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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 int zap_leader;
138 task_t *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, task_t *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 choose_new_parent(task_t *p, task_t *reaper)
586 {
587 /*
588 * Make sure we're not reparenting to ourselves and that
589 * the parent is not a zombie.
590 */
591 BUG_ON(p == reaper || reaper->exit_state);
592 p->real_parent = reaper;
593 }
594
595 static void reparent_thread(task_t *p, task_t *father, int traced)
596 {
597 /* We don't want people slaying init. */
598 if (p->exit_signal != -1)
599 p->exit_signal = SIGCHLD;
600
601 if (p->pdeath_signal)
602 /* We already hold the tasklist_lock here. */
603 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
604
605 /* Move the child from its dying parent to the new one. */
606 if (unlikely(traced)) {
607 /* Preserve ptrace links if someone else is tracing this child. */
608 list_del_init(&p->ptrace_list);
609 if (p->parent != p->real_parent)
610 list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
611 } else {
612 /* If this child is being traced, then we're the one tracing it
613 * anyway, so let go of it.
614 */
615 p->ptrace = 0;
616 remove_parent(p);
617 p->parent = p->real_parent;
618 add_parent(p);
619
620 /* If we'd notified the old parent about this child's death,
621 * also notify the new parent.
622 */
623 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
624 thread_group_empty(p))
625 do_notify_parent(p, p->exit_signal);
626 else if (p->state == TASK_TRACED) {
627 /*
628 * If it was at a trace stop, turn it into
629 * a normal stop since it's no longer being
630 * traced.
631 */
632 ptrace_untrace(p);
633 }
634 }
635
636 /*
637 * process group orphan check
638 * Case ii: Our child is in a different pgrp
639 * than we are, and it was the only connection
640 * outside, so the child pgrp is now orphaned.
641 */
642 if ((process_group(p) != process_group(father)) &&
643 (p->signal->session == father->signal->session)) {
644 int pgrp = process_group(p);
645
646 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
647 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
648 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
649 }
650 }
651 }
652
653 /*
654 * When we die, we re-parent all our children.
655 * Try to give them to another thread in our thread
656 * group, and if no such member exists, give it to
657 * the global child reaper process (ie "init")
658 */
659 static void forget_original_parent(struct task_struct * father,
660 struct list_head *to_release)
661 {
662 struct task_struct *p, *reaper = father;
663 struct list_head *_p, *_n;
664
665 do {
666 reaper = next_thread(reaper);
667 if (reaper == father) {
668 reaper = child_reaper;
669 break;
670 }
671 } while (reaper->exit_state);
672
673 /*
674 * There are only two places where our children can be:
675 *
676 * - in our child list
677 * - in our ptraced child list
678 *
679 * Search them and reparent children.
680 */
681 list_for_each_safe(_p, _n, &father->children) {
682 int ptrace;
683 p = list_entry(_p,struct task_struct,sibling);
684
685 ptrace = p->ptrace;
686
687 /* if father isn't the real parent, then ptrace must be enabled */
688 BUG_ON(father != p->real_parent && !ptrace);
689
690 if (father == p->real_parent) {
691 /* reparent with a reaper, real father it's us */
692 choose_new_parent(p, reaper);
693 reparent_thread(p, father, 0);
694 } else {
695 /* reparent ptraced task to its real parent */
696 __ptrace_unlink (p);
697 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
698 thread_group_empty(p))
699 do_notify_parent(p, p->exit_signal);
700 }
701
702 /*
703 * if the ptraced child is a zombie with exit_signal == -1
704 * we must collect it before we exit, or it will remain
705 * zombie forever since we prevented it from self-reap itself
706 * while it was being traced by us, to be able to see it in wait4.
707 */
708 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
709 list_add(&p->ptrace_list, to_release);
710 }
711 list_for_each_safe(_p, _n, &father->ptrace_children) {
712 p = list_entry(_p,struct task_struct,ptrace_list);
713 choose_new_parent(p, reaper);
714 reparent_thread(p, father, 1);
715 }
716 }
717
718 /*
719 * Send signals to all our closest relatives so that they know
720 * to properly mourn us..
721 */
722 static void exit_notify(struct task_struct *tsk)
723 {
724 int state;
725 struct task_struct *t;
726 struct list_head ptrace_dead, *_p, *_n;
727
728 if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
729 && !thread_group_empty(tsk)) {
730 /*
731 * This occurs when there was a race between our exit
732 * syscall and a group signal choosing us as the one to
733 * wake up. It could be that we are the only thread
734 * alerted to check for pending signals, but another thread
735 * should be woken now to take the signal since we will not.
736 * Now we'll wake all the threads in the group just to make
737 * sure someone gets all the pending signals.
738 */
739 read_lock(&tasklist_lock);
740 spin_lock_irq(&tsk->sighand->siglock);
741 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
742 if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
743 recalc_sigpending_tsk(t);
744 if (signal_pending(t))
745 signal_wake_up(t, 0);
746 }
747 spin_unlock_irq(&tsk->sighand->siglock);
748 read_unlock(&tasklist_lock);
749 }
750
751 write_lock_irq(&tasklist_lock);
752
753 /*
754 * This does two things:
755 *
756 * A. Make init inherit all the child processes
757 * B. Check to see if any process groups have become orphaned
758 * as a result of our exiting, and if they have any stopped
759 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
760 */
761
762 INIT_LIST_HEAD(&ptrace_dead);
763 forget_original_parent(tsk, &ptrace_dead);
764 BUG_ON(!list_empty(&tsk->children));
765 BUG_ON(!list_empty(&tsk->ptrace_children));
766
767 /*
768 * Check to see if any process groups have become orphaned
769 * as a result of our exiting, and if they have any stopped
770 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
771 *
772 * Case i: Our father is in a different pgrp than we are
773 * and we were the only connection outside, so our pgrp
774 * is about to become orphaned.
775 */
776
777 t = tsk->real_parent;
778
779 if ((process_group(t) != process_group(tsk)) &&
780 (t->signal->session == tsk->signal->session) &&
781 will_become_orphaned_pgrp(process_group(tsk), tsk) &&
782 has_stopped_jobs(process_group(tsk))) {
783 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
784 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
785 }
786
787 /* Let father know we died
788 *
789 * Thread signals are configurable, but you aren't going to use
790 * that to send signals to arbitary processes.
791 * That stops right now.
792 *
793 * If the parent exec id doesn't match the exec id we saved
794 * when we started then we know the parent has changed security
795 * domain.
796 *
797 * If our self_exec id doesn't match our parent_exec_id then
798 * we have changed execution domain as these two values started
799 * the same after a fork.
800 *
801 */
802
803 if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
804 ( tsk->parent_exec_id != t->self_exec_id ||
805 tsk->self_exec_id != tsk->parent_exec_id)
806 && !capable(CAP_KILL))
807 tsk->exit_signal = SIGCHLD;
808
809
810 /* If something other than our normal parent is ptracing us, then
811 * send it a SIGCHLD instead of honoring exit_signal. exit_signal
812 * only has special meaning to our real parent.
813 */
814 if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
815 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
816 do_notify_parent(tsk, signal);
817 } else if (tsk->ptrace) {
818 do_notify_parent(tsk, SIGCHLD);
819 }
820
821 state = EXIT_ZOMBIE;
822 if (tsk->exit_signal == -1 &&
823 (likely(tsk->ptrace == 0) ||
824 unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
825 state = EXIT_DEAD;
826 tsk->exit_state = state;
827
828 write_unlock_irq(&tasklist_lock);
829
830 list_for_each_safe(_p, _n, &ptrace_dead) {
831 list_del_init(_p);
832 t = list_entry(_p,struct task_struct,ptrace_list);
833 release_task(t);
834 }
835
836 /* If the process is dead, release it - nobody will wait for it */
837 if (state == EXIT_DEAD)
838 release_task(tsk);
839 }
840
841 fastcall NORET_TYPE void do_exit(long code)
842 {
843 struct task_struct *tsk = current;
844 int group_dead;
845
846 profile_task_exit(tsk);
847
848 WARN_ON(atomic_read(&tsk->fs_excl));
849
850 if (unlikely(in_interrupt()))
851 panic("Aiee, killing interrupt handler!");
852 if (unlikely(!tsk->pid))
853 panic("Attempted to kill the idle task!");
854 if (unlikely(tsk == child_reaper))
855 panic("Attempted to kill init!");
856
857 if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
858 current->ptrace_message = code;
859 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
860 }
861
862 /*
863 * We're taking recursive faults here in do_exit. Safest is to just
864 * leave this task alone and wait for reboot.
865 */
866 if (unlikely(tsk->flags & PF_EXITING)) {
867 printk(KERN_ALERT
868 "Fixing recursive fault but reboot is needed!\n");
869 if (tsk->io_context)
870 exit_io_context();
871 set_current_state(TASK_UNINTERRUPTIBLE);
872 schedule();
873 }
874
875 tsk->flags |= PF_EXITING;
876
877 if (unlikely(in_atomic()))
878 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
879 current->comm, current->pid,
880 preempt_count());
881
882 acct_update_integrals(tsk);
883 if (tsk->mm) {
884 update_hiwater_rss(tsk->mm);
885 update_hiwater_vm(tsk->mm);
886 }
887 group_dead = atomic_dec_and_test(&tsk->signal->live);
888 if (group_dead) {
889 hrtimer_cancel(&tsk->signal->real_timer);
890 exit_itimers(tsk->signal);
891 }
892 acct_collect(code, group_dead);
893 if (unlikely(tsk->robust_list))
894 exit_robust_list(tsk);
895 #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
896 if (unlikely(tsk->compat_robust_list))
897 compat_exit_robust_list(tsk);
898 #endif
899 if (unlikely(tsk->audit_context))
900 audit_free(tsk);
901 exit_mm(tsk);
902
903 if (group_dead)
904 acct_process();
905 exit_sem(tsk);
906 __exit_files(tsk);
907 __exit_fs(tsk);
908 exit_namespace(tsk);
909 exit_thread();
910 cpuset_exit(tsk);
911 exit_keys(tsk);
912
913 if (group_dead && tsk->signal->leader)
914 disassociate_ctty(1);
915
916 module_put(task_thread_info(tsk)->exec_domain->module);
917 if (tsk->binfmt)
918 module_put(tsk->binfmt->module);
919
920 tsk->exit_code = code;
921 proc_exit_connector(tsk);
922 exit_notify(tsk);
923 #ifdef CONFIG_NUMA
924 mpol_free(tsk->mempolicy);
925 tsk->mempolicy = NULL;
926 #endif
927 /*
928 * This must happen late, after the PID is not
929 * hashed anymore:
930 */
931 if (unlikely(!list_empty(&tsk->pi_state_list)))
932 exit_pi_state_list(tsk);
933 if (unlikely(current->pi_state_cache))
934 kfree(current->pi_state_cache);
935 /*
936 * If DEBUG_MUTEXES is on, make sure we are holding no locks:
937 */
938 mutex_debug_check_no_locks_held(tsk);
939 rt_mutex_debug_check_no_locks_held(tsk);
940
941 if (tsk->io_context)
942 exit_io_context();
943
944 if (tsk->splice_pipe)
945 __free_pipe_info(tsk->splice_pipe);
946
947 /* PF_DEAD causes final put_task_struct after we schedule. */
948 preempt_disable();
949 BUG_ON(tsk->flags & PF_DEAD);
950 tsk->flags |= PF_DEAD;
951
952 schedule();
953 BUG();
954 /* Avoid "noreturn function does return". */
955 for (;;) ;
956 }
957
958 EXPORT_SYMBOL_GPL(do_exit);
959
960 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
961 {
962 if (comp)
963 complete(comp);
964
965 do_exit(code);
966 }
967
968 EXPORT_SYMBOL(complete_and_exit);
969
970 asmlinkage long sys_exit(int error_code)
971 {
972 do_exit((error_code&0xff)<<8);
973 }
974
975 /*
976 * Take down every thread in the group. This is called by fatal signals
977 * as well as by sys_exit_group (below).
978 */
979 NORET_TYPE void
980 do_group_exit(int exit_code)
981 {
982 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
983
984 if (current->signal->flags & SIGNAL_GROUP_EXIT)
985 exit_code = current->signal->group_exit_code;
986 else if (!thread_group_empty(current)) {
987 struct signal_struct *const sig = current->signal;
988 struct sighand_struct *const sighand = current->sighand;
989 spin_lock_irq(&sighand->siglock);
990 if (sig->flags & SIGNAL_GROUP_EXIT)
991 /* Another thread got here before we took the lock. */
992 exit_code = sig->group_exit_code;
993 else {
994 sig->group_exit_code = exit_code;
995 zap_other_threads(current);
996 }
997 spin_unlock_irq(&sighand->siglock);
998 }
999
1000 do_exit(exit_code);
1001 /* NOTREACHED */
1002 }
1003
1004 /*
1005 * this kills every thread in the thread group. Note that any externally
1006 * wait4()-ing process will get the correct exit code - even if this
1007 * thread is not the thread group leader.
1008 */
1009 asmlinkage void sys_exit_group(int error_code)
1010 {
1011 do_group_exit((error_code & 0xff) << 8);
1012 }
1013
1014 static int eligible_child(pid_t pid, int options, task_t *p)
1015 {
1016 if (pid > 0) {
1017 if (p->pid != pid)
1018 return 0;
1019 } else if (!pid) {
1020 if (process_group(p) != process_group(current))
1021 return 0;
1022 } else if (pid != -1) {
1023 if (process_group(p) != -pid)
1024 return 0;
1025 }
1026
1027 /*
1028 * Do not consider detached threads that are
1029 * not ptraced:
1030 */
1031 if (p->exit_signal == -1 && !p->ptrace)
1032 return 0;
1033
1034 /* Wait for all children (clone and not) if __WALL is set;
1035 * otherwise, wait for clone children *only* if __WCLONE is
1036 * set; otherwise, wait for non-clone children *only*. (Note:
1037 * A "clone" child here is one that reports to its parent
1038 * using a signal other than SIGCHLD.) */
1039 if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1040 && !(options & __WALL))
1041 return 0;
1042 /*
1043 * Do not consider thread group leaders that are
1044 * in a non-empty thread group:
1045 */
1046 if (current->tgid != p->tgid && delay_group_leader(p))
1047 return 2;
1048
1049 if (security_task_wait(p))
1050 return 0;
1051
1052 return 1;
1053 }
1054
1055 static int wait_noreap_copyout(task_t *p, pid_t pid, uid_t uid,
1056 int why, int status,
1057 struct siginfo __user *infop,
1058 struct rusage __user *rusagep)
1059 {
1060 int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1061 put_task_struct(p);
1062 if (!retval)
1063 retval = put_user(SIGCHLD, &infop->si_signo);
1064 if (!retval)
1065 retval = put_user(0, &infop->si_errno);
1066 if (!retval)
1067 retval = put_user((short)why, &infop->si_code);
1068 if (!retval)
1069 retval = put_user(pid, &infop->si_pid);
1070 if (!retval)
1071 retval = put_user(uid, &infop->si_uid);
1072 if (!retval)
1073 retval = put_user(status, &infop->si_status);
1074 if (!retval)
1075 retval = pid;
1076 return retval;
1077 }
1078
1079 /*
1080 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1081 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1082 * the lock and this task is uninteresting. If we return nonzero, we have
1083 * released the lock and the system call should return.
1084 */
1085 static int wait_task_zombie(task_t *p, int noreap,
1086 struct siginfo __user *infop,
1087 int __user *stat_addr, struct rusage __user *ru)
1088 {
1089 unsigned long state;
1090 int retval;
1091 int status;
1092
1093 if (unlikely(noreap)) {
1094 pid_t pid = p->pid;
1095 uid_t uid = p->uid;
1096 int exit_code = p->exit_code;
1097 int why, status;
1098
1099 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1100 return 0;
1101 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1102 return 0;
1103 get_task_struct(p);
1104 read_unlock(&tasklist_lock);
1105 if ((exit_code & 0x7f) == 0) {
1106 why = CLD_EXITED;
1107 status = exit_code >> 8;
1108 } else {
1109 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1110 status = exit_code & 0x7f;
1111 }
1112 return wait_noreap_copyout(p, pid, uid, why,
1113 status, infop, ru);
1114 }
1115
1116 /*
1117 * Try to move the task's state to DEAD
1118 * only one thread is allowed to do this:
1119 */
1120 state = xchg(&p->exit_state, EXIT_DEAD);
1121 if (state != EXIT_ZOMBIE) {
1122 BUG_ON(state != EXIT_DEAD);
1123 return 0;
1124 }
1125 if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1126 /*
1127 * This can only happen in a race with a ptraced thread
1128 * dying on another processor.
1129 */
1130 return 0;
1131 }
1132
1133 if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1134 struct signal_struct *psig;
1135 struct signal_struct *sig;
1136
1137 /*
1138 * The resource counters for the group leader are in its
1139 * own task_struct. Those for dead threads in the group
1140 * are in its signal_struct, as are those for the child
1141 * processes it has previously reaped. All these
1142 * accumulate in the parent's signal_struct c* fields.
1143 *
1144 * We don't bother to take a lock here to protect these
1145 * p->signal fields, because they are only touched by
1146 * __exit_signal, which runs with tasklist_lock
1147 * write-locked anyway, and so is excluded here. We do
1148 * need to protect the access to p->parent->signal fields,
1149 * as other threads in the parent group can be right
1150 * here reaping other children at the same time.
1151 */
1152 spin_lock_irq(&p->parent->sighand->siglock);
1153 psig = p->parent->signal;
1154 sig = p->signal;
1155 psig->cutime =
1156 cputime_add(psig->cutime,
1157 cputime_add(p->utime,
1158 cputime_add(sig->utime,
1159 sig->cutime)));
1160 psig->cstime =
1161 cputime_add(psig->cstime,
1162 cputime_add(p->stime,
1163 cputime_add(sig->stime,
1164 sig->cstime)));
1165 psig->cmin_flt +=
1166 p->min_flt + sig->min_flt + sig->cmin_flt;
1167 psig->cmaj_flt +=
1168 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1169 psig->cnvcsw +=
1170 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1171 psig->cnivcsw +=
1172 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1173 spin_unlock_irq(&p->parent->sighand->siglock);
1174 }
1175
1176 /*
1177 * Now we are sure this task is interesting, and no other
1178 * thread can reap it because we set its state to EXIT_DEAD.
1179 */
1180 read_unlock(&tasklist_lock);
1181
1182 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1183 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1184 ? p->signal->group_exit_code : p->exit_code;
1185 if (!retval && stat_addr)
1186 retval = put_user(status, stat_addr);
1187 if (!retval && infop)
1188 retval = put_user(SIGCHLD, &infop->si_signo);
1189 if (!retval && infop)
1190 retval = put_user(0, &infop->si_errno);
1191 if (!retval && infop) {
1192 int why;
1193
1194 if ((status & 0x7f) == 0) {
1195 why = CLD_EXITED;
1196 status >>= 8;
1197 } else {
1198 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1199 status &= 0x7f;
1200 }
1201 retval = put_user((short)why, &infop->si_code);
1202 if (!retval)
1203 retval = put_user(status, &infop->si_status);
1204 }
1205 if (!retval && infop)
1206 retval = put_user(p->pid, &infop->si_pid);
1207 if (!retval && infop)
1208 retval = put_user(p->uid, &infop->si_uid);
1209 if (retval) {
1210 // TODO: is this safe?
1211 p->exit_state = EXIT_ZOMBIE;
1212 return retval;
1213 }
1214 retval = p->pid;
1215 if (p->real_parent != p->parent) {
1216 write_lock_irq(&tasklist_lock);
1217 /* Double-check with lock held. */
1218 if (p->real_parent != p->parent) {
1219 __ptrace_unlink(p);
1220 // TODO: is this safe?
1221 p->exit_state = EXIT_ZOMBIE;
1222 /*
1223 * If this is not a detached task, notify the parent.
1224 * If it's still not detached after that, don't release
1225 * it now.
1226 */
1227 if (p->exit_signal != -1) {
1228 do_notify_parent(p, p->exit_signal);
1229 if (p->exit_signal != -1)
1230 p = NULL;
1231 }
1232 }
1233 write_unlock_irq(&tasklist_lock);
1234 }
1235 if (p != NULL)
1236 release_task(p);
1237 BUG_ON(!retval);
1238 return retval;
1239 }
1240
1241 /*
1242 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1243 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1244 * the lock and this task is uninteresting. If we return nonzero, we have
1245 * released the lock and the system call should return.
1246 */
1247 static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap,
1248 struct siginfo __user *infop,
1249 int __user *stat_addr, struct rusage __user *ru)
1250 {
1251 int retval, exit_code;
1252
1253 if (!p->exit_code)
1254 return 0;
1255 if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1256 p->signal && p->signal->group_stop_count > 0)
1257 /*
1258 * A group stop is in progress and this is the group leader.
1259 * We won't report until all threads have stopped.
1260 */
1261 return 0;
1262
1263 /*
1264 * Now we are pretty sure this task is interesting.
1265 * Make sure it doesn't get reaped out from under us while we
1266 * give up the lock and then examine it below. We don't want to
1267 * keep holding onto the tasklist_lock while we call getrusage and
1268 * possibly take page faults for user memory.
1269 */
1270 get_task_struct(p);
1271 read_unlock(&tasklist_lock);
1272
1273 if (unlikely(noreap)) {
1274 pid_t pid = p->pid;
1275 uid_t uid = p->uid;
1276 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1277
1278 exit_code = p->exit_code;
1279 if (unlikely(!exit_code) ||
1280 unlikely(p->state & TASK_TRACED))
1281 goto bail_ref;
1282 return wait_noreap_copyout(p, pid, uid,
1283 why, (exit_code << 8) | 0x7f,
1284 infop, ru);
1285 }
1286
1287 write_lock_irq(&tasklist_lock);
1288
1289 /*
1290 * This uses xchg to be atomic with the thread resuming and setting
1291 * it. It must also be done with the write lock held to prevent a
1292 * race with the EXIT_ZOMBIE case.
1293 */
1294 exit_code = xchg(&p->exit_code, 0);
1295 if (unlikely(p->exit_state)) {
1296 /*
1297 * The task resumed and then died. Let the next iteration
1298 * catch it in EXIT_ZOMBIE. Note that exit_code might
1299 * already be zero here if it resumed and did _exit(0).
1300 * The task itself is dead and won't touch exit_code again;
1301 * other processors in this function are locked out.
1302 */
1303 p->exit_code = exit_code;
1304 exit_code = 0;
1305 }
1306 if (unlikely(exit_code == 0)) {
1307 /*
1308 * Another thread in this function got to it first, or it
1309 * resumed, or it resumed and then died.
1310 */
1311 write_unlock_irq(&tasklist_lock);
1312 bail_ref:
1313 put_task_struct(p);
1314 /*
1315 * We are returning to the wait loop without having successfully
1316 * removed the process and having released the lock. We cannot
1317 * continue, since the "p" task pointer is potentially stale.
1318 *
1319 * Return -EAGAIN, and do_wait() will restart the loop from the
1320 * beginning. Do _not_ re-acquire the lock.
1321 */
1322 return -EAGAIN;
1323 }
1324
1325 /* move to end of parent's list to avoid starvation */
1326 remove_parent(p);
1327 add_parent(p);
1328
1329 write_unlock_irq(&tasklist_lock);
1330
1331 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1332 if (!retval && stat_addr)
1333 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1334 if (!retval && infop)
1335 retval = put_user(SIGCHLD, &infop->si_signo);
1336 if (!retval && infop)
1337 retval = put_user(0, &infop->si_errno);
1338 if (!retval && infop)
1339 retval = put_user((short)((p->ptrace & PT_PTRACED)
1340 ? CLD_TRAPPED : CLD_STOPPED),
1341 &infop->si_code);
1342 if (!retval && infop)
1343 retval = put_user(exit_code, &infop->si_status);
1344 if (!retval && infop)
1345 retval = put_user(p->pid, &infop->si_pid);
1346 if (!retval && infop)
1347 retval = put_user(p->uid, &infop->si_uid);
1348 if (!retval)
1349 retval = p->pid;
1350 put_task_struct(p);
1351
1352 BUG_ON(!retval);
1353 return retval;
1354 }
1355
1356 /*
1357 * Handle do_wait work for one task in a live, non-stopped state.
1358 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1359 * the lock and this task is uninteresting. If we return nonzero, we have
1360 * released the lock and the system call should return.
1361 */
1362 static int wait_task_continued(task_t *p, int noreap,
1363 struct siginfo __user *infop,
1364 int __user *stat_addr, struct rusage __user *ru)
1365 {
1366 int retval;
1367 pid_t pid;
1368 uid_t uid;
1369
1370 if (unlikely(!p->signal))
1371 return 0;
1372
1373 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1374 return 0;
1375
1376 spin_lock_irq(&p->sighand->siglock);
1377 /* Re-check with the lock held. */
1378 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1379 spin_unlock_irq(&p->sighand->siglock);
1380 return 0;
1381 }
1382 if (!noreap)
1383 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1384 spin_unlock_irq(&p->sighand->siglock);
1385
1386 pid = p->pid;
1387 uid = p->uid;
1388 get_task_struct(p);
1389 read_unlock(&tasklist_lock);
1390
1391 if (!infop) {
1392 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1393 put_task_struct(p);
1394 if (!retval && stat_addr)
1395 retval = put_user(0xffff, stat_addr);
1396 if (!retval)
1397 retval = p->pid;
1398 } else {
1399 retval = wait_noreap_copyout(p, pid, uid,
1400 CLD_CONTINUED, SIGCONT,
1401 infop, ru);
1402 BUG_ON(retval == 0);
1403 }
1404
1405 return retval;
1406 }
1407
1408
1409 static inline int my_ptrace_child(struct task_struct *p)
1410 {
1411 if (!(p->ptrace & PT_PTRACED))
1412 return 0;
1413 if (!(p->ptrace & PT_ATTACHED))
1414 return 1;
1415 /*
1416 * This child was PTRACE_ATTACH'd. We should be seeing it only if
1417 * we are the attacher. If we are the real parent, this is a race
1418 * inside ptrace_attach. It is waiting for the tasklist_lock,
1419 * which we have to switch the parent links, but has already set
1420 * the flags in p->ptrace.
1421 */
1422 return (p->parent != p->real_parent);
1423 }
1424
1425 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1426 int __user *stat_addr, struct rusage __user *ru)
1427 {
1428 DECLARE_WAITQUEUE(wait, current);
1429 struct task_struct *tsk;
1430 int flag, retval;
1431
1432 add_wait_queue(&current->signal->wait_chldexit,&wait);
1433 repeat:
1434 /*
1435 * We will set this flag if we see any child that might later
1436 * match our criteria, even if we are not able to reap it yet.
1437 */
1438 flag = 0;
1439 current->state = TASK_INTERRUPTIBLE;
1440 read_lock(&tasklist_lock);
1441 tsk = current;
1442 do {
1443 struct task_struct *p;
1444 struct list_head *_p;
1445 int ret;
1446
1447 list_for_each(_p,&tsk->children) {
1448 p = list_entry(_p,struct task_struct,sibling);
1449
1450 ret = eligible_child(pid, options, p);
1451 if (!ret)
1452 continue;
1453
1454 switch (p->state) {
1455 case TASK_TRACED:
1456 /*
1457 * When we hit the race with PTRACE_ATTACH,
1458 * we will not report this child. But the
1459 * race means it has not yet been moved to
1460 * our ptrace_children list, so we need to
1461 * set the flag here to avoid a spurious ECHILD
1462 * when the race happens with the only child.
1463 */
1464 flag = 1;
1465 if (!my_ptrace_child(p))
1466 continue;
1467 /*FALLTHROUGH*/
1468 case TASK_STOPPED:
1469 /*
1470 * It's stopped now, so it might later
1471 * continue, exit, or stop again.
1472 */
1473 flag = 1;
1474 if (!(options & WUNTRACED) &&
1475 !my_ptrace_child(p))
1476 continue;
1477 retval = wait_task_stopped(p, ret == 2,
1478 (options & WNOWAIT),
1479 infop,
1480 stat_addr, ru);
1481 if (retval == -EAGAIN)
1482 goto repeat;
1483 if (retval != 0) /* He released the lock. */
1484 goto end;
1485 break;
1486 default:
1487 // case EXIT_DEAD:
1488 if (p->exit_state == EXIT_DEAD)
1489 continue;
1490 // case EXIT_ZOMBIE:
1491 if (p->exit_state == EXIT_ZOMBIE) {
1492 /*
1493 * Eligible but we cannot release
1494 * it yet:
1495 */
1496 if (ret == 2)
1497 goto check_continued;
1498 if (!likely(options & WEXITED))
1499 continue;
1500 retval = wait_task_zombie(
1501 p, (options & WNOWAIT),
1502 infop, stat_addr, ru);
1503 /* He released the lock. */
1504 if (retval != 0)
1505 goto end;
1506 break;
1507 }
1508 check_continued:
1509 /*
1510 * It's running now, so it might later
1511 * exit, stop, or stop and then continue.
1512 */
1513 flag = 1;
1514 if (!unlikely(options & WCONTINUED))
1515 continue;
1516 retval = wait_task_continued(
1517 p, (options & WNOWAIT),
1518 infop, stat_addr, ru);
1519 if (retval != 0) /* He released the lock. */
1520 goto end;
1521 break;
1522 }
1523 }
1524 if (!flag) {
1525 list_for_each(_p, &tsk->ptrace_children) {
1526 p = list_entry(_p, struct task_struct,
1527 ptrace_list);
1528 if (!eligible_child(pid, options, p))
1529 continue;
1530 flag = 1;
1531 break;
1532 }
1533 }
1534 if (options & __WNOTHREAD)
1535 break;
1536 tsk = next_thread(tsk);
1537 BUG_ON(tsk->signal != current->signal);
1538 } while (tsk != current);
1539
1540 read_unlock(&tasklist_lock);
1541 if (flag) {
1542 retval = 0;
1543 if (options & WNOHANG)
1544 goto end;
1545 retval = -ERESTARTSYS;
1546 if (signal_pending(current))
1547 goto end;
1548 schedule();
1549 goto repeat;
1550 }
1551 retval = -ECHILD;
1552 end:
1553 current->state = TASK_RUNNING;
1554 remove_wait_queue(&current->signal->wait_chldexit,&wait);
1555 if (infop) {
1556 if (retval > 0)
1557 retval = 0;
1558 else {
1559 /*
1560 * For a WNOHANG return, clear out all the fields
1561 * we would set so the user can easily tell the
1562 * difference.
1563 */
1564 if (!retval)
1565 retval = put_user(0, &infop->si_signo);
1566 if (!retval)
1567 retval = put_user(0, &infop->si_errno);
1568 if (!retval)
1569 retval = put_user(0, &infop->si_code);
1570 if (!retval)
1571 retval = put_user(0, &infop->si_pid);
1572 if (!retval)
1573 retval = put_user(0, &infop->si_uid);
1574 if (!retval)
1575 retval = put_user(0, &infop->si_status);
1576 }
1577 }
1578 return retval;
1579 }
1580
1581 asmlinkage long sys_waitid(int which, pid_t pid,
1582 struct siginfo __user *infop, int options,
1583 struct rusage __user *ru)
1584 {
1585 long ret;
1586
1587 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1588 return -EINVAL;
1589 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1590 return -EINVAL;
1591
1592 switch (which) {
1593 case P_ALL:
1594 pid = -1;
1595 break;
1596 case P_PID:
1597 if (pid <= 0)
1598 return -EINVAL;
1599 break;
1600 case P_PGID:
1601 if (pid <= 0)
1602 return -EINVAL;
1603 pid = -pid;
1604 break;
1605 default:
1606 return -EINVAL;
1607 }
1608
1609 ret = do_wait(pid, options, infop, NULL, ru);
1610
1611 /* avoid REGPARM breakage on x86: */
1612 prevent_tail_call(ret);
1613 return ret;
1614 }
1615
1616 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1617 int options, struct rusage __user *ru)
1618 {
1619 long ret;
1620
1621 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1622 __WNOTHREAD|__WCLONE|__WALL))
1623 return -EINVAL;
1624 ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1625
1626 /* avoid REGPARM breakage on x86: */
1627 prevent_tail_call(ret);
1628 return ret;
1629 }
1630
1631 #ifdef __ARCH_WANT_SYS_WAITPID
1632
1633 /*
1634 * sys_waitpid() remains for compatibility. waitpid() should be
1635 * implemented by calling sys_wait4() from libc.a.
1636 */
1637 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1638 {
1639 return sys_wait4(pid, stat_addr, options, NULL);
1640 }
1641
1642 #endif