projects/linux·blob v2.6.20 · refs

1662 lines · 41.7 KiB

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