projects/linux·blob v2.6.23 · refs

1738 lines · 43.8 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/mount.h>
28#include <linux/proc_fs.h>
29#include <linux/kthread.h>
30#include <linux/mempolicy.h>
31#include <linux/taskstats_kern.h>
32#include <linux/delayacct.h>
33#include <linux/freezer.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#include <linux/freezer.h>
48
49#include <asm/uaccess.h>
50#include <asm/unistd.h>
51#include <asm/pgtable.h>
52#include <asm/mmu_context.h>
53
54extern void sem_exit (void);
55
56static void exit_mm(struct task_struct * tsk);
57
58static void __unhash_process(struct task_struct *p)
59{
60 nr_threads--;
61 detach_pid(p, PIDTYPE_PID);
62 if (thread_group_leader(p)) {
63 detach_pid(p, PIDTYPE_PGID);
64 detach_pid(p, PIDTYPE_SID);
65
66 list_del_rcu(&p->tasks);
67 __get_cpu_var(process_counts)--;
68 }
69 list_del_rcu(&p->thread_group);
70 remove_parent(p);
71}
72
73/*
74 * This function expects the tasklist_lock write-locked.
75 */
76static void __exit_signal(struct task_struct *tsk)
77{
78 struct signal_struct *sig = tsk->signal;
79 struct sighand_struct *sighand;
80
81 BUG_ON(!sig);
82 BUG_ON(!atomic_read(&sig->count));
83
84 rcu_read_lock();
85 sighand = rcu_dereference(tsk->sighand);
86 spin_lock(&sighand->siglock);
87
88 posix_cpu_timers_exit(tsk);
89 if (atomic_dec_and_test(&sig->count))
90 posix_cpu_timers_exit_group(tsk);
91 else {
92 /*
93 * If there is any task waiting for the group exit
94 * then notify it:
95 */
96 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
97 wake_up_process(sig->group_exit_task);
98 sig->group_exit_task = NULL;
99 }
100 if (tsk == sig->curr_target)
101 sig->curr_target = next_thread(tsk);
102 /*
103 * Accumulate here the counters for all threads but the
104 * group leader as they die, so they can be added into
105 * the process-wide totals when those are taken.
106 * The group leader stays around as a zombie as long
107 * as there are other threads. When it gets reaped,
108 * the exit.c code will add its counts into these totals.
109 * We won't ever get here for the group leader, since it
110 * will have been the last reference on the signal_struct.
111 */
112 sig->utime = cputime_add(sig->utime, tsk->utime);
113 sig->stime = cputime_add(sig->stime, tsk->stime);
114 sig->min_flt += tsk->min_flt;
115 sig->maj_flt += tsk->maj_flt;
116 sig->nvcsw += tsk->nvcsw;
117 sig->nivcsw += tsk->nivcsw;
118 sig->inblock += task_io_get_inblock(tsk);
119 sig->oublock += task_io_get_oublock(tsk);
120 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
121 sig = NULL; /* Marker for below. */
122 }
123
124 __unhash_process(tsk);
125
126 tsk->signal = NULL;
127 tsk->sighand = NULL;
128 spin_unlock(&sighand->siglock);
129 rcu_read_unlock();
130
131 __cleanup_sighand(sighand);
132 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
133 flush_sigqueue(&tsk->pending);
134 if (sig) {
135 flush_sigqueue(&sig->shared_pending);
136 taskstats_tgid_free(sig);
137 __cleanup_signal(sig);
138 }
139}
140
141static void delayed_put_task_struct(struct rcu_head *rhp)
142{
143 put_task_struct(container_of(rhp, struct task_struct, rcu));
144}
145
146void release_task(struct task_struct * p)
147{
148 struct task_struct *leader;
149 int zap_leader;
150repeat:
151 atomic_dec(&p->user->processes);
152 write_lock_irq(&tasklist_lock);
153 ptrace_unlink(p);
154 BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
155 __exit_signal(p);
156
157 /*
158 * If we are the last non-leader member of the thread
159 * group, and the leader is zombie, then notify the
160 * group leader's parent process. (if it wants notification.)
161 */
162 zap_leader = 0;
163 leader = p->group_leader;
164 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
165 BUG_ON(leader->exit_signal == -1);
166 do_notify_parent(leader, leader->exit_signal);
167 /*
168 * If we were the last child thread and the leader has
169 * exited already, and the leader's parent ignores SIGCHLD,
170 * then we are the one who should release the leader.
171 *
172 * do_notify_parent() will have marked it self-reaping in
173 * that case.
174 */
175 zap_leader = (leader->exit_signal == -1);
176 }
177
178 write_unlock_irq(&tasklist_lock);
179 proc_flush_task(p);
180 release_thread(p);
181 call_rcu(&p->rcu, delayed_put_task_struct);
182
183 p = leader;
184 if (unlikely(zap_leader))
185 goto repeat;
186}
187
188/*
189 * This checks not only the pgrp, but falls back on the pid if no
190 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
191 * without this...
192 *
193 * The caller must hold rcu lock or the tasklist lock.
194 */
195struct pid *session_of_pgrp(struct pid *pgrp)
196{
197 struct task_struct *p;
198 struct pid *sid = NULL;
199
200 p = pid_task(pgrp, PIDTYPE_PGID);
201 if (p == NULL)
202 p = pid_task(pgrp, PIDTYPE_PID);
203 if (p != NULL)
204 sid = task_session(p);
205
206 return sid;
207}
208
209/*
210 * Determine if a process group is "orphaned", according to the POSIX
211 * definition in 2.2.2.52. Orphaned process groups are not to be affected
212 * by terminal-generated stop signals. Newly orphaned process groups are
213 * to receive a SIGHUP and a SIGCONT.
214 *
215 * "I ask you, have you ever known what it is to be an orphan?"
216 */
217static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
218{
219 struct task_struct *p;
220 int ret = 1;
221
222 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
223 if (p == ignored_task
224 || p->exit_state
225 || is_init(p->real_parent))
226 continue;
227 if (task_pgrp(p->real_parent) != pgrp &&
228 task_session(p->real_parent) == task_session(p)) {
229 ret = 0;
230 break;
231 }
232 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
233 return ret; /* (sighing) "Often!" */
234}
235
236int is_current_pgrp_orphaned(void)
237{
238 int retval;
239
240 read_lock(&tasklist_lock);
241 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
242 read_unlock(&tasklist_lock);
243
244 return retval;
245}
246
247static int has_stopped_jobs(struct pid *pgrp)
248{
249 int retval = 0;
250 struct task_struct *p;
251
252 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
253 if (p->state != TASK_STOPPED)
254 continue;
255 retval = 1;
256 break;
257 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
258 return retval;
259}
260
261/**
262 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
263 *
264 * If a kernel thread is launched as a result of a system call, or if
265 * it ever exits, it should generally reparent itself to kthreadd so it
266 * isn't in the way of other processes and is correctly cleaned up on exit.
267 *
268 * The various task state such as scheduling policy and priority may have
269 * been inherited from a user process, so we reset them to sane values here.
270 *
271 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
272 */
273static void reparent_to_kthreadd(void)
274{
275 write_lock_irq(&tasklist_lock);
276
277 ptrace_unlink(current);
278 /* Reparent to init */
279 remove_parent(current);
280 current->real_parent = current->parent = kthreadd_task;
281 add_parent(current);
282
283 /* Set the exit signal to SIGCHLD so we signal init on exit */
284 current->exit_signal = SIGCHLD;
285
286 if (task_nice(current) < 0)
287 set_user_nice(current, 0);
288 /* cpus_allowed? */
289 /* rt_priority? */
290 /* signals? */
291 security_task_reparent_to_init(current);
292 memcpy(current->signal->rlim, init_task.signal->rlim,
293 sizeof(current->signal->rlim));
294 atomic_inc(&(INIT_USER->__count));
295 write_unlock_irq(&tasklist_lock);
296 switch_uid(INIT_USER);
297}
298
299void __set_special_pids(pid_t session, pid_t pgrp)
300{
301 struct task_struct *curr = current->group_leader;
302
303 if (process_session(curr) != session) {
304 detach_pid(curr, PIDTYPE_SID);
305 set_signal_session(curr->signal, session);
306 attach_pid(curr, PIDTYPE_SID, find_pid(session));
307 }
308 if (process_group(curr) != pgrp) {
309 detach_pid(curr, PIDTYPE_PGID);
310 curr->signal->pgrp = pgrp;
311 attach_pid(curr, PIDTYPE_PGID, find_pid(pgrp));
312 }
313}
314
315static void set_special_pids(pid_t session, pid_t pgrp)
316{
317 write_lock_irq(&tasklist_lock);
318 __set_special_pids(session, pgrp);
319 write_unlock_irq(&tasklist_lock);
320}
321
322/*
323 * Let kernel threads use this to say that they
324 * allow a certain signal (since daemonize() will
325 * have disabled all of them by default).
326 */
327int allow_signal(int sig)
328{
329 if (!valid_signal(sig) || sig < 1)
330 return -EINVAL;
331
332 spin_lock_irq(&current->sighand->siglock);
333 sigdelset(&current->blocked, sig);
334 if (!current->mm) {
335 /* Kernel threads handle their own signals.
336 Let the signal code know it'll be handled, so
337 that they don't get converted to SIGKILL or
338 just silently dropped */
339 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
340 }
341 recalc_sigpending();
342 spin_unlock_irq(&current->sighand->siglock);
343 return 0;
344}
345
346EXPORT_SYMBOL(allow_signal);
347
348int disallow_signal(int sig)
349{
350 if (!valid_signal(sig) || sig < 1)
351 return -EINVAL;
352
353 spin_lock_irq(&current->sighand->siglock);
354 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
355 recalc_sigpending();
356 spin_unlock_irq(&current->sighand->siglock);
357 return 0;
358}
359
360EXPORT_SYMBOL(disallow_signal);
361
362/*
363 * Put all the gunge required to become a kernel thread without
364 * attached user resources in one place where it belongs.
365 */
366
367void daemonize(const char *name, ...)
368{
369 va_list args;
370 struct fs_struct *fs;
371 sigset_t blocked;
372
373 va_start(args, name);
374 vsnprintf(current->comm, sizeof(current->comm), name, args);
375 va_end(args);
376
377 /*
378 * If we were started as result of loading a module, close all of the
379 * user space pages. We don't need them, and if we didn't close them
380 * they would be locked into memory.
381 */
382 exit_mm(current);
383 /*
384 * We don't want to have TIF_FREEZE set if the system-wide hibernation
385 * or suspend transition begins right now.
386 */
387 current->flags |= PF_NOFREEZE;
388
389 set_special_pids(1, 1);
390 proc_clear_tty(current);
391
392 /* Block and flush all signals */
393 sigfillset(&blocked);
394 sigprocmask(SIG_BLOCK, &blocked, NULL);
395 flush_signals(current);
396
397 /* Become as one with the init task */
398
399 exit_fs(current); /* current->fs->count--; */
400 fs = init_task.fs;
401 current->fs = fs;
402 atomic_inc(&fs->count);
403
404 exit_task_namespaces(current);
405 current->nsproxy = init_task.nsproxy;
406 get_task_namespaces(current);
407
408 exit_files(current);
409 current->files = init_task.files;
410 atomic_inc(&current->files->count);
411
412 reparent_to_kthreadd();
413}
414
415EXPORT_SYMBOL(daemonize);
416
417static void close_files(struct files_struct * files)
418{
419 int i, j;
420 struct fdtable *fdt;
421
422 j = 0;
423
424 /*
425 * It is safe to dereference the fd table without RCU or
426 * ->file_lock because this is the last reference to the
427 * files structure.
428 */
429 fdt = files_fdtable(files);
430 for (;;) {
431 unsigned long set;
432 i = j * __NFDBITS;
433 if (i >= fdt->max_fds)
434 break;
435 set = fdt->open_fds->fds_bits[j++];
436 while (set) {
437 if (set & 1) {
438 struct file * file = xchg(&fdt->fd[i], NULL);
439 if (file) {
440 filp_close(file, files);
441 cond_resched();
442 }
443 }
444 i++;
445 set >>= 1;
446 }
447 }
448}
449
450struct files_struct *get_files_struct(struct task_struct *task)
451{
452 struct files_struct *files;
453
454 task_lock(task);
455 files = task->files;
456 if (files)
457 atomic_inc(&files->count);
458 task_unlock(task);
459
460 return files;
461}
462
463void fastcall put_files_struct(struct files_struct *files)
464{
465 struct fdtable *fdt;
466
467 if (atomic_dec_and_test(&files->count)) {
468 close_files(files);
469 /*
470 * Free the fd and fdset arrays if we expanded them.
471 * If the fdtable was embedded, pass files for freeing
472 * at the end of the RCU grace period. Otherwise,
473 * you can free files immediately.
474 */
475 fdt = files_fdtable(files);
476 if (fdt != &files->fdtab)
477 kmem_cache_free(files_cachep, files);
478 free_fdtable(fdt);
479 }
480}
481
482EXPORT_SYMBOL(put_files_struct);
483
484void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
485{
486 struct files_struct *old;
487
488 old = tsk->files;
489 task_lock(tsk);
490 tsk->files = files;
491 task_unlock(tsk);
492 put_files_struct(old);
493}
494EXPORT_SYMBOL(reset_files_struct);
495
496static inline void __exit_files(struct task_struct *tsk)
497{
498 struct files_struct * files = tsk->files;
499
500 if (files) {
501 task_lock(tsk);
502 tsk->files = NULL;
503 task_unlock(tsk);
504 put_files_struct(files);
505 }
506}
507
508void exit_files(struct task_struct *tsk)
509{
510 __exit_files(tsk);
511}
512
513static inline void __put_fs_struct(struct fs_struct *fs)
514{
515 /* No need to hold fs->lock if we are killing it */
516 if (atomic_dec_and_test(&fs->count)) {
517 dput(fs->root);
518 mntput(fs->rootmnt);
519 dput(fs->pwd);
520 mntput(fs->pwdmnt);
521 if (fs->altroot) {
522 dput(fs->altroot);
523 mntput(fs->altrootmnt);
524 }
525 kmem_cache_free(fs_cachep, fs);
526 }
527}
528
529void put_fs_struct(struct fs_struct *fs)
530{
531 __put_fs_struct(fs);
532}
533
534static inline void __exit_fs(struct task_struct *tsk)
535{
536 struct fs_struct * fs = tsk->fs;
537
538 if (fs) {
539 task_lock(tsk);
540 tsk->fs = NULL;
541 task_unlock(tsk);
542 __put_fs_struct(fs);
543 }
544}
545
546void exit_fs(struct task_struct *tsk)
547{
548 __exit_fs(tsk);
549}
550
551EXPORT_SYMBOL_GPL(exit_fs);
552
553/*
554 * Turn us into a lazy TLB process if we
555 * aren't already..
556 */
557static void exit_mm(struct task_struct * tsk)
558{
559 struct mm_struct *mm = tsk->mm;
560
561 mm_release(tsk, mm);
562 if (!mm)
563 return;
564 /*
565 * Serialize with any possible pending coredump.
566 * We must hold mmap_sem around checking core_waiters
567 * and clearing tsk->mm. The core-inducing thread
568 * will increment core_waiters for each thread in the
569 * group with ->mm != NULL.
570 */
571 down_read(&mm->mmap_sem);
572 if (mm->core_waiters) {
573 up_read(&mm->mmap_sem);
574 down_write(&mm->mmap_sem);
575 if (!--mm->core_waiters)
576 complete(mm->core_startup_done);
577 up_write(&mm->mmap_sem);
578
579 wait_for_completion(&mm->core_done);
580 down_read(&mm->mmap_sem);
581 }
582 atomic_inc(&mm->mm_count);
583 BUG_ON(mm != tsk->active_mm);
584 /* more a memory barrier than a real lock */
585 task_lock(tsk);
586 tsk->mm = NULL;
587 up_read(&mm->mmap_sem);
588 enter_lazy_tlb(mm, current);
589 /* We don't want this task to be frozen prematurely */
590 clear_freeze_flag(tsk);
591 task_unlock(tsk);
592 mmput(mm);
593}
594
595static inline void
596choose_new_parent(struct task_struct *p, struct task_struct *reaper)
597{
598 /*
599 * Make sure we're not reparenting to ourselves and that
600 * the parent is not a zombie.
601 */
602 BUG_ON(p == reaper || reaper->exit_state);
603 p->real_parent = reaper;
604}
605
606static void
607reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
608{
609 if (p->pdeath_signal)
610 /* We already hold the tasklist_lock here. */
611 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
612
613 /* Move the child from its dying parent to the new one. */
614 if (unlikely(traced)) {
615 /* Preserve ptrace links if someone else is tracing this child. */
616 list_del_init(&p->ptrace_list);
617 if (p->parent != p->real_parent)
618 list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
619 } else {
620 /* If this child is being traced, then we're the one tracing it
621 * anyway, so let go of it.
622 */
623 p->ptrace = 0;
624 remove_parent(p);
625 p->parent = p->real_parent;
626 add_parent(p);
627
628 if (p->state == TASK_TRACED) {
629 /*
630 * If it was at a trace stop, turn it into
631 * a normal stop since it's no longer being
632 * traced.
633 */
634 ptrace_untrace(p);
635 }
636 }
637
638 /* If this is a threaded reparent there is no need to
639 * notify anyone anything has happened.
640 */
641 if (p->real_parent->group_leader == father->group_leader)
642 return;
643
644 /* We don't want people slaying init. */
645 if (p->exit_signal != -1)
646 p->exit_signal = SIGCHLD;
647
648 /* If we'd notified the old parent about this child's death,
649 * also notify the new parent.
650 */
651 if (!traced && p->exit_state == EXIT_ZOMBIE &&
652 p->exit_signal != -1 && thread_group_empty(p))
653 do_notify_parent(p, p->exit_signal);
654
655 /*
656 * process group orphan check
657 * Case ii: Our child is in a different pgrp
658 * than we are, and it was the only connection
659 * outside, so the child pgrp is now orphaned.
660 */
661 if ((task_pgrp(p) != task_pgrp(father)) &&
662 (task_session(p) == task_session(father))) {
663 struct pid *pgrp = task_pgrp(p);
664
665 if (will_become_orphaned_pgrp(pgrp, NULL) &&
666 has_stopped_jobs(pgrp)) {
667 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
668 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
669 }
670 }
671}
672
673/*
674 * When we die, we re-parent all our children.
675 * Try to give them to another thread in our thread
676 * group, and if no such member exists, give it to
677 * the child reaper process (ie "init") in our pid
678 * space.
679 */
680static void
681forget_original_parent(struct task_struct *father, struct list_head *to_release)
682{
683 struct task_struct *p, *reaper = father;
684 struct list_head *_p, *_n;
685
686 do {
687 reaper = next_thread(reaper);
688 if (reaper == father) {
689 reaper = child_reaper(father);
690 break;
691 }
692 } while (reaper->exit_state);
693
694 /*
695 * There are only two places where our children can be:
696 *
697 * - in our child list
698 * - in our ptraced child list
699 *
700 * Search them and reparent children.
701 */
702 list_for_each_safe(_p, _n, &father->children) {
703 int ptrace;
704 p = list_entry(_p, struct task_struct, sibling);
705
706 ptrace = p->ptrace;
707
708 /* if father isn't the real parent, then ptrace must be enabled */
709 BUG_ON(father != p->real_parent && !ptrace);
710
711 if (father == p->real_parent) {
712 /* reparent with a reaper, real father it's us */
713 choose_new_parent(p, reaper);
714 reparent_thread(p, father, 0);
715 } else {
716 /* reparent ptraced task to its real parent */
717 __ptrace_unlink (p);
718 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
719 thread_group_empty(p))
720 do_notify_parent(p, p->exit_signal);
721 }
722
723 /*
724 * if the ptraced child is a zombie with exit_signal == -1
725 * we must collect it before we exit, or it will remain
726 * zombie forever since we prevented it from self-reap itself
727 * while it was being traced by us, to be able to see it in wait4.
728 */
729 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
730 list_add(&p->ptrace_list, to_release);
731 }
732 list_for_each_safe(_p, _n, &father->ptrace_children) {
733 p = list_entry(_p, struct task_struct, ptrace_list);
734 choose_new_parent(p, reaper);
735 reparent_thread(p, father, 1);
736 }
737}
738
739/*
740 * Send signals to all our closest relatives so that they know
741 * to properly mourn us..
742 */
743static void exit_notify(struct task_struct *tsk)
744{
745 int state;
746 struct task_struct *t;
747 struct list_head ptrace_dead, *_p, *_n;
748 struct pid *pgrp;
749
750 if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
751 && !thread_group_empty(tsk)) {
752 /*
753 * This occurs when there was a race between our exit
754 * syscall and a group signal choosing us as the one to
755 * wake up. It could be that we are the only thread
756 * alerted to check for pending signals, but another thread
757 * should be woken now to take the signal since we will not.
758 * Now we'll wake all the threads in the group just to make
759 * sure someone gets all the pending signals.
760 */
761 read_lock(&tasklist_lock);
762 spin_lock_irq(&tsk->sighand->siglock);
763 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
764 if (!signal_pending(t) && !(t->flags & PF_EXITING))
765 recalc_sigpending_and_wake(t);
766 spin_unlock_irq(&tsk->sighand->siglock);
767 read_unlock(&tasklist_lock);
768 }
769
770 write_lock_irq(&tasklist_lock);
771
772 /*
773 * This does two things:
774 *
775 * A. Make init inherit all the child processes
776 * B. Check to see if any process groups have become orphaned
777 * as a result of our exiting, and if they have any stopped
778 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
779 */
780
781 INIT_LIST_HEAD(&ptrace_dead);
782 forget_original_parent(tsk, &ptrace_dead);
783 BUG_ON(!list_empty(&tsk->children));
784 BUG_ON(!list_empty(&tsk->ptrace_children));
785
786 /*
787 * Check to see if any process groups have become orphaned
788 * as a result of our exiting, and if they have any stopped
789 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
790 *
791 * Case i: Our father is in a different pgrp than we are
792 * and we were the only connection outside, so our pgrp
793 * is about to become orphaned.
794 */
795
796 t = tsk->real_parent;
797
798 pgrp = task_pgrp(tsk);
799 if ((task_pgrp(t) != pgrp) &&
800 (task_session(t) == task_session(tsk)) &&
801 will_become_orphaned_pgrp(pgrp, tsk) &&
802 has_stopped_jobs(pgrp)) {
803 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
804 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
805 }
806
807 /* Let father know we died
808 *
809 * Thread signals are configurable, but you aren't going to use
810 * that to send signals to arbitary processes.
811 * That stops right now.
812 *
813 * If the parent exec id doesn't match the exec id we saved
814 * when we started then we know the parent has changed security
815 * domain.
816 *
817 * If our self_exec id doesn't match our parent_exec_id then
818 * we have changed execution domain as these two values started
819 * the same after a fork.
820 */
821 if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
822 ( tsk->parent_exec_id != t->self_exec_id ||
823 tsk->self_exec_id != tsk->parent_exec_id)
824 && !capable(CAP_KILL))
825 tsk->exit_signal = SIGCHLD;
826
827
828 /* If something other than our normal parent is ptracing us, then
829 * send it a SIGCHLD instead of honoring exit_signal. exit_signal
830 * only has special meaning to our real parent.
831 */
832 if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
833 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
834 do_notify_parent(tsk, signal);
835 } else if (tsk->ptrace) {
836 do_notify_parent(tsk, SIGCHLD);
837 }
838
839 state = EXIT_ZOMBIE;
840 if (tsk->exit_signal == -1 && likely(!tsk->ptrace))
841 state = EXIT_DEAD;
842 tsk->exit_state = state;
843
844 write_unlock_irq(&tasklist_lock);
845
846 list_for_each_safe(_p, _n, &ptrace_dead) {
847 list_del_init(_p);
848 t = list_entry(_p, struct task_struct, ptrace_list);
849 release_task(t);
850 }
851
852 /* If the process is dead, release it - nobody will wait for it */
853 if (state == EXIT_DEAD)
854 release_task(tsk);
855}
856
857#ifdef CONFIG_DEBUG_STACK_USAGE
858static void check_stack_usage(void)
859{
860 static DEFINE_SPINLOCK(low_water_lock);
861 static int lowest_to_date = THREAD_SIZE;
862 unsigned long *n = end_of_stack(current);
863 unsigned long free;
864
865 while (*n == 0)
866 n++;
867 free = (unsigned long)n - (unsigned long)end_of_stack(current);
868
869 if (free >= lowest_to_date)
870 return;
871
872 spin_lock(&low_water_lock);
873 if (free < lowest_to_date) {
874 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
875 "left\n",
876 current->comm, free);
877 lowest_to_date = free;
878 }
879 spin_unlock(&low_water_lock);
880}
881#else
882static inline void check_stack_usage(void) {}
883#endif
884
885fastcall NORET_TYPE void do_exit(long code)
886{
887 struct task_struct *tsk = current;
888 int group_dead;
889
890 profile_task_exit(tsk);
891
892 WARN_ON(atomic_read(&tsk->fs_excl));
893
894 if (unlikely(in_interrupt()))
895 panic("Aiee, killing interrupt handler!");
896 if (unlikely(!tsk->pid))
897 panic("Attempted to kill the idle task!");
898 if (unlikely(tsk == child_reaper(tsk))) {
899 if (tsk->nsproxy->pid_ns != &init_pid_ns)
900 tsk->nsproxy->pid_ns->child_reaper = init_pid_ns.child_reaper;
901 else
902 panic("Attempted to kill init!");
903 }
904
905
906 if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
907 current->ptrace_message = code;
908 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
909 }
910
911 /*
912 * We're taking recursive faults here in do_exit. Safest is to just
913 * leave this task alone and wait for reboot.
914 */
915 if (unlikely(tsk->flags & PF_EXITING)) {
916 printk(KERN_ALERT
917 "Fixing recursive fault but reboot is needed!\n");
918 /*
919 * We can do this unlocked here. The futex code uses
920 * this flag just to verify whether the pi state
921 * cleanup has been done or not. In the worst case it
922 * loops once more. We pretend that the cleanup was
923 * done as there is no way to return. Either the
924 * OWNER_DIED bit is set by now or we push the blocked
925 * task into the wait for ever nirwana as well.
926 */
927 tsk->flags |= PF_EXITPIDONE;
928 if (tsk->io_context)
929 exit_io_context();
930 set_current_state(TASK_UNINTERRUPTIBLE);
931 schedule();
932 }
933
934 /*
935 * tsk->flags are checked in the futex code to protect against
936 * an exiting task cleaning up the robust pi futexes.
937 */
938 spin_lock_irq(&tsk->pi_lock);
939 tsk->flags |= PF_EXITING;
940 spin_unlock_irq(&tsk->pi_lock);
941
942 if (unlikely(in_atomic()))
943 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
944 current->comm, current->pid,
945 preempt_count());
946
947 acct_update_integrals(tsk);
948 if (tsk->mm) {
949 update_hiwater_rss(tsk->mm);
950 update_hiwater_vm(tsk->mm);
951 }
952 group_dead = atomic_dec_and_test(&tsk->signal->live);
953 if (group_dead) {
954 hrtimer_cancel(&tsk->signal->real_timer);
955 exit_itimers(tsk->signal);
956 }
957 acct_collect(code, group_dead);
958 if (unlikely(tsk->robust_list))
959 exit_robust_list(tsk);
960#if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
961 if (unlikely(tsk->compat_robust_list))
962 compat_exit_robust_list(tsk);
963#endif
964 if (group_dead)
965 tty_audit_exit();
966 if (unlikely(tsk->audit_context))
967 audit_free(tsk);
968
969 tsk->exit_code = code;
970 taskstats_exit(tsk, group_dead);
971
972 exit_mm(tsk);
973
974 if (group_dead)
975 acct_process();
976 exit_sem(tsk);
977 __exit_files(tsk);
978 __exit_fs(tsk);
979 check_stack_usage();
980 exit_thread();
981 cpuset_exit(tsk);
982 exit_keys(tsk);
983
984 if (group_dead && tsk->signal->leader)
985 disassociate_ctty(1);
986
987 module_put(task_thread_info(tsk)->exec_domain->module);
988 if (tsk->binfmt)
989 module_put(tsk->binfmt->module);
990
991 proc_exit_connector(tsk);
992 exit_task_namespaces(tsk);
993 exit_notify(tsk);
994#ifdef CONFIG_NUMA
995 mpol_free(tsk->mempolicy);
996 tsk->mempolicy = NULL;
997#endif
998 /*
999 * This must happen late, after the PID is not
1000 * hashed anymore:
1001 */
1002 if (unlikely(!list_empty(&tsk->pi_state_list)))
1003 exit_pi_state_list(tsk);
1004 if (unlikely(current->pi_state_cache))
1005 kfree(current->pi_state_cache);
1006 /*
1007 * Make sure we are holding no locks:
1008 */
1009 debug_check_no_locks_held(tsk);
1010 /*
1011 * We can do this unlocked here. The futex code uses this flag
1012 * just to verify whether the pi state cleanup has been done
1013 * or not. In the worst case it loops once more.
1014 */
1015 tsk->flags |= PF_EXITPIDONE;
1016
1017 if (tsk->io_context)
1018 exit_io_context();
1019
1020 if (tsk->splice_pipe)
1021 __free_pipe_info(tsk->splice_pipe);
1022
1023 preempt_disable();
1024 /* causes final put_task_struct in finish_task_switch(). */
1025 tsk->state = TASK_DEAD;
1026
1027 schedule();
1028 BUG();
1029 /* Avoid "noreturn function does return". */
1030 for (;;)
1031 cpu_relax(); /* For when BUG is null */
1032}
1033
1034EXPORT_SYMBOL_GPL(do_exit);
1035
1036NORET_TYPE void complete_and_exit(struct completion *comp, long code)
1037{
1038 if (comp)
1039 complete(comp);
1040
1041 do_exit(code);
1042}
1043
1044EXPORT_SYMBOL(complete_and_exit);
1045
1046asmlinkage long sys_exit(int error_code)
1047{
1048 do_exit((error_code&0xff)<<8);
1049}
1050
1051/*
1052 * Take down every thread in the group. This is called by fatal signals
1053 * as well as by sys_exit_group (below).
1054 */
1055NORET_TYPE void
1056do_group_exit(int exit_code)
1057{
1058 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1059
1060 if (current->signal->flags & SIGNAL_GROUP_EXIT)
1061 exit_code = current->signal->group_exit_code;
1062 else if (!thread_group_empty(current)) {
1063 struct signal_struct *const sig = current->signal;
1064 struct sighand_struct *const sighand = current->sighand;
1065 spin_lock_irq(&sighand->siglock);
1066 if (sig->flags & SIGNAL_GROUP_EXIT)
1067 /* Another thread got here before we took the lock. */
1068 exit_code = sig->group_exit_code;
1069 else {
1070 sig->group_exit_code = exit_code;
1071 zap_other_threads(current);
1072 }
1073 spin_unlock_irq(&sighand->siglock);
1074 }
1075
1076 do_exit(exit_code);
1077 /* NOTREACHED */
1078}
1079
1080/*
1081 * this kills every thread in the thread group. Note that any externally
1082 * wait4()-ing process will get the correct exit code - even if this
1083 * thread is not the thread group leader.
1084 */
1085asmlinkage void sys_exit_group(int error_code)
1086{
1087 do_group_exit((error_code & 0xff) << 8);
1088}
1089
1090static int eligible_child(pid_t pid, int options, struct task_struct *p)
1091{
1092 int err;
1093
1094 if (pid > 0) {
1095 if (p->pid != pid)
1096 return 0;
1097 } else if (!pid) {
1098 if (process_group(p) != process_group(current))
1099 return 0;
1100 } else if (pid != -1) {
1101 if (process_group(p) != -pid)
1102 return 0;
1103 }
1104
1105 /*
1106 * Do not consider detached threads that are
1107 * not ptraced:
1108 */
1109 if (p->exit_signal == -1 && !p->ptrace)
1110 return 0;
1111
1112 /* Wait for all children (clone and not) if __WALL is set;
1113 * otherwise, wait for clone children *only* if __WCLONE is
1114 * set; otherwise, wait for non-clone children *only*. (Note:
1115 * A "clone" child here is one that reports to its parent
1116 * using a signal other than SIGCHLD.) */
1117 if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1118 && !(options & __WALL))
1119 return 0;
1120 /*
1121 * Do not consider thread group leaders that are
1122 * in a non-empty thread group:
1123 */
1124 if (delay_group_leader(p))
1125 return 2;
1126
1127 err = security_task_wait(p);
1128 if (err)
1129 return err;
1130
1131 return 1;
1132}
1133
1134static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1135 int why, int status,
1136 struct siginfo __user *infop,
1137 struct rusage __user *rusagep)
1138{
1139 int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1140
1141 put_task_struct(p);
1142 if (!retval)
1143 retval = put_user(SIGCHLD, &infop->si_signo);
1144 if (!retval)
1145 retval = put_user(0, &infop->si_errno);
1146 if (!retval)
1147 retval = put_user((short)why, &infop->si_code);
1148 if (!retval)
1149 retval = put_user(pid, &infop->si_pid);
1150 if (!retval)
1151 retval = put_user(uid, &infop->si_uid);
1152 if (!retval)
1153 retval = put_user(status, &infop->si_status);
1154 if (!retval)
1155 retval = pid;
1156 return retval;
1157}
1158
1159/*
1160 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1161 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1162 * the lock and this task is uninteresting. If we return nonzero, we have
1163 * released the lock and the system call should return.
1164 */
1165static int wait_task_zombie(struct task_struct *p, int noreap,
1166 struct siginfo __user *infop,
1167 int __user *stat_addr, struct rusage __user *ru)
1168{
1169 unsigned long state;
1170 int retval;
1171 int status;
1172
1173 if (unlikely(noreap)) {
1174 pid_t pid = p->pid;
1175 uid_t uid = p->uid;
1176 int exit_code = p->exit_code;
1177 int why, status;
1178
1179 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1180 return 0;
1181 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1182 return 0;
1183 get_task_struct(p);
1184 read_unlock(&tasklist_lock);
1185 if ((exit_code & 0x7f) == 0) {
1186 why = CLD_EXITED;
1187 status = exit_code >> 8;
1188 } else {
1189 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1190 status = exit_code & 0x7f;
1191 }
1192 return wait_noreap_copyout(p, pid, uid, why,
1193 status, infop, ru);
1194 }
1195
1196 /*
1197 * Try to move the task's state to DEAD
1198 * only one thread is allowed to do this:
1199 */
1200 state = xchg(&p->exit_state, EXIT_DEAD);
1201 if (state != EXIT_ZOMBIE) {
1202 BUG_ON(state != EXIT_DEAD);
1203 return 0;
1204 }
1205 if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1206 /*
1207 * This can only happen in a race with a ptraced thread
1208 * dying on another processor.
1209 */
1210 return 0;
1211 }
1212
1213 if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1214 struct signal_struct *psig;
1215 struct signal_struct *sig;
1216
1217 /*
1218 * The resource counters for the group leader are in its
1219 * own task_struct. Those for dead threads in the group
1220 * are in its signal_struct, as are those for the child
1221 * processes it has previously reaped. All these
1222 * accumulate in the parent's signal_struct c* fields.
1223 *
1224 * We don't bother to take a lock here to protect these
1225 * p->signal fields, because they are only touched by
1226 * __exit_signal, which runs with tasklist_lock
1227 * write-locked anyway, and so is excluded here. We do
1228 * need to protect the access to p->parent->signal fields,
1229 * as other threads in the parent group can be right
1230 * here reaping other children at the same time.
1231 */
1232 spin_lock_irq(&p->parent->sighand->siglock);
1233 psig = p->parent->signal;
1234 sig = p->signal;
1235 psig->cutime =
1236 cputime_add(psig->cutime,
1237 cputime_add(p->utime,
1238 cputime_add(sig->utime,
1239 sig->cutime)));
1240 psig->cstime =
1241 cputime_add(psig->cstime,
1242 cputime_add(p->stime,
1243 cputime_add(sig->stime,
1244 sig->cstime)));
1245 psig->cmin_flt +=
1246 p->min_flt + sig->min_flt + sig->cmin_flt;
1247 psig->cmaj_flt +=
1248 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1249 psig->cnvcsw +=
1250 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1251 psig->cnivcsw +=
1252 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1253 psig->cinblock +=
1254 task_io_get_inblock(p) +
1255 sig->inblock + sig->cinblock;
1256 psig->coublock +=
1257 task_io_get_oublock(p) +
1258 sig->oublock + sig->coublock;
1259 spin_unlock_irq(&p->parent->sighand->siglock);
1260 }
1261
1262 /*
1263 * Now we are sure this task is interesting, and no other
1264 * thread can reap it because we set its state to EXIT_DEAD.
1265 */
1266 read_unlock(&tasklist_lock);
1267
1268 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1269 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1270 ? p->signal->group_exit_code : p->exit_code;
1271 if (!retval && stat_addr)
1272 retval = put_user(status, stat_addr);
1273 if (!retval && infop)
1274 retval = put_user(SIGCHLD, &infop->si_signo);
1275 if (!retval && infop)
1276 retval = put_user(0, &infop->si_errno);
1277 if (!retval && infop) {
1278 int why;
1279
1280 if ((status & 0x7f) == 0) {
1281 why = CLD_EXITED;
1282 status >>= 8;
1283 } else {
1284 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1285 status &= 0x7f;
1286 }
1287 retval = put_user((short)why, &infop->si_code);
1288 if (!retval)
1289 retval = put_user(status, &infop->si_status);
1290 }
1291 if (!retval && infop)
1292 retval = put_user(p->pid, &infop->si_pid);
1293 if (!retval && infop)
1294 retval = put_user(p->uid, &infop->si_uid);
1295 if (retval) {
1296 // TODO: is this safe?
1297 p->exit_state = EXIT_ZOMBIE;
1298 return retval;
1299 }
1300 retval = p->pid;
1301 if (p->real_parent != p->parent) {
1302 write_lock_irq(&tasklist_lock);
1303 /* Double-check with lock held. */
1304 if (p->real_parent != p->parent) {
1305 __ptrace_unlink(p);
1306 // TODO: is this safe?
1307 p->exit_state = EXIT_ZOMBIE;
1308 /*
1309 * If this is not a detached task, notify the parent.
1310 * If it's still not detached after that, don't release
1311 * it now.
1312 */
1313 if (p->exit_signal != -1) {
1314 do_notify_parent(p, p->exit_signal);
1315 if (p->exit_signal != -1)
1316 p = NULL;
1317 }
1318 }
1319 write_unlock_irq(&tasklist_lock);
1320 }
1321 if (p != NULL)
1322 release_task(p);
1323 BUG_ON(!retval);
1324 return retval;
1325}
1326
1327/*
1328 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1329 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1330 * the lock and this task is uninteresting. If we return nonzero, we have
1331 * released the lock and the system call should return.
1332 */
1333static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1334 int noreap, struct siginfo __user *infop,
1335 int __user *stat_addr, struct rusage __user *ru)
1336{
1337 int retval, exit_code;
1338
1339 if (!p->exit_code)
1340 return 0;
1341 if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1342 p->signal && p->signal->group_stop_count > 0)
1343 /*
1344 * A group stop is in progress and this is the group leader.
1345 * We won't report until all threads have stopped.
1346 */
1347 return 0;
1348
1349 /*
1350 * Now we are pretty sure this task is interesting.
1351 * Make sure it doesn't get reaped out from under us while we
1352 * give up the lock and then examine it below. We don't want to
1353 * keep holding onto the tasklist_lock while we call getrusage and
1354 * possibly take page faults for user memory.
1355 */
1356 get_task_struct(p);
1357 read_unlock(&tasklist_lock);
1358
1359 if (unlikely(noreap)) {
1360 pid_t pid = p->pid;
1361 uid_t uid = p->uid;
1362 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1363
1364 exit_code = p->exit_code;
1365 if (unlikely(!exit_code) ||
1366 unlikely(p->state & TASK_TRACED))
1367 goto bail_ref;
1368 return wait_noreap_copyout(p, pid, uid,
1369 why, (exit_code << 8) | 0x7f,
1370 infop, ru);
1371 }
1372
1373 write_lock_irq(&tasklist_lock);
1374
1375 /*
1376 * This uses xchg to be atomic with the thread resuming and setting
1377 * it. It must also be done with the write lock held to prevent a
1378 * race with the EXIT_ZOMBIE case.
1379 */
1380 exit_code = xchg(&p->exit_code, 0);
1381 if (unlikely(p->exit_state)) {
1382 /*
1383 * The task resumed and then died. Let the next iteration
1384 * catch it in EXIT_ZOMBIE. Note that exit_code might
1385 * already be zero here if it resumed and did _exit(0).
1386 * The task itself is dead and won't touch exit_code again;
1387 * other processors in this function are locked out.
1388 */
1389 p->exit_code = exit_code;
1390 exit_code = 0;
1391 }
1392 if (unlikely(exit_code == 0)) {
1393 /*
1394 * Another thread in this function got to it first, or it
1395 * resumed, or it resumed and then died.
1396 */
1397 write_unlock_irq(&tasklist_lock);
1398bail_ref:
1399 put_task_struct(p);
1400 /*
1401 * We are returning to the wait loop without having successfully
1402 * removed the process and having released the lock. We cannot
1403 * continue, since the "p" task pointer is potentially stale.
1404 *
1405 * Return -EAGAIN, and do_wait() will restart the loop from the
1406 * beginning. Do _not_ re-acquire the lock.
1407 */
1408 return -EAGAIN;
1409 }
1410
1411 /* move to end of parent's list to avoid starvation */
1412 remove_parent(p);
1413 add_parent(p);
1414
1415 write_unlock_irq(&tasklist_lock);
1416
1417 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1418 if (!retval && stat_addr)
1419 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1420 if (!retval && infop)
1421 retval = put_user(SIGCHLD, &infop->si_signo);
1422 if (!retval && infop)
1423 retval = put_user(0, &infop->si_errno);
1424 if (!retval && infop)
1425 retval = put_user((short)((p->ptrace & PT_PTRACED)
1426 ? CLD_TRAPPED : CLD_STOPPED),
1427 &infop->si_code);
1428 if (!retval && infop)
1429 retval = put_user(exit_code, &infop->si_status);
1430 if (!retval && infop)
1431 retval = put_user(p->pid, &infop->si_pid);
1432 if (!retval && infop)
1433 retval = put_user(p->uid, &infop->si_uid);
1434 if (!retval)
1435 retval = p->pid;
1436 put_task_struct(p);
1437
1438 BUG_ON(!retval);
1439 return retval;
1440}
1441
1442/*
1443 * Handle do_wait work for one task in a live, non-stopped state.
1444 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1445 * the lock and this task is uninteresting. If we return nonzero, we have
1446 * released the lock and the system call should return.
1447 */
1448static int wait_task_continued(struct task_struct *p, int noreap,
1449 struct siginfo __user *infop,
1450 int __user *stat_addr, struct rusage __user *ru)
1451{
1452 int retval;
1453 pid_t pid;
1454 uid_t uid;
1455
1456 if (unlikely(!p->signal))
1457 return 0;
1458
1459 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1460 return 0;
1461
1462 spin_lock_irq(&p->sighand->siglock);
1463 /* Re-check with the lock held. */
1464 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1465 spin_unlock_irq(&p->sighand->siglock);
1466 return 0;
1467 }
1468 if (!noreap)
1469 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1470 spin_unlock_irq(&p->sighand->siglock);
1471
1472 pid = p->pid;
1473 uid = p->uid;
1474 get_task_struct(p);
1475 read_unlock(&tasklist_lock);
1476
1477 if (!infop) {
1478 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1479 put_task_struct(p);
1480 if (!retval && stat_addr)
1481 retval = put_user(0xffff, stat_addr);
1482 if (!retval)
1483 retval = p->pid;
1484 } else {
1485 retval = wait_noreap_copyout(p, pid, uid,
1486 CLD_CONTINUED, SIGCONT,
1487 infop, ru);
1488 BUG_ON(retval == 0);
1489 }
1490
1491 return retval;
1492}
1493
1494
1495static inline int my_ptrace_child(struct task_struct *p)
1496{
1497 if (!(p->ptrace & PT_PTRACED))
1498 return 0;
1499 if (!(p->ptrace & PT_ATTACHED))
1500 return 1;
1501 /*
1502 * This child was PTRACE_ATTACH'd. We should be seeing it only if
1503 * we are the attacher. If we are the real parent, this is a race
1504 * inside ptrace_attach. It is waiting for the tasklist_lock,
1505 * which we have to switch the parent links, but has already set
1506 * the flags in p->ptrace.
1507 */
1508 return (p->parent != p->real_parent);
1509}
1510
1511static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1512 int __user *stat_addr, struct rusage __user *ru)
1513{
1514 DECLARE_WAITQUEUE(wait, current);
1515 struct task_struct *tsk;
1516 int flag, retval;
1517 int allowed, denied;
1518
1519 add_wait_queue(&current->signal->wait_chldexit,&wait);
1520repeat:
1521 /*
1522 * We will set this flag if we see any child that might later
1523 * match our criteria, even if we are not able to reap it yet.
1524 */
1525 flag = 0;
1526 allowed = denied = 0;
1527 current->state = TASK_INTERRUPTIBLE;
1528 read_lock(&tasklist_lock);
1529 tsk = current;
1530 do {
1531 struct task_struct *p;
1532 struct list_head *_p;
1533 int ret;
1534
1535 list_for_each(_p,&tsk->children) {
1536 p = list_entry(_p, struct task_struct, sibling);
1537
1538 ret = eligible_child(pid, options, p);
1539 if (!ret)
1540 continue;
1541
1542 if (unlikely(ret < 0)) {
1543 denied = ret;
1544 continue;
1545 }
1546 allowed = 1;
1547
1548 switch (p->state) {
1549 case TASK_TRACED:
1550 /*
1551 * When we hit the race with PTRACE_ATTACH,
1552 * we will not report this child. But the
1553 * race means it has not yet been moved to
1554 * our ptrace_children list, so we need to
1555 * set the flag here to avoid a spurious ECHILD
1556 * when the race happens with the only child.
1557 */
1558 flag = 1;
1559 if (!my_ptrace_child(p))
1560 continue;
1561 /*FALLTHROUGH*/
1562 case TASK_STOPPED:
1563 /*
1564 * It's stopped now, so it might later
1565 * continue, exit, or stop again.
1566 */
1567 flag = 1;
1568 if (!(options & WUNTRACED) &&
1569 !my_ptrace_child(p))
1570 continue;
1571 retval = wait_task_stopped(p, ret == 2,
1572 (options & WNOWAIT),
1573 infop,
1574 stat_addr, ru);
1575 if (retval == -EAGAIN)
1576 goto repeat;
1577 if (retval != 0) /* He released the lock. */
1578 goto end;
1579 break;
1580 default:
1581 // case EXIT_DEAD:
1582 if (p->exit_state == EXIT_DEAD)
1583 continue;
1584 // case EXIT_ZOMBIE:
1585 if (p->exit_state == EXIT_ZOMBIE) {
1586 /*
1587 * Eligible but we cannot release
1588 * it yet:
1589 */
1590 if (ret == 2)
1591 goto check_continued;
1592 if (!likely(options & WEXITED))
1593 continue;
1594 retval = wait_task_zombie(
1595 p, (options & WNOWAIT),
1596 infop, stat_addr, ru);
1597 /* He released the lock. */
1598 if (retval != 0)
1599 goto end;
1600 break;
1601 }
1602check_continued:
1603 /*
1604 * It's running now, so it might later
1605 * exit, stop, or stop and then continue.
1606 */
1607 flag = 1;
1608 if (!unlikely(options & WCONTINUED))
1609 continue;
1610 retval = wait_task_continued(
1611 p, (options & WNOWAIT),
1612 infop, stat_addr, ru);
1613 if (retval != 0) /* He released the lock. */
1614 goto end;
1615 break;
1616 }
1617 }
1618 if (!flag) {
1619 list_for_each(_p, &tsk->ptrace_children) {
1620 p = list_entry(_p, struct task_struct,
1621 ptrace_list);
1622 if (!eligible_child(pid, options, p))
1623 continue;
1624 flag = 1;
1625 break;
1626 }
1627 }
1628 if (options & __WNOTHREAD)
1629 break;
1630 tsk = next_thread(tsk);
1631 BUG_ON(tsk->signal != current->signal);
1632 } while (tsk != current);
1633
1634 read_unlock(&tasklist_lock);
1635 if (flag) {
1636 retval = 0;
1637 if (options & WNOHANG)
1638 goto end;
1639 retval = -ERESTARTSYS;
1640 if (signal_pending(current))
1641 goto end;
1642 schedule();
1643 goto repeat;
1644 }
1645 retval = -ECHILD;
1646 if (unlikely(denied) && !allowed)
1647 retval = denied;
1648end:
1649 current->state = TASK_RUNNING;
1650 remove_wait_queue(&current->signal->wait_chldexit,&wait);
1651 if (infop) {
1652 if (retval > 0)
1653 retval = 0;
1654 else {
1655 /*
1656 * For a WNOHANG return, clear out all the fields
1657 * we would set so the user can easily tell the
1658 * difference.
1659 */
1660 if (!retval)
1661 retval = put_user(0, &infop->si_signo);
1662 if (!retval)
1663 retval = put_user(0, &infop->si_errno);
1664 if (!retval)
1665 retval = put_user(0, &infop->si_code);
1666 if (!retval)
1667 retval = put_user(0, &infop->si_pid);
1668 if (!retval)
1669 retval = put_user(0, &infop->si_uid);
1670 if (!retval)
1671 retval = put_user(0, &infop->si_status);
1672 }
1673 }
1674 return retval;
1675}
1676
1677asmlinkage long sys_waitid(int which, pid_t pid,
1678 struct siginfo __user *infop, int options,
1679 struct rusage __user *ru)
1680{
1681 long ret;
1682
1683 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1684 return -EINVAL;
1685 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1686 return -EINVAL;
1687
1688 switch (which) {
1689 case P_ALL:
1690 pid = -1;
1691 break;
1692 case P_PID:
1693 if (pid <= 0)
1694 return -EINVAL;
1695 break;
1696 case P_PGID:
1697 if (pid <= 0)
1698 return -EINVAL;
1699 pid = -pid;
1700 break;
1701 default:
1702 return -EINVAL;
1703 }
1704
1705 ret = do_wait(pid, options, infop, NULL, ru);
1706
1707 /* avoid REGPARM breakage on x86: */
1708 prevent_tail_call(ret);
1709 return ret;
1710}
1711
1712asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1713 int options, struct rusage __user *ru)
1714{
1715 long ret;
1716
1717 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1718 __WNOTHREAD|__WCLONE|__WALL))
1719 return -EINVAL;
1720 ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1721
1722 /* avoid REGPARM breakage on x86: */
1723 prevent_tail_call(ret);
1724 return ret;
1725}
1726
1727#ifdef __ARCH_WANT_SYS_WAITPID
1728
1729/*
1730 * sys_waitpid() remains for compatibility. waitpid() should be
1731 * implemented by calling sys_wait4() from libc.a.
1732 */
1733asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1734{
1735 return sys_wait4(pid, stat_addr, options, NULL);
1736}
1737
1738#endif