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