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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/module.h>
11#include <linux/capability.h>
12#include <linux/completion.h>
13#include <linux/personality.h>
14#include <linux/tty.h>
15#include <linux/iocontext.h>
16#include <linux/key.h>
17#include <linux/security.h>
18#include <linux/cpu.h>
19#include <linux/acct.h>
20#include <linux/tsacct_kern.h>
21#include <linux/file.h>
22#include <linux/fdtable.h>
23#include <linux/freezer.h>
24#include <linux/binfmts.h>
25#include <linux/nsproxy.h>
26#include <linux/pid_namespace.h>
27#include <linux/ptrace.h>
28#include <linux/profile.h>
29#include <linux/mount.h>
30#include <linux/proc_fs.h>
31#include <linux/kthread.h>
32#include <linux/mempolicy.h>
33#include <linux/taskstats_kern.h>
34#include <linux/delayacct.h>
35#include <linux/cgroup.h>
36#include <linux/syscalls.h>
37#include <linux/signal.h>
38#include <linux/posix-timers.h>
39#include <linux/cn_proc.h>
40#include <linux/mutex.h>
41#include <linux/futex.h>
42#include <linux/pipe_fs_i.h>
43#include <linux/audit.h> /* for audit_free() */
44#include <linux/resource.h>
45#include <linux/blkdev.h>
46#include <linux/task_io_accounting_ops.h>
47#include <linux/tracehook.h>
48#include <linux/fs_struct.h>
49#include <linux/init_task.h>
50#include <linux/perf_event.h>
51#include <trace/events/sched.h>
52#include <linux/hw_breakpoint.h>
53#include <linux/oom.h>
54#include <linux/writeback.h>
55#include <linux/shm.h>
56#include <linux/kcov.h>
57#include <linux/random.h>
58
59#include <linux/uaccess.h>
60#include <asm/unistd.h>
61#include <asm/pgtable.h>
62#include <asm/mmu_context.h>
63
64static void __unhash_process(struct task_struct *p, bool group_dead)
65{
66 nr_threads--;
67 detach_pid(p, PIDTYPE_PID);
68 if (group_dead) {
69 detach_pid(p, PIDTYPE_PGID);
70 detach_pid(p, PIDTYPE_SID);
71
72 list_del_rcu(&p->tasks);
73 list_del_init(&p->sibling);
74 __this_cpu_dec(process_counts);
75 }
76 list_del_rcu(&p->thread_group);
77 list_del_rcu(&p->thread_node);
78}
79
80/*
81 * This function expects the tasklist_lock write-locked.
82 */
83static void __exit_signal(struct task_struct *tsk)
84{
85 struct signal_struct *sig = tsk->signal;
86 bool group_dead = thread_group_leader(tsk);
87 struct sighand_struct *sighand;
88 struct tty_struct *uninitialized_var(tty);
89 cputime_t utime, stime;
90
91 sighand = rcu_dereference_check(tsk->sighand,
92 lockdep_tasklist_lock_is_held());
93 spin_lock(&sighand->siglock);
94
95#ifdef CONFIG_POSIX_TIMERS
96 posix_cpu_timers_exit(tsk);
97 if (group_dead) {
98 posix_cpu_timers_exit_group(tsk);
99 } else {
100 /*
101 * This can only happen if the caller is de_thread().
102 * FIXME: this is the temporary hack, we should teach
103 * posix-cpu-timers to handle this case correctly.
104 */
105 if (unlikely(has_group_leader_pid(tsk)))
106 posix_cpu_timers_exit_group(tsk);
107 }
108#endif
109
110 if (group_dead) {
111 tty = sig->tty;
112 sig->tty = NULL;
113 } else {
114 /*
115 * If there is any task waiting for the group exit
116 * then notify it:
117 */
118 if (sig->notify_count > 0 && !--sig->notify_count)
119 wake_up_process(sig->group_exit_task);
120
121 if (tsk == sig->curr_target)
122 sig->curr_target = next_thread(tsk);
123 }
124
125 add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
126 sizeof(unsigned long long));
127
128 /*
129 * Accumulate here the counters for all threads as they die. We could
130 * skip the group leader because it is the last user of signal_struct,
131 * but we want to avoid the race with thread_group_cputime() which can
132 * see the empty ->thread_head list.
133 */
134 task_cputime(tsk, &utime, &stime);
135 write_seqlock(&sig->stats_lock);
136 sig->utime += utime;
137 sig->stime += stime;
138 sig->gtime += task_gtime(tsk);
139 sig->min_flt += tsk->min_flt;
140 sig->maj_flt += tsk->maj_flt;
141 sig->nvcsw += tsk->nvcsw;
142 sig->nivcsw += tsk->nivcsw;
143 sig->inblock += task_io_get_inblock(tsk);
144 sig->oublock += task_io_get_oublock(tsk);
145 task_io_accounting_add(&sig->ioac, &tsk->ioac);
146 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
147 sig->nr_threads--;
148 __unhash_process(tsk, group_dead);
149 write_sequnlock(&sig->stats_lock);
150
151 /*
152 * Do this under ->siglock, we can race with another thread
153 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
154 */
155 flush_sigqueue(&tsk->pending);
156 tsk->sighand = NULL;
157 spin_unlock(&sighand->siglock);
158
159 __cleanup_sighand(sighand);
160 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
161 if (group_dead) {
162 flush_sigqueue(&sig->shared_pending);
163 tty_kref_put(tty);
164 }
165}
166
167static void delayed_put_task_struct(struct rcu_head *rhp)
168{
169 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
170
171 perf_event_delayed_put(tsk);
172 trace_sched_process_free(tsk);
173 put_task_struct(tsk);
174}
175
176
177void release_task(struct task_struct *p)
178{
179 struct task_struct *leader;
180 int zap_leader;
181repeat:
182 /* don't need to get the RCU readlock here - the process is dead and
183 * can't be modifying its own credentials. But shut RCU-lockdep up */
184 rcu_read_lock();
185 atomic_dec(&__task_cred(p)->user->processes);
186 rcu_read_unlock();
187
188 proc_flush_task(p);
189
190 write_lock_irq(&tasklist_lock);
191 ptrace_release_task(p);
192 __exit_signal(p);
193
194 /*
195 * If we are the last non-leader member of the thread
196 * group, and the leader is zombie, then notify the
197 * group leader's parent process. (if it wants notification.)
198 */
199 zap_leader = 0;
200 leader = p->group_leader;
201 if (leader != p && thread_group_empty(leader)
202 && leader->exit_state == EXIT_ZOMBIE) {
203 /*
204 * If we were the last child thread and the leader has
205 * exited already, and the leader's parent ignores SIGCHLD,
206 * then we are the one who should release the leader.
207 */
208 zap_leader = do_notify_parent(leader, leader->exit_signal);
209 if (zap_leader)
210 leader->exit_state = EXIT_DEAD;
211 }
212
213 write_unlock_irq(&tasklist_lock);
214 release_thread(p);
215 call_rcu(&p->rcu, delayed_put_task_struct);
216
217 p = leader;
218 if (unlikely(zap_leader))
219 goto repeat;
220}
221
222/*
223 * Note that if this function returns a valid task_struct pointer (!NULL)
224 * task->usage must remain >0 for the duration of the RCU critical section.
225 */
226struct task_struct *task_rcu_dereference(struct task_struct **ptask)
227{
228 struct sighand_struct *sighand;
229 struct task_struct *task;
230
231 /*
232 * We need to verify that release_task() was not called and thus
233 * delayed_put_task_struct() can't run and drop the last reference
234 * before rcu_read_unlock(). We check task->sighand != NULL,
235 * but we can read the already freed and reused memory.
236 */
237retry:
238 task = rcu_dereference(*ptask);
239 if (!task)
240 return NULL;
241
242 probe_kernel_address(&task->sighand, sighand);
243
244 /*
245 * Pairs with atomic_dec_and_test() in put_task_struct(). If this task
246 * was already freed we can not miss the preceding update of this
247 * pointer.
248 */
249 smp_rmb();
250 if (unlikely(task != READ_ONCE(*ptask)))
251 goto retry;
252
253 /*
254 * We've re-checked that "task == *ptask", now we have two different
255 * cases:
256 *
257 * 1. This is actually the same task/task_struct. In this case
258 * sighand != NULL tells us it is still alive.
259 *
260 * 2. This is another task which got the same memory for task_struct.
261 * We can't know this of course, and we can not trust
262 * sighand != NULL.
263 *
264 * In this case we actually return a random value, but this is
265 * correct.
266 *
267 * If we return NULL - we can pretend that we actually noticed that
268 * *ptask was updated when the previous task has exited. Or pretend
269 * that probe_slab_address(&sighand) reads NULL.
270 *
271 * If we return the new task (because sighand is not NULL for any
272 * reason) - this is fine too. This (new) task can't go away before
273 * another gp pass.
274 *
275 * And note: We could even eliminate the false positive if re-read
276 * task->sighand once again to avoid the falsely NULL. But this case
277 * is very unlikely so we don't care.
278 */
279 if (!sighand)
280 return NULL;
281
282 return task;
283}
284
285struct task_struct *try_get_task_struct(struct task_struct **ptask)
286{
287 struct task_struct *task;
288
289 rcu_read_lock();
290 task = task_rcu_dereference(ptask);
291 if (task)
292 get_task_struct(task);
293 rcu_read_unlock();
294
295 return task;
296}
297
298/*
299 * Determine if a process group is "orphaned", according to the POSIX
300 * definition in 2.2.2.52. Orphaned process groups are not to be affected
301 * by terminal-generated stop signals. Newly orphaned process groups are
302 * to receive a SIGHUP and a SIGCONT.
303 *
304 * "I ask you, have you ever known what it is to be an orphan?"
305 */
306static int will_become_orphaned_pgrp(struct pid *pgrp,
307 struct task_struct *ignored_task)
308{
309 struct task_struct *p;
310
311 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
312 if ((p == ignored_task) ||
313 (p->exit_state && thread_group_empty(p)) ||
314 is_global_init(p->real_parent))
315 continue;
316
317 if (task_pgrp(p->real_parent) != pgrp &&
318 task_session(p->real_parent) == task_session(p))
319 return 0;
320 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
321
322 return 1;
323}
324
325int is_current_pgrp_orphaned(void)
326{
327 int retval;
328
329 read_lock(&tasklist_lock);
330 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
331 read_unlock(&tasklist_lock);
332
333 return retval;
334}
335
336static bool has_stopped_jobs(struct pid *pgrp)
337{
338 struct task_struct *p;
339
340 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
341 if (p->signal->flags & SIGNAL_STOP_STOPPED)
342 return true;
343 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
344
345 return false;
346}
347
348/*
349 * Check to see if any process groups have become orphaned as
350 * a result of our exiting, and if they have any stopped jobs,
351 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
352 */
353static void
354kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
355{
356 struct pid *pgrp = task_pgrp(tsk);
357 struct task_struct *ignored_task = tsk;
358
359 if (!parent)
360 /* exit: our father is in a different pgrp than
361 * we are and we were the only connection outside.
362 */
363 parent = tsk->real_parent;
364 else
365 /* reparent: our child is in a different pgrp than
366 * we are, and it was the only connection outside.
367 */
368 ignored_task = NULL;
369
370 if (task_pgrp(parent) != pgrp &&
371 task_session(parent) == task_session(tsk) &&
372 will_become_orphaned_pgrp(pgrp, ignored_task) &&
373 has_stopped_jobs(pgrp)) {
374 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
375 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
376 }
377}
378
379#ifdef CONFIG_MEMCG
380/*
381 * A task is exiting. If it owned this mm, find a new owner for the mm.
382 */
383void mm_update_next_owner(struct mm_struct *mm)
384{
385 struct task_struct *c, *g, *p = current;
386
387retry:
388 /*
389 * If the exiting or execing task is not the owner, it's
390 * someone else's problem.
391 */
392 if (mm->owner != p)
393 return;
394 /*
395 * The current owner is exiting/execing and there are no other
396 * candidates. Do not leave the mm pointing to a possibly
397 * freed task structure.
398 */
399 if (atomic_read(&mm->mm_users) <= 1) {
400 mm->owner = NULL;
401 return;
402 }
403
404 read_lock(&tasklist_lock);
405 /*
406 * Search in the children
407 */
408 list_for_each_entry(c, &p->children, sibling) {
409 if (c->mm == mm)
410 goto assign_new_owner;
411 }
412
413 /*
414 * Search in the siblings
415 */
416 list_for_each_entry(c, &p->real_parent->children, sibling) {
417 if (c->mm == mm)
418 goto assign_new_owner;
419 }
420
421 /*
422 * Search through everything else, we should not get here often.
423 */
424 for_each_process(g) {
425 if (g->flags & PF_KTHREAD)
426 continue;
427 for_each_thread(g, c) {
428 if (c->mm == mm)
429 goto assign_new_owner;
430 if (c->mm)
431 break;
432 }
433 }
434 read_unlock(&tasklist_lock);
435 /*
436 * We found no owner yet mm_users > 1: this implies that we are
437 * most likely racing with swapoff (try_to_unuse()) or /proc or
438 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
439 */
440 mm->owner = NULL;
441 return;
442
443assign_new_owner:
444 BUG_ON(c == p);
445 get_task_struct(c);
446 /*
447 * The task_lock protects c->mm from changing.
448 * We always want mm->owner->mm == mm
449 */
450 task_lock(c);
451 /*
452 * Delay read_unlock() till we have the task_lock()
453 * to ensure that c does not slip away underneath us
454 */
455 read_unlock(&tasklist_lock);
456 if (c->mm != mm) {
457 task_unlock(c);
458 put_task_struct(c);
459 goto retry;
460 }
461 mm->owner = c;
462 task_unlock(c);
463 put_task_struct(c);
464}
465#endif /* CONFIG_MEMCG */
466
467/*
468 * Turn us into a lazy TLB process if we
469 * aren't already..
470 */
471static void exit_mm(struct task_struct *tsk)
472{
473 struct mm_struct *mm = tsk->mm;
474 struct core_state *core_state;
475
476 mm_release(tsk, mm);
477 if (!mm)
478 return;
479 sync_mm_rss(mm);
480 /*
481 * Serialize with any possible pending coredump.
482 * We must hold mmap_sem around checking core_state
483 * and clearing tsk->mm. The core-inducing thread
484 * will increment ->nr_threads for each thread in the
485 * group with ->mm != NULL.
486 */
487 down_read(&mm->mmap_sem);
488 core_state = mm->core_state;
489 if (core_state) {
490 struct core_thread self;
491
492 up_read(&mm->mmap_sem);
493
494 self.task = tsk;
495 self.next = xchg(&core_state->dumper.next, &self);
496 /*
497 * Implies mb(), the result of xchg() must be visible
498 * to core_state->dumper.
499 */
500 if (atomic_dec_and_test(&core_state->nr_threads))
501 complete(&core_state->startup);
502
503 for (;;) {
504 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
505 if (!self.task) /* see coredump_finish() */
506 break;
507 freezable_schedule();
508 }
509 __set_task_state(tsk, TASK_RUNNING);
510 down_read(&mm->mmap_sem);
511 }
512 atomic_inc(&mm->mm_count);
513 BUG_ON(mm != tsk->active_mm);
514 /* more a memory barrier than a real lock */
515 task_lock(tsk);
516 tsk->mm = NULL;
517 up_read(&mm->mmap_sem);
518 enter_lazy_tlb(mm, current);
519 task_unlock(tsk);
520 mm_update_next_owner(mm);
521 mmput(mm);
522 if (test_thread_flag(TIF_MEMDIE))
523 exit_oom_victim();
524}
525
526static struct task_struct *find_alive_thread(struct task_struct *p)
527{
528 struct task_struct *t;
529
530 for_each_thread(p, t) {
531 if (!(t->flags & PF_EXITING))
532 return t;
533 }
534 return NULL;
535}
536
537static struct task_struct *find_child_reaper(struct task_struct *father)
538 __releases(&tasklist_lock)
539 __acquires(&tasklist_lock)
540{
541 struct pid_namespace *pid_ns = task_active_pid_ns(father);
542 struct task_struct *reaper = pid_ns->child_reaper;
543
544 if (likely(reaper != father))
545 return reaper;
546
547 reaper = find_alive_thread(father);
548 if (reaper) {
549 pid_ns->child_reaper = reaper;
550 return reaper;
551 }
552
553 write_unlock_irq(&tasklist_lock);
554 if (unlikely(pid_ns == &init_pid_ns)) {
555 panic("Attempted to kill init! exitcode=0x%08x\n",
556 father->signal->group_exit_code ?: father->exit_code);
557 }
558 zap_pid_ns_processes(pid_ns);
559 write_lock_irq(&tasklist_lock);
560
561 return father;
562}
563
564/*
565 * When we die, we re-parent all our children, and try to:
566 * 1. give them to another thread in our thread group, if such a member exists
567 * 2. give it to the first ancestor process which prctl'd itself as a
568 * child_subreaper for its children (like a service manager)
569 * 3. give it to the init process (PID 1) in our pid namespace
570 */
571static struct task_struct *find_new_reaper(struct task_struct *father,
572 struct task_struct *child_reaper)
573{
574 struct task_struct *thread, *reaper;
575
576 thread = find_alive_thread(father);
577 if (thread)
578 return thread;
579
580 if (father->signal->has_child_subreaper) {
581 /*
582 * Find the first ->is_child_subreaper ancestor in our pid_ns.
583 * We start from father to ensure we can not look into another
584 * namespace, this is safe because all its threads are dead.
585 */
586 for (reaper = father;
587 !same_thread_group(reaper, child_reaper);
588 reaper = reaper->real_parent) {
589 /* call_usermodehelper() descendants need this check */
590 if (reaper == &init_task)
591 break;
592 if (!reaper->signal->is_child_subreaper)
593 continue;
594 thread = find_alive_thread(reaper);
595 if (thread)
596 return thread;
597 }
598 }
599
600 return child_reaper;
601}
602
603/*
604* Any that need to be release_task'd are put on the @dead list.
605 */
606static void reparent_leader(struct task_struct *father, struct task_struct *p,
607 struct list_head *dead)
608{
609 if (unlikely(p->exit_state == EXIT_DEAD))
610 return;
611
612 /* We don't want people slaying init. */
613 p->exit_signal = SIGCHLD;
614
615 /* If it has exited notify the new parent about this child's death. */
616 if (!p->ptrace &&
617 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
618 if (do_notify_parent(p, p->exit_signal)) {
619 p->exit_state = EXIT_DEAD;
620 list_add(&p->ptrace_entry, dead);
621 }
622 }
623
624 kill_orphaned_pgrp(p, father);
625}
626
627/*
628 * This does two things:
629 *
630 * A. Make init inherit all the child processes
631 * B. Check to see if any process groups have become orphaned
632 * as a result of our exiting, and if they have any stopped
633 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
634 */
635static void forget_original_parent(struct task_struct *father,
636 struct list_head *dead)
637{
638 struct task_struct *p, *t, *reaper;
639
640 if (unlikely(!list_empty(&father->ptraced)))
641 exit_ptrace(father, dead);
642
643 /* Can drop and reacquire tasklist_lock */
644 reaper = find_child_reaper(father);
645 if (list_empty(&father->children))
646 return;
647
648 reaper = find_new_reaper(father, reaper);
649 list_for_each_entry(p, &father->children, sibling) {
650 for_each_thread(p, t) {
651 t->real_parent = reaper;
652 BUG_ON((!t->ptrace) != (t->parent == father));
653 if (likely(!t->ptrace))
654 t->parent = t->real_parent;
655 if (t->pdeath_signal)
656 group_send_sig_info(t->pdeath_signal,
657 SEND_SIG_NOINFO, t);
658 }
659 /*
660 * If this is a threaded reparent there is no need to
661 * notify anyone anything has happened.
662 */
663 if (!same_thread_group(reaper, father))
664 reparent_leader(father, p, dead);
665 }
666 list_splice_tail_init(&father->children, &reaper->children);
667}
668
669/*
670 * Send signals to all our closest relatives so that they know
671 * to properly mourn us..
672 */
673static void exit_notify(struct task_struct *tsk, int group_dead)
674{
675 bool autoreap;
676 struct task_struct *p, *n;
677 LIST_HEAD(dead);
678
679 write_lock_irq(&tasklist_lock);
680 forget_original_parent(tsk, &dead);
681
682 if (group_dead)
683 kill_orphaned_pgrp(tsk->group_leader, NULL);
684
685 if (unlikely(tsk->ptrace)) {
686 int sig = thread_group_leader(tsk) &&
687 thread_group_empty(tsk) &&
688 !ptrace_reparented(tsk) ?
689 tsk->exit_signal : SIGCHLD;
690 autoreap = do_notify_parent(tsk, sig);
691 } else if (thread_group_leader(tsk)) {
692 autoreap = thread_group_empty(tsk) &&
693 do_notify_parent(tsk, tsk->exit_signal);
694 } else {
695 autoreap = true;
696 }
697
698 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
699 if (tsk->exit_state == EXIT_DEAD)
700 list_add(&tsk->ptrace_entry, &dead);
701
702 /* mt-exec, de_thread() is waiting for group leader */
703 if (unlikely(tsk->signal->notify_count < 0))
704 wake_up_process(tsk->signal->group_exit_task);
705 write_unlock_irq(&tasklist_lock);
706
707 list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
708 list_del_init(&p->ptrace_entry);
709 release_task(p);
710 }
711}
712
713#ifdef CONFIG_DEBUG_STACK_USAGE
714static void check_stack_usage(void)
715{
716 static DEFINE_SPINLOCK(low_water_lock);
717 static int lowest_to_date = THREAD_SIZE;
718 unsigned long free;
719
720 free = stack_not_used(current);
721
722 if (free >= lowest_to_date)
723 return;
724
725 spin_lock(&low_water_lock);
726 if (free < lowest_to_date) {
727 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
728 current->comm, task_pid_nr(current), free);
729 lowest_to_date = free;
730 }
731 spin_unlock(&low_water_lock);
732}
733#else
734static inline void check_stack_usage(void) {}
735#endif
736
737void __noreturn do_exit(long code)
738{
739 struct task_struct *tsk = current;
740 int group_dead;
741 TASKS_RCU(int tasks_rcu_i);
742
743 profile_task_exit(tsk);
744 kcov_task_exit(tsk);
745
746 WARN_ON(blk_needs_flush_plug(tsk));
747
748 if (unlikely(in_interrupt()))
749 panic("Aiee, killing interrupt handler!");
750 if (unlikely(!tsk->pid))
751 panic("Attempted to kill the idle task!");
752
753 /*
754 * If do_exit is called because this processes oopsed, it's possible
755 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
756 * continuing. Amongst other possible reasons, this is to prevent
757 * mm_release()->clear_child_tid() from writing to a user-controlled
758 * kernel address.
759 */
760 set_fs(USER_DS);
761
762 ptrace_event(PTRACE_EVENT_EXIT, code);
763
764 validate_creds_for_do_exit(tsk);
765
766 /*
767 * We're taking recursive faults here in do_exit. Safest is to just
768 * leave this task alone and wait for reboot.
769 */
770 if (unlikely(tsk->flags & PF_EXITING)) {
771 pr_alert("Fixing recursive fault but reboot is needed!\n");
772 /*
773 * We can do this unlocked here. The futex code uses
774 * this flag just to verify whether the pi state
775 * cleanup has been done or not. In the worst case it
776 * loops once more. We pretend that the cleanup was
777 * done as there is no way to return. Either the
778 * OWNER_DIED bit is set by now or we push the blocked
779 * task into the wait for ever nirwana as well.
780 */
781 tsk->flags |= PF_EXITPIDONE;
782 set_current_state(TASK_UNINTERRUPTIBLE);
783 schedule();
784 }
785
786 exit_signals(tsk); /* sets PF_EXITING */
787 /*
788 * Ensure that all new tsk->pi_lock acquisitions must observe
789 * PF_EXITING. Serializes against futex.c:attach_to_pi_owner().
790 */
791 smp_mb();
792 /*
793 * Ensure that we must observe the pi_state in exit_mm() ->
794 * mm_release() -> exit_pi_state_list().
795 */
796 raw_spin_unlock_wait(&tsk->pi_lock);
797
798 if (unlikely(in_atomic())) {
799 pr_info("note: %s[%d] exited with preempt_count %d\n",
800 current->comm, task_pid_nr(current),
801 preempt_count());
802 preempt_count_set(PREEMPT_ENABLED);
803 }
804
805 /* sync mm's RSS info before statistics gathering */
806 if (tsk->mm)
807 sync_mm_rss(tsk->mm);
808 acct_update_integrals(tsk);
809 group_dead = atomic_dec_and_test(&tsk->signal->live);
810 if (group_dead) {
811#ifdef CONFIG_POSIX_TIMERS
812 hrtimer_cancel(&tsk->signal->real_timer);
813 exit_itimers(tsk->signal);
814#endif
815 if (tsk->mm)
816 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
817 }
818 acct_collect(code, group_dead);
819 if (group_dead)
820 tty_audit_exit();
821 audit_free(tsk);
822
823 tsk->exit_code = code;
824 taskstats_exit(tsk, group_dead);
825
826 exit_mm(tsk);
827
828 if (group_dead)
829 acct_process();
830 trace_sched_process_exit(tsk);
831
832 exit_sem(tsk);
833 exit_shm(tsk);
834 exit_files(tsk);
835 exit_fs(tsk);
836 if (group_dead)
837 disassociate_ctty(1);
838 exit_task_namespaces(tsk);
839 exit_task_work(tsk);
840 exit_thread(tsk);
841
842 /*
843 * Flush inherited counters to the parent - before the parent
844 * gets woken up by child-exit notifications.
845 *
846 * because of cgroup mode, must be called before cgroup_exit()
847 */
848 perf_event_exit_task(tsk);
849
850 sched_autogroup_exit_task(tsk);
851 cgroup_exit(tsk);
852
853 /*
854 * FIXME: do that only when needed, using sched_exit tracepoint
855 */
856 flush_ptrace_hw_breakpoint(tsk);
857
858 TASKS_RCU(preempt_disable());
859 TASKS_RCU(tasks_rcu_i = __srcu_read_lock(&tasks_rcu_exit_srcu));
860 TASKS_RCU(preempt_enable());
861 exit_notify(tsk, group_dead);
862 proc_exit_connector(tsk);
863 mpol_put_task_policy(tsk);
864#ifdef CONFIG_FUTEX
865 if (unlikely(current->pi_state_cache))
866 kfree(current->pi_state_cache);
867#endif
868 /*
869 * Make sure we are holding no locks:
870 */
871 debug_check_no_locks_held();
872 /*
873 * We can do this unlocked here. The futex code uses this flag
874 * just to verify whether the pi state cleanup has been done
875 * or not. In the worst case it loops once more.
876 */
877 tsk->flags |= PF_EXITPIDONE;
878
879 if (tsk->io_context)
880 exit_io_context(tsk);
881
882 if (tsk->splice_pipe)
883 free_pipe_info(tsk->splice_pipe);
884
885 if (tsk->task_frag.page)
886 put_page(tsk->task_frag.page);
887
888 validate_creds_for_do_exit(tsk);
889
890 check_stack_usage();
891 preempt_disable();
892 if (tsk->nr_dirtied)
893 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
894 exit_rcu();
895 TASKS_RCU(__srcu_read_unlock(&tasks_rcu_exit_srcu, tasks_rcu_i));
896
897 do_task_dead();
898}
899EXPORT_SYMBOL_GPL(do_exit);
900
901void complete_and_exit(struct completion *comp, long code)
902{
903 if (comp)
904 complete(comp);
905
906 do_exit(code);
907}
908EXPORT_SYMBOL(complete_and_exit);
909
910SYSCALL_DEFINE1(exit, int, error_code)
911{
912 do_exit((error_code&0xff)<<8);
913}
914
915/*
916 * Take down every thread in the group. This is called by fatal signals
917 * as well as by sys_exit_group (below).
918 */
919void
920do_group_exit(int exit_code)
921{
922 struct signal_struct *sig = current->signal;
923
924 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
925
926 if (signal_group_exit(sig))
927 exit_code = sig->group_exit_code;
928 else if (!thread_group_empty(current)) {
929 struct sighand_struct *const sighand = current->sighand;
930
931 spin_lock_irq(&sighand->siglock);
932 if (signal_group_exit(sig))
933 /* Another thread got here before we took the lock. */
934 exit_code = sig->group_exit_code;
935 else {
936 sig->group_exit_code = exit_code;
937 sig->flags = SIGNAL_GROUP_EXIT;
938 zap_other_threads(current);
939 }
940 spin_unlock_irq(&sighand->siglock);
941 }
942
943 do_exit(exit_code);
944 /* NOTREACHED */
945}
946
947/*
948 * this kills every thread in the thread group. Note that any externally
949 * wait4()-ing process will get the correct exit code - even if this
950 * thread is not the thread group leader.
951 */
952SYSCALL_DEFINE1(exit_group, int, error_code)
953{
954 do_group_exit((error_code & 0xff) << 8);
955 /* NOTREACHED */
956 return 0;
957}
958
959struct wait_opts {
960 enum pid_type wo_type;
961 int wo_flags;
962 struct pid *wo_pid;
963
964 struct siginfo __user *wo_info;
965 int __user *wo_stat;
966 struct rusage __user *wo_rusage;
967
968 wait_queue_t child_wait;
969 int notask_error;
970};
971
972static inline
973struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
974{
975 if (type != PIDTYPE_PID)
976 task = task->group_leader;
977 return task->pids[type].pid;
978}
979
980static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
981{
982 return wo->wo_type == PIDTYPE_MAX ||
983 task_pid_type(p, wo->wo_type) == wo->wo_pid;
984}
985
986static int
987eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
988{
989 if (!eligible_pid(wo, p))
990 return 0;
991
992 /*
993 * Wait for all children (clone and not) if __WALL is set or
994 * if it is traced by us.
995 */
996 if (ptrace || (wo->wo_flags & __WALL))
997 return 1;
998
999 /*
1000 * Otherwise, wait for clone children *only* if __WCLONE is set;
1001 * otherwise, wait for non-clone children *only*.
1002 *
1003 * Note: a "clone" child here is one that reports to its parent
1004 * using a signal other than SIGCHLD, or a non-leader thread which
1005 * we can only see if it is traced by us.
1006 */
1007 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
1008 return 0;
1009
1010 return 1;
1011}
1012
1013static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
1014 pid_t pid, uid_t uid, int why, int status)
1015{
1016 struct siginfo __user *infop;
1017 int retval = wo->wo_rusage
1018 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1019
1020 put_task_struct(p);
1021 infop = wo->wo_info;
1022 if (infop) {
1023 if (!retval)
1024 retval = put_user(SIGCHLD, &infop->si_signo);
1025 if (!retval)
1026 retval = put_user(0, &infop->si_errno);
1027 if (!retval)
1028 retval = put_user((short)why, &infop->si_code);
1029 if (!retval)
1030 retval = put_user(pid, &infop->si_pid);
1031 if (!retval)
1032 retval = put_user(uid, &infop->si_uid);
1033 if (!retval)
1034 retval = put_user(status, &infop->si_status);
1035 }
1036 if (!retval)
1037 retval = pid;
1038 return retval;
1039}
1040
1041/*
1042 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1043 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1044 * the lock and this task is uninteresting. If we return nonzero, we have
1045 * released the lock and the system call should return.
1046 */
1047static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1048{
1049 int state, retval, status;
1050 pid_t pid = task_pid_vnr(p);
1051 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1052 struct siginfo __user *infop;
1053
1054 if (!likely(wo->wo_flags & WEXITED))
1055 return 0;
1056
1057 if (unlikely(wo->wo_flags & WNOWAIT)) {
1058 int exit_code = p->exit_code;
1059 int why;
1060
1061 get_task_struct(p);
1062 read_unlock(&tasklist_lock);
1063 sched_annotate_sleep();
1064
1065 if ((exit_code & 0x7f) == 0) {
1066 why = CLD_EXITED;
1067 status = exit_code >> 8;
1068 } else {
1069 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1070 status = exit_code & 0x7f;
1071 }
1072 return wait_noreap_copyout(wo, p, pid, uid, why, status);
1073 }
1074 /*
1075 * Move the task's state to DEAD/TRACE, only one thread can do this.
1076 */
1077 state = (ptrace_reparented(p) && thread_group_leader(p)) ?
1078 EXIT_TRACE : EXIT_DEAD;
1079 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1080 return 0;
1081 /*
1082 * We own this thread, nobody else can reap it.
1083 */
1084 read_unlock(&tasklist_lock);
1085 sched_annotate_sleep();
1086
1087 /*
1088 * Check thread_group_leader() to exclude the traced sub-threads.
1089 */
1090 if (state == EXIT_DEAD && thread_group_leader(p)) {
1091 struct signal_struct *sig = p->signal;
1092 struct signal_struct *psig = current->signal;
1093 unsigned long maxrss;
1094 cputime_t tgutime, tgstime;
1095
1096 /*
1097 * The resource counters for the group leader are in its
1098 * own task_struct. Those for dead threads in the group
1099 * are in its signal_struct, as are those for the child
1100 * processes it has previously reaped. All these
1101 * accumulate in the parent's signal_struct c* fields.
1102 *
1103 * We don't bother to take a lock here to protect these
1104 * p->signal fields because the whole thread group is dead
1105 * and nobody can change them.
1106 *
1107 * psig->stats_lock also protects us from our sub-theads
1108 * which can reap other children at the same time. Until
1109 * we change k_getrusage()-like users to rely on this lock
1110 * we have to take ->siglock as well.
1111 *
1112 * We use thread_group_cputime_adjusted() to get times for
1113 * the thread group, which consolidates times for all threads
1114 * in the group including the group leader.
1115 */
1116 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1117 spin_lock_irq(¤t->sighand->siglock);
1118 write_seqlock(&psig->stats_lock);
1119 psig->cutime += tgutime + sig->cutime;
1120 psig->cstime += tgstime + sig->cstime;
1121 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1122 psig->cmin_flt +=
1123 p->min_flt + sig->min_flt + sig->cmin_flt;
1124 psig->cmaj_flt +=
1125 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1126 psig->cnvcsw +=
1127 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1128 psig->cnivcsw +=
1129 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1130 psig->cinblock +=
1131 task_io_get_inblock(p) +
1132 sig->inblock + sig->cinblock;
1133 psig->coublock +=
1134 task_io_get_oublock(p) +
1135 sig->oublock + sig->coublock;
1136 maxrss = max(sig->maxrss, sig->cmaxrss);
1137 if (psig->cmaxrss < maxrss)
1138 psig->cmaxrss = maxrss;
1139 task_io_accounting_add(&psig->ioac, &p->ioac);
1140 task_io_accounting_add(&psig->ioac, &sig->ioac);
1141 write_sequnlock(&psig->stats_lock);
1142 spin_unlock_irq(¤t->sighand->siglock);
1143 }
1144
1145 retval = wo->wo_rusage
1146 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1147 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1148 ? p->signal->group_exit_code : p->exit_code;
1149 if (!retval && wo->wo_stat)
1150 retval = put_user(status, wo->wo_stat);
1151
1152 infop = wo->wo_info;
1153 if (!retval && infop)
1154 retval = put_user(SIGCHLD, &infop->si_signo);
1155 if (!retval && infop)
1156 retval = put_user(0, &infop->si_errno);
1157 if (!retval && infop) {
1158 int why;
1159
1160 if ((status & 0x7f) == 0) {
1161 why = CLD_EXITED;
1162 status >>= 8;
1163 } else {
1164 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1165 status &= 0x7f;
1166 }
1167 retval = put_user((short)why, &infop->si_code);
1168 if (!retval)
1169 retval = put_user(status, &infop->si_status);
1170 }
1171 if (!retval && infop)
1172 retval = put_user(pid, &infop->si_pid);
1173 if (!retval && infop)
1174 retval = put_user(uid, &infop->si_uid);
1175 if (!retval)
1176 retval = pid;
1177
1178 if (state == EXIT_TRACE) {
1179 write_lock_irq(&tasklist_lock);
1180 /* We dropped tasklist, ptracer could die and untrace */
1181 ptrace_unlink(p);
1182
1183 /* If parent wants a zombie, don't release it now */
1184 state = EXIT_ZOMBIE;
1185 if (do_notify_parent(p, p->exit_signal))
1186 state = EXIT_DEAD;
1187 p->exit_state = state;
1188 write_unlock_irq(&tasklist_lock);
1189 }
1190 if (state == EXIT_DEAD)
1191 release_task(p);
1192
1193 return retval;
1194}
1195
1196static int *task_stopped_code(struct task_struct *p, bool ptrace)
1197{
1198 if (ptrace) {
1199 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING))
1200 return &p->exit_code;
1201 } else {
1202 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1203 return &p->signal->group_exit_code;
1204 }
1205 return NULL;
1206}
1207
1208/**
1209 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1210 * @wo: wait options
1211 * @ptrace: is the wait for ptrace
1212 * @p: task to wait for
1213 *
1214 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1215 *
1216 * CONTEXT:
1217 * read_lock(&tasklist_lock), which is released if return value is
1218 * non-zero. Also, grabs and releases @p->sighand->siglock.
1219 *
1220 * RETURNS:
1221 * 0 if wait condition didn't exist and search for other wait conditions
1222 * should continue. Non-zero return, -errno on failure and @p's pid on
1223 * success, implies that tasklist_lock is released and wait condition
1224 * search should terminate.
1225 */
1226static int wait_task_stopped(struct wait_opts *wo,
1227 int ptrace, struct task_struct *p)
1228{
1229 struct siginfo __user *infop;
1230 int retval, exit_code, *p_code, why;
1231 uid_t uid = 0; /* unneeded, required by compiler */
1232 pid_t pid;
1233
1234 /*
1235 * Traditionally we see ptrace'd stopped tasks regardless of options.
1236 */
1237 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1238 return 0;
1239
1240 if (!task_stopped_code(p, ptrace))
1241 return 0;
1242
1243 exit_code = 0;
1244 spin_lock_irq(&p->sighand->siglock);
1245
1246 p_code = task_stopped_code(p, ptrace);
1247 if (unlikely(!p_code))
1248 goto unlock_sig;
1249
1250 exit_code = *p_code;
1251 if (!exit_code)
1252 goto unlock_sig;
1253
1254 if (!unlikely(wo->wo_flags & WNOWAIT))
1255 *p_code = 0;
1256
1257 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1258unlock_sig:
1259 spin_unlock_irq(&p->sighand->siglock);
1260 if (!exit_code)
1261 return 0;
1262
1263 /*
1264 * Now we are pretty sure this task is interesting.
1265 * Make sure it doesn't get reaped out from under us while we
1266 * give up the lock and then examine it below. We don't want to
1267 * keep holding onto the tasklist_lock while we call getrusage and
1268 * possibly take page faults for user memory.
1269 */
1270 get_task_struct(p);
1271 pid = task_pid_vnr(p);
1272 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1273 read_unlock(&tasklist_lock);
1274 sched_annotate_sleep();
1275
1276 if (unlikely(wo->wo_flags & WNOWAIT))
1277 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
1278
1279 retval = wo->wo_rusage
1280 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1281 if (!retval && wo->wo_stat)
1282 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
1283
1284 infop = wo->wo_info;
1285 if (!retval && infop)
1286 retval = put_user(SIGCHLD, &infop->si_signo);
1287 if (!retval && infop)
1288 retval = put_user(0, &infop->si_errno);
1289 if (!retval && infop)
1290 retval = put_user((short)why, &infop->si_code);
1291 if (!retval && infop)
1292 retval = put_user(exit_code, &infop->si_status);
1293 if (!retval && infop)
1294 retval = put_user(pid, &infop->si_pid);
1295 if (!retval && infop)
1296 retval = put_user(uid, &infop->si_uid);
1297 if (!retval)
1298 retval = pid;
1299 put_task_struct(p);
1300
1301 BUG_ON(!retval);
1302 return retval;
1303}
1304
1305/*
1306 * Handle do_wait work for one task in a live, non-stopped state.
1307 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1308 * the lock and this task is uninteresting. If we return nonzero, we have
1309 * released the lock and the system call should return.
1310 */
1311static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1312{
1313 int retval;
1314 pid_t pid;
1315 uid_t uid;
1316
1317 if (!unlikely(wo->wo_flags & WCONTINUED))
1318 return 0;
1319
1320 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1321 return 0;
1322
1323 spin_lock_irq(&p->sighand->siglock);
1324 /* Re-check with the lock held. */
1325 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1326 spin_unlock_irq(&p->sighand->siglock);
1327 return 0;
1328 }
1329 if (!unlikely(wo->wo_flags & WNOWAIT))
1330 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1331 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1332 spin_unlock_irq(&p->sighand->siglock);
1333
1334 pid = task_pid_vnr(p);
1335 get_task_struct(p);
1336 read_unlock(&tasklist_lock);
1337 sched_annotate_sleep();
1338
1339 if (!wo->wo_info) {
1340 retval = wo->wo_rusage
1341 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1342 put_task_struct(p);
1343 if (!retval && wo->wo_stat)
1344 retval = put_user(0xffff, wo->wo_stat);
1345 if (!retval)
1346 retval = pid;
1347 } else {
1348 retval = wait_noreap_copyout(wo, p, pid, uid,
1349 CLD_CONTINUED, SIGCONT);
1350 BUG_ON(retval == 0);
1351 }
1352
1353 return retval;
1354}
1355
1356/*
1357 * Consider @p for a wait by @parent.
1358 *
1359 * -ECHILD should be in ->notask_error before the first call.
1360 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1361 * Returns zero if the search for a child should continue;
1362 * then ->notask_error is 0 if @p is an eligible child,
1363 * or another error from security_task_wait(), or still -ECHILD.
1364 */
1365static int wait_consider_task(struct wait_opts *wo, int ptrace,
1366 struct task_struct *p)
1367{
1368 /*
1369 * We can race with wait_task_zombie() from another thread.
1370 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1371 * can't confuse the checks below.
1372 */
1373 int exit_state = ACCESS_ONCE(p->exit_state);
1374 int ret;
1375
1376 if (unlikely(exit_state == EXIT_DEAD))
1377 return 0;
1378
1379 ret = eligible_child(wo, ptrace, p);
1380 if (!ret)
1381 return ret;
1382
1383 ret = security_task_wait(p);
1384 if (unlikely(ret < 0)) {
1385 /*
1386 * If we have not yet seen any eligible child,
1387 * then let this error code replace -ECHILD.
1388 * A permission error will give the user a clue
1389 * to look for security policy problems, rather
1390 * than for mysterious wait bugs.
1391 */
1392 if (wo->notask_error)
1393 wo->notask_error = ret;
1394 return 0;
1395 }
1396
1397 if (unlikely(exit_state == EXIT_TRACE)) {
1398 /*
1399 * ptrace == 0 means we are the natural parent. In this case
1400 * we should clear notask_error, debugger will notify us.
1401 */
1402 if (likely(!ptrace))
1403 wo->notask_error = 0;
1404 return 0;
1405 }
1406
1407 if (likely(!ptrace) && unlikely(p->ptrace)) {
1408 /*
1409 * If it is traced by its real parent's group, just pretend
1410 * the caller is ptrace_do_wait() and reap this child if it
1411 * is zombie.
1412 *
1413 * This also hides group stop state from real parent; otherwise
1414 * a single stop can be reported twice as group and ptrace stop.
1415 * If a ptracer wants to distinguish these two events for its
1416 * own children it should create a separate process which takes
1417 * the role of real parent.
1418 */
1419 if (!ptrace_reparented(p))
1420 ptrace = 1;
1421 }
1422
1423 /* slay zombie? */
1424 if (exit_state == EXIT_ZOMBIE) {
1425 /* we don't reap group leaders with subthreads */
1426 if (!delay_group_leader(p)) {
1427 /*
1428 * A zombie ptracee is only visible to its ptracer.
1429 * Notification and reaping will be cascaded to the
1430 * real parent when the ptracer detaches.
1431 */
1432 if (unlikely(ptrace) || likely(!p->ptrace))
1433 return wait_task_zombie(wo, p);
1434 }
1435
1436 /*
1437 * Allow access to stopped/continued state via zombie by
1438 * falling through. Clearing of notask_error is complex.
1439 *
1440 * When !@ptrace:
1441 *
1442 * If WEXITED is set, notask_error should naturally be
1443 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1444 * so, if there are live subthreads, there are events to
1445 * wait for. If all subthreads are dead, it's still safe
1446 * to clear - this function will be called again in finite
1447 * amount time once all the subthreads are released and
1448 * will then return without clearing.
1449 *
1450 * When @ptrace:
1451 *
1452 * Stopped state is per-task and thus can't change once the
1453 * target task dies. Only continued and exited can happen.
1454 * Clear notask_error if WCONTINUED | WEXITED.
1455 */
1456 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1457 wo->notask_error = 0;
1458 } else {
1459 /*
1460 * @p is alive and it's gonna stop, continue or exit, so
1461 * there always is something to wait for.
1462 */
1463 wo->notask_error = 0;
1464 }
1465
1466 /*
1467 * Wait for stopped. Depending on @ptrace, different stopped state
1468 * is used and the two don't interact with each other.
1469 */
1470 ret = wait_task_stopped(wo, ptrace, p);
1471 if (ret)
1472 return ret;
1473
1474 /*
1475 * Wait for continued. There's only one continued state and the
1476 * ptracer can consume it which can confuse the real parent. Don't
1477 * use WCONTINUED from ptracer. You don't need or want it.
1478 */
1479 return wait_task_continued(wo, p);
1480}
1481
1482/*
1483 * Do the work of do_wait() for one thread in the group, @tsk.
1484 *
1485 * -ECHILD should be in ->notask_error before the first call.
1486 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1487 * Returns zero if the search for a child should continue; then
1488 * ->notask_error is 0 if there were any eligible children,
1489 * or another error from security_task_wait(), or still -ECHILD.
1490 */
1491static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1492{
1493 struct task_struct *p;
1494
1495 list_for_each_entry(p, &tsk->children, sibling) {
1496 int ret = wait_consider_task(wo, 0, p);
1497
1498 if (ret)
1499 return ret;
1500 }
1501
1502 return 0;
1503}
1504
1505static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1506{
1507 struct task_struct *p;
1508
1509 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1510 int ret = wait_consider_task(wo, 1, p);
1511
1512 if (ret)
1513 return ret;
1514 }
1515
1516 return 0;
1517}
1518
1519static int child_wait_callback(wait_queue_t *wait, unsigned mode,
1520 int sync, void *key)
1521{
1522 struct wait_opts *wo = container_of(wait, struct wait_opts,
1523 child_wait);
1524 struct task_struct *p = key;
1525
1526 if (!eligible_pid(wo, p))
1527 return 0;
1528
1529 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1530 return 0;
1531
1532 return default_wake_function(wait, mode, sync, key);
1533}
1534
1535void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1536{
1537 __wake_up_sync_key(&parent->signal->wait_chldexit,
1538 TASK_INTERRUPTIBLE, 1, p);
1539}
1540
1541static long do_wait(struct wait_opts *wo)
1542{
1543 struct task_struct *tsk;
1544 int retval;
1545
1546 trace_sched_process_wait(wo->wo_pid);
1547
1548 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1549 wo->child_wait.private = current;
1550 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1551repeat:
1552 /*
1553 * If there is nothing that can match our criteria, just get out.
1554 * We will clear ->notask_error to zero if we see any child that
1555 * might later match our criteria, even if we are not able to reap
1556 * it yet.
1557 */
1558 wo->notask_error = -ECHILD;
1559 if ((wo->wo_type < PIDTYPE_MAX) &&
1560 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1561 goto notask;
1562
1563 set_current_state(TASK_INTERRUPTIBLE);
1564 read_lock(&tasklist_lock);
1565 tsk = current;
1566 do {
1567 retval = do_wait_thread(wo, tsk);
1568 if (retval)
1569 goto end;
1570
1571 retval = ptrace_do_wait(wo, tsk);
1572 if (retval)
1573 goto end;
1574
1575 if (wo->wo_flags & __WNOTHREAD)
1576 break;
1577 } while_each_thread(current, tsk);
1578 read_unlock(&tasklist_lock);
1579
1580notask:
1581 retval = wo->notask_error;
1582 if (!retval && !(wo->wo_flags & WNOHANG)) {
1583 retval = -ERESTARTSYS;
1584 if (!signal_pending(current)) {
1585 schedule();
1586 goto repeat;
1587 }
1588 }
1589end:
1590 __set_current_state(TASK_RUNNING);
1591 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1592 return retval;
1593}
1594
1595SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1596 infop, int, options, struct rusage __user *, ru)
1597{
1598 struct wait_opts wo;
1599 struct pid *pid = NULL;
1600 enum pid_type type;
1601 long ret;
1602
1603 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
1604 __WNOTHREAD|__WCLONE|__WALL))
1605 return -EINVAL;
1606 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1607 return -EINVAL;
1608
1609 switch (which) {
1610 case P_ALL:
1611 type = PIDTYPE_MAX;
1612 break;
1613 case P_PID:
1614 type = PIDTYPE_PID;
1615 if (upid <= 0)
1616 return -EINVAL;
1617 break;
1618 case P_PGID:
1619 type = PIDTYPE_PGID;
1620 if (upid <= 0)
1621 return -EINVAL;
1622 break;
1623 default:
1624 return -EINVAL;
1625 }
1626
1627 if (type < PIDTYPE_MAX)
1628 pid = find_get_pid(upid);
1629
1630 wo.wo_type = type;
1631 wo.wo_pid = pid;
1632 wo.wo_flags = options;
1633 wo.wo_info = infop;
1634 wo.wo_stat = NULL;
1635 wo.wo_rusage = ru;
1636 ret = do_wait(&wo);
1637
1638 if (ret > 0) {
1639 ret = 0;
1640 } else if (infop) {
1641 /*
1642 * For a WNOHANG return, clear out all the fields
1643 * we would set so the user can easily tell the
1644 * difference.
1645 */
1646 if (!ret)
1647 ret = put_user(0, &infop->si_signo);
1648 if (!ret)
1649 ret = put_user(0, &infop->si_errno);
1650 if (!ret)
1651 ret = put_user(0, &infop->si_code);
1652 if (!ret)
1653 ret = put_user(0, &infop->si_pid);
1654 if (!ret)
1655 ret = put_user(0, &infop->si_uid);
1656 if (!ret)
1657 ret = put_user(0, &infop->si_status);
1658 }
1659
1660 put_pid(pid);
1661 return ret;
1662}
1663
1664SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1665 int, options, struct rusage __user *, ru)
1666{
1667 struct wait_opts wo;
1668 struct pid *pid = NULL;
1669 enum pid_type type;
1670 long ret;
1671
1672 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1673 __WNOTHREAD|__WCLONE|__WALL))
1674 return -EINVAL;
1675
1676 if (upid == -1)
1677 type = PIDTYPE_MAX;
1678 else if (upid < 0) {
1679 type = PIDTYPE_PGID;
1680 pid = find_get_pid(-upid);
1681 } else if (upid == 0) {
1682 type = PIDTYPE_PGID;
1683 pid = get_task_pid(current, PIDTYPE_PGID);
1684 } else /* upid > 0 */ {
1685 type = PIDTYPE_PID;
1686 pid = find_get_pid(upid);
1687 }
1688
1689 wo.wo_type = type;
1690 wo.wo_pid = pid;
1691 wo.wo_flags = options | WEXITED;
1692 wo.wo_info = NULL;
1693 wo.wo_stat = stat_addr;
1694 wo.wo_rusage = ru;
1695 ret = do_wait(&wo);
1696 put_pid(pid);
1697
1698 return ret;
1699}
1700
1701#ifdef __ARCH_WANT_SYS_WAITPID
1702
1703/*
1704 * sys_waitpid() remains for compatibility. waitpid() should be
1705 * implemented by calling sys_wait4() from libc.a.
1706 */
1707SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1708{
1709 return sys_wait4(pid, stat_addr, options, NULL);
1710}
1711
1712#endif
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/module.h>
11#include <linux/capability.h>
12#include <linux/completion.h>
13#include <linux/personality.h>
14#include <linux/tty.h>
15#include <linux/iocontext.h>
16#include <linux/key.h>
17#include <linux/security.h>
18#include <linux/cpu.h>
19#include <linux/acct.h>
20#include <linux/tsacct_kern.h>
21#include <linux/file.h>
22#include <linux/fdtable.h>
23#include <linux/binfmts.h>
24#include <linux/nsproxy.h>
25#include <linux/pid_namespace.h>
26#include <linux/ptrace.h>
27#include <linux/profile.h>
28#include <linux/mount.h>
29#include <linux/proc_fs.h>
30#include <linux/kthread.h>
31#include <linux/mempolicy.h>
32#include <linux/taskstats_kern.h>
33#include <linux/delayacct.h>
34#include <linux/freezer.h>
35#include <linux/cgroup.h>
36#include <linux/syscalls.h>
37#include <linux/signal.h>
38#include <linux/posix-timers.h>
39#include <linux/cn_proc.h>
40#include <linux/mutex.h>
41#include <linux/futex.h>
42#include <linux/pipe_fs_i.h>
43#include <linux/audit.h> /* for audit_free() */
44#include <linux/resource.h>
45#include <linux/blkdev.h>
46#include <linux/task_io_accounting_ops.h>
47#include <linux/tracehook.h>
48#include <linux/fs_struct.h>
49#include <linux/init_task.h>
50#include <linux/perf_event.h>
51#include <trace/events/sched.h>
52#include <linux/hw_breakpoint.h>
53#include <linux/oom.h>
54
55#include <asm/uaccess.h>
56#include <asm/unistd.h>
57#include <asm/pgtable.h>
58#include <asm/mmu_context.h>
59
60static void exit_mm(struct task_struct * tsk);
61
62static void __unhash_process(struct task_struct *p, bool group_dead)
63{
64 nr_threads--;
65 detach_pid(p, PIDTYPE_PID);
66 if (group_dead) {
67 detach_pid(p, PIDTYPE_PGID);
68 detach_pid(p, PIDTYPE_SID);
69
70 list_del_rcu(&p->tasks);
71 list_del_init(&p->sibling);
72 __this_cpu_dec(process_counts);
73 }
74 list_del_rcu(&p->thread_group);
75}
76
77/*
78 * This function expects the tasklist_lock write-locked.
79 */
80static void __exit_signal(struct task_struct *tsk)
81{
82 struct signal_struct *sig = tsk->signal;
83 bool group_dead = thread_group_leader(tsk);
84 struct sighand_struct *sighand;
85 struct tty_struct *uninitialized_var(tty);
86
87 sighand = rcu_dereference_check(tsk->sighand,
88 lockdep_tasklist_lock_is_held());
89 spin_lock(&sighand->siglock);
90
91 posix_cpu_timers_exit(tsk);
92 if (group_dead) {
93 posix_cpu_timers_exit_group(tsk);
94 tty = sig->tty;
95 sig->tty = NULL;
96 } else {
97 /*
98 * This can only happen if the caller is de_thread().
99 * FIXME: this is the temporary hack, we should teach
100 * posix-cpu-timers to handle this case correctly.
101 */
102 if (unlikely(has_group_leader_pid(tsk)))
103 posix_cpu_timers_exit_group(tsk);
104
105 /*
106 * If there is any task waiting for the group exit
107 * then notify it:
108 */
109 if (sig->notify_count > 0 && !--sig->notify_count)
110 wake_up_process(sig->group_exit_task);
111
112 if (tsk == sig->curr_target)
113 sig->curr_target = next_thread(tsk);
114 /*
115 * Accumulate here the counters for all threads but the
116 * group leader as they die, so they can be added into
117 * the process-wide totals when those are taken.
118 * The group leader stays around as a zombie as long
119 * as there are other threads. When it gets reaped,
120 * the exit.c code will add its counts into these totals.
121 * We won't ever get here for the group leader, since it
122 * will have been the last reference on the signal_struct.
123 */
124 sig->utime = cputime_add(sig->utime, tsk->utime);
125 sig->stime = cputime_add(sig->stime, tsk->stime);
126 sig->gtime = cputime_add(sig->gtime, tsk->gtime);
127 sig->min_flt += tsk->min_flt;
128 sig->maj_flt += tsk->maj_flt;
129 sig->nvcsw += tsk->nvcsw;
130 sig->nivcsw += tsk->nivcsw;
131 sig->inblock += task_io_get_inblock(tsk);
132 sig->oublock += task_io_get_oublock(tsk);
133 task_io_accounting_add(&sig->ioac, &tsk->ioac);
134 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
135 }
136
137 sig->nr_threads--;
138 __unhash_process(tsk, group_dead);
139
140 /*
141 * Do this under ->siglock, we can race with another thread
142 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
143 */
144 flush_sigqueue(&tsk->pending);
145 tsk->sighand = NULL;
146 spin_unlock(&sighand->siglock);
147
148 __cleanup_sighand(sighand);
149 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
150 if (group_dead) {
151 flush_sigqueue(&sig->shared_pending);
152 tty_kref_put(tty);
153 }
154}
155
156static void delayed_put_task_struct(struct rcu_head *rhp)
157{
158 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
159
160 perf_event_delayed_put(tsk);
161 trace_sched_process_free(tsk);
162 put_task_struct(tsk);
163}
164
165
166void release_task(struct task_struct * p)
167{
168 struct task_struct *leader;
169 int zap_leader;
170repeat:
171 /* don't need to get the RCU readlock here - the process is dead and
172 * can't be modifying its own credentials. But shut RCU-lockdep up */
173 rcu_read_lock();
174 atomic_dec(&__task_cred(p)->user->processes);
175 rcu_read_unlock();
176
177 proc_flush_task(p);
178
179 write_lock_irq(&tasklist_lock);
180 ptrace_release_task(p);
181 __exit_signal(p);
182
183 /*
184 * If we are the last non-leader member of the thread
185 * group, and the leader is zombie, then notify the
186 * group leader's parent process. (if it wants notification.)
187 */
188 zap_leader = 0;
189 leader = p->group_leader;
190 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
191 /*
192 * If we were the last child thread and the leader has
193 * exited already, and the leader's parent ignores SIGCHLD,
194 * then we are the one who should release the leader.
195 */
196 zap_leader = do_notify_parent(leader, leader->exit_signal);
197 if (zap_leader)
198 leader->exit_state = EXIT_DEAD;
199 }
200
201 write_unlock_irq(&tasklist_lock);
202 release_thread(p);
203 call_rcu(&p->rcu, delayed_put_task_struct);
204
205 p = leader;
206 if (unlikely(zap_leader))
207 goto repeat;
208}
209
210/*
211 * This checks not only the pgrp, but falls back on the pid if no
212 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
213 * without this...
214 *
215 * The caller must hold rcu lock or the tasklist lock.
216 */
217struct pid *session_of_pgrp(struct pid *pgrp)
218{
219 struct task_struct *p;
220 struct pid *sid = NULL;
221
222 p = pid_task(pgrp, PIDTYPE_PGID);
223 if (p == NULL)
224 p = pid_task(pgrp, PIDTYPE_PID);
225 if (p != NULL)
226 sid = task_session(p);
227
228 return sid;
229}
230
231/*
232 * Determine if a process group is "orphaned", according to the POSIX
233 * definition in 2.2.2.52. Orphaned process groups are not to be affected
234 * by terminal-generated stop signals. Newly orphaned process groups are
235 * to receive a SIGHUP and a SIGCONT.
236 *
237 * "I ask you, have you ever known what it is to be an orphan?"
238 */
239static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
240{
241 struct task_struct *p;
242
243 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
244 if ((p == ignored_task) ||
245 (p->exit_state && thread_group_empty(p)) ||
246 is_global_init(p->real_parent))
247 continue;
248
249 if (task_pgrp(p->real_parent) != pgrp &&
250 task_session(p->real_parent) == task_session(p))
251 return 0;
252 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
253
254 return 1;
255}
256
257int is_current_pgrp_orphaned(void)
258{
259 int retval;
260
261 read_lock(&tasklist_lock);
262 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
263 read_unlock(&tasklist_lock);
264
265 return retval;
266}
267
268static bool has_stopped_jobs(struct pid *pgrp)
269{
270 struct task_struct *p;
271
272 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
273 if (p->signal->flags & SIGNAL_STOP_STOPPED)
274 return true;
275 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
276
277 return false;
278}
279
280/*
281 * Check to see if any process groups have become orphaned as
282 * a result of our exiting, and if they have any stopped jobs,
283 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
284 */
285static void
286kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
287{
288 struct pid *pgrp = task_pgrp(tsk);
289 struct task_struct *ignored_task = tsk;
290
291 if (!parent)
292 /* exit: our father is in a different pgrp than
293 * we are and we were the only connection outside.
294 */
295 parent = tsk->real_parent;
296 else
297 /* reparent: our child is in a different pgrp than
298 * we are, and it was the only connection outside.
299 */
300 ignored_task = NULL;
301
302 if (task_pgrp(parent) != pgrp &&
303 task_session(parent) == task_session(tsk) &&
304 will_become_orphaned_pgrp(pgrp, ignored_task) &&
305 has_stopped_jobs(pgrp)) {
306 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
307 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
308 }
309}
310
311/**
312 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
313 *
314 * If a kernel thread is launched as a result of a system call, or if
315 * it ever exits, it should generally reparent itself to kthreadd so it
316 * isn't in the way of other processes and is correctly cleaned up on exit.
317 *
318 * The various task state such as scheduling policy and priority may have
319 * been inherited from a user process, so we reset them to sane values here.
320 *
321 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
322 */
323static void reparent_to_kthreadd(void)
324{
325 write_lock_irq(&tasklist_lock);
326
327 ptrace_unlink(current);
328 /* Reparent to init */
329 current->real_parent = current->parent = kthreadd_task;
330 list_move_tail(¤t->sibling, ¤t->real_parent->children);
331
332 /* Set the exit signal to SIGCHLD so we signal init on exit */
333 current->exit_signal = SIGCHLD;
334
335 if (task_nice(current) < 0)
336 set_user_nice(current, 0);
337 /* cpus_allowed? */
338 /* rt_priority? */
339 /* signals? */
340 memcpy(current->signal->rlim, init_task.signal->rlim,
341 sizeof(current->signal->rlim));
342
343 atomic_inc(&init_cred.usage);
344 commit_creds(&init_cred);
345 write_unlock_irq(&tasklist_lock);
346}
347
348void __set_special_pids(struct pid *pid)
349{
350 struct task_struct *curr = current->group_leader;
351
352 if (task_session(curr) != pid)
353 change_pid(curr, PIDTYPE_SID, pid);
354
355 if (task_pgrp(curr) != pid)
356 change_pid(curr, PIDTYPE_PGID, pid);
357}
358
359static void set_special_pids(struct pid *pid)
360{
361 write_lock_irq(&tasklist_lock);
362 __set_special_pids(pid);
363 write_unlock_irq(&tasklist_lock);
364}
365
366/*
367 * Let kernel threads use this to say that they allow a certain signal.
368 * Must not be used if kthread was cloned with CLONE_SIGHAND.
369 */
370int allow_signal(int sig)
371{
372 if (!valid_signal(sig) || sig < 1)
373 return -EINVAL;
374
375 spin_lock_irq(¤t->sighand->siglock);
376 /* This is only needed for daemonize()'ed kthreads */
377 sigdelset(¤t->blocked, sig);
378 /*
379 * Kernel threads handle their own signals. Let the signal code
380 * know it'll be handled, so that they don't get converted to
381 * SIGKILL or just silently dropped.
382 */
383 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
384 recalc_sigpending();
385 spin_unlock_irq(¤t->sighand->siglock);
386 return 0;
387}
388
389EXPORT_SYMBOL(allow_signal);
390
391int disallow_signal(int sig)
392{
393 if (!valid_signal(sig) || sig < 1)
394 return -EINVAL;
395
396 spin_lock_irq(¤t->sighand->siglock);
397 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
398 recalc_sigpending();
399 spin_unlock_irq(¤t->sighand->siglock);
400 return 0;
401}
402
403EXPORT_SYMBOL(disallow_signal);
404
405/*
406 * Put all the gunge required to become a kernel thread without
407 * attached user resources in one place where it belongs.
408 */
409
410void daemonize(const char *name, ...)
411{
412 va_list args;
413 sigset_t blocked;
414
415 va_start(args, name);
416 vsnprintf(current->comm, sizeof(current->comm), name, args);
417 va_end(args);
418
419 /*
420 * If we were started as result of loading a module, close all of the
421 * user space pages. We don't need them, and if we didn't close them
422 * they would be locked into memory.
423 */
424 exit_mm(current);
425 /*
426 * We don't want to have TIF_FREEZE set if the system-wide hibernation
427 * or suspend transition begins right now.
428 */
429 current->flags |= (PF_NOFREEZE | PF_KTHREAD);
430
431 if (current->nsproxy != &init_nsproxy) {
432 get_nsproxy(&init_nsproxy);
433 switch_task_namespaces(current, &init_nsproxy);
434 }
435 set_special_pids(&init_struct_pid);
436 proc_clear_tty(current);
437
438 /* Block and flush all signals */
439 sigfillset(&blocked);
440 sigprocmask(SIG_BLOCK, &blocked, NULL);
441 flush_signals(current);
442
443 /* Become as one with the init task */
444
445 daemonize_fs_struct();
446 exit_files(current);
447 current->files = init_task.files;
448 atomic_inc(¤t->files->count);
449
450 reparent_to_kthreadd();
451}
452
453EXPORT_SYMBOL(daemonize);
454
455static void close_files(struct files_struct * files)
456{
457 int i, j;
458 struct fdtable *fdt;
459
460 j = 0;
461
462 /*
463 * It is safe to dereference the fd table without RCU or
464 * ->file_lock because this is the last reference to the
465 * files structure. But use RCU to shut RCU-lockdep up.
466 */
467 rcu_read_lock();
468 fdt = files_fdtable(files);
469 rcu_read_unlock();
470 for (;;) {
471 unsigned long set;
472 i = j * __NFDBITS;
473 if (i >= fdt->max_fds)
474 break;
475 set = fdt->open_fds->fds_bits[j++];
476 while (set) {
477 if (set & 1) {
478 struct file * file = xchg(&fdt->fd[i], NULL);
479 if (file) {
480 filp_close(file, files);
481 cond_resched();
482 }
483 }
484 i++;
485 set >>= 1;
486 }
487 }
488}
489
490struct files_struct *get_files_struct(struct task_struct *task)
491{
492 struct files_struct *files;
493
494 task_lock(task);
495 files = task->files;
496 if (files)
497 atomic_inc(&files->count);
498 task_unlock(task);
499
500 return files;
501}
502
503void put_files_struct(struct files_struct *files)
504{
505 struct fdtable *fdt;
506
507 if (atomic_dec_and_test(&files->count)) {
508 close_files(files);
509 /*
510 * Free the fd and fdset arrays if we expanded them.
511 * If the fdtable was embedded, pass files for freeing
512 * at the end of the RCU grace period. Otherwise,
513 * you can free files immediately.
514 */
515 rcu_read_lock();
516 fdt = files_fdtable(files);
517 if (fdt != &files->fdtab)
518 kmem_cache_free(files_cachep, files);
519 free_fdtable(fdt);
520 rcu_read_unlock();
521 }
522}
523
524void reset_files_struct(struct files_struct *files)
525{
526 struct task_struct *tsk = current;
527 struct files_struct *old;
528
529 old = tsk->files;
530 task_lock(tsk);
531 tsk->files = files;
532 task_unlock(tsk);
533 put_files_struct(old);
534}
535
536void exit_files(struct task_struct *tsk)
537{
538 struct files_struct * files = tsk->files;
539
540 if (files) {
541 task_lock(tsk);
542 tsk->files = NULL;
543 task_unlock(tsk);
544 put_files_struct(files);
545 }
546}
547
548#ifdef CONFIG_MM_OWNER
549/*
550 * A task is exiting. If it owned this mm, find a new owner for the mm.
551 */
552void mm_update_next_owner(struct mm_struct *mm)
553{
554 struct task_struct *c, *g, *p = current;
555
556retry:
557 /*
558 * If the exiting or execing task is not the owner, it's
559 * someone else's problem.
560 */
561 if (mm->owner != p)
562 return;
563 /*
564 * The current owner is exiting/execing and there are no other
565 * candidates. Do not leave the mm pointing to a possibly
566 * freed task structure.
567 */
568 if (atomic_read(&mm->mm_users) <= 1) {
569 mm->owner = NULL;
570 return;
571 }
572
573 read_lock(&tasklist_lock);
574 /*
575 * Search in the children
576 */
577 list_for_each_entry(c, &p->children, sibling) {
578 if (c->mm == mm)
579 goto assign_new_owner;
580 }
581
582 /*
583 * Search in the siblings
584 */
585 list_for_each_entry(c, &p->real_parent->children, sibling) {
586 if (c->mm == mm)
587 goto assign_new_owner;
588 }
589
590 /*
591 * Search through everything else. We should not get
592 * here often
593 */
594 do_each_thread(g, c) {
595 if (c->mm == mm)
596 goto assign_new_owner;
597 } while_each_thread(g, c);
598
599 read_unlock(&tasklist_lock);
600 /*
601 * We found no owner yet mm_users > 1: this implies that we are
602 * most likely racing with swapoff (try_to_unuse()) or /proc or
603 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
604 */
605 mm->owner = NULL;
606 return;
607
608assign_new_owner:
609 BUG_ON(c == p);
610 get_task_struct(c);
611 /*
612 * The task_lock protects c->mm from changing.
613 * We always want mm->owner->mm == mm
614 */
615 task_lock(c);
616 /*
617 * Delay read_unlock() till we have the task_lock()
618 * to ensure that c does not slip away underneath us
619 */
620 read_unlock(&tasklist_lock);
621 if (c->mm != mm) {
622 task_unlock(c);
623 put_task_struct(c);
624 goto retry;
625 }
626 mm->owner = c;
627 task_unlock(c);
628 put_task_struct(c);
629}
630#endif /* CONFIG_MM_OWNER */
631
632/*
633 * Turn us into a lazy TLB process if we
634 * aren't already..
635 */
636static void exit_mm(struct task_struct * tsk)
637{
638 struct mm_struct *mm = tsk->mm;
639 struct core_state *core_state;
640
641 mm_release(tsk, mm);
642 if (!mm)
643 return;
644 /*
645 * Serialize with any possible pending coredump.
646 * We must hold mmap_sem around checking core_state
647 * and clearing tsk->mm. The core-inducing thread
648 * will increment ->nr_threads for each thread in the
649 * group with ->mm != NULL.
650 */
651 down_read(&mm->mmap_sem);
652 core_state = mm->core_state;
653 if (core_state) {
654 struct core_thread self;
655 up_read(&mm->mmap_sem);
656
657 self.task = tsk;
658 self.next = xchg(&core_state->dumper.next, &self);
659 /*
660 * Implies mb(), the result of xchg() must be visible
661 * to core_state->dumper.
662 */
663 if (atomic_dec_and_test(&core_state->nr_threads))
664 complete(&core_state->startup);
665
666 for (;;) {
667 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
668 if (!self.task) /* see coredump_finish() */
669 break;
670 schedule();
671 }
672 __set_task_state(tsk, TASK_RUNNING);
673 down_read(&mm->mmap_sem);
674 }
675 atomic_inc(&mm->mm_count);
676 BUG_ON(mm != tsk->active_mm);
677 /* more a memory barrier than a real lock */
678 task_lock(tsk);
679 tsk->mm = NULL;
680 up_read(&mm->mmap_sem);
681 enter_lazy_tlb(mm, current);
682 /* We don't want this task to be frozen prematurely */
683 clear_freeze_flag(tsk);
684 if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
685 atomic_dec(&mm->oom_disable_count);
686 task_unlock(tsk);
687 mm_update_next_owner(mm);
688 mmput(mm);
689}
690
691/*
692 * When we die, we re-parent all our children.
693 * Try to give them to another thread in our thread
694 * group, and if no such member exists, give it to
695 * the child reaper process (ie "init") in our pid
696 * space.
697 */
698static struct task_struct *find_new_reaper(struct task_struct *father)
699 __releases(&tasklist_lock)
700 __acquires(&tasklist_lock)
701{
702 struct pid_namespace *pid_ns = task_active_pid_ns(father);
703 struct task_struct *thread;
704
705 thread = father;
706 while_each_thread(father, thread) {
707 if (thread->flags & PF_EXITING)
708 continue;
709 if (unlikely(pid_ns->child_reaper == father))
710 pid_ns->child_reaper = thread;
711 return thread;
712 }
713
714 if (unlikely(pid_ns->child_reaper == father)) {
715 write_unlock_irq(&tasklist_lock);
716 if (unlikely(pid_ns == &init_pid_ns))
717 panic("Attempted to kill init!");
718
719 zap_pid_ns_processes(pid_ns);
720 write_lock_irq(&tasklist_lock);
721 /*
722 * We can not clear ->child_reaper or leave it alone.
723 * There may by stealth EXIT_DEAD tasks on ->children,
724 * forget_original_parent() must move them somewhere.
725 */
726 pid_ns->child_reaper = init_pid_ns.child_reaper;
727 }
728
729 return pid_ns->child_reaper;
730}
731
732/*
733* Any that need to be release_task'd are put on the @dead list.
734 */
735static void reparent_leader(struct task_struct *father, struct task_struct *p,
736 struct list_head *dead)
737{
738 list_move_tail(&p->sibling, &p->real_parent->children);
739
740 if (p->exit_state == EXIT_DEAD)
741 return;
742 /*
743 * If this is a threaded reparent there is no need to
744 * notify anyone anything has happened.
745 */
746 if (same_thread_group(p->real_parent, father))
747 return;
748
749 /* We don't want people slaying init. */
750 p->exit_signal = SIGCHLD;
751
752 /* If it has exited notify the new parent about this child's death. */
753 if (!p->ptrace &&
754 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
755 if (do_notify_parent(p, p->exit_signal)) {
756 p->exit_state = EXIT_DEAD;
757 list_move_tail(&p->sibling, dead);
758 }
759 }
760
761 kill_orphaned_pgrp(p, father);
762}
763
764static void forget_original_parent(struct task_struct *father)
765{
766 struct task_struct *p, *n, *reaper;
767 LIST_HEAD(dead_children);
768
769 write_lock_irq(&tasklist_lock);
770 /*
771 * Note that exit_ptrace() and find_new_reaper() might
772 * drop tasklist_lock and reacquire it.
773 */
774 exit_ptrace(father);
775 reaper = find_new_reaper(father);
776
777 list_for_each_entry_safe(p, n, &father->children, sibling) {
778 struct task_struct *t = p;
779 do {
780 t->real_parent = reaper;
781 if (t->parent == father) {
782 BUG_ON(t->ptrace);
783 t->parent = t->real_parent;
784 }
785 if (t->pdeath_signal)
786 group_send_sig_info(t->pdeath_signal,
787 SEND_SIG_NOINFO, t);
788 } while_each_thread(p, t);
789 reparent_leader(father, p, &dead_children);
790 }
791 write_unlock_irq(&tasklist_lock);
792
793 BUG_ON(!list_empty(&father->children));
794
795 list_for_each_entry_safe(p, n, &dead_children, sibling) {
796 list_del_init(&p->sibling);
797 release_task(p);
798 }
799}
800
801/*
802 * Send signals to all our closest relatives so that they know
803 * to properly mourn us..
804 */
805static void exit_notify(struct task_struct *tsk, int group_dead)
806{
807 bool autoreap;
808
809 /*
810 * This does two things:
811 *
812 * A. Make init inherit all the child processes
813 * B. Check to see if any process groups have become orphaned
814 * as a result of our exiting, and if they have any stopped
815 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
816 */
817 forget_original_parent(tsk);
818 exit_task_namespaces(tsk);
819
820 write_lock_irq(&tasklist_lock);
821 if (group_dead)
822 kill_orphaned_pgrp(tsk->group_leader, NULL);
823
824 /* Let father know we died
825 *
826 * Thread signals are configurable, but you aren't going to use
827 * that to send signals to arbitrary processes.
828 * That stops right now.
829 *
830 * If the parent exec id doesn't match the exec id we saved
831 * when we started then we know the parent has changed security
832 * domain.
833 *
834 * If our self_exec id doesn't match our parent_exec_id then
835 * we have changed execution domain as these two values started
836 * the same after a fork.
837 */
838 if (thread_group_leader(tsk) && tsk->exit_signal != SIGCHLD &&
839 (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
840 tsk->self_exec_id != tsk->parent_exec_id))
841 tsk->exit_signal = SIGCHLD;
842
843 if (unlikely(tsk->ptrace)) {
844 int sig = thread_group_leader(tsk) &&
845 thread_group_empty(tsk) &&
846 !ptrace_reparented(tsk) ?
847 tsk->exit_signal : SIGCHLD;
848 autoreap = do_notify_parent(tsk, sig);
849 } else if (thread_group_leader(tsk)) {
850 autoreap = thread_group_empty(tsk) &&
851 do_notify_parent(tsk, tsk->exit_signal);
852 } else {
853 autoreap = true;
854 }
855
856 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
857
858 /* mt-exec, de_thread() is waiting for group leader */
859 if (unlikely(tsk->signal->notify_count < 0))
860 wake_up_process(tsk->signal->group_exit_task);
861 write_unlock_irq(&tasklist_lock);
862
863 /* If the process is dead, release it - nobody will wait for it */
864 if (autoreap)
865 release_task(tsk);
866}
867
868#ifdef CONFIG_DEBUG_STACK_USAGE
869static void check_stack_usage(void)
870{
871 static DEFINE_SPINLOCK(low_water_lock);
872 static int lowest_to_date = THREAD_SIZE;
873 unsigned long free;
874
875 free = stack_not_used(current);
876
877 if (free >= lowest_to_date)
878 return;
879
880 spin_lock(&low_water_lock);
881 if (free < lowest_to_date) {
882 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
883 "left\n",
884 current->comm, free);
885 lowest_to_date = free;
886 }
887 spin_unlock(&low_water_lock);
888}
889#else
890static inline void check_stack_usage(void) {}
891#endif
892
893NORET_TYPE void do_exit(long code)
894{
895 struct task_struct *tsk = current;
896 int group_dead;
897
898 profile_task_exit(tsk);
899
900 WARN_ON(blk_needs_flush_plug(tsk));
901
902 if (unlikely(in_interrupt()))
903 panic("Aiee, killing interrupt handler!");
904 if (unlikely(!tsk->pid))
905 panic("Attempted to kill the idle task!");
906
907 /*
908 * If do_exit is called because this processes oopsed, it's possible
909 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
910 * continuing. Amongst other possible reasons, this is to prevent
911 * mm_release()->clear_child_tid() from writing to a user-controlled
912 * kernel address.
913 */
914 set_fs(USER_DS);
915
916 ptrace_event(PTRACE_EVENT_EXIT, code);
917
918 validate_creds_for_do_exit(tsk);
919
920 /*
921 * We're taking recursive faults here in do_exit. Safest is to just
922 * leave this task alone and wait for reboot.
923 */
924 if (unlikely(tsk->flags & PF_EXITING)) {
925 printk(KERN_ALERT
926 "Fixing recursive fault but reboot is needed!\n");
927 /*
928 * We can do this unlocked here. The futex code uses
929 * this flag just to verify whether the pi state
930 * cleanup has been done or not. In the worst case it
931 * loops once more. We pretend that the cleanup was
932 * done as there is no way to return. Either the
933 * OWNER_DIED bit is set by now or we push the blocked
934 * task into the wait for ever nirwana as well.
935 */
936 tsk->flags |= PF_EXITPIDONE;
937 set_current_state(TASK_UNINTERRUPTIBLE);
938 schedule();
939 }
940
941 exit_irq_thread();
942
943 exit_signals(tsk); /* sets PF_EXITING */
944 /*
945 * tsk->flags are checked in the futex code to protect against
946 * an exiting task cleaning up the robust pi futexes.
947 */
948 smp_mb();
949 raw_spin_unlock_wait(&tsk->pi_lock);
950
951 if (unlikely(in_atomic()))
952 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
953 current->comm, task_pid_nr(current),
954 preempt_count());
955
956 acct_update_integrals(tsk);
957 /* sync mm's RSS info before statistics gathering */
958 if (tsk->mm)
959 sync_mm_rss(tsk, tsk->mm);
960 group_dead = atomic_dec_and_test(&tsk->signal->live);
961 if (group_dead) {
962 hrtimer_cancel(&tsk->signal->real_timer);
963 exit_itimers(tsk->signal);
964 if (tsk->mm)
965 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
966 }
967 acct_collect(code, group_dead);
968 if (group_dead)
969 tty_audit_exit();
970 if (unlikely(tsk->audit_context))
971 audit_free(tsk);
972
973 tsk->exit_code = code;
974 taskstats_exit(tsk, group_dead);
975
976 exit_mm(tsk);
977
978 if (group_dead)
979 acct_process();
980 trace_sched_process_exit(tsk);
981
982 exit_sem(tsk);
983 exit_shm(tsk);
984 exit_files(tsk);
985 exit_fs(tsk);
986 check_stack_usage();
987 exit_thread();
988
989 /*
990 * Flush inherited counters to the parent - before the parent
991 * gets woken up by child-exit notifications.
992 *
993 * because of cgroup mode, must be called before cgroup_exit()
994 */
995 perf_event_exit_task(tsk);
996
997 cgroup_exit(tsk, 1);
998
999 if (group_dead)
1000 disassociate_ctty(1);
1001
1002 module_put(task_thread_info(tsk)->exec_domain->module);
1003
1004 proc_exit_connector(tsk);
1005
1006 /*
1007 * FIXME: do that only when needed, using sched_exit tracepoint
1008 */
1009 ptrace_put_breakpoints(tsk);
1010
1011 exit_notify(tsk, group_dead);
1012#ifdef CONFIG_NUMA
1013 task_lock(tsk);
1014 mpol_put(tsk->mempolicy);
1015 tsk->mempolicy = NULL;
1016 task_unlock(tsk);
1017#endif
1018#ifdef CONFIG_FUTEX
1019 if (unlikely(current->pi_state_cache))
1020 kfree(current->pi_state_cache);
1021#endif
1022 /*
1023 * Make sure we are holding no locks:
1024 */
1025 debug_check_no_locks_held(tsk);
1026 /*
1027 * We can do this unlocked here. The futex code uses this flag
1028 * just to verify whether the pi state cleanup has been done
1029 * or not. In the worst case it loops once more.
1030 */
1031 tsk->flags |= PF_EXITPIDONE;
1032
1033 if (tsk->io_context)
1034 exit_io_context(tsk);
1035
1036 if (tsk->splice_pipe)
1037 __free_pipe_info(tsk->splice_pipe);
1038
1039 validate_creds_for_do_exit(tsk);
1040
1041 preempt_disable();
1042 exit_rcu();
1043 /* causes final put_task_struct in finish_task_switch(). */
1044 tsk->state = TASK_DEAD;
1045 schedule();
1046 BUG();
1047 /* Avoid "noreturn function does return". */
1048 for (;;)
1049 cpu_relax(); /* For when BUG is null */
1050}
1051
1052EXPORT_SYMBOL_GPL(do_exit);
1053
1054NORET_TYPE void complete_and_exit(struct completion *comp, long code)
1055{
1056 if (comp)
1057 complete(comp);
1058
1059 do_exit(code);
1060}
1061
1062EXPORT_SYMBOL(complete_and_exit);
1063
1064SYSCALL_DEFINE1(exit, int, error_code)
1065{
1066 do_exit((error_code&0xff)<<8);
1067}
1068
1069/*
1070 * Take down every thread in the group. This is called by fatal signals
1071 * as well as by sys_exit_group (below).
1072 */
1073NORET_TYPE void
1074do_group_exit(int exit_code)
1075{
1076 struct signal_struct *sig = current->signal;
1077
1078 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1079
1080 if (signal_group_exit(sig))
1081 exit_code = sig->group_exit_code;
1082 else if (!thread_group_empty(current)) {
1083 struct sighand_struct *const sighand = current->sighand;
1084 spin_lock_irq(&sighand->siglock);
1085 if (signal_group_exit(sig))
1086 /* Another thread got here before we took the lock. */
1087 exit_code = sig->group_exit_code;
1088 else {
1089 sig->group_exit_code = exit_code;
1090 sig->flags = SIGNAL_GROUP_EXIT;
1091 zap_other_threads(current);
1092 }
1093 spin_unlock_irq(&sighand->siglock);
1094 }
1095
1096 do_exit(exit_code);
1097 /* NOTREACHED */
1098}
1099
1100/*
1101 * this kills every thread in the thread group. Note that any externally
1102 * wait4()-ing process will get the correct exit code - even if this
1103 * thread is not the thread group leader.
1104 */
1105SYSCALL_DEFINE1(exit_group, int, error_code)
1106{
1107 do_group_exit((error_code & 0xff) << 8);
1108 /* NOTREACHED */
1109 return 0;
1110}
1111
1112struct wait_opts {
1113 enum pid_type wo_type;
1114 int wo_flags;
1115 struct pid *wo_pid;
1116
1117 struct siginfo __user *wo_info;
1118 int __user *wo_stat;
1119 struct rusage __user *wo_rusage;
1120
1121 wait_queue_t child_wait;
1122 int notask_error;
1123};
1124
1125static inline
1126struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
1127{
1128 if (type != PIDTYPE_PID)
1129 task = task->group_leader;
1130 return task->pids[type].pid;
1131}
1132
1133static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
1134{
1135 return wo->wo_type == PIDTYPE_MAX ||
1136 task_pid_type(p, wo->wo_type) == wo->wo_pid;
1137}
1138
1139static int eligible_child(struct wait_opts *wo, struct task_struct *p)
1140{
1141 if (!eligible_pid(wo, p))
1142 return 0;
1143 /* Wait for all children (clone and not) if __WALL is set;
1144 * otherwise, wait for clone children *only* if __WCLONE is
1145 * set; otherwise, wait for non-clone children *only*. (Note:
1146 * A "clone" child here is one that reports to its parent
1147 * using a signal other than SIGCHLD.) */
1148 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
1149 && !(wo->wo_flags & __WALL))
1150 return 0;
1151
1152 return 1;
1153}
1154
1155static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
1156 pid_t pid, uid_t uid, int why, int status)
1157{
1158 struct siginfo __user *infop;
1159 int retval = wo->wo_rusage
1160 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1161
1162 put_task_struct(p);
1163 infop = wo->wo_info;
1164 if (infop) {
1165 if (!retval)
1166 retval = put_user(SIGCHLD, &infop->si_signo);
1167 if (!retval)
1168 retval = put_user(0, &infop->si_errno);
1169 if (!retval)
1170 retval = put_user((short)why, &infop->si_code);
1171 if (!retval)
1172 retval = put_user(pid, &infop->si_pid);
1173 if (!retval)
1174 retval = put_user(uid, &infop->si_uid);
1175 if (!retval)
1176 retval = put_user(status, &infop->si_status);
1177 }
1178 if (!retval)
1179 retval = pid;
1180 return retval;
1181}
1182
1183/*
1184 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1185 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1186 * the lock and this task is uninteresting. If we return nonzero, we have
1187 * released the lock and the system call should return.
1188 */
1189static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1190{
1191 unsigned long state;
1192 int retval, status, traced;
1193 pid_t pid = task_pid_vnr(p);
1194 uid_t uid = __task_cred(p)->uid;
1195 struct siginfo __user *infop;
1196
1197 if (!likely(wo->wo_flags & WEXITED))
1198 return 0;
1199
1200 if (unlikely(wo->wo_flags & WNOWAIT)) {
1201 int exit_code = p->exit_code;
1202 int why;
1203
1204 get_task_struct(p);
1205 read_unlock(&tasklist_lock);
1206 if ((exit_code & 0x7f) == 0) {
1207 why = CLD_EXITED;
1208 status = exit_code >> 8;
1209 } else {
1210 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1211 status = exit_code & 0x7f;
1212 }
1213 return wait_noreap_copyout(wo, p, pid, uid, why, status);
1214 }
1215
1216 /*
1217 * Try to move the task's state to DEAD
1218 * only one thread is allowed to do this:
1219 */
1220 state = xchg(&p->exit_state, EXIT_DEAD);
1221 if (state != EXIT_ZOMBIE) {
1222 BUG_ON(state != EXIT_DEAD);
1223 return 0;
1224 }
1225
1226 traced = ptrace_reparented(p);
1227 /*
1228 * It can be ptraced but not reparented, check
1229 * thread_group_leader() to filter out sub-threads.
1230 */
1231 if (likely(!traced) && thread_group_leader(p)) {
1232 struct signal_struct *psig;
1233 struct signal_struct *sig;
1234 unsigned long maxrss;
1235 cputime_t tgutime, tgstime;
1236
1237 /*
1238 * The resource counters for the group leader are in its
1239 * own task_struct. Those for dead threads in the group
1240 * are in its signal_struct, as are those for the child
1241 * processes it has previously reaped. All these
1242 * accumulate in the parent's signal_struct c* fields.
1243 *
1244 * We don't bother to take a lock here to protect these
1245 * p->signal fields, because they are only touched by
1246 * __exit_signal, which runs with tasklist_lock
1247 * write-locked anyway, and so is excluded here. We do
1248 * need to protect the access to parent->signal fields,
1249 * as other threads in the parent group can be right
1250 * here reaping other children at the same time.
1251 *
1252 * We use thread_group_times() to get times for the thread
1253 * group, which consolidates times for all threads in the
1254 * group including the group leader.
1255 */
1256 thread_group_times(p, &tgutime, &tgstime);
1257 spin_lock_irq(&p->real_parent->sighand->siglock);
1258 psig = p->real_parent->signal;
1259 sig = p->signal;
1260 psig->cutime =
1261 cputime_add(psig->cutime,
1262 cputime_add(tgutime,
1263 sig->cutime));
1264 psig->cstime =
1265 cputime_add(psig->cstime,
1266 cputime_add(tgstime,
1267 sig->cstime));
1268 psig->cgtime =
1269 cputime_add(psig->cgtime,
1270 cputime_add(p->gtime,
1271 cputime_add(sig->gtime,
1272 sig->cgtime)));
1273 psig->cmin_flt +=
1274 p->min_flt + sig->min_flt + sig->cmin_flt;
1275 psig->cmaj_flt +=
1276 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1277 psig->cnvcsw +=
1278 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1279 psig->cnivcsw +=
1280 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1281 psig->cinblock +=
1282 task_io_get_inblock(p) +
1283 sig->inblock + sig->cinblock;
1284 psig->coublock +=
1285 task_io_get_oublock(p) +
1286 sig->oublock + sig->coublock;
1287 maxrss = max(sig->maxrss, sig->cmaxrss);
1288 if (psig->cmaxrss < maxrss)
1289 psig->cmaxrss = maxrss;
1290 task_io_accounting_add(&psig->ioac, &p->ioac);
1291 task_io_accounting_add(&psig->ioac, &sig->ioac);
1292 spin_unlock_irq(&p->real_parent->sighand->siglock);
1293 }
1294
1295 /*
1296 * Now we are sure this task is interesting, and no other
1297 * thread can reap it because we set its state to EXIT_DEAD.
1298 */
1299 read_unlock(&tasklist_lock);
1300
1301 retval = wo->wo_rusage
1302 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1303 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1304 ? p->signal->group_exit_code : p->exit_code;
1305 if (!retval && wo->wo_stat)
1306 retval = put_user(status, wo->wo_stat);
1307
1308 infop = wo->wo_info;
1309 if (!retval && infop)
1310 retval = put_user(SIGCHLD, &infop->si_signo);
1311 if (!retval && infop)
1312 retval = put_user(0, &infop->si_errno);
1313 if (!retval && infop) {
1314 int why;
1315
1316 if ((status & 0x7f) == 0) {
1317 why = CLD_EXITED;
1318 status >>= 8;
1319 } else {
1320 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1321 status &= 0x7f;
1322 }
1323 retval = put_user((short)why, &infop->si_code);
1324 if (!retval)
1325 retval = put_user(status, &infop->si_status);
1326 }
1327 if (!retval && infop)
1328 retval = put_user(pid, &infop->si_pid);
1329 if (!retval && infop)
1330 retval = put_user(uid, &infop->si_uid);
1331 if (!retval)
1332 retval = pid;
1333
1334 if (traced) {
1335 write_lock_irq(&tasklist_lock);
1336 /* We dropped tasklist, ptracer could die and untrace */
1337 ptrace_unlink(p);
1338 /*
1339 * If this is not a sub-thread, notify the parent.
1340 * If parent wants a zombie, don't release it now.
1341 */
1342 if (thread_group_leader(p) &&
1343 !do_notify_parent(p, p->exit_signal)) {
1344 p->exit_state = EXIT_ZOMBIE;
1345 p = NULL;
1346 }
1347 write_unlock_irq(&tasklist_lock);
1348 }
1349 if (p != NULL)
1350 release_task(p);
1351
1352 return retval;
1353}
1354
1355static int *task_stopped_code(struct task_struct *p, bool ptrace)
1356{
1357 if (ptrace) {
1358 if (task_is_stopped_or_traced(p) &&
1359 !(p->jobctl & JOBCTL_LISTENING))
1360 return &p->exit_code;
1361 } else {
1362 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1363 return &p->signal->group_exit_code;
1364 }
1365 return NULL;
1366}
1367
1368/**
1369 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1370 * @wo: wait options
1371 * @ptrace: is the wait for ptrace
1372 * @p: task to wait for
1373 *
1374 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1375 *
1376 * CONTEXT:
1377 * read_lock(&tasklist_lock), which is released if return value is
1378 * non-zero. Also, grabs and releases @p->sighand->siglock.
1379 *
1380 * RETURNS:
1381 * 0 if wait condition didn't exist and search for other wait conditions
1382 * should continue. Non-zero return, -errno on failure and @p's pid on
1383 * success, implies that tasklist_lock is released and wait condition
1384 * search should terminate.
1385 */
1386static int wait_task_stopped(struct wait_opts *wo,
1387 int ptrace, struct task_struct *p)
1388{
1389 struct siginfo __user *infop;
1390 int retval, exit_code, *p_code, why;
1391 uid_t uid = 0; /* unneeded, required by compiler */
1392 pid_t pid;
1393
1394 /*
1395 * Traditionally we see ptrace'd stopped tasks regardless of options.
1396 */
1397 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1398 return 0;
1399
1400 if (!task_stopped_code(p, ptrace))
1401 return 0;
1402
1403 exit_code = 0;
1404 spin_lock_irq(&p->sighand->siglock);
1405
1406 p_code = task_stopped_code(p, ptrace);
1407 if (unlikely(!p_code))
1408 goto unlock_sig;
1409
1410 exit_code = *p_code;
1411 if (!exit_code)
1412 goto unlock_sig;
1413
1414 if (!unlikely(wo->wo_flags & WNOWAIT))
1415 *p_code = 0;
1416
1417 uid = task_uid(p);
1418unlock_sig:
1419 spin_unlock_irq(&p->sighand->siglock);
1420 if (!exit_code)
1421 return 0;
1422
1423 /*
1424 * Now we are pretty sure this task is interesting.
1425 * Make sure it doesn't get reaped out from under us while we
1426 * give up the lock and then examine it below. We don't want to
1427 * keep holding onto the tasklist_lock while we call getrusage and
1428 * possibly take page faults for user memory.
1429 */
1430 get_task_struct(p);
1431 pid = task_pid_vnr(p);
1432 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1433 read_unlock(&tasklist_lock);
1434
1435 if (unlikely(wo->wo_flags & WNOWAIT))
1436 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
1437
1438 retval = wo->wo_rusage
1439 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1440 if (!retval && wo->wo_stat)
1441 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
1442
1443 infop = wo->wo_info;
1444 if (!retval && infop)
1445 retval = put_user(SIGCHLD, &infop->si_signo);
1446 if (!retval && infop)
1447 retval = put_user(0, &infop->si_errno);
1448 if (!retval && infop)
1449 retval = put_user((short)why, &infop->si_code);
1450 if (!retval && infop)
1451 retval = put_user(exit_code, &infop->si_status);
1452 if (!retval && infop)
1453 retval = put_user(pid, &infop->si_pid);
1454 if (!retval && infop)
1455 retval = put_user(uid, &infop->si_uid);
1456 if (!retval)
1457 retval = pid;
1458 put_task_struct(p);
1459
1460 BUG_ON(!retval);
1461 return retval;
1462}
1463
1464/*
1465 * Handle do_wait work for one task in a live, non-stopped state.
1466 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1467 * the lock and this task is uninteresting. If we return nonzero, we have
1468 * released the lock and the system call should return.
1469 */
1470static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1471{
1472 int retval;
1473 pid_t pid;
1474 uid_t uid;
1475
1476 if (!unlikely(wo->wo_flags & WCONTINUED))
1477 return 0;
1478
1479 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1480 return 0;
1481
1482 spin_lock_irq(&p->sighand->siglock);
1483 /* Re-check with the lock held. */
1484 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1485 spin_unlock_irq(&p->sighand->siglock);
1486 return 0;
1487 }
1488 if (!unlikely(wo->wo_flags & WNOWAIT))
1489 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1490 uid = task_uid(p);
1491 spin_unlock_irq(&p->sighand->siglock);
1492
1493 pid = task_pid_vnr(p);
1494 get_task_struct(p);
1495 read_unlock(&tasklist_lock);
1496
1497 if (!wo->wo_info) {
1498 retval = wo->wo_rusage
1499 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1500 put_task_struct(p);
1501 if (!retval && wo->wo_stat)
1502 retval = put_user(0xffff, wo->wo_stat);
1503 if (!retval)
1504 retval = pid;
1505 } else {
1506 retval = wait_noreap_copyout(wo, p, pid, uid,
1507 CLD_CONTINUED, SIGCONT);
1508 BUG_ON(retval == 0);
1509 }
1510
1511 return retval;
1512}
1513
1514/*
1515 * Consider @p for a wait by @parent.
1516 *
1517 * -ECHILD should be in ->notask_error before the first call.
1518 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1519 * Returns zero if the search for a child should continue;
1520 * then ->notask_error is 0 if @p is an eligible child,
1521 * or another error from security_task_wait(), or still -ECHILD.
1522 */
1523static int wait_consider_task(struct wait_opts *wo, int ptrace,
1524 struct task_struct *p)
1525{
1526 int ret = eligible_child(wo, p);
1527 if (!ret)
1528 return ret;
1529
1530 ret = security_task_wait(p);
1531 if (unlikely(ret < 0)) {
1532 /*
1533 * If we have not yet seen any eligible child,
1534 * then let this error code replace -ECHILD.
1535 * A permission error will give the user a clue
1536 * to look for security policy problems, rather
1537 * than for mysterious wait bugs.
1538 */
1539 if (wo->notask_error)
1540 wo->notask_error = ret;
1541 return 0;
1542 }
1543
1544 /* dead body doesn't have much to contribute */
1545 if (p->exit_state == EXIT_DEAD)
1546 return 0;
1547
1548 /* slay zombie? */
1549 if (p->exit_state == EXIT_ZOMBIE) {
1550 /*
1551 * A zombie ptracee is only visible to its ptracer.
1552 * Notification and reaping will be cascaded to the real
1553 * parent when the ptracer detaches.
1554 */
1555 if (likely(!ptrace) && unlikely(p->ptrace)) {
1556 /* it will become visible, clear notask_error */
1557 wo->notask_error = 0;
1558 return 0;
1559 }
1560
1561 /* we don't reap group leaders with subthreads */
1562 if (!delay_group_leader(p))
1563 return wait_task_zombie(wo, p);
1564
1565 /*
1566 * Allow access to stopped/continued state via zombie by
1567 * falling through. Clearing of notask_error is complex.
1568 *
1569 * When !@ptrace:
1570 *
1571 * If WEXITED is set, notask_error should naturally be
1572 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1573 * so, if there are live subthreads, there are events to
1574 * wait for. If all subthreads are dead, it's still safe
1575 * to clear - this function will be called again in finite
1576 * amount time once all the subthreads are released and
1577 * will then return without clearing.
1578 *
1579 * When @ptrace:
1580 *
1581 * Stopped state is per-task and thus can't change once the
1582 * target task dies. Only continued and exited can happen.
1583 * Clear notask_error if WCONTINUED | WEXITED.
1584 */
1585 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1586 wo->notask_error = 0;
1587 } else {
1588 /*
1589 * If @p is ptraced by a task in its real parent's group,
1590 * hide group stop/continued state when looking at @p as
1591 * the real parent; otherwise, a single stop can be
1592 * reported twice as group and ptrace stops.
1593 *
1594 * If a ptracer wants to distinguish the two events for its
1595 * own children, it should create a separate process which
1596 * takes the role of real parent.
1597 */
1598 if (likely(!ptrace) && p->ptrace && !ptrace_reparented(p))
1599 return 0;
1600
1601 /*
1602 * @p is alive and it's gonna stop, continue or exit, so
1603 * there always is something to wait for.
1604 */
1605 wo->notask_error = 0;
1606 }
1607
1608 /*
1609 * Wait for stopped. Depending on @ptrace, different stopped state
1610 * is used and the two don't interact with each other.
1611 */
1612 ret = wait_task_stopped(wo, ptrace, p);
1613 if (ret)
1614 return ret;
1615
1616 /*
1617 * Wait for continued. There's only one continued state and the
1618 * ptracer can consume it which can confuse the real parent. Don't
1619 * use WCONTINUED from ptracer. You don't need or want it.
1620 */
1621 return wait_task_continued(wo, p);
1622}
1623
1624/*
1625 * Do the work of do_wait() for one thread in the group, @tsk.
1626 *
1627 * -ECHILD should be in ->notask_error before the first call.
1628 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1629 * Returns zero if the search for a child should continue; then
1630 * ->notask_error is 0 if there were any eligible children,
1631 * or another error from security_task_wait(), or still -ECHILD.
1632 */
1633static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1634{
1635 struct task_struct *p;
1636
1637 list_for_each_entry(p, &tsk->children, sibling) {
1638 int ret = wait_consider_task(wo, 0, p);
1639 if (ret)
1640 return ret;
1641 }
1642
1643 return 0;
1644}
1645
1646static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1647{
1648 struct task_struct *p;
1649
1650 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1651 int ret = wait_consider_task(wo, 1, p);
1652 if (ret)
1653 return ret;
1654 }
1655
1656 return 0;
1657}
1658
1659static int child_wait_callback(wait_queue_t *wait, unsigned mode,
1660 int sync, void *key)
1661{
1662 struct wait_opts *wo = container_of(wait, struct wait_opts,
1663 child_wait);
1664 struct task_struct *p = key;
1665
1666 if (!eligible_pid(wo, p))
1667 return 0;
1668
1669 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1670 return 0;
1671
1672 return default_wake_function(wait, mode, sync, key);
1673}
1674
1675void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1676{
1677 __wake_up_sync_key(&parent->signal->wait_chldexit,
1678 TASK_INTERRUPTIBLE, 1, p);
1679}
1680
1681static long do_wait(struct wait_opts *wo)
1682{
1683 struct task_struct *tsk;
1684 int retval;
1685
1686 trace_sched_process_wait(wo->wo_pid);
1687
1688 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1689 wo->child_wait.private = current;
1690 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1691repeat:
1692 /*
1693 * If there is nothing that can match our critiera just get out.
1694 * We will clear ->notask_error to zero if we see any child that
1695 * might later match our criteria, even if we are not able to reap
1696 * it yet.
1697 */
1698 wo->notask_error = -ECHILD;
1699 if ((wo->wo_type < PIDTYPE_MAX) &&
1700 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1701 goto notask;
1702
1703 set_current_state(TASK_INTERRUPTIBLE);
1704 read_lock(&tasklist_lock);
1705 tsk = current;
1706 do {
1707 retval = do_wait_thread(wo, tsk);
1708 if (retval)
1709 goto end;
1710
1711 retval = ptrace_do_wait(wo, tsk);
1712 if (retval)
1713 goto end;
1714
1715 if (wo->wo_flags & __WNOTHREAD)
1716 break;
1717 } while_each_thread(current, tsk);
1718 read_unlock(&tasklist_lock);
1719
1720notask:
1721 retval = wo->notask_error;
1722 if (!retval && !(wo->wo_flags & WNOHANG)) {
1723 retval = -ERESTARTSYS;
1724 if (!signal_pending(current)) {
1725 schedule();
1726 goto repeat;
1727 }
1728 }
1729end:
1730 __set_current_state(TASK_RUNNING);
1731 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1732 return retval;
1733}
1734
1735SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1736 infop, int, options, struct rusage __user *, ru)
1737{
1738 struct wait_opts wo;
1739 struct pid *pid = NULL;
1740 enum pid_type type;
1741 long ret;
1742
1743 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1744 return -EINVAL;
1745 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1746 return -EINVAL;
1747
1748 switch (which) {
1749 case P_ALL:
1750 type = PIDTYPE_MAX;
1751 break;
1752 case P_PID:
1753 type = PIDTYPE_PID;
1754 if (upid <= 0)
1755 return -EINVAL;
1756 break;
1757 case P_PGID:
1758 type = PIDTYPE_PGID;
1759 if (upid <= 0)
1760 return -EINVAL;
1761 break;
1762 default:
1763 return -EINVAL;
1764 }
1765
1766 if (type < PIDTYPE_MAX)
1767 pid = find_get_pid(upid);
1768
1769 wo.wo_type = type;
1770 wo.wo_pid = pid;
1771 wo.wo_flags = options;
1772 wo.wo_info = infop;
1773 wo.wo_stat = NULL;
1774 wo.wo_rusage = ru;
1775 ret = do_wait(&wo);
1776
1777 if (ret > 0) {
1778 ret = 0;
1779 } else if (infop) {
1780 /*
1781 * For a WNOHANG return, clear out all the fields
1782 * we would set so the user can easily tell the
1783 * difference.
1784 */
1785 if (!ret)
1786 ret = put_user(0, &infop->si_signo);
1787 if (!ret)
1788 ret = put_user(0, &infop->si_errno);
1789 if (!ret)
1790 ret = put_user(0, &infop->si_code);
1791 if (!ret)
1792 ret = put_user(0, &infop->si_pid);
1793 if (!ret)
1794 ret = put_user(0, &infop->si_uid);
1795 if (!ret)
1796 ret = put_user(0, &infop->si_status);
1797 }
1798
1799 put_pid(pid);
1800
1801 /* avoid REGPARM breakage on x86: */
1802 asmlinkage_protect(5, ret, which, upid, infop, options, ru);
1803 return ret;
1804}
1805
1806SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1807 int, options, struct rusage __user *, ru)
1808{
1809 struct wait_opts wo;
1810 struct pid *pid = NULL;
1811 enum pid_type type;
1812 long ret;
1813
1814 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1815 __WNOTHREAD|__WCLONE|__WALL))
1816 return -EINVAL;
1817
1818 if (upid == -1)
1819 type = PIDTYPE_MAX;
1820 else if (upid < 0) {
1821 type = PIDTYPE_PGID;
1822 pid = find_get_pid(-upid);
1823 } else if (upid == 0) {
1824 type = PIDTYPE_PGID;
1825 pid = get_task_pid(current, PIDTYPE_PGID);
1826 } else /* upid > 0 */ {
1827 type = PIDTYPE_PID;
1828 pid = find_get_pid(upid);
1829 }
1830
1831 wo.wo_type = type;
1832 wo.wo_pid = pid;
1833 wo.wo_flags = options | WEXITED;
1834 wo.wo_info = NULL;
1835 wo.wo_stat = stat_addr;
1836 wo.wo_rusage = ru;
1837 ret = do_wait(&wo);
1838 put_pid(pid);
1839
1840 /* avoid REGPARM breakage on x86: */
1841 asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
1842 return ret;
1843}
1844
1845#ifdef __ARCH_WANT_SYS_WAITPID
1846
1847/*
1848 * sys_waitpid() remains for compatibility. waitpid() should be
1849 * implemented by calling sys_wait4() from libc.a.
1850 */
1851SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1852{
1853 return sys_wait4(pid, stat_addr, options, NULL);
1854}
1855
1856#endif