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