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1/*
2 * linux/kernel/exit.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7#include <linux/mm.h>
8#include <linux/slab.h>
9#include <linux/interrupt.h>
10#include <linux/module.h>
11#include <linux/capability.h>
12#include <linux/completion.h>
13#include <linux/personality.h>
14#include <linux/tty.h>
15#include <linux/iocontext.h>
16#include <linux/key.h>
17#include <linux/security.h>
18#include <linux/cpu.h>
19#include <linux/acct.h>
20#include <linux/tsacct_kern.h>
21#include <linux/file.h>
22#include <linux/fdtable.h>
23#include <linux/freezer.h>
24#include <linux/binfmts.h>
25#include <linux/nsproxy.h>
26#include <linux/pid_namespace.h>
27#include <linux/ptrace.h>
28#include <linux/profile.h>
29#include <linux/mount.h>
30#include <linux/proc_fs.h>
31#include <linux/kthread.h>
32#include <linux/mempolicy.h>
33#include <linux/taskstats_kern.h>
34#include <linux/delayacct.h>
35#include <linux/cgroup.h>
36#include <linux/syscalls.h>
37#include <linux/signal.h>
38#include <linux/posix-timers.h>
39#include <linux/cn_proc.h>
40#include <linux/mutex.h>
41#include <linux/futex.h>
42#include <linux/pipe_fs_i.h>
43#include <linux/audit.h> /* for audit_free() */
44#include <linux/resource.h>
45#include <linux/blkdev.h>
46#include <linux/task_io_accounting_ops.h>
47#include <linux/tracehook.h>
48#include <linux/fs_struct.h>
49#include <linux/init_task.h>
50#include <linux/perf_event.h>
51#include <trace/events/sched.h>
52#include <linux/hw_breakpoint.h>
53#include <linux/oom.h>
54#include <linux/writeback.h>
55#include <linux/shm.h>
56
57#include <asm/uaccess.h>
58#include <asm/unistd.h>
59#include <asm/pgtable.h>
60#include <asm/mmu_context.h>
61
62static void exit_mm(struct task_struct * tsk);
63
64static void __unhash_process(struct task_struct *p, bool group_dead)
65{
66 nr_threads--;
67 detach_pid(p, PIDTYPE_PID);
68 if (group_dead) {
69 detach_pid(p, PIDTYPE_PGID);
70 detach_pid(p, PIDTYPE_SID);
71
72 list_del_rcu(&p->tasks);
73 list_del_init(&p->sibling);
74 __this_cpu_dec(process_counts);
75 }
76 list_del_rcu(&p->thread_group);
77 list_del_rcu(&p->thread_node);
78}
79
80/*
81 * This function expects the tasklist_lock write-locked.
82 */
83static void __exit_signal(struct task_struct *tsk)
84{
85 struct signal_struct *sig = tsk->signal;
86 bool group_dead = thread_group_leader(tsk);
87 struct sighand_struct *sighand;
88 struct tty_struct *uninitialized_var(tty);
89 cputime_t utime, stime;
90
91 sighand = rcu_dereference_check(tsk->sighand,
92 lockdep_tasklist_lock_is_held());
93 spin_lock(&sighand->siglock);
94
95 posix_cpu_timers_exit(tsk);
96 if (group_dead) {
97 posix_cpu_timers_exit_group(tsk);
98 tty = sig->tty;
99 sig->tty = NULL;
100 } else {
101 /*
102 * This can only happen if the caller is de_thread().
103 * FIXME: this is the temporary hack, we should teach
104 * posix-cpu-timers to handle this case correctly.
105 */
106 if (unlikely(has_group_leader_pid(tsk)))
107 posix_cpu_timers_exit_group(tsk);
108
109 /*
110 * If there is any task waiting for the group exit
111 * then notify it:
112 */
113 if (sig->notify_count > 0 && !--sig->notify_count)
114 wake_up_process(sig->group_exit_task);
115
116 if (tsk == sig->curr_target)
117 sig->curr_target = next_thread(tsk);
118 /*
119 * Accumulate here the counters for all threads but the
120 * group leader as they die, so they can be added into
121 * the process-wide totals when those are taken.
122 * The group leader stays around as a zombie as long
123 * as there are other threads. When it gets reaped,
124 * the exit.c code will add its counts into these totals.
125 * We won't ever get here for the group leader, since it
126 * will have been the last reference on the signal_struct.
127 */
128 task_cputime(tsk, &utime, &stime);
129 sig->utime += utime;
130 sig->stime += stime;
131 sig->gtime += task_gtime(tsk);
132 sig->min_flt += tsk->min_flt;
133 sig->maj_flt += tsk->maj_flt;
134 sig->nvcsw += tsk->nvcsw;
135 sig->nivcsw += tsk->nivcsw;
136 sig->inblock += task_io_get_inblock(tsk);
137 sig->oublock += task_io_get_oublock(tsk);
138 task_io_accounting_add(&sig->ioac, &tsk->ioac);
139 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
140 }
141
142 sig->nr_threads--;
143 __unhash_process(tsk, group_dead);
144
145 /*
146 * Do this under ->siglock, we can race with another thread
147 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
148 */
149 flush_sigqueue(&tsk->pending);
150 tsk->sighand = NULL;
151 spin_unlock(&sighand->siglock);
152
153 __cleanup_sighand(sighand);
154 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
155 if (group_dead) {
156 flush_sigqueue(&sig->shared_pending);
157 tty_kref_put(tty);
158 }
159}
160
161static void delayed_put_task_struct(struct rcu_head *rhp)
162{
163 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
164
165 perf_event_delayed_put(tsk);
166 trace_sched_process_free(tsk);
167 put_task_struct(tsk);
168}
169
170
171void release_task(struct task_struct * p)
172{
173 struct task_struct *leader;
174 int zap_leader;
175repeat:
176 /* don't need to get the RCU readlock here - the process is dead and
177 * can't be modifying its own credentials. But shut RCU-lockdep up */
178 rcu_read_lock();
179 atomic_dec(&__task_cred(p)->user->processes);
180 rcu_read_unlock();
181
182 proc_flush_task(p);
183
184 write_lock_irq(&tasklist_lock);
185 ptrace_release_task(p);
186 __exit_signal(p);
187
188 /*
189 * If we are the last non-leader member of the thread
190 * group, and the leader is zombie, then notify the
191 * group leader's parent process. (if it wants notification.)
192 */
193 zap_leader = 0;
194 leader = p->group_leader;
195 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
196 /*
197 * If we were the last child thread and the leader has
198 * exited already, and the leader's parent ignores SIGCHLD,
199 * then we are the one who should release the leader.
200 */
201 zap_leader = do_notify_parent(leader, leader->exit_signal);
202 if (zap_leader)
203 leader->exit_state = EXIT_DEAD;
204 }
205
206 write_unlock_irq(&tasklist_lock);
207 release_thread(p);
208 call_rcu(&p->rcu, delayed_put_task_struct);
209
210 p = leader;
211 if (unlikely(zap_leader))
212 goto repeat;
213}
214
215/*
216 * This checks not only the pgrp, but falls back on the pid if no
217 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
218 * without this...
219 *
220 * The caller must hold rcu lock or the tasklist lock.
221 */
222struct pid *session_of_pgrp(struct pid *pgrp)
223{
224 struct task_struct *p;
225 struct pid *sid = NULL;
226
227 p = pid_task(pgrp, PIDTYPE_PGID);
228 if (p == NULL)
229 p = pid_task(pgrp, PIDTYPE_PID);
230 if (p != NULL)
231 sid = task_session(p);
232
233 return sid;
234}
235
236/*
237 * Determine if a process group is "orphaned", according to the POSIX
238 * definition in 2.2.2.52. Orphaned process groups are not to be affected
239 * by terminal-generated stop signals. Newly orphaned process groups are
240 * to receive a SIGHUP and a SIGCONT.
241 *
242 * "I ask you, have you ever known what it is to be an orphan?"
243 */
244static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
245{
246 struct task_struct *p;
247
248 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
249 if ((p == ignored_task) ||
250 (p->exit_state && thread_group_empty(p)) ||
251 is_global_init(p->real_parent))
252 continue;
253
254 if (task_pgrp(p->real_parent) != pgrp &&
255 task_session(p->real_parent) == task_session(p))
256 return 0;
257 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
258
259 return 1;
260}
261
262int is_current_pgrp_orphaned(void)
263{
264 int retval;
265
266 read_lock(&tasklist_lock);
267 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
268 read_unlock(&tasklist_lock);
269
270 return retval;
271}
272
273static bool has_stopped_jobs(struct pid *pgrp)
274{
275 struct task_struct *p;
276
277 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
278 if (p->signal->flags & SIGNAL_STOP_STOPPED)
279 return true;
280 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
281
282 return false;
283}
284
285/*
286 * Check to see if any process groups have become orphaned as
287 * a result of our exiting, and if they have any stopped jobs,
288 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
289 */
290static void
291kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
292{
293 struct pid *pgrp = task_pgrp(tsk);
294 struct task_struct *ignored_task = tsk;
295
296 if (!parent)
297 /* exit: our father is in a different pgrp than
298 * we are and we were the only connection outside.
299 */
300 parent = tsk->real_parent;
301 else
302 /* reparent: our child is in a different pgrp than
303 * we are, and it was the only connection outside.
304 */
305 ignored_task = NULL;
306
307 if (task_pgrp(parent) != pgrp &&
308 task_session(parent) == task_session(tsk) &&
309 will_become_orphaned_pgrp(pgrp, ignored_task) &&
310 has_stopped_jobs(pgrp)) {
311 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
312 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
313 }
314}
315
316/*
317 * Let kernel threads use this to say that they allow a certain signal.
318 * Must not be used if kthread was cloned with CLONE_SIGHAND.
319 */
320int allow_signal(int sig)
321{
322 if (!valid_signal(sig) || sig < 1)
323 return -EINVAL;
324
325 spin_lock_irq(¤t->sighand->siglock);
326 /* This is only needed for daemonize()'ed kthreads */
327 sigdelset(¤t->blocked, sig);
328 /*
329 * Kernel threads handle their own signals. Let the signal code
330 * know it'll be handled, so that they don't get converted to
331 * SIGKILL or just silently dropped.
332 */
333 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
334 recalc_sigpending();
335 spin_unlock_irq(¤t->sighand->siglock);
336 return 0;
337}
338
339EXPORT_SYMBOL(allow_signal);
340
341int disallow_signal(int sig)
342{
343 if (!valid_signal(sig) || sig < 1)
344 return -EINVAL;
345
346 spin_lock_irq(¤t->sighand->siglock);
347 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
348 recalc_sigpending();
349 spin_unlock_irq(¤t->sighand->siglock);
350 return 0;
351}
352
353EXPORT_SYMBOL(disallow_signal);
354
355#ifdef CONFIG_MM_OWNER
356/*
357 * A task is exiting. If it owned this mm, find a new owner for the mm.
358 */
359void mm_update_next_owner(struct mm_struct *mm)
360{
361 struct task_struct *c, *g, *p = current;
362
363retry:
364 /*
365 * If the exiting or execing task is not the owner, it's
366 * someone else's problem.
367 */
368 if (mm->owner != p)
369 return;
370 /*
371 * The current owner is exiting/execing and there are no other
372 * candidates. Do not leave the mm pointing to a possibly
373 * freed task structure.
374 */
375 if (atomic_read(&mm->mm_users) <= 1) {
376 mm->owner = NULL;
377 return;
378 }
379
380 read_lock(&tasklist_lock);
381 /*
382 * Search in the children
383 */
384 list_for_each_entry(c, &p->children, sibling) {
385 if (c->mm == mm)
386 goto assign_new_owner;
387 }
388
389 /*
390 * Search in the siblings
391 */
392 list_for_each_entry(c, &p->real_parent->children, sibling) {
393 if (c->mm == mm)
394 goto assign_new_owner;
395 }
396
397 /*
398 * Search through everything else. We should not get
399 * here often
400 */
401 do_each_thread(g, c) {
402 if (c->mm == mm)
403 goto assign_new_owner;
404 } while_each_thread(g, c);
405
406 read_unlock(&tasklist_lock);
407 /*
408 * We found no owner yet mm_users > 1: this implies that we are
409 * most likely racing with swapoff (try_to_unuse()) or /proc or
410 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
411 */
412 mm->owner = NULL;
413 return;
414
415assign_new_owner:
416 BUG_ON(c == p);
417 get_task_struct(c);
418 /*
419 * The task_lock protects c->mm from changing.
420 * We always want mm->owner->mm == mm
421 */
422 task_lock(c);
423 /*
424 * Delay read_unlock() till we have the task_lock()
425 * to ensure that c does not slip away underneath us
426 */
427 read_unlock(&tasklist_lock);
428 if (c->mm != mm) {
429 task_unlock(c);
430 put_task_struct(c);
431 goto retry;
432 }
433 mm->owner = c;
434 task_unlock(c);
435 put_task_struct(c);
436}
437#endif /* CONFIG_MM_OWNER */
438
439/*
440 * Turn us into a lazy TLB process if we
441 * aren't already..
442 */
443static void exit_mm(struct task_struct * tsk)
444{
445 struct mm_struct *mm = tsk->mm;
446 struct core_state *core_state;
447
448 mm_release(tsk, mm);
449 if (!mm)
450 return;
451 sync_mm_rss(mm);
452 /*
453 * Serialize with any possible pending coredump.
454 * We must hold mmap_sem around checking core_state
455 * and clearing tsk->mm. The core-inducing thread
456 * will increment ->nr_threads for each thread in the
457 * group with ->mm != NULL.
458 */
459 down_read(&mm->mmap_sem);
460 core_state = mm->core_state;
461 if (core_state) {
462 struct core_thread self;
463 up_read(&mm->mmap_sem);
464
465 self.task = tsk;
466 self.next = xchg(&core_state->dumper.next, &self);
467 /*
468 * Implies mb(), the result of xchg() must be visible
469 * to core_state->dumper.
470 */
471 if (atomic_dec_and_test(&core_state->nr_threads))
472 complete(&core_state->startup);
473
474 for (;;) {
475 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
476 if (!self.task) /* see coredump_finish() */
477 break;
478 freezable_schedule();
479 }
480 __set_task_state(tsk, TASK_RUNNING);
481 down_read(&mm->mmap_sem);
482 }
483 atomic_inc(&mm->mm_count);
484 BUG_ON(mm != tsk->active_mm);
485 /* more a memory barrier than a real lock */
486 task_lock(tsk);
487 tsk->mm = NULL;
488 up_read(&mm->mmap_sem);
489 enter_lazy_tlb(mm, current);
490 task_unlock(tsk);
491 mm_update_next_owner(mm);
492 mmput(mm);
493}
494
495/*
496 * When we die, we re-parent all our children, and try to:
497 * 1. give them to another thread in our thread group, if such a member exists
498 * 2. give it to the first ancestor process which prctl'd itself as a
499 * child_subreaper for its children (like a service manager)
500 * 3. give it to the init process (PID 1) in our pid namespace
501 */
502static struct task_struct *find_new_reaper(struct task_struct *father)
503 __releases(&tasklist_lock)
504 __acquires(&tasklist_lock)
505{
506 struct pid_namespace *pid_ns = task_active_pid_ns(father);
507 struct task_struct *thread;
508
509 thread = father;
510 while_each_thread(father, thread) {
511 if (thread->flags & PF_EXITING)
512 continue;
513 if (unlikely(pid_ns->child_reaper == father))
514 pid_ns->child_reaper = thread;
515 return thread;
516 }
517
518 if (unlikely(pid_ns->child_reaper == father)) {
519 write_unlock_irq(&tasklist_lock);
520 if (unlikely(pid_ns == &init_pid_ns)) {
521 panic("Attempted to kill init! exitcode=0x%08x\n",
522 father->signal->group_exit_code ?:
523 father->exit_code);
524 }
525
526 zap_pid_ns_processes(pid_ns);
527 write_lock_irq(&tasklist_lock);
528 } else if (father->signal->has_child_subreaper) {
529 struct task_struct *reaper;
530
531 /*
532 * Find the first ancestor marked as child_subreaper.
533 * Note that the code below checks same_thread_group(reaper,
534 * pid_ns->child_reaper). This is what we need to DTRT in a
535 * PID namespace. However we still need the check above, see
536 * http://marc.info/?l=linux-kernel&m=131385460420380
537 */
538 for (reaper = father->real_parent;
539 reaper != &init_task;
540 reaper = reaper->real_parent) {
541 if (same_thread_group(reaper, pid_ns->child_reaper))
542 break;
543 if (!reaper->signal->is_child_subreaper)
544 continue;
545 thread = reaper;
546 do {
547 if (!(thread->flags & PF_EXITING))
548 return reaper;
549 } while_each_thread(reaper, thread);
550 }
551 }
552
553 return pid_ns->child_reaper;
554}
555
556/*
557* Any that need to be release_task'd are put on the @dead list.
558 */
559static void reparent_leader(struct task_struct *father, struct task_struct *p,
560 struct list_head *dead)
561{
562 list_move_tail(&p->sibling, &p->real_parent->children);
563
564 if (p->exit_state == EXIT_DEAD)
565 return;
566 /*
567 * If this is a threaded reparent there is no need to
568 * notify anyone anything has happened.
569 */
570 if (same_thread_group(p->real_parent, father))
571 return;
572
573 /* We don't want people slaying init. */
574 p->exit_signal = SIGCHLD;
575
576 /* If it has exited notify the new parent about this child's death. */
577 if (!p->ptrace &&
578 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
579 if (do_notify_parent(p, p->exit_signal)) {
580 p->exit_state = EXIT_DEAD;
581 list_move_tail(&p->sibling, dead);
582 }
583 }
584
585 kill_orphaned_pgrp(p, father);
586}
587
588static void forget_original_parent(struct task_struct *father)
589{
590 struct task_struct *p, *n, *reaper;
591 LIST_HEAD(dead_children);
592
593 write_lock_irq(&tasklist_lock);
594 /*
595 * Note that exit_ptrace() and find_new_reaper() might
596 * drop tasklist_lock and reacquire it.
597 */
598 exit_ptrace(father);
599 reaper = find_new_reaper(father);
600
601 list_for_each_entry_safe(p, n, &father->children, sibling) {
602 struct task_struct *t = p;
603 do {
604 t->real_parent = reaper;
605 if (t->parent == father) {
606 BUG_ON(t->ptrace);
607 t->parent = t->real_parent;
608 }
609 if (t->pdeath_signal)
610 group_send_sig_info(t->pdeath_signal,
611 SEND_SIG_NOINFO, t);
612 } while_each_thread(p, t);
613 reparent_leader(father, p, &dead_children);
614 }
615 write_unlock_irq(&tasklist_lock);
616
617 BUG_ON(!list_empty(&father->children));
618
619 list_for_each_entry_safe(p, n, &dead_children, sibling) {
620 list_del_init(&p->sibling);
621 release_task(p);
622 }
623}
624
625/*
626 * Send signals to all our closest relatives so that they know
627 * to properly mourn us..
628 */
629static void exit_notify(struct task_struct *tsk, int group_dead)
630{
631 bool autoreap;
632
633 /*
634 * This does two things:
635 *
636 * A. Make init inherit all the child processes
637 * B. Check to see if any process groups have become orphaned
638 * as a result of our exiting, and if they have any stopped
639 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
640 */
641 forget_original_parent(tsk);
642
643 write_lock_irq(&tasklist_lock);
644 if (group_dead)
645 kill_orphaned_pgrp(tsk->group_leader, NULL);
646
647 if (unlikely(tsk->ptrace)) {
648 int sig = thread_group_leader(tsk) &&
649 thread_group_empty(tsk) &&
650 !ptrace_reparented(tsk) ?
651 tsk->exit_signal : SIGCHLD;
652 autoreap = do_notify_parent(tsk, sig);
653 } else if (thread_group_leader(tsk)) {
654 autoreap = thread_group_empty(tsk) &&
655 do_notify_parent(tsk, tsk->exit_signal);
656 } else {
657 autoreap = true;
658 }
659
660 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
661
662 /* mt-exec, de_thread() is waiting for group leader */
663 if (unlikely(tsk->signal->notify_count < 0))
664 wake_up_process(tsk->signal->group_exit_task);
665 write_unlock_irq(&tasklist_lock);
666
667 /* If the process is dead, release it - nobody will wait for it */
668 if (autoreap)
669 release_task(tsk);
670}
671
672#ifdef CONFIG_DEBUG_STACK_USAGE
673static void check_stack_usage(void)
674{
675 static DEFINE_SPINLOCK(low_water_lock);
676 static int lowest_to_date = THREAD_SIZE;
677 unsigned long free;
678
679 free = stack_not_used(current);
680
681 if (free >= lowest_to_date)
682 return;
683
684 spin_lock(&low_water_lock);
685 if (free < lowest_to_date) {
686 printk(KERN_WARNING "%s (%d) used greatest stack depth: "
687 "%lu bytes left\n",
688 current->comm, task_pid_nr(current), free);
689 lowest_to_date = free;
690 }
691 spin_unlock(&low_water_lock);
692}
693#else
694static inline void check_stack_usage(void) {}
695#endif
696
697void do_exit(long code)
698{
699 struct task_struct *tsk = current;
700 int group_dead;
701
702 profile_task_exit(tsk);
703
704 WARN_ON(blk_needs_flush_plug(tsk));
705
706 if (unlikely(in_interrupt()))
707 panic("Aiee, killing interrupt handler!");
708 if (unlikely(!tsk->pid))
709 panic("Attempted to kill the idle task!");
710
711 /*
712 * If do_exit is called because this processes oopsed, it's possible
713 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
714 * continuing. Amongst other possible reasons, this is to prevent
715 * mm_release()->clear_child_tid() from writing to a user-controlled
716 * kernel address.
717 */
718 set_fs(USER_DS);
719
720 ptrace_event(PTRACE_EVENT_EXIT, code);
721
722 validate_creds_for_do_exit(tsk);
723
724 /*
725 * We're taking recursive faults here in do_exit. Safest is to just
726 * leave this task alone and wait for reboot.
727 */
728 if (unlikely(tsk->flags & PF_EXITING)) {
729 printk(KERN_ALERT
730 "Fixing recursive fault but reboot is needed!\n");
731 /*
732 * We can do this unlocked here. The futex code uses
733 * this flag just to verify whether the pi state
734 * cleanup has been done or not. In the worst case it
735 * loops once more. We pretend that the cleanup was
736 * done as there is no way to return. Either the
737 * OWNER_DIED bit is set by now or we push the blocked
738 * task into the wait for ever nirwana as well.
739 */
740 tsk->flags |= PF_EXITPIDONE;
741 set_current_state(TASK_UNINTERRUPTIBLE);
742 schedule();
743 }
744
745 exit_signals(tsk); /* sets PF_EXITING */
746 /*
747 * tsk->flags are checked in the futex code to protect against
748 * an exiting task cleaning up the robust pi futexes.
749 */
750 smp_mb();
751 raw_spin_unlock_wait(&tsk->pi_lock);
752
753 if (unlikely(in_atomic()))
754 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
755 current->comm, task_pid_nr(current),
756 preempt_count());
757
758 acct_update_integrals(tsk);
759 /* sync mm's RSS info before statistics gathering */
760 if (tsk->mm)
761 sync_mm_rss(tsk->mm);
762 group_dead = atomic_dec_and_test(&tsk->signal->live);
763 if (group_dead) {
764 hrtimer_cancel(&tsk->signal->real_timer);
765 exit_itimers(tsk->signal);
766 if (tsk->mm)
767 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
768 }
769 acct_collect(code, group_dead);
770 if (group_dead)
771 tty_audit_exit();
772 audit_free(tsk);
773
774 tsk->exit_code = code;
775 taskstats_exit(tsk, group_dead);
776
777 exit_mm(tsk);
778
779 if (group_dead)
780 acct_process();
781 trace_sched_process_exit(tsk);
782
783 exit_sem(tsk);
784 exit_shm(tsk);
785 exit_files(tsk);
786 exit_fs(tsk);
787 if (group_dead)
788 disassociate_ctty(1);
789 exit_task_namespaces(tsk);
790 exit_task_work(tsk);
791 exit_thread();
792
793 /*
794 * Flush inherited counters to the parent - before the parent
795 * gets woken up by child-exit notifications.
796 *
797 * because of cgroup mode, must be called before cgroup_exit()
798 */
799 perf_event_exit_task(tsk);
800
801 cgroup_exit(tsk);
802
803 module_put(task_thread_info(tsk)->exec_domain->module);
804
805 /*
806 * FIXME: do that only when needed, using sched_exit tracepoint
807 */
808 flush_ptrace_hw_breakpoint(tsk);
809
810 exit_notify(tsk, group_dead);
811 proc_exit_connector(tsk);
812#ifdef CONFIG_NUMA
813 task_lock(tsk);
814 mpol_put(tsk->mempolicy);
815 tsk->mempolicy = NULL;
816 task_unlock(tsk);
817#endif
818#ifdef CONFIG_FUTEX
819 if (unlikely(current->pi_state_cache))
820 kfree(current->pi_state_cache);
821#endif
822 /*
823 * Make sure we are holding no locks:
824 */
825 debug_check_no_locks_held();
826 /*
827 * We can do this unlocked here. The futex code uses this flag
828 * just to verify whether the pi state cleanup has been done
829 * or not. In the worst case it loops once more.
830 */
831 tsk->flags |= PF_EXITPIDONE;
832
833 if (tsk->io_context)
834 exit_io_context(tsk);
835
836 if (tsk->splice_pipe)
837 free_pipe_info(tsk->splice_pipe);
838
839 if (tsk->task_frag.page)
840 put_page(tsk->task_frag.page);
841
842 validate_creds_for_do_exit(tsk);
843
844 check_stack_usage();
845 preempt_disable();
846 if (tsk->nr_dirtied)
847 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
848 exit_rcu();
849
850 /*
851 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
852 * when the following two conditions become true.
853 * - There is race condition of mmap_sem (It is acquired by
854 * exit_mm()), and
855 * - SMI occurs before setting TASK_RUNINNG.
856 * (or hypervisor of virtual machine switches to other guest)
857 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
858 *
859 * To avoid it, we have to wait for releasing tsk->pi_lock which
860 * is held by try_to_wake_up()
861 */
862 smp_mb();
863 raw_spin_unlock_wait(&tsk->pi_lock);
864
865 /* causes final put_task_struct in finish_task_switch(). */
866 tsk->state = TASK_DEAD;
867 tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */
868 schedule();
869 BUG();
870 /* Avoid "noreturn function does return". */
871 for (;;)
872 cpu_relax(); /* For when BUG is null */
873}
874
875EXPORT_SYMBOL_GPL(do_exit);
876
877void complete_and_exit(struct completion *comp, long code)
878{
879 if (comp)
880 complete(comp);
881
882 do_exit(code);
883}
884
885EXPORT_SYMBOL(complete_and_exit);
886
887SYSCALL_DEFINE1(exit, int, error_code)
888{
889 do_exit((error_code&0xff)<<8);
890}
891
892/*
893 * Take down every thread in the group. This is called by fatal signals
894 * as well as by sys_exit_group (below).
895 */
896void
897do_group_exit(int exit_code)
898{
899 struct signal_struct *sig = current->signal;
900
901 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
902
903 if (signal_group_exit(sig))
904 exit_code = sig->group_exit_code;
905 else if (!thread_group_empty(current)) {
906 struct sighand_struct *const sighand = current->sighand;
907 spin_lock_irq(&sighand->siglock);
908 if (signal_group_exit(sig))
909 /* Another thread got here before we took the lock. */
910 exit_code = sig->group_exit_code;
911 else {
912 sig->group_exit_code = exit_code;
913 sig->flags = SIGNAL_GROUP_EXIT;
914 zap_other_threads(current);
915 }
916 spin_unlock_irq(&sighand->siglock);
917 }
918
919 do_exit(exit_code);
920 /* NOTREACHED */
921}
922
923/*
924 * this kills every thread in the thread group. Note that any externally
925 * wait4()-ing process will get the correct exit code - even if this
926 * thread is not the thread group leader.
927 */
928SYSCALL_DEFINE1(exit_group, int, error_code)
929{
930 do_group_exit((error_code & 0xff) << 8);
931 /* NOTREACHED */
932 return 0;
933}
934
935struct wait_opts {
936 enum pid_type wo_type;
937 int wo_flags;
938 struct pid *wo_pid;
939
940 struct siginfo __user *wo_info;
941 int __user *wo_stat;
942 struct rusage __user *wo_rusage;
943
944 wait_queue_t child_wait;
945 int notask_error;
946};
947
948static inline
949struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
950{
951 if (type != PIDTYPE_PID)
952 task = task->group_leader;
953 return task->pids[type].pid;
954}
955
956static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
957{
958 return wo->wo_type == PIDTYPE_MAX ||
959 task_pid_type(p, wo->wo_type) == wo->wo_pid;
960}
961
962static int eligible_child(struct wait_opts *wo, struct task_struct *p)
963{
964 if (!eligible_pid(wo, p))
965 return 0;
966 /* Wait for all children (clone and not) if __WALL is set;
967 * otherwise, wait for clone children *only* if __WCLONE is
968 * set; otherwise, wait for non-clone children *only*. (Note:
969 * A "clone" child here is one that reports to its parent
970 * using a signal other than SIGCHLD.) */
971 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
972 && !(wo->wo_flags & __WALL))
973 return 0;
974
975 return 1;
976}
977
978static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
979 pid_t pid, uid_t uid, int why, int status)
980{
981 struct siginfo __user *infop;
982 int retval = wo->wo_rusage
983 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
984
985 put_task_struct(p);
986 infop = wo->wo_info;
987 if (infop) {
988 if (!retval)
989 retval = put_user(SIGCHLD, &infop->si_signo);
990 if (!retval)
991 retval = put_user(0, &infop->si_errno);
992 if (!retval)
993 retval = put_user((short)why, &infop->si_code);
994 if (!retval)
995 retval = put_user(pid, &infop->si_pid);
996 if (!retval)
997 retval = put_user(uid, &infop->si_uid);
998 if (!retval)
999 retval = put_user(status, &infop->si_status);
1000 }
1001 if (!retval)
1002 retval = pid;
1003 return retval;
1004}
1005
1006/*
1007 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1008 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1009 * the lock and this task is uninteresting. If we return nonzero, we have
1010 * released the lock and the system call should return.
1011 */
1012static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1013{
1014 unsigned long state;
1015 int retval, status, traced;
1016 pid_t pid = task_pid_vnr(p);
1017 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1018 struct siginfo __user *infop;
1019
1020 if (!likely(wo->wo_flags & WEXITED))
1021 return 0;
1022
1023 if (unlikely(wo->wo_flags & WNOWAIT)) {
1024 int exit_code = p->exit_code;
1025 int why;
1026
1027 get_task_struct(p);
1028 read_unlock(&tasklist_lock);
1029 if ((exit_code & 0x7f) == 0) {
1030 why = CLD_EXITED;
1031 status = exit_code >> 8;
1032 } else {
1033 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1034 status = exit_code & 0x7f;
1035 }
1036 return wait_noreap_copyout(wo, p, pid, uid, why, status);
1037 }
1038
1039 traced = ptrace_reparented(p);
1040 /*
1041 * Move the task's state to DEAD/TRACE, only one thread can do this.
1042 */
1043 state = traced && thread_group_leader(p) ? EXIT_TRACE : EXIT_DEAD;
1044 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1045 return 0;
1046 /*
1047 * It can be ptraced but not reparented, check
1048 * thread_group_leader() to filter out sub-threads.
1049 */
1050 if (likely(!traced) && thread_group_leader(p)) {
1051 struct signal_struct *psig;
1052 struct signal_struct *sig;
1053 unsigned long maxrss;
1054 cputime_t tgutime, tgstime;
1055
1056 /*
1057 * The resource counters for the group leader are in its
1058 * own task_struct. Those for dead threads in the group
1059 * are in its signal_struct, as are those for the child
1060 * processes it has previously reaped. All these
1061 * accumulate in the parent's signal_struct c* fields.
1062 *
1063 * We don't bother to take a lock here to protect these
1064 * p->signal fields, because they are only touched by
1065 * __exit_signal, which runs with tasklist_lock
1066 * write-locked anyway, and so is excluded here. We do
1067 * need to protect the access to parent->signal fields,
1068 * as other threads in the parent group can be right
1069 * here reaping other children at the same time.
1070 *
1071 * We use thread_group_cputime_adjusted() to get times for the thread
1072 * group, which consolidates times for all threads in the
1073 * group including the group leader.
1074 */
1075 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1076 spin_lock_irq(&p->real_parent->sighand->siglock);
1077 psig = p->real_parent->signal;
1078 sig = p->signal;
1079 psig->cutime += tgutime + sig->cutime;
1080 psig->cstime += tgstime + sig->cstime;
1081 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1082 psig->cmin_flt +=
1083 p->min_flt + sig->min_flt + sig->cmin_flt;
1084 psig->cmaj_flt +=
1085 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1086 psig->cnvcsw +=
1087 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1088 psig->cnivcsw +=
1089 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1090 psig->cinblock +=
1091 task_io_get_inblock(p) +
1092 sig->inblock + sig->cinblock;
1093 psig->coublock +=
1094 task_io_get_oublock(p) +
1095 sig->oublock + sig->coublock;
1096 maxrss = max(sig->maxrss, sig->cmaxrss);
1097 if (psig->cmaxrss < maxrss)
1098 psig->cmaxrss = maxrss;
1099 task_io_accounting_add(&psig->ioac, &p->ioac);
1100 task_io_accounting_add(&psig->ioac, &sig->ioac);
1101 spin_unlock_irq(&p->real_parent->sighand->siglock);
1102 }
1103
1104 /*
1105 * Now we are sure this task is interesting, and no other
1106 * thread can reap it because we its state == DEAD/TRACE.
1107 */
1108 read_unlock(&tasklist_lock);
1109
1110 retval = wo->wo_rusage
1111 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1112 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1113 ? p->signal->group_exit_code : p->exit_code;
1114 if (!retval && wo->wo_stat)
1115 retval = put_user(status, wo->wo_stat);
1116
1117 infop = wo->wo_info;
1118 if (!retval && infop)
1119 retval = put_user(SIGCHLD, &infop->si_signo);
1120 if (!retval && infop)
1121 retval = put_user(0, &infop->si_errno);
1122 if (!retval && infop) {
1123 int why;
1124
1125 if ((status & 0x7f) == 0) {
1126 why = CLD_EXITED;
1127 status >>= 8;
1128 } else {
1129 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1130 status &= 0x7f;
1131 }
1132 retval = put_user((short)why, &infop->si_code);
1133 if (!retval)
1134 retval = put_user(status, &infop->si_status);
1135 }
1136 if (!retval && infop)
1137 retval = put_user(pid, &infop->si_pid);
1138 if (!retval && infop)
1139 retval = put_user(uid, &infop->si_uid);
1140 if (!retval)
1141 retval = pid;
1142
1143 if (state == EXIT_TRACE) {
1144 write_lock_irq(&tasklist_lock);
1145 /* We dropped tasklist, ptracer could die and untrace */
1146 ptrace_unlink(p);
1147
1148 /* If parent wants a zombie, don't release it now */
1149 state = EXIT_ZOMBIE;
1150 if (do_notify_parent(p, p->exit_signal))
1151 state = EXIT_DEAD;
1152 p->exit_state = state;
1153 write_unlock_irq(&tasklist_lock);
1154 }
1155 if (state == EXIT_DEAD)
1156 release_task(p);
1157
1158 return retval;
1159}
1160
1161static int *task_stopped_code(struct task_struct *p, bool ptrace)
1162{
1163 if (ptrace) {
1164 if (task_is_stopped_or_traced(p) &&
1165 !(p->jobctl & JOBCTL_LISTENING))
1166 return &p->exit_code;
1167 } else {
1168 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1169 return &p->signal->group_exit_code;
1170 }
1171 return NULL;
1172}
1173
1174/**
1175 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1176 * @wo: wait options
1177 * @ptrace: is the wait for ptrace
1178 * @p: task to wait for
1179 *
1180 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1181 *
1182 * CONTEXT:
1183 * read_lock(&tasklist_lock), which is released if return value is
1184 * non-zero. Also, grabs and releases @p->sighand->siglock.
1185 *
1186 * RETURNS:
1187 * 0 if wait condition didn't exist and search for other wait conditions
1188 * should continue. Non-zero return, -errno on failure and @p's pid on
1189 * success, implies that tasklist_lock is released and wait condition
1190 * search should terminate.
1191 */
1192static int wait_task_stopped(struct wait_opts *wo,
1193 int ptrace, struct task_struct *p)
1194{
1195 struct siginfo __user *infop;
1196 int retval, exit_code, *p_code, why;
1197 uid_t uid = 0; /* unneeded, required by compiler */
1198 pid_t pid;
1199
1200 /*
1201 * Traditionally we see ptrace'd stopped tasks regardless of options.
1202 */
1203 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1204 return 0;
1205
1206 if (!task_stopped_code(p, ptrace))
1207 return 0;
1208
1209 exit_code = 0;
1210 spin_lock_irq(&p->sighand->siglock);
1211
1212 p_code = task_stopped_code(p, ptrace);
1213 if (unlikely(!p_code))
1214 goto unlock_sig;
1215
1216 exit_code = *p_code;
1217 if (!exit_code)
1218 goto unlock_sig;
1219
1220 if (!unlikely(wo->wo_flags & WNOWAIT))
1221 *p_code = 0;
1222
1223 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1224unlock_sig:
1225 spin_unlock_irq(&p->sighand->siglock);
1226 if (!exit_code)
1227 return 0;
1228
1229 /*
1230 * Now we are pretty sure this task is interesting.
1231 * Make sure it doesn't get reaped out from under us while we
1232 * give up the lock and then examine it below. We don't want to
1233 * keep holding onto the tasklist_lock while we call getrusage and
1234 * possibly take page faults for user memory.
1235 */
1236 get_task_struct(p);
1237 pid = task_pid_vnr(p);
1238 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1239 read_unlock(&tasklist_lock);
1240
1241 if (unlikely(wo->wo_flags & WNOWAIT))
1242 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
1243
1244 retval = wo->wo_rusage
1245 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1246 if (!retval && wo->wo_stat)
1247 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
1248
1249 infop = wo->wo_info;
1250 if (!retval && infop)
1251 retval = put_user(SIGCHLD, &infop->si_signo);
1252 if (!retval && infop)
1253 retval = put_user(0, &infop->si_errno);
1254 if (!retval && infop)
1255 retval = put_user((short)why, &infop->si_code);
1256 if (!retval && infop)
1257 retval = put_user(exit_code, &infop->si_status);
1258 if (!retval && infop)
1259 retval = put_user(pid, &infop->si_pid);
1260 if (!retval && infop)
1261 retval = put_user(uid, &infop->si_uid);
1262 if (!retval)
1263 retval = pid;
1264 put_task_struct(p);
1265
1266 BUG_ON(!retval);
1267 return retval;
1268}
1269
1270/*
1271 * Handle do_wait work for one task in a live, non-stopped state.
1272 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1273 * the lock and this task is uninteresting. If we return nonzero, we have
1274 * released the lock and the system call should return.
1275 */
1276static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1277{
1278 int retval;
1279 pid_t pid;
1280 uid_t uid;
1281
1282 if (!unlikely(wo->wo_flags & WCONTINUED))
1283 return 0;
1284
1285 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1286 return 0;
1287
1288 spin_lock_irq(&p->sighand->siglock);
1289 /* Re-check with the lock held. */
1290 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1291 spin_unlock_irq(&p->sighand->siglock);
1292 return 0;
1293 }
1294 if (!unlikely(wo->wo_flags & WNOWAIT))
1295 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1296 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1297 spin_unlock_irq(&p->sighand->siglock);
1298
1299 pid = task_pid_vnr(p);
1300 get_task_struct(p);
1301 read_unlock(&tasklist_lock);
1302
1303 if (!wo->wo_info) {
1304 retval = wo->wo_rusage
1305 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1306 put_task_struct(p);
1307 if (!retval && wo->wo_stat)
1308 retval = put_user(0xffff, wo->wo_stat);
1309 if (!retval)
1310 retval = pid;
1311 } else {
1312 retval = wait_noreap_copyout(wo, p, pid, uid,
1313 CLD_CONTINUED, SIGCONT);
1314 BUG_ON(retval == 0);
1315 }
1316
1317 return retval;
1318}
1319
1320/*
1321 * Consider @p for a wait by @parent.
1322 *
1323 * -ECHILD should be in ->notask_error before the first call.
1324 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1325 * Returns zero if the search for a child should continue;
1326 * then ->notask_error is 0 if @p is an eligible child,
1327 * or another error from security_task_wait(), or still -ECHILD.
1328 */
1329static int wait_consider_task(struct wait_opts *wo, int ptrace,
1330 struct task_struct *p)
1331{
1332 int ret;
1333
1334 if (unlikely(p->exit_state == EXIT_DEAD))
1335 return 0;
1336
1337 ret = eligible_child(wo, p);
1338 if (!ret)
1339 return ret;
1340
1341 ret = security_task_wait(p);
1342 if (unlikely(ret < 0)) {
1343 /*
1344 * If we have not yet seen any eligible child,
1345 * then let this error code replace -ECHILD.
1346 * A permission error will give the user a clue
1347 * to look for security policy problems, rather
1348 * than for mysterious wait bugs.
1349 */
1350 if (wo->notask_error)
1351 wo->notask_error = ret;
1352 return 0;
1353 }
1354
1355 if (unlikely(p->exit_state == EXIT_TRACE)) {
1356 /*
1357 * ptrace == 0 means we are the natural parent. In this case
1358 * we should clear notask_error, debugger will notify us.
1359 */
1360 if (likely(!ptrace))
1361 wo->notask_error = 0;
1362 return 0;
1363 }
1364
1365 if (likely(!ptrace) && unlikely(p->ptrace)) {
1366 /*
1367 * If it is traced by its real parent's group, just pretend
1368 * the caller is ptrace_do_wait() and reap this child if it
1369 * is zombie.
1370 *
1371 * This also hides group stop state from real parent; otherwise
1372 * a single stop can be reported twice as group and ptrace stop.
1373 * If a ptracer wants to distinguish these two events for its
1374 * own children it should create a separate process which takes
1375 * the role of real parent.
1376 */
1377 if (!ptrace_reparented(p))
1378 ptrace = 1;
1379 }
1380
1381 /* slay zombie? */
1382 if (p->exit_state == EXIT_ZOMBIE) {
1383 /* we don't reap group leaders with subthreads */
1384 if (!delay_group_leader(p)) {
1385 /*
1386 * A zombie ptracee is only visible to its ptracer.
1387 * Notification and reaping will be cascaded to the
1388 * real parent when the ptracer detaches.
1389 */
1390 if (unlikely(ptrace) || likely(!p->ptrace))
1391 return wait_task_zombie(wo, p);
1392 }
1393
1394 /*
1395 * Allow access to stopped/continued state via zombie by
1396 * falling through. Clearing of notask_error is complex.
1397 *
1398 * When !@ptrace:
1399 *
1400 * If WEXITED is set, notask_error should naturally be
1401 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1402 * so, if there are live subthreads, there are events to
1403 * wait for. If all subthreads are dead, it's still safe
1404 * to clear - this function will be called again in finite
1405 * amount time once all the subthreads are released and
1406 * will then return without clearing.
1407 *
1408 * When @ptrace:
1409 *
1410 * Stopped state is per-task and thus can't change once the
1411 * target task dies. Only continued and exited can happen.
1412 * Clear notask_error if WCONTINUED | WEXITED.
1413 */
1414 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1415 wo->notask_error = 0;
1416 } else {
1417 /*
1418 * @p is alive and it's gonna stop, continue or exit, so
1419 * there always is something to wait for.
1420 */
1421 wo->notask_error = 0;
1422 }
1423
1424 /*
1425 * Wait for stopped. Depending on @ptrace, different stopped state
1426 * is used and the two don't interact with each other.
1427 */
1428 ret = wait_task_stopped(wo, ptrace, p);
1429 if (ret)
1430 return ret;
1431
1432 /*
1433 * Wait for continued. There's only one continued state and the
1434 * ptracer can consume it which can confuse the real parent. Don't
1435 * use WCONTINUED from ptracer. You don't need or want it.
1436 */
1437 return wait_task_continued(wo, p);
1438}
1439
1440/*
1441 * Do the work of do_wait() for one thread in the group, @tsk.
1442 *
1443 * -ECHILD should be in ->notask_error before the first call.
1444 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1445 * Returns zero if the search for a child should continue; then
1446 * ->notask_error is 0 if there were any eligible children,
1447 * or another error from security_task_wait(), or still -ECHILD.
1448 */
1449static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1450{
1451 struct task_struct *p;
1452
1453 list_for_each_entry(p, &tsk->children, sibling) {
1454 int ret = wait_consider_task(wo, 0, p);
1455 if (ret)
1456 return ret;
1457 }
1458
1459 return 0;
1460}
1461
1462static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1463{
1464 struct task_struct *p;
1465
1466 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1467 int ret = wait_consider_task(wo, 1, p);
1468 if (ret)
1469 return ret;
1470 }
1471
1472 return 0;
1473}
1474
1475static int child_wait_callback(wait_queue_t *wait, unsigned mode,
1476 int sync, void *key)
1477{
1478 struct wait_opts *wo = container_of(wait, struct wait_opts,
1479 child_wait);
1480 struct task_struct *p = key;
1481
1482 if (!eligible_pid(wo, p))
1483 return 0;
1484
1485 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1486 return 0;
1487
1488 return default_wake_function(wait, mode, sync, key);
1489}
1490
1491void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1492{
1493 __wake_up_sync_key(&parent->signal->wait_chldexit,
1494 TASK_INTERRUPTIBLE, 1, p);
1495}
1496
1497static long do_wait(struct wait_opts *wo)
1498{
1499 struct task_struct *tsk;
1500 int retval;
1501
1502 trace_sched_process_wait(wo->wo_pid);
1503
1504 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1505 wo->child_wait.private = current;
1506 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1507repeat:
1508 /*
1509 * If there is nothing that can match our critiera just get out.
1510 * We will clear ->notask_error to zero if we see any child that
1511 * might later match our criteria, even if we are not able to reap
1512 * it yet.
1513 */
1514 wo->notask_error = -ECHILD;
1515 if ((wo->wo_type < PIDTYPE_MAX) &&
1516 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1517 goto notask;
1518
1519 set_current_state(TASK_INTERRUPTIBLE);
1520 read_lock(&tasklist_lock);
1521 tsk = current;
1522 do {
1523 retval = do_wait_thread(wo, tsk);
1524 if (retval)
1525 goto end;
1526
1527 retval = ptrace_do_wait(wo, tsk);
1528 if (retval)
1529 goto end;
1530
1531 if (wo->wo_flags & __WNOTHREAD)
1532 break;
1533 } while_each_thread(current, tsk);
1534 read_unlock(&tasklist_lock);
1535
1536notask:
1537 retval = wo->notask_error;
1538 if (!retval && !(wo->wo_flags & WNOHANG)) {
1539 retval = -ERESTARTSYS;
1540 if (!signal_pending(current)) {
1541 schedule();
1542 goto repeat;
1543 }
1544 }
1545end:
1546 __set_current_state(TASK_RUNNING);
1547 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1548 return retval;
1549}
1550
1551SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1552 infop, int, options, struct rusage __user *, ru)
1553{
1554 struct wait_opts wo;
1555 struct pid *pid = NULL;
1556 enum pid_type type;
1557 long ret;
1558
1559 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1560 return -EINVAL;
1561 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1562 return -EINVAL;
1563
1564 switch (which) {
1565 case P_ALL:
1566 type = PIDTYPE_MAX;
1567 break;
1568 case P_PID:
1569 type = PIDTYPE_PID;
1570 if (upid <= 0)
1571 return -EINVAL;
1572 break;
1573 case P_PGID:
1574 type = PIDTYPE_PGID;
1575 if (upid <= 0)
1576 return -EINVAL;
1577 break;
1578 default:
1579 return -EINVAL;
1580 }
1581
1582 if (type < PIDTYPE_MAX)
1583 pid = find_get_pid(upid);
1584
1585 wo.wo_type = type;
1586 wo.wo_pid = pid;
1587 wo.wo_flags = options;
1588 wo.wo_info = infop;
1589 wo.wo_stat = NULL;
1590 wo.wo_rusage = ru;
1591 ret = do_wait(&wo);
1592
1593 if (ret > 0) {
1594 ret = 0;
1595 } else if (infop) {
1596 /*
1597 * For a WNOHANG return, clear out all the fields
1598 * we would set so the user can easily tell the
1599 * difference.
1600 */
1601 if (!ret)
1602 ret = put_user(0, &infop->si_signo);
1603 if (!ret)
1604 ret = put_user(0, &infop->si_errno);
1605 if (!ret)
1606 ret = put_user(0, &infop->si_code);
1607 if (!ret)
1608 ret = put_user(0, &infop->si_pid);
1609 if (!ret)
1610 ret = put_user(0, &infop->si_uid);
1611 if (!ret)
1612 ret = put_user(0, &infop->si_status);
1613 }
1614
1615 put_pid(pid);
1616 return ret;
1617}
1618
1619SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1620 int, options, struct rusage __user *, ru)
1621{
1622 struct wait_opts wo;
1623 struct pid *pid = NULL;
1624 enum pid_type type;
1625 long ret;
1626
1627 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1628 __WNOTHREAD|__WCLONE|__WALL))
1629 return -EINVAL;
1630
1631 if (upid == -1)
1632 type = PIDTYPE_MAX;
1633 else if (upid < 0) {
1634 type = PIDTYPE_PGID;
1635 pid = find_get_pid(-upid);
1636 } else if (upid == 0) {
1637 type = PIDTYPE_PGID;
1638 pid = get_task_pid(current, PIDTYPE_PGID);
1639 } else /* upid > 0 */ {
1640 type = PIDTYPE_PID;
1641 pid = find_get_pid(upid);
1642 }
1643
1644 wo.wo_type = type;
1645 wo.wo_pid = pid;
1646 wo.wo_flags = options | WEXITED;
1647 wo.wo_info = NULL;
1648 wo.wo_stat = stat_addr;
1649 wo.wo_rusage = ru;
1650 ret = do_wait(&wo);
1651 put_pid(pid);
1652
1653 return ret;
1654}
1655
1656#ifdef __ARCH_WANT_SYS_WAITPID
1657
1658/*
1659 * sys_waitpid() remains for compatibility. waitpid() should be
1660 * implemented by calling sys_wait4() from libc.a.
1661 */
1662SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1663{
1664 return sys_wait4(pid, stat_addr, options, NULL);
1665}
1666
1667#endif
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/exit.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8#include <linux/mm.h>
9#include <linux/slab.h>
10#include <linux/sched/autogroup.h>
11#include <linux/sched/mm.h>
12#include <linux/sched/stat.h>
13#include <linux/sched/task.h>
14#include <linux/sched/task_stack.h>
15#include <linux/sched/cputime.h>
16#include <linux/interrupt.h>
17#include <linux/module.h>
18#include <linux/capability.h>
19#include <linux/completion.h>
20#include <linux/personality.h>
21#include <linux/tty.h>
22#include <linux/iocontext.h>
23#include <linux/key.h>
24#include <linux/cpu.h>
25#include <linux/acct.h>
26#include <linux/tsacct_kern.h>
27#include <linux/file.h>
28#include <linux/fdtable.h>
29#include <linux/freezer.h>
30#include <linux/binfmts.h>
31#include <linux/nsproxy.h>
32#include <linux/pid_namespace.h>
33#include <linux/ptrace.h>
34#include <linux/profile.h>
35#include <linux/mount.h>
36#include <linux/proc_fs.h>
37#include <linux/kthread.h>
38#include <linux/mempolicy.h>
39#include <linux/taskstats_kern.h>
40#include <linux/delayacct.h>
41#include <linux/cgroup.h>
42#include <linux/syscalls.h>
43#include <linux/signal.h>
44#include <linux/posix-timers.h>
45#include <linux/cn_proc.h>
46#include <linux/mutex.h>
47#include <linux/futex.h>
48#include <linux/pipe_fs_i.h>
49#include <linux/audit.h> /* for audit_free() */
50#include <linux/resource.h>
51#include <linux/blkdev.h>
52#include <linux/task_io_accounting_ops.h>
53#include <linux/tracehook.h>
54#include <linux/fs_struct.h>
55#include <linux/init_task.h>
56#include <linux/perf_event.h>
57#include <trace/events/sched.h>
58#include <linux/hw_breakpoint.h>
59#include <linux/oom.h>
60#include <linux/writeback.h>
61#include <linux/shm.h>
62#include <linux/kcov.h>
63#include <linux/random.h>
64#include <linux/rcuwait.h>
65#include <linux/compat.h>
66
67#include <linux/uaccess.h>
68#include <asm/unistd.h>
69#include <asm/pgtable.h>
70#include <asm/mmu_context.h>
71
72static void __unhash_process(struct task_struct *p, bool group_dead)
73{
74 nr_threads--;
75 detach_pid(p, PIDTYPE_PID);
76 if (group_dead) {
77 detach_pid(p, PIDTYPE_TGID);
78 detach_pid(p, PIDTYPE_PGID);
79 detach_pid(p, PIDTYPE_SID);
80
81 list_del_rcu(&p->tasks);
82 list_del_init(&p->sibling);
83 __this_cpu_dec(process_counts);
84 }
85 list_del_rcu(&p->thread_group);
86 list_del_rcu(&p->thread_node);
87}
88
89/*
90 * This function expects the tasklist_lock write-locked.
91 */
92static void __exit_signal(struct task_struct *tsk)
93{
94 struct signal_struct *sig = tsk->signal;
95 bool group_dead = thread_group_leader(tsk);
96 struct sighand_struct *sighand;
97 struct tty_struct *uninitialized_var(tty);
98 u64 utime, stime;
99
100 sighand = rcu_dereference_check(tsk->sighand,
101 lockdep_tasklist_lock_is_held());
102 spin_lock(&sighand->siglock);
103
104#ifdef CONFIG_POSIX_TIMERS
105 posix_cpu_timers_exit(tsk);
106 if (group_dead) {
107 posix_cpu_timers_exit_group(tsk);
108 } else {
109 /*
110 * This can only happen if the caller is de_thread().
111 * FIXME: this is the temporary hack, we should teach
112 * posix-cpu-timers to handle this case correctly.
113 */
114 if (unlikely(has_group_leader_pid(tsk)))
115 posix_cpu_timers_exit_group(tsk);
116 }
117#endif
118
119 if (group_dead) {
120 tty = sig->tty;
121 sig->tty = NULL;
122 } else {
123 /*
124 * If there is any task waiting for the group exit
125 * then notify it:
126 */
127 if (sig->notify_count > 0 && !--sig->notify_count)
128 wake_up_process(sig->group_exit_task);
129
130 if (tsk == sig->curr_target)
131 sig->curr_target = next_thread(tsk);
132 }
133
134 add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
135 sizeof(unsigned long long));
136
137 /*
138 * Accumulate here the counters for all threads as they die. We could
139 * skip the group leader because it is the last user of signal_struct,
140 * but we want to avoid the race with thread_group_cputime() which can
141 * see the empty ->thread_head list.
142 */
143 task_cputime(tsk, &utime, &stime);
144 write_seqlock(&sig->stats_lock);
145 sig->utime += utime;
146 sig->stime += stime;
147 sig->gtime += task_gtime(tsk);
148 sig->min_flt += tsk->min_flt;
149 sig->maj_flt += tsk->maj_flt;
150 sig->nvcsw += tsk->nvcsw;
151 sig->nivcsw += tsk->nivcsw;
152 sig->inblock += task_io_get_inblock(tsk);
153 sig->oublock += task_io_get_oublock(tsk);
154 task_io_accounting_add(&sig->ioac, &tsk->ioac);
155 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
156 sig->nr_threads--;
157 __unhash_process(tsk, group_dead);
158 write_sequnlock(&sig->stats_lock);
159
160 /*
161 * Do this under ->siglock, we can race with another thread
162 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
163 */
164 flush_sigqueue(&tsk->pending);
165 tsk->sighand = NULL;
166 spin_unlock(&sighand->siglock);
167
168 __cleanup_sighand(sighand);
169 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
170 if (group_dead) {
171 flush_sigqueue(&sig->shared_pending);
172 tty_kref_put(tty);
173 }
174}
175
176static void delayed_put_task_struct(struct rcu_head *rhp)
177{
178 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
179
180 perf_event_delayed_put(tsk);
181 trace_sched_process_free(tsk);
182 put_task_struct(tsk);
183}
184
185void put_task_struct_rcu_user(struct task_struct *task)
186{
187 if (refcount_dec_and_test(&task->rcu_users))
188 call_rcu(&task->rcu, delayed_put_task_struct);
189}
190
191void release_task(struct task_struct *p)
192{
193 struct task_struct *leader;
194 int zap_leader;
195repeat:
196 /* don't need to get the RCU readlock here - the process is dead and
197 * can't be modifying its own credentials. But shut RCU-lockdep up */
198 rcu_read_lock();
199 atomic_dec(&__task_cred(p)->user->processes);
200 rcu_read_unlock();
201
202 proc_flush_task(p);
203 cgroup_release(p);
204
205 write_lock_irq(&tasklist_lock);
206 ptrace_release_task(p);
207 __exit_signal(p);
208
209 /*
210 * If we are the last non-leader member of the thread
211 * group, and the leader is zombie, then notify the
212 * group leader's parent process. (if it wants notification.)
213 */
214 zap_leader = 0;
215 leader = p->group_leader;
216 if (leader != p && thread_group_empty(leader)
217 && leader->exit_state == EXIT_ZOMBIE) {
218 /*
219 * If we were the last child thread and the leader has
220 * exited already, and the leader's parent ignores SIGCHLD,
221 * then we are the one who should release the leader.
222 */
223 zap_leader = do_notify_parent(leader, leader->exit_signal);
224 if (zap_leader)
225 leader->exit_state = EXIT_DEAD;
226 }
227
228 write_unlock_irq(&tasklist_lock);
229 release_thread(p);
230 put_task_struct_rcu_user(p);
231
232 p = leader;
233 if (unlikely(zap_leader))
234 goto repeat;
235}
236
237void rcuwait_wake_up(struct rcuwait *w)
238{
239 struct task_struct *task;
240
241 rcu_read_lock();
242
243 /*
244 * Order condition vs @task, such that everything prior to the load
245 * of @task is visible. This is the condition as to why the user called
246 * rcuwait_trywake() in the first place. Pairs with set_current_state()
247 * barrier (A) in rcuwait_wait_event().
248 *
249 * WAIT WAKE
250 * [S] tsk = current [S] cond = true
251 * MB (A) MB (B)
252 * [L] cond [L] tsk
253 */
254 smp_mb(); /* (B) */
255
256 task = rcu_dereference(w->task);
257 if (task)
258 wake_up_process(task);
259 rcu_read_unlock();
260}
261
262/*
263 * Determine if a process group is "orphaned", according to the POSIX
264 * definition in 2.2.2.52. Orphaned process groups are not to be affected
265 * by terminal-generated stop signals. Newly orphaned process groups are
266 * to receive a SIGHUP and a SIGCONT.
267 *
268 * "I ask you, have you ever known what it is to be an orphan?"
269 */
270static int will_become_orphaned_pgrp(struct pid *pgrp,
271 struct task_struct *ignored_task)
272{
273 struct task_struct *p;
274
275 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
276 if ((p == ignored_task) ||
277 (p->exit_state && thread_group_empty(p)) ||
278 is_global_init(p->real_parent))
279 continue;
280
281 if (task_pgrp(p->real_parent) != pgrp &&
282 task_session(p->real_parent) == task_session(p))
283 return 0;
284 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
285
286 return 1;
287}
288
289int is_current_pgrp_orphaned(void)
290{
291 int retval;
292
293 read_lock(&tasklist_lock);
294 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
295 read_unlock(&tasklist_lock);
296
297 return retval;
298}
299
300static bool has_stopped_jobs(struct pid *pgrp)
301{
302 struct task_struct *p;
303
304 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
305 if (p->signal->flags & SIGNAL_STOP_STOPPED)
306 return true;
307 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
308
309 return false;
310}
311
312/*
313 * Check to see if any process groups have become orphaned as
314 * a result of our exiting, and if they have any stopped jobs,
315 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
316 */
317static void
318kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
319{
320 struct pid *pgrp = task_pgrp(tsk);
321 struct task_struct *ignored_task = tsk;
322
323 if (!parent)
324 /* exit: our father is in a different pgrp than
325 * we are and we were the only connection outside.
326 */
327 parent = tsk->real_parent;
328 else
329 /* reparent: our child is in a different pgrp than
330 * we are, and it was the only connection outside.
331 */
332 ignored_task = NULL;
333
334 if (task_pgrp(parent) != pgrp &&
335 task_session(parent) == task_session(tsk) &&
336 will_become_orphaned_pgrp(pgrp, ignored_task) &&
337 has_stopped_jobs(pgrp)) {
338 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
339 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
340 }
341}
342
343#ifdef CONFIG_MEMCG
344/*
345 * A task is exiting. If it owned this mm, find a new owner for the mm.
346 */
347void mm_update_next_owner(struct mm_struct *mm)
348{
349 struct task_struct *c, *g, *p = current;
350
351retry:
352 /*
353 * If the exiting or execing task is not the owner, it's
354 * someone else's problem.
355 */
356 if (mm->owner != p)
357 return;
358 /*
359 * The current owner is exiting/execing and there are no other
360 * candidates. Do not leave the mm pointing to a possibly
361 * freed task structure.
362 */
363 if (atomic_read(&mm->mm_users) <= 1) {
364 WRITE_ONCE(mm->owner, NULL);
365 return;
366 }
367
368 read_lock(&tasklist_lock);
369 /*
370 * Search in the children
371 */
372 list_for_each_entry(c, &p->children, sibling) {
373 if (c->mm == mm)
374 goto assign_new_owner;
375 }
376
377 /*
378 * Search in the siblings
379 */
380 list_for_each_entry(c, &p->real_parent->children, sibling) {
381 if (c->mm == mm)
382 goto assign_new_owner;
383 }
384
385 /*
386 * Search through everything else, we should not get here often.
387 */
388 for_each_process(g) {
389 if (g->flags & PF_KTHREAD)
390 continue;
391 for_each_thread(g, c) {
392 if (c->mm == mm)
393 goto assign_new_owner;
394 if (c->mm)
395 break;
396 }
397 }
398 read_unlock(&tasklist_lock);
399 /*
400 * We found no owner yet mm_users > 1: this implies that we are
401 * most likely racing with swapoff (try_to_unuse()) or /proc or
402 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
403 */
404 WRITE_ONCE(mm->owner, NULL);
405 return;
406
407assign_new_owner:
408 BUG_ON(c == p);
409 get_task_struct(c);
410 /*
411 * The task_lock protects c->mm from changing.
412 * We always want mm->owner->mm == mm
413 */
414 task_lock(c);
415 /*
416 * Delay read_unlock() till we have the task_lock()
417 * to ensure that c does not slip away underneath us
418 */
419 read_unlock(&tasklist_lock);
420 if (c->mm != mm) {
421 task_unlock(c);
422 put_task_struct(c);
423 goto retry;
424 }
425 WRITE_ONCE(mm->owner, c);
426 task_unlock(c);
427 put_task_struct(c);
428}
429#endif /* CONFIG_MEMCG */
430
431/*
432 * Turn us into a lazy TLB process if we
433 * aren't already..
434 */
435static void exit_mm(void)
436{
437 struct mm_struct *mm = current->mm;
438 struct core_state *core_state;
439
440 mm_release(current, mm);
441 if (!mm)
442 return;
443 sync_mm_rss(mm);
444 /*
445 * Serialize with any possible pending coredump.
446 * We must hold mmap_sem around checking core_state
447 * and clearing tsk->mm. The core-inducing thread
448 * will increment ->nr_threads for each thread in the
449 * group with ->mm != NULL.
450 */
451 down_read(&mm->mmap_sem);
452 core_state = mm->core_state;
453 if (core_state) {
454 struct core_thread self;
455
456 up_read(&mm->mmap_sem);
457
458 self.task = current;
459 self.next = xchg(&core_state->dumper.next, &self);
460 /*
461 * Implies mb(), the result of xchg() must be visible
462 * to core_state->dumper.
463 */
464 if (atomic_dec_and_test(&core_state->nr_threads))
465 complete(&core_state->startup);
466
467 for (;;) {
468 set_current_state(TASK_UNINTERRUPTIBLE);
469 if (!self.task) /* see coredump_finish() */
470 break;
471 freezable_schedule();
472 }
473 __set_current_state(TASK_RUNNING);
474 down_read(&mm->mmap_sem);
475 }
476 mmgrab(mm);
477 BUG_ON(mm != current->active_mm);
478 /* more a memory barrier than a real lock */
479 task_lock(current);
480 current->mm = NULL;
481 up_read(&mm->mmap_sem);
482 enter_lazy_tlb(mm, current);
483 task_unlock(current);
484 mm_update_next_owner(mm);
485 mmput(mm);
486 if (test_thread_flag(TIF_MEMDIE))
487 exit_oom_victim();
488}
489
490static struct task_struct *find_alive_thread(struct task_struct *p)
491{
492 struct task_struct *t;
493
494 for_each_thread(p, t) {
495 if (!(t->flags & PF_EXITING))
496 return t;
497 }
498 return NULL;
499}
500
501static struct task_struct *find_child_reaper(struct task_struct *father,
502 struct list_head *dead)
503 __releases(&tasklist_lock)
504 __acquires(&tasklist_lock)
505{
506 struct pid_namespace *pid_ns = task_active_pid_ns(father);
507 struct task_struct *reaper = pid_ns->child_reaper;
508 struct task_struct *p, *n;
509
510 if (likely(reaper != father))
511 return reaper;
512
513 reaper = find_alive_thread(father);
514 if (reaper) {
515 pid_ns->child_reaper = reaper;
516 return reaper;
517 }
518
519 write_unlock_irq(&tasklist_lock);
520 if (unlikely(pid_ns == &init_pid_ns)) {
521 panic("Attempted to kill init! exitcode=0x%08x\n",
522 father->signal->group_exit_code ?: father->exit_code);
523 }
524
525 list_for_each_entry_safe(p, n, dead, ptrace_entry) {
526 list_del_init(&p->ptrace_entry);
527 release_task(p);
528 }
529
530 zap_pid_ns_processes(pid_ns);
531 write_lock_irq(&tasklist_lock);
532
533 return father;
534}
535
536/*
537 * When we die, we re-parent all our children, and try to:
538 * 1. give them to another thread in our thread group, if such a member exists
539 * 2. give it to the first ancestor process which prctl'd itself as a
540 * child_subreaper for its children (like a service manager)
541 * 3. give it to the init process (PID 1) in our pid namespace
542 */
543static struct task_struct *find_new_reaper(struct task_struct *father,
544 struct task_struct *child_reaper)
545{
546 struct task_struct *thread, *reaper;
547
548 thread = find_alive_thread(father);
549 if (thread)
550 return thread;
551
552 if (father->signal->has_child_subreaper) {
553 unsigned int ns_level = task_pid(father)->level;
554 /*
555 * Find the first ->is_child_subreaper ancestor in our pid_ns.
556 * We can't check reaper != child_reaper to ensure we do not
557 * cross the namespaces, the exiting parent could be injected
558 * by setns() + fork().
559 * We check pid->level, this is slightly more efficient than
560 * task_active_pid_ns(reaper) != task_active_pid_ns(father).
561 */
562 for (reaper = father->real_parent;
563 task_pid(reaper)->level == ns_level;
564 reaper = reaper->real_parent) {
565 if (reaper == &init_task)
566 break;
567 if (!reaper->signal->is_child_subreaper)
568 continue;
569 thread = find_alive_thread(reaper);
570 if (thread)
571 return thread;
572 }
573 }
574
575 return child_reaper;
576}
577
578/*
579* Any that need to be release_task'd are put on the @dead list.
580 */
581static void reparent_leader(struct task_struct *father, struct task_struct *p,
582 struct list_head *dead)
583{
584 if (unlikely(p->exit_state == EXIT_DEAD))
585 return;
586
587 /* We don't want people slaying init. */
588 p->exit_signal = SIGCHLD;
589
590 /* If it has exited notify the new parent about this child's death. */
591 if (!p->ptrace &&
592 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
593 if (do_notify_parent(p, p->exit_signal)) {
594 p->exit_state = EXIT_DEAD;
595 list_add(&p->ptrace_entry, dead);
596 }
597 }
598
599 kill_orphaned_pgrp(p, father);
600}
601
602/*
603 * This does two things:
604 *
605 * A. Make init inherit all the child processes
606 * B. Check to see if any process groups have become orphaned
607 * as a result of our exiting, and if they have any stopped
608 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
609 */
610static void forget_original_parent(struct task_struct *father,
611 struct list_head *dead)
612{
613 struct task_struct *p, *t, *reaper;
614
615 if (unlikely(!list_empty(&father->ptraced)))
616 exit_ptrace(father, dead);
617
618 /* Can drop and reacquire tasklist_lock */
619 reaper = find_child_reaper(father, dead);
620 if (list_empty(&father->children))
621 return;
622
623 reaper = find_new_reaper(father, reaper);
624 list_for_each_entry(p, &father->children, sibling) {
625 for_each_thread(p, t) {
626 t->real_parent = reaper;
627 BUG_ON((!t->ptrace) != (t->parent == father));
628 if (likely(!t->ptrace))
629 t->parent = t->real_parent;
630 if (t->pdeath_signal)
631 group_send_sig_info(t->pdeath_signal,
632 SEND_SIG_NOINFO, t,
633 PIDTYPE_TGID);
634 }
635 /*
636 * If this is a threaded reparent there is no need to
637 * notify anyone anything has happened.
638 */
639 if (!same_thread_group(reaper, father))
640 reparent_leader(father, p, dead);
641 }
642 list_splice_tail_init(&father->children, &reaper->children);
643}
644
645/*
646 * Send signals to all our closest relatives so that they know
647 * to properly mourn us..
648 */
649static void exit_notify(struct task_struct *tsk, int group_dead)
650{
651 bool autoreap;
652 struct task_struct *p, *n;
653 LIST_HEAD(dead);
654
655 write_lock_irq(&tasklist_lock);
656 forget_original_parent(tsk, &dead);
657
658 if (group_dead)
659 kill_orphaned_pgrp(tsk->group_leader, NULL);
660
661 tsk->exit_state = EXIT_ZOMBIE;
662 if (unlikely(tsk->ptrace)) {
663 int sig = thread_group_leader(tsk) &&
664 thread_group_empty(tsk) &&
665 !ptrace_reparented(tsk) ?
666 tsk->exit_signal : SIGCHLD;
667 autoreap = do_notify_parent(tsk, sig);
668 } else if (thread_group_leader(tsk)) {
669 autoreap = thread_group_empty(tsk) &&
670 do_notify_parent(tsk, tsk->exit_signal);
671 } else {
672 autoreap = true;
673 }
674
675 if (autoreap) {
676 tsk->exit_state = EXIT_DEAD;
677 list_add(&tsk->ptrace_entry, &dead);
678 }
679
680 /* mt-exec, de_thread() is waiting for group leader */
681 if (unlikely(tsk->signal->notify_count < 0))
682 wake_up_process(tsk->signal->group_exit_task);
683 write_unlock_irq(&tasklist_lock);
684
685 list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
686 list_del_init(&p->ptrace_entry);
687 release_task(p);
688 }
689}
690
691#ifdef CONFIG_DEBUG_STACK_USAGE
692static void check_stack_usage(void)
693{
694 static DEFINE_SPINLOCK(low_water_lock);
695 static int lowest_to_date = THREAD_SIZE;
696 unsigned long free;
697
698 free = stack_not_used(current);
699
700 if (free >= lowest_to_date)
701 return;
702
703 spin_lock(&low_water_lock);
704 if (free < lowest_to_date) {
705 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
706 current->comm, task_pid_nr(current), free);
707 lowest_to_date = free;
708 }
709 spin_unlock(&low_water_lock);
710}
711#else
712static inline void check_stack_usage(void) {}
713#endif
714
715void __noreturn do_exit(long code)
716{
717 struct task_struct *tsk = current;
718 int group_dead;
719
720 profile_task_exit(tsk);
721 kcov_task_exit(tsk);
722
723 WARN_ON(blk_needs_flush_plug(tsk));
724
725 if (unlikely(in_interrupt()))
726 panic("Aiee, killing interrupt handler!");
727 if (unlikely(!tsk->pid))
728 panic("Attempted to kill the idle task!");
729
730 /*
731 * If do_exit is called because this processes oopsed, it's possible
732 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
733 * continuing. Amongst other possible reasons, this is to prevent
734 * mm_release()->clear_child_tid() from writing to a user-controlled
735 * kernel address.
736 */
737 set_fs(USER_DS);
738
739 ptrace_event(PTRACE_EVENT_EXIT, code);
740
741 validate_creds_for_do_exit(tsk);
742
743 /*
744 * We're taking recursive faults here in do_exit. Safest is to just
745 * leave this task alone and wait for reboot.
746 */
747 if (unlikely(tsk->flags & PF_EXITING)) {
748 pr_alert("Fixing recursive fault but reboot is needed!\n");
749 /*
750 * We can do this unlocked here. The futex code uses
751 * this flag just to verify whether the pi state
752 * cleanup has been done or not. In the worst case it
753 * loops once more. We pretend that the cleanup was
754 * done as there is no way to return. Either the
755 * OWNER_DIED bit is set by now or we push the blocked
756 * task into the wait for ever nirwana as well.
757 */
758 tsk->flags |= PF_EXITPIDONE;
759 set_current_state(TASK_UNINTERRUPTIBLE);
760 schedule();
761 }
762
763 exit_signals(tsk); /* sets PF_EXITING */
764 /*
765 * Ensure that all new tsk->pi_lock acquisitions must observe
766 * PF_EXITING. Serializes against futex.c:attach_to_pi_owner().
767 */
768 smp_mb();
769 /*
770 * Ensure that we must observe the pi_state in exit_mm() ->
771 * mm_release() -> exit_pi_state_list().
772 */
773 raw_spin_lock_irq(&tsk->pi_lock);
774 raw_spin_unlock_irq(&tsk->pi_lock);
775
776 if (unlikely(in_atomic())) {
777 pr_info("note: %s[%d] exited with preempt_count %d\n",
778 current->comm, task_pid_nr(current),
779 preempt_count());
780 preempt_count_set(PREEMPT_ENABLED);
781 }
782
783 /* sync mm's RSS info before statistics gathering */
784 if (tsk->mm)
785 sync_mm_rss(tsk->mm);
786 acct_update_integrals(tsk);
787 group_dead = atomic_dec_and_test(&tsk->signal->live);
788 if (group_dead) {
789#ifdef CONFIG_POSIX_TIMERS
790 hrtimer_cancel(&tsk->signal->real_timer);
791 exit_itimers(tsk->signal);
792#endif
793 if (tsk->mm)
794 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
795 }
796 acct_collect(code, group_dead);
797 if (group_dead)
798 tty_audit_exit();
799 audit_free(tsk);
800
801 tsk->exit_code = code;
802 taskstats_exit(tsk, group_dead);
803
804 exit_mm();
805
806 if (group_dead)
807 acct_process();
808 trace_sched_process_exit(tsk);
809
810 exit_sem(tsk);
811 exit_shm(tsk);
812 exit_files(tsk);
813 exit_fs(tsk);
814 if (group_dead)
815 disassociate_ctty(1);
816 exit_task_namespaces(tsk);
817 exit_task_work(tsk);
818 exit_thread(tsk);
819 exit_umh(tsk);
820
821 /*
822 * Flush inherited counters to the parent - before the parent
823 * gets woken up by child-exit notifications.
824 *
825 * because of cgroup mode, must be called before cgroup_exit()
826 */
827 perf_event_exit_task(tsk);
828
829 sched_autogroup_exit_task(tsk);
830 cgroup_exit(tsk);
831
832 /*
833 * FIXME: do that only when needed, using sched_exit tracepoint
834 */
835 flush_ptrace_hw_breakpoint(tsk);
836
837 exit_tasks_rcu_start();
838 exit_notify(tsk, group_dead);
839 proc_exit_connector(tsk);
840 mpol_put_task_policy(tsk);
841#ifdef CONFIG_FUTEX
842 if (unlikely(current->pi_state_cache))
843 kfree(current->pi_state_cache);
844#endif
845 /*
846 * Make sure we are holding no locks:
847 */
848 debug_check_no_locks_held();
849 /*
850 * We can do this unlocked here. The futex code uses this flag
851 * just to verify whether the pi state cleanup has been done
852 * or not. In the worst case it loops once more.
853 */
854 tsk->flags |= PF_EXITPIDONE;
855
856 if (tsk->io_context)
857 exit_io_context(tsk);
858
859 if (tsk->splice_pipe)
860 free_pipe_info(tsk->splice_pipe);
861
862 if (tsk->task_frag.page)
863 put_page(tsk->task_frag.page);
864
865 validate_creds_for_do_exit(tsk);
866
867 check_stack_usage();
868 preempt_disable();
869 if (tsk->nr_dirtied)
870 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
871 exit_rcu();
872 exit_tasks_rcu_finish();
873
874 lockdep_free_task(tsk);
875 do_task_dead();
876}
877EXPORT_SYMBOL_GPL(do_exit);
878
879void complete_and_exit(struct completion *comp, long code)
880{
881 if (comp)
882 complete(comp);
883
884 do_exit(code);
885}
886EXPORT_SYMBOL(complete_and_exit);
887
888SYSCALL_DEFINE1(exit, int, error_code)
889{
890 do_exit((error_code&0xff)<<8);
891}
892
893/*
894 * Take down every thread in the group. This is called by fatal signals
895 * as well as by sys_exit_group (below).
896 */
897void
898do_group_exit(int exit_code)
899{
900 struct signal_struct *sig = current->signal;
901
902 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
903
904 if (signal_group_exit(sig))
905 exit_code = sig->group_exit_code;
906 else if (!thread_group_empty(current)) {
907 struct sighand_struct *const sighand = current->sighand;
908
909 spin_lock_irq(&sighand->siglock);
910 if (signal_group_exit(sig))
911 /* Another thread got here before we took the lock. */
912 exit_code = sig->group_exit_code;
913 else {
914 sig->group_exit_code = exit_code;
915 sig->flags = SIGNAL_GROUP_EXIT;
916 zap_other_threads(current);
917 }
918 spin_unlock_irq(&sighand->siglock);
919 }
920
921 do_exit(exit_code);
922 /* NOTREACHED */
923}
924
925/*
926 * this kills every thread in the thread group. Note that any externally
927 * wait4()-ing process will get the correct exit code - even if this
928 * thread is not the thread group leader.
929 */
930SYSCALL_DEFINE1(exit_group, int, error_code)
931{
932 do_group_exit((error_code & 0xff) << 8);
933 /* NOTREACHED */
934 return 0;
935}
936
937struct waitid_info {
938 pid_t pid;
939 uid_t uid;
940 int status;
941 int cause;
942};
943
944struct wait_opts {
945 enum pid_type wo_type;
946 int wo_flags;
947 struct pid *wo_pid;
948
949 struct waitid_info *wo_info;
950 int wo_stat;
951 struct rusage *wo_rusage;
952
953 wait_queue_entry_t child_wait;
954 int notask_error;
955};
956
957static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
958{
959 return wo->wo_type == PIDTYPE_MAX ||
960 task_pid_type(p, wo->wo_type) == wo->wo_pid;
961}
962
963static int
964eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
965{
966 if (!eligible_pid(wo, p))
967 return 0;
968
969 /*
970 * Wait for all children (clone and not) if __WALL is set or
971 * if it is traced by us.
972 */
973 if (ptrace || (wo->wo_flags & __WALL))
974 return 1;
975
976 /*
977 * Otherwise, wait for clone children *only* if __WCLONE is set;
978 * otherwise, wait for non-clone children *only*.
979 *
980 * Note: a "clone" child here is one that reports to its parent
981 * using a signal other than SIGCHLD, or a non-leader thread which
982 * we can only see if it is traced by us.
983 */
984 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
985 return 0;
986
987 return 1;
988}
989
990/*
991 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
992 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
993 * the lock and this task is uninteresting. If we return nonzero, we have
994 * released the lock and the system call should return.
995 */
996static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
997{
998 int state, status;
999 pid_t pid = task_pid_vnr(p);
1000 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1001 struct waitid_info *infop;
1002
1003 if (!likely(wo->wo_flags & WEXITED))
1004 return 0;
1005
1006 if (unlikely(wo->wo_flags & WNOWAIT)) {
1007 status = p->exit_code;
1008 get_task_struct(p);
1009 read_unlock(&tasklist_lock);
1010 sched_annotate_sleep();
1011 if (wo->wo_rusage)
1012 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1013 put_task_struct(p);
1014 goto out_info;
1015 }
1016 /*
1017 * Move the task's state to DEAD/TRACE, only one thread can do this.
1018 */
1019 state = (ptrace_reparented(p) && thread_group_leader(p)) ?
1020 EXIT_TRACE : EXIT_DEAD;
1021 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1022 return 0;
1023 /*
1024 * We own this thread, nobody else can reap it.
1025 */
1026 read_unlock(&tasklist_lock);
1027 sched_annotate_sleep();
1028
1029 /*
1030 * Check thread_group_leader() to exclude the traced sub-threads.
1031 */
1032 if (state == EXIT_DEAD && thread_group_leader(p)) {
1033 struct signal_struct *sig = p->signal;
1034 struct signal_struct *psig = current->signal;
1035 unsigned long maxrss;
1036 u64 tgutime, tgstime;
1037
1038 /*
1039 * The resource counters for the group leader are in its
1040 * own task_struct. Those for dead threads in the group
1041 * are in its signal_struct, as are those for the child
1042 * processes it has previously reaped. All these
1043 * accumulate in the parent's signal_struct c* fields.
1044 *
1045 * We don't bother to take a lock here to protect these
1046 * p->signal fields because the whole thread group is dead
1047 * and nobody can change them.
1048 *
1049 * psig->stats_lock also protects us from our sub-theads
1050 * which can reap other children at the same time. Until
1051 * we change k_getrusage()-like users to rely on this lock
1052 * we have to take ->siglock as well.
1053 *
1054 * We use thread_group_cputime_adjusted() to get times for
1055 * the thread group, which consolidates times for all threads
1056 * in the group including the group leader.
1057 */
1058 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1059 spin_lock_irq(¤t->sighand->siglock);
1060 write_seqlock(&psig->stats_lock);
1061 psig->cutime += tgutime + sig->cutime;
1062 psig->cstime += tgstime + sig->cstime;
1063 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1064 psig->cmin_flt +=
1065 p->min_flt + sig->min_flt + sig->cmin_flt;
1066 psig->cmaj_flt +=
1067 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1068 psig->cnvcsw +=
1069 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1070 psig->cnivcsw +=
1071 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1072 psig->cinblock +=
1073 task_io_get_inblock(p) +
1074 sig->inblock + sig->cinblock;
1075 psig->coublock +=
1076 task_io_get_oublock(p) +
1077 sig->oublock + sig->coublock;
1078 maxrss = max(sig->maxrss, sig->cmaxrss);
1079 if (psig->cmaxrss < maxrss)
1080 psig->cmaxrss = maxrss;
1081 task_io_accounting_add(&psig->ioac, &p->ioac);
1082 task_io_accounting_add(&psig->ioac, &sig->ioac);
1083 write_sequnlock(&psig->stats_lock);
1084 spin_unlock_irq(¤t->sighand->siglock);
1085 }
1086
1087 if (wo->wo_rusage)
1088 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1089 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1090 ? p->signal->group_exit_code : p->exit_code;
1091 wo->wo_stat = status;
1092
1093 if (state == EXIT_TRACE) {
1094 write_lock_irq(&tasklist_lock);
1095 /* We dropped tasklist, ptracer could die and untrace */
1096 ptrace_unlink(p);
1097
1098 /* If parent wants a zombie, don't release it now */
1099 state = EXIT_ZOMBIE;
1100 if (do_notify_parent(p, p->exit_signal))
1101 state = EXIT_DEAD;
1102 p->exit_state = state;
1103 write_unlock_irq(&tasklist_lock);
1104 }
1105 if (state == EXIT_DEAD)
1106 release_task(p);
1107
1108out_info:
1109 infop = wo->wo_info;
1110 if (infop) {
1111 if ((status & 0x7f) == 0) {
1112 infop->cause = CLD_EXITED;
1113 infop->status = status >> 8;
1114 } else {
1115 infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1116 infop->status = status & 0x7f;
1117 }
1118 infop->pid = pid;
1119 infop->uid = uid;
1120 }
1121
1122 return pid;
1123}
1124
1125static int *task_stopped_code(struct task_struct *p, bool ptrace)
1126{
1127 if (ptrace) {
1128 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING))
1129 return &p->exit_code;
1130 } else {
1131 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1132 return &p->signal->group_exit_code;
1133 }
1134 return NULL;
1135}
1136
1137/**
1138 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1139 * @wo: wait options
1140 * @ptrace: is the wait for ptrace
1141 * @p: task to wait for
1142 *
1143 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1144 *
1145 * CONTEXT:
1146 * read_lock(&tasklist_lock), which is released if return value is
1147 * non-zero. Also, grabs and releases @p->sighand->siglock.
1148 *
1149 * RETURNS:
1150 * 0 if wait condition didn't exist and search for other wait conditions
1151 * should continue. Non-zero return, -errno on failure and @p's pid on
1152 * success, implies that tasklist_lock is released and wait condition
1153 * search should terminate.
1154 */
1155static int wait_task_stopped(struct wait_opts *wo,
1156 int ptrace, struct task_struct *p)
1157{
1158 struct waitid_info *infop;
1159 int exit_code, *p_code, why;
1160 uid_t uid = 0; /* unneeded, required by compiler */
1161 pid_t pid;
1162
1163 /*
1164 * Traditionally we see ptrace'd stopped tasks regardless of options.
1165 */
1166 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1167 return 0;
1168
1169 if (!task_stopped_code(p, ptrace))
1170 return 0;
1171
1172 exit_code = 0;
1173 spin_lock_irq(&p->sighand->siglock);
1174
1175 p_code = task_stopped_code(p, ptrace);
1176 if (unlikely(!p_code))
1177 goto unlock_sig;
1178
1179 exit_code = *p_code;
1180 if (!exit_code)
1181 goto unlock_sig;
1182
1183 if (!unlikely(wo->wo_flags & WNOWAIT))
1184 *p_code = 0;
1185
1186 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1187unlock_sig:
1188 spin_unlock_irq(&p->sighand->siglock);
1189 if (!exit_code)
1190 return 0;
1191
1192 /*
1193 * Now we are pretty sure this task is interesting.
1194 * Make sure it doesn't get reaped out from under us while we
1195 * give up the lock and then examine it below. We don't want to
1196 * keep holding onto the tasklist_lock while we call getrusage and
1197 * possibly take page faults for user memory.
1198 */
1199 get_task_struct(p);
1200 pid = task_pid_vnr(p);
1201 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1202 read_unlock(&tasklist_lock);
1203 sched_annotate_sleep();
1204 if (wo->wo_rusage)
1205 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1206 put_task_struct(p);
1207
1208 if (likely(!(wo->wo_flags & WNOWAIT)))
1209 wo->wo_stat = (exit_code << 8) | 0x7f;
1210
1211 infop = wo->wo_info;
1212 if (infop) {
1213 infop->cause = why;
1214 infop->status = exit_code;
1215 infop->pid = pid;
1216 infop->uid = uid;
1217 }
1218 return pid;
1219}
1220
1221/*
1222 * Handle do_wait work for one task in a live, non-stopped state.
1223 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1224 * the lock and this task is uninteresting. If we return nonzero, we have
1225 * released the lock and the system call should return.
1226 */
1227static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1228{
1229 struct waitid_info *infop;
1230 pid_t pid;
1231 uid_t uid;
1232
1233 if (!unlikely(wo->wo_flags & WCONTINUED))
1234 return 0;
1235
1236 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1237 return 0;
1238
1239 spin_lock_irq(&p->sighand->siglock);
1240 /* Re-check with the lock held. */
1241 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1242 spin_unlock_irq(&p->sighand->siglock);
1243 return 0;
1244 }
1245 if (!unlikely(wo->wo_flags & WNOWAIT))
1246 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1247 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1248 spin_unlock_irq(&p->sighand->siglock);
1249
1250 pid = task_pid_vnr(p);
1251 get_task_struct(p);
1252 read_unlock(&tasklist_lock);
1253 sched_annotate_sleep();
1254 if (wo->wo_rusage)
1255 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1256 put_task_struct(p);
1257
1258 infop = wo->wo_info;
1259 if (!infop) {
1260 wo->wo_stat = 0xffff;
1261 } else {
1262 infop->cause = CLD_CONTINUED;
1263 infop->pid = pid;
1264 infop->uid = uid;
1265 infop->status = SIGCONT;
1266 }
1267 return pid;
1268}
1269
1270/*
1271 * Consider @p for a wait by @parent.
1272 *
1273 * -ECHILD should be in ->notask_error before the first call.
1274 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1275 * Returns zero if the search for a child should continue;
1276 * then ->notask_error is 0 if @p is an eligible child,
1277 * or still -ECHILD.
1278 */
1279static int wait_consider_task(struct wait_opts *wo, int ptrace,
1280 struct task_struct *p)
1281{
1282 /*
1283 * We can race with wait_task_zombie() from another thread.
1284 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1285 * can't confuse the checks below.
1286 */
1287 int exit_state = READ_ONCE(p->exit_state);
1288 int ret;
1289
1290 if (unlikely(exit_state == EXIT_DEAD))
1291 return 0;
1292
1293 ret = eligible_child(wo, ptrace, p);
1294 if (!ret)
1295 return ret;
1296
1297 if (unlikely(exit_state == EXIT_TRACE)) {
1298 /*
1299 * ptrace == 0 means we are the natural parent. In this case
1300 * we should clear notask_error, debugger will notify us.
1301 */
1302 if (likely(!ptrace))
1303 wo->notask_error = 0;
1304 return 0;
1305 }
1306
1307 if (likely(!ptrace) && unlikely(p->ptrace)) {
1308 /*
1309 * If it is traced by its real parent's group, just pretend
1310 * the caller is ptrace_do_wait() and reap this child if it
1311 * is zombie.
1312 *
1313 * This also hides group stop state from real parent; otherwise
1314 * a single stop can be reported twice as group and ptrace stop.
1315 * If a ptracer wants to distinguish these two events for its
1316 * own children it should create a separate process which takes
1317 * the role of real parent.
1318 */
1319 if (!ptrace_reparented(p))
1320 ptrace = 1;
1321 }
1322
1323 /* slay zombie? */
1324 if (exit_state == EXIT_ZOMBIE) {
1325 /* we don't reap group leaders with subthreads */
1326 if (!delay_group_leader(p)) {
1327 /*
1328 * A zombie ptracee is only visible to its ptracer.
1329 * Notification and reaping will be cascaded to the
1330 * real parent when the ptracer detaches.
1331 */
1332 if (unlikely(ptrace) || likely(!p->ptrace))
1333 return wait_task_zombie(wo, p);
1334 }
1335
1336 /*
1337 * Allow access to stopped/continued state via zombie by
1338 * falling through. Clearing of notask_error is complex.
1339 *
1340 * When !@ptrace:
1341 *
1342 * If WEXITED is set, notask_error should naturally be
1343 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1344 * so, if there are live subthreads, there are events to
1345 * wait for. If all subthreads are dead, it's still safe
1346 * to clear - this function will be called again in finite
1347 * amount time once all the subthreads are released and
1348 * will then return without clearing.
1349 *
1350 * When @ptrace:
1351 *
1352 * Stopped state is per-task and thus can't change once the
1353 * target task dies. Only continued and exited can happen.
1354 * Clear notask_error if WCONTINUED | WEXITED.
1355 */
1356 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1357 wo->notask_error = 0;
1358 } else {
1359 /*
1360 * @p is alive and it's gonna stop, continue or exit, so
1361 * there always is something to wait for.
1362 */
1363 wo->notask_error = 0;
1364 }
1365
1366 /*
1367 * Wait for stopped. Depending on @ptrace, different stopped state
1368 * is used and the two don't interact with each other.
1369 */
1370 ret = wait_task_stopped(wo, ptrace, p);
1371 if (ret)
1372 return ret;
1373
1374 /*
1375 * Wait for continued. There's only one continued state and the
1376 * ptracer can consume it which can confuse the real parent. Don't
1377 * use WCONTINUED from ptracer. You don't need or want it.
1378 */
1379 return wait_task_continued(wo, p);
1380}
1381
1382/*
1383 * Do the work of do_wait() for one thread in the group, @tsk.
1384 *
1385 * -ECHILD should be in ->notask_error before the first call.
1386 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1387 * Returns zero if the search for a child should continue; then
1388 * ->notask_error is 0 if there were any eligible children,
1389 * or still -ECHILD.
1390 */
1391static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1392{
1393 struct task_struct *p;
1394
1395 list_for_each_entry(p, &tsk->children, sibling) {
1396 int ret = wait_consider_task(wo, 0, p);
1397
1398 if (ret)
1399 return ret;
1400 }
1401
1402 return 0;
1403}
1404
1405static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1406{
1407 struct task_struct *p;
1408
1409 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1410 int ret = wait_consider_task(wo, 1, p);
1411
1412 if (ret)
1413 return ret;
1414 }
1415
1416 return 0;
1417}
1418
1419static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode,
1420 int sync, void *key)
1421{
1422 struct wait_opts *wo = container_of(wait, struct wait_opts,
1423 child_wait);
1424 struct task_struct *p = key;
1425
1426 if (!eligible_pid(wo, p))
1427 return 0;
1428
1429 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1430 return 0;
1431
1432 return default_wake_function(wait, mode, sync, key);
1433}
1434
1435void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1436{
1437 __wake_up_sync_key(&parent->signal->wait_chldexit,
1438 TASK_INTERRUPTIBLE, 1, p);
1439}
1440
1441static long do_wait(struct wait_opts *wo)
1442{
1443 struct task_struct *tsk;
1444 int retval;
1445
1446 trace_sched_process_wait(wo->wo_pid);
1447
1448 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1449 wo->child_wait.private = current;
1450 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1451repeat:
1452 /*
1453 * If there is nothing that can match our criteria, just get out.
1454 * We will clear ->notask_error to zero if we see any child that
1455 * might later match our criteria, even if we are not able to reap
1456 * it yet.
1457 */
1458 wo->notask_error = -ECHILD;
1459 if ((wo->wo_type < PIDTYPE_MAX) &&
1460 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1461 goto notask;
1462
1463 set_current_state(TASK_INTERRUPTIBLE);
1464 read_lock(&tasklist_lock);
1465 tsk = current;
1466 do {
1467 retval = do_wait_thread(wo, tsk);
1468 if (retval)
1469 goto end;
1470
1471 retval = ptrace_do_wait(wo, tsk);
1472 if (retval)
1473 goto end;
1474
1475 if (wo->wo_flags & __WNOTHREAD)
1476 break;
1477 } while_each_thread(current, tsk);
1478 read_unlock(&tasklist_lock);
1479
1480notask:
1481 retval = wo->notask_error;
1482 if (!retval && !(wo->wo_flags & WNOHANG)) {
1483 retval = -ERESTARTSYS;
1484 if (!signal_pending(current)) {
1485 schedule();
1486 goto repeat;
1487 }
1488 }
1489end:
1490 __set_current_state(TASK_RUNNING);
1491 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1492 return retval;
1493}
1494
1495static struct pid *pidfd_get_pid(unsigned int fd)
1496{
1497 struct fd f;
1498 struct pid *pid;
1499
1500 f = fdget(fd);
1501 if (!f.file)
1502 return ERR_PTR(-EBADF);
1503
1504 pid = pidfd_pid(f.file);
1505 if (!IS_ERR(pid))
1506 get_pid(pid);
1507
1508 fdput(f);
1509 return pid;
1510}
1511
1512static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
1513 int options, struct rusage *ru)
1514{
1515 struct wait_opts wo;
1516 struct pid *pid = NULL;
1517 enum pid_type type;
1518 long ret;
1519
1520 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
1521 __WNOTHREAD|__WCLONE|__WALL))
1522 return -EINVAL;
1523 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1524 return -EINVAL;
1525
1526 switch (which) {
1527 case P_ALL:
1528 type = PIDTYPE_MAX;
1529 break;
1530 case P_PID:
1531 type = PIDTYPE_PID;
1532 if (upid <= 0)
1533 return -EINVAL;
1534
1535 pid = find_get_pid(upid);
1536 break;
1537 case P_PGID:
1538 type = PIDTYPE_PGID;
1539 if (upid < 0)
1540 return -EINVAL;
1541
1542 if (upid)
1543 pid = find_get_pid(upid);
1544 else
1545 pid = get_task_pid(current, PIDTYPE_PGID);
1546 break;
1547 case P_PIDFD:
1548 type = PIDTYPE_PID;
1549 if (upid < 0)
1550 return -EINVAL;
1551
1552 pid = pidfd_get_pid(upid);
1553 if (IS_ERR(pid))
1554 return PTR_ERR(pid);
1555 break;
1556 default:
1557 return -EINVAL;
1558 }
1559
1560 wo.wo_type = type;
1561 wo.wo_pid = pid;
1562 wo.wo_flags = options;
1563 wo.wo_info = infop;
1564 wo.wo_rusage = ru;
1565 ret = do_wait(&wo);
1566
1567 put_pid(pid);
1568 return ret;
1569}
1570
1571SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1572 infop, int, options, struct rusage __user *, ru)
1573{
1574 struct rusage r;
1575 struct waitid_info info = {.status = 0};
1576 long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
1577 int signo = 0;
1578
1579 if (err > 0) {
1580 signo = SIGCHLD;
1581 err = 0;
1582 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1583 return -EFAULT;
1584 }
1585 if (!infop)
1586 return err;
1587
1588 if (!user_access_begin(infop, sizeof(*infop)))
1589 return -EFAULT;
1590
1591 unsafe_put_user(signo, &infop->si_signo, Efault);
1592 unsafe_put_user(0, &infop->si_errno, Efault);
1593 unsafe_put_user(info.cause, &infop->si_code, Efault);
1594 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1595 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1596 unsafe_put_user(info.status, &infop->si_status, Efault);
1597 user_access_end();
1598 return err;
1599Efault:
1600 user_access_end();
1601 return -EFAULT;
1602}
1603
1604long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
1605 struct rusage *ru)
1606{
1607 struct wait_opts wo;
1608 struct pid *pid = NULL;
1609 enum pid_type type;
1610 long ret;
1611
1612 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1613 __WNOTHREAD|__WCLONE|__WALL))
1614 return -EINVAL;
1615
1616 /* -INT_MIN is not defined */
1617 if (upid == INT_MIN)
1618 return -ESRCH;
1619
1620 if (upid == -1)
1621 type = PIDTYPE_MAX;
1622 else if (upid < 0) {
1623 type = PIDTYPE_PGID;
1624 pid = find_get_pid(-upid);
1625 } else if (upid == 0) {
1626 type = PIDTYPE_PGID;
1627 pid = get_task_pid(current, PIDTYPE_PGID);
1628 } else /* upid > 0 */ {
1629 type = PIDTYPE_PID;
1630 pid = find_get_pid(upid);
1631 }
1632
1633 wo.wo_type = type;
1634 wo.wo_pid = pid;
1635 wo.wo_flags = options | WEXITED;
1636 wo.wo_info = NULL;
1637 wo.wo_stat = 0;
1638 wo.wo_rusage = ru;
1639 ret = do_wait(&wo);
1640 put_pid(pid);
1641 if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
1642 ret = -EFAULT;
1643
1644 return ret;
1645}
1646
1647SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1648 int, options, struct rusage __user *, ru)
1649{
1650 struct rusage r;
1651 long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL);
1652
1653 if (err > 0) {
1654 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1655 return -EFAULT;
1656 }
1657 return err;
1658}
1659
1660#ifdef __ARCH_WANT_SYS_WAITPID
1661
1662/*
1663 * sys_waitpid() remains for compatibility. waitpid() should be
1664 * implemented by calling sys_wait4() from libc.a.
1665 */
1666SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1667{
1668 return kernel_wait4(pid, stat_addr, options, NULL);
1669}
1670
1671#endif
1672
1673#ifdef CONFIG_COMPAT
1674COMPAT_SYSCALL_DEFINE4(wait4,
1675 compat_pid_t, pid,
1676 compat_uint_t __user *, stat_addr,
1677 int, options,
1678 struct compat_rusage __user *, ru)
1679{
1680 struct rusage r;
1681 long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL);
1682 if (err > 0) {
1683 if (ru && put_compat_rusage(&r, ru))
1684 return -EFAULT;
1685 }
1686 return err;
1687}
1688
1689COMPAT_SYSCALL_DEFINE5(waitid,
1690 int, which, compat_pid_t, pid,
1691 struct compat_siginfo __user *, infop, int, options,
1692 struct compat_rusage __user *, uru)
1693{
1694 struct rusage ru;
1695 struct waitid_info info = {.status = 0};
1696 long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);
1697 int signo = 0;
1698 if (err > 0) {
1699 signo = SIGCHLD;
1700 err = 0;
1701 if (uru) {
1702 /* kernel_waitid() overwrites everything in ru */
1703 if (COMPAT_USE_64BIT_TIME)
1704 err = copy_to_user(uru, &ru, sizeof(ru));
1705 else
1706 err = put_compat_rusage(&ru, uru);
1707 if (err)
1708 return -EFAULT;
1709 }
1710 }
1711
1712 if (!infop)
1713 return err;
1714
1715 if (!user_access_begin(infop, sizeof(*infop)))
1716 return -EFAULT;
1717
1718 unsafe_put_user(signo, &infop->si_signo, Efault);
1719 unsafe_put_user(0, &infop->si_errno, Efault);
1720 unsafe_put_user(info.cause, &infop->si_code, Efault);
1721 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1722 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1723 unsafe_put_user(info.status, &infop->si_status, Efault);
1724 user_access_end();
1725 return err;
1726Efault:
1727 user_access_end();
1728 return -EFAULT;
1729}
1730#endif
1731
1732__weak void abort(void)
1733{
1734 BUG();
1735
1736 /* if that doesn't kill us, halt */
1737 panic("Oops failed to kill thread");
1738}
1739EXPORT_SYMBOL(abort);