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1 /*
2 * linux/kernel/exit.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7 #include <linux/config.h>
8 #include <linux/mm.h>
9 #include <linux/slab.h>
10 #include <linux/interrupt.h>
11 #include <linux/smp_lock.h>
12 #include <linux/module.h>
13 #include <linux/capability.h>
14 #include <linux/completion.h>
15 #include <linux/personality.h>
16 #include <linux/tty.h>
17 #include <linux/namespace.h>
18 #include <linux/key.h>
19 #include <linux/security.h>
20 #include <linux/cpu.h>
21 #include <linux/acct.h>
22 #include <linux/file.h>
23 #include <linux/binfmts.h>
24 #include <linux/ptrace.h>
25 #include <linux/profile.h>
26 #include <linux/mount.h>
27 #include <linux/proc_fs.h>
28 #include <linux/mempolicy.h>
29 #include <linux/cpuset.h>
30 #include <linux/syscalls.h>
31 #include <linux/signal.h>
32 #include <linux/posix-timers.h>
33 #include <linux/cn_proc.h>
34 #include <linux/mutex.h>
35 #include <linux/futex.h>
36 #include <linux/compat.h>
37 #include <linux/pipe_fs_i.h>
38 #include <linux/audit.h> /* for audit_free() */
39 #include <linux/resource.h>
40
41 #include <asm/uaccess.h>
42 #include <asm/unistd.h>
43 #include <asm/pgtable.h>
44 #include <asm/mmu_context.h>
45
46 extern void sem_exit (void);
47 extern struct task_struct *child_reaper;
48
49 static void exit_mm(struct task_struct * tsk);
50
51 static void __unhash_process(struct task_struct *p)
52 {
53 nr_threads--;
54 detach_pid(p, PIDTYPE_PID);
55 if (thread_group_leader(p)) {
56 detach_pid(p, PIDTYPE_PGID);
57 detach_pid(p, PIDTYPE_SID);
58
59 list_del_rcu(&p->tasks);
60 __get_cpu_var(process_counts)--;
61 }
62 list_del_rcu(&p->thread_group);
63 remove_parent(p);
64 }
65
66 /*
67 * This function expects the tasklist_lock write-locked.
68 */
69 static void __exit_signal(struct task_struct *tsk)
70 {
71 struct signal_struct *sig = tsk->signal;
72 struct sighand_struct *sighand;
73
74 BUG_ON(!sig);
75 BUG_ON(!atomic_read(&sig->count));
76
77 rcu_read_lock();
78 sighand = rcu_dereference(tsk->sighand);
79 spin_lock(&sighand->siglock);
80
81 posix_cpu_timers_exit(tsk);
82 if (atomic_dec_and_test(&sig->count))
83 posix_cpu_timers_exit_group(tsk);
84 else {
85 /*
86 * If there is any task waiting for the group exit
87 * then notify it:
88 */
89 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
90 wake_up_process(sig->group_exit_task);
91 sig->group_exit_task = NULL;
92 }
93 if (tsk == sig->curr_target)
94 sig->curr_target = next_thread(tsk);
95 /*
96 * Accumulate here the counters for all threads but the
97 * group leader as they die, so they can be added into
98 * the process-wide totals when those are taken.
99 * The group leader stays around as a zombie as long
100 * as there are other threads. When it gets reaped,
101 * the exit.c code will add its counts into these totals.
102 * We won't ever get here for the group leader, since it
103 * will have been the last reference on the signal_struct.
104 */
105 sig->utime = cputime_add(sig->utime, tsk->utime);
106 sig->stime = cputime_add(sig->stime, tsk->stime);
107 sig->min_flt += tsk->min_flt;
108 sig->maj_flt += tsk->maj_flt;
109 sig->nvcsw += tsk->nvcsw;
110 sig->nivcsw += tsk->nivcsw;
111 sig->sched_time += tsk->sched_time;
112 sig = NULL; /* Marker for below. */
113 }
114
115 __unhash_process(tsk);
116
117 tsk->signal = NULL;
118 tsk->sighand = NULL;
119 spin_unlock(&sighand->siglock);
120 rcu_read_unlock();
121
122 __cleanup_sighand(sighand);
123 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
124 flush_sigqueue(&tsk->pending);
125 if (sig) {
126 flush_sigqueue(&sig->shared_pending);
127 __cleanup_signal(sig);
128 }
129 }
130
131 static void delayed_put_task_struct(struct rcu_head *rhp)
132 {
133 put_task_struct(container_of(rhp, struct task_struct, rcu));
134 }
135
136 void release_task(struct task_struct * p)
137 {
138 int zap_leader;
139 task_t *leader;
140 repeat:
141 atomic_dec(&p->user->processes);
142 write_lock_irq(&tasklist_lock);
143 ptrace_unlink(p);
144 BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
145 __exit_signal(p);
146
147 /*
148 * If we are the last non-leader member of the thread
149 * group, and the leader is zombie, then notify the
150 * group leader's parent process. (if it wants notification.)
151 */
152 zap_leader = 0;
153 leader = p->group_leader;
154 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
155 BUG_ON(leader->exit_signal == -1);
156 do_notify_parent(leader, leader->exit_signal);
157 /*
158 * If we were the last child thread and the leader has
159 * exited already, and the leader's parent ignores SIGCHLD,
160 * then we are the one who should release the leader.
161 *
162 * do_notify_parent() will have marked it self-reaping in
163 * that case.
164 */
165 zap_leader = (leader->exit_signal == -1);
166 }
167
168 sched_exit(p);
169 write_unlock_irq(&tasklist_lock);
170 proc_flush_task(p);
171 release_thread(p);
172 call_rcu(&p->rcu, delayed_put_task_struct);
173
174 p = leader;
175 if (unlikely(zap_leader))
176 goto repeat;
177 }
178
179 /*
180 * This checks not only the pgrp, but falls back on the pid if no
181 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
182 * without this...
183 */
184 int session_of_pgrp(int pgrp)
185 {
186 struct task_struct *p;
187 int sid = -1;
188
189 read_lock(&tasklist_lock);
190 do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
191 if (p->signal->session > 0) {
192 sid = p->signal->session;
193 goto out;
194 }
195 } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
196 p = find_task_by_pid(pgrp);
197 if (p)
198 sid = p->signal->session;
199 out:
200 read_unlock(&tasklist_lock);
201
202 return sid;
203 }
204
205 /*
206 * Determine if a process group is "orphaned", according to the POSIX
207 * definition in 2.2.2.52. Orphaned process groups are not to be affected
208 * by terminal-generated stop signals. Newly orphaned process groups are
209 * to receive a SIGHUP and a SIGCONT.
210 *
211 * "I ask you, have you ever known what it is to be an orphan?"
212 */
213 static int will_become_orphaned_pgrp(int pgrp, task_t *ignored_task)
214 {
215 struct task_struct *p;
216 int ret = 1;
217
218 do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
219 if (p == ignored_task
220 || p->exit_state
221 || p->real_parent->pid == 1)
222 continue;
223 if (process_group(p->real_parent) != pgrp
224 && p->real_parent->signal->session == p->signal->session) {
225 ret = 0;
226 break;
227 }
228 } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
229 return ret; /* (sighing) "Often!" */
230 }
231
232 int is_orphaned_pgrp(int pgrp)
233 {
234 int retval;
235
236 read_lock(&tasklist_lock);
237 retval = will_become_orphaned_pgrp(pgrp, NULL);
238 read_unlock(&tasklist_lock);
239
240 return retval;
241 }
242
243 static int has_stopped_jobs(int pgrp)
244 {
245 int retval = 0;
246 struct task_struct *p;
247
248 do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
249 if (p->state != TASK_STOPPED)
250 continue;
251
252 /* If p is stopped by a debugger on a signal that won't
253 stop it, then don't count p as stopped. This isn't
254 perfect but it's a good approximation. */
255 if (unlikely (p->ptrace)
256 && p->exit_code != SIGSTOP
257 && p->exit_code != SIGTSTP
258 && p->exit_code != SIGTTOU
259 && p->exit_code != SIGTTIN)
260 continue;
261
262 retval = 1;
263 break;
264 } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
265 return retval;
266 }
267
268 /**
269 * reparent_to_init - Reparent the calling kernel thread to the init task.
270 *
271 * If a kernel thread is launched as a result of a system call, or if
272 * it ever exits, it should generally reparent itself to init so that
273 * it is correctly cleaned up on exit.
274 *
275 * The various task state such as scheduling policy and priority may have
276 * been inherited from a user process, so we reset them to sane values here.
277 *
278 * NOTE that reparent_to_init() gives the caller full capabilities.
279 */
280 static void reparent_to_init(void)
281 {
282 write_lock_irq(&tasklist_lock);
283
284 ptrace_unlink(current);
285 /* Reparent to init */
286 remove_parent(current);
287 current->parent = child_reaper;
288 current->real_parent = child_reaper;
289 add_parent(current);
290
291 /* Set the exit signal to SIGCHLD so we signal init on exit */
292 current->exit_signal = SIGCHLD;
293
294 if ((current->policy == SCHED_NORMAL ||
295 current->policy == SCHED_BATCH)
296 && (task_nice(current) < 0))
297 set_user_nice(current, 0);
298 /* cpus_allowed? */
299 /* rt_priority? */
300 /* signals? */
301 security_task_reparent_to_init(current);
302 memcpy(current->signal->rlim, init_task.signal->rlim,
303 sizeof(current->signal->rlim));
304 atomic_inc(&(INIT_USER->__count));
305 write_unlock_irq(&tasklist_lock);
306 switch_uid(INIT_USER);
307 }
308
309 void __set_special_pids(pid_t session, pid_t pgrp)
310 {
311 struct task_struct *curr = current->group_leader;
312
313 if (curr->signal->session != session) {
314 detach_pid(curr, PIDTYPE_SID);
315 curr->signal->session = session;
316 attach_pid(curr, PIDTYPE_SID, session);
317 }
318 if (process_group(curr) != pgrp) {
319 detach_pid(curr, PIDTYPE_PGID);
320 curr->signal->pgrp = pgrp;
321 attach_pid(curr, PIDTYPE_PGID, pgrp);
322 }
323 }
324
325 void set_special_pids(pid_t session, pid_t pgrp)
326 {
327 write_lock_irq(&tasklist_lock);
328 __set_special_pids(session, pgrp);
329 write_unlock_irq(&tasklist_lock);
330 }
331
332 /*
333 * Let kernel threads use this to say that they
334 * allow a certain signal (since daemonize() will
335 * have disabled all of them by default).
336 */
337 int allow_signal(int sig)
338 {
339 if (!valid_signal(sig) || sig < 1)
340 return -EINVAL;
341
342 spin_lock_irq(&current->sighand->siglock);
343 sigdelset(&current->blocked, sig);
344 if (!current->mm) {
345 /* Kernel threads handle their own signals.
346 Let the signal code know it'll be handled, so
347 that they don't get converted to SIGKILL or
348 just silently dropped */
349 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
350 }
351 recalc_sigpending();
352 spin_unlock_irq(&current->sighand->siglock);
353 return 0;
354 }
355
356 EXPORT_SYMBOL(allow_signal);
357
358 int disallow_signal(int sig)
359 {
360 if (!valid_signal(sig) || sig < 1)
361 return -EINVAL;
362
363 spin_lock_irq(&current->sighand->siglock);
364 sigaddset(&current->blocked, sig);
365 recalc_sigpending();
366 spin_unlock_irq(&current->sighand->siglock);
367 return 0;
368 }
369
370 EXPORT_SYMBOL(disallow_signal);
371
372 /*
373 * Put all the gunge required to become a kernel thread without
374 * attached user resources in one place where it belongs.
375 */
376
377 void daemonize(const char *name, ...)
378 {
379 va_list args;
380 struct fs_struct *fs;
381 sigset_t blocked;
382
383 va_start(args, name);
384 vsnprintf(current->comm, sizeof(current->comm), name, args);
385 va_end(args);
386
387 /*
388 * If we were started as result of loading a module, close all of the
389 * user space pages. We don't need them, and if we didn't close them
390 * they would be locked into memory.
391 */
392 exit_mm(current);
393
394 set_special_pids(1, 1);
395 mutex_lock(&tty_mutex);
396 current->signal->tty = NULL;
397 mutex_unlock(&tty_mutex);
398
399 /* Block and flush all signals */
400 sigfillset(&blocked);
401 sigprocmask(SIG_BLOCK, &blocked, NULL);
402 flush_signals(current);
403
404 /* Become as one with the init task */
405
406 exit_fs(current); /* current->fs->count--; */
407 fs = init_task.fs;
408 current->fs = fs;
409 atomic_inc(&fs->count);
410 exit_namespace(current);
411 current->namespace = init_task.namespace;
412 get_namespace(current->namespace);
413 exit_files(current);
414 current->files = init_task.files;
415 atomic_inc(&current->files->count);
416
417 reparent_to_init();
418 }
419
420 EXPORT_SYMBOL(daemonize);
421
422 static void close_files(struct files_struct * files)
423 {
424 int i, j;
425 struct fdtable *fdt;
426
427 j = 0;
428
429 /*
430 * It is safe to dereference the fd table without RCU or
431 * ->file_lock because this is the last reference to the
432 * files structure.
433 */
434 fdt = files_fdtable(files);
435 for (;;) {
436 unsigned long set;
437 i = j * __NFDBITS;
438 if (i >= fdt->max_fdset || i >= fdt->max_fds)
439 break;
440 set = fdt->open_fds->fds_bits[j++];
441 while (set) {
442 if (set & 1) {
443 struct file * file = xchg(&fdt->fd[i], NULL);
444 if (file)
445 filp_close(file, files);
446 }
447 i++;
448 set >>= 1;
449 }
450 }
451 }
452
453 struct files_struct *get_files_struct(struct task_struct *task)
454 {
455 struct files_struct *files;
456
457 task_lock(task);
458 files = task->files;
459 if (files)
460 atomic_inc(&files->count);
461 task_unlock(task);
462
463 return files;
464 }
465
466 void fastcall put_files_struct(struct files_struct *files)
467 {
468 struct fdtable *fdt;
469
470 if (atomic_dec_and_test(&files->count)) {
471 close_files(files);
472 /*
473 * Free the fd and fdset arrays if we expanded them.
474 * If the fdtable was embedded, pass files for freeing
475 * at the end of the RCU grace period. Otherwise,
476 * you can free files immediately.
477 */
478 fdt = files_fdtable(files);
479 if (fdt == &files->fdtab)
480 fdt->free_files = files;
481 else
482 kmem_cache_free(files_cachep, files);
483 free_fdtable(fdt);
484 }
485 }
486
487 EXPORT_SYMBOL(put_files_struct);
488
489 static inline void __exit_files(struct task_struct *tsk)
490 {
491 struct files_struct * files = tsk->files;
492
493 if (files) {
494 task_lock(tsk);
495 tsk->files = NULL;
496 task_unlock(tsk);
497 put_files_struct(files);
498 }
499 }
500
501 void exit_files(struct task_struct *tsk)
502 {
503 __exit_files(tsk);
504 }
505
506 static inline void __put_fs_struct(struct fs_struct *fs)
507 {
508 /* No need to hold fs->lock if we are killing it */
509 if (atomic_dec_and_test(&fs->count)) {
510 dput(fs->root);
511 mntput(fs->rootmnt);
512 dput(fs->pwd);
513 mntput(fs->pwdmnt);
514 if (fs->altroot) {
515 dput(fs->altroot);
516 mntput(fs->altrootmnt);
517 }
518 kmem_cache_free(fs_cachep, fs);
519 }
520 }
521
522 void put_fs_struct(struct fs_struct *fs)
523 {
524 __put_fs_struct(fs);
525 }
526
527 static inline void __exit_fs(struct task_struct *tsk)
528 {
529 struct fs_struct * fs = tsk->fs;
530
531 if (fs) {
532 task_lock(tsk);
533 tsk->fs = NULL;
534 task_unlock(tsk);
535 __put_fs_struct(fs);
536 }
537 }
538
539 void exit_fs(struct task_struct *tsk)
540 {
541 __exit_fs(tsk);
542 }
543
544 EXPORT_SYMBOL_GPL(exit_fs);
545
546 /*
547 * Turn us into a lazy TLB process if we
548 * aren't already..
549 */
550 static void exit_mm(struct task_struct * tsk)
551 {
552 struct mm_struct *mm = tsk->mm;
553
554 mm_release(tsk, mm);
555 if (!mm)
556 return;
557 /*
558 * Serialize with any possible pending coredump.
559 * We must hold mmap_sem around checking core_waiters
560 * and clearing tsk->mm. The core-inducing thread
561 * will increment core_waiters for each thread in the
562 * group with ->mm != NULL.
563 */
564 down_read(&mm->mmap_sem);
565 if (mm->core_waiters) {
566 up_read(&mm->mmap_sem);
567 down_write(&mm->mmap_sem);
568 if (!--mm->core_waiters)
569 complete(mm->core_startup_done);
570 up_write(&mm->mmap_sem);
571
572 wait_for_completion(&mm->core_done);
573 down_read(&mm->mmap_sem);
574 }
575 atomic_inc(&mm->mm_count);
576 BUG_ON(mm != tsk->active_mm);
577 /* more a memory barrier than a real lock */
578 task_lock(tsk);
579 tsk->mm = NULL;
580 up_read(&mm->mmap_sem);
581 enter_lazy_tlb(mm, current);
582 task_unlock(tsk);
583 mmput(mm);
584 }
585
586 static inline void choose_new_parent(task_t *p, task_t *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 reparent_thread(task_t *p, task_t *father, int traced)
597 {
598 /* We don't want people slaying init. */
599 if (p->exit_signal != -1)
600 p->exit_signal = SIGCHLD;
601
602 if (p->pdeath_signal)
603 /* We already hold the tasklist_lock here. */
604 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
605
606 /* Move the child from its dying parent to the new one. */
607 if (unlikely(traced)) {
608 /* Preserve ptrace links if someone else is tracing this child. */
609 list_del_init(&p->ptrace_list);
610 if (p->parent != p->real_parent)
611 list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
612 } else {
613 /* If this child is being traced, then we're the one tracing it
614 * anyway, so let go of it.
615 */
616 p->ptrace = 0;
617 remove_parent(p);
618 p->parent = p->real_parent;
619 add_parent(p);
620
621 /* If we'd notified the old parent about this child's death,
622 * also notify the new parent.
623 */
624 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
625 thread_group_empty(p))
626 do_notify_parent(p, p->exit_signal);
627 else if (p->state == TASK_TRACED) {
628 /*
629 * If it was at a trace stop, turn it into
630 * a normal stop since it's no longer being
631 * traced.
632 */
633 ptrace_untrace(p);
634 }
635 }
636
637 /*
638 * process group orphan check
639 * Case ii: Our child is in a different pgrp
640 * than we are, and it was the only connection
641 * outside, so the child pgrp is now orphaned.
642 */
643 if ((process_group(p) != process_group(father)) &&
644 (p->signal->session == father->signal->session)) {
645 int pgrp = process_group(p);
646
647 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
648 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
649 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
650 }
651 }
652 }
653
654 /*
655 * When we die, we re-parent all our children.
656 * Try to give them to another thread in our thread
657 * group, and if no such member exists, give it to
658 * the global child reaper process (ie "init")
659 */
660 static void forget_original_parent(struct task_struct * father,
661 struct list_head *to_release)
662 {
663 struct task_struct *p, *reaper = father;
664 struct list_head *_p, *_n;
665
666 do {
667 reaper = next_thread(reaper);
668 if (reaper == father) {
669 reaper = child_reaper;
670 break;
671 }
672 } while (reaper->exit_state);
673
674 /*
675 * There are only two places where our children can be:
676 *
677 * - in our child list
678 * - in our ptraced child list
679 *
680 * Search them and reparent children.
681 */
682 list_for_each_safe(_p, _n, &father->children) {
683 int ptrace;
684 p = list_entry(_p,struct task_struct,sibling);
685
686 ptrace = p->ptrace;
687
688 /* if father isn't the real parent, then ptrace must be enabled */
689 BUG_ON(father != p->real_parent && !ptrace);
690
691 if (father == p->real_parent) {
692 /* reparent with a reaper, real father it's us */
693 choose_new_parent(p, reaper);
694 reparent_thread(p, father, 0);
695 } else {
696 /* reparent ptraced task to its real parent */
697 __ptrace_unlink (p);
698 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
699 thread_group_empty(p))
700 do_notify_parent(p, p->exit_signal);
701 }
702
703 /*
704 * if the ptraced child is a zombie with exit_signal == -1
705 * we must collect it before we exit, or it will remain
706 * zombie forever since we prevented it from self-reap itself
707 * while it was being traced by us, to be able to see it in wait4.
708 */
709 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
710 list_add(&p->ptrace_list, to_release);
711 }
712 list_for_each_safe(_p, _n, &father->ptrace_children) {
713 p = list_entry(_p,struct task_struct,ptrace_list);
714 choose_new_parent(p, reaper);
715 reparent_thread(p, father, 1);
716 }
717 }
718
719 /*
720 * Send signals to all our closest relatives so that they know
721 * to properly mourn us..
722 */
723 static void exit_notify(struct task_struct *tsk)
724 {
725 int state;
726 struct task_struct *t;
727 struct list_head ptrace_dead, *_p, *_n;
728
729 if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
730 && !thread_group_empty(tsk)) {
731 /*
732 * This occurs when there was a race between our exit
733 * syscall and a group signal choosing us as the one to
734 * wake up. It could be that we are the only thread
735 * alerted to check for pending signals, but another thread
736 * should be woken now to take the signal since we will not.
737 * Now we'll wake all the threads in the group just to make
738 * sure someone gets all the pending signals.
739 */
740 read_lock(&tasklist_lock);
741 spin_lock_irq(&tsk->sighand->siglock);
742 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
743 if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
744 recalc_sigpending_tsk(t);
745 if (signal_pending(t))
746 signal_wake_up(t, 0);
747 }
748 spin_unlock_irq(&tsk->sighand->siglock);
749 read_unlock(&tasklist_lock);
750 }
751
752 write_lock_irq(&tasklist_lock);
753
754 /*
755 * This does two things:
756 *
757 * A. Make init inherit all the child processes
758 * B. Check to see if any process groups have become orphaned
759 * as a result of our exiting, and if they have any stopped
760 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
761 */
762
763 INIT_LIST_HEAD(&ptrace_dead);
764 forget_original_parent(tsk, &ptrace_dead);
765 BUG_ON(!list_empty(&tsk->children));
766 BUG_ON(!list_empty(&tsk->ptrace_children));
767
768 /*
769 * Check to see if any process groups have become orphaned
770 * as a result of our exiting, and if they have any stopped
771 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
772 *
773 * Case i: Our father is in a different pgrp than we are
774 * and we were the only connection outside, so our pgrp
775 * is about to become orphaned.
776 */
777
778 t = tsk->real_parent;
779
780 if ((process_group(t) != process_group(tsk)) &&
781 (t->signal->session == tsk->signal->session) &&
782 will_become_orphaned_pgrp(process_group(tsk), tsk) &&
783 has_stopped_jobs(process_group(tsk))) {
784 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
785 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
786 }
787
788 /* Let father know we died
789 *
790 * Thread signals are configurable, but you aren't going to use
791 * that to send signals to arbitary processes.
792 * That stops right now.
793 *
794 * If the parent exec id doesn't match the exec id we saved
795 * when we started then we know the parent has changed security
796 * domain.
797 *
798 * If our self_exec id doesn't match our parent_exec_id then
799 * we have changed execution domain as these two values started
800 * the same after a fork.
801 *
802 */
803
804 if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
805 ( tsk->parent_exec_id != t->self_exec_id ||
806 tsk->self_exec_id != tsk->parent_exec_id)
807 && !capable(CAP_KILL))
808 tsk->exit_signal = SIGCHLD;
809
810
811 /* If something other than our normal parent is ptracing us, then
812 * send it a SIGCHLD instead of honoring exit_signal. exit_signal
813 * only has special meaning to our real parent.
814 */
815 if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
816 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
817 do_notify_parent(tsk, signal);
818 } else if (tsk->ptrace) {
819 do_notify_parent(tsk, SIGCHLD);
820 }
821
822 state = EXIT_ZOMBIE;
823 if (tsk->exit_signal == -1 &&
824 (likely(tsk->ptrace == 0) ||
825 unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
826 state = EXIT_DEAD;
827 tsk->exit_state = state;
828
829 write_unlock_irq(&tasklist_lock);
830
831 list_for_each_safe(_p, _n, &ptrace_dead) {
832 list_del_init(_p);
833 t = list_entry(_p,struct task_struct,ptrace_list);
834 release_task(t);
835 }
836
837 /* If the process is dead, release it - nobody will wait for it */
838 if (state == EXIT_DEAD)
839 release_task(tsk);
840 }
841
842 fastcall NORET_TYPE void do_exit(long code)
843 {
844 struct task_struct *tsk = current;
845 int group_dead;
846
847 profile_task_exit(tsk);
848
849 WARN_ON(atomic_read(&tsk->fs_excl));
850
851 if (unlikely(in_interrupt()))
852 panic("Aiee, killing interrupt handler!");
853 if (unlikely(!tsk->pid))
854 panic("Attempted to kill the idle task!");
855 if (unlikely(tsk == child_reaper))
856 panic("Attempted to kill init!");
857
858 if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
859 current->ptrace_message = code;
860 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
861 }
862
863 /*
864 * We're taking recursive faults here in do_exit. Safest is to just
865 * leave this task alone and wait for reboot.
866 */
867 if (unlikely(tsk->flags & PF_EXITING)) {
868 printk(KERN_ALERT
869 "Fixing recursive fault but reboot is needed!\n");
870 if (tsk->io_context)
871 exit_io_context();
872 set_current_state(TASK_UNINTERRUPTIBLE);
873 schedule();
874 }
875
876 tsk->flags |= PF_EXITING;
877
878 if (unlikely(in_atomic()))
879 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
880 current->comm, current->pid,
881 preempt_count());
882
883 acct_update_integrals(tsk);
884 if (tsk->mm) {
885 update_hiwater_rss(tsk->mm);
886 update_hiwater_vm(tsk->mm);
887 }
888 group_dead = atomic_dec_and_test(&tsk->signal->live);
889 if (group_dead) {
890 hrtimer_cancel(&tsk->signal->real_timer);
891 exit_itimers(tsk->signal);
892 }
893 acct_collect(code, group_dead);
894 if (unlikely(tsk->robust_list))
895 exit_robust_list(tsk);
896 #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
897 if (unlikely(tsk->compat_robust_list))
898 compat_exit_robust_list(tsk);
899 #endif
900 if (unlikely(tsk->audit_context))
901 audit_free(tsk);
902 exit_mm(tsk);
903
904 if (group_dead)
905 acct_process();
906 exit_sem(tsk);
907 __exit_files(tsk);
908 __exit_fs(tsk);
909 exit_namespace(tsk);
910 exit_thread();
911 cpuset_exit(tsk);
912 exit_keys(tsk);
913
914 if (group_dead && tsk->signal->leader)
915 disassociate_ctty(1);
916
917 module_put(task_thread_info(tsk)->exec_domain->module);
918 if (tsk->binfmt)
919 module_put(tsk->binfmt->module);
920
921 tsk->exit_code = code;
922 proc_exit_connector(tsk);
923 exit_notify(tsk);
924 #ifdef CONFIG_NUMA
925 mpol_free(tsk->mempolicy);
926 tsk->mempolicy = NULL;
927 #endif
928 /*
929 * This must happen late, after the PID is not
930 * hashed anymore:
931 */
932 if (unlikely(!list_empty(&tsk->pi_state_list)))
933 exit_pi_state_list(tsk);
934 if (unlikely(current->pi_state_cache))
935 kfree(current->pi_state_cache);
936 /*
937 * If DEBUG_MUTEXES is on, make sure we are holding no locks:
938 */
939 mutex_debug_check_no_locks_held(tsk);
940 rt_mutex_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, task_t *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(task_t *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 put_task_struct(p);
1063 if (!retval)
1064 retval = put_user(SIGCHLD, &infop->si_signo);
1065 if (!retval)
1066 retval = put_user(0, &infop->si_errno);
1067 if (!retval)
1068 retval = put_user((short)why, &infop->si_code);
1069 if (!retval)
1070 retval = put_user(pid, &infop->si_pid);
1071 if (!retval)
1072 retval = put_user(uid, &infop->si_uid);
1073 if (!retval)
1074 retval = put_user(status, &infop->si_status);
1075 if (!retval)
1076 retval = pid;
1077 return retval;
1078 }
1079
1080 /*
1081 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1082 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1083 * the lock and this task is uninteresting. If we return nonzero, we have
1084 * released the lock and the system call should return.
1085 */
1086 static int wait_task_zombie(task_t *p, int noreap,
1087 struct siginfo __user *infop,
1088 int __user *stat_addr, struct rusage __user *ru)
1089 {
1090 unsigned long state;
1091 int retval;
1092 int status;
1093
1094 if (unlikely(noreap)) {
1095 pid_t pid = p->pid;
1096 uid_t uid = p->uid;
1097 int exit_code = p->exit_code;
1098 int why, status;
1099
1100 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1101 return 0;
1102 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1103 return 0;
1104 get_task_struct(p);
1105 read_unlock(&tasklist_lock);
1106 if ((exit_code & 0x7f) == 0) {
1107 why = CLD_EXITED;
1108 status = exit_code >> 8;
1109 } else {
1110 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1111 status = exit_code & 0x7f;
1112 }
1113 return wait_noreap_copyout(p, pid, uid, why,
1114 status, infop, ru);
1115 }
1116
1117 /*
1118 * Try to move the task's state to DEAD
1119 * only one thread is allowed to do this:
1120 */
1121 state = xchg(&p->exit_state, EXIT_DEAD);
1122 if (state != EXIT_ZOMBIE) {
1123 BUG_ON(state != EXIT_DEAD);
1124 return 0;
1125 }
1126 if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1127 /*
1128 * This can only happen in a race with a ptraced thread
1129 * dying on another processor.
1130 */
1131 return 0;
1132 }
1133
1134 if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1135 struct signal_struct *psig;
1136 struct signal_struct *sig;
1137
1138 /*
1139 * The resource counters for the group leader are in its
1140 * own task_struct. Those for dead threads in the group
1141 * are in its signal_struct, as are those for the child
1142 * processes it has previously reaped. All these
1143 * accumulate in the parent's signal_struct c* fields.
1144 *
1145 * We don't bother to take a lock here to protect these
1146 * p->signal fields, because they are only touched by
1147 * __exit_signal, which runs with tasklist_lock
1148 * write-locked anyway, and so is excluded here. We do
1149 * need to protect the access to p->parent->signal fields,
1150 * as other threads in the parent group can be right
1151 * here reaping other children at the same time.
1152 */
1153 spin_lock_irq(&p->parent->sighand->siglock);
1154 psig = p->parent->signal;
1155 sig = p->signal;
1156 psig->cutime =
1157 cputime_add(psig->cutime,
1158 cputime_add(p->utime,
1159 cputime_add(sig->utime,
1160 sig->cutime)));
1161 psig->cstime =
1162 cputime_add(psig->cstime,
1163 cputime_add(p->stime,
1164 cputime_add(sig->stime,
1165 sig->cstime)));
1166 psig->cmin_flt +=
1167 p->min_flt + sig->min_flt + sig->cmin_flt;
1168 psig->cmaj_flt +=
1169 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1170 psig->cnvcsw +=
1171 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1172 psig->cnivcsw +=
1173 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1174 spin_unlock_irq(&p->parent->sighand->siglock);
1175 }
1176
1177 /*
1178 * Now we are sure this task is interesting, and no other
1179 * thread can reap it because we set its state to EXIT_DEAD.
1180 */
1181 read_unlock(&tasklist_lock);
1182
1183 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1184 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1185 ? p->signal->group_exit_code : p->exit_code;
1186 if (!retval && stat_addr)
1187 retval = put_user(status, stat_addr);
1188 if (!retval && infop)
1189 retval = put_user(SIGCHLD, &infop->si_signo);
1190 if (!retval && infop)
1191 retval = put_user(0, &infop->si_errno);
1192 if (!retval && infop) {
1193 int why;
1194
1195 if ((status & 0x7f) == 0) {
1196 why = CLD_EXITED;
1197 status >>= 8;
1198 } else {
1199 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1200 status &= 0x7f;
1201 }
1202 retval = put_user((short)why, &infop->si_code);
1203 if (!retval)
1204 retval = put_user(status, &infop->si_status);
1205 }
1206 if (!retval && infop)
1207 retval = put_user(p->pid, &infop->si_pid);
1208 if (!retval && infop)
1209 retval = put_user(p->uid, &infop->si_uid);
1210 if (retval) {
1211 // TODO: is this safe?
1212 p->exit_state = EXIT_ZOMBIE;
1213 return retval;
1214 }
1215 retval = p->pid;
1216 if (p->real_parent != p->parent) {
1217 write_lock_irq(&tasklist_lock);
1218 /* Double-check with lock held. */
1219 if (p->real_parent != p->parent) {
1220 __ptrace_unlink(p);
1221 // TODO: is this safe?
1222 p->exit_state = EXIT_ZOMBIE;
1223 /*
1224 * If this is not a detached task, notify the parent.
1225 * If it's still not detached after that, don't release
1226 * it now.
1227 */
1228 if (p->exit_signal != -1) {
1229 do_notify_parent(p, p->exit_signal);
1230 if (p->exit_signal != -1)
1231 p = NULL;
1232 }
1233 }
1234 write_unlock_irq(&tasklist_lock);
1235 }
1236 if (p != NULL)
1237 release_task(p);
1238 BUG_ON(!retval);
1239 return retval;
1240 }
1241
1242 /*
1243 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1244 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1245 * the lock and this task is uninteresting. If we return nonzero, we have
1246 * released the lock and the system call should return.
1247 */
1248 static int wait_task_stopped(task_t *p, int delayed_group_leader, int noreap,
1249 struct siginfo __user *infop,
1250 int __user *stat_addr, struct rusage __user *ru)
1251 {
1252 int retval, exit_code;
1253
1254 if (!p->exit_code)
1255 return 0;
1256 if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1257 p->signal && p->signal->group_stop_count > 0)
1258 /*
1259 * A group stop is in progress and this is the group leader.
1260 * We won't report until all threads have stopped.
1261 */
1262 return 0;
1263
1264 /*
1265 * Now we are pretty sure this task is interesting.
1266 * Make sure it doesn't get reaped out from under us while we
1267 * give up the lock and then examine it below. We don't want to
1268 * keep holding onto the tasklist_lock while we call getrusage and
1269 * possibly take page faults for user memory.
1270 */
1271 get_task_struct(p);
1272 read_unlock(&tasklist_lock);
1273
1274 if (unlikely(noreap)) {
1275 pid_t pid = p->pid;
1276 uid_t uid = p->uid;
1277 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1278
1279 exit_code = p->exit_code;
1280 if (unlikely(!exit_code) ||
1281 unlikely(p->state & TASK_TRACED))
1282 goto bail_ref;
1283 return wait_noreap_copyout(p, pid, uid,
1284 why, (exit_code << 8) | 0x7f,
1285 infop, ru);
1286 }
1287
1288 write_lock_irq(&tasklist_lock);
1289
1290 /*
1291 * This uses xchg to be atomic with the thread resuming and setting
1292 * it. It must also be done with the write lock held to prevent a
1293 * race with the EXIT_ZOMBIE case.
1294 */
1295 exit_code = xchg(&p->exit_code, 0);
1296 if (unlikely(p->exit_state)) {
1297 /*
1298 * The task resumed and then died. Let the next iteration
1299 * catch it in EXIT_ZOMBIE. Note that exit_code might
1300 * already be zero here if it resumed and did _exit(0).
1301 * The task itself is dead and won't touch exit_code again;
1302 * other processors in this function are locked out.
1303 */
1304 p->exit_code = exit_code;
1305 exit_code = 0;
1306 }
1307 if (unlikely(exit_code == 0)) {
1308 /*
1309 * Another thread in this function got to it first, or it
1310 * resumed, or it resumed and then died.
1311 */
1312 write_unlock_irq(&tasklist_lock);
1313 bail_ref:
1314 put_task_struct(p);
1315 /*
1316 * We are returning to the wait loop without having successfully
1317 * removed the process and having released the lock. We cannot
1318 * continue, since the "p" task pointer is potentially stale.
1319 *
1320 * Return -EAGAIN, and do_wait() will restart the loop from the
1321 * beginning. Do _not_ re-acquire the lock.
1322 */
1323 return -EAGAIN;
1324 }
1325
1326 /* move to end of parent's list to avoid starvation */
1327 remove_parent(p);
1328 add_parent(p);
1329
1330 write_unlock_irq(&tasklist_lock);
1331
1332 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1333 if (!retval && stat_addr)
1334 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1335 if (!retval && infop)
1336 retval = put_user(SIGCHLD, &infop->si_signo);
1337 if (!retval && infop)
1338 retval = put_user(0, &infop->si_errno);
1339 if (!retval && infop)
1340 retval = put_user((short)((p->ptrace & PT_PTRACED)
1341 ? CLD_TRAPPED : CLD_STOPPED),
1342 &infop->si_code);
1343 if (!retval && infop)
1344 retval = put_user(exit_code, &infop->si_status);
1345 if (!retval && infop)
1346 retval = put_user(p->pid, &infop->si_pid);
1347 if (!retval && infop)
1348 retval = put_user(p->uid, &infop->si_uid);
1349 if (!retval)
1350 retval = p->pid;
1351 put_task_struct(p);
1352
1353 BUG_ON(!retval);
1354 return retval;
1355 }
1356
1357 /*
1358 * Handle do_wait work for one task in a live, non-stopped state.
1359 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1360 * the lock and this task is uninteresting. If we return nonzero, we have
1361 * released the lock and the system call should return.
1362 */
1363 static int wait_task_continued(task_t *p, int noreap,
1364 struct siginfo __user *infop,
1365 int __user *stat_addr, struct rusage __user *ru)
1366 {
1367 int retval;
1368 pid_t pid;
1369 uid_t uid;
1370
1371 if (unlikely(!p->signal))
1372 return 0;
1373
1374 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1375 return 0;
1376
1377 spin_lock_irq(&p->sighand->siglock);
1378 /* Re-check with the lock held. */
1379 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1380 spin_unlock_irq(&p->sighand->siglock);
1381 return 0;
1382 }
1383 if (!noreap)
1384 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1385 spin_unlock_irq(&p->sighand->siglock);
1386
1387 pid = p->pid;
1388 uid = p->uid;
1389 get_task_struct(p);
1390 read_unlock(&tasklist_lock);
1391
1392 if (!infop) {
1393 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1394 put_task_struct(p);
1395 if (!retval && stat_addr)
1396 retval = put_user(0xffff, stat_addr);
1397 if (!retval)
1398 retval = p->pid;
1399 } else {
1400 retval = wait_noreap_copyout(p, pid, uid,
1401 CLD_CONTINUED, SIGCONT,
1402 infop, ru);
1403 BUG_ON(retval == 0);
1404 }
1405
1406 return retval;
1407 }
1408
1409
1410 static inline int my_ptrace_child(struct task_struct *p)
1411 {
1412 if (!(p->ptrace & PT_PTRACED))
1413 return 0;
1414 if (!(p->ptrace & PT_ATTACHED))
1415 return 1;
1416 /*
1417 * This child was PTRACE_ATTACH'd. We should be seeing it only if
1418 * we are the attacher. If we are the real parent, this is a race
1419 * inside ptrace_attach. It is waiting for the tasklist_lock,
1420 * which we have to switch the parent links, but has already set
1421 * the flags in p->ptrace.
1422 */
1423 return (p->parent != p->real_parent);
1424 }
1425
1426 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1427 int __user *stat_addr, struct rusage __user *ru)
1428 {
1429 DECLARE_WAITQUEUE(wait, current);
1430 struct task_struct *tsk;
1431 int flag, retval;
1432
1433 add_wait_queue(&current->signal->wait_chldexit,&wait);
1434 repeat:
1435 /*
1436 * We will set this flag if we see any child that might later
1437 * match our criteria, even if we are not able to reap it yet.
1438 */
1439 flag = 0;
1440 current->state = TASK_INTERRUPTIBLE;
1441 read_lock(&tasklist_lock);
1442 tsk = current;
1443 do {
1444 struct task_struct *p;
1445 struct list_head *_p;
1446 int ret;
1447
1448 list_for_each(_p,&tsk->children) {
1449 p = list_entry(_p,struct task_struct,sibling);
1450
1451 ret = eligible_child(pid, options, p);
1452 if (!ret)
1453 continue;
1454
1455 switch (p->state) {
1456 case TASK_TRACED:
1457 /*
1458 * When we hit the race with PTRACE_ATTACH,
1459 * we will not report this child. But the
1460 * race means it has not yet been moved to
1461 * our ptrace_children list, so we need to
1462 * set the flag here to avoid a spurious ECHILD
1463 * when the race happens with the only child.
1464 */
1465 flag = 1;
1466 if (!my_ptrace_child(p))
1467 continue;
1468 /*FALLTHROUGH*/
1469 case TASK_STOPPED:
1470 /*
1471 * It's stopped now, so it might later
1472 * continue, exit, or stop again.
1473 */
1474 flag = 1;
1475 if (!(options & WUNTRACED) &&
1476 !my_ptrace_child(p))
1477 continue;
1478 retval = wait_task_stopped(p, ret == 2,
1479 (options & WNOWAIT),
1480 infop,
1481 stat_addr, ru);
1482 if (retval == -EAGAIN)
1483 goto repeat;
1484 if (retval != 0) /* He released the lock. */
1485 goto end;
1486 break;
1487 default:
1488 // case EXIT_DEAD:
1489 if (p->exit_state == EXIT_DEAD)
1490 continue;
1491 // case EXIT_ZOMBIE:
1492 if (p->exit_state == EXIT_ZOMBIE) {
1493 /*
1494 * Eligible but we cannot release
1495 * it yet:
1496 */
1497 if (ret == 2)
1498 goto check_continued;
1499 if (!likely(options & WEXITED))
1500 continue;
1501 retval = wait_task_zombie(
1502 p, (options & WNOWAIT),
1503 infop, stat_addr, ru);
1504 /* He released the lock. */
1505 if (retval != 0)
1506 goto end;
1507 break;
1508 }
1509 check_continued:
1510 /*
1511 * It's running now, so it might later
1512 * exit, stop, or stop and then continue.
1513 */
1514 flag = 1;
1515 if (!unlikely(options & WCONTINUED))
1516 continue;
1517 retval = wait_task_continued(
1518 p, (options & WNOWAIT),
1519 infop, stat_addr, ru);
1520 if (retval != 0) /* He released the lock. */
1521 goto end;
1522 break;
1523 }
1524 }
1525 if (!flag) {
1526 list_for_each(_p, &tsk->ptrace_children) {
1527 p = list_entry(_p, struct task_struct,
1528 ptrace_list);
1529 if (!eligible_child(pid, options, p))
1530 continue;
1531 flag = 1;
1532 break;
1533 }
1534 }
1535 if (options & __WNOTHREAD)
1536 break;
1537 tsk = next_thread(tsk);
1538 BUG_ON(tsk->signal != current->signal);
1539 } while (tsk != current);
1540
1541 read_unlock(&tasklist_lock);
1542 if (flag) {
1543 retval = 0;
1544 if (options & WNOHANG)
1545 goto end;
1546 retval = -ERESTARTSYS;
1547 if (signal_pending(current))
1548 goto end;
1549 schedule();
1550 goto repeat;
1551 }
1552 retval = -ECHILD;
1553 end:
1554 current->state = TASK_RUNNING;
1555 remove_wait_queue(&current->signal->wait_chldexit,&wait);
1556 if (infop) {
1557 if (retval > 0)
1558 retval = 0;
1559 else {
1560 /*
1561 * For a WNOHANG return, clear out all the fields
1562 * we would set so the user can easily tell the
1563 * difference.
1564 */
1565 if (!retval)
1566 retval = put_user(0, &infop->si_signo);
1567 if (!retval)
1568 retval = put_user(0, &infop->si_errno);
1569 if (!retval)
1570 retval = put_user(0, &infop->si_code);
1571 if (!retval)
1572 retval = put_user(0, &infop->si_pid);
1573 if (!retval)
1574 retval = put_user(0, &infop->si_uid);
1575 if (!retval)
1576 retval = put_user(0, &infop->si_status);
1577 }
1578 }
1579 return retval;
1580 }
1581
1582 asmlinkage long sys_waitid(int which, pid_t pid,
1583 struct siginfo __user *infop, int options,
1584 struct rusage __user *ru)
1585 {
1586 long ret;
1587
1588 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1589 return -EINVAL;
1590 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1591 return -EINVAL;
1592
1593 switch (which) {
1594 case P_ALL:
1595 pid = -1;
1596 break;
1597 case P_PID:
1598 if (pid <= 0)
1599 return -EINVAL;
1600 break;
1601 case P_PGID:
1602 if (pid <= 0)
1603 return -EINVAL;
1604 pid = -pid;
1605 break;
1606 default:
1607 return -EINVAL;
1608 }
1609
1610 ret = do_wait(pid, options, infop, NULL, ru);
1611
1612 /* avoid REGPARM breakage on x86: */
1613 prevent_tail_call(ret);
1614 return ret;
1615 }
1616
1617 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1618 int options, struct rusage __user *ru)
1619 {
1620 long ret;
1621
1622 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1623 __WNOTHREAD|__WCLONE|__WALL))
1624 return -EINVAL;
1625 ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1626
1627 /* avoid REGPARM breakage on x86: */
1628 prevent_tail_call(ret);
1629 return ret;
1630 }
1631
1632 #ifdef __ARCH_WANT_SYS_WAITPID
1633
1634 /*
1635 * sys_waitpid() remains for compatibility. waitpid() should be
1636 * implemented by calling sys_wait4() from libc.a.
1637 */
1638 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1639 {
1640 return sys_wait4(pid, stat_addr, options, NULL);
1641 }
1642
1643 #endif