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