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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/taskstats_kern.h>
29 #include <linux/delayacct.h>
30 #include <linux/cpuset.h>
31 #include <linux/syscalls.h>
32 #include <linux/signal.h>
33 #include <linux/posix-timers.h>
34 #include <linux/cn_proc.h>
35 #include <linux/mutex.h>
36 #include <linux/futex.h>
37 #include <linux/compat.h>
38 #include <linux/pipe_fs_i.h>
39 #include <linux/audit.h> /* for audit_free() */
40 #include <linux/resource.h>
41
42 #include <asm/uaccess.h>
43 #include <asm/unistd.h>
44 #include <asm/pgtable.h>
45 #include <asm/mmu_context.h>
46
47 extern void sem_exit (void);
48 extern struct task_struct *child_reaper;
49
50 static void exit_mm(struct task_struct * tsk);
51
52 static void __unhash_process(struct task_struct *p)
53 {
54 nr_threads--;
55 detach_pid(p, PIDTYPE_PID);
56 if (thread_group_leader(p)) {
57 detach_pid(p, PIDTYPE_PGID);
58 detach_pid(p, PIDTYPE_SID);
59
60 list_del_rcu(&p->tasks);
61 __get_cpu_var(process_counts)--;
62 }
63 list_del_rcu(&p->thread_group);
64 remove_parent(p);
65 }
66
67 /*
68 * This function expects the tasklist_lock write-locked.
69 */
70 static void __exit_signal(struct task_struct *tsk)
71 {
72 struct signal_struct *sig = tsk->signal;
73 struct sighand_struct *sighand;
74
75 BUG_ON(!sig);
76 BUG_ON(!atomic_read(&sig->count));
77
78 rcu_read_lock();
79 sighand = rcu_dereference(tsk->sighand);
80 spin_lock(&sighand->siglock);
81
82 posix_cpu_timers_exit(tsk);
83 if (atomic_dec_and_test(&sig->count))
84 posix_cpu_timers_exit_group(tsk);
85 else {
86 /*
87 * If there is any task waiting for the group exit
88 * then notify it:
89 */
90 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
91 wake_up_process(sig->group_exit_task);
92 sig->group_exit_task = NULL;
93 }
94 if (tsk == sig->curr_target)
95 sig->curr_target = next_thread(tsk);
96 /*
97 * Accumulate here the counters for all threads but the
98 * group leader as they die, so they can be added into
99 * the process-wide totals when those are taken.
100 * The group leader stays around as a zombie as long
101 * as there are other threads. When it gets reaped,
102 * the exit.c code will add its counts into these totals.
103 * We won't ever get here for the group leader, since it
104 * will have been the last reference on the signal_struct.
105 */
106 sig->utime = cputime_add(sig->utime, tsk->utime);
107 sig->stime = cputime_add(sig->stime, tsk->stime);
108 sig->min_flt += tsk->min_flt;
109 sig->maj_flt += tsk->maj_flt;
110 sig->nvcsw += tsk->nvcsw;
111 sig->nivcsw += tsk->nivcsw;
112 sig->sched_time += tsk->sched_time;
113 sig = NULL; /* Marker for below. */
114 }
115
116 __unhash_process(tsk);
117
118 tsk->signal = NULL;
119 tsk->sighand = NULL;
120 spin_unlock(&sighand->siglock);
121 rcu_read_unlock();
122
123 __cleanup_sighand(sighand);
124 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
125 flush_sigqueue(&tsk->pending);
126 if (sig) {
127 flush_sigqueue(&sig->shared_pending);
128 __cleanup_signal(sig);
129 }
130 }
131
132 static void delayed_put_task_struct(struct rcu_head *rhp)
133 {
134 put_task_struct(container_of(rhp, struct task_struct, rcu));
135 }
136
137 void release_task(struct task_struct * p)
138 {
139 struct task_struct *leader;
140 int zap_leader;
141 repeat:
142 atomic_dec(&p->user->processes);
143 write_lock_irq(&tasklist_lock);
144 ptrace_unlink(p);
145 BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
146 __exit_signal(p);
147
148 /*
149 * If we are the last non-leader member of the thread
150 * group, and the leader is zombie, then notify the
151 * group leader's parent process. (if it wants notification.)
152 */
153 zap_leader = 0;
154 leader = p->group_leader;
155 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
156 BUG_ON(leader->exit_signal == -1);
157 do_notify_parent(leader, leader->exit_signal);
158 /*
159 * If we were the last child thread and the leader has
160 * exited already, and the leader's parent ignores SIGCHLD,
161 * then we are the one who should release the leader.
162 *
163 * do_notify_parent() will have marked it self-reaping in
164 * that case.
165 */
166 zap_leader = (leader->exit_signal == -1);
167 }
168
169 sched_exit(p);
170 write_unlock_irq(&tasklist_lock);
171 proc_flush_task(p);
172 release_thread(p);
173 call_rcu(&p->rcu, delayed_put_task_struct);
174
175 p = leader;
176 if (unlikely(zap_leader))
177 goto repeat;
178 }
179
180 /*
181 * This checks not only the pgrp, but falls back on the pid if no
182 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
183 * without this...
184 */
185 int session_of_pgrp(int pgrp)
186 {
187 struct task_struct *p;
188 int sid = -1;
189
190 read_lock(&tasklist_lock);
191 do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
192 if (p->signal->session > 0) {
193 sid = p->signal->session;
194 goto out;
195 }
196 } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
197 p = find_task_by_pid(pgrp);
198 if (p)
199 sid = p->signal->session;
200 out:
201 read_unlock(&tasklist_lock);
202
203 return sid;
204 }
205
206 /*
207 * Determine if a process group is "orphaned", according to the POSIX
208 * definition in 2.2.2.52. Orphaned process groups are not to be affected
209 * by terminal-generated stop signals. Newly orphaned process groups are
210 * to receive a SIGHUP and a SIGCONT.
211 *
212 * "I ask you, have you ever known what it is to be an orphan?"
213 */
214 static int will_become_orphaned_pgrp(int pgrp, struct task_struct *ignored_task)
215 {
216 struct task_struct *p;
217 int ret = 1;
218
219 do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
220 if (p == ignored_task
221 || p->exit_state
222 || is_init(p->real_parent))
223 continue;
224 if (process_group(p->real_parent) != pgrp
225 && p->real_parent->signal->session == p->signal->session) {
226 ret = 0;
227 break;
228 }
229 } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
230 return ret; /* (sighing) "Often!" */
231 }
232
233 int is_orphaned_pgrp(int pgrp)
234 {
235 int retval;
236
237 read_lock(&tasklist_lock);
238 retval = will_become_orphaned_pgrp(pgrp, NULL);
239 read_unlock(&tasklist_lock);
240
241 return retval;
242 }
243
244 static int has_stopped_jobs(int pgrp)
245 {
246 int retval = 0;
247 struct task_struct *p;
248
249 do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
250 if (p->state != TASK_STOPPED)
251 continue;
252 retval = 1;
253 break;
254 } while_each_task_pid(pgrp, PIDTYPE_PGID, p);
255 return retval;
256 }
257
258 /**
259 * reparent_to_init - Reparent the calling kernel thread to the init task.
260 *
261 * If a kernel thread is launched as a result of a system call, or if
262 * it ever exits, it should generally reparent itself to init so that
263 * it is correctly cleaned up on exit.
264 *
265 * The various task state such as scheduling policy and priority may have
266 * been inherited from a user process, so we reset them to sane values here.
267 *
268 * NOTE that reparent_to_init() gives the caller full capabilities.
269 */
270 static void reparent_to_init(void)
271 {
272 write_lock_irq(&tasklist_lock);
273
274 ptrace_unlink(current);
275 /* Reparent to init */
276 remove_parent(current);
277 current->parent = child_reaper;
278 current->real_parent = child_reaper;
279 add_parent(current);
280
281 /* Set the exit signal to SIGCHLD so we signal init on exit */
282 current->exit_signal = SIGCHLD;
283
284 if (!has_rt_policy(current) && (task_nice(current) < 0))
285 set_user_nice(current, 0);
286 /* cpus_allowed? */
287 /* rt_priority? */
288 /* signals? */
289 security_task_reparent_to_init(current);
290 memcpy(current->signal->rlim, init_task.signal->rlim,
291 sizeof(current->signal->rlim));
292 atomic_inc(&(INIT_USER->__count));
293 write_unlock_irq(&tasklist_lock);
294 switch_uid(INIT_USER);
295 }
296
297 void __set_special_pids(pid_t session, pid_t pgrp)
298 {
299 struct task_struct *curr = current->group_leader;
300
301 if (curr->signal->session != session) {
302 detach_pid(curr, PIDTYPE_SID);
303 curr->signal->session = session;
304 attach_pid(curr, PIDTYPE_SID, session);
305 }
306 if (process_group(curr) != pgrp) {
307 detach_pid(curr, PIDTYPE_PGID);
308 curr->signal->pgrp = pgrp;
309 attach_pid(curr, PIDTYPE_PGID, pgrp);
310 }
311 }
312
313 void set_special_pids(pid_t session, pid_t pgrp)
314 {
315 write_lock_irq(&tasklist_lock);
316 __set_special_pids(session, pgrp);
317 write_unlock_irq(&tasklist_lock);
318 }
319
320 /*
321 * Let kernel threads use this to say that they
322 * allow a certain signal (since daemonize() will
323 * have disabled all of them by default).
324 */
325 int allow_signal(int sig)
326 {
327 if (!valid_signal(sig) || sig < 1)
328 return -EINVAL;
329
330 spin_lock_irq(&current->sighand->siglock);
331 sigdelset(&current->blocked, sig);
332 if (!current->mm) {
333 /* Kernel threads handle their own signals.
334 Let the signal code know it'll be handled, so
335 that they don't get converted to SIGKILL or
336 just silently dropped */
337 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
338 }
339 recalc_sigpending();
340 spin_unlock_irq(&current->sighand->siglock);
341 return 0;
342 }
343
344 EXPORT_SYMBOL(allow_signal);
345
346 int disallow_signal(int sig)
347 {
348 if (!valid_signal(sig) || sig < 1)
349 return -EINVAL;
350
351 spin_lock_irq(&current->sighand->siglock);
352 sigaddset(&current->blocked, sig);
353 recalc_sigpending();
354 spin_unlock_irq(&current->sighand->siglock);
355 return 0;
356 }
357
358 EXPORT_SYMBOL(disallow_signal);
359
360 /*
361 * Put all the gunge required to become a kernel thread without
362 * attached user resources in one place where it belongs.
363 */
364
365 void daemonize(const char *name, ...)
366 {
367 va_list args;
368 struct fs_struct *fs;
369 sigset_t blocked;
370
371 va_start(args, name);
372 vsnprintf(current->comm, sizeof(current->comm), name, args);
373 va_end(args);
374
375 /*
376 * If we were started as result of loading a module, close all of the
377 * user space pages. We don't need them, and if we didn't close them
378 * they would be locked into memory.
379 */
380 exit_mm(current);
381
382 set_special_pids(1, 1);
383 mutex_lock(&tty_mutex);
384 current->signal->tty = NULL;
385 mutex_unlock(&tty_mutex);
386
387 /* Block and flush all signals */
388 sigfillset(&blocked);
389 sigprocmask(SIG_BLOCK, &blocked, NULL);
390 flush_signals(current);
391
392 /* Become as one with the init task */
393
394 exit_fs(current); /* current->fs->count--; */
395 fs = init_task.fs;
396 current->fs = fs;
397 atomic_inc(&fs->count);
398 exit_namespace(current);
399 current->namespace = init_task.namespace;
400 get_namespace(current->namespace);
401 exit_files(current);
402 current->files = init_task.files;
403 atomic_inc(&current->files->count);
404
405 reparent_to_init();
406 }
407
408 EXPORT_SYMBOL(daemonize);
409
410 static void close_files(struct files_struct * files)
411 {
412 int i, j;
413 struct fdtable *fdt;
414
415 j = 0;
416
417 /*
418 * It is safe to dereference the fd table without RCU or
419 * ->file_lock because this is the last reference to the
420 * files structure.
421 */
422 fdt = files_fdtable(files);
423 for (;;) {
424 unsigned long set;
425 i = j * __NFDBITS;
426 if (i >= fdt->max_fdset || i >= fdt->max_fds)
427 break;
428 set = fdt->open_fds->fds_bits[j++];
429 while (set) {
430 if (set & 1) {
431 struct file * file = xchg(&fdt->fd[i], NULL);
432 if (file)
433 filp_close(file, files);
434 }
435 i++;
436 set >>= 1;
437 }
438 }
439 }
440
441 struct files_struct *get_files_struct(struct task_struct *task)
442 {
443 struct files_struct *files;
444
445 task_lock(task);
446 files = task->files;
447 if (files)
448 atomic_inc(&files->count);
449 task_unlock(task);
450
451 return files;
452 }
453
454 void fastcall put_files_struct(struct files_struct *files)
455 {
456 struct fdtable *fdt;
457
458 if (atomic_dec_and_test(&files->count)) {
459 close_files(files);
460 /*
461 * Free the fd and fdset arrays if we expanded them.
462 * If the fdtable was embedded, pass files for freeing
463 * at the end of the RCU grace period. Otherwise,
464 * you can free files immediately.
465 */
466 fdt = files_fdtable(files);
467 if (fdt == &files->fdtab)
468 fdt->free_files = files;
469 else
470 kmem_cache_free(files_cachep, files);
471 free_fdtable(fdt);
472 }
473 }
474
475 EXPORT_SYMBOL(put_files_struct);
476
477 void reset_files_struct(struct task_struct *tsk, struct files_struct *files)
478 {
479 struct files_struct *old;
480
481 old = tsk->files;
482 task_lock(tsk);
483 tsk->files = files;
484 task_unlock(tsk);
485 put_files_struct(old);
486 }
487 EXPORT_SYMBOL(reset_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
587 choose_new_parent(struct task_struct *p, struct task_struct *reaper)
588 {
589 /*
590 * Make sure we're not reparenting to ourselves and that
591 * the parent is not a zombie.
592 */
593 BUG_ON(p == reaper || reaper->exit_state);
594 p->real_parent = reaper;
595 }
596
597 static void
598 reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
599 {
600 /* We don't want people slaying init. */
601 if (p->exit_signal != -1)
602 p->exit_signal = SIGCHLD;
603
604 if (p->pdeath_signal)
605 /* We already hold the tasklist_lock here. */
606 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
607
608 /* Move the child from its dying parent to the new one. */
609 if (unlikely(traced)) {
610 /* Preserve ptrace links if someone else is tracing this child. */
611 list_del_init(&p->ptrace_list);
612 if (p->parent != p->real_parent)
613 list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
614 } else {
615 /* If this child is being traced, then we're the one tracing it
616 * anyway, so let go of it.
617 */
618 p->ptrace = 0;
619 remove_parent(p);
620 p->parent = p->real_parent;
621 add_parent(p);
622
623 /* If we'd notified the old parent about this child's death,
624 * also notify the new parent.
625 */
626 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
627 thread_group_empty(p))
628 do_notify_parent(p, p->exit_signal);
629 else if (p->state == TASK_TRACED) {
630 /*
631 * If it was at a trace stop, turn it into
632 * a normal stop since it's no longer being
633 * traced.
634 */
635 ptrace_untrace(p);
636 }
637 }
638
639 /*
640 * process group orphan check
641 * Case ii: Our child is in a different pgrp
642 * than we are, and it was the only connection
643 * outside, so the child pgrp is now orphaned.
644 */
645 if ((process_group(p) != process_group(father)) &&
646 (p->signal->session == father->signal->session)) {
647 int pgrp = process_group(p);
648
649 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
650 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
651 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);
652 }
653 }
654 }
655
656 /*
657 * When we die, we re-parent all our children.
658 * Try to give them to another thread in our thread
659 * group, and if no such member exists, give it to
660 * the global child reaper process (ie "init")
661 */
662 static void
663 forget_original_parent(struct task_struct *father, struct list_head *to_release)
664 {
665 struct task_struct *p, *reaper = father;
666 struct list_head *_p, *_n;
667
668 do {
669 reaper = next_thread(reaper);
670 if (reaper == father) {
671 reaper = child_reaper;
672 break;
673 }
674 } while (reaper->exit_state);
675
676 /*
677 * There are only two places where our children can be:
678 *
679 * - in our child list
680 * - in our ptraced child list
681 *
682 * Search them and reparent children.
683 */
684 list_for_each_safe(_p, _n, &father->children) {
685 int ptrace;
686 p = list_entry(_p, struct task_struct, sibling);
687
688 ptrace = p->ptrace;
689
690 /* if father isn't the real parent, then ptrace must be enabled */
691 BUG_ON(father != p->real_parent && !ptrace);
692
693 if (father == p->real_parent) {
694 /* reparent with a reaper, real father it's us */
695 choose_new_parent(p, reaper);
696 reparent_thread(p, father, 0);
697 } else {
698 /* reparent ptraced task to its real parent */
699 __ptrace_unlink (p);
700 if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
701 thread_group_empty(p))
702 do_notify_parent(p, p->exit_signal);
703 }
704
705 /*
706 * if the ptraced child is a zombie with exit_signal == -1
707 * we must collect it before we exit, or it will remain
708 * zombie forever since we prevented it from self-reap itself
709 * while it was being traced by us, to be able to see it in wait4.
710 */
711 if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
712 list_add(&p->ptrace_list, to_release);
713 }
714 list_for_each_safe(_p, _n, &father->ptrace_children) {
715 p = list_entry(_p, struct task_struct, ptrace_list);
716 choose_new_parent(p, reaper);
717 reparent_thread(p, father, 1);
718 }
719 }
720
721 /*
722 * Send signals to all our closest relatives so that they know
723 * to properly mourn us..
724 */
725 static void exit_notify(struct task_struct *tsk)
726 {
727 int state;
728 struct task_struct *t;
729 struct list_head ptrace_dead, *_p, *_n;
730
731 if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
732 && !thread_group_empty(tsk)) {
733 /*
734 * This occurs when there was a race between our exit
735 * syscall and a group signal choosing us as the one to
736 * wake up. It could be that we are the only thread
737 * alerted to check for pending signals, but another thread
738 * should be woken now to take the signal since we will not.
739 * Now we'll wake all the threads in the group just to make
740 * sure someone gets all the pending signals.
741 */
742 read_lock(&tasklist_lock);
743 spin_lock_irq(&tsk->sighand->siglock);
744 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
745 if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
746 recalc_sigpending_tsk(t);
747 if (signal_pending(t))
748 signal_wake_up(t, 0);
749 }
750 spin_unlock_irq(&tsk->sighand->siglock);
751 read_unlock(&tasklist_lock);
752 }
753
754 write_lock_irq(&tasklist_lock);
755
756 /*
757 * This does two things:
758 *
759 * A. Make init inherit all the child processes
760 * B. Check to see if any process groups have become orphaned
761 * as a result of our exiting, and if they have any stopped
762 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
763 */
764
765 INIT_LIST_HEAD(&ptrace_dead);
766 forget_original_parent(tsk, &ptrace_dead);
767 BUG_ON(!list_empty(&tsk->children));
768 BUG_ON(!list_empty(&tsk->ptrace_children));
769
770 /*
771 * Check to see if any process groups have become orphaned
772 * as a result of our exiting, and if they have any stopped
773 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
774 *
775 * Case i: Our father is in a different pgrp than we are
776 * and we were the only connection outside, so our pgrp
777 * is about to become orphaned.
778 */
779
780 t = tsk->real_parent;
781
782 if ((process_group(t) != process_group(tsk)) &&
783 (t->signal->session == tsk->signal->session) &&
784 will_become_orphaned_pgrp(process_group(tsk), tsk) &&
785 has_stopped_jobs(process_group(tsk))) {
786 __kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
787 __kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));
788 }
789
790 /* Let father know we died
791 *
792 * Thread signals are configurable, but you aren't going to use
793 * that to send signals to arbitary processes.
794 * That stops right now.
795 *
796 * If the parent exec id doesn't match the exec id we saved
797 * when we started then we know the parent has changed security
798 * domain.
799 *
800 * If our self_exec id doesn't match our parent_exec_id then
801 * we have changed execution domain as these two values started
802 * the same after a fork.
803 *
804 */
805
806 if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
807 ( tsk->parent_exec_id != t->self_exec_id ||
808 tsk->self_exec_id != tsk->parent_exec_id)
809 && !capable(CAP_KILL))
810 tsk->exit_signal = SIGCHLD;
811
812
813 /* If something other than our normal parent is ptracing us, then
814 * send it a SIGCHLD instead of honoring exit_signal. exit_signal
815 * only has special meaning to our real parent.
816 */
817 if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
818 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
819 do_notify_parent(tsk, signal);
820 } else if (tsk->ptrace) {
821 do_notify_parent(tsk, SIGCHLD);
822 }
823
824 state = EXIT_ZOMBIE;
825 if (tsk->exit_signal == -1 &&
826 (likely(tsk->ptrace == 0) ||
827 unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
828 state = EXIT_DEAD;
829 tsk->exit_state = state;
830
831 write_unlock_irq(&tasklist_lock);
832
833 list_for_each_safe(_p, _n, &ptrace_dead) {
834 list_del_init(_p);
835 t = list_entry(_p, struct task_struct, ptrace_list);
836 release_task(t);
837 }
838
839 /* If the process is dead, release it - nobody will wait for it */
840 if (state == EXIT_DEAD)
841 release_task(tsk);
842 }
843
844 fastcall NORET_TYPE void do_exit(long code)
845 {
846 struct task_struct *tsk = current;
847 struct taskstats *tidstats;
848 int group_dead;
849 unsigned int mycpu;
850
851 profile_task_exit(tsk);
852
853 WARN_ON(atomic_read(&tsk->fs_excl));
854
855 if (unlikely(in_interrupt()))
856 panic("Aiee, killing interrupt handler!");
857 if (unlikely(!tsk->pid))
858 panic("Attempted to kill the idle task!");
859 if (unlikely(tsk == child_reaper))
860 panic("Attempted to kill init!");
861
862 if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
863 current->ptrace_message = code;
864 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
865 }
866
867 /*
868 * We're taking recursive faults here in do_exit. Safest is to just
869 * leave this task alone and wait for reboot.
870 */
871 if (unlikely(tsk->flags & PF_EXITING)) {
872 printk(KERN_ALERT
873 "Fixing recursive fault but reboot is needed!\n");
874 if (tsk->io_context)
875 exit_io_context();
876 set_current_state(TASK_UNINTERRUPTIBLE);
877 schedule();
878 }
879
880 tsk->flags |= PF_EXITING;
881
882 if (unlikely(in_atomic()))
883 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
884 current->comm, current->pid,
885 preempt_count());
886
887 taskstats_exit_alloc(&tidstats, &mycpu);
888
889 acct_update_integrals(tsk);
890 if (tsk->mm) {
891 update_hiwater_rss(tsk->mm);
892 update_hiwater_vm(tsk->mm);
893 }
894 group_dead = atomic_dec_and_test(&tsk->signal->live);
895 if (group_dead) {
896 hrtimer_cancel(&tsk->signal->real_timer);
897 exit_itimers(tsk->signal);
898 }
899 acct_collect(code, group_dead);
900 if (unlikely(tsk->robust_list))
901 exit_robust_list(tsk);
902 #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
903 if (unlikely(tsk->compat_robust_list))
904 compat_exit_robust_list(tsk);
905 #endif
906 if (unlikely(tsk->audit_context))
907 audit_free(tsk);
908 taskstats_exit_send(tsk, tidstats, group_dead, mycpu);
909 taskstats_exit_free(tidstats);
910
911 exit_mm(tsk);
912
913 if (group_dead)
914 acct_process();
915 exit_sem(tsk);
916 __exit_files(tsk);
917 __exit_fs(tsk);
918 exit_namespace(tsk);
919 exit_thread();
920 cpuset_exit(tsk);
921 exit_keys(tsk);
922
923 if (group_dead && tsk->signal->leader)
924 disassociate_ctty(1);
925
926 module_put(task_thread_info(tsk)->exec_domain->module);
927 if (tsk->binfmt)
928 module_put(tsk->binfmt->module);
929
930 tsk->exit_code = code;
931 proc_exit_connector(tsk);
932 exit_notify(tsk);
933 #ifdef CONFIG_NUMA
934 mpol_free(tsk->mempolicy);
935 tsk->mempolicy = NULL;
936 #endif
937 /*
938 * This must happen late, after the PID is not
939 * hashed anymore:
940 */
941 if (unlikely(!list_empty(&tsk->pi_state_list)))
942 exit_pi_state_list(tsk);
943 if (unlikely(current->pi_state_cache))
944 kfree(current->pi_state_cache);
945 /*
946 * Make sure we are holding no locks:
947 */
948 debug_check_no_locks_held(tsk);
949
950 if (tsk->io_context)
951 exit_io_context();
952
953 if (tsk->splice_pipe)
954 __free_pipe_info(tsk->splice_pipe);
955
956 preempt_disable();
957 /* causes final put_task_struct in finish_task_switch(). */
958 tsk->state = TASK_DEAD;
959
960 schedule();
961 BUG();
962 /* Avoid "noreturn function does return". */
963 for (;;)
964 cpu_relax(); /* For when BUG is null */
965 }
966
967 EXPORT_SYMBOL_GPL(do_exit);
968
969 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
970 {
971 if (comp)
972 complete(comp);
973
974 do_exit(code);
975 }
976
977 EXPORT_SYMBOL(complete_and_exit);
978
979 asmlinkage long sys_exit(int error_code)
980 {
981 do_exit((error_code&0xff)<<8);
982 }
983
984 /*
985 * Take down every thread in the group. This is called by fatal signals
986 * as well as by sys_exit_group (below).
987 */
988 NORET_TYPE void
989 do_group_exit(int exit_code)
990 {
991 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
992
993 if (current->signal->flags & SIGNAL_GROUP_EXIT)
994 exit_code = current->signal->group_exit_code;
995 else if (!thread_group_empty(current)) {
996 struct signal_struct *const sig = current->signal;
997 struct sighand_struct *const sighand = current->sighand;
998 spin_lock_irq(&sighand->siglock);
999 if (sig->flags & SIGNAL_GROUP_EXIT)
1000 /* Another thread got here before we took the lock. */
1001 exit_code = sig->group_exit_code;
1002 else {
1003 sig->group_exit_code = exit_code;
1004 zap_other_threads(current);
1005 }
1006 spin_unlock_irq(&sighand->siglock);
1007 }
1008
1009 do_exit(exit_code);
1010 /* NOTREACHED */
1011 }
1012
1013 /*
1014 * this kills every thread in the thread group. Note that any externally
1015 * wait4()-ing process will get the correct exit code - even if this
1016 * thread is not the thread group leader.
1017 */
1018 asmlinkage void sys_exit_group(int error_code)
1019 {
1020 do_group_exit((error_code & 0xff) << 8);
1021 }
1022
1023 static int eligible_child(pid_t pid, int options, struct task_struct *p)
1024 {
1025 if (pid > 0) {
1026 if (p->pid != pid)
1027 return 0;
1028 } else if (!pid) {
1029 if (process_group(p) != process_group(current))
1030 return 0;
1031 } else if (pid != -1) {
1032 if (process_group(p) != -pid)
1033 return 0;
1034 }
1035
1036 /*
1037 * Do not consider detached threads that are
1038 * not ptraced:
1039 */
1040 if (p->exit_signal == -1 && !p->ptrace)
1041 return 0;
1042
1043 /* Wait for all children (clone and not) if __WALL is set;
1044 * otherwise, wait for clone children *only* if __WCLONE is
1045 * set; otherwise, wait for non-clone children *only*. (Note:
1046 * A "clone" child here is one that reports to its parent
1047 * using a signal other than SIGCHLD.) */
1048 if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1049 && !(options & __WALL))
1050 return 0;
1051 /*
1052 * Do not consider thread group leaders that are
1053 * in a non-empty thread group:
1054 */
1055 if (delay_group_leader(p))
1056 return 2;
1057
1058 if (security_task_wait(p))
1059 return 0;
1060
1061 return 1;
1062 }
1063
1064 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1065 int why, int status,
1066 struct siginfo __user *infop,
1067 struct rusage __user *rusagep)
1068 {
1069 int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1070
1071 put_task_struct(p);
1072 if (!retval)
1073 retval = put_user(SIGCHLD, &infop->si_signo);
1074 if (!retval)
1075 retval = put_user(0, &infop->si_errno);
1076 if (!retval)
1077 retval = put_user((short)why, &infop->si_code);
1078 if (!retval)
1079 retval = put_user(pid, &infop->si_pid);
1080 if (!retval)
1081 retval = put_user(uid, &infop->si_uid);
1082 if (!retval)
1083 retval = put_user(status, &infop->si_status);
1084 if (!retval)
1085 retval = pid;
1086 return retval;
1087 }
1088
1089 /*
1090 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1091 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1092 * the lock and this task is uninteresting. If we return nonzero, we have
1093 * released the lock and the system call should return.
1094 */
1095 static int wait_task_zombie(struct task_struct *p, int noreap,
1096 struct siginfo __user *infop,
1097 int __user *stat_addr, struct rusage __user *ru)
1098 {
1099 unsigned long state;
1100 int retval;
1101 int status;
1102
1103 if (unlikely(noreap)) {
1104 pid_t pid = p->pid;
1105 uid_t uid = p->uid;
1106 int exit_code = p->exit_code;
1107 int why, status;
1108
1109 if (unlikely(p->exit_state != EXIT_ZOMBIE))
1110 return 0;
1111 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
1112 return 0;
1113 get_task_struct(p);
1114 read_unlock(&tasklist_lock);
1115 if ((exit_code & 0x7f) == 0) {
1116 why = CLD_EXITED;
1117 status = exit_code >> 8;
1118 } else {
1119 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1120 status = exit_code & 0x7f;
1121 }
1122 return wait_noreap_copyout(p, pid, uid, why,
1123 status, infop, ru);
1124 }
1125
1126 /*
1127 * Try to move the task's state to DEAD
1128 * only one thread is allowed to do this:
1129 */
1130 state = xchg(&p->exit_state, EXIT_DEAD);
1131 if (state != EXIT_ZOMBIE) {
1132 BUG_ON(state != EXIT_DEAD);
1133 return 0;
1134 }
1135 if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
1136 /*
1137 * This can only happen in a race with a ptraced thread
1138 * dying on another processor.
1139 */
1140 return 0;
1141 }
1142
1143 if (likely(p->real_parent == p->parent) && likely(p->signal)) {
1144 struct signal_struct *psig;
1145 struct signal_struct *sig;
1146
1147 /*
1148 * The resource counters for the group leader are in its
1149 * own task_struct. Those for dead threads in the group
1150 * are in its signal_struct, as are those for the child
1151 * processes it has previously reaped. All these
1152 * accumulate in the parent's signal_struct c* fields.
1153 *
1154 * We don't bother to take a lock here to protect these
1155 * p->signal fields, because they are only touched by
1156 * __exit_signal, which runs with tasklist_lock
1157 * write-locked anyway, and so is excluded here. We do
1158 * need to protect the access to p->parent->signal fields,
1159 * as other threads in the parent group can be right
1160 * here reaping other children at the same time.
1161 */
1162 spin_lock_irq(&p->parent->sighand->siglock);
1163 psig = p->parent->signal;
1164 sig = p->signal;
1165 psig->cutime =
1166 cputime_add(psig->cutime,
1167 cputime_add(p->utime,
1168 cputime_add(sig->utime,
1169 sig->cutime)));
1170 psig->cstime =
1171 cputime_add(psig->cstime,
1172 cputime_add(p->stime,
1173 cputime_add(sig->stime,
1174 sig->cstime)));
1175 psig->cmin_flt +=
1176 p->min_flt + sig->min_flt + sig->cmin_flt;
1177 psig->cmaj_flt +=
1178 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1179 psig->cnvcsw +=
1180 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1181 psig->cnivcsw +=
1182 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1183 spin_unlock_irq(&p->parent->sighand->siglock);
1184 }
1185
1186 /*
1187 * Now we are sure this task is interesting, and no other
1188 * thread can reap it because we set its state to EXIT_DEAD.
1189 */
1190 read_unlock(&tasklist_lock);
1191
1192 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1193 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1194 ? p->signal->group_exit_code : p->exit_code;
1195 if (!retval && stat_addr)
1196 retval = put_user(status, stat_addr);
1197 if (!retval && infop)
1198 retval = put_user(SIGCHLD, &infop->si_signo);
1199 if (!retval && infop)
1200 retval = put_user(0, &infop->si_errno);
1201 if (!retval && infop) {
1202 int why;
1203
1204 if ((status & 0x7f) == 0) {
1205 why = CLD_EXITED;
1206 status >>= 8;
1207 } else {
1208 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1209 status &= 0x7f;
1210 }
1211 retval = put_user((short)why, &infop->si_code);
1212 if (!retval)
1213 retval = put_user(status, &infop->si_status);
1214 }
1215 if (!retval && infop)
1216 retval = put_user(p->pid, &infop->si_pid);
1217 if (!retval && infop)
1218 retval = put_user(p->uid, &infop->si_uid);
1219 if (retval) {
1220 // TODO: is this safe?
1221 p->exit_state = EXIT_ZOMBIE;
1222 return retval;
1223 }
1224 retval = p->pid;
1225 if (p->real_parent != p->parent) {
1226 write_lock_irq(&tasklist_lock);
1227 /* Double-check with lock held. */
1228 if (p->real_parent != p->parent) {
1229 __ptrace_unlink(p);
1230 // TODO: is this safe?
1231 p->exit_state = EXIT_ZOMBIE;
1232 /*
1233 * If this is not a detached task, notify the parent.
1234 * If it's still not detached after that, don't release
1235 * it now.
1236 */
1237 if (p->exit_signal != -1) {
1238 do_notify_parent(p, p->exit_signal);
1239 if (p->exit_signal != -1)
1240 p = NULL;
1241 }
1242 }
1243 write_unlock_irq(&tasklist_lock);
1244 }
1245 if (p != NULL)
1246 release_task(p);
1247 BUG_ON(!retval);
1248 return retval;
1249 }
1250
1251 /*
1252 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1253 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1254 * the lock and this task is uninteresting. If we return nonzero, we have
1255 * released the lock and the system call should return.
1256 */
1257 static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
1258 int noreap, struct siginfo __user *infop,
1259 int __user *stat_addr, struct rusage __user *ru)
1260 {
1261 int retval, exit_code;
1262
1263 if (!p->exit_code)
1264 return 0;
1265 if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1266 p->signal && p->signal->group_stop_count > 0)
1267 /*
1268 * A group stop is in progress and this is the group leader.
1269 * We won't report until all threads have stopped.
1270 */
1271 return 0;
1272
1273 /*
1274 * Now we are pretty sure this task is interesting.
1275 * Make sure it doesn't get reaped out from under us while we
1276 * give up the lock and then examine it below. We don't want to
1277 * keep holding onto the tasklist_lock while we call getrusage and
1278 * possibly take page faults for user memory.
1279 */
1280 get_task_struct(p);
1281 read_unlock(&tasklist_lock);
1282
1283 if (unlikely(noreap)) {
1284 pid_t pid = p->pid;
1285 uid_t uid = p->uid;
1286 int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
1287
1288 exit_code = p->exit_code;
1289 if (unlikely(!exit_code) ||
1290 unlikely(p->state & TASK_TRACED))
1291 goto bail_ref;
1292 return wait_noreap_copyout(p, pid, uid,
1293 why, (exit_code << 8) | 0x7f,
1294 infop, ru);
1295 }
1296
1297 write_lock_irq(&tasklist_lock);
1298
1299 /*
1300 * This uses xchg to be atomic with the thread resuming and setting
1301 * it. It must also be done with the write lock held to prevent a
1302 * race with the EXIT_ZOMBIE case.
1303 */
1304 exit_code = xchg(&p->exit_code, 0);
1305 if (unlikely(p->exit_state)) {
1306 /*
1307 * The task resumed and then died. Let the next iteration
1308 * catch it in EXIT_ZOMBIE. Note that exit_code might
1309 * already be zero here if it resumed and did _exit(0).
1310 * The task itself is dead and won't touch exit_code again;
1311 * other processors in this function are locked out.
1312 */
1313 p->exit_code = exit_code;
1314 exit_code = 0;
1315 }
1316 if (unlikely(exit_code == 0)) {
1317 /*
1318 * Another thread in this function got to it first, or it
1319 * resumed, or it resumed and then died.
1320 */
1321 write_unlock_irq(&tasklist_lock);
1322 bail_ref:
1323 put_task_struct(p);
1324 /*
1325 * We are returning to the wait loop without having successfully
1326 * removed the process and having released the lock. We cannot
1327 * continue, since the "p" task pointer is potentially stale.
1328 *
1329 * Return -EAGAIN, and do_wait() will restart the loop from the
1330 * beginning. Do _not_ re-acquire the lock.
1331 */
1332 return -EAGAIN;
1333 }
1334
1335 /* move to end of parent's list to avoid starvation */
1336 remove_parent(p);
1337 add_parent(p);
1338
1339 write_unlock_irq(&tasklist_lock);
1340
1341 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1342 if (!retval && stat_addr)
1343 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1344 if (!retval && infop)
1345 retval = put_user(SIGCHLD, &infop->si_signo);
1346 if (!retval && infop)
1347 retval = put_user(0, &infop->si_errno);
1348 if (!retval && infop)
1349 retval = put_user((short)((p->ptrace & PT_PTRACED)
1350 ? CLD_TRAPPED : CLD_STOPPED),
1351 &infop->si_code);
1352 if (!retval && infop)
1353 retval = put_user(exit_code, &infop->si_status);
1354 if (!retval && infop)
1355 retval = put_user(p->pid, &infop->si_pid);
1356 if (!retval && infop)
1357 retval = put_user(p->uid, &infop->si_uid);
1358 if (!retval)
1359 retval = p->pid;
1360 put_task_struct(p);
1361
1362 BUG_ON(!retval);
1363 return retval;
1364 }
1365
1366 /*
1367 * Handle do_wait work for one task in a live, non-stopped state.
1368 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1369 * the lock and this task is uninteresting. If we return nonzero, we have
1370 * released the lock and the system call should return.
1371 */
1372 static int wait_task_continued(struct task_struct *p, int noreap,
1373 struct siginfo __user *infop,
1374 int __user *stat_addr, struct rusage __user *ru)
1375 {
1376 int retval;
1377 pid_t pid;
1378 uid_t uid;
1379
1380 if (unlikely(!p->signal))
1381 return 0;
1382
1383 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1384 return 0;
1385
1386 spin_lock_irq(&p->sighand->siglock);
1387 /* Re-check with the lock held. */
1388 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1389 spin_unlock_irq(&p->sighand->siglock);
1390 return 0;
1391 }
1392 if (!noreap)
1393 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1394 spin_unlock_irq(&p->sighand->siglock);
1395
1396 pid = p->pid;
1397 uid = p->uid;
1398 get_task_struct(p);
1399 read_unlock(&tasklist_lock);
1400
1401 if (!infop) {
1402 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1403 put_task_struct(p);
1404 if (!retval && stat_addr)
1405 retval = put_user(0xffff, stat_addr);
1406 if (!retval)
1407 retval = p->pid;
1408 } else {
1409 retval = wait_noreap_copyout(p, pid, uid,
1410 CLD_CONTINUED, SIGCONT,
1411 infop, ru);
1412 BUG_ON(retval == 0);
1413 }
1414
1415 return retval;
1416 }
1417
1418
1419 static inline int my_ptrace_child(struct task_struct *p)
1420 {
1421 if (!(p->ptrace & PT_PTRACED))
1422 return 0;
1423 if (!(p->ptrace & PT_ATTACHED))
1424 return 1;
1425 /*
1426 * This child was PTRACE_ATTACH'd. We should be seeing it only if
1427 * we are the attacher. If we are the real parent, this is a race
1428 * inside ptrace_attach. It is waiting for the tasklist_lock,
1429 * which we have to switch the parent links, but has already set
1430 * the flags in p->ptrace.
1431 */
1432 return (p->parent != p->real_parent);
1433 }
1434
1435 static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
1436 int __user *stat_addr, struct rusage __user *ru)
1437 {
1438 DECLARE_WAITQUEUE(wait, current);
1439 struct task_struct *tsk;
1440 int flag, retval;
1441
1442 add_wait_queue(&current->signal->wait_chldexit,&wait);
1443 repeat:
1444 /*
1445 * We will set this flag if we see any child that might later
1446 * match our criteria, even if we are not able to reap it yet.
1447 */
1448 flag = 0;
1449 current->state = TASK_INTERRUPTIBLE;
1450 read_lock(&tasklist_lock);
1451 tsk = current;
1452 do {
1453 struct task_struct *p;
1454 struct list_head *_p;
1455 int ret;
1456
1457 list_for_each(_p,&tsk->children) {
1458 p = list_entry(_p, struct task_struct, sibling);
1459
1460 ret = eligible_child(pid, options, p);
1461 if (!ret)
1462 continue;
1463
1464 switch (p->state) {
1465 case TASK_TRACED:
1466 /*
1467 * When we hit the race with PTRACE_ATTACH,
1468 * we will not report this child. But the
1469 * race means it has not yet been moved to
1470 * our ptrace_children list, so we need to
1471 * set the flag here to avoid a spurious ECHILD
1472 * when the race happens with the only child.
1473 */
1474 flag = 1;
1475 if (!my_ptrace_child(p))
1476 continue;
1477 /*FALLTHROUGH*/
1478 case TASK_STOPPED:
1479 /*
1480 * It's stopped now, so it might later
1481 * continue, exit, or stop again.
1482 */
1483 flag = 1;
1484 if (!(options & WUNTRACED) &&
1485 !my_ptrace_child(p))
1486 continue;
1487 retval = wait_task_stopped(p, ret == 2,
1488 (options & WNOWAIT),
1489 infop,
1490 stat_addr, ru);
1491 if (retval == -EAGAIN)
1492 goto repeat;
1493 if (retval != 0) /* He released the lock. */
1494 goto end;
1495 break;
1496 default:
1497 // case EXIT_DEAD:
1498 if (p->exit_state == EXIT_DEAD)
1499 continue;
1500 // case EXIT_ZOMBIE:
1501 if (p->exit_state == EXIT_ZOMBIE) {
1502 /*
1503 * Eligible but we cannot release
1504 * it yet:
1505 */
1506 if (ret == 2)
1507 goto check_continued;
1508 if (!likely(options & WEXITED))
1509 continue;
1510 retval = wait_task_zombie(
1511 p, (options & WNOWAIT),
1512 infop, stat_addr, ru);
1513 /* He released the lock. */
1514 if (retval != 0)
1515 goto end;
1516 break;
1517 }
1518 check_continued:
1519 /*
1520 * It's running now, so it might later
1521 * exit, stop, or stop and then continue.
1522 */
1523 flag = 1;
1524 if (!unlikely(options & WCONTINUED))
1525 continue;
1526 retval = wait_task_continued(
1527 p, (options & WNOWAIT),
1528 infop, stat_addr, ru);
1529 if (retval != 0) /* He released the lock. */
1530 goto end;
1531 break;
1532 }
1533 }
1534 if (!flag) {
1535 list_for_each(_p, &tsk->ptrace_children) {
1536 p = list_entry(_p, struct task_struct,
1537 ptrace_list);
1538 if (!eligible_child(pid, options, p))
1539 continue;
1540 flag = 1;
1541 break;
1542 }
1543 }
1544 if (options & __WNOTHREAD)
1545 break;
1546 tsk = next_thread(tsk);
1547 BUG_ON(tsk->signal != current->signal);
1548 } while (tsk != current);
1549
1550 read_unlock(&tasklist_lock);
1551 if (flag) {
1552 retval = 0;
1553 if (options & WNOHANG)
1554 goto end;
1555 retval = -ERESTARTSYS;
1556 if (signal_pending(current))
1557 goto end;
1558 schedule();
1559 goto repeat;
1560 }
1561 retval = -ECHILD;
1562 end:
1563 current->state = TASK_RUNNING;
1564 remove_wait_queue(&current->signal->wait_chldexit,&wait);
1565 if (infop) {
1566 if (retval > 0)
1567 retval = 0;
1568 else {
1569 /*
1570 * For a WNOHANG return, clear out all the fields
1571 * we would set so the user can easily tell the
1572 * difference.
1573 */
1574 if (!retval)
1575 retval = put_user(0, &infop->si_signo);
1576 if (!retval)
1577 retval = put_user(0, &infop->si_errno);
1578 if (!retval)
1579 retval = put_user(0, &infop->si_code);
1580 if (!retval)
1581 retval = put_user(0, &infop->si_pid);
1582 if (!retval)
1583 retval = put_user(0, &infop->si_uid);
1584 if (!retval)
1585 retval = put_user(0, &infop->si_status);
1586 }
1587 }
1588 return retval;
1589 }
1590
1591 asmlinkage long sys_waitid(int which, pid_t pid,
1592 struct siginfo __user *infop, int options,
1593 struct rusage __user *ru)
1594 {
1595 long ret;
1596
1597 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1598 return -EINVAL;
1599 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1600 return -EINVAL;
1601
1602 switch (which) {
1603 case P_ALL:
1604 pid = -1;
1605 break;
1606 case P_PID:
1607 if (pid <= 0)
1608 return -EINVAL;
1609 break;
1610 case P_PGID:
1611 if (pid <= 0)
1612 return -EINVAL;
1613 pid = -pid;
1614 break;
1615 default:
1616 return -EINVAL;
1617 }
1618
1619 ret = do_wait(pid, options, infop, NULL, ru);
1620
1621 /* avoid REGPARM breakage on x86: */
1622 prevent_tail_call(ret);
1623 return ret;
1624 }
1625
1626 asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
1627 int options, struct rusage __user *ru)
1628 {
1629 long ret;
1630
1631 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1632 __WNOTHREAD|__WCLONE|__WALL))
1633 return -EINVAL;
1634 ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
1635
1636 /* avoid REGPARM breakage on x86: */
1637 prevent_tail_call(ret);
1638 return ret;
1639 }
1640
1641 #ifdef __ARCH_WANT_SYS_WAITPID
1642
1643 /*
1644 * sys_waitpid() remains for compatibility. waitpid() should be
1645 * implemented by calling sys_wait4() from libc.a.
1646 */
1647 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1648 {
1649 return sys_wait4(pid, stat_addr, options, NULL);
1650 }
1651
1652 #endif