become orphaned
928          *      as a result of our exiting, and if they have any stopped
929          *      jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
930          */
931         forget_original_parent(tsk);
932         exit_task_namespaces(tsk);
933
934         write_lock_irq(&tasklist_lock);
935         if (group_dead)
936                 kill_orphaned_pgrp(tsk->group_leader, NULL);
937
938         /* Let father know we died
939          *
940          * Thread signals are configurable, but you aren't going to use
941          * that to send signals to arbitary processes.
942          * That stops right now.
943          *
944          * If the parent exec id doesn't match the exec id we saved
945          * when we started then we know the parent has changed security
946          * domain.
947          *
948          * If our self_exec id doesn't match our parent_exec_id then
949          * we have changed execution domain as these two values started
950          * the same after a fork.
951          */
952         if (tsk->exit_signal != SIGCHLD && !task_detached(tsk) &&
953             (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
954              tsk->self_exec_id != tsk->parent_exec_id) &&
955             !capable(CAP_KILL))
956                 tsk->exit_signal = SIGCHLD;
957
958         signal = tracehook_notify_death(tsk, &cookie, group_dead);
959         if (signal >= 0)
960                 signal = do_notify_parent(tsk, signal);
961
962         tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE;
963
964         /* mt-exec, de_thread() is waiting for us */
965         if (thread_group_leader(tsk) &&
966             tsk->signal->group_exit_task &&
967             tsk->signal->notify_count < 0)
968                 wake_up_process(tsk->signal->group_exit_task);
969
970         write_unlock_irq(&tasklist_lock);
971
972         tracehook_report_death(tsk, signal, cookie, group_dead);
973
974         /* If the process is dead, release it - nobody will wait for it */
975         if (signal == DEATH_REAP)
976                 release_task(tsk);
977 }
978
979 #ifdef CONFIG_DEBUG_STACK_USAGE
980 static void check_stack_usage(void)
981 {
982         static DEFINE_SPINLOCK(low_water_lock);
983         static int lowest_to_date = THREAD_SIZE;
984         unsigned long free;
985
986         free = stack_not_used(current);
987
988         if (free >= lowest_to_date)
989                 return;
990
991         spin_lock(&low_water_lock);
992         if (free < lowest_to_date) {
993                 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
994                                 "left\n",
995                                 current->comm, free);
996                 lowest_to_date = free;
997         }
998         spin_unlock(&low_water_lock);
999 }
1000 #else
1001 static inline void check_stack_usage(void) {}
1002 #endif
1003
1004 NORET_TYPE void do_exit(long code)
1005 {
1006         struct task_struct *tsk = current;
1007         int group_dead;
1008
1009         profile_task_exit(tsk);
1010
1011         WARN_ON(atomic_read(&tsk->fs_excl));
1012
1013         if (unlikely(in_interrupt()))
1014                 panic("Aiee, killing interrupt handler!");
1015         if (unlikely(!tsk->pid))
1016                 panic("Attempted to kill the idle task!");
1017
1018         tracehook_report_exit(&code);
1019
1020         /*
1021          * We're taking recursive faults here in do_exit. Safest is to just
1022          * leave this task alone and wait for reboot.
1023          */
1024         if (unlikely(tsk->flags & PF_EXITING)) {
1025                 printk(KERN_ALERT
1026                         "Fixing recursive fault but reboot is needed!\n");
1027                 /*
1028                  * We can do this unlocked here. The futex code uses
1029                  * this flag just to verify whether the pi state
1030                  * cleanup has been done or not. In the worst case it
1031                  * loops once more. We pretend that the cleanup was
1032                  * done as there is no way to return. Either the
1033                  * OWNER_DIED bit is set by now or we push the blocked
1034                  * task into the wait for ever nirwana as well.
1035                  */
1036                 tsk->flags |= PF_EXITPIDONE;
1037                 set_current_state(TASK_UNINTERRUPTIBLE);
1038                 schedule();
1039         }
1040
1041         exit_signals(tsk);  /* sets PF_EXITING */
1042         /*
1043          * tsk->flags are checked in the futex code to protect against
1044          * an exiting task cleaning up the robust pi futexes.
1045          */
1046         smp_mb();
1047         spin_unlock_wait(&tsk->pi_lock);
1048
1049         if (unlikely(in_atomic()))
1050                 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
1051                                 current->comm, task_pid_nr(current),
1052                                 preempt_count());
1053
1054         acct_update_integrals(tsk);
1055         if (tsk->mm) {
1056                 update_hiwater_rss(tsk->mm);
1057                 update_hiwater_vm(tsk->mm);
1058         }
1059         group_dead = atomic_dec_and_test(&tsk->signal->live);
1060         if (group_dead) {
1061                 hrtimer_cancel(&tsk->signal->real_timer);
1062                 exit_itimers(tsk->signal);
1063         }
1064         acct_collect(code, group_dead);
1065         if (group_dead)
1066                 tty_audit_exit();
1067         if (unlikely(tsk->audit_context))
1068                 audit_free(tsk);
1069
1070         tsk->exit_code = code;
1071         taskstats_exit(tsk, group_dead);
1072
1073         exit_mm(tsk);
1074
1075         if (group_dead)
1076                 acct_process();
1077         trace_sched_process_exit(tsk);
1078
1079         exit_sem(tsk);
1080         exit_files(tsk);
1081         exit_fs(tsk);
1082         check_stack_usage();
1083         exit_thread();
1084         cgroup_exit(tsk, 1);
1085
1086         if (group_dead && tsk->signal->leader)
1087                 disassociate_ctty(1);
1088
1089         module_put(task_thread_info(tsk)->exec_domain->module);
1090         if (tsk->binfmt)
1091                 module_put(tsk->binfmt->module);
1092
1093         proc_exit_connector(tsk);
1094         exit_notify(tsk, group_dead);
1095 #ifdef CONFIG_NUMA
1096         mpol_put(tsk->mempolicy);
1097         tsk->mempolicy = NULL;
1098 #endif
1099 #ifdef CONFIG_FUTEX
1100         /*
1101          * This must happen late, after the PID is not
1102          * hashed anymore:
1103          */
1104         if (unlikely(!list_empty(&tsk->pi_state_list)))
1105                 exit_pi_state_list(tsk);
1106         if (unlikely(current->pi_state_cache))
1107                 kfree(current->pi_state_cache);
1108 #endif
1109         /*
1110          * Make sure we are holding no locks:
1111          */
1112         debug_check_no_locks_held(tsk);
1113         /*
1114          * We can do this unlocked here. The futex code uses this flag
1115          * just to verify whether the pi state cleanup has been done
1116          * or not. In the worst case it loops once more.
1117          */
1118         tsk->flags |= PF_EXITPIDONE;
1119
1120         if (tsk->io_context)
1121                 exit_io_context();
1122
1123         if (tsk->splice_pipe)
1124                 __free_pipe_info(tsk->splice_pipe);
1125
1126         preempt_disable();
1127         /* causes final put_task_struct in finish_task_switch(). */
1128         tsk->state = TASK_DEAD;
1129         schedule();
1130         BUG();
1131         /* Avoid "noreturn function does return".  */
1132         for (;;)
1133                 cpu_relax();    /* For when BUG is null */
1134 }
1135
1136 EXPORT_SYMBOL_GPL(do_exit);
1137
1138 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
1139 {
1140         if (comp)
1141                 complete(comp);
1142
1143         do_exit(code);
1144 }
1145
1146 EXPORT_SYMBOL(complete_and_exit);
1147
1148 asmlinkage long sys_exit(int error_code)
1149 {
1150         do_exit((error_code&0xff)<<8);
1151 }
1152
1153 /*
1154  * Take down every thread in the group.  This is called by fatal signals
1155  * as well as by sys_exit_group (below).
1156  */
1157 NORET_TYPE void
1158 do_group_exit(int exit_code)
1159 {
1160         struct signal_struct *sig = current->signal;
1161
1162         BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1163
1164         if (signal_group_exit(sig))
1165                 exit_code = sig->group_exit_code;
1166         else if (!thread_group_empty(current)) {
1167                 struct sighand_struct *const sighand = current->sighand;
1168                 spin_lock_irq(&sighand->siglock);
1169                 if (signal_group_exit(sig))
1170                         /* Another thread got here before we took the lock.  */
1171                         exit_code = sig->group_exit_code;
1172                 else {
1173                         sig->group_exit_code = exit_code;
1174                         sig->flags = SIGNAL_GROUP_EXIT;
1175                         zap_other_threads(current);
1176                 }
1177                 spin_unlock_irq(&sighand->siglock);
1178         }
1179
1180         do_exit(exit_code);
1181         /* NOTREACHED */
1182 }
1183
1184 /*
1185  * this kills every thread in the thread group. Note that any externally
1186  * wait4()-ing process will get the correct exit code - even if this
1187  * thread is not the thread group leader.
1188  */
1189 asmlinkage void sys_exit_group(int error_code)
1190 {
1191         do_group_exit((error_code & 0xff) << 8);
1192 }
1193
1194 static struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
1195 {
1196         struct pid *pid = NULL;
1197         if (type == PIDTYPE_PID)
1198                 pid = task->pids[type].pid;
1199         else if (type < PIDTYPE_MAX)
1200                 pid = task->group_leader->pids[type].pid;
1201         return pid;
1202 }
1203
1204 static int eligible_child(enum pid_type type, struct pid *pid, int options,
1205                           struct task_struct *p)
1206 {
1207         int err;
1208
1209         if (type < PIDTYPE_MAX) {
1210                 if (task_pid_type(p, type) != pid)
1211                         return 0;
1212         }
1213
1214         /* Wait for all children (clone and not) if __WALL is set;
1215          * otherwise, wait for clone children *only* if __WCLONE is
1216          * set; otherwise, wait for non-clone children *only*.  (Note:
1217          * A "clone" child here is one that reports to its parent
1218          * using a signal other than SIGCHLD.) */
1219         if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1220             && !(options & __WALL))
1221                 return 0;
1222
1223         err = security_task_wait(p);
1224         if (err)
1225                 return err;
1226
1227         return 1;
1228 }
1229
1230 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1231                                int why, int status,
1232                                struct siginfo __user *infop,
1233                                struct rusage __user *rusagep)
1234 {
1235         int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1236
1237         put_task_struct(p);
1238         if (!retval)
1239                 retval = put_user(SIGCHLD, &infop->si_signo);
1240         if (!retval)
1241                 retval = put_user(0, &infop->si_errno);
1242         if (!retval)
1243                 retval = put_user((short)why, &infop->si_code);
1244         if (!retval)
1245                 retval = put_user(pid, &infop->si_pid);
1246         if (!retval)
1247                 retval = put_user(uid, &infop->si_uid);
1248         if (!retval)
1249                 retval = put_user(status, &infop->si_status);
1250         if (!retval)
1251                 retval = pid;
1252         return retval;
1253 }
1254
1255 /*
1256  * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
1257  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1258  * the lock and this task is uninteresting.  If we return nonzero, we have
1259  * released the lock and the system call should return.
1260  */
1261 static int wait_task_zombie(struct task_struct *p, int options,
1262                             struct siginfo __user *infop,
1263                             int __user *stat_addr, struct rusage __user *ru)
1264 {
1265         unsigned long state;
1266         int retval, status, traced;
1267         pid_t pid = task_pid_vnr(p);
1268         uid_t uid = __task_cred(p)->uid;
1269
1270         if (!likely(options & WEXITED))
1271                 return 0;
1272
1273         if (unlikely(options & WNOWAIT)) {
1274                 int exit_code = p->exit_code;
1275                 int why, status;
1276
1277                 get_task_struct(p);
1278                 read_unlock(&tasklist_lock);
1279                 if ((exit_code & 0x7f) == 0) {
1280                         why = CLD_EXITED;
1281                         status = exit_code >> 8;
1282                 } else {
1283                         why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1284                         status = exit_code & 0x7f;
1285                 }
1286                 return wait_noreap_copyout(p, pid, uid, why,
1287                                            status, infop, ru);
1288         }
1289
1290         /*
1291          * Try to move the task's state to DEAD
1292          * only one thread is allowed to do this:
1293          */
1294         state = xchg(&p->exit_state, EXIT_DEAD);
1295         if (state != EXIT_ZOMBIE) {
1296                 BUG_ON(state != EXIT_DEAD);
1297                 return 0;
1298         }
1299
1300         traced = ptrace_reparented(p);
1301
1302         if (likely(!traced)) {
1303                 struct signal_struct *psig;
1304                 struct signal_struct *sig;
1305                 struct task_cputime cputime;
1306
1307                 /*
1308                  * The resource counters for the group leader are in its
1309                  * own task_struct.  Those for dead threads in the group
1310                  * are in its signal_struct, as are those for the child
1311                  * processes it has previously reaped.  All these
1312                  * accumulate in the parent's signal_struct c* fields.
1313                  *
1314                  * We don't bother to take a lock here to protect these
1315                  * p->signal fields, because they are only touched by
1316                  * __exit_signal, which runs with tasklist_lock
1317                  * write-locked anyway, and so is excluded here.  We do
1318                  * need to protect the access to p->parent->signal fields,
1319                  * as other threads in the parent group can be right
1320                  * here reaping other children at the same time.
1321                  *
1322                  * We use thread_group_cputime() to get times for the thread
1323                  * group, which consolidates times for all threads in the
1324                  * group including the group leader.
1325                  */
1326                 thread_group_cputime(p, &cputime);
1327                 spin_lock_irq(&p->parent->sighand->siglock);
1328                 psig = p->parent->signal;
1329                 sig = p->signal;
1330                 psig->cutime =
1331                         cputime_add(psig->cutime,
1332                         cputime_add(cputime.utime,
1333                                     sig->cutime));
1334                 psig->cstime =
1335                         cputime_add(psig->cstime,
1336                         cputime_add(cputime.stime,
1337                                     sig->cstime));
1338                 psig->cgtime =
1339                         cputime_add(psig->cgtime,
1340                         cputime_add(p->gtime,
1341                         cputime_add(sig->gtime,
1342                                     sig->cgtime)));
1343                 psig->cmin_flt +=
1344                         p->min_flt + sig->min_flt + sig->cmin_flt;
1345                 psig->cmaj_flt +=
1346                         p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1347                 psig->cnvcsw +=
1348                         p->nvcsw + sig->nvcsw + sig->cnvcsw;
1349                 psig->cnivcsw +=
1350                         p->nivcsw + sig->nivcsw + sig->cnivcsw;
1351                 psig->cinblock +=
1352                         task_io_get_inblock(p) +
1353                         sig->inblock + sig->cinblock;
1354                 psig->coublock +=
1355                         task_io_get_oublock(p) +
1356                         sig->oublock + sig->coublock;
1357                 task_io_accounting_add(&psig->ioac, &p->ioac);
1358                 task_io_accounting_add(&psig->ioac, &sig->ioac);
1359                 spin_unlock_irq(&p->parent->sighand->siglock);
1360         }
1361
1362         /*
1363          * Now we are sure this task is interesting, and no other
1364          * thread can reap it because we set its state to EXIT_DEAD.
1365          */
1366         read_unlock(&tasklist_lock);
1367
1368         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1369         status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1370                 ? p->signal->group_exit_code : p->exit_code;
1371         if (!retval && stat_addr)
1372                 retval = put_user(status, stat_addr);
1373         if (!retval && infop)
1374                 retval = put_user(SIGCHLD, &infop->si_signo);
1375         if (!retval && infop)
1376                 retval = put_user(0, &infop->si_errno);
1377         if (!retval && infop) {
1378                 int why;
1379
1380                 if ((status & 0x7f) == 0) {
1381                         why = CLD_EXITED;
1382                         status >>= 8;
1383                 } else {
1384                         why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1385                         status &= 0x7f;
1386                 }
1387                 retval = put_user((short)why, &infop->si_code);
1388                 if (!retval)
1389                         retval = put_user(status, &infop->si_status);
1390         }
1391         if (!retval && infop)
1392                 retval = put_user(pid, &infop->si_pid);
1393         if (!retval && infop)
1394                 retval = put_user(uid, &infop->si_uid);
1395         if (!retval)
1396                 retval = pid;
1397
1398         if (traced) {
1399                 write_lock_irq(&tasklist_lock);
1400                 /* We dropped tasklist, ptracer could die and untrace */
1401                 ptrace_unlink(p);
1402                 /*
1403                  * If this is not a detached task, notify the parent.
1404                  * If it's still not detached after that, don't release
1405                  * it now.
1406                  */
1407                 if (!task_detached(p)) {
1408                         do_notify_parent(p, p->exit_signal);
1409                         if (!task_detached(p)) {
1410                                 p->exit_state = EXIT_ZOMBIE;
1411                                 p = NULL;
1412                         }
1413                 }
1414                 write_unlock_irq(&tasklist_lock);
1415         }
1416         if (p != NULL)
1417                 release_task(p);
1418
1419         return retval;
1420 }
1421
1422 /*
1423  * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
1424  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1425  * the lock and this task is uninteresting.  If we return nonzero, we have
1426  * released the lock and the system call should return.
1427  */
1428 static int wait_task_stopped(int ptrace, struct task_struct *p,
1429                              int options, struct siginfo __user *infop,
1430                              int __user *stat_addr, struct rusage __user *ru)
1431 {
1432         int retval, exit_code, why;
1433         uid_t uid = 0; /* unneeded, required by compiler */
1434         pid_t pid;
1435
1436         if (!(options & WUNTRACED))
1437                 return 0;
1438
1439         exit_code = 0;
1440         spin_lock_irq(&p->sighand->siglock);
1441
1442         if (unlikely(!task_is_stopped_or_traced(p)))
1443                 goto unlock_sig;
1444
1445         if (!ptrace && p->signal->group_stop_count > 0)
1446                 /*
1447                  * A group stop is in progress and this is the group leader.
1448                  * We won't report until all threads have stopped.
1449                  */
1450                 goto unlock_sig;
1451
1452         exit_code = p->exit_code;
1453         if (!exit_code)
1454                 goto unlock_sig;
1455
1456         if (!unlikely(options & WNOWAIT))
1457                 p->exit_code = 0;
1458
1459         /* don't need the RCU readlock here as we're holding a spinlock */
1460         uid = __task_cred(p)->uid;
1461 unlock_sig:
1462         spin_unlock_irq(&p->sighand->siglock);
1463         if (!exit_code)
1464                 return 0;
1465
1466         /*
1467          * Now we are pretty sure this task is interesting.
1468          * Make sure it doesn't get reaped out from under us while we
1469          * give up the lock and then examine it below.  We don't want to
1470          * keep holding onto the tasklist_lock while we call getrusage and
1471          * possibly take page faults for user memory.
1472          */
1473         get_task_struct(p);
1474         pid = task_pid_vnr(p);
1475         why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1476         read_unlock(&tasklist_lock);
1477
1478         if (unlikely(options & WNOWAIT))
1479                 return wait_noreap_copyout(p, pid, uid,
1480                                            why, exit_code,
1481                                            infop, ru);
1482
1483         retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1484         if (!retval && stat_addr)
1485                 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1486         if (!retval && infop)
1487                 retval = put_user(SIGCHLD, &infop->si_signo);
1488         if (!retval && infop)
1489                 retval = put_user(0, &infop->si_errno);
1490         if (!retval && infop)
1491                 retval = put_user((short)why, &infop->si_code);
1492         if (!retval && infop)
1493                 retval = put_user(exit_code, &infop->si_status);
1494         if (!retval && infop)
1495                 retval = put_user(pid, &infop->si_pid);
1496         if (!retval && infop)
1497                 retval = put_user(uid, &infop->si_uid);
1498         if (!retval)
1499                 retval = pid;
1500         put_task_struct(p);
1501
1502         BUG_ON(!retval);
1503         return retval;
1504 }
1505
1506 /*
1507  * Handle do_wait work for one task in a live, non-stopped state.
1508  * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
1509  * the lock and this task is uninteresting.  If we return nonzero, we have
1510  * released the lock and the system call should return.
1511  */
1512 static int wait_task_continued(struct task_struct *p, int options,
1513                                struct siginfo __user *infop,
1514                                int __user *stat_addr, struct rusage __user *ru)
1515 {
1516         int retval;
1517         pid_t pid;
1518         uid_t uid;
1519
1520         if (!unlikely(options & WCONTINUED))
1521                 return 0;
1522
1523         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1524                 return 0;
1525
1526         spin_lock_irq(&p->sighand->siglock);
1527         /* Re-check with the lock held.  */
1528         if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1529                 spin_unlock_irq(&p->sighand->siglock);
1530                 return 0;
1531         }
1532         if (!unlikely(options & WNOWAIT))
1533                 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1534         uid = __task_cred(p)->uid;
1535         spin_unlock_irq(&p->sighand->siglock);
1536
1537         pid = task_pid_vnr(p);
1538         get_task_struct(p);
1539         read_unlock(&tasklist_lock);
1540
1541         if (!infop) {
1542                 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1543                 put_task_struct(p);
1544                 if (!retval && stat_addr)
1545                         retval = put_user(0xffff, stat_addr);
1546                 if (!retval)
1547                         retval = pid;
1548         } else {
1549                 retval = wait_noreap_copyout(p, pid, uid,
1550                                              CLD_CONTINUED, SIGCONT,
1551                                              infop, ru);
1552                 BUG_ON(retval == 0);
1553         }
1554
1555         return retval;
1556 }
1557
1558 /*
1559  * Consider @p for a wait by @parent.
1560  *
1561  * -ECHILD should be in *@notask_error before the first call.
1562  * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1563  * Returns zero if the search for a child should continue;
1564  * then *@notask_error is 0 if @p is an eligible child,
1565  * or another error from security_task_wait(), or still -ECHILD.
1566  */
1567 static int wait_consider_task(struct task_struct *parent, int ptrace,
1568                               struct task_struct *p, int *notask_error,
1569                               enum pid_type type, struct pid *pid, int options,
1570                               struct siginfo __user *infop,
1571                               int __user *stat_addr, struct rusage __user *ru)
1572 {
1573         int ret = eligible_child(type, pid, options, p);
1574         if (!ret)
1575                 return ret;
1576
1577         if (unlikely(ret < 0)) {
1578                 /*
1579                  * If we have not yet seen any eligible child,
1580                  * then let this error code replace -ECHILD.
1581                  * A permission error will give the user a clue
1582                  * to look for security policy problems, rather
1583                  * than for mysterious wait bugs.
1584                  */
1585                 if (*notask_error)
1586                         *notask_error = ret;
1587         }
1588
1589         if (likely(!ptrace) && unlikely(p->ptrace)) {
1590                 /*
1591                  * This child is hidden by ptrace.
1592                  * We aren't allowed to see it now, but eventually we will.
1593                  */
1594                 *notask_error = 0;
1595                 return 0;
1596         }
1597
1598         if (p->exit_state == EXIT_DEAD)
1599                 return 0;
1600
1601         /*
1602          * We don't reap group leaders with subthreads.
1603          */
1604         if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p))
1605                 return wait_task_zombie(p, options, infop, stat_addr, ru);
1606
1607         /*
1608          * It's stopped or running now, so it might
1609          * later continue, exit, or stop again.
1610          */
1611         *notask_error = 0;
1612
1613         if (task_is_stopped_or_traced(p))
1614                 return wait_task_stopped(ptrace, p, options,
1615                                          infop, stat_addr, ru);
1616
1617         return wait_task_continued(p, options, infop, stat_addr, ru);
1618 }
1619
1620 /*
1621  * Do the work of do_wait() for one thread in the group, @tsk.
1622  *
1623  * -ECHILD should be in *@notask_error before the first call.
1624  * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1625  * Returns zero if the search for a child should continue; then
1626  * *@notask_error is 0 if there were any eligible children,
1627  * or another error from security_task_wait(), or still -ECHILD.
1628  */
1629 static int do_wait_thread(struct task_struct *tsk, int *notask_error,
1630                           enum pid_type type, struct pid *pid, int options,
1631                           struct siginfo __user *infop, int __user *stat_addr,
1632                           struct rusage __user *ru)
1633 {
1634         struct task_struct *p;
1635
1636         list_for_each_entry(p, &tsk->children, sibling) {
1637                 /*
1638                  * Do not consider detached threads.
1639                  */
1640                 if (!task_detached(p)) {
1641                         int ret = wait_consider_task(tsk, 0, p, notask_error,
1642                                                      type, pid, options,
1643                                                      infop, stat_addr, ru);
1644                         if (ret)
1645                                 return ret;
1646                 }
1647         }
1648
1649         return 0;
1650 }
1651
1652 static int ptrace_do_wait(struct task_struct *tsk, int *notask_error,
1653                           enum pid_type type, struct pid *pid, int options,
1654                           struct siginfo __user *infop, int __user *stat_addr,
1655                           struct rusage __user *ru)
1656 {
1657         struct task_struct *p;
1658
1659         /*
1660          * Traditionally we see ptrace'd stopped tasks regardless of options.
1661          */
1662         options |= WUNTRACED;
1663
1664         list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1665                 int ret = wait_consider_task(tsk, 1, p, notask_error,
1666                                              type, pid, options,
1667                                              infop, stat_addr, ru);
1668                 if (ret)
1669                         return ret;
1670         }
1671
1672         return 0;
1673 }
1674
1675 static long do_wait(enum pid_type type, struct pid *pid, int options,
1676                     struct siginfo __user *infop, int __user *stat_addr,
1677                     struct rusage __user *ru)
1678 {
1679         DECLARE_WAITQUEUE(wait, current);
1680         struct task_struct *tsk;
1681         int retval;
1682
1683         trace_sched_process_wait(pid);
1684
1685         add_wait_queue(&current->signal->wait_chldexit,&wait);
1686 repeat:
1687         /*
1688          * If there is nothing that can match our critiera just get out.
1689          * We will clear @retval to zero if we see any child that might later
1690          * match our criteria, even if we are not able to reap it yet.
1691          */
1692         retval = -ECHILD;
1693         if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type])))
1694                 goto end;
1695
1696         current->state = TASK_INTERRUPTIBLE;
1697         read_lock(&tasklist_lock);
1698         tsk = current;
1699         do {
1700                 int tsk_result = do_wait_thread(tsk, &retval,
1701                                                 type, pid, options,
1702                                                 infop, stat_addr, ru);
1703                 if (!tsk_result)
1704                         tsk_result = ptrace_do_wait(tsk, &retval,
1705                                                     type, pid, options,
1706                                                     infop, stat_addr, ru);
1707                 if (tsk_result) {
1708                         /*
1709                          * tasklist_lock is unlocked and we have a final result.
1710                          */
1711                         retval = tsk_result;
1712                         goto end;
1713                 }
1714
1715                 if (options & __WNOTHREAD)
1716                         break;
1717                 tsk = next_thread(tsk);
1718                 BUG_ON(tsk->signal != current->signal);
1719         } while (tsk != current);
1720         read_unlock(&tasklist_lock);
1721
1722         if (!retval && !(options & WNOHANG)) {
1723                 retval = -ERESTARTSYS;
1724                 if (!signal_pending(current)) {
1725                         schedule();
1726                         goto repeat;
1727                 }
1728         }
1729
1730 end:
1731         current->state = TASK_RUNNING;
1732         remove_wait_queue(&current->signal->wait_chldexit,&wait);
1733         if (infop) {
1734                 if (retval > 0)
1735                         retval = 0;
1736                 else {
1737                         /*
1738                          * For a WNOHANG return, clear out all the fields
1739                          * we would set so the user can easily tell the
1740                          * difference.
1741                          */
1742                         if (!retval)
1743                                 retval = put_user(0, &infop->si_signo);
1744                         if (!retval)
1745                                 retval = put_user(0, &infop->si_errno);
1746                         if (!retval)
1747                                 retval = put_user(0, &infop->si_code);
1748                         if (!retval)
1749                                 retval = put_user(0, &infop->si_pid);
1750                         if (!retval)
1751                                 retval = put_user(0, &infop->si_uid);
1752                         if (!retval)
1753                                 retval = put_user(0, &infop->si_status);
1754                 }
1755         }
1756         return retval;
1757 }
1758
1759 asmlinkage long sys_waitid(int which, pid_t upid,
1760                            struct siginfo __user *infop, int options,
1761                            struct rusage __user *ru)
1762 {
1763         struct pid *pid = NULL;
1764         enum pid_type type;
1765         long ret;
1766
1767         if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1768                 return -EINVAL;
1769         if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1770                 return -EINVAL;
1771
1772         switch (which) {
1773         case P_ALL:
1774                 type = PIDTYPE_MAX;
1775                 break;
1776         case P_PID:
1777                 type = PIDTYPE_PID;
1778                 if (upid <= 0)
1779                         return -EINVAL;
1780                 break;
1781         case P_PGID:
1782                 type = PIDTYPE_PGID;
1783                 if (upid <= 0)
1784                         return -EINVAL;
1785                 break;
1786         default:
1787                 return -EINVAL;
1788         }
1789
1790         if (type < PIDTYPE_MAX)
1791                 pid = find_get_pid(upid);
1792         ret = do_wait(type, pid, options, infop, NULL, ru);
1793         put_pid(pid);
1794
1795         /* avoid REGPARM breakage on x86: */
1796         asmlinkage_protect(5, ret, which, upid, infop, options, ru);
1797         return ret;
1798 }
1799
1800 asmlinkage long sys_wait4(pid_t upid, int __user *stat_addr,
1801                           int options, struct rusage __user *ru)
1802 {
1803         struct pid *pid = NULL;
1804         enum pid_type type;
1805         long ret;
1806
1807         if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1808                         __WNOTHREAD|__WCLONE|__WALL))
1809                 return -EINVAL;
1810
1811         if (upid == -1)
1812                 type = PIDTYPE_MAX;
1813         else if (upid < 0) {
1814                 type = PIDTYPE_PGID;
1815                 pid = find_get_pid(-upid);
1816         } else if (upid == 0) {
1817                 type = PIDTYPE_PGID;
1818                 pid = get_pid(task_pgrp(current));
1819         } else /* upid > 0 */ {
1820                 type = PIDTYPE_PID;
1821                 pid = find_get_pid(upid);
1822         }
1823
1824         ret = do_wait(type, pid, options | WEXITED, NULL, stat_addr, ru);
1825         put_pid(pid);
1826
1827         /* avoid REGPARM breakage on x86: */
1828         asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
1829         return ret;
1830 }
1831
1832 #ifdef __ARCH_WANT_SYS_WAITPID
1833
1834 /*
1835  * sys_waitpid() remains for compatibility. waitpid() should be
1836  * implemented by calling sys_wait4() from libc.a.
1837  */
1838 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1839 {
1840         return sys_wait4(pid, stat_addr, options, NULL);
1841 }
1842
1843 #endif