Loading...
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/binfmts.h>
24#include <linux/nsproxy.h>
25#include <linux/pid_namespace.h>
26#include <linux/ptrace.h>
27#include <linux/profile.h>
28#include <linux/mount.h>
29#include <linux/proc_fs.h>
30#include <linux/kthread.h>
31#include <linux/mempolicy.h>
32#include <linux/taskstats_kern.h>
33#include <linux/delayacct.h>
34#include <linux/freezer.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 * If we are the last child process in a pid namespace to be
77 * reaped, notify the reaper sleeping zap_pid_ns_processes().
78 */
79 if (IS_ENABLED(CONFIG_PID_NS)) {
80 struct task_struct *parent = p->real_parent;
81
82 if ((task_active_pid_ns(parent)->child_reaper == parent) &&
83 list_empty(&parent->children) &&
84 (parent->flags & PF_EXITING))
85 wake_up_process(parent);
86 }
87 }
88 list_del_rcu(&p->thread_group);
89}
90
91/*
92 * This function expects the tasklist_lock write-locked.
93 */
94static void __exit_signal(struct task_struct *tsk)
95{
96 struct signal_struct *sig = tsk->signal;
97 bool group_dead = thread_group_leader(tsk);
98 struct sighand_struct *sighand;
99 struct tty_struct *uninitialized_var(tty);
100
101 sighand = rcu_dereference_check(tsk->sighand,
102 lockdep_tasklist_lock_is_held());
103 spin_lock(&sighand->siglock);
104
105 posix_cpu_timers_exit(tsk);
106 if (group_dead) {
107 posix_cpu_timers_exit_group(tsk);
108 tty = sig->tty;
109 sig->tty = NULL;
110 } else {
111 /*
112 * This can only happen if the caller is de_thread().
113 * FIXME: this is the temporary hack, we should teach
114 * posix-cpu-timers to handle this case correctly.
115 */
116 if (unlikely(has_group_leader_pid(tsk)))
117 posix_cpu_timers_exit_group(tsk);
118
119 /*
120 * If there is any task waiting for the group exit
121 * then notify it:
122 */
123 if (sig->notify_count > 0 && !--sig->notify_count)
124 wake_up_process(sig->group_exit_task);
125
126 if (tsk == sig->curr_target)
127 sig->curr_target = next_thread(tsk);
128 /*
129 * Accumulate here the counters for all threads but the
130 * group leader as they die, so they can be added into
131 * the process-wide totals when those are taken.
132 * The group leader stays around as a zombie as long
133 * as there are other threads. When it gets reaped,
134 * the exit.c code will add its counts into these totals.
135 * We won't ever get here for the group leader, since it
136 * will have been the last reference on the signal_struct.
137 */
138 sig->utime += tsk->utime;
139 sig->stime += tsk->stime;
140 sig->gtime += tsk->gtime;
141 sig->min_flt += tsk->min_flt;
142 sig->maj_flt += tsk->maj_flt;
143 sig->nvcsw += tsk->nvcsw;
144 sig->nivcsw += tsk->nivcsw;
145 sig->inblock += task_io_get_inblock(tsk);
146 sig->oublock += task_io_get_oublock(tsk);
147 task_io_accounting_add(&sig->ioac, &tsk->ioac);
148 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
149 }
150
151 sig->nr_threads--;
152 __unhash_process(tsk, group_dead);
153
154 /*
155 * Do this under ->siglock, we can race with another thread
156 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
157 */
158 flush_sigqueue(&tsk->pending);
159 tsk->sighand = NULL;
160 spin_unlock(&sighand->siglock);
161
162 __cleanup_sighand(sighand);
163 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
164 if (group_dead) {
165 flush_sigqueue(&sig->shared_pending);
166 tty_kref_put(tty);
167 }
168}
169
170static void delayed_put_task_struct(struct rcu_head *rhp)
171{
172 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
173
174 perf_event_delayed_put(tsk);
175 trace_sched_process_free(tsk);
176 put_task_struct(tsk);
177}
178
179
180void release_task(struct task_struct * p)
181{
182 struct task_struct *leader;
183 int zap_leader;
184repeat:
185 /* don't need to get the RCU readlock here - the process is dead and
186 * can't be modifying its own credentials. But shut RCU-lockdep up */
187 rcu_read_lock();
188 atomic_dec(&__task_cred(p)->user->processes);
189 rcu_read_unlock();
190
191 proc_flush_task(p);
192
193 write_lock_irq(&tasklist_lock);
194 ptrace_release_task(p);
195 __exit_signal(p);
196
197 /*
198 * If we are the last non-leader member of the thread
199 * group, and the leader is zombie, then notify the
200 * group leader's parent process. (if it wants notification.)
201 */
202 zap_leader = 0;
203 leader = p->group_leader;
204 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
205 /*
206 * If we were the last child thread and the leader has
207 * exited already, and the leader's parent ignores SIGCHLD,
208 * then we are the one who should release the leader.
209 */
210 zap_leader = do_notify_parent(leader, leader->exit_signal);
211 if (zap_leader)
212 leader->exit_state = EXIT_DEAD;
213 }
214
215 write_unlock_irq(&tasklist_lock);
216 release_thread(p);
217 call_rcu(&p->rcu, delayed_put_task_struct);
218
219 p = leader;
220 if (unlikely(zap_leader))
221 goto repeat;
222}
223
224/*
225 * This checks not only the pgrp, but falls back on the pid if no
226 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
227 * without this...
228 *
229 * The caller must hold rcu lock or the tasklist lock.
230 */
231struct pid *session_of_pgrp(struct pid *pgrp)
232{
233 struct task_struct *p;
234 struct pid *sid = NULL;
235
236 p = pid_task(pgrp, PIDTYPE_PGID);
237 if (p == NULL)
238 p = pid_task(pgrp, PIDTYPE_PID);
239 if (p != NULL)
240 sid = task_session(p);
241
242 return sid;
243}
244
245/*
246 * Determine if a process group is "orphaned", according to the POSIX
247 * definition in 2.2.2.52. Orphaned process groups are not to be affected
248 * by terminal-generated stop signals. Newly orphaned process groups are
249 * to receive a SIGHUP and a SIGCONT.
250 *
251 * "I ask you, have you ever known what it is to be an orphan?"
252 */
253static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
254{
255 struct task_struct *p;
256
257 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
258 if ((p == ignored_task) ||
259 (p->exit_state && thread_group_empty(p)) ||
260 is_global_init(p->real_parent))
261 continue;
262
263 if (task_pgrp(p->real_parent) != pgrp &&
264 task_session(p->real_parent) == task_session(p))
265 return 0;
266 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
267
268 return 1;
269}
270
271int is_current_pgrp_orphaned(void)
272{
273 int retval;
274
275 read_lock(&tasklist_lock);
276 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
277 read_unlock(&tasklist_lock);
278
279 return retval;
280}
281
282static bool has_stopped_jobs(struct pid *pgrp)
283{
284 struct task_struct *p;
285
286 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
287 if (p->signal->flags & SIGNAL_STOP_STOPPED)
288 return true;
289 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
290
291 return false;
292}
293
294/*
295 * Check to see if any process groups have become orphaned as
296 * a result of our exiting, and if they have any stopped jobs,
297 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
298 */
299static void
300kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
301{
302 struct pid *pgrp = task_pgrp(tsk);
303 struct task_struct *ignored_task = tsk;
304
305 if (!parent)
306 /* exit: our father is in a different pgrp than
307 * we are and we were the only connection outside.
308 */
309 parent = tsk->real_parent;
310 else
311 /* reparent: our child is in a different pgrp than
312 * we are, and it was the only connection outside.
313 */
314 ignored_task = NULL;
315
316 if (task_pgrp(parent) != pgrp &&
317 task_session(parent) == task_session(tsk) &&
318 will_become_orphaned_pgrp(pgrp, ignored_task) &&
319 has_stopped_jobs(pgrp)) {
320 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
321 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
322 }
323}
324
325/**
326 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
327 *
328 * If a kernel thread is launched as a result of a system call, or if
329 * it ever exits, it should generally reparent itself to kthreadd so it
330 * isn't in the way of other processes and is correctly cleaned up on exit.
331 *
332 * The various task state such as scheduling policy and priority may have
333 * been inherited from a user process, so we reset them to sane values here.
334 *
335 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
336 */
337static void reparent_to_kthreadd(void)
338{
339 write_lock_irq(&tasklist_lock);
340
341 ptrace_unlink(current);
342 /* Reparent to init */
343 current->real_parent = current->parent = kthreadd_task;
344 list_move_tail(¤t->sibling, ¤t->real_parent->children);
345
346 /* Set the exit signal to SIGCHLD so we signal init on exit */
347 current->exit_signal = SIGCHLD;
348
349 if (task_nice(current) < 0)
350 set_user_nice(current, 0);
351 /* cpus_allowed? */
352 /* rt_priority? */
353 /* signals? */
354 memcpy(current->signal->rlim, init_task.signal->rlim,
355 sizeof(current->signal->rlim));
356
357 atomic_inc(&init_cred.usage);
358 commit_creds(&init_cred);
359 write_unlock_irq(&tasklist_lock);
360}
361
362void __set_special_pids(struct pid *pid)
363{
364 struct task_struct *curr = current->group_leader;
365
366 if (task_session(curr) != pid)
367 change_pid(curr, PIDTYPE_SID, pid);
368
369 if (task_pgrp(curr) != pid)
370 change_pid(curr, PIDTYPE_PGID, pid);
371}
372
373static void set_special_pids(struct pid *pid)
374{
375 write_lock_irq(&tasklist_lock);
376 __set_special_pids(pid);
377 write_unlock_irq(&tasklist_lock);
378}
379
380/*
381 * Let kernel threads use this to say that they allow a certain signal.
382 * Must not be used if kthread was cloned with CLONE_SIGHAND.
383 */
384int allow_signal(int sig)
385{
386 if (!valid_signal(sig) || sig < 1)
387 return -EINVAL;
388
389 spin_lock_irq(¤t->sighand->siglock);
390 /* This is only needed for daemonize()'ed kthreads */
391 sigdelset(¤t->blocked, sig);
392 /*
393 * Kernel threads handle their own signals. Let the signal code
394 * know it'll be handled, so that they don't get converted to
395 * SIGKILL or just silently dropped.
396 */
397 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
398 recalc_sigpending();
399 spin_unlock_irq(¤t->sighand->siglock);
400 return 0;
401}
402
403EXPORT_SYMBOL(allow_signal);
404
405int disallow_signal(int sig)
406{
407 if (!valid_signal(sig) || sig < 1)
408 return -EINVAL;
409
410 spin_lock_irq(¤t->sighand->siglock);
411 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
412 recalc_sigpending();
413 spin_unlock_irq(¤t->sighand->siglock);
414 return 0;
415}
416
417EXPORT_SYMBOL(disallow_signal);
418
419/*
420 * Put all the gunge required to become a kernel thread without
421 * attached user resources in one place where it belongs.
422 */
423
424void daemonize(const char *name, ...)
425{
426 va_list args;
427 sigset_t blocked;
428
429 va_start(args, name);
430 vsnprintf(current->comm, sizeof(current->comm), name, args);
431 va_end(args);
432
433 /*
434 * If we were started as result of loading a module, close all of the
435 * user space pages. We don't need them, and if we didn't close them
436 * they would be locked into memory.
437 */
438 exit_mm(current);
439 /*
440 * We don't want to get frozen, in case system-wide hibernation
441 * or suspend transition begins right now.
442 */
443 current->flags |= (PF_NOFREEZE | PF_KTHREAD);
444
445 if (current->nsproxy != &init_nsproxy) {
446 get_nsproxy(&init_nsproxy);
447 switch_task_namespaces(current, &init_nsproxy);
448 }
449 set_special_pids(&init_struct_pid);
450 proc_clear_tty(current);
451
452 /* Block and flush all signals */
453 sigfillset(&blocked);
454 sigprocmask(SIG_BLOCK, &blocked, NULL);
455 flush_signals(current);
456
457 /* Become as one with the init task */
458
459 daemonize_fs_struct();
460 exit_files(current);
461 current->files = init_task.files;
462 atomic_inc(¤t->files->count);
463
464 reparent_to_kthreadd();
465}
466
467EXPORT_SYMBOL(daemonize);
468
469static void close_files(struct files_struct * files)
470{
471 int i, j;
472 struct fdtable *fdt;
473
474 j = 0;
475
476 /*
477 * It is safe to dereference the fd table without RCU or
478 * ->file_lock because this is the last reference to the
479 * files structure. But use RCU to shut RCU-lockdep up.
480 */
481 rcu_read_lock();
482 fdt = files_fdtable(files);
483 rcu_read_unlock();
484 for (;;) {
485 unsigned long set;
486 i = j * BITS_PER_LONG;
487 if (i >= fdt->max_fds)
488 break;
489 set = fdt->open_fds[j++];
490 while (set) {
491 if (set & 1) {
492 struct file * file = xchg(&fdt->fd[i], NULL);
493 if (file) {
494 filp_close(file, files);
495 cond_resched();
496 }
497 }
498 i++;
499 set >>= 1;
500 }
501 }
502}
503
504struct files_struct *get_files_struct(struct task_struct *task)
505{
506 struct files_struct *files;
507
508 task_lock(task);
509 files = task->files;
510 if (files)
511 atomic_inc(&files->count);
512 task_unlock(task);
513
514 return files;
515}
516
517void put_files_struct(struct files_struct *files)
518{
519 struct fdtable *fdt;
520
521 if (atomic_dec_and_test(&files->count)) {
522 close_files(files);
523 /*
524 * Free the fd and fdset arrays if we expanded them.
525 * If the fdtable was embedded, pass files for freeing
526 * at the end of the RCU grace period. Otherwise,
527 * you can free files immediately.
528 */
529 rcu_read_lock();
530 fdt = files_fdtable(files);
531 if (fdt != &files->fdtab)
532 kmem_cache_free(files_cachep, files);
533 free_fdtable(fdt);
534 rcu_read_unlock();
535 }
536}
537
538void reset_files_struct(struct files_struct *files)
539{
540 struct task_struct *tsk = current;
541 struct files_struct *old;
542
543 old = tsk->files;
544 task_lock(tsk);
545 tsk->files = files;
546 task_unlock(tsk);
547 put_files_struct(old);
548}
549
550void exit_files(struct task_struct *tsk)
551{
552 struct files_struct * files = tsk->files;
553
554 if (files) {
555 task_lock(tsk);
556 tsk->files = NULL;
557 task_unlock(tsk);
558 put_files_struct(files);
559 }
560}
561
562#ifdef CONFIG_MM_OWNER
563/*
564 * A task is exiting. If it owned this mm, find a new owner for the mm.
565 */
566void mm_update_next_owner(struct mm_struct *mm)
567{
568 struct task_struct *c, *g, *p = current;
569
570retry:
571 /*
572 * If the exiting or execing task is not the owner, it's
573 * someone else's problem.
574 */
575 if (mm->owner != p)
576 return;
577 /*
578 * The current owner is exiting/execing and there are no other
579 * candidates. Do not leave the mm pointing to a possibly
580 * freed task structure.
581 */
582 if (atomic_read(&mm->mm_users) <= 1) {
583 mm->owner = NULL;
584 return;
585 }
586
587 read_lock(&tasklist_lock);
588 /*
589 * Search in the children
590 */
591 list_for_each_entry(c, &p->children, sibling) {
592 if (c->mm == mm)
593 goto assign_new_owner;
594 }
595
596 /*
597 * Search in the siblings
598 */
599 list_for_each_entry(c, &p->real_parent->children, sibling) {
600 if (c->mm == mm)
601 goto assign_new_owner;
602 }
603
604 /*
605 * Search through everything else. We should not get
606 * here often
607 */
608 do_each_thread(g, c) {
609 if (c->mm == mm)
610 goto assign_new_owner;
611 } while_each_thread(g, c);
612
613 read_unlock(&tasklist_lock);
614 /*
615 * We found no owner yet mm_users > 1: this implies that we are
616 * most likely racing with swapoff (try_to_unuse()) or /proc or
617 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
618 */
619 mm->owner = NULL;
620 return;
621
622assign_new_owner:
623 BUG_ON(c == p);
624 get_task_struct(c);
625 /*
626 * The task_lock protects c->mm from changing.
627 * We always want mm->owner->mm == mm
628 */
629 task_lock(c);
630 /*
631 * Delay read_unlock() till we have the task_lock()
632 * to ensure that c does not slip away underneath us
633 */
634 read_unlock(&tasklist_lock);
635 if (c->mm != mm) {
636 task_unlock(c);
637 put_task_struct(c);
638 goto retry;
639 }
640 mm->owner = c;
641 task_unlock(c);
642 put_task_struct(c);
643}
644#endif /* CONFIG_MM_OWNER */
645
646/*
647 * Turn us into a lazy TLB process if we
648 * aren't already..
649 */
650static void exit_mm(struct task_struct * tsk)
651{
652 struct mm_struct *mm = tsk->mm;
653 struct core_state *core_state;
654
655 mm_release(tsk, mm);
656 if (!mm)
657 return;
658 sync_mm_rss(mm);
659 /*
660 * Serialize with any possible pending coredump.
661 * We must hold mmap_sem around checking core_state
662 * and clearing tsk->mm. The core-inducing thread
663 * will increment ->nr_threads for each thread in the
664 * group with ->mm != NULL.
665 */
666 down_read(&mm->mmap_sem);
667 core_state = mm->core_state;
668 if (core_state) {
669 struct core_thread self;
670 up_read(&mm->mmap_sem);
671
672 self.task = tsk;
673 self.next = xchg(&core_state->dumper.next, &self);
674 /*
675 * Implies mb(), the result of xchg() must be visible
676 * to core_state->dumper.
677 */
678 if (atomic_dec_and_test(&core_state->nr_threads))
679 complete(&core_state->startup);
680
681 for (;;) {
682 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
683 if (!self.task) /* see coredump_finish() */
684 break;
685 schedule();
686 }
687 __set_task_state(tsk, TASK_RUNNING);
688 down_read(&mm->mmap_sem);
689 }
690 atomic_inc(&mm->mm_count);
691 BUG_ON(mm != tsk->active_mm);
692 /* more a memory barrier than a real lock */
693 task_lock(tsk);
694 tsk->mm = NULL;
695 up_read(&mm->mmap_sem);
696 enter_lazy_tlb(mm, current);
697 task_unlock(tsk);
698 mm_update_next_owner(mm);
699 mmput(mm);
700}
701
702/*
703 * When we die, we re-parent all our children, and try to:
704 * 1. give them to another thread in our thread group, if such a member exists
705 * 2. give it to the first ancestor process which prctl'd itself as a
706 * child_subreaper for its children (like a service manager)
707 * 3. give it to the init process (PID 1) in our pid namespace
708 */
709static struct task_struct *find_new_reaper(struct task_struct *father)
710 __releases(&tasklist_lock)
711 __acquires(&tasklist_lock)
712{
713 struct pid_namespace *pid_ns = task_active_pid_ns(father);
714 struct task_struct *thread;
715
716 thread = father;
717 while_each_thread(father, thread) {
718 if (thread->flags & PF_EXITING)
719 continue;
720 if (unlikely(pid_ns->child_reaper == father))
721 pid_ns->child_reaper = thread;
722 return thread;
723 }
724
725 if (unlikely(pid_ns->child_reaper == father)) {
726 write_unlock_irq(&tasklist_lock);
727 if (unlikely(pid_ns == &init_pid_ns)) {
728 panic("Attempted to kill init! exitcode=0x%08x\n",
729 father->signal->group_exit_code ?:
730 father->exit_code);
731 }
732
733 zap_pid_ns_processes(pid_ns);
734 write_lock_irq(&tasklist_lock);
735 } else if (father->signal->has_child_subreaper) {
736 struct task_struct *reaper;
737
738 /*
739 * Find the first ancestor marked as child_subreaper.
740 * Note that the code below checks same_thread_group(reaper,
741 * pid_ns->child_reaper). This is what we need to DTRT in a
742 * PID namespace. However we still need the check above, see
743 * http://marc.info/?l=linux-kernel&m=131385460420380
744 */
745 for (reaper = father->real_parent;
746 reaper != &init_task;
747 reaper = reaper->real_parent) {
748 if (same_thread_group(reaper, pid_ns->child_reaper))
749 break;
750 if (!reaper->signal->is_child_subreaper)
751 continue;
752 thread = reaper;
753 do {
754 if (!(thread->flags & PF_EXITING))
755 return reaper;
756 } while_each_thread(reaper, thread);
757 }
758 }
759
760 return pid_ns->child_reaper;
761}
762
763/*
764* Any that need to be release_task'd are put on the @dead list.
765 */
766static void reparent_leader(struct task_struct *father, struct task_struct *p,
767 struct list_head *dead)
768{
769 list_move_tail(&p->sibling, &p->real_parent->children);
770
771 if (p->exit_state == EXIT_DEAD)
772 return;
773 /*
774 * If this is a threaded reparent there is no need to
775 * notify anyone anything has happened.
776 */
777 if (same_thread_group(p->real_parent, father))
778 return;
779
780 /* We don't want people slaying init. */
781 p->exit_signal = SIGCHLD;
782
783 /* If it has exited notify the new parent about this child's death. */
784 if (!p->ptrace &&
785 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
786 if (do_notify_parent(p, p->exit_signal)) {
787 p->exit_state = EXIT_DEAD;
788 list_move_tail(&p->sibling, dead);
789 }
790 }
791
792 kill_orphaned_pgrp(p, father);
793}
794
795static void forget_original_parent(struct task_struct *father)
796{
797 struct task_struct *p, *n, *reaper;
798 LIST_HEAD(dead_children);
799
800 write_lock_irq(&tasklist_lock);
801 /*
802 * Note that exit_ptrace() and find_new_reaper() might
803 * drop tasklist_lock and reacquire it.
804 */
805 exit_ptrace(father);
806 reaper = find_new_reaper(father);
807
808 list_for_each_entry_safe(p, n, &father->children, sibling) {
809 struct task_struct *t = p;
810 do {
811 t->real_parent = reaper;
812 if (t->parent == father) {
813 BUG_ON(t->ptrace);
814 t->parent = t->real_parent;
815 }
816 if (t->pdeath_signal)
817 group_send_sig_info(t->pdeath_signal,
818 SEND_SIG_NOINFO, t);
819 } while_each_thread(p, t);
820 reparent_leader(father, p, &dead_children);
821 }
822 write_unlock_irq(&tasklist_lock);
823
824 BUG_ON(!list_empty(&father->children));
825
826 list_for_each_entry_safe(p, n, &dead_children, sibling) {
827 list_del_init(&p->sibling);
828 release_task(p);
829 }
830}
831
832/*
833 * Send signals to all our closest relatives so that they know
834 * to properly mourn us..
835 */
836static void exit_notify(struct task_struct *tsk, int group_dead)
837{
838 bool autoreap;
839
840 /*
841 * This does two things:
842 *
843 * A. Make init inherit all the child processes
844 * B. Check to see if any process groups have become orphaned
845 * as a result of our exiting, and if they have any stopped
846 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
847 */
848 forget_original_parent(tsk);
849 exit_task_namespaces(tsk);
850
851 write_lock_irq(&tasklist_lock);
852 if (group_dead)
853 kill_orphaned_pgrp(tsk->group_leader, NULL);
854
855 if (unlikely(tsk->ptrace)) {
856 int sig = thread_group_leader(tsk) &&
857 thread_group_empty(tsk) &&
858 !ptrace_reparented(tsk) ?
859 tsk->exit_signal : SIGCHLD;
860 autoreap = do_notify_parent(tsk, sig);
861 } else if (thread_group_leader(tsk)) {
862 autoreap = thread_group_empty(tsk) &&
863 do_notify_parent(tsk, tsk->exit_signal);
864 } else {
865 autoreap = true;
866 }
867
868 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
869
870 /* mt-exec, de_thread() is waiting for group leader */
871 if (unlikely(tsk->signal->notify_count < 0))
872 wake_up_process(tsk->signal->group_exit_task);
873 write_unlock_irq(&tasklist_lock);
874
875 /* If the process is dead, release it - nobody will wait for it */
876 if (autoreap)
877 release_task(tsk);
878}
879
880#ifdef CONFIG_DEBUG_STACK_USAGE
881static void check_stack_usage(void)
882{
883 static DEFINE_SPINLOCK(low_water_lock);
884 static int lowest_to_date = THREAD_SIZE;
885 unsigned long free;
886
887 free = stack_not_used(current);
888
889 if (free >= lowest_to_date)
890 return;
891
892 spin_lock(&low_water_lock);
893 if (free < lowest_to_date) {
894 printk(KERN_WARNING "%s (%d) used greatest stack depth: "
895 "%lu bytes left\n",
896 current->comm, task_pid_nr(current), free);
897 lowest_to_date = free;
898 }
899 spin_unlock(&low_water_lock);
900}
901#else
902static inline void check_stack_usage(void) {}
903#endif
904
905void do_exit(long code)
906{
907 struct task_struct *tsk = current;
908 int group_dead;
909
910 profile_task_exit(tsk);
911
912 WARN_ON(blk_needs_flush_plug(tsk));
913
914 if (unlikely(in_interrupt()))
915 panic("Aiee, killing interrupt handler!");
916 if (unlikely(!tsk->pid))
917 panic("Attempted to kill the idle task!");
918
919 /*
920 * If do_exit is called because this processes oopsed, it's possible
921 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
922 * continuing. Amongst other possible reasons, this is to prevent
923 * mm_release()->clear_child_tid() from writing to a user-controlled
924 * kernel address.
925 */
926 set_fs(USER_DS);
927
928 ptrace_event(PTRACE_EVENT_EXIT, code);
929
930 validate_creds_for_do_exit(tsk);
931
932 /*
933 * We're taking recursive faults here in do_exit. Safest is to just
934 * leave this task alone and wait for reboot.
935 */
936 if (unlikely(tsk->flags & PF_EXITING)) {
937 printk(KERN_ALERT
938 "Fixing recursive fault but reboot is needed!\n");
939 /*
940 * We can do this unlocked here. The futex code uses
941 * this flag just to verify whether the pi state
942 * cleanup has been done or not. In the worst case it
943 * loops once more. We pretend that the cleanup was
944 * done as there is no way to return. Either the
945 * OWNER_DIED bit is set by now or we push the blocked
946 * task into the wait for ever nirwana as well.
947 */
948 tsk->flags |= PF_EXITPIDONE;
949 set_current_state(TASK_UNINTERRUPTIBLE);
950 schedule();
951 }
952
953 exit_signals(tsk); /* sets PF_EXITING */
954 /*
955 * tsk->flags are checked in the futex code to protect against
956 * an exiting task cleaning up the robust pi futexes, and in
957 * task_work_add() to avoid the race with exit_task_work().
958 */
959 smp_mb();
960 raw_spin_unlock_wait(&tsk->pi_lock);
961
962 exit_task_work(tsk);
963
964 if (unlikely(in_atomic()))
965 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
966 current->comm, task_pid_nr(current),
967 preempt_count());
968
969 acct_update_integrals(tsk);
970 /* sync mm's RSS info before statistics gathering */
971 if (tsk->mm)
972 sync_mm_rss(tsk->mm);
973 group_dead = atomic_dec_and_test(&tsk->signal->live);
974 if (group_dead) {
975 hrtimer_cancel(&tsk->signal->real_timer);
976 exit_itimers(tsk->signal);
977 if (tsk->mm)
978 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
979 }
980 acct_collect(code, group_dead);
981 if (group_dead)
982 tty_audit_exit();
983 audit_free(tsk);
984
985 tsk->exit_code = code;
986 taskstats_exit(tsk, group_dead);
987
988 exit_mm(tsk);
989
990 if (group_dead)
991 acct_process();
992 trace_sched_process_exit(tsk);
993
994 exit_sem(tsk);
995 exit_shm(tsk);
996 exit_files(tsk);
997 exit_fs(tsk);
998 check_stack_usage();
999 exit_thread();
1000
1001 /*
1002 * Flush inherited counters to the parent - before the parent
1003 * gets woken up by child-exit notifications.
1004 *
1005 * because of cgroup mode, must be called before cgroup_exit()
1006 */
1007 perf_event_exit_task(tsk);
1008
1009 cgroup_exit(tsk, 1);
1010
1011 if (group_dead)
1012 disassociate_ctty(1);
1013
1014 module_put(task_thread_info(tsk)->exec_domain->module);
1015
1016 proc_exit_connector(tsk);
1017
1018 /*
1019 * FIXME: do that only when needed, using sched_exit tracepoint
1020 */
1021 ptrace_put_breakpoints(tsk);
1022
1023 exit_notify(tsk, group_dead);
1024#ifdef CONFIG_NUMA
1025 task_lock(tsk);
1026 mpol_put(tsk->mempolicy);
1027 tsk->mempolicy = NULL;
1028 task_unlock(tsk);
1029#endif
1030#ifdef CONFIG_FUTEX
1031 if (unlikely(current->pi_state_cache))
1032 kfree(current->pi_state_cache);
1033#endif
1034 /*
1035 * Make sure we are holding no locks:
1036 */
1037 debug_check_no_locks_held(tsk);
1038 /*
1039 * We can do this unlocked here. The futex code uses this flag
1040 * just to verify whether the pi state cleanup has been done
1041 * or not. In the worst case it loops once more.
1042 */
1043 tsk->flags |= PF_EXITPIDONE;
1044
1045 if (tsk->io_context)
1046 exit_io_context(tsk);
1047
1048 if (tsk->splice_pipe)
1049 __free_pipe_info(tsk->splice_pipe);
1050
1051 validate_creds_for_do_exit(tsk);
1052
1053 preempt_disable();
1054 if (tsk->nr_dirtied)
1055 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
1056 exit_rcu();
1057
1058 /*
1059 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
1060 * when the following two conditions become true.
1061 * - There is race condition of mmap_sem (It is acquired by
1062 * exit_mm()), and
1063 * - SMI occurs before setting TASK_RUNINNG.
1064 * (or hypervisor of virtual machine switches to other guest)
1065 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
1066 *
1067 * To avoid it, we have to wait for releasing tsk->pi_lock which
1068 * is held by try_to_wake_up()
1069 */
1070 smp_mb();
1071 raw_spin_unlock_wait(&tsk->pi_lock);
1072
1073 /* causes final put_task_struct in finish_task_switch(). */
1074 tsk->state = TASK_DEAD;
1075 tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */
1076 schedule();
1077 BUG();
1078 /* Avoid "noreturn function does return". */
1079 for (;;)
1080 cpu_relax(); /* For when BUG is null */
1081}
1082
1083EXPORT_SYMBOL_GPL(do_exit);
1084
1085void complete_and_exit(struct completion *comp, long code)
1086{
1087 if (comp)
1088 complete(comp);
1089
1090 do_exit(code);
1091}
1092
1093EXPORT_SYMBOL(complete_and_exit);
1094
1095SYSCALL_DEFINE1(exit, int, error_code)
1096{
1097 do_exit((error_code&0xff)<<8);
1098}
1099
1100/*
1101 * Take down every thread in the group. This is called by fatal signals
1102 * as well as by sys_exit_group (below).
1103 */
1104void
1105do_group_exit(int exit_code)
1106{
1107 struct signal_struct *sig = current->signal;
1108
1109 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1110
1111 if (signal_group_exit(sig))
1112 exit_code = sig->group_exit_code;
1113 else if (!thread_group_empty(current)) {
1114 struct sighand_struct *const sighand = current->sighand;
1115 spin_lock_irq(&sighand->siglock);
1116 if (signal_group_exit(sig))
1117 /* Another thread got here before we took the lock. */
1118 exit_code = sig->group_exit_code;
1119 else {
1120 sig->group_exit_code = exit_code;
1121 sig->flags = SIGNAL_GROUP_EXIT;
1122 zap_other_threads(current);
1123 }
1124 spin_unlock_irq(&sighand->siglock);
1125 }
1126
1127 do_exit(exit_code);
1128 /* NOTREACHED */
1129}
1130
1131/*
1132 * this kills every thread in the thread group. Note that any externally
1133 * wait4()-ing process will get the correct exit code - even if this
1134 * thread is not the thread group leader.
1135 */
1136SYSCALL_DEFINE1(exit_group, int, error_code)
1137{
1138 do_group_exit((error_code & 0xff) << 8);
1139 /* NOTREACHED */
1140 return 0;
1141}
1142
1143struct wait_opts {
1144 enum pid_type wo_type;
1145 int wo_flags;
1146 struct pid *wo_pid;
1147
1148 struct siginfo __user *wo_info;
1149 int __user *wo_stat;
1150 struct rusage __user *wo_rusage;
1151
1152 wait_queue_t child_wait;
1153 int notask_error;
1154};
1155
1156static inline
1157struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
1158{
1159 if (type != PIDTYPE_PID)
1160 task = task->group_leader;
1161 return task->pids[type].pid;
1162}
1163
1164static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
1165{
1166 return wo->wo_type == PIDTYPE_MAX ||
1167 task_pid_type(p, wo->wo_type) == wo->wo_pid;
1168}
1169
1170static int eligible_child(struct wait_opts *wo, struct task_struct *p)
1171{
1172 if (!eligible_pid(wo, p))
1173 return 0;
1174 /* Wait for all children (clone and not) if __WALL is set;
1175 * otherwise, wait for clone children *only* if __WCLONE is
1176 * set; otherwise, wait for non-clone children *only*. (Note:
1177 * A "clone" child here is one that reports to its parent
1178 * using a signal other than SIGCHLD.) */
1179 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
1180 && !(wo->wo_flags & __WALL))
1181 return 0;
1182
1183 return 1;
1184}
1185
1186static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
1187 pid_t pid, uid_t uid, int why, int status)
1188{
1189 struct siginfo __user *infop;
1190 int retval = wo->wo_rusage
1191 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1192
1193 put_task_struct(p);
1194 infop = wo->wo_info;
1195 if (infop) {
1196 if (!retval)
1197 retval = put_user(SIGCHLD, &infop->si_signo);
1198 if (!retval)
1199 retval = put_user(0, &infop->si_errno);
1200 if (!retval)
1201 retval = put_user((short)why, &infop->si_code);
1202 if (!retval)
1203 retval = put_user(pid, &infop->si_pid);
1204 if (!retval)
1205 retval = put_user(uid, &infop->si_uid);
1206 if (!retval)
1207 retval = put_user(status, &infop->si_status);
1208 }
1209 if (!retval)
1210 retval = pid;
1211 return retval;
1212}
1213
1214/*
1215 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1216 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1217 * the lock and this task is uninteresting. If we return nonzero, we have
1218 * released the lock and the system call should return.
1219 */
1220static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1221{
1222 unsigned long state;
1223 int retval, status, traced;
1224 pid_t pid = task_pid_vnr(p);
1225 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1226 struct siginfo __user *infop;
1227
1228 if (!likely(wo->wo_flags & WEXITED))
1229 return 0;
1230
1231 if (unlikely(wo->wo_flags & WNOWAIT)) {
1232 int exit_code = p->exit_code;
1233 int why;
1234
1235 get_task_struct(p);
1236 read_unlock(&tasklist_lock);
1237 if ((exit_code & 0x7f) == 0) {
1238 why = CLD_EXITED;
1239 status = exit_code >> 8;
1240 } else {
1241 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1242 status = exit_code & 0x7f;
1243 }
1244 return wait_noreap_copyout(wo, p, pid, uid, why, status);
1245 }
1246
1247 /*
1248 * Try to move the task's state to DEAD
1249 * only one thread is allowed to do this:
1250 */
1251 state = xchg(&p->exit_state, EXIT_DEAD);
1252 if (state != EXIT_ZOMBIE) {
1253 BUG_ON(state != EXIT_DEAD);
1254 return 0;
1255 }
1256
1257 traced = ptrace_reparented(p);
1258 /*
1259 * It can be ptraced but not reparented, check
1260 * thread_group_leader() to filter out sub-threads.
1261 */
1262 if (likely(!traced) && thread_group_leader(p)) {
1263 struct signal_struct *psig;
1264 struct signal_struct *sig;
1265 unsigned long maxrss;
1266 cputime_t tgutime, tgstime;
1267
1268 /*
1269 * The resource counters for the group leader are in its
1270 * own task_struct. Those for dead threads in the group
1271 * are in its signal_struct, as are those for the child
1272 * processes it has previously reaped. All these
1273 * accumulate in the parent's signal_struct c* fields.
1274 *
1275 * We don't bother to take a lock here to protect these
1276 * p->signal fields, because they are only touched by
1277 * __exit_signal, which runs with tasklist_lock
1278 * write-locked anyway, and so is excluded here. We do
1279 * need to protect the access to parent->signal fields,
1280 * as other threads in the parent group can be right
1281 * here reaping other children at the same time.
1282 *
1283 * We use thread_group_times() to get times for the thread
1284 * group, which consolidates times for all threads in the
1285 * group including the group leader.
1286 */
1287 thread_group_times(p, &tgutime, &tgstime);
1288 spin_lock_irq(&p->real_parent->sighand->siglock);
1289 psig = p->real_parent->signal;
1290 sig = p->signal;
1291 psig->cutime += tgutime + sig->cutime;
1292 psig->cstime += tgstime + sig->cstime;
1293 psig->cgtime += p->gtime + sig->gtime + sig->cgtime;
1294 psig->cmin_flt +=
1295 p->min_flt + sig->min_flt + sig->cmin_flt;
1296 psig->cmaj_flt +=
1297 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1298 psig->cnvcsw +=
1299 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1300 psig->cnivcsw +=
1301 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1302 psig->cinblock +=
1303 task_io_get_inblock(p) +
1304 sig->inblock + sig->cinblock;
1305 psig->coublock +=
1306 task_io_get_oublock(p) +
1307 sig->oublock + sig->coublock;
1308 maxrss = max(sig->maxrss, sig->cmaxrss);
1309 if (psig->cmaxrss < maxrss)
1310 psig->cmaxrss = maxrss;
1311 task_io_accounting_add(&psig->ioac, &p->ioac);
1312 task_io_accounting_add(&psig->ioac, &sig->ioac);
1313 spin_unlock_irq(&p->real_parent->sighand->siglock);
1314 }
1315
1316 /*
1317 * Now we are sure this task is interesting, and no other
1318 * thread can reap it because we set its state to EXIT_DEAD.
1319 */
1320 read_unlock(&tasklist_lock);
1321
1322 retval = wo->wo_rusage
1323 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1324 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1325 ? p->signal->group_exit_code : p->exit_code;
1326 if (!retval && wo->wo_stat)
1327 retval = put_user(status, wo->wo_stat);
1328
1329 infop = wo->wo_info;
1330 if (!retval && infop)
1331 retval = put_user(SIGCHLD, &infop->si_signo);
1332 if (!retval && infop)
1333 retval = put_user(0, &infop->si_errno);
1334 if (!retval && infop) {
1335 int why;
1336
1337 if ((status & 0x7f) == 0) {
1338 why = CLD_EXITED;
1339 status >>= 8;
1340 } else {
1341 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1342 status &= 0x7f;
1343 }
1344 retval = put_user((short)why, &infop->si_code);
1345 if (!retval)
1346 retval = put_user(status, &infop->si_status);
1347 }
1348 if (!retval && infop)
1349 retval = put_user(pid, &infop->si_pid);
1350 if (!retval && infop)
1351 retval = put_user(uid, &infop->si_uid);
1352 if (!retval)
1353 retval = pid;
1354
1355 if (traced) {
1356 write_lock_irq(&tasklist_lock);
1357 /* We dropped tasklist, ptracer could die and untrace */
1358 ptrace_unlink(p);
1359 /*
1360 * If this is not a sub-thread, notify the parent.
1361 * If parent wants a zombie, don't release it now.
1362 */
1363 if (thread_group_leader(p) &&
1364 !do_notify_parent(p, p->exit_signal)) {
1365 p->exit_state = EXIT_ZOMBIE;
1366 p = NULL;
1367 }
1368 write_unlock_irq(&tasklist_lock);
1369 }
1370 if (p != NULL)
1371 release_task(p);
1372
1373 return retval;
1374}
1375
1376static int *task_stopped_code(struct task_struct *p, bool ptrace)
1377{
1378 if (ptrace) {
1379 if (task_is_stopped_or_traced(p) &&
1380 !(p->jobctl & JOBCTL_LISTENING))
1381 return &p->exit_code;
1382 } else {
1383 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1384 return &p->signal->group_exit_code;
1385 }
1386 return NULL;
1387}
1388
1389/**
1390 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1391 * @wo: wait options
1392 * @ptrace: is the wait for ptrace
1393 * @p: task to wait for
1394 *
1395 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1396 *
1397 * CONTEXT:
1398 * read_lock(&tasklist_lock), which is released if return value is
1399 * non-zero. Also, grabs and releases @p->sighand->siglock.
1400 *
1401 * RETURNS:
1402 * 0 if wait condition didn't exist and search for other wait conditions
1403 * should continue. Non-zero return, -errno on failure and @p's pid on
1404 * success, implies that tasklist_lock is released and wait condition
1405 * search should terminate.
1406 */
1407static int wait_task_stopped(struct wait_opts *wo,
1408 int ptrace, struct task_struct *p)
1409{
1410 struct siginfo __user *infop;
1411 int retval, exit_code, *p_code, why;
1412 uid_t uid = 0; /* unneeded, required by compiler */
1413 pid_t pid;
1414
1415 /*
1416 * Traditionally we see ptrace'd stopped tasks regardless of options.
1417 */
1418 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1419 return 0;
1420
1421 if (!task_stopped_code(p, ptrace))
1422 return 0;
1423
1424 exit_code = 0;
1425 spin_lock_irq(&p->sighand->siglock);
1426
1427 p_code = task_stopped_code(p, ptrace);
1428 if (unlikely(!p_code))
1429 goto unlock_sig;
1430
1431 exit_code = *p_code;
1432 if (!exit_code)
1433 goto unlock_sig;
1434
1435 if (!unlikely(wo->wo_flags & WNOWAIT))
1436 *p_code = 0;
1437
1438 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1439unlock_sig:
1440 spin_unlock_irq(&p->sighand->siglock);
1441 if (!exit_code)
1442 return 0;
1443
1444 /*
1445 * Now we are pretty sure this task is interesting.
1446 * Make sure it doesn't get reaped out from under us while we
1447 * give up the lock and then examine it below. We don't want to
1448 * keep holding onto the tasklist_lock while we call getrusage and
1449 * possibly take page faults for user memory.
1450 */
1451 get_task_struct(p);
1452 pid = task_pid_vnr(p);
1453 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1454 read_unlock(&tasklist_lock);
1455
1456 if (unlikely(wo->wo_flags & WNOWAIT))
1457 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
1458
1459 retval = wo->wo_rusage
1460 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1461 if (!retval && wo->wo_stat)
1462 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
1463
1464 infop = wo->wo_info;
1465 if (!retval && infop)
1466 retval = put_user(SIGCHLD, &infop->si_signo);
1467 if (!retval && infop)
1468 retval = put_user(0, &infop->si_errno);
1469 if (!retval && infop)
1470 retval = put_user((short)why, &infop->si_code);
1471 if (!retval && infop)
1472 retval = put_user(exit_code, &infop->si_status);
1473 if (!retval && infop)
1474 retval = put_user(pid, &infop->si_pid);
1475 if (!retval && infop)
1476 retval = put_user(uid, &infop->si_uid);
1477 if (!retval)
1478 retval = pid;
1479 put_task_struct(p);
1480
1481 BUG_ON(!retval);
1482 return retval;
1483}
1484
1485/*
1486 * Handle do_wait work for one task in a live, non-stopped state.
1487 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1488 * the lock and this task is uninteresting. If we return nonzero, we have
1489 * released the lock and the system call should return.
1490 */
1491static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1492{
1493 int retval;
1494 pid_t pid;
1495 uid_t uid;
1496
1497 if (!unlikely(wo->wo_flags & WCONTINUED))
1498 return 0;
1499
1500 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1501 return 0;
1502
1503 spin_lock_irq(&p->sighand->siglock);
1504 /* Re-check with the lock held. */
1505 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1506 spin_unlock_irq(&p->sighand->siglock);
1507 return 0;
1508 }
1509 if (!unlikely(wo->wo_flags & WNOWAIT))
1510 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1511 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1512 spin_unlock_irq(&p->sighand->siglock);
1513
1514 pid = task_pid_vnr(p);
1515 get_task_struct(p);
1516 read_unlock(&tasklist_lock);
1517
1518 if (!wo->wo_info) {
1519 retval = wo->wo_rusage
1520 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1521 put_task_struct(p);
1522 if (!retval && wo->wo_stat)
1523 retval = put_user(0xffff, wo->wo_stat);
1524 if (!retval)
1525 retval = pid;
1526 } else {
1527 retval = wait_noreap_copyout(wo, p, pid, uid,
1528 CLD_CONTINUED, SIGCONT);
1529 BUG_ON(retval == 0);
1530 }
1531
1532 return retval;
1533}
1534
1535/*
1536 * Consider @p for a wait by @parent.
1537 *
1538 * -ECHILD should be in ->notask_error before the first call.
1539 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1540 * Returns zero if the search for a child should continue;
1541 * then ->notask_error is 0 if @p is an eligible child,
1542 * or another error from security_task_wait(), or still -ECHILD.
1543 */
1544static int wait_consider_task(struct wait_opts *wo, int ptrace,
1545 struct task_struct *p)
1546{
1547 int ret = eligible_child(wo, p);
1548 if (!ret)
1549 return ret;
1550
1551 ret = security_task_wait(p);
1552 if (unlikely(ret < 0)) {
1553 /*
1554 * If we have not yet seen any eligible child,
1555 * then let this error code replace -ECHILD.
1556 * A permission error will give the user a clue
1557 * to look for security policy problems, rather
1558 * than for mysterious wait bugs.
1559 */
1560 if (wo->notask_error)
1561 wo->notask_error = ret;
1562 return 0;
1563 }
1564
1565 /* dead body doesn't have much to contribute */
1566 if (unlikely(p->exit_state == EXIT_DEAD)) {
1567 /*
1568 * But do not ignore this task until the tracer does
1569 * wait_task_zombie()->do_notify_parent().
1570 */
1571 if (likely(!ptrace) && unlikely(ptrace_reparented(p)))
1572 wo->notask_error = 0;
1573 return 0;
1574 }
1575
1576 /* slay zombie? */
1577 if (p->exit_state == EXIT_ZOMBIE) {
1578 /*
1579 * A zombie ptracee is only visible to its ptracer.
1580 * Notification and reaping will be cascaded to the real
1581 * parent when the ptracer detaches.
1582 */
1583 if (likely(!ptrace) && unlikely(p->ptrace)) {
1584 /* it will become visible, clear notask_error */
1585 wo->notask_error = 0;
1586 return 0;
1587 }
1588
1589 /* we don't reap group leaders with subthreads */
1590 if (!delay_group_leader(p))
1591 return wait_task_zombie(wo, p);
1592
1593 /*
1594 * Allow access to stopped/continued state via zombie by
1595 * falling through. Clearing of notask_error is complex.
1596 *
1597 * When !@ptrace:
1598 *
1599 * If WEXITED is set, notask_error should naturally be
1600 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1601 * so, if there are live subthreads, there are events to
1602 * wait for. If all subthreads are dead, it's still safe
1603 * to clear - this function will be called again in finite
1604 * amount time once all the subthreads are released and
1605 * will then return without clearing.
1606 *
1607 * When @ptrace:
1608 *
1609 * Stopped state is per-task and thus can't change once the
1610 * target task dies. Only continued and exited can happen.
1611 * Clear notask_error if WCONTINUED | WEXITED.
1612 */
1613 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1614 wo->notask_error = 0;
1615 } else {
1616 /*
1617 * If @p is ptraced by a task in its real parent's group,
1618 * hide group stop/continued state when looking at @p as
1619 * the real parent; otherwise, a single stop can be
1620 * reported twice as group and ptrace stops.
1621 *
1622 * If a ptracer wants to distinguish the two events for its
1623 * own children, it should create a separate process which
1624 * takes the role of real parent.
1625 */
1626 if (likely(!ptrace) && p->ptrace && !ptrace_reparented(p))
1627 return 0;
1628
1629 /*
1630 * @p is alive and it's gonna stop, continue or exit, so
1631 * there always is something to wait for.
1632 */
1633 wo->notask_error = 0;
1634 }
1635
1636 /*
1637 * Wait for stopped. Depending on @ptrace, different stopped state
1638 * is used and the two don't interact with each other.
1639 */
1640 ret = wait_task_stopped(wo, ptrace, p);
1641 if (ret)
1642 return ret;
1643
1644 /*
1645 * Wait for continued. There's only one continued state and the
1646 * ptracer can consume it which can confuse the real parent. Don't
1647 * use WCONTINUED from ptracer. You don't need or want it.
1648 */
1649 return wait_task_continued(wo, p);
1650}
1651
1652/*
1653 * Do the work of do_wait() for one thread in the group, @tsk.
1654 *
1655 * -ECHILD should be in ->notask_error before the first call.
1656 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1657 * Returns zero if the search for a child should continue; then
1658 * ->notask_error is 0 if there were any eligible children,
1659 * or another error from security_task_wait(), or still -ECHILD.
1660 */
1661static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1662{
1663 struct task_struct *p;
1664
1665 list_for_each_entry(p, &tsk->children, sibling) {
1666 int ret = wait_consider_task(wo, 0, p);
1667 if (ret)
1668 return ret;
1669 }
1670
1671 return 0;
1672}
1673
1674static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1675{
1676 struct task_struct *p;
1677
1678 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1679 int ret = wait_consider_task(wo, 1, p);
1680 if (ret)
1681 return ret;
1682 }
1683
1684 return 0;
1685}
1686
1687static int child_wait_callback(wait_queue_t *wait, unsigned mode,
1688 int sync, void *key)
1689{
1690 struct wait_opts *wo = container_of(wait, struct wait_opts,
1691 child_wait);
1692 struct task_struct *p = key;
1693
1694 if (!eligible_pid(wo, p))
1695 return 0;
1696
1697 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1698 return 0;
1699
1700 return default_wake_function(wait, mode, sync, key);
1701}
1702
1703void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1704{
1705 __wake_up_sync_key(&parent->signal->wait_chldexit,
1706 TASK_INTERRUPTIBLE, 1, p);
1707}
1708
1709static long do_wait(struct wait_opts *wo)
1710{
1711 struct task_struct *tsk;
1712 int retval;
1713
1714 trace_sched_process_wait(wo->wo_pid);
1715
1716 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1717 wo->child_wait.private = current;
1718 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1719repeat:
1720 /*
1721 * If there is nothing that can match our critiera just get out.
1722 * We will clear ->notask_error to zero if we see any child that
1723 * might later match our criteria, even if we are not able to reap
1724 * it yet.
1725 */
1726 wo->notask_error = -ECHILD;
1727 if ((wo->wo_type < PIDTYPE_MAX) &&
1728 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1729 goto notask;
1730
1731 set_current_state(TASK_INTERRUPTIBLE);
1732 read_lock(&tasklist_lock);
1733 tsk = current;
1734 do {
1735 retval = do_wait_thread(wo, tsk);
1736 if (retval)
1737 goto end;
1738
1739 retval = ptrace_do_wait(wo, tsk);
1740 if (retval)
1741 goto end;
1742
1743 if (wo->wo_flags & __WNOTHREAD)
1744 break;
1745 } while_each_thread(current, tsk);
1746 read_unlock(&tasklist_lock);
1747
1748notask:
1749 retval = wo->notask_error;
1750 if (!retval && !(wo->wo_flags & WNOHANG)) {
1751 retval = -ERESTARTSYS;
1752 if (!signal_pending(current)) {
1753 schedule();
1754 goto repeat;
1755 }
1756 }
1757end:
1758 __set_current_state(TASK_RUNNING);
1759 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1760 return retval;
1761}
1762
1763SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1764 infop, int, options, struct rusage __user *, ru)
1765{
1766 struct wait_opts wo;
1767 struct pid *pid = NULL;
1768 enum pid_type type;
1769 long ret;
1770
1771 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1772 return -EINVAL;
1773 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1774 return -EINVAL;
1775
1776 switch (which) {
1777 case P_ALL:
1778 type = PIDTYPE_MAX;
1779 break;
1780 case P_PID:
1781 type = PIDTYPE_PID;
1782 if (upid <= 0)
1783 return -EINVAL;
1784 break;
1785 case P_PGID:
1786 type = PIDTYPE_PGID;
1787 if (upid <= 0)
1788 return -EINVAL;
1789 break;
1790 default:
1791 return -EINVAL;
1792 }
1793
1794 if (type < PIDTYPE_MAX)
1795 pid = find_get_pid(upid);
1796
1797 wo.wo_type = type;
1798 wo.wo_pid = pid;
1799 wo.wo_flags = options;
1800 wo.wo_info = infop;
1801 wo.wo_stat = NULL;
1802 wo.wo_rusage = ru;
1803 ret = do_wait(&wo);
1804
1805 if (ret > 0) {
1806 ret = 0;
1807 } else if (infop) {
1808 /*
1809 * For a WNOHANG return, clear out all the fields
1810 * we would set so the user can easily tell the
1811 * difference.
1812 */
1813 if (!ret)
1814 ret = put_user(0, &infop->si_signo);
1815 if (!ret)
1816 ret = put_user(0, &infop->si_errno);
1817 if (!ret)
1818 ret = put_user(0, &infop->si_code);
1819 if (!ret)
1820 ret = put_user(0, &infop->si_pid);
1821 if (!ret)
1822 ret = put_user(0, &infop->si_uid);
1823 if (!ret)
1824 ret = put_user(0, &infop->si_status);
1825 }
1826
1827 put_pid(pid);
1828
1829 /* avoid REGPARM breakage on x86: */
1830 asmlinkage_protect(5, ret, which, upid, infop, options, ru);
1831 return ret;
1832}
1833
1834SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1835 int, options, struct rusage __user *, ru)
1836{
1837 struct wait_opts wo;
1838 struct pid *pid = NULL;
1839 enum pid_type type;
1840 long ret;
1841
1842 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1843 __WNOTHREAD|__WCLONE|__WALL))
1844 return -EINVAL;
1845
1846 if (upid == -1)
1847 type = PIDTYPE_MAX;
1848 else if (upid < 0) {
1849 type = PIDTYPE_PGID;
1850 pid = find_get_pid(-upid);
1851 } else if (upid == 0) {
1852 type = PIDTYPE_PGID;
1853 pid = get_task_pid(current, PIDTYPE_PGID);
1854 } else /* upid > 0 */ {
1855 type = PIDTYPE_PID;
1856 pid = find_get_pid(upid);
1857 }
1858
1859 wo.wo_type = type;
1860 wo.wo_pid = pid;
1861 wo.wo_flags = options | WEXITED;
1862 wo.wo_info = NULL;
1863 wo.wo_stat = stat_addr;
1864 wo.wo_rusage = ru;
1865 ret = do_wait(&wo);
1866 put_pid(pid);
1867
1868 /* avoid REGPARM breakage on x86: */
1869 asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
1870 return ret;
1871}
1872
1873#ifdef __ARCH_WANT_SYS_WAITPID
1874
1875/*
1876 * sys_waitpid() remains for compatibility. waitpid() should be
1877 * implemented by calling sys_wait4() from libc.a.
1878 */
1879SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1880{
1881 return sys_wait4(pid, stat_addr, options, NULL);
1882}
1883
1884#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#include <linux/io_uring.h>
67
68#include <linux/uaccess.h>
69#include <asm/unistd.h>
70#include <asm/mmu_context.h>
71
72static void __unhash_process(struct task_struct *p, bool group_dead)
73{
74 nr_threads--;
75 detach_pid(p, PIDTYPE_PID);
76 if (group_dead) {
77 detach_pid(p, PIDTYPE_TGID);
78 detach_pid(p, PIDTYPE_PGID);
79 detach_pid(p, PIDTYPE_SID);
80
81 list_del_rcu(&p->tasks);
82 list_del_init(&p->sibling);
83 __this_cpu_dec(process_counts);
84 }
85 list_del_rcu(&p->thread_group);
86 list_del_rcu(&p->thread_node);
87}
88
89/*
90 * This function expects the tasklist_lock write-locked.
91 */
92static void __exit_signal(struct task_struct *tsk)
93{
94 struct signal_struct *sig = tsk->signal;
95 bool group_dead = thread_group_leader(tsk);
96 struct sighand_struct *sighand;
97 struct tty_struct *tty;
98 u64 utime, stime;
99
100 sighand = rcu_dereference_check(tsk->sighand,
101 lockdep_tasklist_lock_is_held());
102 spin_lock(&sighand->siglock);
103
104#ifdef CONFIG_POSIX_TIMERS
105 posix_cpu_timers_exit(tsk);
106 if (group_dead)
107 posix_cpu_timers_exit_group(tsk);
108#endif
109
110 if (group_dead) {
111 tty = sig->tty;
112 sig->tty = NULL;
113 } else {
114 /*
115 * If there is any task waiting for the group exit
116 * then notify it:
117 */
118 if (sig->notify_count > 0 && !--sig->notify_count)
119 wake_up_process(sig->group_exit_task);
120
121 if (tsk == sig->curr_target)
122 sig->curr_target = next_thread(tsk);
123 }
124
125 add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
126 sizeof(unsigned long long));
127
128 /*
129 * Accumulate here the counters for all threads as they die. We could
130 * skip the group leader because it is the last user of signal_struct,
131 * but we want to avoid the race with thread_group_cputime() which can
132 * see the empty ->thread_head list.
133 */
134 task_cputime(tsk, &utime, &stime);
135 write_seqlock(&sig->stats_lock);
136 sig->utime += utime;
137 sig->stime += stime;
138 sig->gtime += task_gtime(tsk);
139 sig->min_flt += tsk->min_flt;
140 sig->maj_flt += tsk->maj_flt;
141 sig->nvcsw += tsk->nvcsw;
142 sig->nivcsw += tsk->nivcsw;
143 sig->inblock += task_io_get_inblock(tsk);
144 sig->oublock += task_io_get_oublock(tsk);
145 task_io_accounting_add(&sig->ioac, &tsk->ioac);
146 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
147 sig->nr_threads--;
148 __unhash_process(tsk, group_dead);
149 write_sequnlock(&sig->stats_lock);
150
151 /*
152 * Do this under ->siglock, we can race with another thread
153 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
154 */
155 flush_sigqueue(&tsk->pending);
156 tsk->sighand = NULL;
157 spin_unlock(&sighand->siglock);
158
159 __cleanup_sighand(sighand);
160 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
161 if (group_dead) {
162 flush_sigqueue(&sig->shared_pending);
163 tty_kref_put(tty);
164 }
165}
166
167static void delayed_put_task_struct(struct rcu_head *rhp)
168{
169 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
170
171 perf_event_delayed_put(tsk);
172 trace_sched_process_free(tsk);
173 put_task_struct(tsk);
174}
175
176void put_task_struct_rcu_user(struct task_struct *task)
177{
178 if (refcount_dec_and_test(&task->rcu_users))
179 call_rcu(&task->rcu, delayed_put_task_struct);
180}
181
182void release_task(struct task_struct *p)
183{
184 struct task_struct *leader;
185 struct pid *thread_pid;
186 int zap_leader;
187repeat:
188 /* don't need to get the RCU readlock here - the process is dead and
189 * can't be modifying its own credentials. But shut RCU-lockdep up */
190 rcu_read_lock();
191 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
192 rcu_read_unlock();
193
194 cgroup_release(p);
195
196 write_lock_irq(&tasklist_lock);
197 ptrace_release_task(p);
198 thread_pid = get_pid(p->thread_pid);
199 __exit_signal(p);
200
201 /*
202 * If we are the last non-leader member of the thread
203 * group, and the leader is zombie, then notify the
204 * group leader's parent process. (if it wants notification.)
205 */
206 zap_leader = 0;
207 leader = p->group_leader;
208 if (leader != p && thread_group_empty(leader)
209 && leader->exit_state == EXIT_ZOMBIE) {
210 /*
211 * If we were the last child thread and the leader has
212 * exited already, and the leader's parent ignores SIGCHLD,
213 * then we are the one who should release the leader.
214 */
215 zap_leader = do_notify_parent(leader, leader->exit_signal);
216 if (zap_leader)
217 leader->exit_state = EXIT_DEAD;
218 }
219
220 write_unlock_irq(&tasklist_lock);
221 seccomp_filter_release(p);
222 proc_flush_pid(thread_pid);
223 put_pid(thread_pid);
224 release_thread(p);
225 put_task_struct_rcu_user(p);
226
227 p = leader;
228 if (unlikely(zap_leader))
229 goto repeat;
230}
231
232int rcuwait_wake_up(struct rcuwait *w)
233{
234 int ret = 0;
235 struct task_struct *task;
236
237 rcu_read_lock();
238
239 /*
240 * Order condition vs @task, such that everything prior to the load
241 * of @task is visible. This is the condition as to why the user called
242 * rcuwait_wake() in the first place. Pairs with set_current_state()
243 * barrier (A) in rcuwait_wait_event().
244 *
245 * WAIT WAKE
246 * [S] tsk = current [S] cond = true
247 * MB (A) MB (B)
248 * [L] cond [L] tsk
249 */
250 smp_mb(); /* (B) */
251
252 task = rcu_dereference(w->task);
253 if (task)
254 ret = wake_up_process(task);
255 rcu_read_unlock();
256
257 return ret;
258}
259EXPORT_SYMBOL_GPL(rcuwait_wake_up);
260
261/*
262 * Determine if a process group is "orphaned", according to the POSIX
263 * definition in 2.2.2.52. Orphaned process groups are not to be affected
264 * by terminal-generated stop signals. Newly orphaned process groups are
265 * to receive a SIGHUP and a SIGCONT.
266 *
267 * "I ask you, have you ever known what it is to be an orphan?"
268 */
269static int will_become_orphaned_pgrp(struct pid *pgrp,
270 struct task_struct *ignored_task)
271{
272 struct task_struct *p;
273
274 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
275 if ((p == ignored_task) ||
276 (p->exit_state && thread_group_empty(p)) ||
277 is_global_init(p->real_parent))
278 continue;
279
280 if (task_pgrp(p->real_parent) != pgrp &&
281 task_session(p->real_parent) == task_session(p))
282 return 0;
283 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
284
285 return 1;
286}
287
288int is_current_pgrp_orphaned(void)
289{
290 int retval;
291
292 read_lock(&tasklist_lock);
293 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
294 read_unlock(&tasklist_lock);
295
296 return retval;
297}
298
299static bool has_stopped_jobs(struct pid *pgrp)
300{
301 struct task_struct *p;
302
303 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
304 if (p->signal->flags & SIGNAL_STOP_STOPPED)
305 return true;
306 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
307
308 return false;
309}
310
311/*
312 * Check to see if any process groups have become orphaned as
313 * a result of our exiting, and if they have any stopped jobs,
314 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
315 */
316static void
317kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
318{
319 struct pid *pgrp = task_pgrp(tsk);
320 struct task_struct *ignored_task = tsk;
321
322 if (!parent)
323 /* exit: our father is in a different pgrp than
324 * we are and we were the only connection outside.
325 */
326 parent = tsk->real_parent;
327 else
328 /* reparent: our child is in a different pgrp than
329 * we are, and it was the only connection outside.
330 */
331 ignored_task = NULL;
332
333 if (task_pgrp(parent) != pgrp &&
334 task_session(parent) == task_session(tsk) &&
335 will_become_orphaned_pgrp(pgrp, ignored_task) &&
336 has_stopped_jobs(pgrp)) {
337 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
338 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
339 }
340}
341
342#ifdef CONFIG_MEMCG
343/*
344 * A task is exiting. If it owned this mm, find a new owner for the mm.
345 */
346void mm_update_next_owner(struct mm_struct *mm)
347{
348 struct task_struct *c, *g, *p = current;
349
350retry:
351 /*
352 * If the exiting or execing task is not the owner, it's
353 * someone else's problem.
354 */
355 if (mm->owner != p)
356 return;
357 /*
358 * The current owner is exiting/execing and there are no other
359 * candidates. Do not leave the mm pointing to a possibly
360 * freed task structure.
361 */
362 if (atomic_read(&mm->mm_users) <= 1) {
363 WRITE_ONCE(mm->owner, NULL);
364 return;
365 }
366
367 read_lock(&tasklist_lock);
368 /*
369 * Search in the children
370 */
371 list_for_each_entry(c, &p->children, sibling) {
372 if (c->mm == mm)
373 goto assign_new_owner;
374 }
375
376 /*
377 * Search in the siblings
378 */
379 list_for_each_entry(c, &p->real_parent->children, sibling) {
380 if (c->mm == mm)
381 goto assign_new_owner;
382 }
383
384 /*
385 * Search through everything else, we should not get here often.
386 */
387 for_each_process(g) {
388 if (g->flags & PF_KTHREAD)
389 continue;
390 for_each_thread(g, c) {
391 if (c->mm == mm)
392 goto assign_new_owner;
393 if (c->mm)
394 break;
395 }
396 }
397 read_unlock(&tasklist_lock);
398 /*
399 * We found no owner yet mm_users > 1: this implies that we are
400 * most likely racing with swapoff (try_to_unuse()) or /proc or
401 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
402 */
403 WRITE_ONCE(mm->owner, NULL);
404 return;
405
406assign_new_owner:
407 BUG_ON(c == p);
408 get_task_struct(c);
409 /*
410 * The task_lock protects c->mm from changing.
411 * We always want mm->owner->mm == mm
412 */
413 task_lock(c);
414 /*
415 * Delay read_unlock() till we have the task_lock()
416 * to ensure that c does not slip away underneath us
417 */
418 read_unlock(&tasklist_lock);
419 if (c->mm != mm) {
420 task_unlock(c);
421 put_task_struct(c);
422 goto retry;
423 }
424 WRITE_ONCE(mm->owner, c);
425 task_unlock(c);
426 put_task_struct(c);
427}
428#endif /* CONFIG_MEMCG */
429
430/*
431 * Turn us into a lazy TLB process if we
432 * aren't already..
433 */
434static void exit_mm(void)
435{
436 struct mm_struct *mm = current->mm;
437 struct core_state *core_state;
438
439 exit_mm_release(current, mm);
440 if (!mm)
441 return;
442 sync_mm_rss(mm);
443 /*
444 * Serialize with any possible pending coredump.
445 * We must hold mmap_lock around checking core_state
446 * and clearing tsk->mm. The core-inducing thread
447 * will increment ->nr_threads for each thread in the
448 * group with ->mm != NULL.
449 */
450 mmap_read_lock(mm);
451 core_state = mm->core_state;
452 if (core_state) {
453 struct core_thread self;
454
455 mmap_read_unlock(mm);
456
457 self.task = current;
458 if (self.task->flags & PF_SIGNALED)
459 self.next = xchg(&core_state->dumper.next, &self);
460 else
461 self.task = NULL;
462 /*
463 * Implies mb(), the result of xchg() must be visible
464 * to core_state->dumper.
465 */
466 if (atomic_dec_and_test(&core_state->nr_threads))
467 complete(&core_state->startup);
468
469 for (;;) {
470 set_current_state(TASK_UNINTERRUPTIBLE);
471 if (!self.task) /* see coredump_finish() */
472 break;
473 freezable_schedule();
474 }
475 __set_current_state(TASK_RUNNING);
476 mmap_read_lock(mm);
477 }
478 mmgrab(mm);
479 BUG_ON(mm != current->active_mm);
480 /* more a memory barrier than a real lock */
481 task_lock(current);
482 /*
483 * When a thread stops operating on an address space, the loop
484 * in membarrier_private_expedited() may not observe that
485 * tsk->mm, and the loop in membarrier_global_expedited() may
486 * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED
487 * rq->membarrier_state, so those would not issue an IPI.
488 * Membarrier requires a memory barrier after accessing
489 * user-space memory, before clearing tsk->mm or the
490 * rq->membarrier_state.
491 */
492 smp_mb__after_spinlock();
493 local_irq_disable();
494 current->mm = NULL;
495 membarrier_update_current_mm(NULL);
496 enter_lazy_tlb(mm, current);
497 local_irq_enable();
498 task_unlock(current);
499 mmap_read_unlock(mm);
500 mm_update_next_owner(mm);
501 mmput(mm);
502 if (test_thread_flag(TIF_MEMDIE))
503 exit_oom_victim();
504}
505
506static struct task_struct *find_alive_thread(struct task_struct *p)
507{
508 struct task_struct *t;
509
510 for_each_thread(p, t) {
511 if (!(t->flags & PF_EXITING))
512 return t;
513 }
514 return NULL;
515}
516
517static struct task_struct *find_child_reaper(struct task_struct *father,
518 struct list_head *dead)
519 __releases(&tasklist_lock)
520 __acquires(&tasklist_lock)
521{
522 struct pid_namespace *pid_ns = task_active_pid_ns(father);
523 struct task_struct *reaper = pid_ns->child_reaper;
524 struct task_struct *p, *n;
525
526 if (likely(reaper != father))
527 return reaper;
528
529 reaper = find_alive_thread(father);
530 if (reaper) {
531 pid_ns->child_reaper = reaper;
532 return reaper;
533 }
534
535 write_unlock_irq(&tasklist_lock);
536
537 list_for_each_entry_safe(p, n, dead, ptrace_entry) {
538 list_del_init(&p->ptrace_entry);
539 release_task(p);
540 }
541
542 zap_pid_ns_processes(pid_ns);
543 write_lock_irq(&tasklist_lock);
544
545 return father;
546}
547
548/*
549 * When we die, we re-parent all our children, and try to:
550 * 1. give them to another thread in our thread group, if such a member exists
551 * 2. give it to the first ancestor process which prctl'd itself as a
552 * child_subreaper for its children (like a service manager)
553 * 3. give it to the init process (PID 1) in our pid namespace
554 */
555static struct task_struct *find_new_reaper(struct task_struct *father,
556 struct task_struct *child_reaper)
557{
558 struct task_struct *thread, *reaper;
559
560 thread = find_alive_thread(father);
561 if (thread)
562 return thread;
563
564 if (father->signal->has_child_subreaper) {
565 unsigned int ns_level = task_pid(father)->level;
566 /*
567 * Find the first ->is_child_subreaper ancestor in our pid_ns.
568 * We can't check reaper != child_reaper to ensure we do not
569 * cross the namespaces, the exiting parent could be injected
570 * by setns() + fork().
571 * We check pid->level, this is slightly more efficient than
572 * task_active_pid_ns(reaper) != task_active_pid_ns(father).
573 */
574 for (reaper = father->real_parent;
575 task_pid(reaper)->level == ns_level;
576 reaper = reaper->real_parent) {
577 if (reaper == &init_task)
578 break;
579 if (!reaper->signal->is_child_subreaper)
580 continue;
581 thread = find_alive_thread(reaper);
582 if (thread)
583 return thread;
584 }
585 }
586
587 return child_reaper;
588}
589
590/*
591* Any that need to be release_task'd are put on the @dead list.
592 */
593static void reparent_leader(struct task_struct *father, struct task_struct *p,
594 struct list_head *dead)
595{
596 if (unlikely(p->exit_state == EXIT_DEAD))
597 return;
598
599 /* We don't want people slaying init. */
600 p->exit_signal = SIGCHLD;
601
602 /* If it has exited notify the new parent about this child's death. */
603 if (!p->ptrace &&
604 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
605 if (do_notify_parent(p, p->exit_signal)) {
606 p->exit_state = EXIT_DEAD;
607 list_add(&p->ptrace_entry, dead);
608 }
609 }
610
611 kill_orphaned_pgrp(p, father);
612}
613
614/*
615 * This does two things:
616 *
617 * A. Make init inherit all the child processes
618 * B. Check to see if any process groups have become orphaned
619 * as a result of our exiting, and if they have any stopped
620 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
621 */
622static void forget_original_parent(struct task_struct *father,
623 struct list_head *dead)
624{
625 struct task_struct *p, *t, *reaper;
626
627 if (unlikely(!list_empty(&father->ptraced)))
628 exit_ptrace(father, dead);
629
630 /* Can drop and reacquire tasklist_lock */
631 reaper = find_child_reaper(father, dead);
632 if (list_empty(&father->children))
633 return;
634
635 reaper = find_new_reaper(father, reaper);
636 list_for_each_entry(p, &father->children, sibling) {
637 for_each_thread(p, t) {
638 RCU_INIT_POINTER(t->real_parent, reaper);
639 BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father));
640 if (likely(!t->ptrace))
641 t->parent = t->real_parent;
642 if (t->pdeath_signal)
643 group_send_sig_info(t->pdeath_signal,
644 SEND_SIG_NOINFO, t,
645 PIDTYPE_TGID);
646 }
647 /*
648 * If this is a threaded reparent there is no need to
649 * notify anyone anything has happened.
650 */
651 if (!same_thread_group(reaper, father))
652 reparent_leader(father, p, dead);
653 }
654 list_splice_tail_init(&father->children, &reaper->children);
655}
656
657/*
658 * Send signals to all our closest relatives so that they know
659 * to properly mourn us..
660 */
661static void exit_notify(struct task_struct *tsk, int group_dead)
662{
663 bool autoreap;
664 struct task_struct *p, *n;
665 LIST_HEAD(dead);
666
667 write_lock_irq(&tasklist_lock);
668 forget_original_parent(tsk, &dead);
669
670 if (group_dead)
671 kill_orphaned_pgrp(tsk->group_leader, NULL);
672
673 tsk->exit_state = EXIT_ZOMBIE;
674 if (unlikely(tsk->ptrace)) {
675 int sig = thread_group_leader(tsk) &&
676 thread_group_empty(tsk) &&
677 !ptrace_reparented(tsk) ?
678 tsk->exit_signal : SIGCHLD;
679 autoreap = do_notify_parent(tsk, sig);
680 } else if (thread_group_leader(tsk)) {
681 autoreap = thread_group_empty(tsk) &&
682 do_notify_parent(tsk, tsk->exit_signal);
683 } else {
684 autoreap = true;
685 }
686
687 if (autoreap) {
688 tsk->exit_state = EXIT_DEAD;
689 list_add(&tsk->ptrace_entry, &dead);
690 }
691
692 /* mt-exec, de_thread() is waiting for group leader */
693 if (unlikely(tsk->signal->notify_count < 0))
694 wake_up_process(tsk->signal->group_exit_task);
695 write_unlock_irq(&tasklist_lock);
696
697 list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
698 list_del_init(&p->ptrace_entry);
699 release_task(p);
700 }
701}
702
703#ifdef CONFIG_DEBUG_STACK_USAGE
704static void check_stack_usage(void)
705{
706 static DEFINE_SPINLOCK(low_water_lock);
707 static int lowest_to_date = THREAD_SIZE;
708 unsigned long free;
709
710 free = stack_not_used(current);
711
712 if (free >= lowest_to_date)
713 return;
714
715 spin_lock(&low_water_lock);
716 if (free < lowest_to_date) {
717 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
718 current->comm, task_pid_nr(current), free);
719 lowest_to_date = free;
720 }
721 spin_unlock(&low_water_lock);
722}
723#else
724static inline void check_stack_usage(void) {}
725#endif
726
727void __noreturn do_exit(long code)
728{
729 struct task_struct *tsk = current;
730 int group_dead;
731
732 /*
733 * We can get here from a kernel oops, sometimes with preemption off.
734 * Start by checking for critical errors.
735 * Then fix up important state like USER_DS and preemption.
736 * Then do everything else.
737 */
738
739 WARN_ON(blk_needs_flush_plug(tsk));
740
741 if (unlikely(in_interrupt()))
742 panic("Aiee, killing interrupt handler!");
743 if (unlikely(!tsk->pid))
744 panic("Attempted to kill the idle task!");
745
746 /*
747 * If do_exit is called because this processes oopsed, it's possible
748 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
749 * continuing. Amongst other possible reasons, this is to prevent
750 * mm_release()->clear_child_tid() from writing to a user-controlled
751 * kernel address.
752 */
753 force_uaccess_begin();
754
755 if (unlikely(in_atomic())) {
756 pr_info("note: %s[%d] exited with preempt_count %d\n",
757 current->comm, task_pid_nr(current),
758 preempt_count());
759 preempt_count_set(PREEMPT_ENABLED);
760 }
761
762 profile_task_exit(tsk);
763 kcov_task_exit(tsk);
764
765 ptrace_event(PTRACE_EVENT_EXIT, code);
766
767 validate_creds_for_do_exit(tsk);
768
769 /*
770 * We're taking recursive faults here in do_exit. Safest is to just
771 * leave this task alone and wait for reboot.
772 */
773 if (unlikely(tsk->flags & PF_EXITING)) {
774 pr_alert("Fixing recursive fault but reboot is needed!\n");
775 futex_exit_recursive(tsk);
776 set_current_state(TASK_UNINTERRUPTIBLE);
777 schedule();
778 }
779
780 io_uring_files_cancel(tsk->files);
781 exit_signals(tsk); /* sets PF_EXITING */
782
783 /* sync mm's RSS info before statistics gathering */
784 if (tsk->mm)
785 sync_mm_rss(tsk->mm);
786 acct_update_integrals(tsk);
787 group_dead = atomic_dec_and_test(&tsk->signal->live);
788 if (group_dead) {
789 /*
790 * If the last thread of global init has exited, panic
791 * immediately to get a useable coredump.
792 */
793 if (unlikely(is_global_init(tsk)))
794 panic("Attempted to kill init! exitcode=0x%08x\n",
795 tsk->signal->group_exit_code ?: (int)code);
796
797#ifdef CONFIG_POSIX_TIMERS
798 hrtimer_cancel(&tsk->signal->real_timer);
799 exit_itimers(tsk->signal);
800#endif
801 if (tsk->mm)
802 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
803 }
804 acct_collect(code, group_dead);
805 if (group_dead)
806 tty_audit_exit();
807 audit_free(tsk);
808
809 tsk->exit_code = code;
810 taskstats_exit(tsk, group_dead);
811
812 exit_mm();
813
814 if (group_dead)
815 acct_process();
816 trace_sched_process_exit(tsk);
817
818 exit_sem(tsk);
819 exit_shm(tsk);
820 exit_files(tsk);
821 exit_fs(tsk);
822 if (group_dead)
823 disassociate_ctty(1);
824 exit_task_namespaces(tsk);
825 exit_task_work(tsk);
826 exit_thread(tsk);
827
828 /*
829 * Flush inherited counters to the parent - before the parent
830 * gets woken up by child-exit notifications.
831 *
832 * because of cgroup mode, must be called before cgroup_exit()
833 */
834 perf_event_exit_task(tsk);
835
836 sched_autogroup_exit_task(tsk);
837 cgroup_exit(tsk);
838
839 /*
840 * FIXME: do that only when needed, using sched_exit tracepoint
841 */
842 flush_ptrace_hw_breakpoint(tsk);
843
844 exit_tasks_rcu_start();
845 exit_notify(tsk, group_dead);
846 proc_exit_connector(tsk);
847 mpol_put_task_policy(tsk);
848#ifdef CONFIG_FUTEX
849 if (unlikely(current->pi_state_cache))
850 kfree(current->pi_state_cache);
851#endif
852 /*
853 * Make sure we are holding no locks:
854 */
855 debug_check_no_locks_held();
856
857 if (tsk->io_context)
858 exit_io_context(tsk);
859
860 if (tsk->splice_pipe)
861 free_pipe_info(tsk->splice_pipe);
862
863 if (tsk->task_frag.page)
864 put_page(tsk->task_frag.page);
865
866 validate_creds_for_do_exit(tsk);
867
868 check_stack_usage();
869 preempt_disable();
870 if (tsk->nr_dirtied)
871 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
872 exit_rcu();
873 exit_tasks_rcu_finish();
874
875 lockdep_free_task(tsk);
876 do_task_dead();
877}
878EXPORT_SYMBOL_GPL(do_exit);
879
880void complete_and_exit(struct completion *comp, long code)
881{
882 if (comp)
883 complete(comp);
884
885 do_exit(code);
886}
887EXPORT_SYMBOL(complete_and_exit);
888
889SYSCALL_DEFINE1(exit, int, error_code)
890{
891 do_exit((error_code&0xff)<<8);
892}
893
894/*
895 * Take down every thread in the group. This is called by fatal signals
896 * as well as by sys_exit_group (below).
897 */
898void
899do_group_exit(int exit_code)
900{
901 struct signal_struct *sig = current->signal;
902
903 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
904
905 if (signal_group_exit(sig))
906 exit_code = sig->group_exit_code;
907 else if (!thread_group_empty(current)) {
908 struct sighand_struct *const sighand = current->sighand;
909
910 spin_lock_irq(&sighand->siglock);
911 if (signal_group_exit(sig))
912 /* Another thread got here before we took the lock. */
913 exit_code = sig->group_exit_code;
914 else {
915 sig->group_exit_code = exit_code;
916 sig->flags = SIGNAL_GROUP_EXIT;
917 zap_other_threads(current);
918 }
919 spin_unlock_irq(&sighand->siglock);
920 }
921
922 do_exit(exit_code);
923 /* NOTREACHED */
924}
925
926/*
927 * this kills every thread in the thread group. Note that any externally
928 * wait4()-ing process will get the correct exit code - even if this
929 * thread is not the thread group leader.
930 */
931SYSCALL_DEFINE1(exit_group, int, error_code)
932{
933 do_group_exit((error_code & 0xff) << 8);
934 /* NOTREACHED */
935 return 0;
936}
937
938struct waitid_info {
939 pid_t pid;
940 uid_t uid;
941 int status;
942 int cause;
943};
944
945struct wait_opts {
946 enum pid_type wo_type;
947 int wo_flags;
948 struct pid *wo_pid;
949
950 struct waitid_info *wo_info;
951 int wo_stat;
952 struct rusage *wo_rusage;
953
954 wait_queue_entry_t child_wait;
955 int notask_error;
956};
957
958static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
959{
960 return wo->wo_type == PIDTYPE_MAX ||
961 task_pid_type(p, wo->wo_type) == wo->wo_pid;
962}
963
964static int
965eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
966{
967 if (!eligible_pid(wo, p))
968 return 0;
969
970 /*
971 * Wait for all children (clone and not) if __WALL is set or
972 * if it is traced by us.
973 */
974 if (ptrace || (wo->wo_flags & __WALL))
975 return 1;
976
977 /*
978 * Otherwise, wait for clone children *only* if __WCLONE is set;
979 * otherwise, wait for non-clone children *only*.
980 *
981 * Note: a "clone" child here is one that reports to its parent
982 * using a signal other than SIGCHLD, or a non-leader thread which
983 * we can only see if it is traced by us.
984 */
985 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
986 return 0;
987
988 return 1;
989}
990
991/*
992 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
993 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
994 * the lock and this task is uninteresting. If we return nonzero, we have
995 * released the lock and the system call should return.
996 */
997static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
998{
999 int state, status;
1000 pid_t pid = task_pid_vnr(p);
1001 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1002 struct waitid_info *infop;
1003
1004 if (!likely(wo->wo_flags & WEXITED))
1005 return 0;
1006
1007 if (unlikely(wo->wo_flags & WNOWAIT)) {
1008 status = p->exit_code;
1009 get_task_struct(p);
1010 read_unlock(&tasklist_lock);
1011 sched_annotate_sleep();
1012 if (wo->wo_rusage)
1013 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1014 put_task_struct(p);
1015 goto out_info;
1016 }
1017 /*
1018 * Move the task's state to DEAD/TRACE, only one thread can do this.
1019 */
1020 state = (ptrace_reparented(p) && thread_group_leader(p)) ?
1021 EXIT_TRACE : EXIT_DEAD;
1022 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1023 return 0;
1024 /*
1025 * We own this thread, nobody else can reap it.
1026 */
1027 read_unlock(&tasklist_lock);
1028 sched_annotate_sleep();
1029
1030 /*
1031 * Check thread_group_leader() to exclude the traced sub-threads.
1032 */
1033 if (state == EXIT_DEAD && thread_group_leader(p)) {
1034 struct signal_struct *sig = p->signal;
1035 struct signal_struct *psig = current->signal;
1036 unsigned long maxrss;
1037 u64 tgutime, tgstime;
1038
1039 /*
1040 * The resource counters for the group leader are in its
1041 * own task_struct. Those for dead threads in the group
1042 * are in its signal_struct, as are those for the child
1043 * processes it has previously reaped. All these
1044 * accumulate in the parent's signal_struct c* fields.
1045 *
1046 * We don't bother to take a lock here to protect these
1047 * p->signal fields because the whole thread group is dead
1048 * and nobody can change them.
1049 *
1050 * psig->stats_lock also protects us from our sub-theads
1051 * which can reap other children at the same time. Until
1052 * we change k_getrusage()-like users to rely on this lock
1053 * we have to take ->siglock as well.
1054 *
1055 * We use thread_group_cputime_adjusted() to get times for
1056 * the thread group, which consolidates times for all threads
1057 * in the group including the group leader.
1058 */
1059 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1060 spin_lock_irq(¤t->sighand->siglock);
1061 write_seqlock(&psig->stats_lock);
1062 psig->cutime += tgutime + sig->cutime;
1063 psig->cstime += tgstime + sig->cstime;
1064 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1065 psig->cmin_flt +=
1066 p->min_flt + sig->min_flt + sig->cmin_flt;
1067 psig->cmaj_flt +=
1068 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1069 psig->cnvcsw +=
1070 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1071 psig->cnivcsw +=
1072 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1073 psig->cinblock +=
1074 task_io_get_inblock(p) +
1075 sig->inblock + sig->cinblock;
1076 psig->coublock +=
1077 task_io_get_oublock(p) +
1078 sig->oublock + sig->coublock;
1079 maxrss = max(sig->maxrss, sig->cmaxrss);
1080 if (psig->cmaxrss < maxrss)
1081 psig->cmaxrss = maxrss;
1082 task_io_accounting_add(&psig->ioac, &p->ioac);
1083 task_io_accounting_add(&psig->ioac, &sig->ioac);
1084 write_sequnlock(&psig->stats_lock);
1085 spin_unlock_irq(¤t->sighand->siglock);
1086 }
1087
1088 if (wo->wo_rusage)
1089 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1090 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1091 ? p->signal->group_exit_code : p->exit_code;
1092 wo->wo_stat = status;
1093
1094 if (state == EXIT_TRACE) {
1095 write_lock_irq(&tasklist_lock);
1096 /* We dropped tasklist, ptracer could die and untrace */
1097 ptrace_unlink(p);
1098
1099 /* If parent wants a zombie, don't release it now */
1100 state = EXIT_ZOMBIE;
1101 if (do_notify_parent(p, p->exit_signal))
1102 state = EXIT_DEAD;
1103 p->exit_state = state;
1104 write_unlock_irq(&tasklist_lock);
1105 }
1106 if (state == EXIT_DEAD)
1107 release_task(p);
1108
1109out_info:
1110 infop = wo->wo_info;
1111 if (infop) {
1112 if ((status & 0x7f) == 0) {
1113 infop->cause = CLD_EXITED;
1114 infop->status = status >> 8;
1115 } else {
1116 infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1117 infop->status = status & 0x7f;
1118 }
1119 infop->pid = pid;
1120 infop->uid = uid;
1121 }
1122
1123 return pid;
1124}
1125
1126static int *task_stopped_code(struct task_struct *p, bool ptrace)
1127{
1128 if (ptrace) {
1129 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING))
1130 return &p->exit_code;
1131 } else {
1132 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1133 return &p->signal->group_exit_code;
1134 }
1135 return NULL;
1136}
1137
1138/**
1139 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1140 * @wo: wait options
1141 * @ptrace: is the wait for ptrace
1142 * @p: task to wait for
1143 *
1144 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1145 *
1146 * CONTEXT:
1147 * read_lock(&tasklist_lock), which is released if return value is
1148 * non-zero. Also, grabs and releases @p->sighand->siglock.
1149 *
1150 * RETURNS:
1151 * 0 if wait condition didn't exist and search for other wait conditions
1152 * should continue. Non-zero return, -errno on failure and @p's pid on
1153 * success, implies that tasklist_lock is released and wait condition
1154 * search should terminate.
1155 */
1156static int wait_task_stopped(struct wait_opts *wo,
1157 int ptrace, struct task_struct *p)
1158{
1159 struct waitid_info *infop;
1160 int exit_code, *p_code, why;
1161 uid_t uid = 0; /* unneeded, required by compiler */
1162 pid_t pid;
1163
1164 /*
1165 * Traditionally we see ptrace'd stopped tasks regardless of options.
1166 */
1167 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1168 return 0;
1169
1170 if (!task_stopped_code(p, ptrace))
1171 return 0;
1172
1173 exit_code = 0;
1174 spin_lock_irq(&p->sighand->siglock);
1175
1176 p_code = task_stopped_code(p, ptrace);
1177 if (unlikely(!p_code))
1178 goto unlock_sig;
1179
1180 exit_code = *p_code;
1181 if (!exit_code)
1182 goto unlock_sig;
1183
1184 if (!unlikely(wo->wo_flags & WNOWAIT))
1185 *p_code = 0;
1186
1187 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1188unlock_sig:
1189 spin_unlock_irq(&p->sighand->siglock);
1190 if (!exit_code)
1191 return 0;
1192
1193 /*
1194 * Now we are pretty sure this task is interesting.
1195 * Make sure it doesn't get reaped out from under us while we
1196 * give up the lock and then examine it below. We don't want to
1197 * keep holding onto the tasklist_lock while we call getrusage and
1198 * possibly take page faults for user memory.
1199 */
1200 get_task_struct(p);
1201 pid = task_pid_vnr(p);
1202 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1203 read_unlock(&tasklist_lock);
1204 sched_annotate_sleep();
1205 if (wo->wo_rusage)
1206 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1207 put_task_struct(p);
1208
1209 if (likely(!(wo->wo_flags & WNOWAIT)))
1210 wo->wo_stat = (exit_code << 8) | 0x7f;
1211
1212 infop = wo->wo_info;
1213 if (infop) {
1214 infop->cause = why;
1215 infop->status = exit_code;
1216 infop->pid = pid;
1217 infop->uid = uid;
1218 }
1219 return pid;
1220}
1221
1222/*
1223 * Handle do_wait work for one task in a live, non-stopped state.
1224 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1225 * the lock and this task is uninteresting. If we return nonzero, we have
1226 * released the lock and the system call should return.
1227 */
1228static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1229{
1230 struct waitid_info *infop;
1231 pid_t pid;
1232 uid_t uid;
1233
1234 if (!unlikely(wo->wo_flags & WCONTINUED))
1235 return 0;
1236
1237 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1238 return 0;
1239
1240 spin_lock_irq(&p->sighand->siglock);
1241 /* Re-check with the lock held. */
1242 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1243 spin_unlock_irq(&p->sighand->siglock);
1244 return 0;
1245 }
1246 if (!unlikely(wo->wo_flags & WNOWAIT))
1247 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1248 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1249 spin_unlock_irq(&p->sighand->siglock);
1250
1251 pid = task_pid_vnr(p);
1252 get_task_struct(p);
1253 read_unlock(&tasklist_lock);
1254 sched_annotate_sleep();
1255 if (wo->wo_rusage)
1256 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1257 put_task_struct(p);
1258
1259 infop = wo->wo_info;
1260 if (!infop) {
1261 wo->wo_stat = 0xffff;
1262 } else {
1263 infop->cause = CLD_CONTINUED;
1264 infop->pid = pid;
1265 infop->uid = uid;
1266 infop->status = SIGCONT;
1267 }
1268 return pid;
1269}
1270
1271/*
1272 * Consider @p for a wait by @parent.
1273 *
1274 * -ECHILD should be in ->notask_error before the first call.
1275 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1276 * Returns zero if the search for a child should continue;
1277 * then ->notask_error is 0 if @p is an eligible child,
1278 * or still -ECHILD.
1279 */
1280static int wait_consider_task(struct wait_opts *wo, int ptrace,
1281 struct task_struct *p)
1282{
1283 /*
1284 * We can race with wait_task_zombie() from another thread.
1285 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1286 * can't confuse the checks below.
1287 */
1288 int exit_state = READ_ONCE(p->exit_state);
1289 int ret;
1290
1291 if (unlikely(exit_state == EXIT_DEAD))
1292 return 0;
1293
1294 ret = eligible_child(wo, ptrace, p);
1295 if (!ret)
1296 return ret;
1297
1298 if (unlikely(exit_state == EXIT_TRACE)) {
1299 /*
1300 * ptrace == 0 means we are the natural parent. In this case
1301 * we should clear notask_error, debugger will notify us.
1302 */
1303 if (likely(!ptrace))
1304 wo->notask_error = 0;
1305 return 0;
1306 }
1307
1308 if (likely(!ptrace) && unlikely(p->ptrace)) {
1309 /*
1310 * If it is traced by its real parent's group, just pretend
1311 * the caller is ptrace_do_wait() and reap this child if it
1312 * is zombie.
1313 *
1314 * This also hides group stop state from real parent; otherwise
1315 * a single stop can be reported twice as group and ptrace stop.
1316 * If a ptracer wants to distinguish these two events for its
1317 * own children it should create a separate process which takes
1318 * the role of real parent.
1319 */
1320 if (!ptrace_reparented(p))
1321 ptrace = 1;
1322 }
1323
1324 /* slay zombie? */
1325 if (exit_state == EXIT_ZOMBIE) {
1326 /* we don't reap group leaders with subthreads */
1327 if (!delay_group_leader(p)) {
1328 /*
1329 * A zombie ptracee is only visible to its ptracer.
1330 * Notification and reaping will be cascaded to the
1331 * real parent when the ptracer detaches.
1332 */
1333 if (unlikely(ptrace) || likely(!p->ptrace))
1334 return wait_task_zombie(wo, p);
1335 }
1336
1337 /*
1338 * Allow access to stopped/continued state via zombie by
1339 * falling through. Clearing of notask_error is complex.
1340 *
1341 * When !@ptrace:
1342 *
1343 * If WEXITED is set, notask_error should naturally be
1344 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1345 * so, if there are live subthreads, there are events to
1346 * wait for. If all subthreads are dead, it's still safe
1347 * to clear - this function will be called again in finite
1348 * amount time once all the subthreads are released and
1349 * will then return without clearing.
1350 *
1351 * When @ptrace:
1352 *
1353 * Stopped state is per-task and thus can't change once the
1354 * target task dies. Only continued and exited can happen.
1355 * Clear notask_error if WCONTINUED | WEXITED.
1356 */
1357 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1358 wo->notask_error = 0;
1359 } else {
1360 /*
1361 * @p is alive and it's gonna stop, continue or exit, so
1362 * there always is something to wait for.
1363 */
1364 wo->notask_error = 0;
1365 }
1366
1367 /*
1368 * Wait for stopped. Depending on @ptrace, different stopped state
1369 * is used and the two don't interact with each other.
1370 */
1371 ret = wait_task_stopped(wo, ptrace, p);
1372 if (ret)
1373 return ret;
1374
1375 /*
1376 * Wait for continued. There's only one continued state and the
1377 * ptracer can consume it which can confuse the real parent. Don't
1378 * use WCONTINUED from ptracer. You don't need or want it.
1379 */
1380 return wait_task_continued(wo, p);
1381}
1382
1383/*
1384 * Do the work of do_wait() for one thread in the group, @tsk.
1385 *
1386 * -ECHILD should be in ->notask_error before the first call.
1387 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1388 * Returns zero if the search for a child should continue; then
1389 * ->notask_error is 0 if there were any eligible children,
1390 * or still -ECHILD.
1391 */
1392static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1393{
1394 struct task_struct *p;
1395
1396 list_for_each_entry(p, &tsk->children, sibling) {
1397 int ret = wait_consider_task(wo, 0, p);
1398
1399 if (ret)
1400 return ret;
1401 }
1402
1403 return 0;
1404}
1405
1406static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1407{
1408 struct task_struct *p;
1409
1410 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1411 int ret = wait_consider_task(wo, 1, p);
1412
1413 if (ret)
1414 return ret;
1415 }
1416
1417 return 0;
1418}
1419
1420static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode,
1421 int sync, void *key)
1422{
1423 struct wait_opts *wo = container_of(wait, struct wait_opts,
1424 child_wait);
1425 struct task_struct *p = key;
1426
1427 if (!eligible_pid(wo, p))
1428 return 0;
1429
1430 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1431 return 0;
1432
1433 return default_wake_function(wait, mode, sync, key);
1434}
1435
1436void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1437{
1438 __wake_up_sync_key(&parent->signal->wait_chldexit,
1439 TASK_INTERRUPTIBLE, p);
1440}
1441
1442static bool is_effectively_child(struct wait_opts *wo, bool ptrace,
1443 struct task_struct *target)
1444{
1445 struct task_struct *parent =
1446 !ptrace ? target->real_parent : target->parent;
1447
1448 return current == parent || (!(wo->wo_flags & __WNOTHREAD) &&
1449 same_thread_group(current, parent));
1450}
1451
1452/*
1453 * Optimization for waiting on PIDTYPE_PID. No need to iterate through child
1454 * and tracee lists to find the target task.
1455 */
1456static int do_wait_pid(struct wait_opts *wo)
1457{
1458 bool ptrace;
1459 struct task_struct *target;
1460 int retval;
1461
1462 ptrace = false;
1463 target = pid_task(wo->wo_pid, PIDTYPE_TGID);
1464 if (target && is_effectively_child(wo, ptrace, target)) {
1465 retval = wait_consider_task(wo, ptrace, target);
1466 if (retval)
1467 return retval;
1468 }
1469
1470 ptrace = true;
1471 target = pid_task(wo->wo_pid, PIDTYPE_PID);
1472 if (target && target->ptrace &&
1473 is_effectively_child(wo, ptrace, target)) {
1474 retval = wait_consider_task(wo, ptrace, target);
1475 if (retval)
1476 return retval;
1477 }
1478
1479 return 0;
1480}
1481
1482static long do_wait(struct wait_opts *wo)
1483{
1484 int retval;
1485
1486 trace_sched_process_wait(wo->wo_pid);
1487
1488 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1489 wo->child_wait.private = current;
1490 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1491repeat:
1492 /*
1493 * If there is nothing that can match our criteria, just get out.
1494 * We will clear ->notask_error to zero if we see any child that
1495 * might later match our criteria, even if we are not able to reap
1496 * it yet.
1497 */
1498 wo->notask_error = -ECHILD;
1499 if ((wo->wo_type < PIDTYPE_MAX) &&
1500 (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type)))
1501 goto notask;
1502
1503 set_current_state(TASK_INTERRUPTIBLE);
1504 read_lock(&tasklist_lock);
1505
1506 if (wo->wo_type == PIDTYPE_PID) {
1507 retval = do_wait_pid(wo);
1508 if (retval)
1509 goto end;
1510 } else {
1511 struct task_struct *tsk = current;
1512
1513 do {
1514 retval = do_wait_thread(wo, tsk);
1515 if (retval)
1516 goto end;
1517
1518 retval = ptrace_do_wait(wo, tsk);
1519 if (retval)
1520 goto end;
1521
1522 if (wo->wo_flags & __WNOTHREAD)
1523 break;
1524 } while_each_thread(current, tsk);
1525 }
1526 read_unlock(&tasklist_lock);
1527
1528notask:
1529 retval = wo->notask_error;
1530 if (!retval && !(wo->wo_flags & WNOHANG)) {
1531 retval = -ERESTARTSYS;
1532 if (!signal_pending(current)) {
1533 schedule();
1534 goto repeat;
1535 }
1536 }
1537end:
1538 __set_current_state(TASK_RUNNING);
1539 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1540 return retval;
1541}
1542
1543static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
1544 int options, struct rusage *ru)
1545{
1546 struct wait_opts wo;
1547 struct pid *pid = NULL;
1548 enum pid_type type;
1549 long ret;
1550 unsigned int f_flags = 0;
1551
1552 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
1553 __WNOTHREAD|__WCLONE|__WALL))
1554 return -EINVAL;
1555 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1556 return -EINVAL;
1557
1558 switch (which) {
1559 case P_ALL:
1560 type = PIDTYPE_MAX;
1561 break;
1562 case P_PID:
1563 type = PIDTYPE_PID;
1564 if (upid <= 0)
1565 return -EINVAL;
1566
1567 pid = find_get_pid(upid);
1568 break;
1569 case P_PGID:
1570 type = PIDTYPE_PGID;
1571 if (upid < 0)
1572 return -EINVAL;
1573
1574 if (upid)
1575 pid = find_get_pid(upid);
1576 else
1577 pid = get_task_pid(current, PIDTYPE_PGID);
1578 break;
1579 case P_PIDFD:
1580 type = PIDTYPE_PID;
1581 if (upid < 0)
1582 return -EINVAL;
1583
1584 pid = pidfd_get_pid(upid, &f_flags);
1585 if (IS_ERR(pid))
1586 return PTR_ERR(pid);
1587
1588 break;
1589 default:
1590 return -EINVAL;
1591 }
1592
1593 wo.wo_type = type;
1594 wo.wo_pid = pid;
1595 wo.wo_flags = options;
1596 wo.wo_info = infop;
1597 wo.wo_rusage = ru;
1598 if (f_flags & O_NONBLOCK)
1599 wo.wo_flags |= WNOHANG;
1600
1601 ret = do_wait(&wo);
1602 if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK))
1603 ret = -EAGAIN;
1604
1605 put_pid(pid);
1606 return ret;
1607}
1608
1609SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1610 infop, int, options, struct rusage __user *, ru)
1611{
1612 struct rusage r;
1613 struct waitid_info info = {.status = 0};
1614 long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
1615 int signo = 0;
1616
1617 if (err > 0) {
1618 signo = SIGCHLD;
1619 err = 0;
1620 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1621 return -EFAULT;
1622 }
1623 if (!infop)
1624 return err;
1625
1626 if (!user_write_access_begin(infop, sizeof(*infop)))
1627 return -EFAULT;
1628
1629 unsafe_put_user(signo, &infop->si_signo, Efault);
1630 unsafe_put_user(0, &infop->si_errno, Efault);
1631 unsafe_put_user(info.cause, &infop->si_code, Efault);
1632 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1633 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1634 unsafe_put_user(info.status, &infop->si_status, Efault);
1635 user_write_access_end();
1636 return err;
1637Efault:
1638 user_write_access_end();
1639 return -EFAULT;
1640}
1641
1642long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
1643 struct rusage *ru)
1644{
1645 struct wait_opts wo;
1646 struct pid *pid = NULL;
1647 enum pid_type type;
1648 long ret;
1649
1650 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1651 __WNOTHREAD|__WCLONE|__WALL))
1652 return -EINVAL;
1653
1654 /* -INT_MIN is not defined */
1655 if (upid == INT_MIN)
1656 return -ESRCH;
1657
1658 if (upid == -1)
1659 type = PIDTYPE_MAX;
1660 else if (upid < 0) {
1661 type = PIDTYPE_PGID;
1662 pid = find_get_pid(-upid);
1663 } else if (upid == 0) {
1664 type = PIDTYPE_PGID;
1665 pid = get_task_pid(current, PIDTYPE_PGID);
1666 } else /* upid > 0 */ {
1667 type = PIDTYPE_PID;
1668 pid = find_get_pid(upid);
1669 }
1670
1671 wo.wo_type = type;
1672 wo.wo_pid = pid;
1673 wo.wo_flags = options | WEXITED;
1674 wo.wo_info = NULL;
1675 wo.wo_stat = 0;
1676 wo.wo_rusage = ru;
1677 ret = do_wait(&wo);
1678 put_pid(pid);
1679 if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
1680 ret = -EFAULT;
1681
1682 return ret;
1683}
1684
1685int kernel_wait(pid_t pid, int *stat)
1686{
1687 struct wait_opts wo = {
1688 .wo_type = PIDTYPE_PID,
1689 .wo_pid = find_get_pid(pid),
1690 .wo_flags = WEXITED,
1691 };
1692 int ret;
1693
1694 ret = do_wait(&wo);
1695 if (ret > 0 && wo.wo_stat)
1696 *stat = wo.wo_stat;
1697 put_pid(wo.wo_pid);
1698 return ret;
1699}
1700
1701SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1702 int, options, struct rusage __user *, ru)
1703{
1704 struct rusage r;
1705 long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL);
1706
1707 if (err > 0) {
1708 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1709 return -EFAULT;
1710 }
1711 return err;
1712}
1713
1714#ifdef __ARCH_WANT_SYS_WAITPID
1715
1716/*
1717 * sys_waitpid() remains for compatibility. waitpid() should be
1718 * implemented by calling sys_wait4() from libc.a.
1719 */
1720SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1721{
1722 return kernel_wait4(pid, stat_addr, options, NULL);
1723}
1724
1725#endif
1726
1727#ifdef CONFIG_COMPAT
1728COMPAT_SYSCALL_DEFINE4(wait4,
1729 compat_pid_t, pid,
1730 compat_uint_t __user *, stat_addr,
1731 int, options,
1732 struct compat_rusage __user *, ru)
1733{
1734 struct rusage r;
1735 long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL);
1736 if (err > 0) {
1737 if (ru && put_compat_rusage(&r, ru))
1738 return -EFAULT;
1739 }
1740 return err;
1741}
1742
1743COMPAT_SYSCALL_DEFINE5(waitid,
1744 int, which, compat_pid_t, pid,
1745 struct compat_siginfo __user *, infop, int, options,
1746 struct compat_rusage __user *, uru)
1747{
1748 struct rusage ru;
1749 struct waitid_info info = {.status = 0};
1750 long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);
1751 int signo = 0;
1752 if (err > 0) {
1753 signo = SIGCHLD;
1754 err = 0;
1755 if (uru) {
1756 /* kernel_waitid() overwrites everything in ru */
1757 if (COMPAT_USE_64BIT_TIME)
1758 err = copy_to_user(uru, &ru, sizeof(ru));
1759 else
1760 err = put_compat_rusage(&ru, uru);
1761 if (err)
1762 return -EFAULT;
1763 }
1764 }
1765
1766 if (!infop)
1767 return err;
1768
1769 if (!user_write_access_begin(infop, sizeof(*infop)))
1770 return -EFAULT;
1771
1772 unsafe_put_user(signo, &infop->si_signo, Efault);
1773 unsafe_put_user(0, &infop->si_errno, Efault);
1774 unsafe_put_user(info.cause, &infop->si_code, Efault);
1775 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1776 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1777 unsafe_put_user(info.status, &infop->si_status, Efault);
1778 user_write_access_end();
1779 return err;
1780Efault:
1781 user_write_access_end();
1782 return -EFAULT;
1783}
1784#endif
1785
1786/**
1787 * thread_group_exited - check that a thread group has exited
1788 * @pid: tgid of thread group to be checked.
1789 *
1790 * Test if the thread group represented by tgid has exited (all
1791 * threads are zombies, dead or completely gone).
1792 *
1793 * Return: true if the thread group has exited. false otherwise.
1794 */
1795bool thread_group_exited(struct pid *pid)
1796{
1797 struct task_struct *task;
1798 bool exited;
1799
1800 rcu_read_lock();
1801 task = pid_task(pid, PIDTYPE_PID);
1802 exited = !task ||
1803 (READ_ONCE(task->exit_state) && thread_group_empty(task));
1804 rcu_read_unlock();
1805
1806 return exited;
1807}
1808EXPORT_SYMBOL(thread_group_exited);
1809
1810__weak void abort(void)
1811{
1812 BUG();
1813
1814 /* if that doesn't kill us, halt */
1815 panic("Oops failed to kill thread");
1816}
1817EXPORT_SYMBOL(abort);