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1/*
2 * linux/kernel/exit.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7#include <linux/mm.h>
8#include <linux/slab.h>
9#include <linux/interrupt.h>
10#include <linux/module.h>
11#include <linux/capability.h>
12#include <linux/completion.h>
13#include <linux/personality.h>
14#include <linux/tty.h>
15#include <linux/iocontext.h>
16#include <linux/key.h>
17#include <linux/security.h>
18#include <linux/cpu.h>
19#include <linux/acct.h>
20#include <linux/tsacct_kern.h>
21#include <linux/file.h>
22#include <linux/fdtable.h>
23#include <linux/freezer.h>
24#include <linux/binfmts.h>
25#include <linux/nsproxy.h>
26#include <linux/pid_namespace.h>
27#include <linux/ptrace.h>
28#include <linux/profile.h>
29#include <linux/mount.h>
30#include <linux/proc_fs.h>
31#include <linux/kthread.h>
32#include <linux/mempolicy.h>
33#include <linux/taskstats_kern.h>
34#include <linux/delayacct.h>
35#include <linux/cgroup.h>
36#include <linux/syscalls.h>
37#include <linux/signal.h>
38#include <linux/posix-timers.h>
39#include <linux/cn_proc.h>
40#include <linux/mutex.h>
41#include <linux/futex.h>
42#include <linux/pipe_fs_i.h>
43#include <linux/audit.h> /* for audit_free() */
44#include <linux/resource.h>
45#include <linux/blkdev.h>
46#include <linux/task_io_accounting_ops.h>
47#include <linux/tracehook.h>
48#include <linux/fs_struct.h>
49#include <linux/init_task.h>
50#include <linux/perf_event.h>
51#include <trace/events/sched.h>
52#include <linux/hw_breakpoint.h>
53#include <linux/oom.h>
54#include <linux/writeback.h>
55#include <linux/shm.h>
56
57#include <asm/uaccess.h>
58#include <asm/unistd.h>
59#include <asm/pgtable.h>
60#include <asm/mmu_context.h>
61
62static void exit_mm(struct task_struct * tsk);
63
64static void __unhash_process(struct task_struct *p, bool group_dead)
65{
66 nr_threads--;
67 detach_pid(p, PIDTYPE_PID);
68 if (group_dead) {
69 detach_pid(p, PIDTYPE_PGID);
70 detach_pid(p, PIDTYPE_SID);
71
72 list_del_rcu(&p->tasks);
73 list_del_init(&p->sibling);
74 __this_cpu_dec(process_counts);
75 }
76 list_del_rcu(&p->thread_group);
77 list_del_rcu(&p->thread_node);
78}
79
80/*
81 * This function expects the tasklist_lock write-locked.
82 */
83static void __exit_signal(struct task_struct *tsk)
84{
85 struct signal_struct *sig = tsk->signal;
86 bool group_dead = thread_group_leader(tsk);
87 struct sighand_struct *sighand;
88 struct tty_struct *uninitialized_var(tty);
89 cputime_t utime, stime;
90
91 sighand = rcu_dereference_check(tsk->sighand,
92 lockdep_tasklist_lock_is_held());
93 spin_lock(&sighand->siglock);
94
95 posix_cpu_timers_exit(tsk);
96 if (group_dead) {
97 posix_cpu_timers_exit_group(tsk);
98 tty = sig->tty;
99 sig->tty = NULL;
100 } else {
101 /*
102 * This can only happen if the caller is de_thread().
103 * FIXME: this is the temporary hack, we should teach
104 * posix-cpu-timers to handle this case correctly.
105 */
106 if (unlikely(has_group_leader_pid(tsk)))
107 posix_cpu_timers_exit_group(tsk);
108
109 /*
110 * If there is any task waiting for the group exit
111 * then notify it:
112 */
113 if (sig->notify_count > 0 && !--sig->notify_count)
114 wake_up_process(sig->group_exit_task);
115
116 if (tsk == sig->curr_target)
117 sig->curr_target = next_thread(tsk);
118 /*
119 * Accumulate here the counters for all threads but the
120 * group leader as they die, so they can be added into
121 * the process-wide totals when those are taken.
122 * The group leader stays around as a zombie as long
123 * as there are other threads. When it gets reaped,
124 * the exit.c code will add its counts into these totals.
125 * We won't ever get here for the group leader, since it
126 * will have been the last reference on the signal_struct.
127 */
128 task_cputime(tsk, &utime, &stime);
129 sig->utime += utime;
130 sig->stime += stime;
131 sig->gtime += task_gtime(tsk);
132 sig->min_flt += tsk->min_flt;
133 sig->maj_flt += tsk->maj_flt;
134 sig->nvcsw += tsk->nvcsw;
135 sig->nivcsw += tsk->nivcsw;
136 sig->inblock += task_io_get_inblock(tsk);
137 sig->oublock += task_io_get_oublock(tsk);
138 task_io_accounting_add(&sig->ioac, &tsk->ioac);
139 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
140 }
141
142 sig->nr_threads--;
143 __unhash_process(tsk, group_dead);
144
145 /*
146 * Do this under ->siglock, we can race with another thread
147 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
148 */
149 flush_sigqueue(&tsk->pending);
150 tsk->sighand = NULL;
151 spin_unlock(&sighand->siglock);
152
153 __cleanup_sighand(sighand);
154 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
155 if (group_dead) {
156 flush_sigqueue(&sig->shared_pending);
157 tty_kref_put(tty);
158 }
159}
160
161static void delayed_put_task_struct(struct rcu_head *rhp)
162{
163 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
164
165 perf_event_delayed_put(tsk);
166 trace_sched_process_free(tsk);
167 put_task_struct(tsk);
168}
169
170
171void release_task(struct task_struct * p)
172{
173 struct task_struct *leader;
174 int zap_leader;
175repeat:
176 /* don't need to get the RCU readlock here - the process is dead and
177 * can't be modifying its own credentials. But shut RCU-lockdep up */
178 rcu_read_lock();
179 atomic_dec(&__task_cred(p)->user->processes);
180 rcu_read_unlock();
181
182 proc_flush_task(p);
183
184 write_lock_irq(&tasklist_lock);
185 ptrace_release_task(p);
186 __exit_signal(p);
187
188 /*
189 * If we are the last non-leader member of the thread
190 * group, and the leader is zombie, then notify the
191 * group leader's parent process. (if it wants notification.)
192 */
193 zap_leader = 0;
194 leader = p->group_leader;
195 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
196 /*
197 * If we were the last child thread and the leader has
198 * exited already, and the leader's parent ignores SIGCHLD,
199 * then we are the one who should release the leader.
200 */
201 zap_leader = do_notify_parent(leader, leader->exit_signal);
202 if (zap_leader)
203 leader->exit_state = EXIT_DEAD;
204 }
205
206 write_unlock_irq(&tasklist_lock);
207 release_thread(p);
208 call_rcu(&p->rcu, delayed_put_task_struct);
209
210 p = leader;
211 if (unlikely(zap_leader))
212 goto repeat;
213}
214
215/*
216 * This checks not only the pgrp, but falls back on the pid if no
217 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
218 * without this...
219 *
220 * The caller must hold rcu lock or the tasklist lock.
221 */
222struct pid *session_of_pgrp(struct pid *pgrp)
223{
224 struct task_struct *p;
225 struct pid *sid = NULL;
226
227 p = pid_task(pgrp, PIDTYPE_PGID);
228 if (p == NULL)
229 p = pid_task(pgrp, PIDTYPE_PID);
230 if (p != NULL)
231 sid = task_session(p);
232
233 return sid;
234}
235
236/*
237 * Determine if a process group is "orphaned", according to the POSIX
238 * definition in 2.2.2.52. Orphaned process groups are not to be affected
239 * by terminal-generated stop signals. Newly orphaned process groups are
240 * to receive a SIGHUP and a SIGCONT.
241 *
242 * "I ask you, have you ever known what it is to be an orphan?"
243 */
244static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
245{
246 struct task_struct *p;
247
248 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
249 if ((p == ignored_task) ||
250 (p->exit_state && thread_group_empty(p)) ||
251 is_global_init(p->real_parent))
252 continue;
253
254 if (task_pgrp(p->real_parent) != pgrp &&
255 task_session(p->real_parent) == task_session(p))
256 return 0;
257 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
258
259 return 1;
260}
261
262int is_current_pgrp_orphaned(void)
263{
264 int retval;
265
266 read_lock(&tasklist_lock);
267 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
268 read_unlock(&tasklist_lock);
269
270 return retval;
271}
272
273static bool has_stopped_jobs(struct pid *pgrp)
274{
275 struct task_struct *p;
276
277 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
278 if (p->signal->flags & SIGNAL_STOP_STOPPED)
279 return true;
280 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
281
282 return false;
283}
284
285/*
286 * Check to see if any process groups have become orphaned as
287 * a result of our exiting, and if they have any stopped jobs,
288 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
289 */
290static void
291kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
292{
293 struct pid *pgrp = task_pgrp(tsk);
294 struct task_struct *ignored_task = tsk;
295
296 if (!parent)
297 /* exit: our father is in a different pgrp than
298 * we are and we were the only connection outside.
299 */
300 parent = tsk->real_parent;
301 else
302 /* reparent: our child is in a different pgrp than
303 * we are, and it was the only connection outside.
304 */
305 ignored_task = NULL;
306
307 if (task_pgrp(parent) != pgrp &&
308 task_session(parent) == task_session(tsk) &&
309 will_become_orphaned_pgrp(pgrp, ignored_task) &&
310 has_stopped_jobs(pgrp)) {
311 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
312 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
313 }
314}
315
316/*
317 * Let kernel threads use this to say that they allow a certain signal.
318 * Must not be used if kthread was cloned with CLONE_SIGHAND.
319 */
320int allow_signal(int sig)
321{
322 if (!valid_signal(sig) || sig < 1)
323 return -EINVAL;
324
325 spin_lock_irq(¤t->sighand->siglock);
326 /* This is only needed for daemonize()'ed kthreads */
327 sigdelset(¤t->blocked, sig);
328 /*
329 * Kernel threads handle their own signals. Let the signal code
330 * know it'll be handled, so that they don't get converted to
331 * SIGKILL or just silently dropped.
332 */
333 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
334 recalc_sigpending();
335 spin_unlock_irq(¤t->sighand->siglock);
336 return 0;
337}
338
339EXPORT_SYMBOL(allow_signal);
340
341int disallow_signal(int sig)
342{
343 if (!valid_signal(sig) || sig < 1)
344 return -EINVAL;
345
346 spin_lock_irq(¤t->sighand->siglock);
347 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
348 recalc_sigpending();
349 spin_unlock_irq(¤t->sighand->siglock);
350 return 0;
351}
352
353EXPORT_SYMBOL(disallow_signal);
354
355#ifdef CONFIG_MM_OWNER
356/*
357 * A task is exiting. If it owned this mm, find a new owner for the mm.
358 */
359void mm_update_next_owner(struct mm_struct *mm)
360{
361 struct task_struct *c, *g, *p = current;
362
363retry:
364 /*
365 * If the exiting or execing task is not the owner, it's
366 * someone else's problem.
367 */
368 if (mm->owner != p)
369 return;
370 /*
371 * The current owner is exiting/execing and there are no other
372 * candidates. Do not leave the mm pointing to a possibly
373 * freed task structure.
374 */
375 if (atomic_read(&mm->mm_users) <= 1) {
376 mm->owner = NULL;
377 return;
378 }
379
380 read_lock(&tasklist_lock);
381 /*
382 * Search in the children
383 */
384 list_for_each_entry(c, &p->children, sibling) {
385 if (c->mm == mm)
386 goto assign_new_owner;
387 }
388
389 /*
390 * Search in the siblings
391 */
392 list_for_each_entry(c, &p->real_parent->children, sibling) {
393 if (c->mm == mm)
394 goto assign_new_owner;
395 }
396
397 /*
398 * Search through everything else. We should not get
399 * here often
400 */
401 do_each_thread(g, c) {
402 if (c->mm == mm)
403 goto assign_new_owner;
404 } while_each_thread(g, c);
405
406 read_unlock(&tasklist_lock);
407 /*
408 * We found no owner yet mm_users > 1: this implies that we are
409 * most likely racing with swapoff (try_to_unuse()) or /proc or
410 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
411 */
412 mm->owner = NULL;
413 return;
414
415assign_new_owner:
416 BUG_ON(c == p);
417 get_task_struct(c);
418 /*
419 * The task_lock protects c->mm from changing.
420 * We always want mm->owner->mm == mm
421 */
422 task_lock(c);
423 /*
424 * Delay read_unlock() till we have the task_lock()
425 * to ensure that c does not slip away underneath us
426 */
427 read_unlock(&tasklist_lock);
428 if (c->mm != mm) {
429 task_unlock(c);
430 put_task_struct(c);
431 goto retry;
432 }
433 mm->owner = c;
434 task_unlock(c);
435 put_task_struct(c);
436}
437#endif /* CONFIG_MM_OWNER */
438
439/*
440 * Turn us into a lazy TLB process if we
441 * aren't already..
442 */
443static void exit_mm(struct task_struct * tsk)
444{
445 struct mm_struct *mm = tsk->mm;
446 struct core_state *core_state;
447
448 mm_release(tsk, mm);
449 if (!mm)
450 return;
451 sync_mm_rss(mm);
452 /*
453 * Serialize with any possible pending coredump.
454 * We must hold mmap_sem around checking core_state
455 * and clearing tsk->mm. The core-inducing thread
456 * will increment ->nr_threads for each thread in the
457 * group with ->mm != NULL.
458 */
459 down_read(&mm->mmap_sem);
460 core_state = mm->core_state;
461 if (core_state) {
462 struct core_thread self;
463 up_read(&mm->mmap_sem);
464
465 self.task = tsk;
466 self.next = xchg(&core_state->dumper.next, &self);
467 /*
468 * Implies mb(), the result of xchg() must be visible
469 * to core_state->dumper.
470 */
471 if (atomic_dec_and_test(&core_state->nr_threads))
472 complete(&core_state->startup);
473
474 for (;;) {
475 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
476 if (!self.task) /* see coredump_finish() */
477 break;
478 freezable_schedule();
479 }
480 __set_task_state(tsk, TASK_RUNNING);
481 down_read(&mm->mmap_sem);
482 }
483 atomic_inc(&mm->mm_count);
484 BUG_ON(mm != tsk->active_mm);
485 /* more a memory barrier than a real lock */
486 task_lock(tsk);
487 tsk->mm = NULL;
488 up_read(&mm->mmap_sem);
489 enter_lazy_tlb(mm, current);
490 task_unlock(tsk);
491 mm_update_next_owner(mm);
492 mmput(mm);
493}
494
495/*
496 * When we die, we re-parent all our children, and try to:
497 * 1. give them to another thread in our thread group, if such a member exists
498 * 2. give it to the first ancestor process which prctl'd itself as a
499 * child_subreaper for its children (like a service manager)
500 * 3. give it to the init process (PID 1) in our pid namespace
501 */
502static struct task_struct *find_new_reaper(struct task_struct *father)
503 __releases(&tasklist_lock)
504 __acquires(&tasklist_lock)
505{
506 struct pid_namespace *pid_ns = task_active_pid_ns(father);
507 struct task_struct *thread;
508
509 thread = father;
510 while_each_thread(father, thread) {
511 if (thread->flags & PF_EXITING)
512 continue;
513 if (unlikely(pid_ns->child_reaper == father))
514 pid_ns->child_reaper = thread;
515 return thread;
516 }
517
518 if (unlikely(pid_ns->child_reaper == father)) {
519 write_unlock_irq(&tasklist_lock);
520 if (unlikely(pid_ns == &init_pid_ns)) {
521 panic("Attempted to kill init! exitcode=0x%08x\n",
522 father->signal->group_exit_code ?:
523 father->exit_code);
524 }
525
526 zap_pid_ns_processes(pid_ns);
527 write_lock_irq(&tasklist_lock);
528 } else if (father->signal->has_child_subreaper) {
529 struct task_struct *reaper;
530
531 /*
532 * Find the first ancestor marked as child_subreaper.
533 * Note that the code below checks same_thread_group(reaper,
534 * pid_ns->child_reaper). This is what we need to DTRT in a
535 * PID namespace. However we still need the check above, see
536 * http://marc.info/?l=linux-kernel&m=131385460420380
537 */
538 for (reaper = father->real_parent;
539 reaper != &init_task;
540 reaper = reaper->real_parent) {
541 if (same_thread_group(reaper, pid_ns->child_reaper))
542 break;
543 if (!reaper->signal->is_child_subreaper)
544 continue;
545 thread = reaper;
546 do {
547 if (!(thread->flags & PF_EXITING))
548 return reaper;
549 } while_each_thread(reaper, thread);
550 }
551 }
552
553 return pid_ns->child_reaper;
554}
555
556/*
557* Any that need to be release_task'd are put on the @dead list.
558 */
559static void reparent_leader(struct task_struct *father, struct task_struct *p,
560 struct list_head *dead)
561{
562 list_move_tail(&p->sibling, &p->real_parent->children);
563
564 if (p->exit_state == EXIT_DEAD)
565 return;
566 /*
567 * If this is a threaded reparent there is no need to
568 * notify anyone anything has happened.
569 */
570 if (same_thread_group(p->real_parent, father))
571 return;
572
573 /* We don't want people slaying init. */
574 p->exit_signal = SIGCHLD;
575
576 /* If it has exited notify the new parent about this child's death. */
577 if (!p->ptrace &&
578 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
579 if (do_notify_parent(p, p->exit_signal)) {
580 p->exit_state = EXIT_DEAD;
581 list_move_tail(&p->sibling, dead);
582 }
583 }
584
585 kill_orphaned_pgrp(p, father);
586}
587
588static void forget_original_parent(struct task_struct *father)
589{
590 struct task_struct *p, *n, *reaper;
591 LIST_HEAD(dead_children);
592
593 write_lock_irq(&tasklist_lock);
594 /*
595 * Note that exit_ptrace() and find_new_reaper() might
596 * drop tasklist_lock and reacquire it.
597 */
598 exit_ptrace(father);
599 reaper = find_new_reaper(father);
600
601 list_for_each_entry_safe(p, n, &father->children, sibling) {
602 struct task_struct *t = p;
603 do {
604 t->real_parent = reaper;
605 if (t->parent == father) {
606 BUG_ON(t->ptrace);
607 t->parent = t->real_parent;
608 }
609 if (t->pdeath_signal)
610 group_send_sig_info(t->pdeath_signal,
611 SEND_SIG_NOINFO, t);
612 } while_each_thread(p, t);
613 reparent_leader(father, p, &dead_children);
614 }
615 write_unlock_irq(&tasklist_lock);
616
617 BUG_ON(!list_empty(&father->children));
618
619 list_for_each_entry_safe(p, n, &dead_children, sibling) {
620 list_del_init(&p->sibling);
621 release_task(p);
622 }
623}
624
625/*
626 * Send signals to all our closest relatives so that they know
627 * to properly mourn us..
628 */
629static void exit_notify(struct task_struct *tsk, int group_dead)
630{
631 bool autoreap;
632
633 /*
634 * This does two things:
635 *
636 * A. Make init inherit all the child processes
637 * B. Check to see if any process groups have become orphaned
638 * as a result of our exiting, and if they have any stopped
639 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
640 */
641 forget_original_parent(tsk);
642
643 write_lock_irq(&tasklist_lock);
644 if (group_dead)
645 kill_orphaned_pgrp(tsk->group_leader, NULL);
646
647 if (unlikely(tsk->ptrace)) {
648 int sig = thread_group_leader(tsk) &&
649 thread_group_empty(tsk) &&
650 !ptrace_reparented(tsk) ?
651 tsk->exit_signal : SIGCHLD;
652 autoreap = do_notify_parent(tsk, sig);
653 } else if (thread_group_leader(tsk)) {
654 autoreap = thread_group_empty(tsk) &&
655 do_notify_parent(tsk, tsk->exit_signal);
656 } else {
657 autoreap = true;
658 }
659
660 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
661
662 /* mt-exec, de_thread() is waiting for group leader */
663 if (unlikely(tsk->signal->notify_count < 0))
664 wake_up_process(tsk->signal->group_exit_task);
665 write_unlock_irq(&tasklist_lock);
666
667 /* If the process is dead, release it - nobody will wait for it */
668 if (autoreap)
669 release_task(tsk);
670}
671
672#ifdef CONFIG_DEBUG_STACK_USAGE
673static void check_stack_usage(void)
674{
675 static DEFINE_SPINLOCK(low_water_lock);
676 static int lowest_to_date = THREAD_SIZE;
677 unsigned long free;
678
679 free = stack_not_used(current);
680
681 if (free >= lowest_to_date)
682 return;
683
684 spin_lock(&low_water_lock);
685 if (free < lowest_to_date) {
686 printk(KERN_WARNING "%s (%d) used greatest stack depth: "
687 "%lu bytes left\n",
688 current->comm, task_pid_nr(current), free);
689 lowest_to_date = free;
690 }
691 spin_unlock(&low_water_lock);
692}
693#else
694static inline void check_stack_usage(void) {}
695#endif
696
697void do_exit(long code)
698{
699 struct task_struct *tsk = current;
700 int group_dead;
701
702 profile_task_exit(tsk);
703
704 WARN_ON(blk_needs_flush_plug(tsk));
705
706 if (unlikely(in_interrupt()))
707 panic("Aiee, killing interrupt handler!");
708 if (unlikely(!tsk->pid))
709 panic("Attempted to kill the idle task!");
710
711 /*
712 * If do_exit is called because this processes oopsed, it's possible
713 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
714 * continuing. Amongst other possible reasons, this is to prevent
715 * mm_release()->clear_child_tid() from writing to a user-controlled
716 * kernel address.
717 */
718 set_fs(USER_DS);
719
720 ptrace_event(PTRACE_EVENT_EXIT, code);
721
722 validate_creds_for_do_exit(tsk);
723
724 /*
725 * We're taking recursive faults here in do_exit. Safest is to just
726 * leave this task alone and wait for reboot.
727 */
728 if (unlikely(tsk->flags & PF_EXITING)) {
729 printk(KERN_ALERT
730 "Fixing recursive fault but reboot is needed!\n");
731 /*
732 * We can do this unlocked here. The futex code uses
733 * this flag just to verify whether the pi state
734 * cleanup has been done or not. In the worst case it
735 * loops once more. We pretend that the cleanup was
736 * done as there is no way to return. Either the
737 * OWNER_DIED bit is set by now or we push the blocked
738 * task into the wait for ever nirwana as well.
739 */
740 tsk->flags |= PF_EXITPIDONE;
741 set_current_state(TASK_UNINTERRUPTIBLE);
742 schedule();
743 }
744
745 exit_signals(tsk); /* sets PF_EXITING */
746 /*
747 * tsk->flags are checked in the futex code to protect against
748 * an exiting task cleaning up the robust pi futexes.
749 */
750 smp_mb();
751 raw_spin_unlock_wait(&tsk->pi_lock);
752
753 if (unlikely(in_atomic()))
754 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
755 current->comm, task_pid_nr(current),
756 preempt_count());
757
758 acct_update_integrals(tsk);
759 /* sync mm's RSS info before statistics gathering */
760 if (tsk->mm)
761 sync_mm_rss(tsk->mm);
762 group_dead = atomic_dec_and_test(&tsk->signal->live);
763 if (group_dead) {
764 hrtimer_cancel(&tsk->signal->real_timer);
765 exit_itimers(tsk->signal);
766 if (tsk->mm)
767 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
768 }
769 acct_collect(code, group_dead);
770 if (group_dead)
771 tty_audit_exit();
772 audit_free(tsk);
773
774 tsk->exit_code = code;
775 taskstats_exit(tsk, group_dead);
776
777 exit_mm(tsk);
778
779 if (group_dead)
780 acct_process();
781 trace_sched_process_exit(tsk);
782
783 exit_sem(tsk);
784 exit_shm(tsk);
785 exit_files(tsk);
786 exit_fs(tsk);
787 if (group_dead)
788 disassociate_ctty(1);
789 exit_task_namespaces(tsk);
790 exit_task_work(tsk);
791 exit_thread();
792
793 /*
794 * Flush inherited counters to the parent - before the parent
795 * gets woken up by child-exit notifications.
796 *
797 * because of cgroup mode, must be called before cgroup_exit()
798 */
799 perf_event_exit_task(tsk);
800
801 cgroup_exit(tsk);
802
803 module_put(task_thread_info(tsk)->exec_domain->module);
804
805 /*
806 * FIXME: do that only when needed, using sched_exit tracepoint
807 */
808 flush_ptrace_hw_breakpoint(tsk);
809
810 exit_notify(tsk, group_dead);
811 proc_exit_connector(tsk);
812#ifdef CONFIG_NUMA
813 task_lock(tsk);
814 mpol_put(tsk->mempolicy);
815 tsk->mempolicy = NULL;
816 task_unlock(tsk);
817#endif
818#ifdef CONFIG_FUTEX
819 if (unlikely(current->pi_state_cache))
820 kfree(current->pi_state_cache);
821#endif
822 /*
823 * Make sure we are holding no locks:
824 */
825 debug_check_no_locks_held();
826 /*
827 * We can do this unlocked here. The futex code uses this flag
828 * just to verify whether the pi state cleanup has been done
829 * or not. In the worst case it loops once more.
830 */
831 tsk->flags |= PF_EXITPIDONE;
832
833 if (tsk->io_context)
834 exit_io_context(tsk);
835
836 if (tsk->splice_pipe)
837 free_pipe_info(tsk->splice_pipe);
838
839 if (tsk->task_frag.page)
840 put_page(tsk->task_frag.page);
841
842 validate_creds_for_do_exit(tsk);
843
844 check_stack_usage();
845 preempt_disable();
846 if (tsk->nr_dirtied)
847 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
848 exit_rcu();
849
850 /*
851 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
852 * when the following two conditions become true.
853 * - There is race condition of mmap_sem (It is acquired by
854 * exit_mm()), and
855 * - SMI occurs before setting TASK_RUNINNG.
856 * (or hypervisor of virtual machine switches to other guest)
857 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
858 *
859 * To avoid it, we have to wait for releasing tsk->pi_lock which
860 * is held by try_to_wake_up()
861 */
862 smp_mb();
863 raw_spin_unlock_wait(&tsk->pi_lock);
864
865 /* causes final put_task_struct in finish_task_switch(). */
866 tsk->state = TASK_DEAD;
867 tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */
868 schedule();
869 BUG();
870 /* Avoid "noreturn function does return". */
871 for (;;)
872 cpu_relax(); /* For when BUG is null */
873}
874
875EXPORT_SYMBOL_GPL(do_exit);
876
877void complete_and_exit(struct completion *comp, long code)
878{
879 if (comp)
880 complete(comp);
881
882 do_exit(code);
883}
884
885EXPORT_SYMBOL(complete_and_exit);
886
887SYSCALL_DEFINE1(exit, int, error_code)
888{
889 do_exit((error_code&0xff)<<8);
890}
891
892/*
893 * Take down every thread in the group. This is called by fatal signals
894 * as well as by sys_exit_group (below).
895 */
896void
897do_group_exit(int exit_code)
898{
899 struct signal_struct *sig = current->signal;
900
901 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
902
903 if (signal_group_exit(sig))
904 exit_code = sig->group_exit_code;
905 else if (!thread_group_empty(current)) {
906 struct sighand_struct *const sighand = current->sighand;
907 spin_lock_irq(&sighand->siglock);
908 if (signal_group_exit(sig))
909 /* Another thread got here before we took the lock. */
910 exit_code = sig->group_exit_code;
911 else {
912 sig->group_exit_code = exit_code;
913 sig->flags = SIGNAL_GROUP_EXIT;
914 zap_other_threads(current);
915 }
916 spin_unlock_irq(&sighand->siglock);
917 }
918
919 do_exit(exit_code);
920 /* NOTREACHED */
921}
922
923/*
924 * this kills every thread in the thread group. Note that any externally
925 * wait4()-ing process will get the correct exit code - even if this
926 * thread is not the thread group leader.
927 */
928SYSCALL_DEFINE1(exit_group, int, error_code)
929{
930 do_group_exit((error_code & 0xff) << 8);
931 /* NOTREACHED */
932 return 0;
933}
934
935struct wait_opts {
936 enum pid_type wo_type;
937 int wo_flags;
938 struct pid *wo_pid;
939
940 struct siginfo __user *wo_info;
941 int __user *wo_stat;
942 struct rusage __user *wo_rusage;
943
944 wait_queue_t child_wait;
945 int notask_error;
946};
947
948static inline
949struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
950{
951 if (type != PIDTYPE_PID)
952 task = task->group_leader;
953 return task->pids[type].pid;
954}
955
956static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
957{
958 return wo->wo_type == PIDTYPE_MAX ||
959 task_pid_type(p, wo->wo_type) == wo->wo_pid;
960}
961
962static int eligible_child(struct wait_opts *wo, struct task_struct *p)
963{
964 if (!eligible_pid(wo, p))
965 return 0;
966 /* Wait for all children (clone and not) if __WALL is set;
967 * otherwise, wait for clone children *only* if __WCLONE is
968 * set; otherwise, wait for non-clone children *only*. (Note:
969 * A "clone" child here is one that reports to its parent
970 * using a signal other than SIGCHLD.) */
971 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
972 && !(wo->wo_flags & __WALL))
973 return 0;
974
975 return 1;
976}
977
978static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
979 pid_t pid, uid_t uid, int why, int status)
980{
981 struct siginfo __user *infop;
982 int retval = wo->wo_rusage
983 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
984
985 put_task_struct(p);
986 infop = wo->wo_info;
987 if (infop) {
988 if (!retval)
989 retval = put_user(SIGCHLD, &infop->si_signo);
990 if (!retval)
991 retval = put_user(0, &infop->si_errno);
992 if (!retval)
993 retval = put_user((short)why, &infop->si_code);
994 if (!retval)
995 retval = put_user(pid, &infop->si_pid);
996 if (!retval)
997 retval = put_user(uid, &infop->si_uid);
998 if (!retval)
999 retval = put_user(status, &infop->si_status);
1000 }
1001 if (!retval)
1002 retval = pid;
1003 return retval;
1004}
1005
1006/*
1007 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1008 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1009 * the lock and this task is uninteresting. If we return nonzero, we have
1010 * released the lock and the system call should return.
1011 */
1012static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1013{
1014 unsigned long state;
1015 int retval, status, traced;
1016 pid_t pid = task_pid_vnr(p);
1017 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1018 struct siginfo __user *infop;
1019
1020 if (!likely(wo->wo_flags & WEXITED))
1021 return 0;
1022
1023 if (unlikely(wo->wo_flags & WNOWAIT)) {
1024 int exit_code = p->exit_code;
1025 int why;
1026
1027 get_task_struct(p);
1028 read_unlock(&tasklist_lock);
1029 if ((exit_code & 0x7f) == 0) {
1030 why = CLD_EXITED;
1031 status = exit_code >> 8;
1032 } else {
1033 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1034 status = exit_code & 0x7f;
1035 }
1036 return wait_noreap_copyout(wo, p, pid, uid, why, status);
1037 }
1038
1039 traced = ptrace_reparented(p);
1040 /*
1041 * Move the task's state to DEAD/TRACE, only one thread can do this.
1042 */
1043 state = traced && thread_group_leader(p) ? EXIT_TRACE : EXIT_DEAD;
1044 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1045 return 0;
1046 /*
1047 * It can be ptraced but not reparented, check
1048 * thread_group_leader() to filter out sub-threads.
1049 */
1050 if (likely(!traced) && thread_group_leader(p)) {
1051 struct signal_struct *psig;
1052 struct signal_struct *sig;
1053 unsigned long maxrss;
1054 cputime_t tgutime, tgstime;
1055
1056 /*
1057 * The resource counters for the group leader are in its
1058 * own task_struct. Those for dead threads in the group
1059 * are in its signal_struct, as are those for the child
1060 * processes it has previously reaped. All these
1061 * accumulate in the parent's signal_struct c* fields.
1062 *
1063 * We don't bother to take a lock here to protect these
1064 * p->signal fields, because they are only touched by
1065 * __exit_signal, which runs with tasklist_lock
1066 * write-locked anyway, and so is excluded here. We do
1067 * need to protect the access to parent->signal fields,
1068 * as other threads in the parent group can be right
1069 * here reaping other children at the same time.
1070 *
1071 * We use thread_group_cputime_adjusted() to get times for the thread
1072 * group, which consolidates times for all threads in the
1073 * group including the group leader.
1074 */
1075 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1076 spin_lock_irq(&p->real_parent->sighand->siglock);
1077 psig = p->real_parent->signal;
1078 sig = p->signal;
1079 psig->cutime += tgutime + sig->cutime;
1080 psig->cstime += tgstime + sig->cstime;
1081 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1082 psig->cmin_flt +=
1083 p->min_flt + sig->min_flt + sig->cmin_flt;
1084 psig->cmaj_flt +=
1085 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1086 psig->cnvcsw +=
1087 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1088 psig->cnivcsw +=
1089 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1090 psig->cinblock +=
1091 task_io_get_inblock(p) +
1092 sig->inblock + sig->cinblock;
1093 psig->coublock +=
1094 task_io_get_oublock(p) +
1095 sig->oublock + sig->coublock;
1096 maxrss = max(sig->maxrss, sig->cmaxrss);
1097 if (psig->cmaxrss < maxrss)
1098 psig->cmaxrss = maxrss;
1099 task_io_accounting_add(&psig->ioac, &p->ioac);
1100 task_io_accounting_add(&psig->ioac, &sig->ioac);
1101 spin_unlock_irq(&p->real_parent->sighand->siglock);
1102 }
1103
1104 /*
1105 * Now we are sure this task is interesting, and no other
1106 * thread can reap it because we its state == DEAD/TRACE.
1107 */
1108 read_unlock(&tasklist_lock);
1109
1110 retval = wo->wo_rusage
1111 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1112 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1113 ? p->signal->group_exit_code : p->exit_code;
1114 if (!retval && wo->wo_stat)
1115 retval = put_user(status, wo->wo_stat);
1116
1117 infop = wo->wo_info;
1118 if (!retval && infop)
1119 retval = put_user(SIGCHLD, &infop->si_signo);
1120 if (!retval && infop)
1121 retval = put_user(0, &infop->si_errno);
1122 if (!retval && infop) {
1123 int why;
1124
1125 if ((status & 0x7f) == 0) {
1126 why = CLD_EXITED;
1127 status >>= 8;
1128 } else {
1129 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1130 status &= 0x7f;
1131 }
1132 retval = put_user((short)why, &infop->si_code);
1133 if (!retval)
1134 retval = put_user(status, &infop->si_status);
1135 }
1136 if (!retval && infop)
1137 retval = put_user(pid, &infop->si_pid);
1138 if (!retval && infop)
1139 retval = put_user(uid, &infop->si_uid);
1140 if (!retval)
1141 retval = pid;
1142
1143 if (state == EXIT_TRACE) {
1144 write_lock_irq(&tasklist_lock);
1145 /* We dropped tasklist, ptracer could die and untrace */
1146 ptrace_unlink(p);
1147
1148 /* If parent wants a zombie, don't release it now */
1149 state = EXIT_ZOMBIE;
1150 if (do_notify_parent(p, p->exit_signal))
1151 state = EXIT_DEAD;
1152 p->exit_state = state;
1153 write_unlock_irq(&tasklist_lock);
1154 }
1155 if (state == EXIT_DEAD)
1156 release_task(p);
1157
1158 return retval;
1159}
1160
1161static int *task_stopped_code(struct task_struct *p, bool ptrace)
1162{
1163 if (ptrace) {
1164 if (task_is_stopped_or_traced(p) &&
1165 !(p->jobctl & JOBCTL_LISTENING))
1166 return &p->exit_code;
1167 } else {
1168 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1169 return &p->signal->group_exit_code;
1170 }
1171 return NULL;
1172}
1173
1174/**
1175 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1176 * @wo: wait options
1177 * @ptrace: is the wait for ptrace
1178 * @p: task to wait for
1179 *
1180 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1181 *
1182 * CONTEXT:
1183 * read_lock(&tasklist_lock), which is released if return value is
1184 * non-zero. Also, grabs and releases @p->sighand->siglock.
1185 *
1186 * RETURNS:
1187 * 0 if wait condition didn't exist and search for other wait conditions
1188 * should continue. Non-zero return, -errno on failure and @p's pid on
1189 * success, implies that tasklist_lock is released and wait condition
1190 * search should terminate.
1191 */
1192static int wait_task_stopped(struct wait_opts *wo,
1193 int ptrace, struct task_struct *p)
1194{
1195 struct siginfo __user *infop;
1196 int retval, exit_code, *p_code, why;
1197 uid_t uid = 0; /* unneeded, required by compiler */
1198 pid_t pid;
1199
1200 /*
1201 * Traditionally we see ptrace'd stopped tasks regardless of options.
1202 */
1203 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1204 return 0;
1205
1206 if (!task_stopped_code(p, ptrace))
1207 return 0;
1208
1209 exit_code = 0;
1210 spin_lock_irq(&p->sighand->siglock);
1211
1212 p_code = task_stopped_code(p, ptrace);
1213 if (unlikely(!p_code))
1214 goto unlock_sig;
1215
1216 exit_code = *p_code;
1217 if (!exit_code)
1218 goto unlock_sig;
1219
1220 if (!unlikely(wo->wo_flags & WNOWAIT))
1221 *p_code = 0;
1222
1223 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1224unlock_sig:
1225 spin_unlock_irq(&p->sighand->siglock);
1226 if (!exit_code)
1227 return 0;
1228
1229 /*
1230 * Now we are pretty sure this task is interesting.
1231 * Make sure it doesn't get reaped out from under us while we
1232 * give up the lock and then examine it below. We don't want to
1233 * keep holding onto the tasklist_lock while we call getrusage and
1234 * possibly take page faults for user memory.
1235 */
1236 get_task_struct(p);
1237 pid = task_pid_vnr(p);
1238 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1239 read_unlock(&tasklist_lock);
1240
1241 if (unlikely(wo->wo_flags & WNOWAIT))
1242 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
1243
1244 retval = wo->wo_rusage
1245 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1246 if (!retval && wo->wo_stat)
1247 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
1248
1249 infop = wo->wo_info;
1250 if (!retval && infop)
1251 retval = put_user(SIGCHLD, &infop->si_signo);
1252 if (!retval && infop)
1253 retval = put_user(0, &infop->si_errno);
1254 if (!retval && infop)
1255 retval = put_user((short)why, &infop->si_code);
1256 if (!retval && infop)
1257 retval = put_user(exit_code, &infop->si_status);
1258 if (!retval && infop)
1259 retval = put_user(pid, &infop->si_pid);
1260 if (!retval && infop)
1261 retval = put_user(uid, &infop->si_uid);
1262 if (!retval)
1263 retval = pid;
1264 put_task_struct(p);
1265
1266 BUG_ON(!retval);
1267 return retval;
1268}
1269
1270/*
1271 * Handle do_wait work for one task in a live, non-stopped state.
1272 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1273 * the lock and this task is uninteresting. If we return nonzero, we have
1274 * released the lock and the system call should return.
1275 */
1276static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1277{
1278 int retval;
1279 pid_t pid;
1280 uid_t uid;
1281
1282 if (!unlikely(wo->wo_flags & WCONTINUED))
1283 return 0;
1284
1285 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1286 return 0;
1287
1288 spin_lock_irq(&p->sighand->siglock);
1289 /* Re-check with the lock held. */
1290 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1291 spin_unlock_irq(&p->sighand->siglock);
1292 return 0;
1293 }
1294 if (!unlikely(wo->wo_flags & WNOWAIT))
1295 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1296 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1297 spin_unlock_irq(&p->sighand->siglock);
1298
1299 pid = task_pid_vnr(p);
1300 get_task_struct(p);
1301 read_unlock(&tasklist_lock);
1302
1303 if (!wo->wo_info) {
1304 retval = wo->wo_rusage
1305 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1306 put_task_struct(p);
1307 if (!retval && wo->wo_stat)
1308 retval = put_user(0xffff, wo->wo_stat);
1309 if (!retval)
1310 retval = pid;
1311 } else {
1312 retval = wait_noreap_copyout(wo, p, pid, uid,
1313 CLD_CONTINUED, SIGCONT);
1314 BUG_ON(retval == 0);
1315 }
1316
1317 return retval;
1318}
1319
1320/*
1321 * Consider @p for a wait by @parent.
1322 *
1323 * -ECHILD should be in ->notask_error before the first call.
1324 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1325 * Returns zero if the search for a child should continue;
1326 * then ->notask_error is 0 if @p is an eligible child,
1327 * or another error from security_task_wait(), or still -ECHILD.
1328 */
1329static int wait_consider_task(struct wait_opts *wo, int ptrace,
1330 struct task_struct *p)
1331{
1332 int ret;
1333
1334 if (unlikely(p->exit_state == EXIT_DEAD))
1335 return 0;
1336
1337 ret = eligible_child(wo, p);
1338 if (!ret)
1339 return ret;
1340
1341 ret = security_task_wait(p);
1342 if (unlikely(ret < 0)) {
1343 /*
1344 * If we have not yet seen any eligible child,
1345 * then let this error code replace -ECHILD.
1346 * A permission error will give the user a clue
1347 * to look for security policy problems, rather
1348 * than for mysterious wait bugs.
1349 */
1350 if (wo->notask_error)
1351 wo->notask_error = ret;
1352 return 0;
1353 }
1354
1355 if (unlikely(p->exit_state == EXIT_TRACE)) {
1356 /*
1357 * ptrace == 0 means we are the natural parent. In this case
1358 * we should clear notask_error, debugger will notify us.
1359 */
1360 if (likely(!ptrace))
1361 wo->notask_error = 0;
1362 return 0;
1363 }
1364
1365 if (likely(!ptrace) && unlikely(p->ptrace)) {
1366 /*
1367 * If it is traced by its real parent's group, just pretend
1368 * the caller is ptrace_do_wait() and reap this child if it
1369 * is zombie.
1370 *
1371 * This also hides group stop state from real parent; otherwise
1372 * a single stop can be reported twice as group and ptrace stop.
1373 * If a ptracer wants to distinguish these two events for its
1374 * own children it should create a separate process which takes
1375 * the role of real parent.
1376 */
1377 if (!ptrace_reparented(p))
1378 ptrace = 1;
1379 }
1380
1381 /* slay zombie? */
1382 if (p->exit_state == EXIT_ZOMBIE) {
1383 /* we don't reap group leaders with subthreads */
1384 if (!delay_group_leader(p)) {
1385 /*
1386 * A zombie ptracee is only visible to its ptracer.
1387 * Notification and reaping will be cascaded to the
1388 * real parent when the ptracer detaches.
1389 */
1390 if (unlikely(ptrace) || likely(!p->ptrace))
1391 return wait_task_zombie(wo, p);
1392 }
1393
1394 /*
1395 * Allow access to stopped/continued state via zombie by
1396 * falling through. Clearing of notask_error is complex.
1397 *
1398 * When !@ptrace:
1399 *
1400 * If WEXITED is set, notask_error should naturally be
1401 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1402 * so, if there are live subthreads, there are events to
1403 * wait for. If all subthreads are dead, it's still safe
1404 * to clear - this function will be called again in finite
1405 * amount time once all the subthreads are released and
1406 * will then return without clearing.
1407 *
1408 * When @ptrace:
1409 *
1410 * Stopped state is per-task and thus can't change once the
1411 * target task dies. Only continued and exited can happen.
1412 * Clear notask_error if WCONTINUED | WEXITED.
1413 */
1414 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1415 wo->notask_error = 0;
1416 } else {
1417 /*
1418 * @p is alive and it's gonna stop, continue or exit, so
1419 * there always is something to wait for.
1420 */
1421 wo->notask_error = 0;
1422 }
1423
1424 /*
1425 * Wait for stopped. Depending on @ptrace, different stopped state
1426 * is used and the two don't interact with each other.
1427 */
1428 ret = wait_task_stopped(wo, ptrace, p);
1429 if (ret)
1430 return ret;
1431
1432 /*
1433 * Wait for continued. There's only one continued state and the
1434 * ptracer can consume it which can confuse the real parent. Don't
1435 * use WCONTINUED from ptracer. You don't need or want it.
1436 */
1437 return wait_task_continued(wo, p);
1438}
1439
1440/*
1441 * Do the work of do_wait() for one thread in the group, @tsk.
1442 *
1443 * -ECHILD should be in ->notask_error before the first call.
1444 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1445 * Returns zero if the search for a child should continue; then
1446 * ->notask_error is 0 if there were any eligible children,
1447 * or another error from security_task_wait(), or still -ECHILD.
1448 */
1449static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1450{
1451 struct task_struct *p;
1452
1453 list_for_each_entry(p, &tsk->children, sibling) {
1454 int ret = wait_consider_task(wo, 0, p);
1455 if (ret)
1456 return ret;
1457 }
1458
1459 return 0;
1460}
1461
1462static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1463{
1464 struct task_struct *p;
1465
1466 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1467 int ret = wait_consider_task(wo, 1, p);
1468 if (ret)
1469 return ret;
1470 }
1471
1472 return 0;
1473}
1474
1475static int child_wait_callback(wait_queue_t *wait, unsigned mode,
1476 int sync, void *key)
1477{
1478 struct wait_opts *wo = container_of(wait, struct wait_opts,
1479 child_wait);
1480 struct task_struct *p = key;
1481
1482 if (!eligible_pid(wo, p))
1483 return 0;
1484
1485 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1486 return 0;
1487
1488 return default_wake_function(wait, mode, sync, key);
1489}
1490
1491void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1492{
1493 __wake_up_sync_key(&parent->signal->wait_chldexit,
1494 TASK_INTERRUPTIBLE, 1, p);
1495}
1496
1497static long do_wait(struct wait_opts *wo)
1498{
1499 struct task_struct *tsk;
1500 int retval;
1501
1502 trace_sched_process_wait(wo->wo_pid);
1503
1504 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1505 wo->child_wait.private = current;
1506 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1507repeat:
1508 /*
1509 * If there is nothing that can match our critiera just get out.
1510 * We will clear ->notask_error to zero if we see any child that
1511 * might later match our criteria, even if we are not able to reap
1512 * it yet.
1513 */
1514 wo->notask_error = -ECHILD;
1515 if ((wo->wo_type < PIDTYPE_MAX) &&
1516 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1517 goto notask;
1518
1519 set_current_state(TASK_INTERRUPTIBLE);
1520 read_lock(&tasklist_lock);
1521 tsk = current;
1522 do {
1523 retval = do_wait_thread(wo, tsk);
1524 if (retval)
1525 goto end;
1526
1527 retval = ptrace_do_wait(wo, tsk);
1528 if (retval)
1529 goto end;
1530
1531 if (wo->wo_flags & __WNOTHREAD)
1532 break;
1533 } while_each_thread(current, tsk);
1534 read_unlock(&tasklist_lock);
1535
1536notask:
1537 retval = wo->notask_error;
1538 if (!retval && !(wo->wo_flags & WNOHANG)) {
1539 retval = -ERESTARTSYS;
1540 if (!signal_pending(current)) {
1541 schedule();
1542 goto repeat;
1543 }
1544 }
1545end:
1546 __set_current_state(TASK_RUNNING);
1547 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1548 return retval;
1549}
1550
1551SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1552 infop, int, options, struct rusage __user *, ru)
1553{
1554 struct wait_opts wo;
1555 struct pid *pid = NULL;
1556 enum pid_type type;
1557 long ret;
1558
1559 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1560 return -EINVAL;
1561 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1562 return -EINVAL;
1563
1564 switch (which) {
1565 case P_ALL:
1566 type = PIDTYPE_MAX;
1567 break;
1568 case P_PID:
1569 type = PIDTYPE_PID;
1570 if (upid <= 0)
1571 return -EINVAL;
1572 break;
1573 case P_PGID:
1574 type = PIDTYPE_PGID;
1575 if (upid <= 0)
1576 return -EINVAL;
1577 break;
1578 default:
1579 return -EINVAL;
1580 }
1581
1582 if (type < PIDTYPE_MAX)
1583 pid = find_get_pid(upid);
1584
1585 wo.wo_type = type;
1586 wo.wo_pid = pid;
1587 wo.wo_flags = options;
1588 wo.wo_info = infop;
1589 wo.wo_stat = NULL;
1590 wo.wo_rusage = ru;
1591 ret = do_wait(&wo);
1592
1593 if (ret > 0) {
1594 ret = 0;
1595 } else if (infop) {
1596 /*
1597 * For a WNOHANG return, clear out all the fields
1598 * we would set so the user can easily tell the
1599 * difference.
1600 */
1601 if (!ret)
1602 ret = put_user(0, &infop->si_signo);
1603 if (!ret)
1604 ret = put_user(0, &infop->si_errno);
1605 if (!ret)
1606 ret = put_user(0, &infop->si_code);
1607 if (!ret)
1608 ret = put_user(0, &infop->si_pid);
1609 if (!ret)
1610 ret = put_user(0, &infop->si_uid);
1611 if (!ret)
1612 ret = put_user(0, &infop->si_status);
1613 }
1614
1615 put_pid(pid);
1616 return ret;
1617}
1618
1619SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1620 int, options, struct rusage __user *, ru)
1621{
1622 struct wait_opts wo;
1623 struct pid *pid = NULL;
1624 enum pid_type type;
1625 long ret;
1626
1627 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1628 __WNOTHREAD|__WCLONE|__WALL))
1629 return -EINVAL;
1630
1631 if (upid == -1)
1632 type = PIDTYPE_MAX;
1633 else if (upid < 0) {
1634 type = PIDTYPE_PGID;
1635 pid = find_get_pid(-upid);
1636 } else if (upid == 0) {
1637 type = PIDTYPE_PGID;
1638 pid = get_task_pid(current, PIDTYPE_PGID);
1639 } else /* upid > 0 */ {
1640 type = PIDTYPE_PID;
1641 pid = find_get_pid(upid);
1642 }
1643
1644 wo.wo_type = type;
1645 wo.wo_pid = pid;
1646 wo.wo_flags = options | WEXITED;
1647 wo.wo_info = NULL;
1648 wo.wo_stat = stat_addr;
1649 wo.wo_rusage = ru;
1650 ret = do_wait(&wo);
1651 put_pid(pid);
1652
1653 return ret;
1654}
1655
1656#ifdef __ARCH_WANT_SYS_WAITPID
1657
1658/*
1659 * sys_waitpid() remains for compatibility. waitpid() should be
1660 * implemented by calling sys_wait4() from libc.a.
1661 */
1662SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1663{
1664 return sys_wait4(pid, stat_addr, options, NULL);
1665}
1666
1667#endif
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/freezer.h>
29#include <linux/binfmts.h>
30#include <linux/nsproxy.h>
31#include <linux/pid_namespace.h>
32#include <linux/ptrace.h>
33#include <linux/profile.h>
34#include <linux/mount.h>
35#include <linux/proc_fs.h>
36#include <linux/kthread.h>
37#include <linux/mempolicy.h>
38#include <linux/taskstats_kern.h>
39#include <linux/delayacct.h>
40#include <linux/cgroup.h>
41#include <linux/syscalls.h>
42#include <linux/signal.h>
43#include <linux/posix-timers.h>
44#include <linux/cn_proc.h>
45#include <linux/mutex.h>
46#include <linux/futex.h>
47#include <linux/pipe_fs_i.h>
48#include <linux/audit.h> /* for audit_free() */
49#include <linux/resource.h>
50#include <linux/task_io_accounting_ops.h>
51#include <linux/blkdev.h>
52#include <linux/task_work.h>
53#include <linux/fs_struct.h>
54#include <linux/init_task.h>
55#include <linux/perf_event.h>
56#include <trace/events/sched.h>
57#include <linux/hw_breakpoint.h>
58#include <linux/oom.h>
59#include <linux/writeback.h>
60#include <linux/shm.h>
61#include <linux/kcov.h>
62#include <linux/kmsan.h>
63#include <linux/random.h>
64#include <linux/rcuwait.h>
65#include <linux/compat.h>
66#include <linux/io_uring.h>
67#include <linux/kprobes.h>
68#include <linux/rethook.h>
69#include <linux/sysfs.h>
70#include <linux/user_events.h>
71#include <linux/uaccess.h>
72
73#include <uapi/linux/wait.h>
74
75#include <asm/unistd.h>
76#include <asm/mmu_context.h>
77
78#include "exit.h"
79
80/*
81 * The default value should be high enough to not crash a system that randomly
82 * crashes its kernel from time to time, but low enough to at least not permit
83 * overflowing 32-bit refcounts or the ldsem writer count.
84 */
85static unsigned int oops_limit = 10000;
86
87#ifdef CONFIG_SYSCTL
88static struct ctl_table kern_exit_table[] = {
89 {
90 .procname = "oops_limit",
91 .data = &oops_limit,
92 .maxlen = sizeof(oops_limit),
93 .mode = 0644,
94 .proc_handler = proc_douintvec,
95 },
96};
97
98static __init int kernel_exit_sysctls_init(void)
99{
100 register_sysctl_init("kernel", kern_exit_table);
101 return 0;
102}
103late_initcall(kernel_exit_sysctls_init);
104#endif
105
106static atomic_t oops_count = ATOMIC_INIT(0);
107
108#ifdef CONFIG_SYSFS
109static ssize_t oops_count_show(struct kobject *kobj, struct kobj_attribute *attr,
110 char *page)
111{
112 return sysfs_emit(page, "%d\n", atomic_read(&oops_count));
113}
114
115static struct kobj_attribute oops_count_attr = __ATTR_RO(oops_count);
116
117static __init int kernel_exit_sysfs_init(void)
118{
119 sysfs_add_file_to_group(kernel_kobj, &oops_count_attr.attr, NULL);
120 return 0;
121}
122late_initcall(kernel_exit_sysfs_init);
123#endif
124
125static void __unhash_process(struct task_struct *p, bool group_dead)
126{
127 nr_threads--;
128 detach_pid(p, PIDTYPE_PID);
129 if (group_dead) {
130 detach_pid(p, PIDTYPE_TGID);
131 detach_pid(p, PIDTYPE_PGID);
132 detach_pid(p, PIDTYPE_SID);
133
134 list_del_rcu(&p->tasks);
135 list_del_init(&p->sibling);
136 __this_cpu_dec(process_counts);
137 }
138 list_del_rcu(&p->thread_node);
139}
140
141/*
142 * This function expects the tasklist_lock write-locked.
143 */
144static void __exit_signal(struct task_struct *tsk)
145{
146 struct signal_struct *sig = tsk->signal;
147 bool group_dead = thread_group_leader(tsk);
148 struct sighand_struct *sighand;
149 struct tty_struct *tty;
150 u64 utime, stime;
151
152 sighand = rcu_dereference_check(tsk->sighand,
153 lockdep_tasklist_lock_is_held());
154 spin_lock(&sighand->siglock);
155
156#ifdef CONFIG_POSIX_TIMERS
157 posix_cpu_timers_exit(tsk);
158 if (group_dead)
159 posix_cpu_timers_exit_group(tsk);
160#endif
161
162 if (group_dead) {
163 tty = sig->tty;
164 sig->tty = NULL;
165 } else {
166 /*
167 * If there is any task waiting for the group exit
168 * then notify it:
169 */
170 if (sig->notify_count > 0 && !--sig->notify_count)
171 wake_up_process(sig->group_exec_task);
172
173 if (tsk == sig->curr_target)
174 sig->curr_target = next_thread(tsk);
175 }
176
177 add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
178 sizeof(unsigned long long));
179
180 /*
181 * Accumulate here the counters for all threads as they die. We could
182 * skip the group leader because it is the last user of signal_struct,
183 * but we want to avoid the race with thread_group_cputime() which can
184 * see the empty ->thread_head list.
185 */
186 task_cputime(tsk, &utime, &stime);
187 write_seqlock(&sig->stats_lock);
188 sig->utime += utime;
189 sig->stime += stime;
190 sig->gtime += task_gtime(tsk);
191 sig->min_flt += tsk->min_flt;
192 sig->maj_flt += tsk->maj_flt;
193 sig->nvcsw += tsk->nvcsw;
194 sig->nivcsw += tsk->nivcsw;
195 sig->inblock += task_io_get_inblock(tsk);
196 sig->oublock += task_io_get_oublock(tsk);
197 task_io_accounting_add(&sig->ioac, &tsk->ioac);
198 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
199 sig->nr_threads--;
200 __unhash_process(tsk, group_dead);
201 write_sequnlock(&sig->stats_lock);
202
203 /*
204 * Do this under ->siglock, we can race with another thread
205 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
206 */
207 flush_sigqueue(&tsk->pending);
208 tsk->sighand = NULL;
209 spin_unlock(&sighand->siglock);
210
211 __cleanup_sighand(sighand);
212 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
213 if (group_dead) {
214 flush_sigqueue(&sig->shared_pending);
215 tty_kref_put(tty);
216 }
217}
218
219static void delayed_put_task_struct(struct rcu_head *rhp)
220{
221 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
222
223 kprobe_flush_task(tsk);
224 rethook_flush_task(tsk);
225 perf_event_delayed_put(tsk);
226 trace_sched_process_free(tsk);
227 put_task_struct(tsk);
228}
229
230void put_task_struct_rcu_user(struct task_struct *task)
231{
232 if (refcount_dec_and_test(&task->rcu_users))
233 call_rcu(&task->rcu, delayed_put_task_struct);
234}
235
236void __weak release_thread(struct task_struct *dead_task)
237{
238}
239
240void release_task(struct task_struct *p)
241{
242 struct task_struct *leader;
243 struct pid *thread_pid;
244 int zap_leader;
245repeat:
246 /* don't need to get the RCU readlock here - the process is dead and
247 * can't be modifying its own credentials. But shut RCU-lockdep up */
248 rcu_read_lock();
249 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
250 rcu_read_unlock();
251
252 cgroup_release(p);
253
254 write_lock_irq(&tasklist_lock);
255 ptrace_release_task(p);
256 thread_pid = get_pid(p->thread_pid);
257 __exit_signal(p);
258
259 /*
260 * If we are the last non-leader member of the thread
261 * group, and the leader is zombie, then notify the
262 * group leader's parent process. (if it wants notification.)
263 */
264 zap_leader = 0;
265 leader = p->group_leader;
266 if (leader != p && thread_group_empty(leader)
267 && leader->exit_state == EXIT_ZOMBIE) {
268 /*
269 * If we were the last child thread and the leader has
270 * exited already, and the leader's parent ignores SIGCHLD,
271 * then we are the one who should release the leader.
272 */
273 zap_leader = do_notify_parent(leader, leader->exit_signal);
274 if (zap_leader)
275 leader->exit_state = EXIT_DEAD;
276 }
277
278 write_unlock_irq(&tasklist_lock);
279 proc_flush_pid(thread_pid);
280 put_pid(thread_pid);
281 release_thread(p);
282 put_task_struct_rcu_user(p);
283
284 p = leader;
285 if (unlikely(zap_leader))
286 goto repeat;
287}
288
289int rcuwait_wake_up(struct rcuwait *w)
290{
291 int ret = 0;
292 struct task_struct *task;
293
294 rcu_read_lock();
295
296 /*
297 * Order condition vs @task, such that everything prior to the load
298 * of @task is visible. This is the condition as to why the user called
299 * rcuwait_wake() in the first place. Pairs with set_current_state()
300 * barrier (A) in rcuwait_wait_event().
301 *
302 * WAIT WAKE
303 * [S] tsk = current [S] cond = true
304 * MB (A) MB (B)
305 * [L] cond [L] tsk
306 */
307 smp_mb(); /* (B) */
308
309 task = rcu_dereference(w->task);
310 if (task)
311 ret = wake_up_process(task);
312 rcu_read_unlock();
313
314 return ret;
315}
316EXPORT_SYMBOL_GPL(rcuwait_wake_up);
317
318/*
319 * Determine if a process group is "orphaned", according to the POSIX
320 * definition in 2.2.2.52. Orphaned process groups are not to be affected
321 * by terminal-generated stop signals. Newly orphaned process groups are
322 * to receive a SIGHUP and a SIGCONT.
323 *
324 * "I ask you, have you ever known what it is to be an orphan?"
325 */
326static int will_become_orphaned_pgrp(struct pid *pgrp,
327 struct task_struct *ignored_task)
328{
329 struct task_struct *p;
330
331 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
332 if ((p == ignored_task) ||
333 (p->exit_state && thread_group_empty(p)) ||
334 is_global_init(p->real_parent))
335 continue;
336
337 if (task_pgrp(p->real_parent) != pgrp &&
338 task_session(p->real_parent) == task_session(p))
339 return 0;
340 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
341
342 return 1;
343}
344
345int is_current_pgrp_orphaned(void)
346{
347 int retval;
348
349 read_lock(&tasklist_lock);
350 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
351 read_unlock(&tasklist_lock);
352
353 return retval;
354}
355
356static bool has_stopped_jobs(struct pid *pgrp)
357{
358 struct task_struct *p;
359
360 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
361 if (p->signal->flags & SIGNAL_STOP_STOPPED)
362 return true;
363 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
364
365 return false;
366}
367
368/*
369 * Check to see if any process groups have become orphaned as
370 * a result of our exiting, and if they have any stopped jobs,
371 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
372 */
373static void
374kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
375{
376 struct pid *pgrp = task_pgrp(tsk);
377 struct task_struct *ignored_task = tsk;
378
379 if (!parent)
380 /* exit: our father is in a different pgrp than
381 * we are and we were the only connection outside.
382 */
383 parent = tsk->real_parent;
384 else
385 /* reparent: our child is in a different pgrp than
386 * we are, and it was the only connection outside.
387 */
388 ignored_task = NULL;
389
390 if (task_pgrp(parent) != pgrp &&
391 task_session(parent) == task_session(tsk) &&
392 will_become_orphaned_pgrp(pgrp, ignored_task) &&
393 has_stopped_jobs(pgrp)) {
394 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
395 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
396 }
397}
398
399static void coredump_task_exit(struct task_struct *tsk)
400{
401 struct core_state *core_state;
402
403 /*
404 * Serialize with any possible pending coredump.
405 * We must hold siglock around checking core_state
406 * and setting PF_POSTCOREDUMP. The core-inducing thread
407 * will increment ->nr_threads for each thread in the
408 * group without PF_POSTCOREDUMP set.
409 */
410 spin_lock_irq(&tsk->sighand->siglock);
411 tsk->flags |= PF_POSTCOREDUMP;
412 core_state = tsk->signal->core_state;
413 spin_unlock_irq(&tsk->sighand->siglock);
414 if (core_state) {
415 struct core_thread self;
416
417 self.task = current;
418 if (self.task->flags & PF_SIGNALED)
419 self.next = xchg(&core_state->dumper.next, &self);
420 else
421 self.task = NULL;
422 /*
423 * Implies mb(), the result of xchg() must be visible
424 * to core_state->dumper.
425 */
426 if (atomic_dec_and_test(&core_state->nr_threads))
427 complete(&core_state->startup);
428
429 for (;;) {
430 set_current_state(TASK_IDLE|TASK_FREEZABLE);
431 if (!self.task) /* see coredump_finish() */
432 break;
433 schedule();
434 }
435 __set_current_state(TASK_RUNNING);
436 }
437}
438
439#ifdef CONFIG_MEMCG
440/* drops tasklist_lock if succeeds */
441static bool __try_to_set_owner(struct task_struct *tsk, struct mm_struct *mm)
442{
443 bool ret = false;
444
445 task_lock(tsk);
446 if (likely(tsk->mm == mm)) {
447 /* tsk can't pass exit_mm/exec_mmap and exit */
448 read_unlock(&tasklist_lock);
449 WRITE_ONCE(mm->owner, tsk);
450 lru_gen_migrate_mm(mm);
451 ret = true;
452 }
453 task_unlock(tsk);
454 return ret;
455}
456
457static bool try_to_set_owner(struct task_struct *g, struct mm_struct *mm)
458{
459 struct task_struct *t;
460
461 for_each_thread(g, t) {
462 struct mm_struct *t_mm = READ_ONCE(t->mm);
463 if (t_mm == mm) {
464 if (__try_to_set_owner(t, mm))
465 return true;
466 } else if (t_mm)
467 break;
468 }
469
470 return false;
471}
472
473/*
474 * A task is exiting. If it owned this mm, find a new owner for the mm.
475 */
476void mm_update_next_owner(struct mm_struct *mm)
477{
478 struct task_struct *g, *p = current;
479
480 /*
481 * If the exiting or execing task is not the owner, it's
482 * someone else's problem.
483 */
484 if (mm->owner != p)
485 return;
486 /*
487 * The current owner is exiting/execing and there are no other
488 * candidates. Do not leave the mm pointing to a possibly
489 * freed task structure.
490 */
491 if (atomic_read(&mm->mm_users) <= 1) {
492 WRITE_ONCE(mm->owner, NULL);
493 return;
494 }
495
496 read_lock(&tasklist_lock);
497 /*
498 * Search in the children
499 */
500 list_for_each_entry(g, &p->children, sibling) {
501 if (try_to_set_owner(g, mm))
502 goto ret;
503 }
504 /*
505 * Search in the siblings
506 */
507 list_for_each_entry(g, &p->real_parent->children, sibling) {
508 if (try_to_set_owner(g, mm))
509 goto ret;
510 }
511 /*
512 * Search through everything else, we should not get here often.
513 */
514 for_each_process(g) {
515 if (atomic_read(&mm->mm_users) <= 1)
516 break;
517 if (g->flags & PF_KTHREAD)
518 continue;
519 if (try_to_set_owner(g, mm))
520 goto ret;
521 }
522 read_unlock(&tasklist_lock);
523 /*
524 * We found no owner yet mm_users > 1: this implies that we are
525 * most likely racing with swapoff (try_to_unuse()) or /proc or
526 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
527 */
528 WRITE_ONCE(mm->owner, NULL);
529 ret:
530 return;
531
532}
533#endif /* CONFIG_MEMCG */
534
535/*
536 * Turn us into a lazy TLB process if we
537 * aren't already..
538 */
539static void exit_mm(void)
540{
541 struct mm_struct *mm = current->mm;
542
543 exit_mm_release(current, mm);
544 if (!mm)
545 return;
546 mmap_read_lock(mm);
547 mmgrab_lazy_tlb(mm);
548 BUG_ON(mm != current->active_mm);
549 /* more a memory barrier than a real lock */
550 task_lock(current);
551 /*
552 * When a thread stops operating on an address space, the loop
553 * in membarrier_private_expedited() may not observe that
554 * tsk->mm, and the loop in membarrier_global_expedited() may
555 * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED
556 * rq->membarrier_state, so those would not issue an IPI.
557 * Membarrier requires a memory barrier after accessing
558 * user-space memory, before clearing tsk->mm or the
559 * rq->membarrier_state.
560 */
561 smp_mb__after_spinlock();
562 local_irq_disable();
563 current->mm = NULL;
564 membarrier_update_current_mm(NULL);
565 enter_lazy_tlb(mm, current);
566 local_irq_enable();
567 task_unlock(current);
568 mmap_read_unlock(mm);
569 mm_update_next_owner(mm);
570 mmput(mm);
571 if (test_thread_flag(TIF_MEMDIE))
572 exit_oom_victim();
573}
574
575static struct task_struct *find_alive_thread(struct task_struct *p)
576{
577 struct task_struct *t;
578
579 for_each_thread(p, t) {
580 if (!(t->flags & PF_EXITING))
581 return t;
582 }
583 return NULL;
584}
585
586static struct task_struct *find_child_reaper(struct task_struct *father,
587 struct list_head *dead)
588 __releases(&tasklist_lock)
589 __acquires(&tasklist_lock)
590{
591 struct pid_namespace *pid_ns = task_active_pid_ns(father);
592 struct task_struct *reaper = pid_ns->child_reaper;
593 struct task_struct *p, *n;
594
595 if (likely(reaper != father))
596 return reaper;
597
598 reaper = find_alive_thread(father);
599 if (reaper) {
600 pid_ns->child_reaper = reaper;
601 return reaper;
602 }
603
604 write_unlock_irq(&tasklist_lock);
605
606 list_for_each_entry_safe(p, n, dead, ptrace_entry) {
607 list_del_init(&p->ptrace_entry);
608 release_task(p);
609 }
610
611 zap_pid_ns_processes(pid_ns);
612 write_lock_irq(&tasklist_lock);
613
614 return father;
615}
616
617/*
618 * When we die, we re-parent all our children, and try to:
619 * 1. give them to another thread in our thread group, if such a member exists
620 * 2. give it to the first ancestor process which prctl'd itself as a
621 * child_subreaper for its children (like a service manager)
622 * 3. give it to the init process (PID 1) in our pid namespace
623 */
624static struct task_struct *find_new_reaper(struct task_struct *father,
625 struct task_struct *child_reaper)
626{
627 struct task_struct *thread, *reaper;
628
629 thread = find_alive_thread(father);
630 if (thread)
631 return thread;
632
633 if (father->signal->has_child_subreaper) {
634 unsigned int ns_level = task_pid(father)->level;
635 /*
636 * Find the first ->is_child_subreaper ancestor in our pid_ns.
637 * We can't check reaper != child_reaper to ensure we do not
638 * cross the namespaces, the exiting parent could be injected
639 * by setns() + fork().
640 * We check pid->level, this is slightly more efficient than
641 * task_active_pid_ns(reaper) != task_active_pid_ns(father).
642 */
643 for (reaper = father->real_parent;
644 task_pid(reaper)->level == ns_level;
645 reaper = reaper->real_parent) {
646 if (reaper == &init_task)
647 break;
648 if (!reaper->signal->is_child_subreaper)
649 continue;
650 thread = find_alive_thread(reaper);
651 if (thread)
652 return thread;
653 }
654 }
655
656 return child_reaper;
657}
658
659/*
660* Any that need to be release_task'd are put on the @dead list.
661 */
662static void reparent_leader(struct task_struct *father, struct task_struct *p,
663 struct list_head *dead)
664{
665 if (unlikely(p->exit_state == EXIT_DEAD))
666 return;
667
668 /* We don't want people slaying init. */
669 p->exit_signal = SIGCHLD;
670
671 /* If it has exited notify the new parent about this child's death. */
672 if (!p->ptrace &&
673 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
674 if (do_notify_parent(p, p->exit_signal)) {
675 p->exit_state = EXIT_DEAD;
676 list_add(&p->ptrace_entry, dead);
677 }
678 }
679
680 kill_orphaned_pgrp(p, father);
681}
682
683/*
684 * This does two things:
685 *
686 * A. Make init inherit all the child processes
687 * B. Check to see if any process groups have become orphaned
688 * as a result of our exiting, and if they have any stopped
689 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
690 */
691static void forget_original_parent(struct task_struct *father,
692 struct list_head *dead)
693{
694 struct task_struct *p, *t, *reaper;
695
696 if (unlikely(!list_empty(&father->ptraced)))
697 exit_ptrace(father, dead);
698
699 /* Can drop and reacquire tasklist_lock */
700 reaper = find_child_reaper(father, dead);
701 if (list_empty(&father->children))
702 return;
703
704 reaper = find_new_reaper(father, reaper);
705 list_for_each_entry(p, &father->children, sibling) {
706 for_each_thread(p, t) {
707 RCU_INIT_POINTER(t->real_parent, reaper);
708 BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father));
709 if (likely(!t->ptrace))
710 t->parent = t->real_parent;
711 if (t->pdeath_signal)
712 group_send_sig_info(t->pdeath_signal,
713 SEND_SIG_NOINFO, t,
714 PIDTYPE_TGID);
715 }
716 /*
717 * If this is a threaded reparent there is no need to
718 * notify anyone anything has happened.
719 */
720 if (!same_thread_group(reaper, father))
721 reparent_leader(father, p, dead);
722 }
723 list_splice_tail_init(&father->children, &reaper->children);
724}
725
726/*
727 * Send signals to all our closest relatives so that they know
728 * to properly mourn us..
729 */
730static void exit_notify(struct task_struct *tsk, int group_dead)
731{
732 bool autoreap;
733 struct task_struct *p, *n;
734 LIST_HEAD(dead);
735
736 write_lock_irq(&tasklist_lock);
737 forget_original_parent(tsk, &dead);
738
739 if (group_dead)
740 kill_orphaned_pgrp(tsk->group_leader, NULL);
741
742 tsk->exit_state = EXIT_ZOMBIE;
743 /*
744 * sub-thread or delay_group_leader(), wake up the
745 * PIDFD_THREAD waiters.
746 */
747 if (!thread_group_empty(tsk))
748 do_notify_pidfd(tsk);
749
750 if (unlikely(tsk->ptrace)) {
751 int sig = thread_group_leader(tsk) &&
752 thread_group_empty(tsk) &&
753 !ptrace_reparented(tsk) ?
754 tsk->exit_signal : SIGCHLD;
755 autoreap = do_notify_parent(tsk, sig);
756 } else if (thread_group_leader(tsk)) {
757 autoreap = thread_group_empty(tsk) &&
758 do_notify_parent(tsk, tsk->exit_signal);
759 } else {
760 autoreap = true;
761 }
762
763 if (autoreap) {
764 tsk->exit_state = EXIT_DEAD;
765 list_add(&tsk->ptrace_entry, &dead);
766 }
767
768 /* mt-exec, de_thread() is waiting for group leader */
769 if (unlikely(tsk->signal->notify_count < 0))
770 wake_up_process(tsk->signal->group_exec_task);
771 write_unlock_irq(&tasklist_lock);
772
773 list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
774 list_del_init(&p->ptrace_entry);
775 release_task(p);
776 }
777}
778
779#ifdef CONFIG_DEBUG_STACK_USAGE
780unsigned long stack_not_used(struct task_struct *p)
781{
782 unsigned long *n = end_of_stack(p);
783
784 do { /* Skip over canary */
785# ifdef CONFIG_STACK_GROWSUP
786 n--;
787# else
788 n++;
789# endif
790 } while (!*n);
791
792# ifdef CONFIG_STACK_GROWSUP
793 return (unsigned long)end_of_stack(p) - (unsigned long)n;
794# else
795 return (unsigned long)n - (unsigned long)end_of_stack(p);
796# endif
797}
798
799/* Count the maximum pages reached in kernel stacks */
800static inline void kstack_histogram(unsigned long used_stack)
801{
802#ifdef CONFIG_VM_EVENT_COUNTERS
803 if (used_stack <= 1024)
804 count_vm_event(KSTACK_1K);
805#if THREAD_SIZE > 1024
806 else if (used_stack <= 2048)
807 count_vm_event(KSTACK_2K);
808#endif
809#if THREAD_SIZE > 2048
810 else if (used_stack <= 4096)
811 count_vm_event(KSTACK_4K);
812#endif
813#if THREAD_SIZE > 4096
814 else if (used_stack <= 8192)
815 count_vm_event(KSTACK_8K);
816#endif
817#if THREAD_SIZE > 8192
818 else if (used_stack <= 16384)
819 count_vm_event(KSTACK_16K);
820#endif
821#if THREAD_SIZE > 16384
822 else if (used_stack <= 32768)
823 count_vm_event(KSTACK_32K);
824#endif
825#if THREAD_SIZE > 32768
826 else if (used_stack <= 65536)
827 count_vm_event(KSTACK_64K);
828#endif
829#if THREAD_SIZE > 65536
830 else
831 count_vm_event(KSTACK_REST);
832#endif
833#endif /* CONFIG_VM_EVENT_COUNTERS */
834}
835
836static void check_stack_usage(void)
837{
838 static DEFINE_SPINLOCK(low_water_lock);
839 static int lowest_to_date = THREAD_SIZE;
840 unsigned long free;
841
842 free = stack_not_used(current);
843 kstack_histogram(THREAD_SIZE - free);
844
845 if (free >= lowest_to_date)
846 return;
847
848 spin_lock(&low_water_lock);
849 if (free < lowest_to_date) {
850 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
851 current->comm, task_pid_nr(current), free);
852 lowest_to_date = free;
853 }
854 spin_unlock(&low_water_lock);
855}
856#else
857static inline void check_stack_usage(void) {}
858#endif
859
860static void synchronize_group_exit(struct task_struct *tsk, long code)
861{
862 struct sighand_struct *sighand = tsk->sighand;
863 struct signal_struct *signal = tsk->signal;
864
865 spin_lock_irq(&sighand->siglock);
866 signal->quick_threads--;
867 if ((signal->quick_threads == 0) &&
868 !(signal->flags & SIGNAL_GROUP_EXIT)) {
869 signal->flags = SIGNAL_GROUP_EXIT;
870 signal->group_exit_code = code;
871 signal->group_stop_count = 0;
872 }
873 spin_unlock_irq(&sighand->siglock);
874}
875
876void __noreturn do_exit(long code)
877{
878 struct task_struct *tsk = current;
879 int group_dead;
880
881 WARN_ON(irqs_disabled());
882
883 synchronize_group_exit(tsk, code);
884
885 WARN_ON(tsk->plug);
886
887 kcov_task_exit(tsk);
888 kmsan_task_exit(tsk);
889
890 coredump_task_exit(tsk);
891 ptrace_event(PTRACE_EVENT_EXIT, code);
892 user_events_exit(tsk);
893
894 io_uring_files_cancel();
895 exit_signals(tsk); /* sets PF_EXITING */
896
897 seccomp_filter_release(tsk);
898
899 acct_update_integrals(tsk);
900 group_dead = atomic_dec_and_test(&tsk->signal->live);
901 if (group_dead) {
902 /*
903 * If the last thread of global init has exited, panic
904 * immediately to get a useable coredump.
905 */
906 if (unlikely(is_global_init(tsk)))
907 panic("Attempted to kill init! exitcode=0x%08x\n",
908 tsk->signal->group_exit_code ?: (int)code);
909
910#ifdef CONFIG_POSIX_TIMERS
911 hrtimer_cancel(&tsk->signal->real_timer);
912 exit_itimers(tsk);
913#endif
914 if (tsk->mm)
915 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
916 }
917 acct_collect(code, group_dead);
918 if (group_dead)
919 tty_audit_exit();
920 audit_free(tsk);
921
922 tsk->exit_code = code;
923 taskstats_exit(tsk, group_dead);
924
925 exit_mm();
926
927 if (group_dead)
928 acct_process();
929 trace_sched_process_exit(tsk);
930
931 exit_sem(tsk);
932 exit_shm(tsk);
933 exit_files(tsk);
934 exit_fs(tsk);
935 if (group_dead)
936 disassociate_ctty(1);
937 exit_task_namespaces(tsk);
938 exit_task_work(tsk);
939 exit_thread(tsk);
940
941 /*
942 * Flush inherited counters to the parent - before the parent
943 * gets woken up by child-exit notifications.
944 *
945 * because of cgroup mode, must be called before cgroup_exit()
946 */
947 perf_event_exit_task(tsk);
948
949 sched_autogroup_exit_task(tsk);
950 cgroup_exit(tsk);
951
952 /*
953 * FIXME: do that only when needed, using sched_exit tracepoint
954 */
955 flush_ptrace_hw_breakpoint(tsk);
956
957 exit_tasks_rcu_start();
958 exit_notify(tsk, group_dead);
959 proc_exit_connector(tsk);
960 mpol_put_task_policy(tsk);
961#ifdef CONFIG_FUTEX
962 if (unlikely(current->pi_state_cache))
963 kfree(current->pi_state_cache);
964#endif
965 /*
966 * Make sure we are holding no locks:
967 */
968 debug_check_no_locks_held();
969
970 if (tsk->io_context)
971 exit_io_context(tsk);
972
973 if (tsk->splice_pipe)
974 free_pipe_info(tsk->splice_pipe);
975
976 if (tsk->task_frag.page)
977 put_page(tsk->task_frag.page);
978
979 exit_task_stack_account(tsk);
980
981 check_stack_usage();
982 preempt_disable();
983 if (tsk->nr_dirtied)
984 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
985 exit_rcu();
986 exit_tasks_rcu_finish();
987
988 lockdep_free_task(tsk);
989 do_task_dead();
990}
991
992void __noreturn make_task_dead(int signr)
993{
994 /*
995 * Take the task off the cpu after something catastrophic has
996 * happened.
997 *
998 * We can get here from a kernel oops, sometimes with preemption off.
999 * Start by checking for critical errors.
1000 * Then fix up important state like USER_DS and preemption.
1001 * Then do everything else.
1002 */
1003 struct task_struct *tsk = current;
1004 unsigned int limit;
1005
1006 if (unlikely(in_interrupt()))
1007 panic("Aiee, killing interrupt handler!");
1008 if (unlikely(!tsk->pid))
1009 panic("Attempted to kill the idle task!");
1010
1011 if (unlikely(irqs_disabled())) {
1012 pr_info("note: %s[%d] exited with irqs disabled\n",
1013 current->comm, task_pid_nr(current));
1014 local_irq_enable();
1015 }
1016 if (unlikely(in_atomic())) {
1017 pr_info("note: %s[%d] exited with preempt_count %d\n",
1018 current->comm, task_pid_nr(current),
1019 preempt_count());
1020 preempt_count_set(PREEMPT_ENABLED);
1021 }
1022
1023 /*
1024 * Every time the system oopses, if the oops happens while a reference
1025 * to an object was held, the reference leaks.
1026 * If the oops doesn't also leak memory, repeated oopsing can cause
1027 * reference counters to wrap around (if they're not using refcount_t).
1028 * This means that repeated oopsing can make unexploitable-looking bugs
1029 * exploitable through repeated oopsing.
1030 * To make sure this can't happen, place an upper bound on how often the
1031 * kernel may oops without panic().
1032 */
1033 limit = READ_ONCE(oops_limit);
1034 if (atomic_inc_return(&oops_count) >= limit && limit)
1035 panic("Oopsed too often (kernel.oops_limit is %d)", limit);
1036
1037 /*
1038 * We're taking recursive faults here in make_task_dead. Safest is to just
1039 * leave this task alone and wait for reboot.
1040 */
1041 if (unlikely(tsk->flags & PF_EXITING)) {
1042 pr_alert("Fixing recursive fault but reboot is needed!\n");
1043 futex_exit_recursive(tsk);
1044 tsk->exit_state = EXIT_DEAD;
1045 refcount_inc(&tsk->rcu_users);
1046 do_task_dead();
1047 }
1048
1049 do_exit(signr);
1050}
1051
1052SYSCALL_DEFINE1(exit, int, error_code)
1053{
1054 do_exit((error_code&0xff)<<8);
1055}
1056
1057/*
1058 * Take down every thread in the group. This is called by fatal signals
1059 * as well as by sys_exit_group (below).
1060 */
1061void __noreturn
1062do_group_exit(int exit_code)
1063{
1064 struct signal_struct *sig = current->signal;
1065
1066 if (sig->flags & SIGNAL_GROUP_EXIT)
1067 exit_code = sig->group_exit_code;
1068 else if (sig->group_exec_task)
1069 exit_code = 0;
1070 else {
1071 struct sighand_struct *const sighand = current->sighand;
1072
1073 spin_lock_irq(&sighand->siglock);
1074 if (sig->flags & SIGNAL_GROUP_EXIT)
1075 /* Another thread got here before we took the lock. */
1076 exit_code = sig->group_exit_code;
1077 else if (sig->group_exec_task)
1078 exit_code = 0;
1079 else {
1080 sig->group_exit_code = exit_code;
1081 sig->flags = SIGNAL_GROUP_EXIT;
1082 zap_other_threads(current);
1083 }
1084 spin_unlock_irq(&sighand->siglock);
1085 }
1086
1087 do_exit(exit_code);
1088 /* NOTREACHED */
1089}
1090
1091/*
1092 * this kills every thread in the thread group. Note that any externally
1093 * wait4()-ing process will get the correct exit code - even if this
1094 * thread is not the thread group leader.
1095 */
1096SYSCALL_DEFINE1(exit_group, int, error_code)
1097{
1098 do_group_exit((error_code & 0xff) << 8);
1099 /* NOTREACHED */
1100 return 0;
1101}
1102
1103static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
1104{
1105 return wo->wo_type == PIDTYPE_MAX ||
1106 task_pid_type(p, wo->wo_type) == wo->wo_pid;
1107}
1108
1109static int
1110eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
1111{
1112 if (!eligible_pid(wo, p))
1113 return 0;
1114
1115 /*
1116 * Wait for all children (clone and not) if __WALL is set or
1117 * if it is traced by us.
1118 */
1119 if (ptrace || (wo->wo_flags & __WALL))
1120 return 1;
1121
1122 /*
1123 * Otherwise, wait for clone children *only* if __WCLONE is set;
1124 * otherwise, wait for non-clone children *only*.
1125 *
1126 * Note: a "clone" child here is one that reports to its parent
1127 * using a signal other than SIGCHLD, or a non-leader thread which
1128 * we can only see if it is traced by us.
1129 */
1130 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
1131 return 0;
1132
1133 return 1;
1134}
1135
1136/*
1137 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1138 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1139 * the lock and this task is uninteresting. If we return nonzero, we have
1140 * released the lock and the system call should return.
1141 */
1142static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1143{
1144 int state, status;
1145 pid_t pid = task_pid_vnr(p);
1146 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1147 struct waitid_info *infop;
1148
1149 if (!likely(wo->wo_flags & WEXITED))
1150 return 0;
1151
1152 if (unlikely(wo->wo_flags & WNOWAIT)) {
1153 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1154 ? p->signal->group_exit_code : p->exit_code;
1155 get_task_struct(p);
1156 read_unlock(&tasklist_lock);
1157 sched_annotate_sleep();
1158 if (wo->wo_rusage)
1159 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1160 put_task_struct(p);
1161 goto out_info;
1162 }
1163 /*
1164 * Move the task's state to DEAD/TRACE, only one thread can do this.
1165 */
1166 state = (ptrace_reparented(p) && thread_group_leader(p)) ?
1167 EXIT_TRACE : EXIT_DEAD;
1168 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1169 return 0;
1170 /*
1171 * We own this thread, nobody else can reap it.
1172 */
1173 read_unlock(&tasklist_lock);
1174 sched_annotate_sleep();
1175
1176 /*
1177 * Check thread_group_leader() to exclude the traced sub-threads.
1178 */
1179 if (state == EXIT_DEAD && thread_group_leader(p)) {
1180 struct signal_struct *sig = p->signal;
1181 struct signal_struct *psig = current->signal;
1182 unsigned long maxrss;
1183 u64 tgutime, tgstime;
1184
1185 /*
1186 * The resource counters for the group leader are in its
1187 * own task_struct. Those for dead threads in the group
1188 * are in its signal_struct, as are those for the child
1189 * processes it has previously reaped. All these
1190 * accumulate in the parent's signal_struct c* fields.
1191 *
1192 * We don't bother to take a lock here to protect these
1193 * p->signal fields because the whole thread group is dead
1194 * and nobody can change them.
1195 *
1196 * psig->stats_lock also protects us from our sub-threads
1197 * which can reap other children at the same time.
1198 *
1199 * We use thread_group_cputime_adjusted() to get times for
1200 * the thread group, which consolidates times for all threads
1201 * in the group including the group leader.
1202 */
1203 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1204 write_seqlock_irq(&psig->stats_lock);
1205 psig->cutime += tgutime + sig->cutime;
1206 psig->cstime += tgstime + sig->cstime;
1207 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1208 psig->cmin_flt +=
1209 p->min_flt + sig->min_flt + sig->cmin_flt;
1210 psig->cmaj_flt +=
1211 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1212 psig->cnvcsw +=
1213 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1214 psig->cnivcsw +=
1215 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1216 psig->cinblock +=
1217 task_io_get_inblock(p) +
1218 sig->inblock + sig->cinblock;
1219 psig->coublock +=
1220 task_io_get_oublock(p) +
1221 sig->oublock + sig->coublock;
1222 maxrss = max(sig->maxrss, sig->cmaxrss);
1223 if (psig->cmaxrss < maxrss)
1224 psig->cmaxrss = maxrss;
1225 task_io_accounting_add(&psig->ioac, &p->ioac);
1226 task_io_accounting_add(&psig->ioac, &sig->ioac);
1227 write_sequnlock_irq(&psig->stats_lock);
1228 }
1229
1230 if (wo->wo_rusage)
1231 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1232 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1233 ? p->signal->group_exit_code : p->exit_code;
1234 wo->wo_stat = status;
1235
1236 if (state == EXIT_TRACE) {
1237 write_lock_irq(&tasklist_lock);
1238 /* We dropped tasklist, ptracer could die and untrace */
1239 ptrace_unlink(p);
1240
1241 /* If parent wants a zombie, don't release it now */
1242 state = EXIT_ZOMBIE;
1243 if (do_notify_parent(p, p->exit_signal))
1244 state = EXIT_DEAD;
1245 p->exit_state = state;
1246 write_unlock_irq(&tasklist_lock);
1247 }
1248 if (state == EXIT_DEAD)
1249 release_task(p);
1250
1251out_info:
1252 infop = wo->wo_info;
1253 if (infop) {
1254 if ((status & 0x7f) == 0) {
1255 infop->cause = CLD_EXITED;
1256 infop->status = status >> 8;
1257 } else {
1258 infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1259 infop->status = status & 0x7f;
1260 }
1261 infop->pid = pid;
1262 infop->uid = uid;
1263 }
1264
1265 return pid;
1266}
1267
1268static int *task_stopped_code(struct task_struct *p, bool ptrace)
1269{
1270 if (ptrace) {
1271 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING))
1272 return &p->exit_code;
1273 } else {
1274 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1275 return &p->signal->group_exit_code;
1276 }
1277 return NULL;
1278}
1279
1280/**
1281 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1282 * @wo: wait options
1283 * @ptrace: is the wait for ptrace
1284 * @p: task to wait for
1285 *
1286 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1287 *
1288 * CONTEXT:
1289 * read_lock(&tasklist_lock), which is released if return value is
1290 * non-zero. Also, grabs and releases @p->sighand->siglock.
1291 *
1292 * RETURNS:
1293 * 0 if wait condition didn't exist and search for other wait conditions
1294 * should continue. Non-zero return, -errno on failure and @p's pid on
1295 * success, implies that tasklist_lock is released and wait condition
1296 * search should terminate.
1297 */
1298static int wait_task_stopped(struct wait_opts *wo,
1299 int ptrace, struct task_struct *p)
1300{
1301 struct waitid_info *infop;
1302 int exit_code, *p_code, why;
1303 uid_t uid = 0; /* unneeded, required by compiler */
1304 pid_t pid;
1305
1306 /*
1307 * Traditionally we see ptrace'd stopped tasks regardless of options.
1308 */
1309 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1310 return 0;
1311
1312 if (!task_stopped_code(p, ptrace))
1313 return 0;
1314
1315 exit_code = 0;
1316 spin_lock_irq(&p->sighand->siglock);
1317
1318 p_code = task_stopped_code(p, ptrace);
1319 if (unlikely(!p_code))
1320 goto unlock_sig;
1321
1322 exit_code = *p_code;
1323 if (!exit_code)
1324 goto unlock_sig;
1325
1326 if (!unlikely(wo->wo_flags & WNOWAIT))
1327 *p_code = 0;
1328
1329 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1330unlock_sig:
1331 spin_unlock_irq(&p->sighand->siglock);
1332 if (!exit_code)
1333 return 0;
1334
1335 /*
1336 * Now we are pretty sure this task is interesting.
1337 * Make sure it doesn't get reaped out from under us while we
1338 * give up the lock and then examine it below. We don't want to
1339 * keep holding onto the tasklist_lock while we call getrusage and
1340 * possibly take page faults for user memory.
1341 */
1342 get_task_struct(p);
1343 pid = task_pid_vnr(p);
1344 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1345 read_unlock(&tasklist_lock);
1346 sched_annotate_sleep();
1347 if (wo->wo_rusage)
1348 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1349 put_task_struct(p);
1350
1351 if (likely(!(wo->wo_flags & WNOWAIT)))
1352 wo->wo_stat = (exit_code << 8) | 0x7f;
1353
1354 infop = wo->wo_info;
1355 if (infop) {
1356 infop->cause = why;
1357 infop->status = exit_code;
1358 infop->pid = pid;
1359 infop->uid = uid;
1360 }
1361 return pid;
1362}
1363
1364/*
1365 * Handle do_wait work for one task in a live, non-stopped state.
1366 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1367 * the lock and this task is uninteresting. If we return nonzero, we have
1368 * released the lock and the system call should return.
1369 */
1370static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1371{
1372 struct waitid_info *infop;
1373 pid_t pid;
1374 uid_t uid;
1375
1376 if (!unlikely(wo->wo_flags & WCONTINUED))
1377 return 0;
1378
1379 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1380 return 0;
1381
1382 spin_lock_irq(&p->sighand->siglock);
1383 /* Re-check with the lock held. */
1384 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1385 spin_unlock_irq(&p->sighand->siglock);
1386 return 0;
1387 }
1388 if (!unlikely(wo->wo_flags & WNOWAIT))
1389 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1390 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1391 spin_unlock_irq(&p->sighand->siglock);
1392
1393 pid = task_pid_vnr(p);
1394 get_task_struct(p);
1395 read_unlock(&tasklist_lock);
1396 sched_annotate_sleep();
1397 if (wo->wo_rusage)
1398 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1399 put_task_struct(p);
1400
1401 infop = wo->wo_info;
1402 if (!infop) {
1403 wo->wo_stat = 0xffff;
1404 } else {
1405 infop->cause = CLD_CONTINUED;
1406 infop->pid = pid;
1407 infop->uid = uid;
1408 infop->status = SIGCONT;
1409 }
1410 return pid;
1411}
1412
1413/*
1414 * Consider @p for a wait by @parent.
1415 *
1416 * -ECHILD should be in ->notask_error before the first call.
1417 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1418 * Returns zero if the search for a child should continue;
1419 * then ->notask_error is 0 if @p is an eligible child,
1420 * or still -ECHILD.
1421 */
1422static int wait_consider_task(struct wait_opts *wo, int ptrace,
1423 struct task_struct *p)
1424{
1425 /*
1426 * We can race with wait_task_zombie() from another thread.
1427 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1428 * can't confuse the checks below.
1429 */
1430 int exit_state = READ_ONCE(p->exit_state);
1431 int ret;
1432
1433 if (unlikely(exit_state == EXIT_DEAD))
1434 return 0;
1435
1436 ret = eligible_child(wo, ptrace, p);
1437 if (!ret)
1438 return ret;
1439
1440 if (unlikely(exit_state == EXIT_TRACE)) {
1441 /*
1442 * ptrace == 0 means we are the natural parent. In this case
1443 * we should clear notask_error, debugger will notify us.
1444 */
1445 if (likely(!ptrace))
1446 wo->notask_error = 0;
1447 return 0;
1448 }
1449
1450 if (likely(!ptrace) && unlikely(p->ptrace)) {
1451 /*
1452 * If it is traced by its real parent's group, just pretend
1453 * the caller is ptrace_do_wait() and reap this child if it
1454 * is zombie.
1455 *
1456 * This also hides group stop state from real parent; otherwise
1457 * a single stop can be reported twice as group and ptrace stop.
1458 * If a ptracer wants to distinguish these two events for its
1459 * own children it should create a separate process which takes
1460 * the role of real parent.
1461 */
1462 if (!ptrace_reparented(p))
1463 ptrace = 1;
1464 }
1465
1466 /* slay zombie? */
1467 if (exit_state == EXIT_ZOMBIE) {
1468 /* we don't reap group leaders with subthreads */
1469 if (!delay_group_leader(p)) {
1470 /*
1471 * A zombie ptracee is only visible to its ptracer.
1472 * Notification and reaping will be cascaded to the
1473 * real parent when the ptracer detaches.
1474 */
1475 if (unlikely(ptrace) || likely(!p->ptrace))
1476 return wait_task_zombie(wo, p);
1477 }
1478
1479 /*
1480 * Allow access to stopped/continued state via zombie by
1481 * falling through. Clearing of notask_error is complex.
1482 *
1483 * When !@ptrace:
1484 *
1485 * If WEXITED is set, notask_error should naturally be
1486 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1487 * so, if there are live subthreads, there are events to
1488 * wait for. If all subthreads are dead, it's still safe
1489 * to clear - this function will be called again in finite
1490 * amount time once all the subthreads are released and
1491 * will then return without clearing.
1492 *
1493 * When @ptrace:
1494 *
1495 * Stopped state is per-task and thus can't change once the
1496 * target task dies. Only continued and exited can happen.
1497 * Clear notask_error if WCONTINUED | WEXITED.
1498 */
1499 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1500 wo->notask_error = 0;
1501 } else {
1502 /*
1503 * @p is alive and it's gonna stop, continue or exit, so
1504 * there always is something to wait for.
1505 */
1506 wo->notask_error = 0;
1507 }
1508
1509 /*
1510 * Wait for stopped. Depending on @ptrace, different stopped state
1511 * is used and the two don't interact with each other.
1512 */
1513 ret = wait_task_stopped(wo, ptrace, p);
1514 if (ret)
1515 return ret;
1516
1517 /*
1518 * Wait for continued. There's only one continued state and the
1519 * ptracer can consume it which can confuse the real parent. Don't
1520 * use WCONTINUED from ptracer. You don't need or want it.
1521 */
1522 return wait_task_continued(wo, p);
1523}
1524
1525/*
1526 * Do the work of do_wait() for one thread in the group, @tsk.
1527 *
1528 * -ECHILD should be in ->notask_error before the first call.
1529 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1530 * Returns zero if the search for a child should continue; then
1531 * ->notask_error is 0 if there were any eligible children,
1532 * or still -ECHILD.
1533 */
1534static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1535{
1536 struct task_struct *p;
1537
1538 list_for_each_entry(p, &tsk->children, sibling) {
1539 int ret = wait_consider_task(wo, 0, p);
1540
1541 if (ret)
1542 return ret;
1543 }
1544
1545 return 0;
1546}
1547
1548static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1549{
1550 struct task_struct *p;
1551
1552 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1553 int ret = wait_consider_task(wo, 1, p);
1554
1555 if (ret)
1556 return ret;
1557 }
1558
1559 return 0;
1560}
1561
1562bool pid_child_should_wake(struct wait_opts *wo, struct task_struct *p)
1563{
1564 if (!eligible_pid(wo, p))
1565 return false;
1566
1567 if ((wo->wo_flags & __WNOTHREAD) && wo->child_wait.private != p->parent)
1568 return false;
1569
1570 return true;
1571}
1572
1573static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode,
1574 int sync, void *key)
1575{
1576 struct wait_opts *wo = container_of(wait, struct wait_opts,
1577 child_wait);
1578 struct task_struct *p = key;
1579
1580 if (pid_child_should_wake(wo, p))
1581 return default_wake_function(wait, mode, sync, key);
1582
1583 return 0;
1584}
1585
1586void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1587{
1588 __wake_up_sync_key(&parent->signal->wait_chldexit,
1589 TASK_INTERRUPTIBLE, p);
1590}
1591
1592static bool is_effectively_child(struct wait_opts *wo, bool ptrace,
1593 struct task_struct *target)
1594{
1595 struct task_struct *parent =
1596 !ptrace ? target->real_parent : target->parent;
1597
1598 return current == parent || (!(wo->wo_flags & __WNOTHREAD) &&
1599 same_thread_group(current, parent));
1600}
1601
1602/*
1603 * Optimization for waiting on PIDTYPE_PID. No need to iterate through child
1604 * and tracee lists to find the target task.
1605 */
1606static int do_wait_pid(struct wait_opts *wo)
1607{
1608 bool ptrace;
1609 struct task_struct *target;
1610 int retval;
1611
1612 ptrace = false;
1613 target = pid_task(wo->wo_pid, PIDTYPE_TGID);
1614 if (target && is_effectively_child(wo, ptrace, target)) {
1615 retval = wait_consider_task(wo, ptrace, target);
1616 if (retval)
1617 return retval;
1618 }
1619
1620 ptrace = true;
1621 target = pid_task(wo->wo_pid, PIDTYPE_PID);
1622 if (target && target->ptrace &&
1623 is_effectively_child(wo, ptrace, target)) {
1624 retval = wait_consider_task(wo, ptrace, target);
1625 if (retval)
1626 return retval;
1627 }
1628
1629 return 0;
1630}
1631
1632long __do_wait(struct wait_opts *wo)
1633{
1634 long retval;
1635
1636 /*
1637 * If there is nothing that can match our criteria, just get out.
1638 * We will clear ->notask_error to zero if we see any child that
1639 * might later match our criteria, even if we are not able to reap
1640 * it yet.
1641 */
1642 wo->notask_error = -ECHILD;
1643 if ((wo->wo_type < PIDTYPE_MAX) &&
1644 (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type)))
1645 goto notask;
1646
1647 read_lock(&tasklist_lock);
1648
1649 if (wo->wo_type == PIDTYPE_PID) {
1650 retval = do_wait_pid(wo);
1651 if (retval)
1652 return retval;
1653 } else {
1654 struct task_struct *tsk = current;
1655
1656 do {
1657 retval = do_wait_thread(wo, tsk);
1658 if (retval)
1659 return retval;
1660
1661 retval = ptrace_do_wait(wo, tsk);
1662 if (retval)
1663 return retval;
1664
1665 if (wo->wo_flags & __WNOTHREAD)
1666 break;
1667 } while_each_thread(current, tsk);
1668 }
1669 read_unlock(&tasklist_lock);
1670
1671notask:
1672 retval = wo->notask_error;
1673 if (!retval && !(wo->wo_flags & WNOHANG))
1674 return -ERESTARTSYS;
1675
1676 return retval;
1677}
1678
1679static long do_wait(struct wait_opts *wo)
1680{
1681 int retval;
1682
1683 trace_sched_process_wait(wo->wo_pid);
1684
1685 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1686 wo->child_wait.private = current;
1687 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1688
1689 do {
1690 set_current_state(TASK_INTERRUPTIBLE);
1691 retval = __do_wait(wo);
1692 if (retval != -ERESTARTSYS)
1693 break;
1694 if (signal_pending(current))
1695 break;
1696 schedule();
1697 } while (1);
1698
1699 __set_current_state(TASK_RUNNING);
1700 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1701 return retval;
1702}
1703
1704int kernel_waitid_prepare(struct wait_opts *wo, int which, pid_t upid,
1705 struct waitid_info *infop, int options,
1706 struct rusage *ru)
1707{
1708 unsigned int f_flags = 0;
1709 struct pid *pid = NULL;
1710 enum pid_type type;
1711
1712 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
1713 __WNOTHREAD|__WCLONE|__WALL))
1714 return -EINVAL;
1715 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1716 return -EINVAL;
1717
1718 switch (which) {
1719 case P_ALL:
1720 type = PIDTYPE_MAX;
1721 break;
1722 case P_PID:
1723 type = PIDTYPE_PID;
1724 if (upid <= 0)
1725 return -EINVAL;
1726
1727 pid = find_get_pid(upid);
1728 break;
1729 case P_PGID:
1730 type = PIDTYPE_PGID;
1731 if (upid < 0)
1732 return -EINVAL;
1733
1734 if (upid)
1735 pid = find_get_pid(upid);
1736 else
1737 pid = get_task_pid(current, PIDTYPE_PGID);
1738 break;
1739 case P_PIDFD:
1740 type = PIDTYPE_PID;
1741 if (upid < 0)
1742 return -EINVAL;
1743
1744 pid = pidfd_get_pid(upid, &f_flags);
1745 if (IS_ERR(pid))
1746 return PTR_ERR(pid);
1747
1748 break;
1749 default:
1750 return -EINVAL;
1751 }
1752
1753 wo->wo_type = type;
1754 wo->wo_pid = pid;
1755 wo->wo_flags = options;
1756 wo->wo_info = infop;
1757 wo->wo_rusage = ru;
1758 if (f_flags & O_NONBLOCK)
1759 wo->wo_flags |= WNOHANG;
1760
1761 return 0;
1762}
1763
1764static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
1765 int options, struct rusage *ru)
1766{
1767 struct wait_opts wo;
1768 long ret;
1769
1770 ret = kernel_waitid_prepare(&wo, which, upid, infop, options, ru);
1771 if (ret)
1772 return ret;
1773
1774 ret = do_wait(&wo);
1775 if (!ret && !(options & WNOHANG) && (wo.wo_flags & WNOHANG))
1776 ret = -EAGAIN;
1777
1778 put_pid(wo.wo_pid);
1779 return ret;
1780}
1781
1782SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1783 infop, int, options, struct rusage __user *, ru)
1784{
1785 struct rusage r;
1786 struct waitid_info info = {.status = 0};
1787 long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
1788 int signo = 0;
1789
1790 if (err > 0) {
1791 signo = SIGCHLD;
1792 err = 0;
1793 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1794 return -EFAULT;
1795 }
1796 if (!infop)
1797 return err;
1798
1799 if (!user_write_access_begin(infop, sizeof(*infop)))
1800 return -EFAULT;
1801
1802 unsafe_put_user(signo, &infop->si_signo, Efault);
1803 unsafe_put_user(0, &infop->si_errno, Efault);
1804 unsafe_put_user(info.cause, &infop->si_code, Efault);
1805 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1806 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1807 unsafe_put_user(info.status, &infop->si_status, Efault);
1808 user_write_access_end();
1809 return err;
1810Efault:
1811 user_write_access_end();
1812 return -EFAULT;
1813}
1814
1815long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
1816 struct rusage *ru)
1817{
1818 struct wait_opts wo;
1819 struct pid *pid = NULL;
1820 enum pid_type type;
1821 long ret;
1822
1823 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1824 __WNOTHREAD|__WCLONE|__WALL))
1825 return -EINVAL;
1826
1827 /* -INT_MIN is not defined */
1828 if (upid == INT_MIN)
1829 return -ESRCH;
1830
1831 if (upid == -1)
1832 type = PIDTYPE_MAX;
1833 else if (upid < 0) {
1834 type = PIDTYPE_PGID;
1835 pid = find_get_pid(-upid);
1836 } else if (upid == 0) {
1837 type = PIDTYPE_PGID;
1838 pid = get_task_pid(current, PIDTYPE_PGID);
1839 } else /* upid > 0 */ {
1840 type = PIDTYPE_PID;
1841 pid = find_get_pid(upid);
1842 }
1843
1844 wo.wo_type = type;
1845 wo.wo_pid = pid;
1846 wo.wo_flags = options | WEXITED;
1847 wo.wo_info = NULL;
1848 wo.wo_stat = 0;
1849 wo.wo_rusage = ru;
1850 ret = do_wait(&wo);
1851 put_pid(pid);
1852 if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
1853 ret = -EFAULT;
1854
1855 return ret;
1856}
1857
1858int kernel_wait(pid_t pid, int *stat)
1859{
1860 struct wait_opts wo = {
1861 .wo_type = PIDTYPE_PID,
1862 .wo_pid = find_get_pid(pid),
1863 .wo_flags = WEXITED,
1864 };
1865 int ret;
1866
1867 ret = do_wait(&wo);
1868 if (ret > 0 && wo.wo_stat)
1869 *stat = wo.wo_stat;
1870 put_pid(wo.wo_pid);
1871 return ret;
1872}
1873
1874SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1875 int, options, struct rusage __user *, ru)
1876{
1877 struct rusage r;
1878 long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL);
1879
1880 if (err > 0) {
1881 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1882 return -EFAULT;
1883 }
1884 return err;
1885}
1886
1887#ifdef __ARCH_WANT_SYS_WAITPID
1888
1889/*
1890 * sys_waitpid() remains for compatibility. waitpid() should be
1891 * implemented by calling sys_wait4() from libc.a.
1892 */
1893SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1894{
1895 return kernel_wait4(pid, stat_addr, options, NULL);
1896}
1897
1898#endif
1899
1900#ifdef CONFIG_COMPAT
1901COMPAT_SYSCALL_DEFINE4(wait4,
1902 compat_pid_t, pid,
1903 compat_uint_t __user *, stat_addr,
1904 int, options,
1905 struct compat_rusage __user *, ru)
1906{
1907 struct rusage r;
1908 long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL);
1909 if (err > 0) {
1910 if (ru && put_compat_rusage(&r, ru))
1911 return -EFAULT;
1912 }
1913 return err;
1914}
1915
1916COMPAT_SYSCALL_DEFINE5(waitid,
1917 int, which, compat_pid_t, pid,
1918 struct compat_siginfo __user *, infop, int, options,
1919 struct compat_rusage __user *, uru)
1920{
1921 struct rusage ru;
1922 struct waitid_info info = {.status = 0};
1923 long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);
1924 int signo = 0;
1925 if (err > 0) {
1926 signo = SIGCHLD;
1927 err = 0;
1928 if (uru) {
1929 /* kernel_waitid() overwrites everything in ru */
1930 if (COMPAT_USE_64BIT_TIME)
1931 err = copy_to_user(uru, &ru, sizeof(ru));
1932 else
1933 err = put_compat_rusage(&ru, uru);
1934 if (err)
1935 return -EFAULT;
1936 }
1937 }
1938
1939 if (!infop)
1940 return err;
1941
1942 if (!user_write_access_begin(infop, sizeof(*infop)))
1943 return -EFAULT;
1944
1945 unsafe_put_user(signo, &infop->si_signo, Efault);
1946 unsafe_put_user(0, &infop->si_errno, Efault);
1947 unsafe_put_user(info.cause, &infop->si_code, Efault);
1948 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1949 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1950 unsafe_put_user(info.status, &infop->si_status, Efault);
1951 user_write_access_end();
1952 return err;
1953Efault:
1954 user_write_access_end();
1955 return -EFAULT;
1956}
1957#endif
1958
1959/*
1960 * This needs to be __function_aligned as GCC implicitly makes any
1961 * implementation of abort() cold and drops alignment specified by
1962 * -falign-functions=N.
1963 *
1964 * See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88345#c11
1965 */
1966__weak __function_aligned void abort(void)
1967{
1968 BUG();
1969
1970 /* if that doesn't kill us, halt */
1971 panic("Oops failed to kill thread");
1972}
1973EXPORT_SYMBOL(abort);