projects/linux·blob v2.6.22 · refs

1712 lines · 43.2 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/module.h>
11#include <linux/capability.h>
12#include <linux/completion.h>
13#include <linux/personality.h>
14#include <linux/tty.h>
15#include <linux/mnt_namespace.h>
16#include <linux/key.h>
17#include <linux/security.h>
18#include <linux/cpu.h>
19#include <linux/acct.h>
20#include <linux/tsacct_kern.h>
21#include <linux/file.h>
22#include <linux/binfmts.h>
23#include <linux/nsproxy.h>
24#include <linux/pid_namespace.h>
25#include <linux/ptrace.h>
26#include <linux/profile.h>
27#include <linux/signalfd.h>
28#include <linux/mount.h>
29#include <linux/proc_fs.h>
30#include <linux/kthread.h>
31#include <linux/mempolicy.h>
32#include <linux/taskstats_kern.h>
33#include <linux/delayacct.h>
34#include <linux/cpuset.h>
35#include <linux/syscalls.h>
36#include <linux/signal.h>
37#include <linux/posix-timers.h>
38#include <linux/cn_proc.h>
39#include <linux/mutex.h>
40#include <linux/futex.h>
41#include <linux/compat.h>
42#include <linux/pipe_fs_i.h>
43#include <linux/audit.h> /* for audit_free() */
44#include <linux/resource.h>
45#include <linux/blkdev.h>
46#include <linux/task_io_accounting_ops.h>
47
48#include <asm/uaccess.h>
49#include <asm/unistd.h>
50#include <asm/pgtable.h>
51#include <asm/mmu_context.h>
52
53extern void sem_exit (void);
54
55static void exit_mm(struct task_struct * tsk);
56
57static void __unhash_process(struct task_struct *p)
58{
59 nr_threads--;
60 detach_pid(p, PIDTYPE_PID);
61 if (thread_group_leader(p)) {
62 detach_pid(p, PIDTYPE_PGID);
63 detach_pid(p, PIDTYPE_SID);
64
65 list_del_rcu(&p->tasks);
66 __get_cpu_var(process_counts)--;
67 }
68 list_del_rcu(&p->thread_group);
69 remove_parent(p);
70}
71
72/*
73 * This function expects the tasklist_lock write-locked.
74 */
75static void __exit_signal(struct task_struct *tsk)
76{
77 struct signal_struct *sig = tsk->signal;
78 struct sighand_struct *sighand;
79
80 BUG_ON(!sig);
81 BUG_ON(!atomic_read(&sig->count));
82
83 rcu_read_lock();
84 sighand = rcu_dereference(tsk->sighand);
85 spin_lock(&sighand->siglock);
86
87 /*
88 * Notify that this sighand has been detached. This must
89 * be called with the tsk->sighand lock held. Also, this
90 * access tsk->sighand internally, so it must be called
91 * before tsk->sighand is reset.
92 */
93 signalfd_detach_locked(tsk);
94
95 posix_cpu_timers_exit(tsk);
96 if (atomic_dec_and_test(&sig->count))
97 posix_cpu_timers_exit_group(tsk);
98 else {
99 /*
100 * If there is any task waiting for the group exit
101 * then notify it:
102 */
103 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
104 wake_up_process(sig->group_exit_task);
105 sig->group_exit_task = NULL;
106 }
107 if (tsk == sig->curr_target)
108 sig->curr_target = next_thread(tsk);
109 /*
110 * Accumulate here the counters for all threads but the
111 * group leader as they die, so they can be added into
112 * the process-wide totals when those are taken.
113 * The group leader stays around as a zombie as long
114 * as there are other threads. When it gets reaped,
115 * the exit.c code will add its counts into these totals.
116 * We won't ever get here for the group leader, since it
117 * will have been the last reference on the signal_struct.
118 */
119 sig->utime = cputime_add(sig->utime, tsk->utime);
120 sig->stime = cputime_add(sig->stime, tsk->stime);
121 sig->min_flt += tsk->min_flt;
122 sig->maj_flt += tsk->maj_flt;
123 sig->nvcsw += tsk->nvcsw;
124 sig->nivcsw += tsk->nivcsw;
125 sig->sched_time += tsk->sched_time;
126 sig->inblock += task_io_get_inblock(tsk);
127 sig->oublock += task_io_get_oublock(tsk);
128 sig = NULL; /* Marker for below. */
129 }
130
131 __unhash_process(tsk);
132
133 tsk->signal = NULL;
134 tsk->sighand = NULL;
135 spin_unlock(&sighand->siglock);
136 rcu_read_unlock();
137
138 __cleanup_sighand(sighand);
139 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
140 flush_sigqueue(&tsk->pending);
141 if (sig) {
142 flush_sigqueue(&sig->shared_pending);
143 taskstats_tgid_free(sig);
144 __cleanup_signal(sig);
145 }
146}
147
148static void delayed_put_task_struct(struct rcu_head *rhp)
149{
150 put_task_struct(container_of(rhp, struct task_struct, rcu));
151}
152
153void release_task(struct task_struct * p)
154{
155 struct task_struct *leader;
156 int zap_leader;
157repeat:
158 atomic_dec(&p->user->processes);
159 write_lock_irq(&tasklist_lock);
160 ptrace_unlink(p);
161 BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
162 __exit_signal(p);
163
164 /*
165 * If we are the last non-leader member of the thread
166 * group, and the leader is zombie, then notify the
167 * group leader's parent process. (if it wants notification.)
168 */
169 zap_leader = 0;
170 leader = p->group_leader;
171 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
172 BUG_ON(leader->exit_signal == -1);
173 do_notify_parent(leader, leader->exit_signal);
174 /*
175 * If we were the last child thread and the leader has
176 * exited already, and the leader's parent ignores SIGCHLD,
177 * then we are the one who should release the leader.
178 *
179 * do_notify_parent() will have marked it self-reaping in
180 * that case.
181 */
182 zap_leader = (leader->exit_signal == -1);
183 }
184
185 sched_exit(p);
186 write_unlock_irq(&tasklist_lock);
187 proc_flush_task(p);
188 release_thread(p);
189 call_rcu(&p->rcu, delayed_put_task_struct);
190
191 p = leader;
192 if (unlikely(zap_leader))
193 goto repeat;
194}
195
196/*
197 * This checks not only the pgrp, but falls back on the pid if no
198 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
199 * without this...
200 *
201 * The caller must hold rcu lock or the tasklist lock.
202 */
203struct pid *session_of_pgrp(struct pid *pgrp)
204{
205 struct task_struct *p;
206 struct pid *sid = NULL;
207
208 p = pid_task(pgrp, PIDTYPE_PGID);
209 if (p == NULL)
210 p = pid_task(pgrp, PIDTYPE_PID);
211 if (p != NULL)
212 sid = task_session(p);
213
214 return sid;
215}
216
217/*
218 * Determine if a process group is "orphaned", according to the POSIX
219 * definition in 2.2.2.52. Orphaned process groups are not to be affected
220 * by terminal-generated stop signals. Newly orphaned process groups are
221 * to receive a SIGHUP and a SIGCONT.
222 *
223 * "I ask you, have you ever known what it is to be an orphan?"
224 */
225static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
226{
227 struct task_struct *p;
228 int ret = 1;
229
230 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
231 if (p == ignored_task
232 || p->exit_state
233 || is_init(p->real_parent))
234 continue;
235 if (task_pgrp(p->real_parent) != pgrp &&
236 task_session(p->real_parent) == task_session(p)) {
237 ret = 0;
238 break;
239 }
240 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
241 return ret; /* (sighing) "Often!" */
242}
243
244int is_current_pgrp_orphaned(void)
245{
246 int retval;
247
248 read_lock(&tasklist_lock);
249 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
250 read_unlock(&tasklist_lock);
251
252 return retval;
253}
254
255static int has_stopped_jobs(struct pid *pgrp)
256{
257 int retval = 0;
258 struct task_struct *p;
259
260 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
261 if (p->state != TASK_STOPPED)
262 continue;
263 retval = 1;
264 break;
265 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
266 return retval;
267}
268
269/**
270 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
271 *
272 * If a kernel thread is launched as a result of a system call, or if
273 * it ever exits, it should generally reparent itself to kthreadd so it
274 * isn't in the way of other processes and is correctly cleaned up on exit.
275 *
276 * The various task state such as scheduling policy and priority may have
277 * been inherited from a user process, so we reset them to sane values here.
278 *
279 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
280 */
281static void reparent_to_kthreadd(void)
282{
283 write_lock_irq(&tasklist_lock);
284
285 ptrace_unlink(current);
286 /* Reparent to init */
287 remove_parent(current);
288 current->real_parent = current->parent = kthreadd_task;
289 add_parent(current);
290
291 /* Set the exit signal to SIGCHLD so we signal init on exit */
292 current->exit_signal = SIGCHLD;
293
294 if (!has_rt_policy(current) && (task_nice(current) < 0))
295 set_user_nice(current, 0);
296 /* cpus_allowed? */
297 /* rt_priority? */
298 /* signals? */
299 security_task_reparent_to_init(current);
300 memcpy(current->signal->rlim, init_task.signal->rlim,
301 sizeof(current->signal->rlim));
302 atomic_inc(&(INIT_USER->__count));
303 write_unlock_irq(&tasklist_lock);
304 switch_uid(INIT_USER);
305}
306
307void __set_special_pids(pid_t session, pid_t pgrp)
308{
309 struct task_struct *curr = current->group_leader;
310
311 if (process_session(curr) != session) {
312 detach_pid(curr, PIDTYPE_SID);
313 set_signal_session(curr->signal, session);
314 attach_pid(curr, PIDTYPE_SID, find_pid(session));
315 }
316 if (process_group(curr) != pgrp) {
317 detach_pid(curr, PIDTYPE_PGID);
318 curr->signal->pgrp = pgrp;
319 attach_pid(curr, PIDTYPE_PGID, find_pid(pgrp));
320 }
321}
322
323static void set_special_pids(pid_t session, pid_t pgrp)
324{
325 write_lock_irq(&tasklist_lock);
326 __set_special_pids(session, pgrp);
327 write_unlock_irq(&tasklist_lock);
328}
329
330/*
331 * Let kernel threads use this to say that they
332 * allow a certain signal (since daemonize() will
333 * have disabled all of them by default).
334 */
335int allow_signal(int sig)
336{
337 if (!valid_signal(sig) || sig < 1)
338 return -EINVAL;
339
340 spin_lock_irq(&current->sighand->siglock);
341 sigdelset(&current->blocked, sig);
342 if (!current->mm) {
343 /* Kernel threads handle their own signals.
344 Let the signal code know it'll be handled, so
345 that they don't get converted to SIGKILL or
346 just silently dropped */
347 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
348 }
349 recalc_sigpending();
350 spin_unlock_irq(&current->sighand->siglock);
351 return 0;
352}
353
354EXPORT_SYMBOL(allow_signal);
355
356int disallow_signal(int sig)
357{
358 if (!valid_signal(sig) || sig < 1)
359 return -EINVAL;
360
361 spin_lock_irq(&current->sighand->siglock);
362 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
363 recalc_sigpending();
364 spin_unlock_irq(&current->sighand->siglock);
365 return 0;
366}
367
368EXPORT_SYMBOL(disallow_signal);
369
370/*
371 * Put all the gunge required to become a kernel thread without
372 * attached user resources in one place where it belongs.
373 */
374
375void daemonize(const char *name, ...)
376{
377 va_list args;
378 struct fs_struct *fs;
379 sigset_t blocked;
380
381 va_start(args, name);
382 vsnprintf(current->comm, sizeof(current->comm), name, args);
383 va_end(args);
384
385 /*
386 * If we were started as result of loading a module, close all of the
387 * user space pages. We don't need them, and if we didn't close them
388 * they would be locked into memory.
389 */
390 exit_mm(current);
391
392 set_special_pids(1, 1);
393 proc_clear_tty(current);
394
395 /* Block and flush all signals */
396 sigfillset(&blocked);
397 sigprocmask(SIG_BLOCK, &blocked, NULL);
398 flush_signals(current);
399
400 /* Become as one with the init task */
401
402 exit_fs(current); /* current->fs->count--; */
403 fs = init_task.fs;
404 current->fs = fs;
405 atomic_inc(&fs->count);
406
407 exit_task_namespaces(current);
408 current->nsproxy = init_task.nsproxy;
409 get_task_namespaces(current);
410
411 exit_files(current);
412 current->files = init_task.files;
413 atomic_inc(&current->files->count);
414
415 reparent_to_kthreadd();
416}
417
418EXPORT_SYMBOL(daemonize);
419
420static void close_files(struct files_struct * files)
421{
422 int i, j;
423 struct fdtable *fdt;
424
425 j = 0;
426
427 /*
428 * It is safe to dereference the fd table without RCU or
429 * ->file_lock because this is the last reference to the
430 * files structure.
431 */
432 fdt = files_fdtable(files);
433 for (;;) {
434 unsigned long set;
435 i = j * __NFDBITS;
436 if (i >= fdt->max_fds)
437 break;
438 set = fdt->open_fds->fds_bits[j++];
439 while (set) {
440 if (set & 1) {
441 struct file * file = xchg(&fdt->fd[i], NULL);
442 if (file) {
443 filp_close(file, files);
444 cond_resched();
445 }
446 }
447 i++;
448 set >>= 1;
449 }
450 }
451}
452
453struct files_struct *get_files_struct(struct task_struct *task)
454{
455 struct files_struct *files;
456
457 task_lock(task);
458 files = task->files;
459 if (files)
460 atomic_inc(&files->count);
461 task_unlock(task);
462
463 return files;
464}
465
466void fastcall put_files_struct(struct files_struct *files)
467{
468 struct fdtable *fdt;
469
470 if (atomic_dec_and_test(&files->count)) {
471 close_files(files);
472 /*
473 * Free the fd and fdset arrays if we expanded them.
474 * If the fdtable was embedded, pass files for freeing
475 * at the end of the RCU grace period. Otherwise,
476 * you can free files immediately.
477 */
478 fdt = files_fdtable(files);
479 if (fdt != &files->fdtab)
480 kmem_cache_free(files_cachep, files);
481 free_fdtable(fdt);
482 }
483}
484
485EXPORT_SYMBOL(put_files_struct);
486
487void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
488{
489 struct files_struct *old;
490
491 old = tsk->files;
492 task_lock(tsk);
493 tsk->files = files;
494 task_unlock(tsk);
495 put_files_struct(old);
496}
497EXPORT_SYMBOL(reset_files_struct);
498
499static inline void __exit_files(struct task_struct *tsk)
500{
501 struct files_struct * files = tsk->files;
502
503 if (files) {
504 task_lock(tsk);
505 tsk->files = NULL;
506 task_unlock(tsk);
507 put_files_struct(files);
508 }
509}
510
511void exit_files(struct task_struct *tsk)
512{
513 __exit_files(tsk);
514}
515
516static inline void __put_fs_struct(struct fs_struct *fs)
517{
518 /* No need to hold fs->lock if we are killing it */
519 if (atomic_dec_and_test(&fs->count)) {
520 dput(fs->root);
521 mntput(fs->rootmnt);
522 dput(fs->pwd);
523 mntput(fs->pwdmnt);
524 if (fs->altroot) {
525 dput(fs->altroot);
526 mntput(fs->altrootmnt);
527 }
528 kmem_cache_free(fs_cachep, fs);
529 }
530}
531
532void put_fs_struct(struct fs_struct *fs)
533{
534 __put_fs_struct(fs);
535}
536
537static inline void __exit_fs(struct task_struct *tsk)
538{
539 struct fs_struct * fs = tsk->fs;
540
541 if (fs) {
542 task_lock(tsk);
543 tsk->fs = NULL;
544 task_unlock(tsk);
545 __put_fs_struct(fs);
546 }
547}
548
549void exit_fs(struct task_struct *tsk)
550{
551 __exit_fs(tsk);
552}
553
554EXPORT_SYMBOL_GPL(exit_fs);
555
556/*
557 * Turn us into a lazy TLB process if we
558 * aren't already..
559 */
560static void exit_mm(struct task_struct * tsk)
561{
562 struct mm_struct *mm = tsk->mm;
563
564 mm_release(tsk, mm);
565 if (!mm)
566 return;
567 /*
568 * Serialize with any possible pending coredump.
569 * We must hold mmap_sem around checking core_waiters
570 * and clearing tsk->mm. The core-inducing thread
571 * will increment core_waiters for each thread in the
572 * group with ->mm != NULL.
573 */
574 down_read(&mm->mmap_sem);
575 if (mm->core_waiters) {
576 up_read(&mm->mmap_sem);
577 down_write(&mm->mmap_sem);
578 if (!--mm->core_waiters)
579 complete(mm->core_startup_done);
580 up_write(&mm->mmap_sem);
581
582 wait_for_completion(&mm->core_done);
583 down_read(&mm->mmap_sem);
584 }
585 atomic_inc(&mm->mm_count);
586 BUG_ON(mm != tsk->active_mm);
587 /* more a memory barrier than a real lock */
588 task_lock(tsk);
589 tsk->mm = NULL;
590 up_read(&mm->mmap_sem);
591 enter_lazy_tlb(mm, current);
592 task_unlock(tsk);
593 mmput(mm);
594}
595
596static inline void
597choose_new_parent(struct task_struct *p, struct task_struct *reaper)
598{
599 /*
600 * Make sure we're not reparenting to ourselves and that
601 * the parent is not a zombie.
602 */
603 BUG_ON(p == reaper || reaper->exit_state);
604 p->real_parent = reaper;
605}
606
607static void
608reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
609{
610 if (p->pdeath_signal)
611 /* We already hold the tasklist_lock here. */
612 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
613
614 /* Move the child from its dying parent to the new one. */
615 if (unlikely(traced)) {
616 /* Preserve ptrace links if someone else is tracing this child. */
617 list_del_init(&p->ptrace_list);
618 if (p->parent != p->real_parent)
619 list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
620 } else {
621 /* If this child is being traced, then we're the one tracing it
622 * anyway, so let go of it.
623 */
624 p->ptrace = 0;
625 remove_parent(p);
626 p->parent = p->real_parent;
627 add_parent(p);
628
629 if (p->state == TASK_TRACED) {
630 /*
631 * If it was at a trace stop, turn it into
632 * a normal stop since it's no longer being
633 * traced.
634 */
635 ptrace_untrace(p);
636 }
637 }
638
639 /* If this is a threaded reparent there is no need to
640 * notify anyone anything has happened.
641 */
642 if (p->real_parent->group_leader == father->group_leader)
643 return;
644
645 /* We don't want people slaying init. */
646 if (p->exit_signal != -1)
647 p->exit_signal = SIGCHLD;
648
649 /* If we'd notified the old parent about this child's death,
650 * also notify the new parent.
651 */
652 if (!traced && p->exit_state == EXIT_ZOMBIE &&
653 p->exit_signal != -1 && thread_group_empty(p))
654 do_notify_parent(p, p->exit_signal);
655
656 /*
657 * process group orphan check
658 * Case ii: Our child is in a different pgrp
659 * than we are, and it was the only connection
660 * outside, so the child pgrp is now orphaned.
661 */
662 if ((task_pgrp(p) != task_pgrp(father)) &&
663 (task_session(p) == task_session(father))) {
664 struct pid *pgrp = task_pgrp(p);
665
666 if (will_become_orphaned_pgrp(pgrp, NULL) &&
667 has_stopped_jobs(pgrp)) {
668 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
669 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
670 }
671 }
672}
673
674/*
675 * When we die, we re-parent all our children.
676 * Try to give them to another thread in our thread
677 * group, and if no such member exists, give it to
678 * the child reaper process (ie "init") in our pid
679 * space.
680 */
681static void
682forget_original_parent(struct task_struct *father, struct list_head *to_release)
683{
684 struct task_struct *p, *reaper = father;
685 struct list_head *_p, *_n;
686
687 do {
688 reaper = next_thread(reaper);
689 if (reaper == father) {
690 reaper = child_reaper(father);
691 break;
692 }
693 } while (reaper->exit_state);
694
695 /*
696 * There are only two places where our children can be:
697 *
698 * - in our child list
699 * - in our ptraced child list
700 *
701 * Search them and reparent children.
702 */
703 list_for_each_safe(_p, _n, &father->children) {
704 int ptrace;
705 p = list_entry(_p, struct task_struct, sibling);
706
707 ptrace = p->ptrace;
708
709 /* if father isn't the real parent, then ptrace must be enabled */
710 BUG_ON(father != p->real_parent && !ptrace);
711
712 if (father == p->real_parent) {
713 /* reparent with a reaper, real father it's us */
714 choose_new_parent(p, reaper);
715 reparent_thread(p, father, 0);
716 } else {
717 /* reparent ptraced task to its real parent */
718 __ptrace_unlink (p);
719 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
720 thread_group_empty(p))
721 do_notify_parent(p, p->exit_signal);
722 }
723
724 /*
725 * if the ptraced child is a zombie with exit_signal == -1
726 * we must collect it before we exit, or it will remain
727 * zombie forever since we prevented it from self-reap itself
728 * while it was being traced by us, to be able to see it in wait4.
729 */
730 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
731 list_add(&p->ptrace_list, to_release);
732 }
733 list_for_each_safe(_p, _n, &father->ptrace_children) {
734 p = list_entry(_p, struct task_struct, ptrace_list);
735 choose_new_parent(p, reaper);
736 reparent_thread(p, father, 1);
737 }
738}
739
740/*
741 * Send signals to all our closest relatives so that they know
742 * to properly mourn us..
743 */
744static void exit_notify(struct task_struct *tsk)
745{
746 int state;
747 struct task_struct *t;
748 struct list_head ptrace_dead, *_p, *_n;
749 struct pid *pgrp;
750
751 if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
752 && !thread_group_empty(tsk)) {
753 /*
754 * This occurs when there was a race between our exit
755 * syscall and a group signal choosing us as the one to
756 * wake up. It could be that we are the only thread
757 * alerted to check for pending signals, but another thread
758 * should be woken now to take the signal since we will not.
759 * Now we'll wake all the threads in the group just to make
760 * sure someone gets all the pending signals.
761 */
762 read_lock(&tasklist_lock);
763 spin_lock_irq(&tsk->sighand->siglock);
764 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
765 if (!signal_pending(t) && !(t->flags & PF_EXITING))
766 recalc_sigpending_and_wake(t);
767 spin_unlock_irq(&tsk->sighand->siglock);
768 read_unlock(&tasklist_lock);
769 }
770
771 write_lock_irq(&tasklist_lock);
772
773 /*
774 * This does two things:
775 *
776 * A. Make init inherit all the child processes
777 * B. Check to see if any process groups have become orphaned
778 * as a result of our exiting, and if they have any stopped
779 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
780 */
781
782 INIT_LIST_HEAD(&ptrace_dead);
783 forget_original_parent(tsk, &ptrace_dead);
784 BUG_ON(!list_empty(&tsk->children));
785 BUG_ON(!list_empty(&tsk->ptrace_children));
786
787 /*
788 * Check to see if any process groups have become orphaned
789 * as a result of our exiting, and if they have any stopped
790 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
791 *
792 * Case i: Our father is in a different pgrp than we are
793 * and we were the only connection outside, so our pgrp
794 * is about to become orphaned.
795 */
796
797 t = tsk->real_parent;
798
799 pgrp = task_pgrp(tsk);
800 if ((task_pgrp(t) != pgrp) &&
801 (task_session(t) == task_session(tsk)) &&
802 will_become_orphaned_pgrp(pgrp, tsk) &&
803 has_stopped_jobs(pgrp)) {
804 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
805 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
806 }
807
808 /* Let father know we died
809 *
810 * Thread signals are configurable, but you aren't going to use
811 * that to send signals to arbitary processes.
812 * That stops right now.
813 *
814 * If the parent exec id doesn't match the exec id we saved
815 * when we started then we know the parent has changed security
816 * domain.
817 *
818 * If our self_exec id doesn't match our parent_exec_id then
819 * we have changed execution domain as these two values started
820 * the same after a fork.
821 *
822 */
823
824 if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
825 ( tsk->parent_exec_id != t->self_exec_id ||
826 tsk->self_exec_id != tsk->parent_exec_id)
827 && !capable(CAP_KILL))
828 tsk->exit_signal = SIGCHLD;
829
830
831 /* If something other than our normal parent is ptracing us, then
832 * send it a SIGCHLD instead of honoring exit_signal. exit_signal
833 * only has special meaning to our real parent.
834 */
835 if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
836 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
837 do_notify_parent(tsk, signal);
838 } else if (tsk->ptrace) {
839 do_notify_parent(tsk, SIGCHLD);
840 }
841
842 state = EXIT_ZOMBIE;
843 if (tsk->exit_signal == -1 &&
844 (likely(tsk->ptrace == 0) ||
845 unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
846 state = EXIT_DEAD;
847 tsk->exit_state = state;
848
849 write_unlock_irq(&tasklist_lock);
850
851 list_for_each_safe(_p, _n, &ptrace_dead) {
852 list_del_init(_p);
853 t = list_entry(_p, struct task_struct, ptrace_list);
854 release_task(t);
855 }
856
857 /* If the process is dead, release it - nobody will wait for it */
858 if (state == EXIT_DEAD)
859 release_task(tsk);
860}
861
862fastcall NORET_TYPE void do_exit(long code)
863{
864 struct task_struct *tsk = current;
865 int group_dead;
866
867 profile_task_exit(tsk);
868
869 WARN_ON(atomic_read(&tsk->fs_excl));
870
871 if (unlikely(in_interrupt()))
872 panic("Aiee, killing interrupt handler!");
873 if (unlikely(!tsk->pid))
874 panic("Attempted to kill the idle task!");
875 if (unlikely(tsk == child_reaper(tsk))) {
876 if (tsk->nsproxy->pid_ns != &init_pid_ns)
877 tsk->nsproxy->pid_ns->child_reaper = init_pid_ns.child_reaper;
878 else
879 panic("Attempted to kill init!");
880 }
881
882
883 if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
884 current->ptrace_message = code;
885 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
886 }
887
888 /*
889 * We're taking recursive faults here in do_exit. Safest is to just
890 * leave this task alone and wait for reboot.
891 */
892 if (unlikely(tsk->flags & PF_EXITING)) {
893 printk(KERN_ALERT
894 "Fixing recursive fault but reboot is needed!\n");
895 /*
896 * We can do this unlocked here. The futex code uses
897 * this flag just to verify whether the pi state
898 * cleanup has been done or not. In the worst case it
899 * loops once more. We pretend that the cleanup was
900 * done as there is no way to return. Either the
901 * OWNER_DIED bit is set by now or we push the blocked
902 * task into the wait for ever nirwana as well.
903 */
904 tsk->flags |= PF_EXITPIDONE;
905 if (tsk->io_context)
906 exit_io_context();
907 set_current_state(TASK_UNINTERRUPTIBLE);
908 schedule();
909 }
910
911 /*
912 * tsk->flags are checked in the futex code to protect against
913 * an exiting task cleaning up the robust pi futexes.
914 */
915 spin_lock_irq(&tsk->pi_lock);
916 tsk->flags |= PF_EXITING;
917 spin_unlock_irq(&tsk->pi_lock);
918
919 if (unlikely(in_atomic()))
920 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
921 current->comm, current->pid,
922 preempt_count());
923
924 acct_update_integrals(tsk);
925 if (tsk->mm) {
926 update_hiwater_rss(tsk->mm);
927 update_hiwater_vm(tsk->mm);
928 }
929 group_dead = atomic_dec_and_test(&tsk->signal->live);
930 if (group_dead) {
931 hrtimer_cancel(&tsk->signal->real_timer);
932 exit_itimers(tsk->signal);
933 }
934 acct_collect(code, group_dead);
935 if (unlikely(tsk->robust_list))
936 exit_robust_list(tsk);
937#if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
938 if (unlikely(tsk->compat_robust_list))
939 compat_exit_robust_list(tsk);
940#endif
941 if (unlikely(tsk->audit_context))
942 audit_free(tsk);
943
944 taskstats_exit(tsk, group_dead);
945
946 exit_mm(tsk);
947
948 if (group_dead)
949 acct_process();
950 exit_sem(tsk);
951 __exit_files(tsk);
952 __exit_fs(tsk);
953 exit_thread();
954 cpuset_exit(tsk);
955 exit_keys(tsk);
956
957 if (group_dead && tsk->signal->leader)
958 disassociate_ctty(1);
959
960 module_put(task_thread_info(tsk)->exec_domain->module);
961 if (tsk->binfmt)
962 module_put(tsk->binfmt->module);
963
964 tsk->exit_code = code;
965 proc_exit_connector(tsk);
966 exit_task_namespaces(tsk);
967 exit_notify(tsk);
968#ifdef CONFIG_NUMA
969 mpol_free(tsk->mempolicy);
970 tsk->mempolicy = NULL;
971#endif
972 /*
973 * This must happen late, after the PID is not
974 * hashed anymore:
975 */
976 if (unlikely(!list_empty(&tsk->pi_state_list)))
977 exit_pi_state_list(tsk);
978 if (unlikely(current->pi_state_cache))
979 kfree(current->pi_state_cache);
980 /*
981 * Make sure we are holding no locks:
982 */
983 debug_check_no_locks_held(tsk);
984 /*
985 * We can do this unlocked here. The futex code uses this flag
986 * just to verify whether the pi state cleanup has been done
987 * or not. In the worst case it loops once more.
988 */
989 tsk->flags |= PF_EXITPIDONE;
990
991 if (tsk->io_context)
992 exit_io_context();
993
994 if (tsk->splice_pipe)
995 __free_pipe_info(tsk->splice_pipe);
996
997 preempt_disable();
998 /* causes final put_task_struct in finish_task_switch(). */
999 tsk->state = TASK_DEAD;
1000
1001 schedule();
1002 BUG();
1003 /* Avoid "noreturn function does return". */
1004 for (;;)
1005 cpu_relax(); /* For when BUG is null */
1006}
1007
1008EXPORT_SYMBOL_GPL(do_exit);
1009
1010NORET_TYPE void complete_and_exit(struct completion *comp, long code)
1011{
1012 if (comp)
1013 complete(comp);
1014
1015 do_exit(code);
1016}
1017
1018EXPORT_SYMBOL(complete_and_exit);
1019
1020asmlinkage long sys_exit(int error_code)
1021{
1022 do_exit((error_code&0xff)<<8);
1023}
1024
1025/*
1026 * Take down every thread in the group. This is called by fatal signals
1027 * as well as by sys_exit_group (below).
1028 */
1029NORET_TYPE void
1030do_group_exit(int exit_code)
1031{
1032 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1033
1034 if (current->signal->flags & SIGNAL_GROUP_EXIT)
1035 exit_code = current->signal->group_exit_code;
1036 else if (!thread_group_empty(current)) {
1037 struct signal_struct *const sig = current->signal;
1038 struct sighand_struct *const sighand = current->sighand;
1039 spin_lock_irq(&sighand->siglock);
1040 if (sig->flags & SIGNAL_GROUP_EXIT)
1041 /* Another thread got here before we took the lock. */
1042 exit_code = sig->group_exit_code;
1043 else {
1044 sig->group_exit_code = exit_code;
1045 zap_other_threads(current);
1046 }
1047 spin_unlock_irq(&sighand->siglock);
1048 }
1049
1050 do_exit(exit_code);
1051 /* NOTREACHED */
1052}
1053
1054/*
1055 * this kills every thread in the thread group. Note that any externally
1056 * wait4()-ing process will get the correct exit code - even if this
1057 * thread is not the thread group leader.
1058 */
1059asmlinkage void sys_exit_group(int error_code)
1060{
1061 do_group_exit((error_code & 0xff) << 8);
1062}
1063
1064static int eligible_child(pid_t pid, int options, struct task_struct *p)
1065{
1066 int err;
1067
1068 if (pid > 0) {
1069 if (p->pid != pid)
1070 return 0;
1071 } else if (!pid) {
1072 if (process_group(p) != process_group(current))
1073 return 0;
1074 } else if (pid != -1) {
1075 if (process_group(p) != -pid)
1076 return 0;
1077 }
1078
1079 /*
1080 * Do not consider detached threads that are
1081 * not ptraced:
1082 */
1083 if (p->exit_signal == -1 && !p->ptrace)
1084 return 0;
1085
1086 /* Wait for all children (clone and not) if __WALL is set;
1087 * otherwise, wait for clone children *only* if __WCLONE is
1088 * set; otherwise, wait for non-clone children *only*. (Note:
1089 * A "clone" child here is one that reports to its parent
1090 * using a signal other than SIGCHLD.) */
1091 if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1092 && !(options & __WALL))
1093 return 0;
1094 /*
1095 * Do not consider thread group leaders that are
1096 * in a non-empty thread group:
1097 */
1098 if (delay_group_leader(p))
1099 return 2;
1100
1101 err = security_task_wait(p);
1102 if (err)
1103 return err;
1104
1105 return 1;
1106}
1107
1108static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1109 int why, int status,
1110 struct siginfo __user *infop,
1111 struct rusage __user *rusagep)
1112{
1113 int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1114
1115 put_task_struct(p);
1116 if (!retval)
1117 retval = put_user(SIGCHLD, &infop->si_signo);
1118 if (!retval)
1119 retval = put_user(0, &infop->si_errno);
1120 if (!retval)
1121 retval = put_user((short)why, &infop->si_code);
1122 if (!retval)
1123 retval = put_user(pid, &infop->si_pid);
1124 if (!retval)
1125 retval = put_user(uid, &infop->si_uid);
1126 if (!retval)
1127 retval = put_user(status, &infop->si_status);
1128 if (!retval)
1129 retval = pid;
1130 return retval;
1131}
1132
1133/*
1134 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1135 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1136 * the lock and this task is uninteresting. If we return nonzero, we have
1137 * released the lock and the system call should return.
1138 */
1139static int wait_task_zombie(struct task_struct *p, int noreap,
1140 struct siginfo __user *infop,
1141 int __user *stat_addr, struct rusage __user *ru)
1142{
1143 unsigned long state;
1144 int retval;
1145 int status;
1146
1147 if (unlikely(noreap)) {
1148 pid_t pid = p->pid;
1149 uid_t uid = p->uid;
1150 int exit_code = p->exit_code;
1151 int why, status;
1152
1153 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1154 return 0;
1155 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1156 return 0;
1157 get_task_struct(p);
1158 read_unlock(&tasklist_lock);
1159 if ((exit_code & 0x7f) == 0) {
1160 why = CLD_EXITED;
1161 status = exit_code >> 8;
1162 } else {
1163 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1164 status = exit_code & 0x7f;
1165 }
1166 return wait_noreap_copyout(p, pid, uid, why,
1167 status, infop, ru);
1168 }
1169
1170 /*
1171 * Try to move the task's state to DEAD
1172 * only one thread is allowed to do this:
1173 */
1174 state = xchg(&p->exit_state, EXIT_DEAD);
1175 if (state != EXIT_ZOMBIE) {
1176 BUG_ON(state != EXIT_DEAD);
1177 return 0;
1178 }
1179 if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1180 /*
1181 * This can only happen in a race with a ptraced thread
1182 * dying on another processor.
1183 */
1184 return 0;
1185 }
1186
1187 if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1188 struct signal_struct *psig;
1189 struct signal_struct *sig;
1190
1191 /*
1192 * The resource counters for the group leader are in its
1193 * own task_struct. Those for dead threads in the group
1194 * are in its signal_struct, as are those for the child
1195 * processes it has previously reaped. All these
1196 * accumulate in the parent's signal_struct c* fields.
1197 *
1198 * We don't bother to take a lock here to protect these
1199 * p->signal fields, because they are only touched by
1200 * __exit_signal, which runs with tasklist_lock
1201 * write-locked anyway, and so is excluded here. We do
1202 * need to protect the access to p->parent->signal fields,
1203 * as other threads in the parent group can be right
1204 * here reaping other children at the same time.
1205 */
1206 spin_lock_irq(&p->parent->sighand->siglock);
1207 psig = p->parent->signal;
1208 sig = p->signal;
1209 psig->cutime =
1210 cputime_add(psig->cutime,
1211 cputime_add(p->utime,
1212 cputime_add(sig->utime,
1213 sig->cutime)));
1214 psig->cstime =
1215 cputime_add(psig->cstime,
1216 cputime_add(p->stime,
1217 cputime_add(sig->stime,
1218 sig->cstime)));
1219 psig->cmin_flt +=
1220 p->min_flt + sig->min_flt + sig->cmin_flt;
1221 psig->cmaj_flt +=
1222 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1223 psig->cnvcsw +=
1224 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1225 psig->cnivcsw +=
1226 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1227 psig->cinblock +=
1228 task_io_get_inblock(p) +
1229 sig->inblock + sig->cinblock;
1230 psig->coublock +=
1231 task_io_get_oublock(p) +
1232 sig->oublock + sig->coublock;
1233 spin_unlock_irq(&p->parent->sighand->siglock);
1234 }
1235
1236 /*
1237 * Now we are sure this task is interesting, and no other
1238 * thread can reap it because we set its state to EXIT_DEAD.
1239 */
1240 read_unlock(&tasklist_lock);
1241
1242 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1243 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1244 ? p->signal->group_exit_code : p->exit_code;
1245 if (!retval && stat_addr)
1246 retval = put_user(status, stat_addr);
1247 if (!retval && infop)
1248 retval = put_user(SIGCHLD, &infop->si_signo);
1249 if (!retval && infop)
1250 retval = put_user(0, &infop->si_errno);
1251 if (!retval && infop) {
1252 int why;
1253
1254 if ((status & 0x7f) == 0) {
1255 why = CLD_EXITED;
1256 status >>= 8;
1257 } else {
1258 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1259 status &= 0x7f;
1260 }
1261 retval = put_user((short)why, &infop->si_code);
1262 if (!retval)
1263 retval = put_user(status, &infop->si_status);
1264 }
1265 if (!retval && infop)
1266 retval = put_user(p->pid, &infop->si_pid);
1267 if (!retval && infop)
1268 retval = put_user(p->uid, &infop->si_uid);
1269 if (retval) {
1270 // TODO: is this safe?
1271 p->exit_state = EXIT_ZOMBIE;
1272 return retval;
1273 }
1274 retval = p->pid;
1275 if (p->real_parent != p->parent) {
1276 write_lock_irq(&tasklist_lock);
1277 /* Double-check with lock held. */
1278 if (p->real_parent != p->parent) {
1279 __ptrace_unlink(p);
1280 // TODO: is this safe?
1281 p->exit_state = EXIT_ZOMBIE;
1282 /*
1283 * If this is not a detached task, notify the parent.
1284 * If it's still not detached after that, don't release
1285 * it now.
1286 */
1287 if (p->exit_signal != -1) {
1288 do_notify_parent(p, p->exit_signal);
1289 if (p->exit_signal != -1)
1290 p = NULL;
1291 }
1292 }
1293 write_unlock_irq(&tasklist_lock);
1294 }
1295 if (p != NULL)
1296 release_task(p);
1297 BUG_ON(!retval);
1298 return retval;
1299}
1300
1301/*
1302 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1303 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1304 * the lock and this task is uninteresting. If we return nonzero, we have
1305 * released the lock and the system call should return.
1306 */
1307static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1308 int noreap, struct siginfo __user *infop,
1309 int __user *stat_addr, struct rusage __user *ru)
1310{
1311 int retval, exit_code;
1312
1313 if (!p->exit_code)
1314 return 0;
1315 if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1316 p->signal && p->signal->group_stop_count > 0)
1317 /*
1318 * A group stop is in progress and this is the group leader.
1319 * We won't report until all threads have stopped.
1320 */
1321 return 0;
1322
1323 /*
1324 * Now we are pretty sure this task is interesting.
1325 * Make sure it doesn't get reaped out from under us while we
1326 * give up the lock and then examine it below. We don't want to
1327 * keep holding onto the tasklist_lock while we call getrusage and
1328 * possibly take page faults for user memory.
1329 */
1330 get_task_struct(p);
1331 read_unlock(&tasklist_lock);
1332
1333 if (unlikely(noreap)) {
1334 pid_t pid = p->pid;
1335 uid_t uid = p->uid;
1336 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1337
1338 exit_code = p->exit_code;
1339 if (unlikely(!exit_code) ||
1340 unlikely(p->state & TASK_TRACED))
1341 goto bail_ref;
1342 return wait_noreap_copyout(p, pid, uid,
1343 why, (exit_code << 8) | 0x7f,
1344 infop, ru);
1345 }
1346
1347 write_lock_irq(&tasklist_lock);
1348
1349 /*
1350 * This uses xchg to be atomic with the thread resuming and setting
1351 * it. It must also be done with the write lock held to prevent a
1352 * race with the EXIT_ZOMBIE case.
1353 */
1354 exit_code = xchg(&p->exit_code, 0);
1355 if (unlikely(p->exit_state)) {
1356 /*
1357 * The task resumed and then died. Let the next iteration
1358 * catch it in EXIT_ZOMBIE. Note that exit_code might
1359 * already be zero here if it resumed and did _exit(0).
1360 * The task itself is dead and won't touch exit_code again;
1361 * other processors in this function are locked out.
1362 */
1363 p->exit_code = exit_code;
1364 exit_code = 0;
1365 }
1366 if (unlikely(exit_code == 0)) {
1367 /*
1368 * Another thread in this function got to it first, or it
1369 * resumed, or it resumed and then died.
1370 */
1371 write_unlock_irq(&tasklist_lock);
1372bail_ref:
1373 put_task_struct(p);
1374 /*
1375 * We are returning to the wait loop without having successfully
1376 * removed the process and having released the lock. We cannot
1377 * continue, since the "p" task pointer is potentially stale.
1378 *
1379 * Return -EAGAIN, and do_wait() will restart the loop from the
1380 * beginning. Do _not_ re-acquire the lock.
1381 */
1382 return -EAGAIN;
1383 }
1384
1385 /* move to end of parent's list to avoid starvation */
1386 remove_parent(p);
1387 add_parent(p);
1388
1389 write_unlock_irq(&tasklist_lock);
1390
1391 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1392 if (!retval && stat_addr)
1393 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1394 if (!retval && infop)
1395 retval = put_user(SIGCHLD, &infop->si_signo);
1396 if (!retval && infop)
1397 retval = put_user(0, &infop->si_errno);
1398 if (!retval && infop)
1399 retval = put_user((short)((p->ptrace & PT_PTRACED)
1400 ? CLD_TRAPPED : CLD_STOPPED),
1401 &infop->si_code);
1402 if (!retval && infop)
1403 retval = put_user(exit_code, &infop->si_status);
1404 if (!retval && infop)
1405 retval = put_user(p->pid, &infop->si_pid);
1406 if (!retval && infop)
1407 retval = put_user(p->uid, &infop->si_uid);
1408 if (!retval)
1409 retval = p->pid;
1410 put_task_struct(p);
1411
1412 BUG_ON(!retval);
1413 return retval;
1414}
1415
1416/*
1417 * Handle do_wait work for one task in a live, non-stopped state.
1418 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1419 * the lock and this task is uninteresting. If we return nonzero, we have
1420 * released the lock and the system call should return.
1421 */
1422static int wait_task_continued(struct task_struct *p, int noreap,
1423 struct siginfo __user *infop,
1424 int __user *stat_addr, struct rusage __user *ru)
1425{
1426 int retval;
1427 pid_t pid;
1428 uid_t uid;
1429
1430 if (unlikely(!p->signal))
1431 return 0;
1432
1433 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1434 return 0;
1435
1436 spin_lock_irq(&p->sighand->siglock);
1437 /* Re-check with the lock held. */
1438 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1439 spin_unlock_irq(&p->sighand->siglock);
1440 return 0;
1441 }
1442 if (!noreap)
1443 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1444 spin_unlock_irq(&p->sighand->siglock);
1445
1446 pid = p->pid;
1447 uid = p->uid;
1448 get_task_struct(p);
1449 read_unlock(&tasklist_lock);
1450
1451 if (!infop) {
1452 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1453 put_task_struct(p);
1454 if (!retval && stat_addr)
1455 retval = put_user(0xffff, stat_addr);
1456 if (!retval)
1457 retval = p->pid;
1458 } else {
1459 retval = wait_noreap_copyout(p, pid, uid,
1460 CLD_CONTINUED, SIGCONT,
1461 infop, ru);
1462 BUG_ON(retval == 0);
1463 }
1464
1465 return retval;
1466}
1467
1468
1469static inline int my_ptrace_child(struct task_struct *p)
1470{
1471 if (!(p->ptrace & PT_PTRACED))
1472 return 0;
1473 if (!(p->ptrace & PT_ATTACHED))
1474 return 1;
1475 /*
1476 * This child was PTRACE_ATTACH'd. We should be seeing it only if
1477 * we are the attacher. If we are the real parent, this is a race
1478 * inside ptrace_attach. It is waiting for the tasklist_lock,
1479 * which we have to switch the parent links, but has already set
1480 * the flags in p->ptrace.
1481 */
1482 return (p->parent != p->real_parent);
1483}
1484
1485static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1486 int __user *stat_addr, struct rusage __user *ru)
1487{
1488 DECLARE_WAITQUEUE(wait, current);
1489 struct task_struct *tsk;
1490 int flag, retval;
1491 int allowed, denied;
1492
1493 add_wait_queue(&current->signal->wait_chldexit,&wait);
1494repeat:
1495 /*
1496 * We will set this flag if we see any child that might later
1497 * match our criteria, even if we are not able to reap it yet.
1498 */
1499 flag = 0;
1500 allowed = denied = 0;
1501 current->state = TASK_INTERRUPTIBLE;
1502 read_lock(&tasklist_lock);
1503 tsk = current;
1504 do {
1505 struct task_struct *p;
1506 struct list_head *_p;
1507 int ret;
1508
1509 list_for_each(_p,&tsk->children) {
1510 p = list_entry(_p, struct task_struct, sibling);
1511
1512 ret = eligible_child(pid, options, p);
1513 if (!ret)
1514 continue;
1515
1516 if (unlikely(ret < 0)) {
1517 denied = ret;
1518 continue;
1519 }
1520 allowed = 1;
1521
1522 switch (p->state) {
1523 case TASK_TRACED:
1524 /*
1525 * When we hit the race with PTRACE_ATTACH,
1526 * we will not report this child. But the
1527 * race means it has not yet been moved to
1528 * our ptrace_children list, so we need to
1529 * set the flag here to avoid a spurious ECHILD
1530 * when the race happens with the only child.
1531 */
1532 flag = 1;
1533 if (!my_ptrace_child(p))
1534 continue;
1535 /*FALLTHROUGH*/
1536 case TASK_STOPPED:
1537 /*
1538 * It's stopped now, so it might later
1539 * continue, exit, or stop again.
1540 */
1541 flag = 1;
1542 if (!(options & WUNTRACED) &&
1543 !my_ptrace_child(p))
1544 continue;
1545 retval = wait_task_stopped(p, ret == 2,
1546 (options & WNOWAIT),
1547 infop,
1548 stat_addr, ru);
1549 if (retval == -EAGAIN)
1550 goto repeat;
1551 if (retval != 0) /* He released the lock. */
1552 goto end;
1553 break;
1554 default:
1555 // case EXIT_DEAD:
1556 if (p->exit_state == EXIT_DEAD)
1557 continue;
1558 // case EXIT_ZOMBIE:
1559 if (p->exit_state == EXIT_ZOMBIE) {
1560 /*
1561 * Eligible but we cannot release
1562 * it yet:
1563 */
1564 if (ret == 2)
1565 goto check_continued;
1566 if (!likely(options & WEXITED))
1567 continue;
1568 retval = wait_task_zombie(
1569 p, (options & WNOWAIT),
1570 infop, stat_addr, ru);
1571 /* He released the lock. */
1572 if (retval != 0)
1573 goto end;
1574 break;
1575 }
1576check_continued:
1577 /*
1578 * It's running now, so it might later
1579 * exit, stop, or stop and then continue.
1580 */
1581 flag = 1;
1582 if (!unlikely(options & WCONTINUED))
1583 continue;
1584 retval = wait_task_continued(
1585 p, (options & WNOWAIT),
1586 infop, stat_addr, ru);
1587 if (retval != 0) /* He released the lock. */
1588 goto end;
1589 break;
1590 }
1591 }
1592 if (!flag) {
1593 list_for_each(_p, &tsk->ptrace_children) {
1594 p = list_entry(_p, struct task_struct,
1595 ptrace_list);
1596 if (!eligible_child(pid, options, p))
1597 continue;
1598 flag = 1;
1599 break;
1600 }
1601 }
1602 if (options & __WNOTHREAD)
1603 break;
1604 tsk = next_thread(tsk);
1605 BUG_ON(tsk->signal != current->signal);
1606 } while (tsk != current);
1607
1608 read_unlock(&tasklist_lock);
1609 if (flag) {
1610 retval = 0;
1611 if (options & WNOHANG)
1612 goto end;
1613 retval = -ERESTARTSYS;
1614 if (signal_pending(current))
1615 goto end;
1616 schedule();
1617 goto repeat;
1618 }
1619 retval = -ECHILD;
1620 if (unlikely(denied) && !allowed)
1621 retval = denied;
1622end:
1623 current->state = TASK_RUNNING;
1624 remove_wait_queue(&current->signal->wait_chldexit,&wait);
1625 if (infop) {
1626 if (retval > 0)
1627 retval = 0;
1628 else {
1629 /*
1630 * For a WNOHANG return, clear out all the fields
1631 * we would set so the user can easily tell the
1632 * difference.
1633 */
1634 if (!retval)
1635 retval = put_user(0, &infop->si_signo);
1636 if (!retval)
1637 retval = put_user(0, &infop->si_errno);
1638 if (!retval)
1639 retval = put_user(0, &infop->si_code);
1640 if (!retval)
1641 retval = put_user(0, &infop->si_pid);
1642 if (!retval)
1643 retval = put_user(0, &infop->si_uid);
1644 if (!retval)
1645 retval = put_user(0, &infop->si_status);
1646 }
1647 }
1648 return retval;
1649}
1650
1651asmlinkage long sys_waitid(int which, pid_t pid,
1652 struct siginfo __user *infop, int options,
1653 struct rusage __user *ru)
1654{
1655 long ret;
1656
1657 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1658 return -EINVAL;
1659 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1660 return -EINVAL;
1661
1662 switch (which) {
1663 case P_ALL:
1664 pid = -1;
1665 break;
1666 case P_PID:
1667 if (pid <= 0)
1668 return -EINVAL;
1669 break;
1670 case P_PGID:
1671 if (pid <= 0)
1672 return -EINVAL;
1673 pid = -pid;
1674 break;
1675 default:
1676 return -EINVAL;
1677 }
1678
1679 ret = do_wait(pid, options, infop, NULL, ru);
1680
1681 /* avoid REGPARM breakage on x86: */
1682 prevent_tail_call(ret);
1683 return ret;
1684}
1685
1686asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1687 int options, struct rusage __user *ru)
1688{
1689 long ret;
1690
1691 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1692 __WNOTHREAD|__WCLONE|__WALL))
1693 return -EINVAL;
1694 ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1695
1696 /* avoid REGPARM breakage on x86: */
1697 prevent_tail_call(ret);
1698 return ret;
1699}
1700
1701#ifdef __ARCH_WANT_SYS_WAITPID
1702
1703/*
1704 * sys_waitpid() remains for compatibility. waitpid() should be
1705 * implemented by calling sys_wait4() from libc.a.
1706 */
1707asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1708{
1709 return sys_wait4(pid, stat_addr, options, NULL);
1710}
1711
1712#endif