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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// 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/task_io_accounting_ops.h>
52#include <linux/blkdev.h>
53#include <linux/task_work.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/kmsan.h>
64#include <linux/random.h>
65#include <linux/rcuwait.h>
66#include <linux/compat.h>
67#include <linux/io_uring.h>
68#include <linux/kprobes.h>
69#include <linux/rethook.h>
70#include <linux/sysfs.h>
71
72#include <linux/uaccess.h>
73#include <asm/unistd.h>
74#include <asm/mmu_context.h>
75
76/*
77 * The default value should be high enough to not crash a system that randomly
78 * crashes its kernel from time to time, but low enough to at least not permit
79 * overflowing 32-bit refcounts or the ldsem writer count.
80 */
81static unsigned int oops_limit = 10000;
82
83#ifdef CONFIG_SYSCTL
84static struct ctl_table kern_exit_table[] = {
85 {
86 .procname = "oops_limit",
87 .data = &oops_limit,
88 .maxlen = sizeof(oops_limit),
89 .mode = 0644,
90 .proc_handler = proc_douintvec,
91 },
92 { }
93};
94
95static __init int kernel_exit_sysctls_init(void)
96{
97 register_sysctl_init("kernel", kern_exit_table);
98 return 0;
99}
100late_initcall(kernel_exit_sysctls_init);
101#endif
102
103static atomic_t oops_count = ATOMIC_INIT(0);
104
105#ifdef CONFIG_SYSFS
106static ssize_t oops_count_show(struct kobject *kobj, struct kobj_attribute *attr,
107 char *page)
108{
109 return sysfs_emit(page, "%d\n", atomic_read(&oops_count));
110}
111
112static struct kobj_attribute oops_count_attr = __ATTR_RO(oops_count);
113
114static __init int kernel_exit_sysfs_init(void)
115{
116 sysfs_add_file_to_group(kernel_kobj, &oops_count_attr.attr, NULL);
117 return 0;
118}
119late_initcall(kernel_exit_sysfs_init);
120#endif
121
122static void __unhash_process(struct task_struct *p, bool group_dead)
123{
124 nr_threads--;
125 detach_pid(p, PIDTYPE_PID);
126 if (group_dead) {
127 detach_pid(p, PIDTYPE_TGID);
128 detach_pid(p, PIDTYPE_PGID);
129 detach_pid(p, PIDTYPE_SID);
130
131 list_del_rcu(&p->tasks);
132 list_del_init(&p->sibling);
133 __this_cpu_dec(process_counts);
134 }
135 list_del_rcu(&p->thread_group);
136 list_del_rcu(&p->thread_node);
137}
138
139/*
140 * This function expects the tasklist_lock write-locked.
141 */
142static void __exit_signal(struct task_struct *tsk)
143{
144 struct signal_struct *sig = tsk->signal;
145 bool group_dead = thread_group_leader(tsk);
146 struct sighand_struct *sighand;
147 struct tty_struct *tty;
148 u64 utime, stime;
149
150 sighand = rcu_dereference_check(tsk->sighand,
151 lockdep_tasklist_lock_is_held());
152 spin_lock(&sighand->siglock);
153
154#ifdef CONFIG_POSIX_TIMERS
155 posix_cpu_timers_exit(tsk);
156 if (group_dead)
157 posix_cpu_timers_exit_group(tsk);
158#endif
159
160 if (group_dead) {
161 tty = sig->tty;
162 sig->tty = NULL;
163 } else {
164 /*
165 * If there is any task waiting for the group exit
166 * then notify it:
167 */
168 if (sig->notify_count > 0 && !--sig->notify_count)
169 wake_up_process(sig->group_exec_task);
170
171 if (tsk == sig->curr_target)
172 sig->curr_target = next_thread(tsk);
173 }
174
175 add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
176 sizeof(unsigned long long));
177
178 /*
179 * Accumulate here the counters for all threads as they die. We could
180 * skip the group leader because it is the last user of signal_struct,
181 * but we want to avoid the race with thread_group_cputime() which can
182 * see the empty ->thread_head list.
183 */
184 task_cputime(tsk, &utime, &stime);
185 write_seqlock(&sig->stats_lock);
186 sig->utime += utime;
187 sig->stime += stime;
188 sig->gtime += task_gtime(tsk);
189 sig->min_flt += tsk->min_flt;
190 sig->maj_flt += tsk->maj_flt;
191 sig->nvcsw += tsk->nvcsw;
192 sig->nivcsw += tsk->nivcsw;
193 sig->inblock += task_io_get_inblock(tsk);
194 sig->oublock += task_io_get_oublock(tsk);
195 task_io_accounting_add(&sig->ioac, &tsk->ioac);
196 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
197 sig->nr_threads--;
198 __unhash_process(tsk, group_dead);
199 write_sequnlock(&sig->stats_lock);
200
201 /*
202 * Do this under ->siglock, we can race with another thread
203 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
204 */
205 flush_sigqueue(&tsk->pending);
206 tsk->sighand = NULL;
207 spin_unlock(&sighand->siglock);
208
209 __cleanup_sighand(sighand);
210 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
211 if (group_dead) {
212 flush_sigqueue(&sig->shared_pending);
213 tty_kref_put(tty);
214 }
215}
216
217static void delayed_put_task_struct(struct rcu_head *rhp)
218{
219 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
220
221 kprobe_flush_task(tsk);
222 rethook_flush_task(tsk);
223 perf_event_delayed_put(tsk);
224 trace_sched_process_free(tsk);
225 put_task_struct(tsk);
226}
227
228void put_task_struct_rcu_user(struct task_struct *task)
229{
230 if (refcount_dec_and_test(&task->rcu_users))
231 call_rcu(&task->rcu, delayed_put_task_struct);
232}
233
234void __weak release_thread(struct task_struct *dead_task)
235{
236}
237
238void release_task(struct task_struct *p)
239{
240 struct task_struct *leader;
241 struct pid *thread_pid;
242 int zap_leader;
243repeat:
244 /* don't need to get the RCU readlock here - the process is dead and
245 * can't be modifying its own credentials. But shut RCU-lockdep up */
246 rcu_read_lock();
247 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
248 rcu_read_unlock();
249
250 cgroup_release(p);
251
252 write_lock_irq(&tasklist_lock);
253 ptrace_release_task(p);
254 thread_pid = get_pid(p->thread_pid);
255 __exit_signal(p);
256
257 /*
258 * If we are the last non-leader member of the thread
259 * group, and the leader is zombie, then notify the
260 * group leader's parent process. (if it wants notification.)
261 */
262 zap_leader = 0;
263 leader = p->group_leader;
264 if (leader != p && thread_group_empty(leader)
265 && leader->exit_state == EXIT_ZOMBIE) {
266 /*
267 * If we were the last child thread and the leader has
268 * exited already, and the leader's parent ignores SIGCHLD,
269 * then we are the one who should release the leader.
270 */
271 zap_leader = do_notify_parent(leader, leader->exit_signal);
272 if (zap_leader)
273 leader->exit_state = EXIT_DEAD;
274 }
275
276 write_unlock_irq(&tasklist_lock);
277 seccomp_filter_release(p);
278 proc_flush_pid(thread_pid);
279 put_pid(thread_pid);
280 release_thread(p);
281 put_task_struct_rcu_user(p);
282
283 p = leader;
284 if (unlikely(zap_leader))
285 goto repeat;
286}
287
288int rcuwait_wake_up(struct rcuwait *w)
289{
290 int ret = 0;
291 struct task_struct *task;
292
293 rcu_read_lock();
294
295 /*
296 * Order condition vs @task, such that everything prior to the load
297 * of @task is visible. This is the condition as to why the user called
298 * rcuwait_wake() in the first place. Pairs with set_current_state()
299 * barrier (A) in rcuwait_wait_event().
300 *
301 * WAIT WAKE
302 * [S] tsk = current [S] cond = true
303 * MB (A) MB (B)
304 * [L] cond [L] tsk
305 */
306 smp_mb(); /* (B) */
307
308 task = rcu_dereference(w->task);
309 if (task)
310 ret = wake_up_process(task);
311 rcu_read_unlock();
312
313 return ret;
314}
315EXPORT_SYMBOL_GPL(rcuwait_wake_up);
316
317/*
318 * Determine if a process group is "orphaned", according to the POSIX
319 * definition in 2.2.2.52. Orphaned process groups are not to be affected
320 * by terminal-generated stop signals. Newly orphaned process groups are
321 * to receive a SIGHUP and a SIGCONT.
322 *
323 * "I ask you, have you ever known what it is to be an orphan?"
324 */
325static int will_become_orphaned_pgrp(struct pid *pgrp,
326 struct task_struct *ignored_task)
327{
328 struct task_struct *p;
329
330 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
331 if ((p == ignored_task) ||
332 (p->exit_state && thread_group_empty(p)) ||
333 is_global_init(p->real_parent))
334 continue;
335
336 if (task_pgrp(p->real_parent) != pgrp &&
337 task_session(p->real_parent) == task_session(p))
338 return 0;
339 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
340
341 return 1;
342}
343
344int is_current_pgrp_orphaned(void)
345{
346 int retval;
347
348 read_lock(&tasklist_lock);
349 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
350 read_unlock(&tasklist_lock);
351
352 return retval;
353}
354
355static bool has_stopped_jobs(struct pid *pgrp)
356{
357 struct task_struct *p;
358
359 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
360 if (p->signal->flags & SIGNAL_STOP_STOPPED)
361 return true;
362 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
363
364 return false;
365}
366
367/*
368 * Check to see if any process groups have become orphaned as
369 * a result of our exiting, and if they have any stopped jobs,
370 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
371 */
372static void
373kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
374{
375 struct pid *pgrp = task_pgrp(tsk);
376 struct task_struct *ignored_task = tsk;
377
378 if (!parent)
379 /* exit: our father is in a different pgrp than
380 * we are and we were the only connection outside.
381 */
382 parent = tsk->real_parent;
383 else
384 /* reparent: our child is in a different pgrp than
385 * we are, and it was the only connection outside.
386 */
387 ignored_task = NULL;
388
389 if (task_pgrp(parent) != pgrp &&
390 task_session(parent) == task_session(tsk) &&
391 will_become_orphaned_pgrp(pgrp, ignored_task) &&
392 has_stopped_jobs(pgrp)) {
393 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
394 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
395 }
396}
397
398static void coredump_task_exit(struct task_struct *tsk)
399{
400 struct core_state *core_state;
401
402 /*
403 * Serialize with any possible pending coredump.
404 * We must hold siglock around checking core_state
405 * and setting PF_POSTCOREDUMP. The core-inducing thread
406 * will increment ->nr_threads for each thread in the
407 * group without PF_POSTCOREDUMP set.
408 */
409 spin_lock_irq(&tsk->sighand->siglock);
410 tsk->flags |= PF_POSTCOREDUMP;
411 core_state = tsk->signal->core_state;
412 spin_unlock_irq(&tsk->sighand->siglock);
413 if (core_state) {
414 struct core_thread self;
415
416 self.task = current;
417 if (self.task->flags & PF_SIGNALED)
418 self.next = xchg(&core_state->dumper.next, &self);
419 else
420 self.task = NULL;
421 /*
422 * Implies mb(), the result of xchg() must be visible
423 * to core_state->dumper.
424 */
425 if (atomic_dec_and_test(&core_state->nr_threads))
426 complete(&core_state->startup);
427
428 for (;;) {
429 set_current_state(TASK_UNINTERRUPTIBLE|TASK_FREEZABLE);
430 if (!self.task) /* see coredump_finish() */
431 break;
432 schedule();
433 }
434 __set_current_state(TASK_RUNNING);
435 }
436}
437
438#ifdef CONFIG_MEMCG
439/*
440 * A task is exiting. If it owned this mm, find a new owner for the mm.
441 */
442void mm_update_next_owner(struct mm_struct *mm)
443{
444 struct task_struct *c, *g, *p = current;
445
446retry:
447 /*
448 * If the exiting or execing task is not the owner, it's
449 * someone else's problem.
450 */
451 if (mm->owner != p)
452 return;
453 /*
454 * The current owner is exiting/execing and there are no other
455 * candidates. Do not leave the mm pointing to a possibly
456 * freed task structure.
457 */
458 if (atomic_read(&mm->mm_users) <= 1) {
459 WRITE_ONCE(mm->owner, NULL);
460 return;
461 }
462
463 read_lock(&tasklist_lock);
464 /*
465 * Search in the children
466 */
467 list_for_each_entry(c, &p->children, sibling) {
468 if (c->mm == mm)
469 goto assign_new_owner;
470 }
471
472 /*
473 * Search in the siblings
474 */
475 list_for_each_entry(c, &p->real_parent->children, sibling) {
476 if (c->mm == mm)
477 goto assign_new_owner;
478 }
479
480 /*
481 * Search through everything else, we should not get here often.
482 */
483 for_each_process(g) {
484 if (g->flags & PF_KTHREAD)
485 continue;
486 for_each_thread(g, c) {
487 if (c->mm == mm)
488 goto assign_new_owner;
489 if (c->mm)
490 break;
491 }
492 }
493 read_unlock(&tasklist_lock);
494 /*
495 * We found no owner yet mm_users > 1: this implies that we are
496 * most likely racing with swapoff (try_to_unuse()) or /proc or
497 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
498 */
499 WRITE_ONCE(mm->owner, NULL);
500 return;
501
502assign_new_owner:
503 BUG_ON(c == p);
504 get_task_struct(c);
505 /*
506 * The task_lock protects c->mm from changing.
507 * We always want mm->owner->mm == mm
508 */
509 task_lock(c);
510 /*
511 * Delay read_unlock() till we have the task_lock()
512 * to ensure that c does not slip away underneath us
513 */
514 read_unlock(&tasklist_lock);
515 if (c->mm != mm) {
516 task_unlock(c);
517 put_task_struct(c);
518 goto retry;
519 }
520 WRITE_ONCE(mm->owner, c);
521 lru_gen_migrate_mm(mm);
522 task_unlock(c);
523 put_task_struct(c);
524}
525#endif /* CONFIG_MEMCG */
526
527/*
528 * Turn us into a lazy TLB process if we
529 * aren't already..
530 */
531static void exit_mm(void)
532{
533 struct mm_struct *mm = current->mm;
534
535 exit_mm_release(current, mm);
536 if (!mm)
537 return;
538 sync_mm_rss(mm);
539 mmap_read_lock(mm);
540 mmgrab(mm);
541 BUG_ON(mm != current->active_mm);
542 /* more a memory barrier than a real lock */
543 task_lock(current);
544 /*
545 * When a thread stops operating on an address space, the loop
546 * in membarrier_private_expedited() may not observe that
547 * tsk->mm, and the loop in membarrier_global_expedited() may
548 * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED
549 * rq->membarrier_state, so those would not issue an IPI.
550 * Membarrier requires a memory barrier after accessing
551 * user-space memory, before clearing tsk->mm or the
552 * rq->membarrier_state.
553 */
554 smp_mb__after_spinlock();
555 local_irq_disable();
556 current->mm = NULL;
557 membarrier_update_current_mm(NULL);
558 enter_lazy_tlb(mm, current);
559 local_irq_enable();
560 task_unlock(current);
561 mmap_read_unlock(mm);
562 mm_update_next_owner(mm);
563 mmput(mm);
564 if (test_thread_flag(TIF_MEMDIE))
565 exit_oom_victim();
566}
567
568static struct task_struct *find_alive_thread(struct task_struct *p)
569{
570 struct task_struct *t;
571
572 for_each_thread(p, t) {
573 if (!(t->flags & PF_EXITING))
574 return t;
575 }
576 return NULL;
577}
578
579static struct task_struct *find_child_reaper(struct task_struct *father,
580 struct list_head *dead)
581 __releases(&tasklist_lock)
582 __acquires(&tasklist_lock)
583{
584 struct pid_namespace *pid_ns = task_active_pid_ns(father);
585 struct task_struct *reaper = pid_ns->child_reaper;
586 struct task_struct *p, *n;
587
588 if (likely(reaper != father))
589 return reaper;
590
591 reaper = find_alive_thread(father);
592 if (reaper) {
593 pid_ns->child_reaper = reaper;
594 return reaper;
595 }
596
597 write_unlock_irq(&tasklist_lock);
598
599 list_for_each_entry_safe(p, n, dead, ptrace_entry) {
600 list_del_init(&p->ptrace_entry);
601 release_task(p);
602 }
603
604 zap_pid_ns_processes(pid_ns);
605 write_lock_irq(&tasklist_lock);
606
607 return father;
608}
609
610/*
611 * When we die, we re-parent all our children, and try to:
612 * 1. give them to another thread in our thread group, if such a member exists
613 * 2. give it to the first ancestor process which prctl'd itself as a
614 * child_subreaper for its children (like a service manager)
615 * 3. give it to the init process (PID 1) in our pid namespace
616 */
617static struct task_struct *find_new_reaper(struct task_struct *father,
618 struct task_struct *child_reaper)
619{
620 struct task_struct *thread, *reaper;
621
622 thread = find_alive_thread(father);
623 if (thread)
624 return thread;
625
626 if (father->signal->has_child_subreaper) {
627 unsigned int ns_level = task_pid(father)->level;
628 /*
629 * Find the first ->is_child_subreaper ancestor in our pid_ns.
630 * We can't check reaper != child_reaper to ensure we do not
631 * cross the namespaces, the exiting parent could be injected
632 * by setns() + fork().
633 * We check pid->level, this is slightly more efficient than
634 * task_active_pid_ns(reaper) != task_active_pid_ns(father).
635 */
636 for (reaper = father->real_parent;
637 task_pid(reaper)->level == ns_level;
638 reaper = reaper->real_parent) {
639 if (reaper == &init_task)
640 break;
641 if (!reaper->signal->is_child_subreaper)
642 continue;
643 thread = find_alive_thread(reaper);
644 if (thread)
645 return thread;
646 }
647 }
648
649 return child_reaper;
650}
651
652/*
653* Any that need to be release_task'd are put on the @dead list.
654 */
655static void reparent_leader(struct task_struct *father, struct task_struct *p,
656 struct list_head *dead)
657{
658 if (unlikely(p->exit_state == EXIT_DEAD))
659 return;
660
661 /* We don't want people slaying init. */
662 p->exit_signal = SIGCHLD;
663
664 /* If it has exited notify the new parent about this child's death. */
665 if (!p->ptrace &&
666 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
667 if (do_notify_parent(p, p->exit_signal)) {
668 p->exit_state = EXIT_DEAD;
669 list_add(&p->ptrace_entry, dead);
670 }
671 }
672
673 kill_orphaned_pgrp(p, father);
674}
675
676/*
677 * This does two things:
678 *
679 * A. Make init inherit all the child processes
680 * B. Check to see if any process groups have become orphaned
681 * as a result of our exiting, and if they have any stopped
682 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
683 */
684static void forget_original_parent(struct task_struct *father,
685 struct list_head *dead)
686{
687 struct task_struct *p, *t, *reaper;
688
689 if (unlikely(!list_empty(&father->ptraced)))
690 exit_ptrace(father, dead);
691
692 /* Can drop and reacquire tasklist_lock */
693 reaper = find_child_reaper(father, dead);
694 if (list_empty(&father->children))
695 return;
696
697 reaper = find_new_reaper(father, reaper);
698 list_for_each_entry(p, &father->children, sibling) {
699 for_each_thread(p, t) {
700 RCU_INIT_POINTER(t->real_parent, reaper);
701 BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father));
702 if (likely(!t->ptrace))
703 t->parent = t->real_parent;
704 if (t->pdeath_signal)
705 group_send_sig_info(t->pdeath_signal,
706 SEND_SIG_NOINFO, t,
707 PIDTYPE_TGID);
708 }
709 /*
710 * If this is a threaded reparent there is no need to
711 * notify anyone anything has happened.
712 */
713 if (!same_thread_group(reaper, father))
714 reparent_leader(father, p, dead);
715 }
716 list_splice_tail_init(&father->children, &reaper->children);
717}
718
719/*
720 * Send signals to all our closest relatives so that they know
721 * to properly mourn us..
722 */
723static void exit_notify(struct task_struct *tsk, int group_dead)
724{
725 bool autoreap;
726 struct task_struct *p, *n;
727 LIST_HEAD(dead);
728
729 write_lock_irq(&tasklist_lock);
730 forget_original_parent(tsk, &dead);
731
732 if (group_dead)
733 kill_orphaned_pgrp(tsk->group_leader, NULL);
734
735 tsk->exit_state = EXIT_ZOMBIE;
736 if (unlikely(tsk->ptrace)) {
737 int sig = thread_group_leader(tsk) &&
738 thread_group_empty(tsk) &&
739 !ptrace_reparented(tsk) ?
740 tsk->exit_signal : SIGCHLD;
741 autoreap = do_notify_parent(tsk, sig);
742 } else if (thread_group_leader(tsk)) {
743 autoreap = thread_group_empty(tsk) &&
744 do_notify_parent(tsk, tsk->exit_signal);
745 } else {
746 autoreap = true;
747 }
748
749 if (autoreap) {
750 tsk->exit_state = EXIT_DEAD;
751 list_add(&tsk->ptrace_entry, &dead);
752 }
753
754 /* mt-exec, de_thread() is waiting for group leader */
755 if (unlikely(tsk->signal->notify_count < 0))
756 wake_up_process(tsk->signal->group_exec_task);
757 write_unlock_irq(&tasklist_lock);
758
759 list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
760 list_del_init(&p->ptrace_entry);
761 release_task(p);
762 }
763}
764
765#ifdef CONFIG_DEBUG_STACK_USAGE
766static void check_stack_usage(void)
767{
768 static DEFINE_SPINLOCK(low_water_lock);
769 static int lowest_to_date = THREAD_SIZE;
770 unsigned long free;
771
772 free = stack_not_used(current);
773
774 if (free >= lowest_to_date)
775 return;
776
777 spin_lock(&low_water_lock);
778 if (free < lowest_to_date) {
779 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
780 current->comm, task_pid_nr(current), free);
781 lowest_to_date = free;
782 }
783 spin_unlock(&low_water_lock);
784}
785#else
786static inline void check_stack_usage(void) {}
787#endif
788
789static void synchronize_group_exit(struct task_struct *tsk, long code)
790{
791 struct sighand_struct *sighand = tsk->sighand;
792 struct signal_struct *signal = tsk->signal;
793
794 spin_lock_irq(&sighand->siglock);
795 signal->quick_threads--;
796 if ((signal->quick_threads == 0) &&
797 !(signal->flags & SIGNAL_GROUP_EXIT)) {
798 signal->flags = SIGNAL_GROUP_EXIT;
799 signal->group_exit_code = code;
800 signal->group_stop_count = 0;
801 }
802 spin_unlock_irq(&sighand->siglock);
803}
804
805void __noreturn do_exit(long code)
806{
807 struct task_struct *tsk = current;
808 int group_dead;
809
810 synchronize_group_exit(tsk, code);
811
812 WARN_ON(tsk->plug);
813
814 kcov_task_exit(tsk);
815 kmsan_task_exit(tsk);
816
817 coredump_task_exit(tsk);
818 ptrace_event(PTRACE_EVENT_EXIT, code);
819
820 validate_creds_for_do_exit(tsk);
821
822 io_uring_files_cancel();
823 exit_signals(tsk); /* sets PF_EXITING */
824
825 /* sync mm's RSS info before statistics gathering */
826 if (tsk->mm)
827 sync_mm_rss(tsk->mm);
828 acct_update_integrals(tsk);
829 group_dead = atomic_dec_and_test(&tsk->signal->live);
830 if (group_dead) {
831 /*
832 * If the last thread of global init has exited, panic
833 * immediately to get a useable coredump.
834 */
835 if (unlikely(is_global_init(tsk)))
836 panic("Attempted to kill init! exitcode=0x%08x\n",
837 tsk->signal->group_exit_code ?: (int)code);
838
839#ifdef CONFIG_POSIX_TIMERS
840 hrtimer_cancel(&tsk->signal->real_timer);
841 exit_itimers(tsk);
842#endif
843 if (tsk->mm)
844 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
845 }
846 acct_collect(code, group_dead);
847 if (group_dead)
848 tty_audit_exit();
849 audit_free(tsk);
850
851 tsk->exit_code = code;
852 taskstats_exit(tsk, group_dead);
853
854 exit_mm();
855
856 if (group_dead)
857 acct_process();
858 trace_sched_process_exit(tsk);
859
860 exit_sem(tsk);
861 exit_shm(tsk);
862 exit_files(tsk);
863 exit_fs(tsk);
864 if (group_dead)
865 disassociate_ctty(1);
866 exit_task_namespaces(tsk);
867 exit_task_work(tsk);
868 exit_thread(tsk);
869
870 /*
871 * Flush inherited counters to the parent - before the parent
872 * gets woken up by child-exit notifications.
873 *
874 * because of cgroup mode, must be called before cgroup_exit()
875 */
876 perf_event_exit_task(tsk);
877
878 sched_autogroup_exit_task(tsk);
879 cgroup_exit(tsk);
880
881 /*
882 * FIXME: do that only when needed, using sched_exit tracepoint
883 */
884 flush_ptrace_hw_breakpoint(tsk);
885
886 exit_tasks_rcu_start();
887 exit_notify(tsk, group_dead);
888 proc_exit_connector(tsk);
889 mpol_put_task_policy(tsk);
890#ifdef CONFIG_FUTEX
891 if (unlikely(current->pi_state_cache))
892 kfree(current->pi_state_cache);
893#endif
894 /*
895 * Make sure we are holding no locks:
896 */
897 debug_check_no_locks_held();
898
899 if (tsk->io_context)
900 exit_io_context(tsk);
901
902 if (tsk->splice_pipe)
903 free_pipe_info(tsk->splice_pipe);
904
905 if (tsk->task_frag.page)
906 put_page(tsk->task_frag.page);
907
908 validate_creds_for_do_exit(tsk);
909 exit_task_stack_account(tsk);
910
911 check_stack_usage();
912 preempt_disable();
913 if (tsk->nr_dirtied)
914 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
915 exit_rcu();
916 exit_tasks_rcu_finish();
917
918 lockdep_free_task(tsk);
919 do_task_dead();
920}
921
922void __noreturn make_task_dead(int signr)
923{
924 /*
925 * Take the task off the cpu after something catastrophic has
926 * happened.
927 *
928 * We can get here from a kernel oops, sometimes with preemption off.
929 * Start by checking for critical errors.
930 * Then fix up important state like USER_DS and preemption.
931 * Then do everything else.
932 */
933 struct task_struct *tsk = current;
934 unsigned int limit;
935
936 if (unlikely(in_interrupt()))
937 panic("Aiee, killing interrupt handler!");
938 if (unlikely(!tsk->pid))
939 panic("Attempted to kill the idle task!");
940
941 if (unlikely(in_atomic())) {
942 pr_info("note: %s[%d] exited with preempt_count %d\n",
943 current->comm, task_pid_nr(current),
944 preempt_count());
945 preempt_count_set(PREEMPT_ENABLED);
946 }
947
948 /*
949 * Every time the system oopses, if the oops happens while a reference
950 * to an object was held, the reference leaks.
951 * If the oops doesn't also leak memory, repeated oopsing can cause
952 * reference counters to wrap around (if they're not using refcount_t).
953 * This means that repeated oopsing can make unexploitable-looking bugs
954 * exploitable through repeated oopsing.
955 * To make sure this can't happen, place an upper bound on how often the
956 * kernel may oops without panic().
957 */
958 limit = READ_ONCE(oops_limit);
959 if (atomic_inc_return(&oops_count) >= limit && limit)
960 panic("Oopsed too often (kernel.oops_limit is %d)", limit);
961
962 /*
963 * We're taking recursive faults here in make_task_dead. Safest is to just
964 * leave this task alone and wait for reboot.
965 */
966 if (unlikely(tsk->flags & PF_EXITING)) {
967 pr_alert("Fixing recursive fault but reboot is needed!\n");
968 futex_exit_recursive(tsk);
969 tsk->exit_state = EXIT_DEAD;
970 refcount_inc(&tsk->rcu_users);
971 do_task_dead();
972 }
973
974 do_exit(signr);
975}
976
977SYSCALL_DEFINE1(exit, int, error_code)
978{
979 do_exit((error_code&0xff)<<8);
980}
981
982/*
983 * Take down every thread in the group. This is called by fatal signals
984 * as well as by sys_exit_group (below).
985 */
986void __noreturn
987do_group_exit(int exit_code)
988{
989 struct signal_struct *sig = current->signal;
990
991 if (sig->flags & SIGNAL_GROUP_EXIT)
992 exit_code = sig->group_exit_code;
993 else if (sig->group_exec_task)
994 exit_code = 0;
995 else {
996 struct sighand_struct *const sighand = current->sighand;
997
998 spin_lock_irq(&sighand->siglock);
999 if (sig->flags & SIGNAL_GROUP_EXIT)
1000 /* Another thread got here before we took the lock. */
1001 exit_code = sig->group_exit_code;
1002 else if (sig->group_exec_task)
1003 exit_code = 0;
1004 else {
1005 sig->group_exit_code = exit_code;
1006 sig->flags = SIGNAL_GROUP_EXIT;
1007 zap_other_threads(current);
1008 }
1009 spin_unlock_irq(&sighand->siglock);
1010 }
1011
1012 do_exit(exit_code);
1013 /* NOTREACHED */
1014}
1015
1016/*
1017 * this kills every thread in the thread group. Note that any externally
1018 * wait4()-ing process will get the correct exit code - even if this
1019 * thread is not the thread group leader.
1020 */
1021SYSCALL_DEFINE1(exit_group, int, error_code)
1022{
1023 do_group_exit((error_code & 0xff) << 8);
1024 /* NOTREACHED */
1025 return 0;
1026}
1027
1028struct waitid_info {
1029 pid_t pid;
1030 uid_t uid;
1031 int status;
1032 int cause;
1033};
1034
1035struct wait_opts {
1036 enum pid_type wo_type;
1037 int wo_flags;
1038 struct pid *wo_pid;
1039
1040 struct waitid_info *wo_info;
1041 int wo_stat;
1042 struct rusage *wo_rusage;
1043
1044 wait_queue_entry_t child_wait;
1045 int notask_error;
1046};
1047
1048static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
1049{
1050 return wo->wo_type == PIDTYPE_MAX ||
1051 task_pid_type(p, wo->wo_type) == wo->wo_pid;
1052}
1053
1054static int
1055eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
1056{
1057 if (!eligible_pid(wo, p))
1058 return 0;
1059
1060 /*
1061 * Wait for all children (clone and not) if __WALL is set or
1062 * if it is traced by us.
1063 */
1064 if (ptrace || (wo->wo_flags & __WALL))
1065 return 1;
1066
1067 /*
1068 * Otherwise, wait for clone children *only* if __WCLONE is set;
1069 * otherwise, wait for non-clone children *only*.
1070 *
1071 * Note: a "clone" child here is one that reports to its parent
1072 * using a signal other than SIGCHLD, or a non-leader thread which
1073 * we can only see if it is traced by us.
1074 */
1075 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
1076 return 0;
1077
1078 return 1;
1079}
1080
1081/*
1082 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1083 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1084 * the lock and this task is uninteresting. If we return nonzero, we have
1085 * released the lock and the system call should return.
1086 */
1087static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1088{
1089 int state, status;
1090 pid_t pid = task_pid_vnr(p);
1091 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1092 struct waitid_info *infop;
1093
1094 if (!likely(wo->wo_flags & WEXITED))
1095 return 0;
1096
1097 if (unlikely(wo->wo_flags & WNOWAIT)) {
1098 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1099 ? p->signal->group_exit_code : p->exit_code;
1100 get_task_struct(p);
1101 read_unlock(&tasklist_lock);
1102 sched_annotate_sleep();
1103 if (wo->wo_rusage)
1104 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1105 put_task_struct(p);
1106 goto out_info;
1107 }
1108 /*
1109 * Move the task's state to DEAD/TRACE, only one thread can do this.
1110 */
1111 state = (ptrace_reparented(p) && thread_group_leader(p)) ?
1112 EXIT_TRACE : EXIT_DEAD;
1113 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1114 return 0;
1115 /*
1116 * We own this thread, nobody else can reap it.
1117 */
1118 read_unlock(&tasklist_lock);
1119 sched_annotate_sleep();
1120
1121 /*
1122 * Check thread_group_leader() to exclude the traced sub-threads.
1123 */
1124 if (state == EXIT_DEAD && thread_group_leader(p)) {
1125 struct signal_struct *sig = p->signal;
1126 struct signal_struct *psig = current->signal;
1127 unsigned long maxrss;
1128 u64 tgutime, tgstime;
1129
1130 /*
1131 * The resource counters for the group leader are in its
1132 * own task_struct. Those for dead threads in the group
1133 * are in its signal_struct, as are those for the child
1134 * processes it has previously reaped. All these
1135 * accumulate in the parent's signal_struct c* fields.
1136 *
1137 * We don't bother to take a lock here to protect these
1138 * p->signal fields because the whole thread group is dead
1139 * and nobody can change them.
1140 *
1141 * psig->stats_lock also protects us from our sub-threads
1142 * which can reap other children at the same time. Until
1143 * we change k_getrusage()-like users to rely on this lock
1144 * we have to take ->siglock as well.
1145 *
1146 * We use thread_group_cputime_adjusted() to get times for
1147 * the thread group, which consolidates times for all threads
1148 * in the group including the group leader.
1149 */
1150 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1151 spin_lock_irq(¤t->sighand->siglock);
1152 write_seqlock(&psig->stats_lock);
1153 psig->cutime += tgutime + sig->cutime;
1154 psig->cstime += tgstime + sig->cstime;
1155 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1156 psig->cmin_flt +=
1157 p->min_flt + sig->min_flt + sig->cmin_flt;
1158 psig->cmaj_flt +=
1159 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1160 psig->cnvcsw +=
1161 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1162 psig->cnivcsw +=
1163 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1164 psig->cinblock +=
1165 task_io_get_inblock(p) +
1166 sig->inblock + sig->cinblock;
1167 psig->coublock +=
1168 task_io_get_oublock(p) +
1169 sig->oublock + sig->coublock;
1170 maxrss = max(sig->maxrss, sig->cmaxrss);
1171 if (psig->cmaxrss < maxrss)
1172 psig->cmaxrss = maxrss;
1173 task_io_accounting_add(&psig->ioac, &p->ioac);
1174 task_io_accounting_add(&psig->ioac, &sig->ioac);
1175 write_sequnlock(&psig->stats_lock);
1176 spin_unlock_irq(¤t->sighand->siglock);
1177 }
1178
1179 if (wo->wo_rusage)
1180 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1181 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1182 ? p->signal->group_exit_code : p->exit_code;
1183 wo->wo_stat = status;
1184
1185 if (state == EXIT_TRACE) {
1186 write_lock_irq(&tasklist_lock);
1187 /* We dropped tasklist, ptracer could die and untrace */
1188 ptrace_unlink(p);
1189
1190 /* If parent wants a zombie, don't release it now */
1191 state = EXIT_ZOMBIE;
1192 if (do_notify_parent(p, p->exit_signal))
1193 state = EXIT_DEAD;
1194 p->exit_state = state;
1195 write_unlock_irq(&tasklist_lock);
1196 }
1197 if (state == EXIT_DEAD)
1198 release_task(p);
1199
1200out_info:
1201 infop = wo->wo_info;
1202 if (infop) {
1203 if ((status & 0x7f) == 0) {
1204 infop->cause = CLD_EXITED;
1205 infop->status = status >> 8;
1206 } else {
1207 infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1208 infop->status = status & 0x7f;
1209 }
1210 infop->pid = pid;
1211 infop->uid = uid;
1212 }
1213
1214 return pid;
1215}
1216
1217static int *task_stopped_code(struct task_struct *p, bool ptrace)
1218{
1219 if (ptrace) {
1220 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING))
1221 return &p->exit_code;
1222 } else {
1223 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1224 return &p->signal->group_exit_code;
1225 }
1226 return NULL;
1227}
1228
1229/**
1230 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1231 * @wo: wait options
1232 * @ptrace: is the wait for ptrace
1233 * @p: task to wait for
1234 *
1235 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1236 *
1237 * CONTEXT:
1238 * read_lock(&tasklist_lock), which is released if return value is
1239 * non-zero. Also, grabs and releases @p->sighand->siglock.
1240 *
1241 * RETURNS:
1242 * 0 if wait condition didn't exist and search for other wait conditions
1243 * should continue. Non-zero return, -errno on failure and @p's pid on
1244 * success, implies that tasklist_lock is released and wait condition
1245 * search should terminate.
1246 */
1247static int wait_task_stopped(struct wait_opts *wo,
1248 int ptrace, struct task_struct *p)
1249{
1250 struct waitid_info *infop;
1251 int exit_code, *p_code, why;
1252 uid_t uid = 0; /* unneeded, required by compiler */
1253 pid_t pid;
1254
1255 /*
1256 * Traditionally we see ptrace'd stopped tasks regardless of options.
1257 */
1258 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1259 return 0;
1260
1261 if (!task_stopped_code(p, ptrace))
1262 return 0;
1263
1264 exit_code = 0;
1265 spin_lock_irq(&p->sighand->siglock);
1266
1267 p_code = task_stopped_code(p, ptrace);
1268 if (unlikely(!p_code))
1269 goto unlock_sig;
1270
1271 exit_code = *p_code;
1272 if (!exit_code)
1273 goto unlock_sig;
1274
1275 if (!unlikely(wo->wo_flags & WNOWAIT))
1276 *p_code = 0;
1277
1278 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1279unlock_sig:
1280 spin_unlock_irq(&p->sighand->siglock);
1281 if (!exit_code)
1282 return 0;
1283
1284 /*
1285 * Now we are pretty sure this task is interesting.
1286 * Make sure it doesn't get reaped out from under us while we
1287 * give up the lock and then examine it below. We don't want to
1288 * keep holding onto the tasklist_lock while we call getrusage and
1289 * possibly take page faults for user memory.
1290 */
1291 get_task_struct(p);
1292 pid = task_pid_vnr(p);
1293 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1294 read_unlock(&tasklist_lock);
1295 sched_annotate_sleep();
1296 if (wo->wo_rusage)
1297 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1298 put_task_struct(p);
1299
1300 if (likely(!(wo->wo_flags & WNOWAIT)))
1301 wo->wo_stat = (exit_code << 8) | 0x7f;
1302
1303 infop = wo->wo_info;
1304 if (infop) {
1305 infop->cause = why;
1306 infop->status = exit_code;
1307 infop->pid = pid;
1308 infop->uid = uid;
1309 }
1310 return pid;
1311}
1312
1313/*
1314 * Handle do_wait work for one task in a live, non-stopped state.
1315 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1316 * the lock and this task is uninteresting. If we return nonzero, we have
1317 * released the lock and the system call should return.
1318 */
1319static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1320{
1321 struct waitid_info *infop;
1322 pid_t pid;
1323 uid_t uid;
1324
1325 if (!unlikely(wo->wo_flags & WCONTINUED))
1326 return 0;
1327
1328 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1329 return 0;
1330
1331 spin_lock_irq(&p->sighand->siglock);
1332 /* Re-check with the lock held. */
1333 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1334 spin_unlock_irq(&p->sighand->siglock);
1335 return 0;
1336 }
1337 if (!unlikely(wo->wo_flags & WNOWAIT))
1338 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1339 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1340 spin_unlock_irq(&p->sighand->siglock);
1341
1342 pid = task_pid_vnr(p);
1343 get_task_struct(p);
1344 read_unlock(&tasklist_lock);
1345 sched_annotate_sleep();
1346 if (wo->wo_rusage)
1347 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1348 put_task_struct(p);
1349
1350 infop = wo->wo_info;
1351 if (!infop) {
1352 wo->wo_stat = 0xffff;
1353 } else {
1354 infop->cause = CLD_CONTINUED;
1355 infop->pid = pid;
1356 infop->uid = uid;
1357 infop->status = SIGCONT;
1358 }
1359 return pid;
1360}
1361
1362/*
1363 * Consider @p for a wait by @parent.
1364 *
1365 * -ECHILD should be in ->notask_error before the first call.
1366 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1367 * Returns zero if the search for a child should continue;
1368 * then ->notask_error is 0 if @p is an eligible child,
1369 * or still -ECHILD.
1370 */
1371static int wait_consider_task(struct wait_opts *wo, int ptrace,
1372 struct task_struct *p)
1373{
1374 /*
1375 * We can race with wait_task_zombie() from another thread.
1376 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1377 * can't confuse the checks below.
1378 */
1379 int exit_state = READ_ONCE(p->exit_state);
1380 int ret;
1381
1382 if (unlikely(exit_state == EXIT_DEAD))
1383 return 0;
1384
1385 ret = eligible_child(wo, ptrace, p);
1386 if (!ret)
1387 return ret;
1388
1389 if (unlikely(exit_state == EXIT_TRACE)) {
1390 /*
1391 * ptrace == 0 means we are the natural parent. In this case
1392 * we should clear notask_error, debugger will notify us.
1393 */
1394 if (likely(!ptrace))
1395 wo->notask_error = 0;
1396 return 0;
1397 }
1398
1399 if (likely(!ptrace) && unlikely(p->ptrace)) {
1400 /*
1401 * If it is traced by its real parent's group, just pretend
1402 * the caller is ptrace_do_wait() and reap this child if it
1403 * is zombie.
1404 *
1405 * This also hides group stop state from real parent; otherwise
1406 * a single stop can be reported twice as group and ptrace stop.
1407 * If a ptracer wants to distinguish these two events for its
1408 * own children it should create a separate process which takes
1409 * the role of real parent.
1410 */
1411 if (!ptrace_reparented(p))
1412 ptrace = 1;
1413 }
1414
1415 /* slay zombie? */
1416 if (exit_state == EXIT_ZOMBIE) {
1417 /* we don't reap group leaders with subthreads */
1418 if (!delay_group_leader(p)) {
1419 /*
1420 * A zombie ptracee is only visible to its ptracer.
1421 * Notification and reaping will be cascaded to the
1422 * real parent when the ptracer detaches.
1423 */
1424 if (unlikely(ptrace) || likely(!p->ptrace))
1425 return wait_task_zombie(wo, p);
1426 }
1427
1428 /*
1429 * Allow access to stopped/continued state via zombie by
1430 * falling through. Clearing of notask_error is complex.
1431 *
1432 * When !@ptrace:
1433 *
1434 * If WEXITED is set, notask_error should naturally be
1435 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1436 * so, if there are live subthreads, there are events to
1437 * wait for. If all subthreads are dead, it's still safe
1438 * to clear - this function will be called again in finite
1439 * amount time once all the subthreads are released and
1440 * will then return without clearing.
1441 *
1442 * When @ptrace:
1443 *
1444 * Stopped state is per-task and thus can't change once the
1445 * target task dies. Only continued and exited can happen.
1446 * Clear notask_error if WCONTINUED | WEXITED.
1447 */
1448 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1449 wo->notask_error = 0;
1450 } else {
1451 /*
1452 * @p is alive and it's gonna stop, continue or exit, so
1453 * there always is something to wait for.
1454 */
1455 wo->notask_error = 0;
1456 }
1457
1458 /*
1459 * Wait for stopped. Depending on @ptrace, different stopped state
1460 * is used and the two don't interact with each other.
1461 */
1462 ret = wait_task_stopped(wo, ptrace, p);
1463 if (ret)
1464 return ret;
1465
1466 /*
1467 * Wait for continued. There's only one continued state and the
1468 * ptracer can consume it which can confuse the real parent. Don't
1469 * use WCONTINUED from ptracer. You don't need or want it.
1470 */
1471 return wait_task_continued(wo, p);
1472}
1473
1474/*
1475 * Do the work of do_wait() for one thread in the group, @tsk.
1476 *
1477 * -ECHILD should be in ->notask_error before the first call.
1478 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1479 * Returns zero if the search for a child should continue; then
1480 * ->notask_error is 0 if there were any eligible children,
1481 * or still -ECHILD.
1482 */
1483static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1484{
1485 struct task_struct *p;
1486
1487 list_for_each_entry(p, &tsk->children, sibling) {
1488 int ret = wait_consider_task(wo, 0, p);
1489
1490 if (ret)
1491 return ret;
1492 }
1493
1494 return 0;
1495}
1496
1497static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1498{
1499 struct task_struct *p;
1500
1501 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1502 int ret = wait_consider_task(wo, 1, p);
1503
1504 if (ret)
1505 return ret;
1506 }
1507
1508 return 0;
1509}
1510
1511static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode,
1512 int sync, void *key)
1513{
1514 struct wait_opts *wo = container_of(wait, struct wait_opts,
1515 child_wait);
1516 struct task_struct *p = key;
1517
1518 if (!eligible_pid(wo, p))
1519 return 0;
1520
1521 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1522 return 0;
1523
1524 return default_wake_function(wait, mode, sync, key);
1525}
1526
1527void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1528{
1529 __wake_up_sync_key(&parent->signal->wait_chldexit,
1530 TASK_INTERRUPTIBLE, p);
1531}
1532
1533static bool is_effectively_child(struct wait_opts *wo, bool ptrace,
1534 struct task_struct *target)
1535{
1536 struct task_struct *parent =
1537 !ptrace ? target->real_parent : target->parent;
1538
1539 return current == parent || (!(wo->wo_flags & __WNOTHREAD) &&
1540 same_thread_group(current, parent));
1541}
1542
1543/*
1544 * Optimization for waiting on PIDTYPE_PID. No need to iterate through child
1545 * and tracee lists to find the target task.
1546 */
1547static int do_wait_pid(struct wait_opts *wo)
1548{
1549 bool ptrace;
1550 struct task_struct *target;
1551 int retval;
1552
1553 ptrace = false;
1554 target = pid_task(wo->wo_pid, PIDTYPE_TGID);
1555 if (target && is_effectively_child(wo, ptrace, target)) {
1556 retval = wait_consider_task(wo, ptrace, target);
1557 if (retval)
1558 return retval;
1559 }
1560
1561 ptrace = true;
1562 target = pid_task(wo->wo_pid, PIDTYPE_PID);
1563 if (target && target->ptrace &&
1564 is_effectively_child(wo, ptrace, target)) {
1565 retval = wait_consider_task(wo, ptrace, target);
1566 if (retval)
1567 return retval;
1568 }
1569
1570 return 0;
1571}
1572
1573static long do_wait(struct wait_opts *wo)
1574{
1575 int retval;
1576
1577 trace_sched_process_wait(wo->wo_pid);
1578
1579 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1580 wo->child_wait.private = current;
1581 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1582repeat:
1583 /*
1584 * If there is nothing that can match our criteria, just get out.
1585 * We will clear ->notask_error to zero if we see any child that
1586 * might later match our criteria, even if we are not able to reap
1587 * it yet.
1588 */
1589 wo->notask_error = -ECHILD;
1590 if ((wo->wo_type < PIDTYPE_MAX) &&
1591 (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type)))
1592 goto notask;
1593
1594 set_current_state(TASK_INTERRUPTIBLE);
1595 read_lock(&tasklist_lock);
1596
1597 if (wo->wo_type == PIDTYPE_PID) {
1598 retval = do_wait_pid(wo);
1599 if (retval)
1600 goto end;
1601 } else {
1602 struct task_struct *tsk = current;
1603
1604 do {
1605 retval = do_wait_thread(wo, tsk);
1606 if (retval)
1607 goto end;
1608
1609 retval = ptrace_do_wait(wo, tsk);
1610 if (retval)
1611 goto end;
1612
1613 if (wo->wo_flags & __WNOTHREAD)
1614 break;
1615 } while_each_thread(current, tsk);
1616 }
1617 read_unlock(&tasklist_lock);
1618
1619notask:
1620 retval = wo->notask_error;
1621 if (!retval && !(wo->wo_flags & WNOHANG)) {
1622 retval = -ERESTARTSYS;
1623 if (!signal_pending(current)) {
1624 schedule();
1625 goto repeat;
1626 }
1627 }
1628end:
1629 __set_current_state(TASK_RUNNING);
1630 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1631 return retval;
1632}
1633
1634static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
1635 int options, struct rusage *ru)
1636{
1637 struct wait_opts wo;
1638 struct pid *pid = NULL;
1639 enum pid_type type;
1640 long ret;
1641 unsigned int f_flags = 0;
1642
1643 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
1644 __WNOTHREAD|__WCLONE|__WALL))
1645 return -EINVAL;
1646 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1647 return -EINVAL;
1648
1649 switch (which) {
1650 case P_ALL:
1651 type = PIDTYPE_MAX;
1652 break;
1653 case P_PID:
1654 type = PIDTYPE_PID;
1655 if (upid <= 0)
1656 return -EINVAL;
1657
1658 pid = find_get_pid(upid);
1659 break;
1660 case P_PGID:
1661 type = PIDTYPE_PGID;
1662 if (upid < 0)
1663 return -EINVAL;
1664
1665 if (upid)
1666 pid = find_get_pid(upid);
1667 else
1668 pid = get_task_pid(current, PIDTYPE_PGID);
1669 break;
1670 case P_PIDFD:
1671 type = PIDTYPE_PID;
1672 if (upid < 0)
1673 return -EINVAL;
1674
1675 pid = pidfd_get_pid(upid, &f_flags);
1676 if (IS_ERR(pid))
1677 return PTR_ERR(pid);
1678
1679 break;
1680 default:
1681 return -EINVAL;
1682 }
1683
1684 wo.wo_type = type;
1685 wo.wo_pid = pid;
1686 wo.wo_flags = options;
1687 wo.wo_info = infop;
1688 wo.wo_rusage = ru;
1689 if (f_flags & O_NONBLOCK)
1690 wo.wo_flags |= WNOHANG;
1691
1692 ret = do_wait(&wo);
1693 if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK))
1694 ret = -EAGAIN;
1695
1696 put_pid(pid);
1697 return ret;
1698}
1699
1700SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1701 infop, int, options, struct rusage __user *, ru)
1702{
1703 struct rusage r;
1704 struct waitid_info info = {.status = 0};
1705 long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
1706 int signo = 0;
1707
1708 if (err > 0) {
1709 signo = SIGCHLD;
1710 err = 0;
1711 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1712 return -EFAULT;
1713 }
1714 if (!infop)
1715 return err;
1716
1717 if (!user_write_access_begin(infop, sizeof(*infop)))
1718 return -EFAULT;
1719
1720 unsafe_put_user(signo, &infop->si_signo, Efault);
1721 unsafe_put_user(0, &infop->si_errno, Efault);
1722 unsafe_put_user(info.cause, &infop->si_code, Efault);
1723 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1724 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1725 unsafe_put_user(info.status, &infop->si_status, Efault);
1726 user_write_access_end();
1727 return err;
1728Efault:
1729 user_write_access_end();
1730 return -EFAULT;
1731}
1732
1733long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
1734 struct rusage *ru)
1735{
1736 struct wait_opts wo;
1737 struct pid *pid = NULL;
1738 enum pid_type type;
1739 long ret;
1740
1741 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1742 __WNOTHREAD|__WCLONE|__WALL))
1743 return -EINVAL;
1744
1745 /* -INT_MIN is not defined */
1746 if (upid == INT_MIN)
1747 return -ESRCH;
1748
1749 if (upid == -1)
1750 type = PIDTYPE_MAX;
1751 else if (upid < 0) {
1752 type = PIDTYPE_PGID;
1753 pid = find_get_pid(-upid);
1754 } else if (upid == 0) {
1755 type = PIDTYPE_PGID;
1756 pid = get_task_pid(current, PIDTYPE_PGID);
1757 } else /* upid > 0 */ {
1758 type = PIDTYPE_PID;
1759 pid = find_get_pid(upid);
1760 }
1761
1762 wo.wo_type = type;
1763 wo.wo_pid = pid;
1764 wo.wo_flags = options | WEXITED;
1765 wo.wo_info = NULL;
1766 wo.wo_stat = 0;
1767 wo.wo_rusage = ru;
1768 ret = do_wait(&wo);
1769 put_pid(pid);
1770 if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
1771 ret = -EFAULT;
1772
1773 return ret;
1774}
1775
1776int kernel_wait(pid_t pid, int *stat)
1777{
1778 struct wait_opts wo = {
1779 .wo_type = PIDTYPE_PID,
1780 .wo_pid = find_get_pid(pid),
1781 .wo_flags = WEXITED,
1782 };
1783 int ret;
1784
1785 ret = do_wait(&wo);
1786 if (ret > 0 && wo.wo_stat)
1787 *stat = wo.wo_stat;
1788 put_pid(wo.wo_pid);
1789 return ret;
1790}
1791
1792SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1793 int, options, struct rusage __user *, ru)
1794{
1795 struct rusage r;
1796 long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL);
1797
1798 if (err > 0) {
1799 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1800 return -EFAULT;
1801 }
1802 return err;
1803}
1804
1805#ifdef __ARCH_WANT_SYS_WAITPID
1806
1807/*
1808 * sys_waitpid() remains for compatibility. waitpid() should be
1809 * implemented by calling sys_wait4() from libc.a.
1810 */
1811SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1812{
1813 return kernel_wait4(pid, stat_addr, options, NULL);
1814}
1815
1816#endif
1817
1818#ifdef CONFIG_COMPAT
1819COMPAT_SYSCALL_DEFINE4(wait4,
1820 compat_pid_t, pid,
1821 compat_uint_t __user *, stat_addr,
1822 int, options,
1823 struct compat_rusage __user *, ru)
1824{
1825 struct rusage r;
1826 long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL);
1827 if (err > 0) {
1828 if (ru && put_compat_rusage(&r, ru))
1829 return -EFAULT;
1830 }
1831 return err;
1832}
1833
1834COMPAT_SYSCALL_DEFINE5(waitid,
1835 int, which, compat_pid_t, pid,
1836 struct compat_siginfo __user *, infop, int, options,
1837 struct compat_rusage __user *, uru)
1838{
1839 struct rusage ru;
1840 struct waitid_info info = {.status = 0};
1841 long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);
1842 int signo = 0;
1843 if (err > 0) {
1844 signo = SIGCHLD;
1845 err = 0;
1846 if (uru) {
1847 /* kernel_waitid() overwrites everything in ru */
1848 if (COMPAT_USE_64BIT_TIME)
1849 err = copy_to_user(uru, &ru, sizeof(ru));
1850 else
1851 err = put_compat_rusage(&ru, uru);
1852 if (err)
1853 return -EFAULT;
1854 }
1855 }
1856
1857 if (!infop)
1858 return err;
1859
1860 if (!user_write_access_begin(infop, sizeof(*infop)))
1861 return -EFAULT;
1862
1863 unsafe_put_user(signo, &infop->si_signo, Efault);
1864 unsafe_put_user(0, &infop->si_errno, Efault);
1865 unsafe_put_user(info.cause, &infop->si_code, Efault);
1866 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1867 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1868 unsafe_put_user(info.status, &infop->si_status, Efault);
1869 user_write_access_end();
1870 return err;
1871Efault:
1872 user_write_access_end();
1873 return -EFAULT;
1874}
1875#endif
1876
1877/**
1878 * thread_group_exited - check that a thread group has exited
1879 * @pid: tgid of thread group to be checked.
1880 *
1881 * Test if the thread group represented by tgid has exited (all
1882 * threads are zombies, dead or completely gone).
1883 *
1884 * Return: true if the thread group has exited. false otherwise.
1885 */
1886bool thread_group_exited(struct pid *pid)
1887{
1888 struct task_struct *task;
1889 bool exited;
1890
1891 rcu_read_lock();
1892 task = pid_task(pid, PIDTYPE_PID);
1893 exited = !task ||
1894 (READ_ONCE(task->exit_state) && thread_group_empty(task));
1895 rcu_read_unlock();
1896
1897 return exited;
1898}
1899EXPORT_SYMBOL(thread_group_exited);
1900
1901__weak void abort(void)
1902{
1903 BUG();
1904
1905 /* if that doesn't kill us, halt */
1906 panic("Oops failed to kill thread");
1907}
1908EXPORT_SYMBOL(abort);