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