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