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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/exit.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8#include <linux/mm.h>
9#include <linux/slab.h>
10#include <linux/sched/autogroup.h>
11#include <linux/sched/mm.h>
12#include <linux/sched/stat.h>
13#include <linux/sched/task.h>
14#include <linux/sched/task_stack.h>
15#include <linux/sched/cputime.h>
16#include <linux/interrupt.h>
17#include <linux/module.h>
18#include <linux/capability.h>
19#include <linux/completion.h>
20#include <linux/personality.h>
21#include <linux/tty.h>
22#include <linux/iocontext.h>
23#include <linux/key.h>
24#include <linux/cpu.h>
25#include <linux/acct.h>
26#include <linux/tsacct_kern.h>
27#include <linux/file.h>
28#include <linux/fdtable.h>
29#include <linux/freezer.h>
30#include <linux/binfmts.h>
31#include <linux/nsproxy.h>
32#include <linux/pid_namespace.h>
33#include <linux/ptrace.h>
34#include <linux/profile.h>
35#include <linux/mount.h>
36#include <linux/proc_fs.h>
37#include <linux/kthread.h>
38#include <linux/mempolicy.h>
39#include <linux/taskstats_kern.h>
40#include <linux/delayacct.h>
41#include <linux/cgroup.h>
42#include <linux/syscalls.h>
43#include <linux/signal.h>
44#include <linux/posix-timers.h>
45#include <linux/cn_proc.h>
46#include <linux/mutex.h>
47#include <linux/futex.h>
48#include <linux/pipe_fs_i.h>
49#include <linux/audit.h> /* for audit_free() */
50#include <linux/resource.h>
51#include <linux/blkdev.h>
52#include <linux/task_io_accounting_ops.h>
53#include <linux/tracehook.h>
54#include <linux/fs_struct.h>
55#include <linux/init_task.h>
56#include <linux/perf_event.h>
57#include <trace/events/sched.h>
58#include <linux/hw_breakpoint.h>
59#include <linux/oom.h>
60#include <linux/writeback.h>
61#include <linux/shm.h>
62#include <linux/kcov.h>
63#include <linux/random.h>
64#include <linux/rcuwait.h>
65#include <linux/compat.h>
66
67#include <linux/uaccess.h>
68#include <asm/unistd.h>
69#include <asm/pgtable.h>
70#include <asm/mmu_context.h>
71
72static void __unhash_process(struct task_struct *p, bool group_dead)
73{
74 nr_threads--;
75 detach_pid(p, PIDTYPE_PID);
76 if (group_dead) {
77 detach_pid(p, PIDTYPE_TGID);
78 detach_pid(p, PIDTYPE_PGID);
79 detach_pid(p, PIDTYPE_SID);
80
81 list_del_rcu(&p->tasks);
82 list_del_init(&p->sibling);
83 __this_cpu_dec(process_counts);
84 }
85 list_del_rcu(&p->thread_group);
86 list_del_rcu(&p->thread_node);
87}
88
89/*
90 * This function expects the tasklist_lock write-locked.
91 */
92static void __exit_signal(struct task_struct *tsk)
93{
94 struct signal_struct *sig = tsk->signal;
95 bool group_dead = thread_group_leader(tsk);
96 struct sighand_struct *sighand;
97 struct tty_struct *uninitialized_var(tty);
98 u64 utime, stime;
99
100 sighand = rcu_dereference_check(tsk->sighand,
101 lockdep_tasklist_lock_is_held());
102 spin_lock(&sighand->siglock);
103
104#ifdef CONFIG_POSIX_TIMERS
105 posix_cpu_timers_exit(tsk);
106 if (group_dead) {
107 posix_cpu_timers_exit_group(tsk);
108 } else {
109 /*
110 * This can only happen if the caller is de_thread().
111 * FIXME: this is the temporary hack, we should teach
112 * posix-cpu-timers to handle this case correctly.
113 */
114 if (unlikely(has_group_leader_pid(tsk)))
115 posix_cpu_timers_exit_group(tsk);
116 }
117#endif
118
119 if (group_dead) {
120 tty = sig->tty;
121 sig->tty = NULL;
122 } else {
123 /*
124 * If there is any task waiting for the group exit
125 * then notify it:
126 */
127 if (sig->notify_count > 0 && !--sig->notify_count)
128 wake_up_process(sig->group_exit_task);
129
130 if (tsk == sig->curr_target)
131 sig->curr_target = next_thread(tsk);
132 }
133
134 add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
135 sizeof(unsigned long long));
136
137 /*
138 * Accumulate here the counters for all threads as they die. We could
139 * skip the group leader because it is the last user of signal_struct,
140 * but we want to avoid the race with thread_group_cputime() which can
141 * see the empty ->thread_head list.
142 */
143 task_cputime(tsk, &utime, &stime);
144 write_seqlock(&sig->stats_lock);
145 sig->utime += utime;
146 sig->stime += stime;
147 sig->gtime += task_gtime(tsk);
148 sig->min_flt += tsk->min_flt;
149 sig->maj_flt += tsk->maj_flt;
150 sig->nvcsw += tsk->nvcsw;
151 sig->nivcsw += tsk->nivcsw;
152 sig->inblock += task_io_get_inblock(tsk);
153 sig->oublock += task_io_get_oublock(tsk);
154 task_io_accounting_add(&sig->ioac, &tsk->ioac);
155 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
156 sig->nr_threads--;
157 __unhash_process(tsk, group_dead);
158 write_sequnlock(&sig->stats_lock);
159
160 /*
161 * Do this under ->siglock, we can race with another thread
162 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
163 */
164 flush_sigqueue(&tsk->pending);
165 tsk->sighand = NULL;
166 spin_unlock(&sighand->siglock);
167
168 __cleanup_sighand(sighand);
169 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
170 if (group_dead) {
171 flush_sigqueue(&sig->shared_pending);
172 tty_kref_put(tty);
173 }
174}
175
176static void delayed_put_task_struct(struct rcu_head *rhp)
177{
178 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
179
180 perf_event_delayed_put(tsk);
181 trace_sched_process_free(tsk);
182 put_task_struct(tsk);
183}
184
185void put_task_struct_rcu_user(struct task_struct *task)
186{
187 if (refcount_dec_and_test(&task->rcu_users))
188 call_rcu(&task->rcu, delayed_put_task_struct);
189}
190
191void release_task(struct task_struct *p)
192{
193 struct task_struct *leader;
194 int zap_leader;
195repeat:
196 /* don't need to get the RCU readlock here - the process is dead and
197 * can't be modifying its own credentials. But shut RCU-lockdep up */
198 rcu_read_lock();
199 atomic_dec(&__task_cred(p)->user->processes);
200 rcu_read_unlock();
201
202 proc_flush_task(p);
203 cgroup_release(p);
204
205 write_lock_irq(&tasklist_lock);
206 ptrace_release_task(p);
207 __exit_signal(p);
208
209 /*
210 * If we are the last non-leader member of the thread
211 * group, and the leader is zombie, then notify the
212 * group leader's parent process. (if it wants notification.)
213 */
214 zap_leader = 0;
215 leader = p->group_leader;
216 if (leader != p && thread_group_empty(leader)
217 && leader->exit_state == EXIT_ZOMBIE) {
218 /*
219 * If we were the last child thread and the leader has
220 * exited already, and the leader's parent ignores SIGCHLD,
221 * then we are the one who should release the leader.
222 */
223 zap_leader = do_notify_parent(leader, leader->exit_signal);
224 if (zap_leader)
225 leader->exit_state = EXIT_DEAD;
226 }
227
228 write_unlock_irq(&tasklist_lock);
229 release_thread(p);
230 put_task_struct_rcu_user(p);
231
232 p = leader;
233 if (unlikely(zap_leader))
234 goto repeat;
235}
236
237void rcuwait_wake_up(struct rcuwait *w)
238{
239 struct task_struct *task;
240
241 rcu_read_lock();
242
243 /*
244 * Order condition vs @task, such that everything prior to the load
245 * of @task is visible. This is the condition as to why the user called
246 * rcuwait_trywake() in the first place. Pairs with set_current_state()
247 * barrier (A) in rcuwait_wait_event().
248 *
249 * WAIT WAKE
250 * [S] tsk = current [S] cond = true
251 * MB (A) MB (B)
252 * [L] cond [L] tsk
253 */
254 smp_mb(); /* (B) */
255
256 task = rcu_dereference(w->task);
257 if (task)
258 wake_up_process(task);
259 rcu_read_unlock();
260}
261
262/*
263 * Determine if a process group is "orphaned", according to the POSIX
264 * definition in 2.2.2.52. Orphaned process groups are not to be affected
265 * by terminal-generated stop signals. Newly orphaned process groups are
266 * to receive a SIGHUP and a SIGCONT.
267 *
268 * "I ask you, have you ever known what it is to be an orphan?"
269 */
270static int will_become_orphaned_pgrp(struct pid *pgrp,
271 struct task_struct *ignored_task)
272{
273 struct task_struct *p;
274
275 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
276 if ((p == ignored_task) ||
277 (p->exit_state && thread_group_empty(p)) ||
278 is_global_init(p->real_parent))
279 continue;
280
281 if (task_pgrp(p->real_parent) != pgrp &&
282 task_session(p->real_parent) == task_session(p))
283 return 0;
284 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
285
286 return 1;
287}
288
289int is_current_pgrp_orphaned(void)
290{
291 int retval;
292
293 read_lock(&tasklist_lock);
294 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
295 read_unlock(&tasklist_lock);
296
297 return retval;
298}
299
300static bool has_stopped_jobs(struct pid *pgrp)
301{
302 struct task_struct *p;
303
304 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
305 if (p->signal->flags & SIGNAL_STOP_STOPPED)
306 return true;
307 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
308
309 return false;
310}
311
312/*
313 * Check to see if any process groups have become orphaned as
314 * a result of our exiting, and if they have any stopped jobs,
315 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
316 */
317static void
318kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
319{
320 struct pid *pgrp = task_pgrp(tsk);
321 struct task_struct *ignored_task = tsk;
322
323 if (!parent)
324 /* exit: our father is in a different pgrp than
325 * we are and we were the only connection outside.
326 */
327 parent = tsk->real_parent;
328 else
329 /* reparent: our child is in a different pgrp than
330 * we are, and it was the only connection outside.
331 */
332 ignored_task = NULL;
333
334 if (task_pgrp(parent) != pgrp &&
335 task_session(parent) == task_session(tsk) &&
336 will_become_orphaned_pgrp(pgrp, ignored_task) &&
337 has_stopped_jobs(pgrp)) {
338 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
339 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
340 }
341}
342
343#ifdef CONFIG_MEMCG
344/*
345 * A task is exiting. If it owned this mm, find a new owner for the mm.
346 */
347void mm_update_next_owner(struct mm_struct *mm)
348{
349 struct task_struct *c, *g, *p = current;
350
351retry:
352 /*
353 * If the exiting or execing task is not the owner, it's
354 * someone else's problem.
355 */
356 if (mm->owner != p)
357 return;
358 /*
359 * The current owner is exiting/execing and there are no other
360 * candidates. Do not leave the mm pointing to a possibly
361 * freed task structure.
362 */
363 if (atomic_read(&mm->mm_users) <= 1) {
364 WRITE_ONCE(mm->owner, NULL);
365 return;
366 }
367
368 read_lock(&tasklist_lock);
369 /*
370 * Search in the children
371 */
372 list_for_each_entry(c, &p->children, sibling) {
373 if (c->mm == mm)
374 goto assign_new_owner;
375 }
376
377 /*
378 * Search in the siblings
379 */
380 list_for_each_entry(c, &p->real_parent->children, sibling) {
381 if (c->mm == mm)
382 goto assign_new_owner;
383 }
384
385 /*
386 * Search through everything else, we should not get here often.
387 */
388 for_each_process(g) {
389 if (g->flags & PF_KTHREAD)
390 continue;
391 for_each_thread(g, c) {
392 if (c->mm == mm)
393 goto assign_new_owner;
394 if (c->mm)
395 break;
396 }
397 }
398 read_unlock(&tasklist_lock);
399 /*
400 * We found no owner yet mm_users > 1: this implies that we are
401 * most likely racing with swapoff (try_to_unuse()) or /proc or
402 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
403 */
404 WRITE_ONCE(mm->owner, NULL);
405 return;
406
407assign_new_owner:
408 BUG_ON(c == p);
409 get_task_struct(c);
410 /*
411 * The task_lock protects c->mm from changing.
412 * We always want mm->owner->mm == mm
413 */
414 task_lock(c);
415 /*
416 * Delay read_unlock() till we have the task_lock()
417 * to ensure that c does not slip away underneath us
418 */
419 read_unlock(&tasklist_lock);
420 if (c->mm != mm) {
421 task_unlock(c);
422 put_task_struct(c);
423 goto retry;
424 }
425 WRITE_ONCE(mm->owner, c);
426 task_unlock(c);
427 put_task_struct(c);
428}
429#endif /* CONFIG_MEMCG */
430
431/*
432 * Turn us into a lazy TLB process if we
433 * aren't already..
434 */
435static void exit_mm(void)
436{
437 struct mm_struct *mm = current->mm;
438 struct core_state *core_state;
439
440 mm_release(current, mm);
441 if (!mm)
442 return;
443 sync_mm_rss(mm);
444 /*
445 * Serialize with any possible pending coredump.
446 * We must hold mmap_sem around checking core_state
447 * and clearing tsk->mm. The core-inducing thread
448 * will increment ->nr_threads for each thread in the
449 * group with ->mm != NULL.
450 */
451 down_read(&mm->mmap_sem);
452 core_state = mm->core_state;
453 if (core_state) {
454 struct core_thread self;
455
456 up_read(&mm->mmap_sem);
457
458 self.task = current;
459 self.next = xchg(&core_state->dumper.next, &self);
460 /*
461 * Implies mb(), the result of xchg() must be visible
462 * to core_state->dumper.
463 */
464 if (atomic_dec_and_test(&core_state->nr_threads))
465 complete(&core_state->startup);
466
467 for (;;) {
468 set_current_state(TASK_UNINTERRUPTIBLE);
469 if (!self.task) /* see coredump_finish() */
470 break;
471 freezable_schedule();
472 }
473 __set_current_state(TASK_RUNNING);
474 down_read(&mm->mmap_sem);
475 }
476 mmgrab(mm);
477 BUG_ON(mm != current->active_mm);
478 /* more a memory barrier than a real lock */
479 task_lock(current);
480 current->mm = NULL;
481 up_read(&mm->mmap_sem);
482 enter_lazy_tlb(mm, current);
483 task_unlock(current);
484 mm_update_next_owner(mm);
485 mmput(mm);
486 if (test_thread_flag(TIF_MEMDIE))
487 exit_oom_victim();
488}
489
490static struct task_struct *find_alive_thread(struct task_struct *p)
491{
492 struct task_struct *t;
493
494 for_each_thread(p, t) {
495 if (!(t->flags & PF_EXITING))
496 return t;
497 }
498 return NULL;
499}
500
501static struct task_struct *find_child_reaper(struct task_struct *father,
502 struct list_head *dead)
503 __releases(&tasklist_lock)
504 __acquires(&tasklist_lock)
505{
506 struct pid_namespace *pid_ns = task_active_pid_ns(father);
507 struct task_struct *reaper = pid_ns->child_reaper;
508 struct task_struct *p, *n;
509
510 if (likely(reaper != father))
511 return reaper;
512
513 reaper = find_alive_thread(father);
514 if (reaper) {
515 pid_ns->child_reaper = reaper;
516 return reaper;
517 }
518
519 write_unlock_irq(&tasklist_lock);
520 if (unlikely(pid_ns == &init_pid_ns)) {
521 panic("Attempted to kill init! exitcode=0x%08x\n",
522 father->signal->group_exit_code ?: father->exit_code);
523 }
524
525 list_for_each_entry_safe(p, n, dead, ptrace_entry) {
526 list_del_init(&p->ptrace_entry);
527 release_task(p);
528 }
529
530 zap_pid_ns_processes(pid_ns);
531 write_lock_irq(&tasklist_lock);
532
533 return father;
534}
535
536/*
537 * When we die, we re-parent all our children, and try to:
538 * 1. give them to another thread in our thread group, if such a member exists
539 * 2. give it to the first ancestor process which prctl'd itself as a
540 * child_subreaper for its children (like a service manager)
541 * 3. give it to the init process (PID 1) in our pid namespace
542 */
543static struct task_struct *find_new_reaper(struct task_struct *father,
544 struct task_struct *child_reaper)
545{
546 struct task_struct *thread, *reaper;
547
548 thread = find_alive_thread(father);
549 if (thread)
550 return thread;
551
552 if (father->signal->has_child_subreaper) {
553 unsigned int ns_level = task_pid(father)->level;
554 /*
555 * Find the first ->is_child_subreaper ancestor in our pid_ns.
556 * We can't check reaper != child_reaper to ensure we do not
557 * cross the namespaces, the exiting parent could be injected
558 * by setns() + fork().
559 * We check pid->level, this is slightly more efficient than
560 * task_active_pid_ns(reaper) != task_active_pid_ns(father).
561 */
562 for (reaper = father->real_parent;
563 task_pid(reaper)->level == ns_level;
564 reaper = reaper->real_parent) {
565 if (reaper == &init_task)
566 break;
567 if (!reaper->signal->is_child_subreaper)
568 continue;
569 thread = find_alive_thread(reaper);
570 if (thread)
571 return thread;
572 }
573 }
574
575 return child_reaper;
576}
577
578/*
579* Any that need to be release_task'd are put on the @dead list.
580 */
581static void reparent_leader(struct task_struct *father, struct task_struct *p,
582 struct list_head *dead)
583{
584 if (unlikely(p->exit_state == EXIT_DEAD))
585 return;
586
587 /* We don't want people slaying init. */
588 p->exit_signal = SIGCHLD;
589
590 /* If it has exited notify the new parent about this child's death. */
591 if (!p->ptrace &&
592 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
593 if (do_notify_parent(p, p->exit_signal)) {
594 p->exit_state = EXIT_DEAD;
595 list_add(&p->ptrace_entry, dead);
596 }
597 }
598
599 kill_orphaned_pgrp(p, father);
600}
601
602/*
603 * This does two things:
604 *
605 * A. Make init inherit all the child processes
606 * B. Check to see if any process groups have become orphaned
607 * as a result of our exiting, and if they have any stopped
608 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
609 */
610static void forget_original_parent(struct task_struct *father,
611 struct list_head *dead)
612{
613 struct task_struct *p, *t, *reaper;
614
615 if (unlikely(!list_empty(&father->ptraced)))
616 exit_ptrace(father, dead);
617
618 /* Can drop and reacquire tasklist_lock */
619 reaper = find_child_reaper(father, dead);
620 if (list_empty(&father->children))
621 return;
622
623 reaper = find_new_reaper(father, reaper);
624 list_for_each_entry(p, &father->children, sibling) {
625 for_each_thread(p, t) {
626 t->real_parent = reaper;
627 BUG_ON((!t->ptrace) != (t->parent == father));
628 if (likely(!t->ptrace))
629 t->parent = t->real_parent;
630 if (t->pdeath_signal)
631 group_send_sig_info(t->pdeath_signal,
632 SEND_SIG_NOINFO, t,
633 PIDTYPE_TGID);
634 }
635 /*
636 * If this is a threaded reparent there is no need to
637 * notify anyone anything has happened.
638 */
639 if (!same_thread_group(reaper, father))
640 reparent_leader(father, p, dead);
641 }
642 list_splice_tail_init(&father->children, &reaper->children);
643}
644
645/*
646 * Send signals to all our closest relatives so that they know
647 * to properly mourn us..
648 */
649static void exit_notify(struct task_struct *tsk, int group_dead)
650{
651 bool autoreap;
652 struct task_struct *p, *n;
653 LIST_HEAD(dead);
654
655 write_lock_irq(&tasklist_lock);
656 forget_original_parent(tsk, &dead);
657
658 if (group_dead)
659 kill_orphaned_pgrp(tsk->group_leader, NULL);
660
661 tsk->exit_state = EXIT_ZOMBIE;
662 if (unlikely(tsk->ptrace)) {
663 int sig = thread_group_leader(tsk) &&
664 thread_group_empty(tsk) &&
665 !ptrace_reparented(tsk) ?
666 tsk->exit_signal : SIGCHLD;
667 autoreap = do_notify_parent(tsk, sig);
668 } else if (thread_group_leader(tsk)) {
669 autoreap = thread_group_empty(tsk) &&
670 do_notify_parent(tsk, tsk->exit_signal);
671 } else {
672 autoreap = true;
673 }
674
675 if (autoreap) {
676 tsk->exit_state = EXIT_DEAD;
677 list_add(&tsk->ptrace_entry, &dead);
678 }
679
680 /* mt-exec, de_thread() is waiting for group leader */
681 if (unlikely(tsk->signal->notify_count < 0))
682 wake_up_process(tsk->signal->group_exit_task);
683 write_unlock_irq(&tasklist_lock);
684
685 list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
686 list_del_init(&p->ptrace_entry);
687 release_task(p);
688 }
689}
690
691#ifdef CONFIG_DEBUG_STACK_USAGE
692static void check_stack_usage(void)
693{
694 static DEFINE_SPINLOCK(low_water_lock);
695 static int lowest_to_date = THREAD_SIZE;
696 unsigned long free;
697
698 free = stack_not_used(current);
699
700 if (free >= lowest_to_date)
701 return;
702
703 spin_lock(&low_water_lock);
704 if (free < lowest_to_date) {
705 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
706 current->comm, task_pid_nr(current), free);
707 lowest_to_date = free;
708 }
709 spin_unlock(&low_water_lock);
710}
711#else
712static inline void check_stack_usage(void) {}
713#endif
714
715void __noreturn do_exit(long code)
716{
717 struct task_struct *tsk = current;
718 int group_dead;
719
720 profile_task_exit(tsk);
721 kcov_task_exit(tsk);
722
723 WARN_ON(blk_needs_flush_plug(tsk));
724
725 if (unlikely(in_interrupt()))
726 panic("Aiee, killing interrupt handler!");
727 if (unlikely(!tsk->pid))
728 panic("Attempted to kill the idle task!");
729
730 /*
731 * If do_exit is called because this processes oopsed, it's possible
732 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
733 * continuing. Amongst other possible reasons, this is to prevent
734 * mm_release()->clear_child_tid() from writing to a user-controlled
735 * kernel address.
736 */
737 set_fs(USER_DS);
738
739 ptrace_event(PTRACE_EVENT_EXIT, code);
740
741 validate_creds_for_do_exit(tsk);
742
743 /*
744 * We're taking recursive faults here in do_exit. Safest is to just
745 * leave this task alone and wait for reboot.
746 */
747 if (unlikely(tsk->flags & PF_EXITING)) {
748 pr_alert("Fixing recursive fault but reboot is needed!\n");
749 /*
750 * We can do this unlocked here. The futex code uses
751 * this flag just to verify whether the pi state
752 * cleanup has been done or not. In the worst case it
753 * loops once more. We pretend that the cleanup was
754 * done as there is no way to return. Either the
755 * OWNER_DIED bit is set by now or we push the blocked
756 * task into the wait for ever nirwana as well.
757 */
758 tsk->flags |= PF_EXITPIDONE;
759 set_current_state(TASK_UNINTERRUPTIBLE);
760 schedule();
761 }
762
763 exit_signals(tsk); /* sets PF_EXITING */
764 /*
765 * Ensure that all new tsk->pi_lock acquisitions must observe
766 * PF_EXITING. Serializes against futex.c:attach_to_pi_owner().
767 */
768 smp_mb();
769 /*
770 * Ensure that we must observe the pi_state in exit_mm() ->
771 * mm_release() -> exit_pi_state_list().
772 */
773 raw_spin_lock_irq(&tsk->pi_lock);
774 raw_spin_unlock_irq(&tsk->pi_lock);
775
776 if (unlikely(in_atomic())) {
777 pr_info("note: %s[%d] exited with preempt_count %d\n",
778 current->comm, task_pid_nr(current),
779 preempt_count());
780 preempt_count_set(PREEMPT_ENABLED);
781 }
782
783 /* sync mm's RSS info before statistics gathering */
784 if (tsk->mm)
785 sync_mm_rss(tsk->mm);
786 acct_update_integrals(tsk);
787 group_dead = atomic_dec_and_test(&tsk->signal->live);
788 if (group_dead) {
789#ifdef CONFIG_POSIX_TIMERS
790 hrtimer_cancel(&tsk->signal->real_timer);
791 exit_itimers(tsk->signal);
792#endif
793 if (tsk->mm)
794 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
795 }
796 acct_collect(code, group_dead);
797 if (group_dead)
798 tty_audit_exit();
799 audit_free(tsk);
800
801 tsk->exit_code = code;
802 taskstats_exit(tsk, group_dead);
803
804 exit_mm();
805
806 if (group_dead)
807 acct_process();
808 trace_sched_process_exit(tsk);
809
810 exit_sem(tsk);
811 exit_shm(tsk);
812 exit_files(tsk);
813 exit_fs(tsk);
814 if (group_dead)
815 disassociate_ctty(1);
816 exit_task_namespaces(tsk);
817 exit_task_work(tsk);
818 exit_thread(tsk);
819 exit_umh(tsk);
820
821 /*
822 * Flush inherited counters to the parent - before the parent
823 * gets woken up by child-exit notifications.
824 *
825 * because of cgroup mode, must be called before cgroup_exit()
826 */
827 perf_event_exit_task(tsk);
828
829 sched_autogroup_exit_task(tsk);
830 cgroup_exit(tsk);
831
832 /*
833 * FIXME: do that only when needed, using sched_exit tracepoint
834 */
835 flush_ptrace_hw_breakpoint(tsk);
836
837 exit_tasks_rcu_start();
838 exit_notify(tsk, group_dead);
839 proc_exit_connector(tsk);
840 mpol_put_task_policy(tsk);
841#ifdef CONFIG_FUTEX
842 if (unlikely(current->pi_state_cache))
843 kfree(current->pi_state_cache);
844#endif
845 /*
846 * Make sure we are holding no locks:
847 */
848 debug_check_no_locks_held();
849 /*
850 * We can do this unlocked here. The futex code uses this flag
851 * just to verify whether the pi state cleanup has been done
852 * or not. In the worst case it loops once more.
853 */
854 tsk->flags |= PF_EXITPIDONE;
855
856 if (tsk->io_context)
857 exit_io_context(tsk);
858
859 if (tsk->splice_pipe)
860 free_pipe_info(tsk->splice_pipe);
861
862 if (tsk->task_frag.page)
863 put_page(tsk->task_frag.page);
864
865 validate_creds_for_do_exit(tsk);
866
867 check_stack_usage();
868 preempt_disable();
869 if (tsk->nr_dirtied)
870 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
871 exit_rcu();
872 exit_tasks_rcu_finish();
873
874 lockdep_free_task(tsk);
875 do_task_dead();
876}
877EXPORT_SYMBOL_GPL(do_exit);
878
879void complete_and_exit(struct completion *comp, long code)
880{
881 if (comp)
882 complete(comp);
883
884 do_exit(code);
885}
886EXPORT_SYMBOL(complete_and_exit);
887
888SYSCALL_DEFINE1(exit, int, error_code)
889{
890 do_exit((error_code&0xff)<<8);
891}
892
893/*
894 * Take down every thread in the group. This is called by fatal signals
895 * as well as by sys_exit_group (below).
896 */
897void
898do_group_exit(int exit_code)
899{
900 struct signal_struct *sig = current->signal;
901
902 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
903
904 if (signal_group_exit(sig))
905 exit_code = sig->group_exit_code;
906 else if (!thread_group_empty(current)) {
907 struct sighand_struct *const sighand = current->sighand;
908
909 spin_lock_irq(&sighand->siglock);
910 if (signal_group_exit(sig))
911 /* Another thread got here before we took the lock. */
912 exit_code = sig->group_exit_code;
913 else {
914 sig->group_exit_code = exit_code;
915 sig->flags = SIGNAL_GROUP_EXIT;
916 zap_other_threads(current);
917 }
918 spin_unlock_irq(&sighand->siglock);
919 }
920
921 do_exit(exit_code);
922 /* NOTREACHED */
923}
924
925/*
926 * this kills every thread in the thread group. Note that any externally
927 * wait4()-ing process will get the correct exit code - even if this
928 * thread is not the thread group leader.
929 */
930SYSCALL_DEFINE1(exit_group, int, error_code)
931{
932 do_group_exit((error_code & 0xff) << 8);
933 /* NOTREACHED */
934 return 0;
935}
936
937struct waitid_info {
938 pid_t pid;
939 uid_t uid;
940 int status;
941 int cause;
942};
943
944struct wait_opts {
945 enum pid_type wo_type;
946 int wo_flags;
947 struct pid *wo_pid;
948
949 struct waitid_info *wo_info;
950 int wo_stat;
951 struct rusage *wo_rusage;
952
953 wait_queue_entry_t child_wait;
954 int notask_error;
955};
956
957static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
958{
959 return wo->wo_type == PIDTYPE_MAX ||
960 task_pid_type(p, wo->wo_type) == wo->wo_pid;
961}
962
963static int
964eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
965{
966 if (!eligible_pid(wo, p))
967 return 0;
968
969 /*
970 * Wait for all children (clone and not) if __WALL is set or
971 * if it is traced by us.
972 */
973 if (ptrace || (wo->wo_flags & __WALL))
974 return 1;
975
976 /*
977 * Otherwise, wait for clone children *only* if __WCLONE is set;
978 * otherwise, wait for non-clone children *only*.
979 *
980 * Note: a "clone" child here is one that reports to its parent
981 * using a signal other than SIGCHLD, or a non-leader thread which
982 * we can only see if it is traced by us.
983 */
984 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
985 return 0;
986
987 return 1;
988}
989
990/*
991 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
992 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
993 * the lock and this task is uninteresting. If we return nonzero, we have
994 * released the lock and the system call should return.
995 */
996static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
997{
998 int state, status;
999 pid_t pid = task_pid_vnr(p);
1000 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1001 struct waitid_info *infop;
1002
1003 if (!likely(wo->wo_flags & WEXITED))
1004 return 0;
1005
1006 if (unlikely(wo->wo_flags & WNOWAIT)) {
1007 status = p->exit_code;
1008 get_task_struct(p);
1009 read_unlock(&tasklist_lock);
1010 sched_annotate_sleep();
1011 if (wo->wo_rusage)
1012 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1013 put_task_struct(p);
1014 goto out_info;
1015 }
1016 /*
1017 * Move the task's state to DEAD/TRACE, only one thread can do this.
1018 */
1019 state = (ptrace_reparented(p) && thread_group_leader(p)) ?
1020 EXIT_TRACE : EXIT_DEAD;
1021 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1022 return 0;
1023 /*
1024 * We own this thread, nobody else can reap it.
1025 */
1026 read_unlock(&tasklist_lock);
1027 sched_annotate_sleep();
1028
1029 /*
1030 * Check thread_group_leader() to exclude the traced sub-threads.
1031 */
1032 if (state == EXIT_DEAD && thread_group_leader(p)) {
1033 struct signal_struct *sig = p->signal;
1034 struct signal_struct *psig = current->signal;
1035 unsigned long maxrss;
1036 u64 tgutime, tgstime;
1037
1038 /*
1039 * The resource counters for the group leader are in its
1040 * own task_struct. Those for dead threads in the group
1041 * are in its signal_struct, as are those for the child
1042 * processes it has previously reaped. All these
1043 * accumulate in the parent's signal_struct c* fields.
1044 *
1045 * We don't bother to take a lock here to protect these
1046 * p->signal fields because the whole thread group is dead
1047 * and nobody can change them.
1048 *
1049 * psig->stats_lock also protects us from our sub-theads
1050 * which can reap other children at the same time. Until
1051 * we change k_getrusage()-like users to rely on this lock
1052 * we have to take ->siglock as well.
1053 *
1054 * We use thread_group_cputime_adjusted() to get times for
1055 * the thread group, which consolidates times for all threads
1056 * in the group including the group leader.
1057 */
1058 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1059 spin_lock_irq(¤t->sighand->siglock);
1060 write_seqlock(&psig->stats_lock);
1061 psig->cutime += tgutime + sig->cutime;
1062 psig->cstime += tgstime + sig->cstime;
1063 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1064 psig->cmin_flt +=
1065 p->min_flt + sig->min_flt + sig->cmin_flt;
1066 psig->cmaj_flt +=
1067 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1068 psig->cnvcsw +=
1069 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1070 psig->cnivcsw +=
1071 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1072 psig->cinblock +=
1073 task_io_get_inblock(p) +
1074 sig->inblock + sig->cinblock;
1075 psig->coublock +=
1076 task_io_get_oublock(p) +
1077 sig->oublock + sig->coublock;
1078 maxrss = max(sig->maxrss, sig->cmaxrss);
1079 if (psig->cmaxrss < maxrss)
1080 psig->cmaxrss = maxrss;
1081 task_io_accounting_add(&psig->ioac, &p->ioac);
1082 task_io_accounting_add(&psig->ioac, &sig->ioac);
1083 write_sequnlock(&psig->stats_lock);
1084 spin_unlock_irq(¤t->sighand->siglock);
1085 }
1086
1087 if (wo->wo_rusage)
1088 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1089 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1090 ? p->signal->group_exit_code : p->exit_code;
1091 wo->wo_stat = status;
1092
1093 if (state == EXIT_TRACE) {
1094 write_lock_irq(&tasklist_lock);
1095 /* We dropped tasklist, ptracer could die and untrace */
1096 ptrace_unlink(p);
1097
1098 /* If parent wants a zombie, don't release it now */
1099 state = EXIT_ZOMBIE;
1100 if (do_notify_parent(p, p->exit_signal))
1101 state = EXIT_DEAD;
1102 p->exit_state = state;
1103 write_unlock_irq(&tasklist_lock);
1104 }
1105 if (state == EXIT_DEAD)
1106 release_task(p);
1107
1108out_info:
1109 infop = wo->wo_info;
1110 if (infop) {
1111 if ((status & 0x7f) == 0) {
1112 infop->cause = CLD_EXITED;
1113 infop->status = status >> 8;
1114 } else {
1115 infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1116 infop->status = status & 0x7f;
1117 }
1118 infop->pid = pid;
1119 infop->uid = uid;
1120 }
1121
1122 return pid;
1123}
1124
1125static int *task_stopped_code(struct task_struct *p, bool ptrace)
1126{
1127 if (ptrace) {
1128 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING))
1129 return &p->exit_code;
1130 } else {
1131 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1132 return &p->signal->group_exit_code;
1133 }
1134 return NULL;
1135}
1136
1137/**
1138 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1139 * @wo: wait options
1140 * @ptrace: is the wait for ptrace
1141 * @p: task to wait for
1142 *
1143 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1144 *
1145 * CONTEXT:
1146 * read_lock(&tasklist_lock), which is released if return value is
1147 * non-zero. Also, grabs and releases @p->sighand->siglock.
1148 *
1149 * RETURNS:
1150 * 0 if wait condition didn't exist and search for other wait conditions
1151 * should continue. Non-zero return, -errno on failure and @p's pid on
1152 * success, implies that tasklist_lock is released and wait condition
1153 * search should terminate.
1154 */
1155static int wait_task_stopped(struct wait_opts *wo,
1156 int ptrace, struct task_struct *p)
1157{
1158 struct waitid_info *infop;
1159 int exit_code, *p_code, why;
1160 uid_t uid = 0; /* unneeded, required by compiler */
1161 pid_t pid;
1162
1163 /*
1164 * Traditionally we see ptrace'd stopped tasks regardless of options.
1165 */
1166 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1167 return 0;
1168
1169 if (!task_stopped_code(p, ptrace))
1170 return 0;
1171
1172 exit_code = 0;
1173 spin_lock_irq(&p->sighand->siglock);
1174
1175 p_code = task_stopped_code(p, ptrace);
1176 if (unlikely(!p_code))
1177 goto unlock_sig;
1178
1179 exit_code = *p_code;
1180 if (!exit_code)
1181 goto unlock_sig;
1182
1183 if (!unlikely(wo->wo_flags & WNOWAIT))
1184 *p_code = 0;
1185
1186 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1187unlock_sig:
1188 spin_unlock_irq(&p->sighand->siglock);
1189 if (!exit_code)
1190 return 0;
1191
1192 /*
1193 * Now we are pretty sure this task is interesting.
1194 * Make sure it doesn't get reaped out from under us while we
1195 * give up the lock and then examine it below. We don't want to
1196 * keep holding onto the tasklist_lock while we call getrusage and
1197 * possibly take page faults for user memory.
1198 */
1199 get_task_struct(p);
1200 pid = task_pid_vnr(p);
1201 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1202 read_unlock(&tasklist_lock);
1203 sched_annotate_sleep();
1204 if (wo->wo_rusage)
1205 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1206 put_task_struct(p);
1207
1208 if (likely(!(wo->wo_flags & WNOWAIT)))
1209 wo->wo_stat = (exit_code << 8) | 0x7f;
1210
1211 infop = wo->wo_info;
1212 if (infop) {
1213 infop->cause = why;
1214 infop->status = exit_code;
1215 infop->pid = pid;
1216 infop->uid = uid;
1217 }
1218 return pid;
1219}
1220
1221/*
1222 * Handle do_wait work for one task in a live, non-stopped state.
1223 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1224 * the lock and this task is uninteresting. If we return nonzero, we have
1225 * released the lock and the system call should return.
1226 */
1227static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1228{
1229 struct waitid_info *infop;
1230 pid_t pid;
1231 uid_t uid;
1232
1233 if (!unlikely(wo->wo_flags & WCONTINUED))
1234 return 0;
1235
1236 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1237 return 0;
1238
1239 spin_lock_irq(&p->sighand->siglock);
1240 /* Re-check with the lock held. */
1241 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1242 spin_unlock_irq(&p->sighand->siglock);
1243 return 0;
1244 }
1245 if (!unlikely(wo->wo_flags & WNOWAIT))
1246 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1247 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1248 spin_unlock_irq(&p->sighand->siglock);
1249
1250 pid = task_pid_vnr(p);
1251 get_task_struct(p);
1252 read_unlock(&tasklist_lock);
1253 sched_annotate_sleep();
1254 if (wo->wo_rusage)
1255 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1256 put_task_struct(p);
1257
1258 infop = wo->wo_info;
1259 if (!infop) {
1260 wo->wo_stat = 0xffff;
1261 } else {
1262 infop->cause = CLD_CONTINUED;
1263 infop->pid = pid;
1264 infop->uid = uid;
1265 infop->status = SIGCONT;
1266 }
1267 return pid;
1268}
1269
1270/*
1271 * Consider @p for a wait by @parent.
1272 *
1273 * -ECHILD should be in ->notask_error before the first call.
1274 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1275 * Returns zero if the search for a child should continue;
1276 * then ->notask_error is 0 if @p is an eligible child,
1277 * or still -ECHILD.
1278 */
1279static int wait_consider_task(struct wait_opts *wo, int ptrace,
1280 struct task_struct *p)
1281{
1282 /*
1283 * We can race with wait_task_zombie() from another thread.
1284 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1285 * can't confuse the checks below.
1286 */
1287 int exit_state = READ_ONCE(p->exit_state);
1288 int ret;
1289
1290 if (unlikely(exit_state == EXIT_DEAD))
1291 return 0;
1292
1293 ret = eligible_child(wo, ptrace, p);
1294 if (!ret)
1295 return ret;
1296
1297 if (unlikely(exit_state == EXIT_TRACE)) {
1298 /*
1299 * ptrace == 0 means we are the natural parent. In this case
1300 * we should clear notask_error, debugger will notify us.
1301 */
1302 if (likely(!ptrace))
1303 wo->notask_error = 0;
1304 return 0;
1305 }
1306
1307 if (likely(!ptrace) && unlikely(p->ptrace)) {
1308 /*
1309 * If it is traced by its real parent's group, just pretend
1310 * the caller is ptrace_do_wait() and reap this child if it
1311 * is zombie.
1312 *
1313 * This also hides group stop state from real parent; otherwise
1314 * a single stop can be reported twice as group and ptrace stop.
1315 * If a ptracer wants to distinguish these two events for its
1316 * own children it should create a separate process which takes
1317 * the role of real parent.
1318 */
1319 if (!ptrace_reparented(p))
1320 ptrace = 1;
1321 }
1322
1323 /* slay zombie? */
1324 if (exit_state == EXIT_ZOMBIE) {
1325 /* we don't reap group leaders with subthreads */
1326 if (!delay_group_leader(p)) {
1327 /*
1328 * A zombie ptracee is only visible to its ptracer.
1329 * Notification and reaping will be cascaded to the
1330 * real parent when the ptracer detaches.
1331 */
1332 if (unlikely(ptrace) || likely(!p->ptrace))
1333 return wait_task_zombie(wo, p);
1334 }
1335
1336 /*
1337 * Allow access to stopped/continued state via zombie by
1338 * falling through. Clearing of notask_error is complex.
1339 *
1340 * When !@ptrace:
1341 *
1342 * If WEXITED is set, notask_error should naturally be
1343 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1344 * so, if there are live subthreads, there are events to
1345 * wait for. If all subthreads are dead, it's still safe
1346 * to clear - this function will be called again in finite
1347 * amount time once all the subthreads are released and
1348 * will then return without clearing.
1349 *
1350 * When @ptrace:
1351 *
1352 * Stopped state is per-task and thus can't change once the
1353 * target task dies. Only continued and exited can happen.
1354 * Clear notask_error if WCONTINUED | WEXITED.
1355 */
1356 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1357 wo->notask_error = 0;
1358 } else {
1359 /*
1360 * @p is alive and it's gonna stop, continue or exit, so
1361 * there always is something to wait for.
1362 */
1363 wo->notask_error = 0;
1364 }
1365
1366 /*
1367 * Wait for stopped. Depending on @ptrace, different stopped state
1368 * is used and the two don't interact with each other.
1369 */
1370 ret = wait_task_stopped(wo, ptrace, p);
1371 if (ret)
1372 return ret;
1373
1374 /*
1375 * Wait for continued. There's only one continued state and the
1376 * ptracer can consume it which can confuse the real parent. Don't
1377 * use WCONTINUED from ptracer. You don't need or want it.
1378 */
1379 return wait_task_continued(wo, p);
1380}
1381
1382/*
1383 * Do the work of do_wait() for one thread in the group, @tsk.
1384 *
1385 * -ECHILD should be in ->notask_error before the first call.
1386 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1387 * Returns zero if the search for a child should continue; then
1388 * ->notask_error is 0 if there were any eligible children,
1389 * or still -ECHILD.
1390 */
1391static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1392{
1393 struct task_struct *p;
1394
1395 list_for_each_entry(p, &tsk->children, sibling) {
1396 int ret = wait_consider_task(wo, 0, p);
1397
1398 if (ret)
1399 return ret;
1400 }
1401
1402 return 0;
1403}
1404
1405static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1406{
1407 struct task_struct *p;
1408
1409 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1410 int ret = wait_consider_task(wo, 1, p);
1411
1412 if (ret)
1413 return ret;
1414 }
1415
1416 return 0;
1417}
1418
1419static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode,
1420 int sync, void *key)
1421{
1422 struct wait_opts *wo = container_of(wait, struct wait_opts,
1423 child_wait);
1424 struct task_struct *p = key;
1425
1426 if (!eligible_pid(wo, p))
1427 return 0;
1428
1429 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1430 return 0;
1431
1432 return default_wake_function(wait, mode, sync, key);
1433}
1434
1435void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1436{
1437 __wake_up_sync_key(&parent->signal->wait_chldexit,
1438 TASK_INTERRUPTIBLE, 1, p);
1439}
1440
1441static long do_wait(struct wait_opts *wo)
1442{
1443 struct task_struct *tsk;
1444 int retval;
1445
1446 trace_sched_process_wait(wo->wo_pid);
1447
1448 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1449 wo->child_wait.private = current;
1450 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1451repeat:
1452 /*
1453 * If there is nothing that can match our criteria, just get out.
1454 * We will clear ->notask_error to zero if we see any child that
1455 * might later match our criteria, even if we are not able to reap
1456 * it yet.
1457 */
1458 wo->notask_error = -ECHILD;
1459 if ((wo->wo_type < PIDTYPE_MAX) &&
1460 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1461 goto notask;
1462
1463 set_current_state(TASK_INTERRUPTIBLE);
1464 read_lock(&tasklist_lock);
1465 tsk = current;
1466 do {
1467 retval = do_wait_thread(wo, tsk);
1468 if (retval)
1469 goto end;
1470
1471 retval = ptrace_do_wait(wo, tsk);
1472 if (retval)
1473 goto end;
1474
1475 if (wo->wo_flags & __WNOTHREAD)
1476 break;
1477 } while_each_thread(current, tsk);
1478 read_unlock(&tasklist_lock);
1479
1480notask:
1481 retval = wo->notask_error;
1482 if (!retval && !(wo->wo_flags & WNOHANG)) {
1483 retval = -ERESTARTSYS;
1484 if (!signal_pending(current)) {
1485 schedule();
1486 goto repeat;
1487 }
1488 }
1489end:
1490 __set_current_state(TASK_RUNNING);
1491 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1492 return retval;
1493}
1494
1495static struct pid *pidfd_get_pid(unsigned int fd)
1496{
1497 struct fd f;
1498 struct pid *pid;
1499
1500 f = fdget(fd);
1501 if (!f.file)
1502 return ERR_PTR(-EBADF);
1503
1504 pid = pidfd_pid(f.file);
1505 if (!IS_ERR(pid))
1506 get_pid(pid);
1507
1508 fdput(f);
1509 return pid;
1510}
1511
1512static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
1513 int options, struct rusage *ru)
1514{
1515 struct wait_opts wo;
1516 struct pid *pid = NULL;
1517 enum pid_type type;
1518 long ret;
1519
1520 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
1521 __WNOTHREAD|__WCLONE|__WALL))
1522 return -EINVAL;
1523 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1524 return -EINVAL;
1525
1526 switch (which) {
1527 case P_ALL:
1528 type = PIDTYPE_MAX;
1529 break;
1530 case P_PID:
1531 type = PIDTYPE_PID;
1532 if (upid <= 0)
1533 return -EINVAL;
1534
1535 pid = find_get_pid(upid);
1536 break;
1537 case P_PGID:
1538 type = PIDTYPE_PGID;
1539 if (upid < 0)
1540 return -EINVAL;
1541
1542 if (upid)
1543 pid = find_get_pid(upid);
1544 else
1545 pid = get_task_pid(current, PIDTYPE_PGID);
1546 break;
1547 case P_PIDFD:
1548 type = PIDTYPE_PID;
1549 if (upid < 0)
1550 return -EINVAL;
1551
1552 pid = pidfd_get_pid(upid);
1553 if (IS_ERR(pid))
1554 return PTR_ERR(pid);
1555 break;
1556 default:
1557 return -EINVAL;
1558 }
1559
1560 wo.wo_type = type;
1561 wo.wo_pid = pid;
1562 wo.wo_flags = options;
1563 wo.wo_info = infop;
1564 wo.wo_rusage = ru;
1565 ret = do_wait(&wo);
1566
1567 put_pid(pid);
1568 return ret;
1569}
1570
1571SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1572 infop, int, options, struct rusage __user *, ru)
1573{
1574 struct rusage r;
1575 struct waitid_info info = {.status = 0};
1576 long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
1577 int signo = 0;
1578
1579 if (err > 0) {
1580 signo = SIGCHLD;
1581 err = 0;
1582 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1583 return -EFAULT;
1584 }
1585 if (!infop)
1586 return err;
1587
1588 if (!user_access_begin(infop, sizeof(*infop)))
1589 return -EFAULT;
1590
1591 unsafe_put_user(signo, &infop->si_signo, Efault);
1592 unsafe_put_user(0, &infop->si_errno, Efault);
1593 unsafe_put_user(info.cause, &infop->si_code, Efault);
1594 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1595 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1596 unsafe_put_user(info.status, &infop->si_status, Efault);
1597 user_access_end();
1598 return err;
1599Efault:
1600 user_access_end();
1601 return -EFAULT;
1602}
1603
1604long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
1605 struct rusage *ru)
1606{
1607 struct wait_opts wo;
1608 struct pid *pid = NULL;
1609 enum pid_type type;
1610 long ret;
1611
1612 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1613 __WNOTHREAD|__WCLONE|__WALL))
1614 return -EINVAL;
1615
1616 /* -INT_MIN is not defined */
1617 if (upid == INT_MIN)
1618 return -ESRCH;
1619
1620 if (upid == -1)
1621 type = PIDTYPE_MAX;
1622 else if (upid < 0) {
1623 type = PIDTYPE_PGID;
1624 pid = find_get_pid(-upid);
1625 } else if (upid == 0) {
1626 type = PIDTYPE_PGID;
1627 pid = get_task_pid(current, PIDTYPE_PGID);
1628 } else /* upid > 0 */ {
1629 type = PIDTYPE_PID;
1630 pid = find_get_pid(upid);
1631 }
1632
1633 wo.wo_type = type;
1634 wo.wo_pid = pid;
1635 wo.wo_flags = options | WEXITED;
1636 wo.wo_info = NULL;
1637 wo.wo_stat = 0;
1638 wo.wo_rusage = ru;
1639 ret = do_wait(&wo);
1640 put_pid(pid);
1641 if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
1642 ret = -EFAULT;
1643
1644 return ret;
1645}
1646
1647SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1648 int, options, struct rusage __user *, ru)
1649{
1650 struct rusage r;
1651 long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL);
1652
1653 if (err > 0) {
1654 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1655 return -EFAULT;
1656 }
1657 return err;
1658}
1659
1660#ifdef __ARCH_WANT_SYS_WAITPID
1661
1662/*
1663 * sys_waitpid() remains for compatibility. waitpid() should be
1664 * implemented by calling sys_wait4() from libc.a.
1665 */
1666SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1667{
1668 return kernel_wait4(pid, stat_addr, options, NULL);
1669}
1670
1671#endif
1672
1673#ifdef CONFIG_COMPAT
1674COMPAT_SYSCALL_DEFINE4(wait4,
1675 compat_pid_t, pid,
1676 compat_uint_t __user *, stat_addr,
1677 int, options,
1678 struct compat_rusage __user *, ru)
1679{
1680 struct rusage r;
1681 long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL);
1682 if (err > 0) {
1683 if (ru && put_compat_rusage(&r, ru))
1684 return -EFAULT;
1685 }
1686 return err;
1687}
1688
1689COMPAT_SYSCALL_DEFINE5(waitid,
1690 int, which, compat_pid_t, pid,
1691 struct compat_siginfo __user *, infop, int, options,
1692 struct compat_rusage __user *, uru)
1693{
1694 struct rusage ru;
1695 struct waitid_info info = {.status = 0};
1696 long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);
1697 int signo = 0;
1698 if (err > 0) {
1699 signo = SIGCHLD;
1700 err = 0;
1701 if (uru) {
1702 /* kernel_waitid() overwrites everything in ru */
1703 if (COMPAT_USE_64BIT_TIME)
1704 err = copy_to_user(uru, &ru, sizeof(ru));
1705 else
1706 err = put_compat_rusage(&ru, uru);
1707 if (err)
1708 return -EFAULT;
1709 }
1710 }
1711
1712 if (!infop)
1713 return err;
1714
1715 if (!user_access_begin(infop, sizeof(*infop)))
1716 return -EFAULT;
1717
1718 unsafe_put_user(signo, &infop->si_signo, Efault);
1719 unsafe_put_user(0, &infop->si_errno, Efault);
1720 unsafe_put_user(info.cause, &infop->si_code, Efault);
1721 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1722 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1723 unsafe_put_user(info.status, &infop->si_status, Efault);
1724 user_access_end();
1725 return err;
1726Efault:
1727 user_access_end();
1728 return -EFAULT;
1729}
1730#endif
1731
1732__weak void abort(void)
1733{
1734 BUG();
1735
1736 /* if that doesn't kill us, halt */
1737 panic("Oops failed to kill thread");
1738}
1739EXPORT_SYMBOL(abort);
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#include <linux/writeback.h>
55#include <linux/shm.h>
56
57#include <asm/uaccess.h>
58#include <asm/unistd.h>
59#include <asm/pgtable.h>
60#include <asm/mmu_context.h>
61
62static void exit_mm(struct task_struct * tsk);
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 * If we are the last child process in a pid namespace to be
77 * reaped, notify the reaper sleeping zap_pid_ns_processes().
78 */
79 if (IS_ENABLED(CONFIG_PID_NS)) {
80 struct task_struct *parent = p->real_parent;
81
82 if ((task_active_pid_ns(parent)->child_reaper == parent) &&
83 list_empty(&parent->children) &&
84 (parent->flags & PF_EXITING))
85 wake_up_process(parent);
86 }
87 }
88 list_del_rcu(&p->thread_group);
89}
90
91/*
92 * This function expects the tasklist_lock write-locked.
93 */
94static void __exit_signal(struct task_struct *tsk)
95{
96 struct signal_struct *sig = tsk->signal;
97 bool group_dead = thread_group_leader(tsk);
98 struct sighand_struct *sighand;
99 struct tty_struct *uninitialized_var(tty);
100
101 sighand = rcu_dereference_check(tsk->sighand,
102 lockdep_tasklist_lock_is_held());
103 spin_lock(&sighand->siglock);
104
105 posix_cpu_timers_exit(tsk);
106 if (group_dead) {
107 posix_cpu_timers_exit_group(tsk);
108 tty = sig->tty;
109 sig->tty = NULL;
110 } else {
111 /*
112 * This can only happen if the caller is de_thread().
113 * FIXME: this is the temporary hack, we should teach
114 * posix-cpu-timers to handle this case correctly.
115 */
116 if (unlikely(has_group_leader_pid(tsk)))
117 posix_cpu_timers_exit_group(tsk);
118
119 /*
120 * If there is any task waiting for the group exit
121 * then notify it:
122 */
123 if (sig->notify_count > 0 && !--sig->notify_count)
124 wake_up_process(sig->group_exit_task);
125
126 if (tsk == sig->curr_target)
127 sig->curr_target = next_thread(tsk);
128 /*
129 * Accumulate here the counters for all threads but the
130 * group leader as they die, so they can be added into
131 * the process-wide totals when those are taken.
132 * The group leader stays around as a zombie as long
133 * as there are other threads. When it gets reaped,
134 * the exit.c code will add its counts into these totals.
135 * We won't ever get here for the group leader, since it
136 * will have been the last reference on the signal_struct.
137 */
138 sig->utime += tsk->utime;
139 sig->stime += tsk->stime;
140 sig->gtime += tsk->gtime;
141 sig->min_flt += tsk->min_flt;
142 sig->maj_flt += tsk->maj_flt;
143 sig->nvcsw += tsk->nvcsw;
144 sig->nivcsw += tsk->nivcsw;
145 sig->inblock += task_io_get_inblock(tsk);
146 sig->oublock += task_io_get_oublock(tsk);
147 task_io_accounting_add(&sig->ioac, &tsk->ioac);
148 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
149 }
150
151 sig->nr_threads--;
152 __unhash_process(tsk, group_dead);
153
154 /*
155 * Do this under ->siglock, we can race with another thread
156 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
157 */
158 flush_sigqueue(&tsk->pending);
159 tsk->sighand = NULL;
160 spin_unlock(&sighand->siglock);
161
162 __cleanup_sighand(sighand);
163 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
164 if (group_dead) {
165 flush_sigqueue(&sig->shared_pending);
166 tty_kref_put(tty);
167 }
168}
169
170static void delayed_put_task_struct(struct rcu_head *rhp)
171{
172 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
173
174 perf_event_delayed_put(tsk);
175 trace_sched_process_free(tsk);
176 put_task_struct(tsk);
177}
178
179
180void release_task(struct task_struct * p)
181{
182 struct task_struct *leader;
183 int zap_leader;
184repeat:
185 /* don't need to get the RCU readlock here - the process is dead and
186 * can't be modifying its own credentials. But shut RCU-lockdep up */
187 rcu_read_lock();
188 atomic_dec(&__task_cred(p)->user->processes);
189 rcu_read_unlock();
190
191 proc_flush_task(p);
192
193 write_lock_irq(&tasklist_lock);
194 ptrace_release_task(p);
195 __exit_signal(p);
196
197 /*
198 * If we are the last non-leader member of the thread
199 * group, and the leader is zombie, then notify the
200 * group leader's parent process. (if it wants notification.)
201 */
202 zap_leader = 0;
203 leader = p->group_leader;
204 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
205 /*
206 * If we were the last child thread and the leader has
207 * exited already, and the leader's parent ignores SIGCHLD,
208 * then we are the one who should release the leader.
209 */
210 zap_leader = do_notify_parent(leader, leader->exit_signal);
211 if (zap_leader)
212 leader->exit_state = EXIT_DEAD;
213 }
214
215 write_unlock_irq(&tasklist_lock);
216 release_thread(p);
217 call_rcu(&p->rcu, delayed_put_task_struct);
218
219 p = leader;
220 if (unlikely(zap_leader))
221 goto repeat;
222}
223
224/*
225 * This checks not only the pgrp, but falls back on the pid if no
226 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
227 * without this...
228 *
229 * The caller must hold rcu lock or the tasklist lock.
230 */
231struct pid *session_of_pgrp(struct pid *pgrp)
232{
233 struct task_struct *p;
234 struct pid *sid = NULL;
235
236 p = pid_task(pgrp, PIDTYPE_PGID);
237 if (p == NULL)
238 p = pid_task(pgrp, PIDTYPE_PID);
239 if (p != NULL)
240 sid = task_session(p);
241
242 return sid;
243}
244
245/*
246 * Determine if a process group is "orphaned", according to the POSIX
247 * definition in 2.2.2.52. Orphaned process groups are not to be affected
248 * by terminal-generated stop signals. Newly orphaned process groups are
249 * to receive a SIGHUP and a SIGCONT.
250 *
251 * "I ask you, have you ever known what it is to be an orphan?"
252 */
253static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
254{
255 struct task_struct *p;
256
257 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
258 if ((p == ignored_task) ||
259 (p->exit_state && thread_group_empty(p)) ||
260 is_global_init(p->real_parent))
261 continue;
262
263 if (task_pgrp(p->real_parent) != pgrp &&
264 task_session(p->real_parent) == task_session(p))
265 return 0;
266 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
267
268 return 1;
269}
270
271int is_current_pgrp_orphaned(void)
272{
273 int retval;
274
275 read_lock(&tasklist_lock);
276 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
277 read_unlock(&tasklist_lock);
278
279 return retval;
280}
281
282static bool has_stopped_jobs(struct pid *pgrp)
283{
284 struct task_struct *p;
285
286 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
287 if (p->signal->flags & SIGNAL_STOP_STOPPED)
288 return true;
289 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
290
291 return false;
292}
293
294/*
295 * Check to see if any process groups have become orphaned as
296 * a result of our exiting, and if they have any stopped jobs,
297 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
298 */
299static void
300kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
301{
302 struct pid *pgrp = task_pgrp(tsk);
303 struct task_struct *ignored_task = tsk;
304
305 if (!parent)
306 /* exit: our father is in a different pgrp than
307 * we are and we were the only connection outside.
308 */
309 parent = tsk->real_parent;
310 else
311 /* reparent: our child is in a different pgrp than
312 * we are, and it was the only connection outside.
313 */
314 ignored_task = NULL;
315
316 if (task_pgrp(parent) != pgrp &&
317 task_session(parent) == task_session(tsk) &&
318 will_become_orphaned_pgrp(pgrp, ignored_task) &&
319 has_stopped_jobs(pgrp)) {
320 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
321 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
322 }
323}
324
325/**
326 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
327 *
328 * If a kernel thread is launched as a result of a system call, or if
329 * it ever exits, it should generally reparent itself to kthreadd so it
330 * isn't in the way of other processes and is correctly cleaned up on exit.
331 *
332 * The various task state such as scheduling policy and priority may have
333 * been inherited from a user process, so we reset them to sane values here.
334 *
335 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
336 */
337static void reparent_to_kthreadd(void)
338{
339 write_lock_irq(&tasklist_lock);
340
341 ptrace_unlink(current);
342 /* Reparent to init */
343 current->real_parent = current->parent = kthreadd_task;
344 list_move_tail(¤t->sibling, ¤t->real_parent->children);
345
346 /* Set the exit signal to SIGCHLD so we signal init on exit */
347 current->exit_signal = SIGCHLD;
348
349 if (task_nice(current) < 0)
350 set_user_nice(current, 0);
351 /* cpus_allowed? */
352 /* rt_priority? */
353 /* signals? */
354 memcpy(current->signal->rlim, init_task.signal->rlim,
355 sizeof(current->signal->rlim));
356
357 atomic_inc(&init_cred.usage);
358 commit_creds(&init_cred);
359 write_unlock_irq(&tasklist_lock);
360}
361
362void __set_special_pids(struct pid *pid)
363{
364 struct task_struct *curr = current->group_leader;
365
366 if (task_session(curr) != pid)
367 change_pid(curr, PIDTYPE_SID, pid);
368
369 if (task_pgrp(curr) != pid)
370 change_pid(curr, PIDTYPE_PGID, pid);
371}
372
373static void set_special_pids(struct pid *pid)
374{
375 write_lock_irq(&tasklist_lock);
376 __set_special_pids(pid);
377 write_unlock_irq(&tasklist_lock);
378}
379
380/*
381 * Let kernel threads use this to say that they allow a certain signal.
382 * Must not be used if kthread was cloned with CLONE_SIGHAND.
383 */
384int allow_signal(int sig)
385{
386 if (!valid_signal(sig) || sig < 1)
387 return -EINVAL;
388
389 spin_lock_irq(¤t->sighand->siglock);
390 /* This is only needed for daemonize()'ed kthreads */
391 sigdelset(¤t->blocked, sig);
392 /*
393 * Kernel threads handle their own signals. Let the signal code
394 * know it'll be handled, so that they don't get converted to
395 * SIGKILL or just silently dropped.
396 */
397 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
398 recalc_sigpending();
399 spin_unlock_irq(¤t->sighand->siglock);
400 return 0;
401}
402
403EXPORT_SYMBOL(allow_signal);
404
405int disallow_signal(int sig)
406{
407 if (!valid_signal(sig) || sig < 1)
408 return -EINVAL;
409
410 spin_lock_irq(¤t->sighand->siglock);
411 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
412 recalc_sigpending();
413 spin_unlock_irq(¤t->sighand->siglock);
414 return 0;
415}
416
417EXPORT_SYMBOL(disallow_signal);
418
419/*
420 * Put all the gunge required to become a kernel thread without
421 * attached user resources in one place where it belongs.
422 */
423
424void daemonize(const char *name, ...)
425{
426 va_list args;
427 sigset_t blocked;
428
429 va_start(args, name);
430 vsnprintf(current->comm, sizeof(current->comm), name, args);
431 va_end(args);
432
433 /*
434 * If we were started as result of loading a module, close all of the
435 * user space pages. We don't need them, and if we didn't close them
436 * they would be locked into memory.
437 */
438 exit_mm(current);
439 /*
440 * We don't want to get frozen, in case system-wide hibernation
441 * or suspend transition begins right now.
442 */
443 current->flags |= (PF_NOFREEZE | PF_KTHREAD);
444
445 if (current->nsproxy != &init_nsproxy) {
446 get_nsproxy(&init_nsproxy);
447 switch_task_namespaces(current, &init_nsproxy);
448 }
449 set_special_pids(&init_struct_pid);
450 proc_clear_tty(current);
451
452 /* Block and flush all signals */
453 sigfillset(&blocked);
454 sigprocmask(SIG_BLOCK, &blocked, NULL);
455 flush_signals(current);
456
457 /* Become as one with the init task */
458
459 daemonize_fs_struct();
460 exit_files(current);
461 current->files = init_task.files;
462 atomic_inc(¤t->files->count);
463
464 reparent_to_kthreadd();
465}
466
467EXPORT_SYMBOL(daemonize);
468
469static void close_files(struct files_struct * files)
470{
471 int i, j;
472 struct fdtable *fdt;
473
474 j = 0;
475
476 /*
477 * It is safe to dereference the fd table without RCU or
478 * ->file_lock because this is the last reference to the
479 * files structure. But use RCU to shut RCU-lockdep up.
480 */
481 rcu_read_lock();
482 fdt = files_fdtable(files);
483 rcu_read_unlock();
484 for (;;) {
485 unsigned long set;
486 i = j * BITS_PER_LONG;
487 if (i >= fdt->max_fds)
488 break;
489 set = fdt->open_fds[j++];
490 while (set) {
491 if (set & 1) {
492 struct file * file = xchg(&fdt->fd[i], NULL);
493 if (file) {
494 filp_close(file, files);
495 cond_resched();
496 }
497 }
498 i++;
499 set >>= 1;
500 }
501 }
502}
503
504struct files_struct *get_files_struct(struct task_struct *task)
505{
506 struct files_struct *files;
507
508 task_lock(task);
509 files = task->files;
510 if (files)
511 atomic_inc(&files->count);
512 task_unlock(task);
513
514 return files;
515}
516
517void put_files_struct(struct files_struct *files)
518{
519 struct fdtable *fdt;
520
521 if (atomic_dec_and_test(&files->count)) {
522 close_files(files);
523 /*
524 * Free the fd and fdset arrays if we expanded them.
525 * If the fdtable was embedded, pass files for freeing
526 * at the end of the RCU grace period. Otherwise,
527 * you can free files immediately.
528 */
529 rcu_read_lock();
530 fdt = files_fdtable(files);
531 if (fdt != &files->fdtab)
532 kmem_cache_free(files_cachep, files);
533 free_fdtable(fdt);
534 rcu_read_unlock();
535 }
536}
537
538void reset_files_struct(struct files_struct *files)
539{
540 struct task_struct *tsk = current;
541 struct files_struct *old;
542
543 old = tsk->files;
544 task_lock(tsk);
545 tsk->files = files;
546 task_unlock(tsk);
547 put_files_struct(old);
548}
549
550void exit_files(struct task_struct *tsk)
551{
552 struct files_struct * files = tsk->files;
553
554 if (files) {
555 task_lock(tsk);
556 tsk->files = NULL;
557 task_unlock(tsk);
558 put_files_struct(files);
559 }
560}
561
562#ifdef CONFIG_MM_OWNER
563/*
564 * A task is exiting. If it owned this mm, find a new owner for the mm.
565 */
566void mm_update_next_owner(struct mm_struct *mm)
567{
568 struct task_struct *c, *g, *p = current;
569
570retry:
571 /*
572 * If the exiting or execing task is not the owner, it's
573 * someone else's problem.
574 */
575 if (mm->owner != p)
576 return;
577 /*
578 * The current owner is exiting/execing and there are no other
579 * candidates. Do not leave the mm pointing to a possibly
580 * freed task structure.
581 */
582 if (atomic_read(&mm->mm_users) <= 1) {
583 mm->owner = NULL;
584 return;
585 }
586
587 read_lock(&tasklist_lock);
588 /*
589 * Search in the children
590 */
591 list_for_each_entry(c, &p->children, sibling) {
592 if (c->mm == mm)
593 goto assign_new_owner;
594 }
595
596 /*
597 * Search in the siblings
598 */
599 list_for_each_entry(c, &p->real_parent->children, sibling) {
600 if (c->mm == mm)
601 goto assign_new_owner;
602 }
603
604 /*
605 * Search through everything else. We should not get
606 * here often
607 */
608 do_each_thread(g, c) {
609 if (c->mm == mm)
610 goto assign_new_owner;
611 } while_each_thread(g, c);
612
613 read_unlock(&tasklist_lock);
614 /*
615 * We found no owner yet mm_users > 1: this implies that we are
616 * most likely racing with swapoff (try_to_unuse()) or /proc or
617 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
618 */
619 mm->owner = NULL;
620 return;
621
622assign_new_owner:
623 BUG_ON(c == p);
624 get_task_struct(c);
625 /*
626 * The task_lock protects c->mm from changing.
627 * We always want mm->owner->mm == mm
628 */
629 task_lock(c);
630 /*
631 * Delay read_unlock() till we have the task_lock()
632 * to ensure that c does not slip away underneath us
633 */
634 read_unlock(&tasklist_lock);
635 if (c->mm != mm) {
636 task_unlock(c);
637 put_task_struct(c);
638 goto retry;
639 }
640 mm->owner = c;
641 task_unlock(c);
642 put_task_struct(c);
643}
644#endif /* CONFIG_MM_OWNER */
645
646/*
647 * Turn us into a lazy TLB process if we
648 * aren't already..
649 */
650static void exit_mm(struct task_struct * tsk)
651{
652 struct mm_struct *mm = tsk->mm;
653 struct core_state *core_state;
654
655 mm_release(tsk, mm);
656 if (!mm)
657 return;
658 sync_mm_rss(mm);
659 /*
660 * Serialize with any possible pending coredump.
661 * We must hold mmap_sem around checking core_state
662 * and clearing tsk->mm. The core-inducing thread
663 * will increment ->nr_threads for each thread in the
664 * group with ->mm != NULL.
665 */
666 down_read(&mm->mmap_sem);
667 core_state = mm->core_state;
668 if (core_state) {
669 struct core_thread self;
670 up_read(&mm->mmap_sem);
671
672 self.task = tsk;
673 self.next = xchg(&core_state->dumper.next, &self);
674 /*
675 * Implies mb(), the result of xchg() must be visible
676 * to core_state->dumper.
677 */
678 if (atomic_dec_and_test(&core_state->nr_threads))
679 complete(&core_state->startup);
680
681 for (;;) {
682 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
683 if (!self.task) /* see coredump_finish() */
684 break;
685 schedule();
686 }
687 __set_task_state(tsk, TASK_RUNNING);
688 down_read(&mm->mmap_sem);
689 }
690 atomic_inc(&mm->mm_count);
691 BUG_ON(mm != tsk->active_mm);
692 /* more a memory barrier than a real lock */
693 task_lock(tsk);
694 tsk->mm = NULL;
695 up_read(&mm->mmap_sem);
696 enter_lazy_tlb(mm, current);
697 task_unlock(tsk);
698 mm_update_next_owner(mm);
699 mmput(mm);
700}
701
702/*
703 * When we die, we re-parent all our children, and try to:
704 * 1. give them to another thread in our thread group, if such a member exists
705 * 2. give it to the first ancestor process which prctl'd itself as a
706 * child_subreaper for its children (like a service manager)
707 * 3. give it to the init process (PID 1) in our pid namespace
708 */
709static struct task_struct *find_new_reaper(struct task_struct *father)
710 __releases(&tasklist_lock)
711 __acquires(&tasklist_lock)
712{
713 struct pid_namespace *pid_ns = task_active_pid_ns(father);
714 struct task_struct *thread;
715
716 thread = father;
717 while_each_thread(father, thread) {
718 if (thread->flags & PF_EXITING)
719 continue;
720 if (unlikely(pid_ns->child_reaper == father))
721 pid_ns->child_reaper = thread;
722 return thread;
723 }
724
725 if (unlikely(pid_ns->child_reaper == father)) {
726 write_unlock_irq(&tasklist_lock);
727 if (unlikely(pid_ns == &init_pid_ns)) {
728 panic("Attempted to kill init! exitcode=0x%08x\n",
729 father->signal->group_exit_code ?:
730 father->exit_code);
731 }
732
733 zap_pid_ns_processes(pid_ns);
734 write_lock_irq(&tasklist_lock);
735 } else if (father->signal->has_child_subreaper) {
736 struct task_struct *reaper;
737
738 /*
739 * Find the first ancestor marked as child_subreaper.
740 * Note that the code below checks same_thread_group(reaper,
741 * pid_ns->child_reaper). This is what we need to DTRT in a
742 * PID namespace. However we still need the check above, see
743 * http://marc.info/?l=linux-kernel&m=131385460420380
744 */
745 for (reaper = father->real_parent;
746 reaper != &init_task;
747 reaper = reaper->real_parent) {
748 if (same_thread_group(reaper, pid_ns->child_reaper))
749 break;
750 if (!reaper->signal->is_child_subreaper)
751 continue;
752 thread = reaper;
753 do {
754 if (!(thread->flags & PF_EXITING))
755 return reaper;
756 } while_each_thread(reaper, thread);
757 }
758 }
759
760 return pid_ns->child_reaper;
761}
762
763/*
764* Any that need to be release_task'd are put on the @dead list.
765 */
766static void reparent_leader(struct task_struct *father, struct task_struct *p,
767 struct list_head *dead)
768{
769 list_move_tail(&p->sibling, &p->real_parent->children);
770
771 if (p->exit_state == EXIT_DEAD)
772 return;
773 /*
774 * If this is a threaded reparent there is no need to
775 * notify anyone anything has happened.
776 */
777 if (same_thread_group(p->real_parent, father))
778 return;
779
780 /* We don't want people slaying init. */
781 p->exit_signal = SIGCHLD;
782
783 /* If it has exited notify the new parent about this child's death. */
784 if (!p->ptrace &&
785 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
786 if (do_notify_parent(p, p->exit_signal)) {
787 p->exit_state = EXIT_DEAD;
788 list_move_tail(&p->sibling, dead);
789 }
790 }
791
792 kill_orphaned_pgrp(p, father);
793}
794
795static void forget_original_parent(struct task_struct *father)
796{
797 struct task_struct *p, *n, *reaper;
798 LIST_HEAD(dead_children);
799
800 write_lock_irq(&tasklist_lock);
801 /*
802 * Note that exit_ptrace() and find_new_reaper() might
803 * drop tasklist_lock and reacquire it.
804 */
805 exit_ptrace(father);
806 reaper = find_new_reaper(father);
807
808 list_for_each_entry_safe(p, n, &father->children, sibling) {
809 struct task_struct *t = p;
810 do {
811 t->real_parent = reaper;
812 if (t->parent == father) {
813 BUG_ON(t->ptrace);
814 t->parent = t->real_parent;
815 }
816 if (t->pdeath_signal)
817 group_send_sig_info(t->pdeath_signal,
818 SEND_SIG_NOINFO, t);
819 } while_each_thread(p, t);
820 reparent_leader(father, p, &dead_children);
821 }
822 write_unlock_irq(&tasklist_lock);
823
824 BUG_ON(!list_empty(&father->children));
825
826 list_for_each_entry_safe(p, n, &dead_children, sibling) {
827 list_del_init(&p->sibling);
828 release_task(p);
829 }
830}
831
832/*
833 * Send signals to all our closest relatives so that they know
834 * to properly mourn us..
835 */
836static void exit_notify(struct task_struct *tsk, int group_dead)
837{
838 bool autoreap;
839
840 /*
841 * This does two things:
842 *
843 * A. Make init inherit all the child processes
844 * B. Check to see if any process groups have become orphaned
845 * as a result of our exiting, and if they have any stopped
846 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
847 */
848 forget_original_parent(tsk);
849 exit_task_namespaces(tsk);
850
851 write_lock_irq(&tasklist_lock);
852 if (group_dead)
853 kill_orphaned_pgrp(tsk->group_leader, NULL);
854
855 if (unlikely(tsk->ptrace)) {
856 int sig = thread_group_leader(tsk) &&
857 thread_group_empty(tsk) &&
858 !ptrace_reparented(tsk) ?
859 tsk->exit_signal : SIGCHLD;
860 autoreap = do_notify_parent(tsk, sig);
861 } else if (thread_group_leader(tsk)) {
862 autoreap = thread_group_empty(tsk) &&
863 do_notify_parent(tsk, tsk->exit_signal);
864 } else {
865 autoreap = true;
866 }
867
868 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
869
870 /* mt-exec, de_thread() is waiting for group leader */
871 if (unlikely(tsk->signal->notify_count < 0))
872 wake_up_process(tsk->signal->group_exit_task);
873 write_unlock_irq(&tasklist_lock);
874
875 /* If the process is dead, release it - nobody will wait for it */
876 if (autoreap)
877 release_task(tsk);
878}
879
880#ifdef CONFIG_DEBUG_STACK_USAGE
881static void check_stack_usage(void)
882{
883 static DEFINE_SPINLOCK(low_water_lock);
884 static int lowest_to_date = THREAD_SIZE;
885 unsigned long free;
886
887 free = stack_not_used(current);
888
889 if (free >= lowest_to_date)
890 return;
891
892 spin_lock(&low_water_lock);
893 if (free < lowest_to_date) {
894 printk(KERN_WARNING "%s (%d) used greatest stack depth: "
895 "%lu bytes left\n",
896 current->comm, task_pid_nr(current), free);
897 lowest_to_date = free;
898 }
899 spin_unlock(&low_water_lock);
900}
901#else
902static inline void check_stack_usage(void) {}
903#endif
904
905void do_exit(long code)
906{
907 struct task_struct *tsk = current;
908 int group_dead;
909
910 profile_task_exit(tsk);
911
912 WARN_ON(blk_needs_flush_plug(tsk));
913
914 if (unlikely(in_interrupt()))
915 panic("Aiee, killing interrupt handler!");
916 if (unlikely(!tsk->pid))
917 panic("Attempted to kill the idle task!");
918
919 /*
920 * If do_exit is called because this processes oopsed, it's possible
921 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
922 * continuing. Amongst other possible reasons, this is to prevent
923 * mm_release()->clear_child_tid() from writing to a user-controlled
924 * kernel address.
925 */
926 set_fs(USER_DS);
927
928 ptrace_event(PTRACE_EVENT_EXIT, code);
929
930 validate_creds_for_do_exit(tsk);
931
932 /*
933 * We're taking recursive faults here in do_exit. Safest is to just
934 * leave this task alone and wait for reboot.
935 */
936 if (unlikely(tsk->flags & PF_EXITING)) {
937 printk(KERN_ALERT
938 "Fixing recursive fault but reboot is needed!\n");
939 /*
940 * We can do this unlocked here. The futex code uses
941 * this flag just to verify whether the pi state
942 * cleanup has been done or not. In the worst case it
943 * loops once more. We pretend that the cleanup was
944 * done as there is no way to return. Either the
945 * OWNER_DIED bit is set by now or we push the blocked
946 * task into the wait for ever nirwana as well.
947 */
948 tsk->flags |= PF_EXITPIDONE;
949 set_current_state(TASK_UNINTERRUPTIBLE);
950 schedule();
951 }
952
953 exit_signals(tsk); /* sets PF_EXITING */
954 /*
955 * tsk->flags are checked in the futex code to protect against
956 * an exiting task cleaning up the robust pi futexes, and in
957 * task_work_add() to avoid the race with exit_task_work().
958 */
959 smp_mb();
960 raw_spin_unlock_wait(&tsk->pi_lock);
961
962 exit_task_work(tsk);
963
964 if (unlikely(in_atomic()))
965 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
966 current->comm, task_pid_nr(current),
967 preempt_count());
968
969 acct_update_integrals(tsk);
970 /* sync mm's RSS info before statistics gathering */
971 if (tsk->mm)
972 sync_mm_rss(tsk->mm);
973 group_dead = atomic_dec_and_test(&tsk->signal->live);
974 if (group_dead) {
975 hrtimer_cancel(&tsk->signal->real_timer);
976 exit_itimers(tsk->signal);
977 if (tsk->mm)
978 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
979 }
980 acct_collect(code, group_dead);
981 if (group_dead)
982 tty_audit_exit();
983 audit_free(tsk);
984
985 tsk->exit_code = code;
986 taskstats_exit(tsk, group_dead);
987
988 exit_mm(tsk);
989
990 if (group_dead)
991 acct_process();
992 trace_sched_process_exit(tsk);
993
994 exit_sem(tsk);
995 exit_shm(tsk);
996 exit_files(tsk);
997 exit_fs(tsk);
998 check_stack_usage();
999 exit_thread();
1000
1001 /*
1002 * Flush inherited counters to the parent - before the parent
1003 * gets woken up by child-exit notifications.
1004 *
1005 * because of cgroup mode, must be called before cgroup_exit()
1006 */
1007 perf_event_exit_task(tsk);
1008
1009 cgroup_exit(tsk, 1);
1010
1011 if (group_dead)
1012 disassociate_ctty(1);
1013
1014 module_put(task_thread_info(tsk)->exec_domain->module);
1015
1016 proc_exit_connector(tsk);
1017
1018 /*
1019 * FIXME: do that only when needed, using sched_exit tracepoint
1020 */
1021 ptrace_put_breakpoints(tsk);
1022
1023 exit_notify(tsk, group_dead);
1024#ifdef CONFIG_NUMA
1025 task_lock(tsk);
1026 mpol_put(tsk->mempolicy);
1027 tsk->mempolicy = NULL;
1028 task_unlock(tsk);
1029#endif
1030#ifdef CONFIG_FUTEX
1031 if (unlikely(current->pi_state_cache))
1032 kfree(current->pi_state_cache);
1033#endif
1034 /*
1035 * Make sure we are holding no locks:
1036 */
1037 debug_check_no_locks_held(tsk);
1038 /*
1039 * We can do this unlocked here. The futex code uses this flag
1040 * just to verify whether the pi state cleanup has been done
1041 * or not. In the worst case it loops once more.
1042 */
1043 tsk->flags |= PF_EXITPIDONE;
1044
1045 if (tsk->io_context)
1046 exit_io_context(tsk);
1047
1048 if (tsk->splice_pipe)
1049 __free_pipe_info(tsk->splice_pipe);
1050
1051 validate_creds_for_do_exit(tsk);
1052
1053 preempt_disable();
1054 if (tsk->nr_dirtied)
1055 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
1056 exit_rcu();
1057
1058 /*
1059 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
1060 * when the following two conditions become true.
1061 * - There is race condition of mmap_sem (It is acquired by
1062 * exit_mm()), and
1063 * - SMI occurs before setting TASK_RUNINNG.
1064 * (or hypervisor of virtual machine switches to other guest)
1065 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
1066 *
1067 * To avoid it, we have to wait for releasing tsk->pi_lock which
1068 * is held by try_to_wake_up()
1069 */
1070 smp_mb();
1071 raw_spin_unlock_wait(&tsk->pi_lock);
1072
1073 /* causes final put_task_struct in finish_task_switch(). */
1074 tsk->state = TASK_DEAD;
1075 tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */
1076 schedule();
1077 BUG();
1078 /* Avoid "noreturn function does return". */
1079 for (;;)
1080 cpu_relax(); /* For when BUG is null */
1081}
1082
1083EXPORT_SYMBOL_GPL(do_exit);
1084
1085void complete_and_exit(struct completion *comp, long code)
1086{
1087 if (comp)
1088 complete(comp);
1089
1090 do_exit(code);
1091}
1092
1093EXPORT_SYMBOL(complete_and_exit);
1094
1095SYSCALL_DEFINE1(exit, int, error_code)
1096{
1097 do_exit((error_code&0xff)<<8);
1098}
1099
1100/*
1101 * Take down every thread in the group. This is called by fatal signals
1102 * as well as by sys_exit_group (below).
1103 */
1104void
1105do_group_exit(int exit_code)
1106{
1107 struct signal_struct *sig = current->signal;
1108
1109 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1110
1111 if (signal_group_exit(sig))
1112 exit_code = sig->group_exit_code;
1113 else if (!thread_group_empty(current)) {
1114 struct sighand_struct *const sighand = current->sighand;
1115 spin_lock_irq(&sighand->siglock);
1116 if (signal_group_exit(sig))
1117 /* Another thread got here before we took the lock. */
1118 exit_code = sig->group_exit_code;
1119 else {
1120 sig->group_exit_code = exit_code;
1121 sig->flags = SIGNAL_GROUP_EXIT;
1122 zap_other_threads(current);
1123 }
1124 spin_unlock_irq(&sighand->siglock);
1125 }
1126
1127 do_exit(exit_code);
1128 /* NOTREACHED */
1129}
1130
1131/*
1132 * this kills every thread in the thread group. Note that any externally
1133 * wait4()-ing process will get the correct exit code - even if this
1134 * thread is not the thread group leader.
1135 */
1136SYSCALL_DEFINE1(exit_group, int, error_code)
1137{
1138 do_group_exit((error_code & 0xff) << 8);
1139 /* NOTREACHED */
1140 return 0;
1141}
1142
1143struct wait_opts {
1144 enum pid_type wo_type;
1145 int wo_flags;
1146 struct pid *wo_pid;
1147
1148 struct siginfo __user *wo_info;
1149 int __user *wo_stat;
1150 struct rusage __user *wo_rusage;
1151
1152 wait_queue_t child_wait;
1153 int notask_error;
1154};
1155
1156static inline
1157struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
1158{
1159 if (type != PIDTYPE_PID)
1160 task = task->group_leader;
1161 return task->pids[type].pid;
1162}
1163
1164static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
1165{
1166 return wo->wo_type == PIDTYPE_MAX ||
1167 task_pid_type(p, wo->wo_type) == wo->wo_pid;
1168}
1169
1170static int eligible_child(struct wait_opts *wo, struct task_struct *p)
1171{
1172 if (!eligible_pid(wo, p))
1173 return 0;
1174 /* Wait for all children (clone and not) if __WALL is set;
1175 * otherwise, wait for clone children *only* if __WCLONE is
1176 * set; otherwise, wait for non-clone children *only*. (Note:
1177 * A "clone" child here is one that reports to its parent
1178 * using a signal other than SIGCHLD.) */
1179 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
1180 && !(wo->wo_flags & __WALL))
1181 return 0;
1182
1183 return 1;
1184}
1185
1186static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
1187 pid_t pid, uid_t uid, int why, int status)
1188{
1189 struct siginfo __user *infop;
1190 int retval = wo->wo_rusage
1191 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1192
1193 put_task_struct(p);
1194 infop = wo->wo_info;
1195 if (infop) {
1196 if (!retval)
1197 retval = put_user(SIGCHLD, &infop->si_signo);
1198 if (!retval)
1199 retval = put_user(0, &infop->si_errno);
1200 if (!retval)
1201 retval = put_user((short)why, &infop->si_code);
1202 if (!retval)
1203 retval = put_user(pid, &infop->si_pid);
1204 if (!retval)
1205 retval = put_user(uid, &infop->si_uid);
1206 if (!retval)
1207 retval = put_user(status, &infop->si_status);
1208 }
1209 if (!retval)
1210 retval = pid;
1211 return retval;
1212}
1213
1214/*
1215 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1216 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1217 * the lock and this task is uninteresting. If we return nonzero, we have
1218 * released the lock and the system call should return.
1219 */
1220static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1221{
1222 unsigned long state;
1223 int retval, status, traced;
1224 pid_t pid = task_pid_vnr(p);
1225 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1226 struct siginfo __user *infop;
1227
1228 if (!likely(wo->wo_flags & WEXITED))
1229 return 0;
1230
1231 if (unlikely(wo->wo_flags & WNOWAIT)) {
1232 int exit_code = p->exit_code;
1233 int why;
1234
1235 get_task_struct(p);
1236 read_unlock(&tasklist_lock);
1237 if ((exit_code & 0x7f) == 0) {
1238 why = CLD_EXITED;
1239 status = exit_code >> 8;
1240 } else {
1241 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1242 status = exit_code & 0x7f;
1243 }
1244 return wait_noreap_copyout(wo, p, pid, uid, why, status);
1245 }
1246
1247 /*
1248 * Try to move the task's state to DEAD
1249 * only one thread is allowed to do this:
1250 */
1251 state = xchg(&p->exit_state, EXIT_DEAD);
1252 if (state != EXIT_ZOMBIE) {
1253 BUG_ON(state != EXIT_DEAD);
1254 return 0;
1255 }
1256
1257 traced = ptrace_reparented(p);
1258 /*
1259 * It can be ptraced but not reparented, check
1260 * thread_group_leader() to filter out sub-threads.
1261 */
1262 if (likely(!traced) && thread_group_leader(p)) {
1263 struct signal_struct *psig;
1264 struct signal_struct *sig;
1265 unsigned long maxrss;
1266 cputime_t tgutime, tgstime;
1267
1268 /*
1269 * The resource counters for the group leader are in its
1270 * own task_struct. Those for dead threads in the group
1271 * are in its signal_struct, as are those for the child
1272 * processes it has previously reaped. All these
1273 * accumulate in the parent's signal_struct c* fields.
1274 *
1275 * We don't bother to take a lock here to protect these
1276 * p->signal fields, because they are only touched by
1277 * __exit_signal, which runs with tasklist_lock
1278 * write-locked anyway, and so is excluded here. We do
1279 * need to protect the access to parent->signal fields,
1280 * as other threads in the parent group can be right
1281 * here reaping other children at the same time.
1282 *
1283 * We use thread_group_times() to get times for the thread
1284 * group, which consolidates times for all threads in the
1285 * group including the group leader.
1286 */
1287 thread_group_times(p, &tgutime, &tgstime);
1288 spin_lock_irq(&p->real_parent->sighand->siglock);
1289 psig = p->real_parent->signal;
1290 sig = p->signal;
1291 psig->cutime += tgutime + sig->cutime;
1292 psig->cstime += tgstime + sig->cstime;
1293 psig->cgtime += p->gtime + sig->gtime + sig->cgtime;
1294 psig->cmin_flt +=
1295 p->min_flt + sig->min_flt + sig->cmin_flt;
1296 psig->cmaj_flt +=
1297 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1298 psig->cnvcsw +=
1299 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1300 psig->cnivcsw +=
1301 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1302 psig->cinblock +=
1303 task_io_get_inblock(p) +
1304 sig->inblock + sig->cinblock;
1305 psig->coublock +=
1306 task_io_get_oublock(p) +
1307 sig->oublock + sig->coublock;
1308 maxrss = max(sig->maxrss, sig->cmaxrss);
1309 if (psig->cmaxrss < maxrss)
1310 psig->cmaxrss = maxrss;
1311 task_io_accounting_add(&psig->ioac, &p->ioac);
1312 task_io_accounting_add(&psig->ioac, &sig->ioac);
1313 spin_unlock_irq(&p->real_parent->sighand->siglock);
1314 }
1315
1316 /*
1317 * Now we are sure this task is interesting, and no other
1318 * thread can reap it because we set its state to EXIT_DEAD.
1319 */
1320 read_unlock(&tasklist_lock);
1321
1322 retval = wo->wo_rusage
1323 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1324 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1325 ? p->signal->group_exit_code : p->exit_code;
1326 if (!retval && wo->wo_stat)
1327 retval = put_user(status, wo->wo_stat);
1328
1329 infop = wo->wo_info;
1330 if (!retval && infop)
1331 retval = put_user(SIGCHLD, &infop->si_signo);
1332 if (!retval && infop)
1333 retval = put_user(0, &infop->si_errno);
1334 if (!retval && infop) {
1335 int why;
1336
1337 if ((status & 0x7f) == 0) {
1338 why = CLD_EXITED;
1339 status >>= 8;
1340 } else {
1341 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1342 status &= 0x7f;
1343 }
1344 retval = put_user((short)why, &infop->si_code);
1345 if (!retval)
1346 retval = put_user(status, &infop->si_status);
1347 }
1348 if (!retval && infop)
1349 retval = put_user(pid, &infop->si_pid);
1350 if (!retval && infop)
1351 retval = put_user(uid, &infop->si_uid);
1352 if (!retval)
1353 retval = pid;
1354
1355 if (traced) {
1356 write_lock_irq(&tasklist_lock);
1357 /* We dropped tasklist, ptracer could die and untrace */
1358 ptrace_unlink(p);
1359 /*
1360 * If this is not a sub-thread, notify the parent.
1361 * If parent wants a zombie, don't release it now.
1362 */
1363 if (thread_group_leader(p) &&
1364 !do_notify_parent(p, p->exit_signal)) {
1365 p->exit_state = EXIT_ZOMBIE;
1366 p = NULL;
1367 }
1368 write_unlock_irq(&tasklist_lock);
1369 }
1370 if (p != NULL)
1371 release_task(p);
1372
1373 return retval;
1374}
1375
1376static int *task_stopped_code(struct task_struct *p, bool ptrace)
1377{
1378 if (ptrace) {
1379 if (task_is_stopped_or_traced(p) &&
1380 !(p->jobctl & JOBCTL_LISTENING))
1381 return &p->exit_code;
1382 } else {
1383 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1384 return &p->signal->group_exit_code;
1385 }
1386 return NULL;
1387}
1388
1389/**
1390 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1391 * @wo: wait options
1392 * @ptrace: is the wait for ptrace
1393 * @p: task to wait for
1394 *
1395 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1396 *
1397 * CONTEXT:
1398 * read_lock(&tasklist_lock), which is released if return value is
1399 * non-zero. Also, grabs and releases @p->sighand->siglock.
1400 *
1401 * RETURNS:
1402 * 0 if wait condition didn't exist and search for other wait conditions
1403 * should continue. Non-zero return, -errno on failure and @p's pid on
1404 * success, implies that tasklist_lock is released and wait condition
1405 * search should terminate.
1406 */
1407static int wait_task_stopped(struct wait_opts *wo,
1408 int ptrace, struct task_struct *p)
1409{
1410 struct siginfo __user *infop;
1411 int retval, exit_code, *p_code, why;
1412 uid_t uid = 0; /* unneeded, required by compiler */
1413 pid_t pid;
1414
1415 /*
1416 * Traditionally we see ptrace'd stopped tasks regardless of options.
1417 */
1418 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1419 return 0;
1420
1421 if (!task_stopped_code(p, ptrace))
1422 return 0;
1423
1424 exit_code = 0;
1425 spin_lock_irq(&p->sighand->siglock);
1426
1427 p_code = task_stopped_code(p, ptrace);
1428 if (unlikely(!p_code))
1429 goto unlock_sig;
1430
1431 exit_code = *p_code;
1432 if (!exit_code)
1433 goto unlock_sig;
1434
1435 if (!unlikely(wo->wo_flags & WNOWAIT))
1436 *p_code = 0;
1437
1438 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1439unlock_sig:
1440 spin_unlock_irq(&p->sighand->siglock);
1441 if (!exit_code)
1442 return 0;
1443
1444 /*
1445 * Now we are pretty sure this task is interesting.
1446 * Make sure it doesn't get reaped out from under us while we
1447 * give up the lock and then examine it below. We don't want to
1448 * keep holding onto the tasklist_lock while we call getrusage and
1449 * possibly take page faults for user memory.
1450 */
1451 get_task_struct(p);
1452 pid = task_pid_vnr(p);
1453 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1454 read_unlock(&tasklist_lock);
1455
1456 if (unlikely(wo->wo_flags & WNOWAIT))
1457 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
1458
1459 retval = wo->wo_rusage
1460 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1461 if (!retval && wo->wo_stat)
1462 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
1463
1464 infop = wo->wo_info;
1465 if (!retval && infop)
1466 retval = put_user(SIGCHLD, &infop->si_signo);
1467 if (!retval && infop)
1468 retval = put_user(0, &infop->si_errno);
1469 if (!retval && infop)
1470 retval = put_user((short)why, &infop->si_code);
1471 if (!retval && infop)
1472 retval = put_user(exit_code, &infop->si_status);
1473 if (!retval && infop)
1474 retval = put_user(pid, &infop->si_pid);
1475 if (!retval && infop)
1476 retval = put_user(uid, &infop->si_uid);
1477 if (!retval)
1478 retval = pid;
1479 put_task_struct(p);
1480
1481 BUG_ON(!retval);
1482 return retval;
1483}
1484
1485/*
1486 * Handle do_wait work for one task in a live, non-stopped state.
1487 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1488 * the lock and this task is uninteresting. If we return nonzero, we have
1489 * released the lock and the system call should return.
1490 */
1491static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1492{
1493 int retval;
1494 pid_t pid;
1495 uid_t uid;
1496
1497 if (!unlikely(wo->wo_flags & WCONTINUED))
1498 return 0;
1499
1500 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1501 return 0;
1502
1503 spin_lock_irq(&p->sighand->siglock);
1504 /* Re-check with the lock held. */
1505 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1506 spin_unlock_irq(&p->sighand->siglock);
1507 return 0;
1508 }
1509 if (!unlikely(wo->wo_flags & WNOWAIT))
1510 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1511 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1512 spin_unlock_irq(&p->sighand->siglock);
1513
1514 pid = task_pid_vnr(p);
1515 get_task_struct(p);
1516 read_unlock(&tasklist_lock);
1517
1518 if (!wo->wo_info) {
1519 retval = wo->wo_rusage
1520 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1521 put_task_struct(p);
1522 if (!retval && wo->wo_stat)
1523 retval = put_user(0xffff, wo->wo_stat);
1524 if (!retval)
1525 retval = pid;
1526 } else {
1527 retval = wait_noreap_copyout(wo, p, pid, uid,
1528 CLD_CONTINUED, SIGCONT);
1529 BUG_ON(retval == 0);
1530 }
1531
1532 return retval;
1533}
1534
1535/*
1536 * Consider @p for a wait by @parent.
1537 *
1538 * -ECHILD should be in ->notask_error before the first call.
1539 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1540 * Returns zero if the search for a child should continue;
1541 * then ->notask_error is 0 if @p is an eligible child,
1542 * or another error from security_task_wait(), or still -ECHILD.
1543 */
1544static int wait_consider_task(struct wait_opts *wo, int ptrace,
1545 struct task_struct *p)
1546{
1547 int ret = eligible_child(wo, p);
1548 if (!ret)
1549 return ret;
1550
1551 ret = security_task_wait(p);
1552 if (unlikely(ret < 0)) {
1553 /*
1554 * If we have not yet seen any eligible child,
1555 * then let this error code replace -ECHILD.
1556 * A permission error will give the user a clue
1557 * to look for security policy problems, rather
1558 * than for mysterious wait bugs.
1559 */
1560 if (wo->notask_error)
1561 wo->notask_error = ret;
1562 return 0;
1563 }
1564
1565 /* dead body doesn't have much to contribute */
1566 if (unlikely(p->exit_state == EXIT_DEAD)) {
1567 /*
1568 * But do not ignore this task until the tracer does
1569 * wait_task_zombie()->do_notify_parent().
1570 */
1571 if (likely(!ptrace) && unlikely(ptrace_reparented(p)))
1572 wo->notask_error = 0;
1573 return 0;
1574 }
1575
1576 /* slay zombie? */
1577 if (p->exit_state == EXIT_ZOMBIE) {
1578 /*
1579 * A zombie ptracee is only visible to its ptracer.
1580 * Notification and reaping will be cascaded to the real
1581 * parent when the ptracer detaches.
1582 */
1583 if (likely(!ptrace) && unlikely(p->ptrace)) {
1584 /* it will become visible, clear notask_error */
1585 wo->notask_error = 0;
1586 return 0;
1587 }
1588
1589 /* we don't reap group leaders with subthreads */
1590 if (!delay_group_leader(p))
1591 return wait_task_zombie(wo, p);
1592
1593 /*
1594 * Allow access to stopped/continued state via zombie by
1595 * falling through. Clearing of notask_error is complex.
1596 *
1597 * When !@ptrace:
1598 *
1599 * If WEXITED is set, notask_error should naturally be
1600 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1601 * so, if there are live subthreads, there are events to
1602 * wait for. If all subthreads are dead, it's still safe
1603 * to clear - this function will be called again in finite
1604 * amount time once all the subthreads are released and
1605 * will then return without clearing.
1606 *
1607 * When @ptrace:
1608 *
1609 * Stopped state is per-task and thus can't change once the
1610 * target task dies. Only continued and exited can happen.
1611 * Clear notask_error if WCONTINUED | WEXITED.
1612 */
1613 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1614 wo->notask_error = 0;
1615 } else {
1616 /*
1617 * If @p is ptraced by a task in its real parent's group,
1618 * hide group stop/continued state when looking at @p as
1619 * the real parent; otherwise, a single stop can be
1620 * reported twice as group and ptrace stops.
1621 *
1622 * If a ptracer wants to distinguish the two events for its
1623 * own children, it should create a separate process which
1624 * takes the role of real parent.
1625 */
1626 if (likely(!ptrace) && p->ptrace && !ptrace_reparented(p))
1627 return 0;
1628
1629 /*
1630 * @p is alive and it's gonna stop, continue or exit, so
1631 * there always is something to wait for.
1632 */
1633 wo->notask_error = 0;
1634 }
1635
1636 /*
1637 * Wait for stopped. Depending on @ptrace, different stopped state
1638 * is used and the two don't interact with each other.
1639 */
1640 ret = wait_task_stopped(wo, ptrace, p);
1641 if (ret)
1642 return ret;
1643
1644 /*
1645 * Wait for continued. There's only one continued state and the
1646 * ptracer can consume it which can confuse the real parent. Don't
1647 * use WCONTINUED from ptracer. You don't need or want it.
1648 */
1649 return wait_task_continued(wo, p);
1650}
1651
1652/*
1653 * Do the work of do_wait() for one thread in the group, @tsk.
1654 *
1655 * -ECHILD should be in ->notask_error before the first call.
1656 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1657 * Returns zero if the search for a child should continue; then
1658 * ->notask_error is 0 if there were any eligible children,
1659 * or another error from security_task_wait(), or still -ECHILD.
1660 */
1661static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1662{
1663 struct task_struct *p;
1664
1665 list_for_each_entry(p, &tsk->children, sibling) {
1666 int ret = wait_consider_task(wo, 0, p);
1667 if (ret)
1668 return ret;
1669 }
1670
1671 return 0;
1672}
1673
1674static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1675{
1676 struct task_struct *p;
1677
1678 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1679 int ret = wait_consider_task(wo, 1, p);
1680 if (ret)
1681 return ret;
1682 }
1683
1684 return 0;
1685}
1686
1687static int child_wait_callback(wait_queue_t *wait, unsigned mode,
1688 int sync, void *key)
1689{
1690 struct wait_opts *wo = container_of(wait, struct wait_opts,
1691 child_wait);
1692 struct task_struct *p = key;
1693
1694 if (!eligible_pid(wo, p))
1695 return 0;
1696
1697 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1698 return 0;
1699
1700 return default_wake_function(wait, mode, sync, key);
1701}
1702
1703void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1704{
1705 __wake_up_sync_key(&parent->signal->wait_chldexit,
1706 TASK_INTERRUPTIBLE, 1, p);
1707}
1708
1709static long do_wait(struct wait_opts *wo)
1710{
1711 struct task_struct *tsk;
1712 int retval;
1713
1714 trace_sched_process_wait(wo->wo_pid);
1715
1716 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1717 wo->child_wait.private = current;
1718 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1719repeat:
1720 /*
1721 * If there is nothing that can match our critiera just get out.
1722 * We will clear ->notask_error to zero if we see any child that
1723 * might later match our criteria, even if we are not able to reap
1724 * it yet.
1725 */
1726 wo->notask_error = -ECHILD;
1727 if ((wo->wo_type < PIDTYPE_MAX) &&
1728 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1729 goto notask;
1730
1731 set_current_state(TASK_INTERRUPTIBLE);
1732 read_lock(&tasklist_lock);
1733 tsk = current;
1734 do {
1735 retval = do_wait_thread(wo, tsk);
1736 if (retval)
1737 goto end;
1738
1739 retval = ptrace_do_wait(wo, tsk);
1740 if (retval)
1741 goto end;
1742
1743 if (wo->wo_flags & __WNOTHREAD)
1744 break;
1745 } while_each_thread(current, tsk);
1746 read_unlock(&tasklist_lock);
1747
1748notask:
1749 retval = wo->notask_error;
1750 if (!retval && !(wo->wo_flags & WNOHANG)) {
1751 retval = -ERESTARTSYS;
1752 if (!signal_pending(current)) {
1753 schedule();
1754 goto repeat;
1755 }
1756 }
1757end:
1758 __set_current_state(TASK_RUNNING);
1759 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1760 return retval;
1761}
1762
1763SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1764 infop, int, options, struct rusage __user *, ru)
1765{
1766 struct wait_opts wo;
1767 struct pid *pid = NULL;
1768 enum pid_type type;
1769 long ret;
1770
1771 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1772 return -EINVAL;
1773 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1774 return -EINVAL;
1775
1776 switch (which) {
1777 case P_ALL:
1778 type = PIDTYPE_MAX;
1779 break;
1780 case P_PID:
1781 type = PIDTYPE_PID;
1782 if (upid <= 0)
1783 return -EINVAL;
1784 break;
1785 case P_PGID:
1786 type = PIDTYPE_PGID;
1787 if (upid <= 0)
1788 return -EINVAL;
1789 break;
1790 default:
1791 return -EINVAL;
1792 }
1793
1794 if (type < PIDTYPE_MAX)
1795 pid = find_get_pid(upid);
1796
1797 wo.wo_type = type;
1798 wo.wo_pid = pid;
1799 wo.wo_flags = options;
1800 wo.wo_info = infop;
1801 wo.wo_stat = NULL;
1802 wo.wo_rusage = ru;
1803 ret = do_wait(&wo);
1804
1805 if (ret > 0) {
1806 ret = 0;
1807 } else if (infop) {
1808 /*
1809 * For a WNOHANG return, clear out all the fields
1810 * we would set so the user can easily tell the
1811 * difference.
1812 */
1813 if (!ret)
1814 ret = put_user(0, &infop->si_signo);
1815 if (!ret)
1816 ret = put_user(0, &infop->si_errno);
1817 if (!ret)
1818 ret = put_user(0, &infop->si_code);
1819 if (!ret)
1820 ret = put_user(0, &infop->si_pid);
1821 if (!ret)
1822 ret = put_user(0, &infop->si_uid);
1823 if (!ret)
1824 ret = put_user(0, &infop->si_status);
1825 }
1826
1827 put_pid(pid);
1828
1829 /* avoid REGPARM breakage on x86: */
1830 asmlinkage_protect(5, ret, which, upid, infop, options, ru);
1831 return ret;
1832}
1833
1834SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1835 int, options, struct rusage __user *, ru)
1836{
1837 struct wait_opts wo;
1838 struct pid *pid = NULL;
1839 enum pid_type type;
1840 long ret;
1841
1842 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1843 __WNOTHREAD|__WCLONE|__WALL))
1844 return -EINVAL;
1845
1846 if (upid == -1)
1847 type = PIDTYPE_MAX;
1848 else if (upid < 0) {
1849 type = PIDTYPE_PGID;
1850 pid = find_get_pid(-upid);
1851 } else if (upid == 0) {
1852 type = PIDTYPE_PGID;
1853 pid = get_task_pid(current, PIDTYPE_PGID);
1854 } else /* upid > 0 */ {
1855 type = PIDTYPE_PID;
1856 pid = find_get_pid(upid);
1857 }
1858
1859 wo.wo_type = type;
1860 wo.wo_pid = pid;
1861 wo.wo_flags = options | WEXITED;
1862 wo.wo_info = NULL;
1863 wo.wo_stat = stat_addr;
1864 wo.wo_rusage = ru;
1865 ret = do_wait(&wo);
1866 put_pid(pid);
1867
1868 /* avoid REGPARM breakage on x86: */
1869 asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
1870 return ret;
1871}
1872
1873#ifdef __ARCH_WANT_SYS_WAITPID
1874
1875/*
1876 * sys_waitpid() remains for compatibility. waitpid() should be
1877 * implemented by calling sys_wait4() from libc.a.
1878 */
1879SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1880{
1881 return sys_wait4(pid, stat_addr, options, NULL);
1882}
1883
1884#endif