projects/linux·blob v2.6.21 · refs

1663 lines · 41.7 KiB

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