Loading...
1/*
2 * linux/kernel/exit.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7#include <linux/mm.h>
8#include <linux/slab.h>
9#include <linux/sched/autogroup.h>
10#include <linux/sched/mm.h>
11#include <linux/sched/stat.h>
12#include <linux/sched/task.h>
13#include <linux/sched/task_stack.h>
14#include <linux/sched/cputime.h>
15#include <linux/interrupt.h>
16#include <linux/module.h>
17#include <linux/capability.h>
18#include <linux/completion.h>
19#include <linux/personality.h>
20#include <linux/tty.h>
21#include <linux/iocontext.h>
22#include <linux/key.h>
23#include <linux/cpu.h>
24#include <linux/acct.h>
25#include <linux/tsacct_kern.h>
26#include <linux/file.h>
27#include <linux/fdtable.h>
28#include <linux/freezer.h>
29#include <linux/binfmts.h>
30#include <linux/nsproxy.h>
31#include <linux/pid_namespace.h>
32#include <linux/ptrace.h>
33#include <linux/profile.h>
34#include <linux/mount.h>
35#include <linux/proc_fs.h>
36#include <linux/kthread.h>
37#include <linux/mempolicy.h>
38#include <linux/taskstats_kern.h>
39#include <linux/delayacct.h>
40#include <linux/cgroup.h>
41#include <linux/syscalls.h>
42#include <linux/signal.h>
43#include <linux/posix-timers.h>
44#include <linux/cn_proc.h>
45#include <linux/mutex.h>
46#include <linux/futex.h>
47#include <linux/pipe_fs_i.h>
48#include <linux/audit.h> /* for audit_free() */
49#include <linux/resource.h>
50#include <linux/blkdev.h>
51#include <linux/task_io_accounting_ops.h>
52#include <linux/tracehook.h>
53#include <linux/fs_struct.h>
54#include <linux/init_task.h>
55#include <linux/perf_event.h>
56#include <trace/events/sched.h>
57#include <linux/hw_breakpoint.h>
58#include <linux/oom.h>
59#include <linux/writeback.h>
60#include <linux/shm.h>
61#include <linux/kcov.h>
62#include <linux/random.h>
63#include <linux/rcuwait.h>
64#include <linux/compat.h>
65
66#include <linux/uaccess.h>
67#include <asm/unistd.h>
68#include <asm/pgtable.h>
69#include <asm/mmu_context.h>
70
71static void __unhash_process(struct task_struct *p, bool group_dead)
72{
73 nr_threads--;
74 detach_pid(p, PIDTYPE_PID);
75 if (group_dead) {
76 detach_pid(p, PIDTYPE_PGID);
77 detach_pid(p, PIDTYPE_SID);
78
79 list_del_rcu(&p->tasks);
80 list_del_init(&p->sibling);
81 __this_cpu_dec(process_counts);
82 }
83 list_del_rcu(&p->thread_group);
84 list_del_rcu(&p->thread_node);
85}
86
87/*
88 * This function expects the tasklist_lock write-locked.
89 */
90static void __exit_signal(struct task_struct *tsk)
91{
92 struct signal_struct *sig = tsk->signal;
93 bool group_dead = thread_group_leader(tsk);
94 struct sighand_struct *sighand;
95 struct tty_struct *uninitialized_var(tty);
96 u64 utime, stime;
97
98 sighand = rcu_dereference_check(tsk->sighand,
99 lockdep_tasklist_lock_is_held());
100 spin_lock(&sighand->siglock);
101
102#ifdef CONFIG_POSIX_TIMERS
103 posix_cpu_timers_exit(tsk);
104 if (group_dead) {
105 posix_cpu_timers_exit_group(tsk);
106 } else {
107 /*
108 * This can only happen if the caller is de_thread().
109 * FIXME: this is the temporary hack, we should teach
110 * posix-cpu-timers to handle this case correctly.
111 */
112 if (unlikely(has_group_leader_pid(tsk)))
113 posix_cpu_timers_exit_group(tsk);
114 }
115#endif
116
117 if (group_dead) {
118 tty = sig->tty;
119 sig->tty = NULL;
120 } else {
121 /*
122 * If there is any task waiting for the group exit
123 * then notify it:
124 */
125 if (sig->notify_count > 0 && !--sig->notify_count)
126 wake_up_process(sig->group_exit_task);
127
128 if (tsk == sig->curr_target)
129 sig->curr_target = next_thread(tsk);
130 }
131
132 add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
133 sizeof(unsigned long long));
134
135 /*
136 * Accumulate here the counters for all threads as they die. We could
137 * skip the group leader because it is the last user of signal_struct,
138 * but we want to avoid the race with thread_group_cputime() which can
139 * see the empty ->thread_head list.
140 */
141 task_cputime(tsk, &utime, &stime);
142 write_seqlock(&sig->stats_lock);
143 sig->utime += utime;
144 sig->stime += stime;
145 sig->gtime += task_gtime(tsk);
146 sig->min_flt += tsk->min_flt;
147 sig->maj_flt += tsk->maj_flt;
148 sig->nvcsw += tsk->nvcsw;
149 sig->nivcsw += tsk->nivcsw;
150 sig->inblock += task_io_get_inblock(tsk);
151 sig->oublock += task_io_get_oublock(tsk);
152 task_io_accounting_add(&sig->ioac, &tsk->ioac);
153 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
154 sig->nr_threads--;
155 __unhash_process(tsk, group_dead);
156 write_sequnlock(&sig->stats_lock);
157
158 /*
159 * Do this under ->siglock, we can race with another thread
160 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
161 */
162 flush_sigqueue(&tsk->pending);
163 tsk->sighand = NULL;
164 spin_unlock(&sighand->siglock);
165
166 __cleanup_sighand(sighand);
167 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
168 if (group_dead) {
169 flush_sigqueue(&sig->shared_pending);
170 tty_kref_put(tty);
171 }
172}
173
174static void delayed_put_task_struct(struct rcu_head *rhp)
175{
176 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
177
178 perf_event_delayed_put(tsk);
179 trace_sched_process_free(tsk);
180 put_task_struct(tsk);
181}
182
183
184void release_task(struct task_struct *p)
185{
186 struct task_struct *leader;
187 int zap_leader;
188repeat:
189 /* don't need to get the RCU readlock here - the process is dead and
190 * can't be modifying its own credentials. But shut RCU-lockdep up */
191 rcu_read_lock();
192 atomic_dec(&__task_cred(p)->user->processes);
193 rcu_read_unlock();
194
195 proc_flush_task(p);
196
197 write_lock_irq(&tasklist_lock);
198 ptrace_release_task(p);
199 __exit_signal(p);
200
201 /*
202 * If we are the last non-leader member of the thread
203 * group, and the leader is zombie, then notify the
204 * group leader's parent process. (if it wants notification.)
205 */
206 zap_leader = 0;
207 leader = p->group_leader;
208 if (leader != p && thread_group_empty(leader)
209 && leader->exit_state == EXIT_ZOMBIE) {
210 /*
211 * If we were the last child thread and the leader has
212 * exited already, and the leader's parent ignores SIGCHLD,
213 * then we are the one who should release the leader.
214 */
215 zap_leader = do_notify_parent(leader, leader->exit_signal);
216 if (zap_leader)
217 leader->exit_state = EXIT_DEAD;
218 }
219
220 write_unlock_irq(&tasklist_lock);
221 release_thread(p);
222 call_rcu(&p->rcu, delayed_put_task_struct);
223
224 p = leader;
225 if (unlikely(zap_leader))
226 goto repeat;
227}
228
229/*
230 * Note that if this function returns a valid task_struct pointer (!NULL)
231 * task->usage must remain >0 for the duration of the RCU critical section.
232 */
233struct task_struct *task_rcu_dereference(struct task_struct **ptask)
234{
235 struct sighand_struct *sighand;
236 struct task_struct *task;
237
238 /*
239 * We need to verify that release_task() was not called and thus
240 * delayed_put_task_struct() can't run and drop the last reference
241 * before rcu_read_unlock(). We check task->sighand != NULL,
242 * but we can read the already freed and reused memory.
243 */
244retry:
245 task = rcu_dereference(*ptask);
246 if (!task)
247 return NULL;
248
249 probe_kernel_address(&task->sighand, sighand);
250
251 /*
252 * Pairs with atomic_dec_and_test() in put_task_struct(). If this task
253 * was already freed we can not miss the preceding update of this
254 * pointer.
255 */
256 smp_rmb();
257 if (unlikely(task != READ_ONCE(*ptask)))
258 goto retry;
259
260 /*
261 * We've re-checked that "task == *ptask", now we have two different
262 * cases:
263 *
264 * 1. This is actually the same task/task_struct. In this case
265 * sighand != NULL tells us it is still alive.
266 *
267 * 2. This is another task which got the same memory for task_struct.
268 * We can't know this of course, and we can not trust
269 * sighand != NULL.
270 *
271 * In this case we actually return a random value, but this is
272 * correct.
273 *
274 * If we return NULL - we can pretend that we actually noticed that
275 * *ptask was updated when the previous task has exited. Or pretend
276 * that probe_slab_address(&sighand) reads NULL.
277 *
278 * If we return the new task (because sighand is not NULL for any
279 * reason) - this is fine too. This (new) task can't go away before
280 * another gp pass.
281 *
282 * And note: We could even eliminate the false positive if re-read
283 * task->sighand once again to avoid the falsely NULL. But this case
284 * is very unlikely so we don't care.
285 */
286 if (!sighand)
287 return NULL;
288
289 return task;
290}
291
292void rcuwait_wake_up(struct rcuwait *w)
293{
294 struct task_struct *task;
295
296 rcu_read_lock();
297
298 /*
299 * Order condition vs @task, such that everything prior to the load
300 * of @task is visible. This is the condition as to why the user called
301 * rcuwait_trywake() in the first place. Pairs with set_current_state()
302 * barrier (A) in rcuwait_wait_event().
303 *
304 * WAIT WAKE
305 * [S] tsk = current [S] cond = true
306 * MB (A) MB (B)
307 * [L] cond [L] tsk
308 */
309 smp_rmb(); /* (B) */
310
311 /*
312 * Avoid using task_rcu_dereference() magic as long as we are careful,
313 * see comment in rcuwait_wait_event() regarding ->exit_state.
314 */
315 task = rcu_dereference(w->task);
316 if (task)
317 wake_up_process(task);
318 rcu_read_unlock();
319}
320
321/*
322 * Determine if a process group is "orphaned", according to the POSIX
323 * definition in 2.2.2.52. Orphaned process groups are not to be affected
324 * by terminal-generated stop signals. Newly orphaned process groups are
325 * to receive a SIGHUP and a SIGCONT.
326 *
327 * "I ask you, have you ever known what it is to be an orphan?"
328 */
329static int will_become_orphaned_pgrp(struct pid *pgrp,
330 struct task_struct *ignored_task)
331{
332 struct task_struct *p;
333
334 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
335 if ((p == ignored_task) ||
336 (p->exit_state && thread_group_empty(p)) ||
337 is_global_init(p->real_parent))
338 continue;
339
340 if (task_pgrp(p->real_parent) != pgrp &&
341 task_session(p->real_parent) == task_session(p))
342 return 0;
343 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
344
345 return 1;
346}
347
348int is_current_pgrp_orphaned(void)
349{
350 int retval;
351
352 read_lock(&tasklist_lock);
353 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
354 read_unlock(&tasklist_lock);
355
356 return retval;
357}
358
359static bool has_stopped_jobs(struct pid *pgrp)
360{
361 struct task_struct *p;
362
363 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
364 if (p->signal->flags & SIGNAL_STOP_STOPPED)
365 return true;
366 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
367
368 return false;
369}
370
371/*
372 * Check to see if any process groups have become orphaned as
373 * a result of our exiting, and if they have any stopped jobs,
374 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
375 */
376static void
377kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
378{
379 struct pid *pgrp = task_pgrp(tsk);
380 struct task_struct *ignored_task = tsk;
381
382 if (!parent)
383 /* exit: our father is in a different pgrp than
384 * we are and we were the only connection outside.
385 */
386 parent = tsk->real_parent;
387 else
388 /* reparent: our child is in a different pgrp than
389 * we are, and it was the only connection outside.
390 */
391 ignored_task = NULL;
392
393 if (task_pgrp(parent) != pgrp &&
394 task_session(parent) == task_session(tsk) &&
395 will_become_orphaned_pgrp(pgrp, ignored_task) &&
396 has_stopped_jobs(pgrp)) {
397 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
398 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
399 }
400}
401
402#ifdef CONFIG_MEMCG
403/*
404 * A task is exiting. If it owned this mm, find a new owner for the mm.
405 */
406void mm_update_next_owner(struct mm_struct *mm)
407{
408 struct task_struct *c, *g, *p = current;
409
410retry:
411 /*
412 * If the exiting or execing task is not the owner, it's
413 * someone else's problem.
414 */
415 if (mm->owner != p)
416 return;
417 /*
418 * The current owner is exiting/execing and there are no other
419 * candidates. Do not leave the mm pointing to a possibly
420 * freed task structure.
421 */
422 if (atomic_read(&mm->mm_users) <= 1) {
423 mm->owner = NULL;
424 return;
425 }
426
427 read_lock(&tasklist_lock);
428 /*
429 * Search in the children
430 */
431 list_for_each_entry(c, &p->children, sibling) {
432 if (c->mm == mm)
433 goto assign_new_owner;
434 }
435
436 /*
437 * Search in the siblings
438 */
439 list_for_each_entry(c, &p->real_parent->children, sibling) {
440 if (c->mm == mm)
441 goto assign_new_owner;
442 }
443
444 /*
445 * Search through everything else, we should not get here often.
446 */
447 for_each_process(g) {
448 if (g->flags & PF_KTHREAD)
449 continue;
450 for_each_thread(g, c) {
451 if (c->mm == mm)
452 goto assign_new_owner;
453 if (c->mm)
454 break;
455 }
456 }
457 read_unlock(&tasklist_lock);
458 /*
459 * We found no owner yet mm_users > 1: this implies that we are
460 * most likely racing with swapoff (try_to_unuse()) or /proc or
461 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
462 */
463 mm->owner = NULL;
464 return;
465
466assign_new_owner:
467 BUG_ON(c == p);
468 get_task_struct(c);
469 /*
470 * The task_lock protects c->mm from changing.
471 * We always want mm->owner->mm == mm
472 */
473 task_lock(c);
474 /*
475 * Delay read_unlock() till we have the task_lock()
476 * to ensure that c does not slip away underneath us
477 */
478 read_unlock(&tasklist_lock);
479 if (c->mm != mm) {
480 task_unlock(c);
481 put_task_struct(c);
482 goto retry;
483 }
484 mm->owner = c;
485 task_unlock(c);
486 put_task_struct(c);
487}
488#endif /* CONFIG_MEMCG */
489
490/*
491 * Turn us into a lazy TLB process if we
492 * aren't already..
493 */
494static void exit_mm(void)
495{
496 struct mm_struct *mm = current->mm;
497 struct core_state *core_state;
498
499 mm_release(current, mm);
500 if (!mm)
501 return;
502 sync_mm_rss(mm);
503 /*
504 * Serialize with any possible pending coredump.
505 * We must hold mmap_sem around checking core_state
506 * and clearing tsk->mm. The core-inducing thread
507 * will increment ->nr_threads for each thread in the
508 * group with ->mm != NULL.
509 */
510 down_read(&mm->mmap_sem);
511 core_state = mm->core_state;
512 if (core_state) {
513 struct core_thread self;
514
515 up_read(&mm->mmap_sem);
516
517 self.task = current;
518 self.next = xchg(&core_state->dumper.next, &self);
519 /*
520 * Implies mb(), the result of xchg() must be visible
521 * to core_state->dumper.
522 */
523 if (atomic_dec_and_test(&core_state->nr_threads))
524 complete(&core_state->startup);
525
526 for (;;) {
527 set_current_state(TASK_UNINTERRUPTIBLE);
528 if (!self.task) /* see coredump_finish() */
529 break;
530 freezable_schedule();
531 }
532 __set_current_state(TASK_RUNNING);
533 down_read(&mm->mmap_sem);
534 }
535 mmgrab(mm);
536 BUG_ON(mm != current->active_mm);
537 /* more a memory barrier than a real lock */
538 task_lock(current);
539 current->mm = NULL;
540 up_read(&mm->mmap_sem);
541 enter_lazy_tlb(mm, current);
542 task_unlock(current);
543 mm_update_next_owner(mm);
544 mmput(mm);
545 if (test_thread_flag(TIF_MEMDIE))
546 exit_oom_victim();
547}
548
549static struct task_struct *find_alive_thread(struct task_struct *p)
550{
551 struct task_struct *t;
552
553 for_each_thread(p, t) {
554 if (!(t->flags & PF_EXITING))
555 return t;
556 }
557 return NULL;
558}
559
560static struct task_struct *find_child_reaper(struct task_struct *father)
561 __releases(&tasklist_lock)
562 __acquires(&tasklist_lock)
563{
564 struct pid_namespace *pid_ns = task_active_pid_ns(father);
565 struct task_struct *reaper = pid_ns->child_reaper;
566
567 if (likely(reaper != father))
568 return reaper;
569
570 reaper = find_alive_thread(father);
571 if (reaper) {
572 pid_ns->child_reaper = reaper;
573 return reaper;
574 }
575
576 write_unlock_irq(&tasklist_lock);
577 if (unlikely(pid_ns == &init_pid_ns)) {
578 panic("Attempted to kill init! exitcode=0x%08x\n",
579 father->signal->group_exit_code ?: father->exit_code);
580 }
581 zap_pid_ns_processes(pid_ns);
582 write_lock_irq(&tasklist_lock);
583
584 return father;
585}
586
587/*
588 * When we die, we re-parent all our children, and try to:
589 * 1. give them to another thread in our thread group, if such a member exists
590 * 2. give it to the first ancestor process which prctl'd itself as a
591 * child_subreaper for its children (like a service manager)
592 * 3. give it to the init process (PID 1) in our pid namespace
593 */
594static struct task_struct *find_new_reaper(struct task_struct *father,
595 struct task_struct *child_reaper)
596{
597 struct task_struct *thread, *reaper;
598
599 thread = find_alive_thread(father);
600 if (thread)
601 return thread;
602
603 if (father->signal->has_child_subreaper) {
604 unsigned int ns_level = task_pid(father)->level;
605 /*
606 * Find the first ->is_child_subreaper ancestor in our pid_ns.
607 * We can't check reaper != child_reaper to ensure we do not
608 * cross the namespaces, the exiting parent could be injected
609 * by setns() + fork().
610 * We check pid->level, this is slightly more efficient than
611 * task_active_pid_ns(reaper) != task_active_pid_ns(father).
612 */
613 for (reaper = father->real_parent;
614 task_pid(reaper)->level == ns_level;
615 reaper = reaper->real_parent) {
616 if (reaper == &init_task)
617 break;
618 if (!reaper->signal->is_child_subreaper)
619 continue;
620 thread = find_alive_thread(reaper);
621 if (thread)
622 return thread;
623 }
624 }
625
626 return child_reaper;
627}
628
629/*
630* Any that need to be release_task'd are put on the @dead list.
631 */
632static void reparent_leader(struct task_struct *father, struct task_struct *p,
633 struct list_head *dead)
634{
635 if (unlikely(p->exit_state == EXIT_DEAD))
636 return;
637
638 /* We don't want people slaying init. */
639 p->exit_signal = SIGCHLD;
640
641 /* If it has exited notify the new parent about this child's death. */
642 if (!p->ptrace &&
643 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
644 if (do_notify_parent(p, p->exit_signal)) {
645 p->exit_state = EXIT_DEAD;
646 list_add(&p->ptrace_entry, dead);
647 }
648 }
649
650 kill_orphaned_pgrp(p, father);
651}
652
653/*
654 * This does two things:
655 *
656 * A. Make init inherit all the child processes
657 * B. Check to see if any process groups have become orphaned
658 * as a result of our exiting, and if they have any stopped
659 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
660 */
661static void forget_original_parent(struct task_struct *father,
662 struct list_head *dead)
663{
664 struct task_struct *p, *t, *reaper;
665
666 if (unlikely(!list_empty(&father->ptraced)))
667 exit_ptrace(father, dead);
668
669 /* Can drop and reacquire tasklist_lock */
670 reaper = find_child_reaper(father);
671 if (list_empty(&father->children))
672 return;
673
674 reaper = find_new_reaper(father, reaper);
675 list_for_each_entry(p, &father->children, sibling) {
676 for_each_thread(p, t) {
677 t->real_parent = reaper;
678 BUG_ON((!t->ptrace) != (t->parent == father));
679 if (likely(!t->ptrace))
680 t->parent = t->real_parent;
681 if (t->pdeath_signal)
682 group_send_sig_info(t->pdeath_signal,
683 SEND_SIG_NOINFO, t);
684 }
685 /*
686 * If this is a threaded reparent there is no need to
687 * notify anyone anything has happened.
688 */
689 if (!same_thread_group(reaper, father))
690 reparent_leader(father, p, dead);
691 }
692 list_splice_tail_init(&father->children, &reaper->children);
693}
694
695/*
696 * Send signals to all our closest relatives so that they know
697 * to properly mourn us..
698 */
699static void exit_notify(struct task_struct *tsk, int group_dead)
700{
701 bool autoreap;
702 struct task_struct *p, *n;
703 LIST_HEAD(dead);
704
705 write_lock_irq(&tasklist_lock);
706 forget_original_parent(tsk, &dead);
707
708 if (group_dead)
709 kill_orphaned_pgrp(tsk->group_leader, NULL);
710
711 if (unlikely(tsk->ptrace)) {
712 int sig = thread_group_leader(tsk) &&
713 thread_group_empty(tsk) &&
714 !ptrace_reparented(tsk) ?
715 tsk->exit_signal : SIGCHLD;
716 autoreap = do_notify_parent(tsk, sig);
717 } else if (thread_group_leader(tsk)) {
718 autoreap = thread_group_empty(tsk) &&
719 do_notify_parent(tsk, tsk->exit_signal);
720 } else {
721 autoreap = true;
722 }
723
724 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
725 if (tsk->exit_state == EXIT_DEAD)
726 list_add(&tsk->ptrace_entry, &dead);
727
728 /* mt-exec, de_thread() is waiting for group leader */
729 if (unlikely(tsk->signal->notify_count < 0))
730 wake_up_process(tsk->signal->group_exit_task);
731 write_unlock_irq(&tasklist_lock);
732
733 list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
734 list_del_init(&p->ptrace_entry);
735 release_task(p);
736 }
737}
738
739#ifdef CONFIG_DEBUG_STACK_USAGE
740static void check_stack_usage(void)
741{
742 static DEFINE_SPINLOCK(low_water_lock);
743 static int lowest_to_date = THREAD_SIZE;
744 unsigned long free;
745
746 free = stack_not_used(current);
747
748 if (free >= lowest_to_date)
749 return;
750
751 spin_lock(&low_water_lock);
752 if (free < lowest_to_date) {
753 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
754 current->comm, task_pid_nr(current), free);
755 lowest_to_date = free;
756 }
757 spin_unlock(&low_water_lock);
758}
759#else
760static inline void check_stack_usage(void) {}
761#endif
762
763void __noreturn do_exit(long code)
764{
765 struct task_struct *tsk = current;
766 int group_dead;
767
768 profile_task_exit(tsk);
769 kcov_task_exit(tsk);
770
771 WARN_ON(blk_needs_flush_plug(tsk));
772
773 if (unlikely(in_interrupt()))
774 panic("Aiee, killing interrupt handler!");
775 if (unlikely(!tsk->pid))
776 panic("Attempted to kill the idle task!");
777
778 /*
779 * If do_exit is called because this processes oopsed, it's possible
780 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
781 * continuing. Amongst other possible reasons, this is to prevent
782 * mm_release()->clear_child_tid() from writing to a user-controlled
783 * kernel address.
784 */
785 set_fs(USER_DS);
786
787 ptrace_event(PTRACE_EVENT_EXIT, code);
788
789 validate_creds_for_do_exit(tsk);
790
791 /*
792 * We're taking recursive faults here in do_exit. Safest is to just
793 * leave this task alone and wait for reboot.
794 */
795 if (unlikely(tsk->flags & PF_EXITING)) {
796 pr_alert("Fixing recursive fault but reboot is needed!\n");
797 /*
798 * We can do this unlocked here. The futex code uses
799 * this flag just to verify whether the pi state
800 * cleanup has been done or not. In the worst case it
801 * loops once more. We pretend that the cleanup was
802 * done as there is no way to return. Either the
803 * OWNER_DIED bit is set by now or we push the blocked
804 * task into the wait for ever nirwana as well.
805 */
806 tsk->flags |= PF_EXITPIDONE;
807 set_current_state(TASK_UNINTERRUPTIBLE);
808 schedule();
809 }
810
811 exit_signals(tsk); /* sets PF_EXITING */
812 /*
813 * Ensure that all new tsk->pi_lock acquisitions must observe
814 * PF_EXITING. Serializes against futex.c:attach_to_pi_owner().
815 */
816 smp_mb();
817 /*
818 * Ensure that we must observe the pi_state in exit_mm() ->
819 * mm_release() -> exit_pi_state_list().
820 */
821 raw_spin_lock_irq(&tsk->pi_lock);
822 raw_spin_unlock_irq(&tsk->pi_lock);
823
824 if (unlikely(in_atomic())) {
825 pr_info("note: %s[%d] exited with preempt_count %d\n",
826 current->comm, task_pid_nr(current),
827 preempt_count());
828 preempt_count_set(PREEMPT_ENABLED);
829 }
830
831 /* sync mm's RSS info before statistics gathering */
832 if (tsk->mm)
833 sync_mm_rss(tsk->mm);
834 acct_update_integrals(tsk);
835 group_dead = atomic_dec_and_test(&tsk->signal->live);
836 if (group_dead) {
837#ifdef CONFIG_POSIX_TIMERS
838 hrtimer_cancel(&tsk->signal->real_timer);
839 exit_itimers(tsk->signal);
840#endif
841 if (tsk->mm)
842 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
843 }
844 acct_collect(code, group_dead);
845 if (group_dead)
846 tty_audit_exit();
847 audit_free(tsk);
848
849 tsk->exit_code = code;
850 taskstats_exit(tsk, group_dead);
851
852 exit_mm();
853
854 if (group_dead)
855 acct_process();
856 trace_sched_process_exit(tsk);
857
858 exit_sem(tsk);
859 exit_shm(tsk);
860 exit_files(tsk);
861 exit_fs(tsk);
862 if (group_dead)
863 disassociate_ctty(1);
864 exit_task_namespaces(tsk);
865 exit_task_work(tsk);
866 exit_thread(tsk);
867
868 /*
869 * Flush inherited counters to the parent - before the parent
870 * gets woken up by child-exit notifications.
871 *
872 * because of cgroup mode, must be called before cgroup_exit()
873 */
874 perf_event_exit_task(tsk);
875
876 sched_autogroup_exit_task(tsk);
877 cgroup_exit(tsk);
878
879 /*
880 * FIXME: do that only when needed, using sched_exit tracepoint
881 */
882 flush_ptrace_hw_breakpoint(tsk);
883
884 exit_tasks_rcu_start();
885 exit_notify(tsk, group_dead);
886 proc_exit_connector(tsk);
887 mpol_put_task_policy(tsk);
888#ifdef CONFIG_FUTEX
889 if (unlikely(current->pi_state_cache))
890 kfree(current->pi_state_cache);
891#endif
892 /*
893 * Make sure we are holding no locks:
894 */
895 debug_check_no_locks_held();
896 /*
897 * We can do this unlocked here. The futex code uses this flag
898 * just to verify whether the pi state cleanup has been done
899 * or not. In the worst case it loops once more.
900 */
901 tsk->flags |= PF_EXITPIDONE;
902
903 if (tsk->io_context)
904 exit_io_context(tsk);
905
906 if (tsk->splice_pipe)
907 free_pipe_info(tsk->splice_pipe);
908
909 if (tsk->task_frag.page)
910 put_page(tsk->task_frag.page);
911
912 validate_creds_for_do_exit(tsk);
913
914 check_stack_usage();
915 preempt_disable();
916 if (tsk->nr_dirtied)
917 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
918 exit_rcu();
919 exit_tasks_rcu_finish();
920
921 lockdep_free_task(tsk);
922 do_task_dead();
923}
924EXPORT_SYMBOL_GPL(do_exit);
925
926void complete_and_exit(struct completion *comp, long code)
927{
928 if (comp)
929 complete(comp);
930
931 do_exit(code);
932}
933EXPORT_SYMBOL(complete_and_exit);
934
935SYSCALL_DEFINE1(exit, int, error_code)
936{
937 do_exit((error_code&0xff)<<8);
938}
939
940/*
941 * Take down every thread in the group. This is called by fatal signals
942 * as well as by sys_exit_group (below).
943 */
944void
945do_group_exit(int exit_code)
946{
947 struct signal_struct *sig = current->signal;
948
949 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
950
951 if (signal_group_exit(sig))
952 exit_code = sig->group_exit_code;
953 else if (!thread_group_empty(current)) {
954 struct sighand_struct *const sighand = current->sighand;
955
956 spin_lock_irq(&sighand->siglock);
957 if (signal_group_exit(sig))
958 /* Another thread got here before we took the lock. */
959 exit_code = sig->group_exit_code;
960 else {
961 sig->group_exit_code = exit_code;
962 sig->flags = SIGNAL_GROUP_EXIT;
963 zap_other_threads(current);
964 }
965 spin_unlock_irq(&sighand->siglock);
966 }
967
968 do_exit(exit_code);
969 /* NOTREACHED */
970}
971
972/*
973 * this kills every thread in the thread group. Note that any externally
974 * wait4()-ing process will get the correct exit code - even if this
975 * thread is not the thread group leader.
976 */
977SYSCALL_DEFINE1(exit_group, int, error_code)
978{
979 do_group_exit((error_code & 0xff) << 8);
980 /* NOTREACHED */
981 return 0;
982}
983
984struct waitid_info {
985 pid_t pid;
986 uid_t uid;
987 int status;
988 int cause;
989};
990
991struct wait_opts {
992 enum pid_type wo_type;
993 int wo_flags;
994 struct pid *wo_pid;
995
996 struct waitid_info *wo_info;
997 int wo_stat;
998 struct rusage *wo_rusage;
999
1000 wait_queue_entry_t child_wait;
1001 int notask_error;
1002};
1003
1004static inline
1005struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
1006{
1007 if (type != PIDTYPE_PID)
1008 task = task->group_leader;
1009 return task->pids[type].pid;
1010}
1011
1012static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
1013{
1014 return wo->wo_type == PIDTYPE_MAX ||
1015 task_pid_type(p, wo->wo_type) == wo->wo_pid;
1016}
1017
1018static int
1019eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
1020{
1021 if (!eligible_pid(wo, p))
1022 return 0;
1023
1024 /*
1025 * Wait for all children (clone and not) if __WALL is set or
1026 * if it is traced by us.
1027 */
1028 if (ptrace || (wo->wo_flags & __WALL))
1029 return 1;
1030
1031 /*
1032 * Otherwise, wait for clone children *only* if __WCLONE is set;
1033 * otherwise, wait for non-clone children *only*.
1034 *
1035 * Note: a "clone" child here is one that reports to its parent
1036 * using a signal other than SIGCHLD, or a non-leader thread which
1037 * we can only see if it is traced by us.
1038 */
1039 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
1040 return 0;
1041
1042 return 1;
1043}
1044
1045/*
1046 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1047 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1048 * the lock and this task is uninteresting. If we return nonzero, we have
1049 * released the lock and the system call should return.
1050 */
1051static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1052{
1053 int state, status;
1054 pid_t pid = task_pid_vnr(p);
1055 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1056 struct waitid_info *infop;
1057
1058 if (!likely(wo->wo_flags & WEXITED))
1059 return 0;
1060
1061 if (unlikely(wo->wo_flags & WNOWAIT)) {
1062 status = p->exit_code;
1063 get_task_struct(p);
1064 read_unlock(&tasklist_lock);
1065 sched_annotate_sleep();
1066 if (wo->wo_rusage)
1067 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1068 put_task_struct(p);
1069 goto out_info;
1070 }
1071 /*
1072 * Move the task's state to DEAD/TRACE, only one thread can do this.
1073 */
1074 state = (ptrace_reparented(p) && thread_group_leader(p)) ?
1075 EXIT_TRACE : EXIT_DEAD;
1076 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1077 return 0;
1078 /*
1079 * We own this thread, nobody else can reap it.
1080 */
1081 read_unlock(&tasklist_lock);
1082 sched_annotate_sleep();
1083
1084 /*
1085 * Check thread_group_leader() to exclude the traced sub-threads.
1086 */
1087 if (state == EXIT_DEAD && thread_group_leader(p)) {
1088 struct signal_struct *sig = p->signal;
1089 struct signal_struct *psig = current->signal;
1090 unsigned long maxrss;
1091 u64 tgutime, tgstime;
1092
1093 /*
1094 * The resource counters for the group leader are in its
1095 * own task_struct. Those for dead threads in the group
1096 * are in its signal_struct, as are those for the child
1097 * processes it has previously reaped. All these
1098 * accumulate in the parent's signal_struct c* fields.
1099 *
1100 * We don't bother to take a lock here to protect these
1101 * p->signal fields because the whole thread group is dead
1102 * and nobody can change them.
1103 *
1104 * psig->stats_lock also protects us from our sub-theads
1105 * which can reap other children at the same time. Until
1106 * we change k_getrusage()-like users to rely on this lock
1107 * we have to take ->siglock as well.
1108 *
1109 * We use thread_group_cputime_adjusted() to get times for
1110 * the thread group, which consolidates times for all threads
1111 * in the group including the group leader.
1112 */
1113 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1114 spin_lock_irq(¤t->sighand->siglock);
1115 write_seqlock(&psig->stats_lock);
1116 psig->cutime += tgutime + sig->cutime;
1117 psig->cstime += tgstime + sig->cstime;
1118 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1119 psig->cmin_flt +=
1120 p->min_flt + sig->min_flt + sig->cmin_flt;
1121 psig->cmaj_flt +=
1122 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1123 psig->cnvcsw +=
1124 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1125 psig->cnivcsw +=
1126 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1127 psig->cinblock +=
1128 task_io_get_inblock(p) +
1129 sig->inblock + sig->cinblock;
1130 psig->coublock +=
1131 task_io_get_oublock(p) +
1132 sig->oublock + sig->coublock;
1133 maxrss = max(sig->maxrss, sig->cmaxrss);
1134 if (psig->cmaxrss < maxrss)
1135 psig->cmaxrss = maxrss;
1136 task_io_accounting_add(&psig->ioac, &p->ioac);
1137 task_io_accounting_add(&psig->ioac, &sig->ioac);
1138 write_sequnlock(&psig->stats_lock);
1139 spin_unlock_irq(¤t->sighand->siglock);
1140 }
1141
1142 if (wo->wo_rusage)
1143 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1144 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1145 ? p->signal->group_exit_code : p->exit_code;
1146 wo->wo_stat = status;
1147
1148 if (state == EXIT_TRACE) {
1149 write_lock_irq(&tasklist_lock);
1150 /* We dropped tasklist, ptracer could die and untrace */
1151 ptrace_unlink(p);
1152
1153 /* If parent wants a zombie, don't release it now */
1154 state = EXIT_ZOMBIE;
1155 if (do_notify_parent(p, p->exit_signal))
1156 state = EXIT_DEAD;
1157 p->exit_state = state;
1158 write_unlock_irq(&tasklist_lock);
1159 }
1160 if (state == EXIT_DEAD)
1161 release_task(p);
1162
1163out_info:
1164 infop = wo->wo_info;
1165 if (infop) {
1166 if ((status & 0x7f) == 0) {
1167 infop->cause = CLD_EXITED;
1168 infop->status = status >> 8;
1169 } else {
1170 infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1171 infop->status = status & 0x7f;
1172 }
1173 infop->pid = pid;
1174 infop->uid = uid;
1175 }
1176
1177 return pid;
1178}
1179
1180static int *task_stopped_code(struct task_struct *p, bool ptrace)
1181{
1182 if (ptrace) {
1183 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING))
1184 return &p->exit_code;
1185 } else {
1186 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1187 return &p->signal->group_exit_code;
1188 }
1189 return NULL;
1190}
1191
1192/**
1193 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1194 * @wo: wait options
1195 * @ptrace: is the wait for ptrace
1196 * @p: task to wait for
1197 *
1198 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1199 *
1200 * CONTEXT:
1201 * read_lock(&tasklist_lock), which is released if return value is
1202 * non-zero. Also, grabs and releases @p->sighand->siglock.
1203 *
1204 * RETURNS:
1205 * 0 if wait condition didn't exist and search for other wait conditions
1206 * should continue. Non-zero return, -errno on failure and @p's pid on
1207 * success, implies that tasklist_lock is released and wait condition
1208 * search should terminate.
1209 */
1210static int wait_task_stopped(struct wait_opts *wo,
1211 int ptrace, struct task_struct *p)
1212{
1213 struct waitid_info *infop;
1214 int exit_code, *p_code, why;
1215 uid_t uid = 0; /* unneeded, required by compiler */
1216 pid_t pid;
1217
1218 /*
1219 * Traditionally we see ptrace'd stopped tasks regardless of options.
1220 */
1221 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1222 return 0;
1223
1224 if (!task_stopped_code(p, ptrace))
1225 return 0;
1226
1227 exit_code = 0;
1228 spin_lock_irq(&p->sighand->siglock);
1229
1230 p_code = task_stopped_code(p, ptrace);
1231 if (unlikely(!p_code))
1232 goto unlock_sig;
1233
1234 exit_code = *p_code;
1235 if (!exit_code)
1236 goto unlock_sig;
1237
1238 if (!unlikely(wo->wo_flags & WNOWAIT))
1239 *p_code = 0;
1240
1241 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1242unlock_sig:
1243 spin_unlock_irq(&p->sighand->siglock);
1244 if (!exit_code)
1245 return 0;
1246
1247 /*
1248 * Now we are pretty sure this task is interesting.
1249 * Make sure it doesn't get reaped out from under us while we
1250 * give up the lock and then examine it below. We don't want to
1251 * keep holding onto the tasklist_lock while we call getrusage and
1252 * possibly take page faults for user memory.
1253 */
1254 get_task_struct(p);
1255 pid = task_pid_vnr(p);
1256 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1257 read_unlock(&tasklist_lock);
1258 sched_annotate_sleep();
1259 if (wo->wo_rusage)
1260 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1261 put_task_struct(p);
1262
1263 if (likely(!(wo->wo_flags & WNOWAIT)))
1264 wo->wo_stat = (exit_code << 8) | 0x7f;
1265
1266 infop = wo->wo_info;
1267 if (infop) {
1268 infop->cause = why;
1269 infop->status = exit_code;
1270 infop->pid = pid;
1271 infop->uid = uid;
1272 }
1273 return pid;
1274}
1275
1276/*
1277 * Handle do_wait work for one task in a live, non-stopped state.
1278 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1279 * the lock and this task is uninteresting. If we return nonzero, we have
1280 * released the lock and the system call should return.
1281 */
1282static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1283{
1284 struct waitid_info *infop;
1285 pid_t pid;
1286 uid_t uid;
1287
1288 if (!unlikely(wo->wo_flags & WCONTINUED))
1289 return 0;
1290
1291 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1292 return 0;
1293
1294 spin_lock_irq(&p->sighand->siglock);
1295 /* Re-check with the lock held. */
1296 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1297 spin_unlock_irq(&p->sighand->siglock);
1298 return 0;
1299 }
1300 if (!unlikely(wo->wo_flags & WNOWAIT))
1301 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1302 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1303 spin_unlock_irq(&p->sighand->siglock);
1304
1305 pid = task_pid_vnr(p);
1306 get_task_struct(p);
1307 read_unlock(&tasklist_lock);
1308 sched_annotate_sleep();
1309 if (wo->wo_rusage)
1310 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1311 put_task_struct(p);
1312
1313 infop = wo->wo_info;
1314 if (!infop) {
1315 wo->wo_stat = 0xffff;
1316 } else {
1317 infop->cause = CLD_CONTINUED;
1318 infop->pid = pid;
1319 infop->uid = uid;
1320 infop->status = SIGCONT;
1321 }
1322 return pid;
1323}
1324
1325/*
1326 * Consider @p for a wait by @parent.
1327 *
1328 * -ECHILD should be in ->notask_error before the first call.
1329 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1330 * Returns zero if the search for a child should continue;
1331 * then ->notask_error is 0 if @p is an eligible child,
1332 * or still -ECHILD.
1333 */
1334static int wait_consider_task(struct wait_opts *wo, int ptrace,
1335 struct task_struct *p)
1336{
1337 /*
1338 * We can race with wait_task_zombie() from another thread.
1339 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1340 * can't confuse the checks below.
1341 */
1342 int exit_state = READ_ONCE(p->exit_state);
1343 int ret;
1344
1345 if (unlikely(exit_state == EXIT_DEAD))
1346 return 0;
1347
1348 ret = eligible_child(wo, ptrace, p);
1349 if (!ret)
1350 return ret;
1351
1352 if (unlikely(exit_state == EXIT_TRACE)) {
1353 /*
1354 * ptrace == 0 means we are the natural parent. In this case
1355 * we should clear notask_error, debugger will notify us.
1356 */
1357 if (likely(!ptrace))
1358 wo->notask_error = 0;
1359 return 0;
1360 }
1361
1362 if (likely(!ptrace) && unlikely(p->ptrace)) {
1363 /*
1364 * If it is traced by its real parent's group, just pretend
1365 * the caller is ptrace_do_wait() and reap this child if it
1366 * is zombie.
1367 *
1368 * This also hides group stop state from real parent; otherwise
1369 * a single stop can be reported twice as group and ptrace stop.
1370 * If a ptracer wants to distinguish these two events for its
1371 * own children it should create a separate process which takes
1372 * the role of real parent.
1373 */
1374 if (!ptrace_reparented(p))
1375 ptrace = 1;
1376 }
1377
1378 /* slay zombie? */
1379 if (exit_state == EXIT_ZOMBIE) {
1380 /* we don't reap group leaders with subthreads */
1381 if (!delay_group_leader(p)) {
1382 /*
1383 * A zombie ptracee is only visible to its ptracer.
1384 * Notification and reaping will be cascaded to the
1385 * real parent when the ptracer detaches.
1386 */
1387 if (unlikely(ptrace) || likely(!p->ptrace))
1388 return wait_task_zombie(wo, p);
1389 }
1390
1391 /*
1392 * Allow access to stopped/continued state via zombie by
1393 * falling through. Clearing of notask_error is complex.
1394 *
1395 * When !@ptrace:
1396 *
1397 * If WEXITED is set, notask_error should naturally be
1398 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1399 * so, if there are live subthreads, there are events to
1400 * wait for. If all subthreads are dead, it's still safe
1401 * to clear - this function will be called again in finite
1402 * amount time once all the subthreads are released and
1403 * will then return without clearing.
1404 *
1405 * When @ptrace:
1406 *
1407 * Stopped state is per-task and thus can't change once the
1408 * target task dies. Only continued and exited can happen.
1409 * Clear notask_error if WCONTINUED | WEXITED.
1410 */
1411 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1412 wo->notask_error = 0;
1413 } else {
1414 /*
1415 * @p is alive and it's gonna stop, continue or exit, so
1416 * there always is something to wait for.
1417 */
1418 wo->notask_error = 0;
1419 }
1420
1421 /*
1422 * Wait for stopped. Depending on @ptrace, different stopped state
1423 * is used and the two don't interact with each other.
1424 */
1425 ret = wait_task_stopped(wo, ptrace, p);
1426 if (ret)
1427 return ret;
1428
1429 /*
1430 * Wait for continued. There's only one continued state and the
1431 * ptracer can consume it which can confuse the real parent. Don't
1432 * use WCONTINUED from ptracer. You don't need or want it.
1433 */
1434 return wait_task_continued(wo, p);
1435}
1436
1437/*
1438 * Do the work of do_wait() for one thread in the group, @tsk.
1439 *
1440 * -ECHILD should be in ->notask_error before the first call.
1441 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1442 * Returns zero if the search for a child should continue; then
1443 * ->notask_error is 0 if there were any eligible children,
1444 * or still -ECHILD.
1445 */
1446static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1447{
1448 struct task_struct *p;
1449
1450 list_for_each_entry(p, &tsk->children, sibling) {
1451 int ret = wait_consider_task(wo, 0, p);
1452
1453 if (ret)
1454 return ret;
1455 }
1456
1457 return 0;
1458}
1459
1460static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1461{
1462 struct task_struct *p;
1463
1464 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1465 int ret = wait_consider_task(wo, 1, p);
1466
1467 if (ret)
1468 return ret;
1469 }
1470
1471 return 0;
1472}
1473
1474static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode,
1475 int sync, void *key)
1476{
1477 struct wait_opts *wo = container_of(wait, struct wait_opts,
1478 child_wait);
1479 struct task_struct *p = key;
1480
1481 if (!eligible_pid(wo, p))
1482 return 0;
1483
1484 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1485 return 0;
1486
1487 return default_wake_function(wait, mode, sync, key);
1488}
1489
1490void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1491{
1492 __wake_up_sync_key(&parent->signal->wait_chldexit,
1493 TASK_INTERRUPTIBLE, 1, p);
1494}
1495
1496static long do_wait(struct wait_opts *wo)
1497{
1498 struct task_struct *tsk;
1499 int retval;
1500
1501 trace_sched_process_wait(wo->wo_pid);
1502
1503 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1504 wo->child_wait.private = current;
1505 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1506repeat:
1507 /*
1508 * If there is nothing that can match our criteria, just get out.
1509 * We will clear ->notask_error to zero if we see any child that
1510 * might later match our criteria, even if we are not able to reap
1511 * it yet.
1512 */
1513 wo->notask_error = -ECHILD;
1514 if ((wo->wo_type < PIDTYPE_MAX) &&
1515 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1516 goto notask;
1517
1518 set_current_state(TASK_INTERRUPTIBLE);
1519 read_lock(&tasklist_lock);
1520 tsk = current;
1521 do {
1522 retval = do_wait_thread(wo, tsk);
1523 if (retval)
1524 goto end;
1525
1526 retval = ptrace_do_wait(wo, tsk);
1527 if (retval)
1528 goto end;
1529
1530 if (wo->wo_flags & __WNOTHREAD)
1531 break;
1532 } while_each_thread(current, tsk);
1533 read_unlock(&tasklist_lock);
1534
1535notask:
1536 retval = wo->notask_error;
1537 if (!retval && !(wo->wo_flags & WNOHANG)) {
1538 retval = -ERESTARTSYS;
1539 if (!signal_pending(current)) {
1540 schedule();
1541 goto repeat;
1542 }
1543 }
1544end:
1545 __set_current_state(TASK_RUNNING);
1546 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1547 return retval;
1548}
1549
1550static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
1551 int options, struct rusage *ru)
1552{
1553 struct wait_opts wo;
1554 struct pid *pid = NULL;
1555 enum pid_type type;
1556 long ret;
1557
1558 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
1559 __WNOTHREAD|__WCLONE|__WALL))
1560 return -EINVAL;
1561 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1562 return -EINVAL;
1563
1564 switch (which) {
1565 case P_ALL:
1566 type = PIDTYPE_MAX;
1567 break;
1568 case P_PID:
1569 type = PIDTYPE_PID;
1570 if (upid <= 0)
1571 return -EINVAL;
1572 break;
1573 case P_PGID:
1574 type = PIDTYPE_PGID;
1575 if (upid <= 0)
1576 return -EINVAL;
1577 break;
1578 default:
1579 return -EINVAL;
1580 }
1581
1582 if (type < PIDTYPE_MAX)
1583 pid = find_get_pid(upid);
1584
1585 wo.wo_type = type;
1586 wo.wo_pid = pid;
1587 wo.wo_flags = options;
1588 wo.wo_info = infop;
1589 wo.wo_rusage = ru;
1590 ret = do_wait(&wo);
1591
1592 put_pid(pid);
1593 return ret;
1594}
1595
1596SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1597 infop, int, options, struct rusage __user *, ru)
1598{
1599 struct rusage r;
1600 struct waitid_info info = {.status = 0};
1601 long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
1602 int signo = 0;
1603
1604 if (err > 0) {
1605 signo = SIGCHLD;
1606 err = 0;
1607 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1608 return -EFAULT;
1609 }
1610 if (!infop)
1611 return err;
1612
1613 if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop)))
1614 return -EFAULT;
1615
1616 user_access_begin();
1617 unsafe_put_user(signo, &infop->si_signo, Efault);
1618 unsafe_put_user(0, &infop->si_errno, Efault);
1619 unsafe_put_user(info.cause, &infop->si_code, Efault);
1620 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1621 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1622 unsafe_put_user(info.status, &infop->si_status, Efault);
1623 user_access_end();
1624 return err;
1625Efault:
1626 user_access_end();
1627 return -EFAULT;
1628}
1629
1630long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
1631 struct rusage *ru)
1632{
1633 struct wait_opts wo;
1634 struct pid *pid = NULL;
1635 enum pid_type type;
1636 long ret;
1637
1638 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1639 __WNOTHREAD|__WCLONE|__WALL))
1640 return -EINVAL;
1641
1642 /* -INT_MIN is not defined */
1643 if (upid == INT_MIN)
1644 return -ESRCH;
1645
1646 if (upid == -1)
1647 type = PIDTYPE_MAX;
1648 else if (upid < 0) {
1649 type = PIDTYPE_PGID;
1650 pid = find_get_pid(-upid);
1651 } else if (upid == 0) {
1652 type = PIDTYPE_PGID;
1653 pid = get_task_pid(current, PIDTYPE_PGID);
1654 } else /* upid > 0 */ {
1655 type = PIDTYPE_PID;
1656 pid = find_get_pid(upid);
1657 }
1658
1659 wo.wo_type = type;
1660 wo.wo_pid = pid;
1661 wo.wo_flags = options | WEXITED;
1662 wo.wo_info = NULL;
1663 wo.wo_stat = 0;
1664 wo.wo_rusage = ru;
1665 ret = do_wait(&wo);
1666 put_pid(pid);
1667 if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
1668 ret = -EFAULT;
1669
1670 return ret;
1671}
1672
1673SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1674 int, options, struct rusage __user *, ru)
1675{
1676 struct rusage r;
1677 long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL);
1678
1679 if (err > 0) {
1680 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1681 return -EFAULT;
1682 }
1683 return err;
1684}
1685
1686#ifdef __ARCH_WANT_SYS_WAITPID
1687
1688/*
1689 * sys_waitpid() remains for compatibility. waitpid() should be
1690 * implemented by calling sys_wait4() from libc.a.
1691 */
1692SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1693{
1694 return kernel_wait4(pid, stat_addr, options, NULL);
1695}
1696
1697#endif
1698
1699#ifdef CONFIG_COMPAT
1700COMPAT_SYSCALL_DEFINE4(wait4,
1701 compat_pid_t, pid,
1702 compat_uint_t __user *, stat_addr,
1703 int, options,
1704 struct compat_rusage __user *, ru)
1705{
1706 struct rusage r;
1707 long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL);
1708 if (err > 0) {
1709 if (ru && put_compat_rusage(&r, ru))
1710 return -EFAULT;
1711 }
1712 return err;
1713}
1714
1715COMPAT_SYSCALL_DEFINE5(waitid,
1716 int, which, compat_pid_t, pid,
1717 struct compat_siginfo __user *, infop, int, options,
1718 struct compat_rusage __user *, uru)
1719{
1720 struct rusage ru;
1721 struct waitid_info info = {.status = 0};
1722 long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);
1723 int signo = 0;
1724 if (err > 0) {
1725 signo = SIGCHLD;
1726 err = 0;
1727 if (uru) {
1728 /* kernel_waitid() overwrites everything in ru */
1729 if (COMPAT_USE_64BIT_TIME)
1730 err = copy_to_user(uru, &ru, sizeof(ru));
1731 else
1732 err = put_compat_rusage(&ru, uru);
1733 if (err)
1734 return -EFAULT;
1735 }
1736 }
1737
1738 if (!infop)
1739 return err;
1740
1741 if (!access_ok(VERIFY_WRITE, infop, sizeof(*infop)))
1742 return -EFAULT;
1743
1744 user_access_begin();
1745 unsafe_put_user(signo, &infop->si_signo, Efault);
1746 unsafe_put_user(0, &infop->si_errno, Efault);
1747 unsafe_put_user(info.cause, &infop->si_code, Efault);
1748 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1749 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1750 unsafe_put_user(info.status, &infop->si_status, Efault);
1751 user_access_end();
1752 return err;
1753Efault:
1754 user_access_end();
1755 return -EFAULT;
1756}
1757#endif
1758
1759__weak void abort(void)
1760{
1761 BUG();
1762
1763 /* if that doesn't kill us, halt */
1764 panic("Oops failed to kill thread");
1765}
1766EXPORT_SYMBOL(abort);
1/*
2 * linux/kernel/exit.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7#include <linux/mm.h>
8#include <linux/slab.h>
9#include <linux/interrupt.h>
10#include <linux/module.h>
11#include <linux/capability.h>
12#include <linux/completion.h>
13#include <linux/personality.h>
14#include <linux/tty.h>
15#include <linux/iocontext.h>
16#include <linux/key.h>
17#include <linux/security.h>
18#include <linux/cpu.h>
19#include <linux/acct.h>
20#include <linux/tsacct_kern.h>
21#include <linux/file.h>
22#include <linux/fdtable.h>
23#include <linux/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
55#include <asm/uaccess.h>
56#include <asm/unistd.h>
57#include <asm/pgtable.h>
58#include <asm/mmu_context.h>
59
60static void exit_mm(struct task_struct * tsk);
61
62static void __unhash_process(struct task_struct *p, bool group_dead)
63{
64 nr_threads--;
65 detach_pid(p, PIDTYPE_PID);
66 if (group_dead) {
67 detach_pid(p, PIDTYPE_PGID);
68 detach_pid(p, PIDTYPE_SID);
69
70 list_del_rcu(&p->tasks);
71 list_del_init(&p->sibling);
72 __this_cpu_dec(process_counts);
73 }
74 list_del_rcu(&p->thread_group);
75}
76
77/*
78 * This function expects the tasklist_lock write-locked.
79 */
80static void __exit_signal(struct task_struct *tsk)
81{
82 struct signal_struct *sig = tsk->signal;
83 bool group_dead = thread_group_leader(tsk);
84 struct sighand_struct *sighand;
85 struct tty_struct *uninitialized_var(tty);
86
87 sighand = rcu_dereference_check(tsk->sighand,
88 lockdep_tasklist_lock_is_held());
89 spin_lock(&sighand->siglock);
90
91 posix_cpu_timers_exit(tsk);
92 if (group_dead) {
93 posix_cpu_timers_exit_group(tsk);
94 tty = sig->tty;
95 sig->tty = NULL;
96 } else {
97 /*
98 * This can only happen if the caller is de_thread().
99 * FIXME: this is the temporary hack, we should teach
100 * posix-cpu-timers to handle this case correctly.
101 */
102 if (unlikely(has_group_leader_pid(tsk)))
103 posix_cpu_timers_exit_group(tsk);
104
105 /*
106 * If there is any task waiting for the group exit
107 * then notify it:
108 */
109 if (sig->notify_count > 0 && !--sig->notify_count)
110 wake_up_process(sig->group_exit_task);
111
112 if (tsk == sig->curr_target)
113 sig->curr_target = next_thread(tsk);
114 /*
115 * Accumulate here the counters for all threads but the
116 * group leader as they die, so they can be added into
117 * the process-wide totals when those are taken.
118 * The group leader stays around as a zombie as long
119 * as there are other threads. When it gets reaped,
120 * the exit.c code will add its counts into these totals.
121 * We won't ever get here for the group leader, since it
122 * will have been the last reference on the signal_struct.
123 */
124 sig->utime = cputime_add(sig->utime, tsk->utime);
125 sig->stime = cputime_add(sig->stime, tsk->stime);
126 sig->gtime = cputime_add(sig->gtime, tsk->gtime);
127 sig->min_flt += tsk->min_flt;
128 sig->maj_flt += tsk->maj_flt;
129 sig->nvcsw += tsk->nvcsw;
130 sig->nivcsw += tsk->nivcsw;
131 sig->inblock += task_io_get_inblock(tsk);
132 sig->oublock += task_io_get_oublock(tsk);
133 task_io_accounting_add(&sig->ioac, &tsk->ioac);
134 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
135 }
136
137 sig->nr_threads--;
138 __unhash_process(tsk, group_dead);
139
140 /*
141 * Do this under ->siglock, we can race with another thread
142 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
143 */
144 flush_sigqueue(&tsk->pending);
145 tsk->sighand = NULL;
146 spin_unlock(&sighand->siglock);
147
148 __cleanup_sighand(sighand);
149 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
150 if (group_dead) {
151 flush_sigqueue(&sig->shared_pending);
152 tty_kref_put(tty);
153 }
154}
155
156static void delayed_put_task_struct(struct rcu_head *rhp)
157{
158 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
159
160 perf_event_delayed_put(tsk);
161 trace_sched_process_free(tsk);
162 put_task_struct(tsk);
163}
164
165
166void release_task(struct task_struct * p)
167{
168 struct task_struct *leader;
169 int zap_leader;
170repeat:
171 /* don't need to get the RCU readlock here - the process is dead and
172 * can't be modifying its own credentials. But shut RCU-lockdep up */
173 rcu_read_lock();
174 atomic_dec(&__task_cred(p)->user->processes);
175 rcu_read_unlock();
176
177 proc_flush_task(p);
178
179 write_lock_irq(&tasklist_lock);
180 ptrace_release_task(p);
181 __exit_signal(p);
182
183 /*
184 * If we are the last non-leader member of the thread
185 * group, and the leader is zombie, then notify the
186 * group leader's parent process. (if it wants notification.)
187 */
188 zap_leader = 0;
189 leader = p->group_leader;
190 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
191 /*
192 * If we were the last child thread and the leader has
193 * exited already, and the leader's parent ignores SIGCHLD,
194 * then we are the one who should release the leader.
195 */
196 zap_leader = do_notify_parent(leader, leader->exit_signal);
197 if (zap_leader)
198 leader->exit_state = EXIT_DEAD;
199 }
200
201 write_unlock_irq(&tasklist_lock);
202 release_thread(p);
203 call_rcu(&p->rcu, delayed_put_task_struct);
204
205 p = leader;
206 if (unlikely(zap_leader))
207 goto repeat;
208}
209
210/*
211 * This checks not only the pgrp, but falls back on the pid if no
212 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
213 * without this...
214 *
215 * The caller must hold rcu lock or the tasklist lock.
216 */
217struct pid *session_of_pgrp(struct pid *pgrp)
218{
219 struct task_struct *p;
220 struct pid *sid = NULL;
221
222 p = pid_task(pgrp, PIDTYPE_PGID);
223 if (p == NULL)
224 p = pid_task(pgrp, PIDTYPE_PID);
225 if (p != NULL)
226 sid = task_session(p);
227
228 return sid;
229}
230
231/*
232 * Determine if a process group is "orphaned", according to the POSIX
233 * definition in 2.2.2.52. Orphaned process groups are not to be affected
234 * by terminal-generated stop signals. Newly orphaned process groups are
235 * to receive a SIGHUP and a SIGCONT.
236 *
237 * "I ask you, have you ever known what it is to be an orphan?"
238 */
239static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
240{
241 struct task_struct *p;
242
243 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
244 if ((p == ignored_task) ||
245 (p->exit_state && thread_group_empty(p)) ||
246 is_global_init(p->real_parent))
247 continue;
248
249 if (task_pgrp(p->real_parent) != pgrp &&
250 task_session(p->real_parent) == task_session(p))
251 return 0;
252 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
253
254 return 1;
255}
256
257int is_current_pgrp_orphaned(void)
258{
259 int retval;
260
261 read_lock(&tasklist_lock);
262 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
263 read_unlock(&tasklist_lock);
264
265 return retval;
266}
267
268static bool has_stopped_jobs(struct pid *pgrp)
269{
270 struct task_struct *p;
271
272 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
273 if (p->signal->flags & SIGNAL_STOP_STOPPED)
274 return true;
275 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
276
277 return false;
278}
279
280/*
281 * Check to see if any process groups have become orphaned as
282 * a result of our exiting, and if they have any stopped jobs,
283 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
284 */
285static void
286kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
287{
288 struct pid *pgrp = task_pgrp(tsk);
289 struct task_struct *ignored_task = tsk;
290
291 if (!parent)
292 /* exit: our father is in a different pgrp than
293 * we are and we were the only connection outside.
294 */
295 parent = tsk->real_parent;
296 else
297 /* reparent: our child is in a different pgrp than
298 * we are, and it was the only connection outside.
299 */
300 ignored_task = NULL;
301
302 if (task_pgrp(parent) != pgrp &&
303 task_session(parent) == task_session(tsk) &&
304 will_become_orphaned_pgrp(pgrp, ignored_task) &&
305 has_stopped_jobs(pgrp)) {
306 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
307 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
308 }
309}
310
311/**
312 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
313 *
314 * If a kernel thread is launched as a result of a system call, or if
315 * it ever exits, it should generally reparent itself to kthreadd so it
316 * isn't in the way of other processes and is correctly cleaned up on exit.
317 *
318 * The various task state such as scheduling policy and priority may have
319 * been inherited from a user process, so we reset them to sane values here.
320 *
321 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
322 */
323static void reparent_to_kthreadd(void)
324{
325 write_lock_irq(&tasklist_lock);
326
327 ptrace_unlink(current);
328 /* Reparent to init */
329 current->real_parent = current->parent = kthreadd_task;
330 list_move_tail(¤t->sibling, ¤t->real_parent->children);
331
332 /* Set the exit signal to SIGCHLD so we signal init on exit */
333 current->exit_signal = SIGCHLD;
334
335 if (task_nice(current) < 0)
336 set_user_nice(current, 0);
337 /* cpus_allowed? */
338 /* rt_priority? */
339 /* signals? */
340 memcpy(current->signal->rlim, init_task.signal->rlim,
341 sizeof(current->signal->rlim));
342
343 atomic_inc(&init_cred.usage);
344 commit_creds(&init_cred);
345 write_unlock_irq(&tasklist_lock);
346}
347
348void __set_special_pids(struct pid *pid)
349{
350 struct task_struct *curr = current->group_leader;
351
352 if (task_session(curr) != pid)
353 change_pid(curr, PIDTYPE_SID, pid);
354
355 if (task_pgrp(curr) != pid)
356 change_pid(curr, PIDTYPE_PGID, pid);
357}
358
359static void set_special_pids(struct pid *pid)
360{
361 write_lock_irq(&tasklist_lock);
362 __set_special_pids(pid);
363 write_unlock_irq(&tasklist_lock);
364}
365
366/*
367 * Let kernel threads use this to say that they allow a certain signal.
368 * Must not be used if kthread was cloned with CLONE_SIGHAND.
369 */
370int allow_signal(int sig)
371{
372 if (!valid_signal(sig) || sig < 1)
373 return -EINVAL;
374
375 spin_lock_irq(¤t->sighand->siglock);
376 /* This is only needed for daemonize()'ed kthreads */
377 sigdelset(¤t->blocked, sig);
378 /*
379 * Kernel threads handle their own signals. Let the signal code
380 * know it'll be handled, so that they don't get converted to
381 * SIGKILL or just silently dropped.
382 */
383 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
384 recalc_sigpending();
385 spin_unlock_irq(¤t->sighand->siglock);
386 return 0;
387}
388
389EXPORT_SYMBOL(allow_signal);
390
391int disallow_signal(int sig)
392{
393 if (!valid_signal(sig) || sig < 1)
394 return -EINVAL;
395
396 spin_lock_irq(¤t->sighand->siglock);
397 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
398 recalc_sigpending();
399 spin_unlock_irq(¤t->sighand->siglock);
400 return 0;
401}
402
403EXPORT_SYMBOL(disallow_signal);
404
405/*
406 * Put all the gunge required to become a kernel thread without
407 * attached user resources in one place where it belongs.
408 */
409
410void daemonize(const char *name, ...)
411{
412 va_list args;
413 sigset_t blocked;
414
415 va_start(args, name);
416 vsnprintf(current->comm, sizeof(current->comm), name, args);
417 va_end(args);
418
419 /*
420 * If we were started as result of loading a module, close all of the
421 * user space pages. We don't need them, and if we didn't close them
422 * they would be locked into memory.
423 */
424 exit_mm(current);
425 /*
426 * We don't want to have TIF_FREEZE set if the system-wide hibernation
427 * or suspend transition begins right now.
428 */
429 current->flags |= (PF_NOFREEZE | PF_KTHREAD);
430
431 if (current->nsproxy != &init_nsproxy) {
432 get_nsproxy(&init_nsproxy);
433 switch_task_namespaces(current, &init_nsproxy);
434 }
435 set_special_pids(&init_struct_pid);
436 proc_clear_tty(current);
437
438 /* Block and flush all signals */
439 sigfillset(&blocked);
440 sigprocmask(SIG_BLOCK, &blocked, NULL);
441 flush_signals(current);
442
443 /* Become as one with the init task */
444
445 daemonize_fs_struct();
446 exit_files(current);
447 current->files = init_task.files;
448 atomic_inc(¤t->files->count);
449
450 reparent_to_kthreadd();
451}
452
453EXPORT_SYMBOL(daemonize);
454
455static void close_files(struct files_struct * files)
456{
457 int i, j;
458 struct fdtable *fdt;
459
460 j = 0;
461
462 /*
463 * It is safe to dereference the fd table without RCU or
464 * ->file_lock because this is the last reference to the
465 * files structure. But use RCU to shut RCU-lockdep up.
466 */
467 rcu_read_lock();
468 fdt = files_fdtable(files);
469 rcu_read_unlock();
470 for (;;) {
471 unsigned long set;
472 i = j * __NFDBITS;
473 if (i >= fdt->max_fds)
474 break;
475 set = fdt->open_fds->fds_bits[j++];
476 while (set) {
477 if (set & 1) {
478 struct file * file = xchg(&fdt->fd[i], NULL);
479 if (file) {
480 filp_close(file, files);
481 cond_resched();
482 }
483 }
484 i++;
485 set >>= 1;
486 }
487 }
488}
489
490struct files_struct *get_files_struct(struct task_struct *task)
491{
492 struct files_struct *files;
493
494 task_lock(task);
495 files = task->files;
496 if (files)
497 atomic_inc(&files->count);
498 task_unlock(task);
499
500 return files;
501}
502
503void put_files_struct(struct files_struct *files)
504{
505 struct fdtable *fdt;
506
507 if (atomic_dec_and_test(&files->count)) {
508 close_files(files);
509 /*
510 * Free the fd and fdset arrays if we expanded them.
511 * If the fdtable was embedded, pass files for freeing
512 * at the end of the RCU grace period. Otherwise,
513 * you can free files immediately.
514 */
515 rcu_read_lock();
516 fdt = files_fdtable(files);
517 if (fdt != &files->fdtab)
518 kmem_cache_free(files_cachep, files);
519 free_fdtable(fdt);
520 rcu_read_unlock();
521 }
522}
523
524void reset_files_struct(struct files_struct *files)
525{
526 struct task_struct *tsk = current;
527 struct files_struct *old;
528
529 old = tsk->files;
530 task_lock(tsk);
531 tsk->files = files;
532 task_unlock(tsk);
533 put_files_struct(old);
534}
535
536void exit_files(struct task_struct *tsk)
537{
538 struct files_struct * files = tsk->files;
539
540 if (files) {
541 task_lock(tsk);
542 tsk->files = NULL;
543 task_unlock(tsk);
544 put_files_struct(files);
545 }
546}
547
548#ifdef CONFIG_MM_OWNER
549/*
550 * A task is exiting. If it owned this mm, find a new owner for the mm.
551 */
552void mm_update_next_owner(struct mm_struct *mm)
553{
554 struct task_struct *c, *g, *p = current;
555
556retry:
557 /*
558 * If the exiting or execing task is not the owner, it's
559 * someone else's problem.
560 */
561 if (mm->owner != p)
562 return;
563 /*
564 * The current owner is exiting/execing and there are no other
565 * candidates. Do not leave the mm pointing to a possibly
566 * freed task structure.
567 */
568 if (atomic_read(&mm->mm_users) <= 1) {
569 mm->owner = NULL;
570 return;
571 }
572
573 read_lock(&tasklist_lock);
574 /*
575 * Search in the children
576 */
577 list_for_each_entry(c, &p->children, sibling) {
578 if (c->mm == mm)
579 goto assign_new_owner;
580 }
581
582 /*
583 * Search in the siblings
584 */
585 list_for_each_entry(c, &p->real_parent->children, sibling) {
586 if (c->mm == mm)
587 goto assign_new_owner;
588 }
589
590 /*
591 * Search through everything else. We should not get
592 * here often
593 */
594 do_each_thread(g, c) {
595 if (c->mm == mm)
596 goto assign_new_owner;
597 } while_each_thread(g, c);
598
599 read_unlock(&tasklist_lock);
600 /*
601 * We found no owner yet mm_users > 1: this implies that we are
602 * most likely racing with swapoff (try_to_unuse()) or /proc or
603 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
604 */
605 mm->owner = NULL;
606 return;
607
608assign_new_owner:
609 BUG_ON(c == p);
610 get_task_struct(c);
611 /*
612 * The task_lock protects c->mm from changing.
613 * We always want mm->owner->mm == mm
614 */
615 task_lock(c);
616 /*
617 * Delay read_unlock() till we have the task_lock()
618 * to ensure that c does not slip away underneath us
619 */
620 read_unlock(&tasklist_lock);
621 if (c->mm != mm) {
622 task_unlock(c);
623 put_task_struct(c);
624 goto retry;
625 }
626 mm->owner = c;
627 task_unlock(c);
628 put_task_struct(c);
629}
630#endif /* CONFIG_MM_OWNER */
631
632/*
633 * Turn us into a lazy TLB process if we
634 * aren't already..
635 */
636static void exit_mm(struct task_struct * tsk)
637{
638 struct mm_struct *mm = tsk->mm;
639 struct core_state *core_state;
640
641 mm_release(tsk, mm);
642 if (!mm)
643 return;
644 /*
645 * Serialize with any possible pending coredump.
646 * We must hold mmap_sem around checking core_state
647 * and clearing tsk->mm. The core-inducing thread
648 * will increment ->nr_threads for each thread in the
649 * group with ->mm != NULL.
650 */
651 down_read(&mm->mmap_sem);
652 core_state = mm->core_state;
653 if (core_state) {
654 struct core_thread self;
655 up_read(&mm->mmap_sem);
656
657 self.task = tsk;
658 self.next = xchg(&core_state->dumper.next, &self);
659 /*
660 * Implies mb(), the result of xchg() must be visible
661 * to core_state->dumper.
662 */
663 if (atomic_dec_and_test(&core_state->nr_threads))
664 complete(&core_state->startup);
665
666 for (;;) {
667 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
668 if (!self.task) /* see coredump_finish() */
669 break;
670 schedule();
671 }
672 __set_task_state(tsk, TASK_RUNNING);
673 down_read(&mm->mmap_sem);
674 }
675 atomic_inc(&mm->mm_count);
676 BUG_ON(mm != tsk->active_mm);
677 /* more a memory barrier than a real lock */
678 task_lock(tsk);
679 tsk->mm = NULL;
680 up_read(&mm->mmap_sem);
681 enter_lazy_tlb(mm, current);
682 /* We don't want this task to be frozen prematurely */
683 clear_freeze_flag(tsk);
684 if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
685 atomic_dec(&mm->oom_disable_count);
686 task_unlock(tsk);
687 mm_update_next_owner(mm);
688 mmput(mm);
689}
690
691/*
692 * When we die, we re-parent all our children.
693 * Try to give them to another thread in our thread
694 * group, and if no such member exists, give it to
695 * the child reaper process (ie "init") in our pid
696 * space.
697 */
698static struct task_struct *find_new_reaper(struct task_struct *father)
699 __releases(&tasklist_lock)
700 __acquires(&tasklist_lock)
701{
702 struct pid_namespace *pid_ns = task_active_pid_ns(father);
703 struct task_struct *thread;
704
705 thread = father;
706 while_each_thread(father, thread) {
707 if (thread->flags & PF_EXITING)
708 continue;
709 if (unlikely(pid_ns->child_reaper == father))
710 pid_ns->child_reaper = thread;
711 return thread;
712 }
713
714 if (unlikely(pid_ns->child_reaper == father)) {
715 write_unlock_irq(&tasklist_lock);
716 if (unlikely(pid_ns == &init_pid_ns))
717 panic("Attempted to kill init!");
718
719 zap_pid_ns_processes(pid_ns);
720 write_lock_irq(&tasklist_lock);
721 /*
722 * We can not clear ->child_reaper or leave it alone.
723 * There may by stealth EXIT_DEAD tasks on ->children,
724 * forget_original_parent() must move them somewhere.
725 */
726 pid_ns->child_reaper = init_pid_ns.child_reaper;
727 }
728
729 return pid_ns->child_reaper;
730}
731
732/*
733* Any that need to be release_task'd are put on the @dead list.
734 */
735static void reparent_leader(struct task_struct *father, struct task_struct *p,
736 struct list_head *dead)
737{
738 list_move_tail(&p->sibling, &p->real_parent->children);
739
740 if (p->exit_state == EXIT_DEAD)
741 return;
742 /*
743 * If this is a threaded reparent there is no need to
744 * notify anyone anything has happened.
745 */
746 if (same_thread_group(p->real_parent, father))
747 return;
748
749 /* We don't want people slaying init. */
750 p->exit_signal = SIGCHLD;
751
752 /* If it has exited notify the new parent about this child's death. */
753 if (!p->ptrace &&
754 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
755 if (do_notify_parent(p, p->exit_signal)) {
756 p->exit_state = EXIT_DEAD;
757 list_move_tail(&p->sibling, dead);
758 }
759 }
760
761 kill_orphaned_pgrp(p, father);
762}
763
764static void forget_original_parent(struct task_struct *father)
765{
766 struct task_struct *p, *n, *reaper;
767 LIST_HEAD(dead_children);
768
769 write_lock_irq(&tasklist_lock);
770 /*
771 * Note that exit_ptrace() and find_new_reaper() might
772 * drop tasklist_lock and reacquire it.
773 */
774 exit_ptrace(father);
775 reaper = find_new_reaper(father);
776
777 list_for_each_entry_safe(p, n, &father->children, sibling) {
778 struct task_struct *t = p;
779 do {
780 t->real_parent = reaper;
781 if (t->parent == father) {
782 BUG_ON(t->ptrace);
783 t->parent = t->real_parent;
784 }
785 if (t->pdeath_signal)
786 group_send_sig_info(t->pdeath_signal,
787 SEND_SIG_NOINFO, t);
788 } while_each_thread(p, t);
789 reparent_leader(father, p, &dead_children);
790 }
791 write_unlock_irq(&tasklist_lock);
792
793 BUG_ON(!list_empty(&father->children));
794
795 list_for_each_entry_safe(p, n, &dead_children, sibling) {
796 list_del_init(&p->sibling);
797 release_task(p);
798 }
799}
800
801/*
802 * Send signals to all our closest relatives so that they know
803 * to properly mourn us..
804 */
805static void exit_notify(struct task_struct *tsk, int group_dead)
806{
807 bool autoreap;
808
809 /*
810 * This does two things:
811 *
812 * A. Make init inherit all the child processes
813 * B. Check to see if any process groups have become orphaned
814 * as a result of our exiting, and if they have any stopped
815 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
816 */
817 forget_original_parent(tsk);
818 exit_task_namespaces(tsk);
819
820 write_lock_irq(&tasklist_lock);
821 if (group_dead)
822 kill_orphaned_pgrp(tsk->group_leader, NULL);
823
824 /* Let father know we died
825 *
826 * Thread signals are configurable, but you aren't going to use
827 * that to send signals to arbitrary processes.
828 * That stops right now.
829 *
830 * If the parent exec id doesn't match the exec id we saved
831 * when we started then we know the parent has changed security
832 * domain.
833 *
834 * If our self_exec id doesn't match our parent_exec_id then
835 * we have changed execution domain as these two values started
836 * the same after a fork.
837 */
838 if (thread_group_leader(tsk) && tsk->exit_signal != SIGCHLD &&
839 (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
840 tsk->self_exec_id != tsk->parent_exec_id))
841 tsk->exit_signal = SIGCHLD;
842
843 if (unlikely(tsk->ptrace)) {
844 int sig = thread_group_leader(tsk) &&
845 thread_group_empty(tsk) &&
846 !ptrace_reparented(tsk) ?
847 tsk->exit_signal : SIGCHLD;
848 autoreap = do_notify_parent(tsk, sig);
849 } else if (thread_group_leader(tsk)) {
850 autoreap = thread_group_empty(tsk) &&
851 do_notify_parent(tsk, tsk->exit_signal);
852 } else {
853 autoreap = true;
854 }
855
856 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
857
858 /* mt-exec, de_thread() is waiting for group leader */
859 if (unlikely(tsk->signal->notify_count < 0))
860 wake_up_process(tsk->signal->group_exit_task);
861 write_unlock_irq(&tasklist_lock);
862
863 /* If the process is dead, release it - nobody will wait for it */
864 if (autoreap)
865 release_task(tsk);
866}
867
868#ifdef CONFIG_DEBUG_STACK_USAGE
869static void check_stack_usage(void)
870{
871 static DEFINE_SPINLOCK(low_water_lock);
872 static int lowest_to_date = THREAD_SIZE;
873 unsigned long free;
874
875 free = stack_not_used(current);
876
877 if (free >= lowest_to_date)
878 return;
879
880 spin_lock(&low_water_lock);
881 if (free < lowest_to_date) {
882 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
883 "left\n",
884 current->comm, free);
885 lowest_to_date = free;
886 }
887 spin_unlock(&low_water_lock);
888}
889#else
890static inline void check_stack_usage(void) {}
891#endif
892
893NORET_TYPE void do_exit(long code)
894{
895 struct task_struct *tsk = current;
896 int group_dead;
897
898 profile_task_exit(tsk);
899
900 WARN_ON(blk_needs_flush_plug(tsk));
901
902 if (unlikely(in_interrupt()))
903 panic("Aiee, killing interrupt handler!");
904 if (unlikely(!tsk->pid))
905 panic("Attempted to kill the idle task!");
906
907 /*
908 * If do_exit is called because this processes oopsed, it's possible
909 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
910 * continuing. Amongst other possible reasons, this is to prevent
911 * mm_release()->clear_child_tid() from writing to a user-controlled
912 * kernel address.
913 */
914 set_fs(USER_DS);
915
916 ptrace_event(PTRACE_EVENT_EXIT, code);
917
918 validate_creds_for_do_exit(tsk);
919
920 /*
921 * We're taking recursive faults here in do_exit. Safest is to just
922 * leave this task alone and wait for reboot.
923 */
924 if (unlikely(tsk->flags & PF_EXITING)) {
925 printk(KERN_ALERT
926 "Fixing recursive fault but reboot is needed!\n");
927 /*
928 * We can do this unlocked here. The futex code uses
929 * this flag just to verify whether the pi state
930 * cleanup has been done or not. In the worst case it
931 * loops once more. We pretend that the cleanup was
932 * done as there is no way to return. Either the
933 * OWNER_DIED bit is set by now or we push the blocked
934 * task into the wait for ever nirwana as well.
935 */
936 tsk->flags |= PF_EXITPIDONE;
937 set_current_state(TASK_UNINTERRUPTIBLE);
938 schedule();
939 }
940
941 exit_irq_thread();
942
943 exit_signals(tsk); /* sets PF_EXITING */
944 /*
945 * tsk->flags are checked in the futex code to protect against
946 * an exiting task cleaning up the robust pi futexes.
947 */
948 smp_mb();
949 raw_spin_unlock_wait(&tsk->pi_lock);
950
951 if (unlikely(in_atomic()))
952 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
953 current->comm, task_pid_nr(current),
954 preempt_count());
955
956 acct_update_integrals(tsk);
957 /* sync mm's RSS info before statistics gathering */
958 if (tsk->mm)
959 sync_mm_rss(tsk, tsk->mm);
960 group_dead = atomic_dec_and_test(&tsk->signal->live);
961 if (group_dead) {
962 hrtimer_cancel(&tsk->signal->real_timer);
963 exit_itimers(tsk->signal);
964 if (tsk->mm)
965 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
966 }
967 acct_collect(code, group_dead);
968 if (group_dead)
969 tty_audit_exit();
970 if (unlikely(tsk->audit_context))
971 audit_free(tsk);
972
973 tsk->exit_code = code;
974 taskstats_exit(tsk, group_dead);
975
976 exit_mm(tsk);
977
978 if (group_dead)
979 acct_process();
980 trace_sched_process_exit(tsk);
981
982 exit_sem(tsk);
983 exit_shm(tsk);
984 exit_files(tsk);
985 exit_fs(tsk);
986 check_stack_usage();
987 exit_thread();
988
989 /*
990 * Flush inherited counters to the parent - before the parent
991 * gets woken up by child-exit notifications.
992 *
993 * because of cgroup mode, must be called before cgroup_exit()
994 */
995 perf_event_exit_task(tsk);
996
997 cgroup_exit(tsk, 1);
998
999 if (group_dead)
1000 disassociate_ctty(1);
1001
1002 module_put(task_thread_info(tsk)->exec_domain->module);
1003
1004 proc_exit_connector(tsk);
1005
1006 /*
1007 * FIXME: do that only when needed, using sched_exit tracepoint
1008 */
1009 ptrace_put_breakpoints(tsk);
1010
1011 exit_notify(tsk, group_dead);
1012#ifdef CONFIG_NUMA
1013 task_lock(tsk);
1014 mpol_put(tsk->mempolicy);
1015 tsk->mempolicy = NULL;
1016 task_unlock(tsk);
1017#endif
1018#ifdef CONFIG_FUTEX
1019 if (unlikely(current->pi_state_cache))
1020 kfree(current->pi_state_cache);
1021#endif
1022 /*
1023 * Make sure we are holding no locks:
1024 */
1025 debug_check_no_locks_held(tsk);
1026 /*
1027 * We can do this unlocked here. The futex code uses this flag
1028 * just to verify whether the pi state cleanup has been done
1029 * or not. In the worst case it loops once more.
1030 */
1031 tsk->flags |= PF_EXITPIDONE;
1032
1033 if (tsk->io_context)
1034 exit_io_context(tsk);
1035
1036 if (tsk->splice_pipe)
1037 __free_pipe_info(tsk->splice_pipe);
1038
1039 validate_creds_for_do_exit(tsk);
1040
1041 preempt_disable();
1042 exit_rcu();
1043 /* causes final put_task_struct in finish_task_switch(). */
1044 tsk->state = TASK_DEAD;
1045 schedule();
1046 BUG();
1047 /* Avoid "noreturn function does return". */
1048 for (;;)
1049 cpu_relax(); /* For when BUG is null */
1050}
1051
1052EXPORT_SYMBOL_GPL(do_exit);
1053
1054NORET_TYPE void complete_and_exit(struct completion *comp, long code)
1055{
1056 if (comp)
1057 complete(comp);
1058
1059 do_exit(code);
1060}
1061
1062EXPORT_SYMBOL(complete_and_exit);
1063
1064SYSCALL_DEFINE1(exit, int, error_code)
1065{
1066 do_exit((error_code&0xff)<<8);
1067}
1068
1069/*
1070 * Take down every thread in the group. This is called by fatal signals
1071 * as well as by sys_exit_group (below).
1072 */
1073NORET_TYPE void
1074do_group_exit(int exit_code)
1075{
1076 struct signal_struct *sig = current->signal;
1077
1078 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1079
1080 if (signal_group_exit(sig))
1081 exit_code = sig->group_exit_code;
1082 else if (!thread_group_empty(current)) {
1083 struct sighand_struct *const sighand = current->sighand;
1084 spin_lock_irq(&sighand->siglock);
1085 if (signal_group_exit(sig))
1086 /* Another thread got here before we took the lock. */
1087 exit_code = sig->group_exit_code;
1088 else {
1089 sig->group_exit_code = exit_code;
1090 sig->flags = SIGNAL_GROUP_EXIT;
1091 zap_other_threads(current);
1092 }
1093 spin_unlock_irq(&sighand->siglock);
1094 }
1095
1096 do_exit(exit_code);
1097 /* NOTREACHED */
1098}
1099
1100/*
1101 * this kills every thread in the thread group. Note that any externally
1102 * wait4()-ing process will get the correct exit code - even if this
1103 * thread is not the thread group leader.
1104 */
1105SYSCALL_DEFINE1(exit_group, int, error_code)
1106{
1107 do_group_exit((error_code & 0xff) << 8);
1108 /* NOTREACHED */
1109 return 0;
1110}
1111
1112struct wait_opts {
1113 enum pid_type wo_type;
1114 int wo_flags;
1115 struct pid *wo_pid;
1116
1117 struct siginfo __user *wo_info;
1118 int __user *wo_stat;
1119 struct rusage __user *wo_rusage;
1120
1121 wait_queue_t child_wait;
1122 int notask_error;
1123};
1124
1125static inline
1126struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
1127{
1128 if (type != PIDTYPE_PID)
1129 task = task->group_leader;
1130 return task->pids[type].pid;
1131}
1132
1133static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
1134{
1135 return wo->wo_type == PIDTYPE_MAX ||
1136 task_pid_type(p, wo->wo_type) == wo->wo_pid;
1137}
1138
1139static int eligible_child(struct wait_opts *wo, struct task_struct *p)
1140{
1141 if (!eligible_pid(wo, p))
1142 return 0;
1143 /* Wait for all children (clone and not) if __WALL is set;
1144 * otherwise, wait for clone children *only* if __WCLONE is
1145 * set; otherwise, wait for non-clone children *only*. (Note:
1146 * A "clone" child here is one that reports to its parent
1147 * using a signal other than SIGCHLD.) */
1148 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
1149 && !(wo->wo_flags & __WALL))
1150 return 0;
1151
1152 return 1;
1153}
1154
1155static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
1156 pid_t pid, uid_t uid, int why, int status)
1157{
1158 struct siginfo __user *infop;
1159 int retval = wo->wo_rusage
1160 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1161
1162 put_task_struct(p);
1163 infop = wo->wo_info;
1164 if (infop) {
1165 if (!retval)
1166 retval = put_user(SIGCHLD, &infop->si_signo);
1167 if (!retval)
1168 retval = put_user(0, &infop->si_errno);
1169 if (!retval)
1170 retval = put_user((short)why, &infop->si_code);
1171 if (!retval)
1172 retval = put_user(pid, &infop->si_pid);
1173 if (!retval)
1174 retval = put_user(uid, &infop->si_uid);
1175 if (!retval)
1176 retval = put_user(status, &infop->si_status);
1177 }
1178 if (!retval)
1179 retval = pid;
1180 return retval;
1181}
1182
1183/*
1184 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1185 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1186 * the lock and this task is uninteresting. If we return nonzero, we have
1187 * released the lock and the system call should return.
1188 */
1189static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1190{
1191 unsigned long state;
1192 int retval, status, traced;
1193 pid_t pid = task_pid_vnr(p);
1194 uid_t uid = __task_cred(p)->uid;
1195 struct siginfo __user *infop;
1196
1197 if (!likely(wo->wo_flags & WEXITED))
1198 return 0;
1199
1200 if (unlikely(wo->wo_flags & WNOWAIT)) {
1201 int exit_code = p->exit_code;
1202 int why;
1203
1204 get_task_struct(p);
1205 read_unlock(&tasklist_lock);
1206 if ((exit_code & 0x7f) == 0) {
1207 why = CLD_EXITED;
1208 status = exit_code >> 8;
1209 } else {
1210 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1211 status = exit_code & 0x7f;
1212 }
1213 return wait_noreap_copyout(wo, p, pid, uid, why, status);
1214 }
1215
1216 /*
1217 * Try to move the task's state to DEAD
1218 * only one thread is allowed to do this:
1219 */
1220 state = xchg(&p->exit_state, EXIT_DEAD);
1221 if (state != EXIT_ZOMBIE) {
1222 BUG_ON(state != EXIT_DEAD);
1223 return 0;
1224 }
1225
1226 traced = ptrace_reparented(p);
1227 /*
1228 * It can be ptraced but not reparented, check
1229 * thread_group_leader() to filter out sub-threads.
1230 */
1231 if (likely(!traced) && thread_group_leader(p)) {
1232 struct signal_struct *psig;
1233 struct signal_struct *sig;
1234 unsigned long maxrss;
1235 cputime_t tgutime, tgstime;
1236
1237 /*
1238 * The resource counters for the group leader are in its
1239 * own task_struct. Those for dead threads in the group
1240 * are in its signal_struct, as are those for the child
1241 * processes it has previously reaped. All these
1242 * accumulate in the parent's signal_struct c* fields.
1243 *
1244 * We don't bother to take a lock here to protect these
1245 * p->signal fields, because they are only touched by
1246 * __exit_signal, which runs with tasklist_lock
1247 * write-locked anyway, and so is excluded here. We do
1248 * need to protect the access to parent->signal fields,
1249 * as other threads in the parent group can be right
1250 * here reaping other children at the same time.
1251 *
1252 * We use thread_group_times() to get times for the thread
1253 * group, which consolidates times for all threads in the
1254 * group including the group leader.
1255 */
1256 thread_group_times(p, &tgutime, &tgstime);
1257 spin_lock_irq(&p->real_parent->sighand->siglock);
1258 psig = p->real_parent->signal;
1259 sig = p->signal;
1260 psig->cutime =
1261 cputime_add(psig->cutime,
1262 cputime_add(tgutime,
1263 sig->cutime));
1264 psig->cstime =
1265 cputime_add(psig->cstime,
1266 cputime_add(tgstime,
1267 sig->cstime));
1268 psig->cgtime =
1269 cputime_add(psig->cgtime,
1270 cputime_add(p->gtime,
1271 cputime_add(sig->gtime,
1272 sig->cgtime)));
1273 psig->cmin_flt +=
1274 p->min_flt + sig->min_flt + sig->cmin_flt;
1275 psig->cmaj_flt +=
1276 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1277 psig->cnvcsw +=
1278 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1279 psig->cnivcsw +=
1280 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1281 psig->cinblock +=
1282 task_io_get_inblock(p) +
1283 sig->inblock + sig->cinblock;
1284 psig->coublock +=
1285 task_io_get_oublock(p) +
1286 sig->oublock + sig->coublock;
1287 maxrss = max(sig->maxrss, sig->cmaxrss);
1288 if (psig->cmaxrss < maxrss)
1289 psig->cmaxrss = maxrss;
1290 task_io_accounting_add(&psig->ioac, &p->ioac);
1291 task_io_accounting_add(&psig->ioac, &sig->ioac);
1292 spin_unlock_irq(&p->real_parent->sighand->siglock);
1293 }
1294
1295 /*
1296 * Now we are sure this task is interesting, and no other
1297 * thread can reap it because we set its state to EXIT_DEAD.
1298 */
1299 read_unlock(&tasklist_lock);
1300
1301 retval = wo->wo_rusage
1302 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1303 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1304 ? p->signal->group_exit_code : p->exit_code;
1305 if (!retval && wo->wo_stat)
1306 retval = put_user(status, wo->wo_stat);
1307
1308 infop = wo->wo_info;
1309 if (!retval && infop)
1310 retval = put_user(SIGCHLD, &infop->si_signo);
1311 if (!retval && infop)
1312 retval = put_user(0, &infop->si_errno);
1313 if (!retval && infop) {
1314 int why;
1315
1316 if ((status & 0x7f) == 0) {
1317 why = CLD_EXITED;
1318 status >>= 8;
1319 } else {
1320 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1321 status &= 0x7f;
1322 }
1323 retval = put_user((short)why, &infop->si_code);
1324 if (!retval)
1325 retval = put_user(status, &infop->si_status);
1326 }
1327 if (!retval && infop)
1328 retval = put_user(pid, &infop->si_pid);
1329 if (!retval && infop)
1330 retval = put_user(uid, &infop->si_uid);
1331 if (!retval)
1332 retval = pid;
1333
1334 if (traced) {
1335 write_lock_irq(&tasklist_lock);
1336 /* We dropped tasklist, ptracer could die and untrace */
1337 ptrace_unlink(p);
1338 /*
1339 * If this is not a sub-thread, notify the parent.
1340 * If parent wants a zombie, don't release it now.
1341 */
1342 if (thread_group_leader(p) &&
1343 !do_notify_parent(p, p->exit_signal)) {
1344 p->exit_state = EXIT_ZOMBIE;
1345 p = NULL;
1346 }
1347 write_unlock_irq(&tasklist_lock);
1348 }
1349 if (p != NULL)
1350 release_task(p);
1351
1352 return retval;
1353}
1354
1355static int *task_stopped_code(struct task_struct *p, bool ptrace)
1356{
1357 if (ptrace) {
1358 if (task_is_stopped_or_traced(p) &&
1359 !(p->jobctl & JOBCTL_LISTENING))
1360 return &p->exit_code;
1361 } else {
1362 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1363 return &p->signal->group_exit_code;
1364 }
1365 return NULL;
1366}
1367
1368/**
1369 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1370 * @wo: wait options
1371 * @ptrace: is the wait for ptrace
1372 * @p: task to wait for
1373 *
1374 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1375 *
1376 * CONTEXT:
1377 * read_lock(&tasklist_lock), which is released if return value is
1378 * non-zero. Also, grabs and releases @p->sighand->siglock.
1379 *
1380 * RETURNS:
1381 * 0 if wait condition didn't exist and search for other wait conditions
1382 * should continue. Non-zero return, -errno on failure and @p's pid on
1383 * success, implies that tasklist_lock is released and wait condition
1384 * search should terminate.
1385 */
1386static int wait_task_stopped(struct wait_opts *wo,
1387 int ptrace, struct task_struct *p)
1388{
1389 struct siginfo __user *infop;
1390 int retval, exit_code, *p_code, why;
1391 uid_t uid = 0; /* unneeded, required by compiler */
1392 pid_t pid;
1393
1394 /*
1395 * Traditionally we see ptrace'd stopped tasks regardless of options.
1396 */
1397 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1398 return 0;
1399
1400 if (!task_stopped_code(p, ptrace))
1401 return 0;
1402
1403 exit_code = 0;
1404 spin_lock_irq(&p->sighand->siglock);
1405
1406 p_code = task_stopped_code(p, ptrace);
1407 if (unlikely(!p_code))
1408 goto unlock_sig;
1409
1410 exit_code = *p_code;
1411 if (!exit_code)
1412 goto unlock_sig;
1413
1414 if (!unlikely(wo->wo_flags & WNOWAIT))
1415 *p_code = 0;
1416
1417 uid = task_uid(p);
1418unlock_sig:
1419 spin_unlock_irq(&p->sighand->siglock);
1420 if (!exit_code)
1421 return 0;
1422
1423 /*
1424 * Now we are pretty sure this task is interesting.
1425 * Make sure it doesn't get reaped out from under us while we
1426 * give up the lock and then examine it below. We don't want to
1427 * keep holding onto the tasklist_lock while we call getrusage and
1428 * possibly take page faults for user memory.
1429 */
1430 get_task_struct(p);
1431 pid = task_pid_vnr(p);
1432 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1433 read_unlock(&tasklist_lock);
1434
1435 if (unlikely(wo->wo_flags & WNOWAIT))
1436 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
1437
1438 retval = wo->wo_rusage
1439 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1440 if (!retval && wo->wo_stat)
1441 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
1442
1443 infop = wo->wo_info;
1444 if (!retval && infop)
1445 retval = put_user(SIGCHLD, &infop->si_signo);
1446 if (!retval && infop)
1447 retval = put_user(0, &infop->si_errno);
1448 if (!retval && infop)
1449 retval = put_user((short)why, &infop->si_code);
1450 if (!retval && infop)
1451 retval = put_user(exit_code, &infop->si_status);
1452 if (!retval && infop)
1453 retval = put_user(pid, &infop->si_pid);
1454 if (!retval && infop)
1455 retval = put_user(uid, &infop->si_uid);
1456 if (!retval)
1457 retval = pid;
1458 put_task_struct(p);
1459
1460 BUG_ON(!retval);
1461 return retval;
1462}
1463
1464/*
1465 * Handle do_wait work for one task in a live, non-stopped state.
1466 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1467 * the lock and this task is uninteresting. If we return nonzero, we have
1468 * released the lock and the system call should return.
1469 */
1470static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1471{
1472 int retval;
1473 pid_t pid;
1474 uid_t uid;
1475
1476 if (!unlikely(wo->wo_flags & WCONTINUED))
1477 return 0;
1478
1479 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1480 return 0;
1481
1482 spin_lock_irq(&p->sighand->siglock);
1483 /* Re-check with the lock held. */
1484 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1485 spin_unlock_irq(&p->sighand->siglock);
1486 return 0;
1487 }
1488 if (!unlikely(wo->wo_flags & WNOWAIT))
1489 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1490 uid = task_uid(p);
1491 spin_unlock_irq(&p->sighand->siglock);
1492
1493 pid = task_pid_vnr(p);
1494 get_task_struct(p);
1495 read_unlock(&tasklist_lock);
1496
1497 if (!wo->wo_info) {
1498 retval = wo->wo_rusage
1499 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1500 put_task_struct(p);
1501 if (!retval && wo->wo_stat)
1502 retval = put_user(0xffff, wo->wo_stat);
1503 if (!retval)
1504 retval = pid;
1505 } else {
1506 retval = wait_noreap_copyout(wo, p, pid, uid,
1507 CLD_CONTINUED, SIGCONT);
1508 BUG_ON(retval == 0);
1509 }
1510
1511 return retval;
1512}
1513
1514/*
1515 * Consider @p for a wait by @parent.
1516 *
1517 * -ECHILD should be in ->notask_error before the first call.
1518 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1519 * Returns zero if the search for a child should continue;
1520 * then ->notask_error is 0 if @p is an eligible child,
1521 * or another error from security_task_wait(), or still -ECHILD.
1522 */
1523static int wait_consider_task(struct wait_opts *wo, int ptrace,
1524 struct task_struct *p)
1525{
1526 int ret = eligible_child(wo, p);
1527 if (!ret)
1528 return ret;
1529
1530 ret = security_task_wait(p);
1531 if (unlikely(ret < 0)) {
1532 /*
1533 * If we have not yet seen any eligible child,
1534 * then let this error code replace -ECHILD.
1535 * A permission error will give the user a clue
1536 * to look for security policy problems, rather
1537 * than for mysterious wait bugs.
1538 */
1539 if (wo->notask_error)
1540 wo->notask_error = ret;
1541 return 0;
1542 }
1543
1544 /* dead body doesn't have much to contribute */
1545 if (p->exit_state == EXIT_DEAD)
1546 return 0;
1547
1548 /* slay zombie? */
1549 if (p->exit_state == EXIT_ZOMBIE) {
1550 /*
1551 * A zombie ptracee is only visible to its ptracer.
1552 * Notification and reaping will be cascaded to the real
1553 * parent when the ptracer detaches.
1554 */
1555 if (likely(!ptrace) && unlikely(p->ptrace)) {
1556 /* it will become visible, clear notask_error */
1557 wo->notask_error = 0;
1558 return 0;
1559 }
1560
1561 /* we don't reap group leaders with subthreads */
1562 if (!delay_group_leader(p))
1563 return wait_task_zombie(wo, p);
1564
1565 /*
1566 * Allow access to stopped/continued state via zombie by
1567 * falling through. Clearing of notask_error is complex.
1568 *
1569 * When !@ptrace:
1570 *
1571 * If WEXITED is set, notask_error should naturally be
1572 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1573 * so, if there are live subthreads, there are events to
1574 * wait for. If all subthreads are dead, it's still safe
1575 * to clear - this function will be called again in finite
1576 * amount time once all the subthreads are released and
1577 * will then return without clearing.
1578 *
1579 * When @ptrace:
1580 *
1581 * Stopped state is per-task and thus can't change once the
1582 * target task dies. Only continued and exited can happen.
1583 * Clear notask_error if WCONTINUED | WEXITED.
1584 */
1585 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1586 wo->notask_error = 0;
1587 } else {
1588 /*
1589 * If @p is ptraced by a task in its real parent's group,
1590 * hide group stop/continued state when looking at @p as
1591 * the real parent; otherwise, a single stop can be
1592 * reported twice as group and ptrace stops.
1593 *
1594 * If a ptracer wants to distinguish the two events for its
1595 * own children, it should create a separate process which
1596 * takes the role of real parent.
1597 */
1598 if (likely(!ptrace) && p->ptrace && !ptrace_reparented(p))
1599 return 0;
1600
1601 /*
1602 * @p is alive and it's gonna stop, continue or exit, so
1603 * there always is something to wait for.
1604 */
1605 wo->notask_error = 0;
1606 }
1607
1608 /*
1609 * Wait for stopped. Depending on @ptrace, different stopped state
1610 * is used and the two don't interact with each other.
1611 */
1612 ret = wait_task_stopped(wo, ptrace, p);
1613 if (ret)
1614 return ret;
1615
1616 /*
1617 * Wait for continued. There's only one continued state and the
1618 * ptracer can consume it which can confuse the real parent. Don't
1619 * use WCONTINUED from ptracer. You don't need or want it.
1620 */
1621 return wait_task_continued(wo, p);
1622}
1623
1624/*
1625 * Do the work of do_wait() for one thread in the group, @tsk.
1626 *
1627 * -ECHILD should be in ->notask_error before the first call.
1628 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1629 * Returns zero if the search for a child should continue; then
1630 * ->notask_error is 0 if there were any eligible children,
1631 * or another error from security_task_wait(), or still -ECHILD.
1632 */
1633static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1634{
1635 struct task_struct *p;
1636
1637 list_for_each_entry(p, &tsk->children, sibling) {
1638 int ret = wait_consider_task(wo, 0, p);
1639 if (ret)
1640 return ret;
1641 }
1642
1643 return 0;
1644}
1645
1646static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1647{
1648 struct task_struct *p;
1649
1650 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1651 int ret = wait_consider_task(wo, 1, p);
1652 if (ret)
1653 return ret;
1654 }
1655
1656 return 0;
1657}
1658
1659static int child_wait_callback(wait_queue_t *wait, unsigned mode,
1660 int sync, void *key)
1661{
1662 struct wait_opts *wo = container_of(wait, struct wait_opts,
1663 child_wait);
1664 struct task_struct *p = key;
1665
1666 if (!eligible_pid(wo, p))
1667 return 0;
1668
1669 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1670 return 0;
1671
1672 return default_wake_function(wait, mode, sync, key);
1673}
1674
1675void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1676{
1677 __wake_up_sync_key(&parent->signal->wait_chldexit,
1678 TASK_INTERRUPTIBLE, 1, p);
1679}
1680
1681static long do_wait(struct wait_opts *wo)
1682{
1683 struct task_struct *tsk;
1684 int retval;
1685
1686 trace_sched_process_wait(wo->wo_pid);
1687
1688 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1689 wo->child_wait.private = current;
1690 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1691repeat:
1692 /*
1693 * If there is nothing that can match our critiera just get out.
1694 * We will clear ->notask_error to zero if we see any child that
1695 * might later match our criteria, even if we are not able to reap
1696 * it yet.
1697 */
1698 wo->notask_error = -ECHILD;
1699 if ((wo->wo_type < PIDTYPE_MAX) &&
1700 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1701 goto notask;
1702
1703 set_current_state(TASK_INTERRUPTIBLE);
1704 read_lock(&tasklist_lock);
1705 tsk = current;
1706 do {
1707 retval = do_wait_thread(wo, tsk);
1708 if (retval)
1709 goto end;
1710
1711 retval = ptrace_do_wait(wo, tsk);
1712 if (retval)
1713 goto end;
1714
1715 if (wo->wo_flags & __WNOTHREAD)
1716 break;
1717 } while_each_thread(current, tsk);
1718 read_unlock(&tasklist_lock);
1719
1720notask:
1721 retval = wo->notask_error;
1722 if (!retval && !(wo->wo_flags & WNOHANG)) {
1723 retval = -ERESTARTSYS;
1724 if (!signal_pending(current)) {
1725 schedule();
1726 goto repeat;
1727 }
1728 }
1729end:
1730 __set_current_state(TASK_RUNNING);
1731 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1732 return retval;
1733}
1734
1735SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1736 infop, int, options, struct rusage __user *, ru)
1737{
1738 struct wait_opts wo;
1739 struct pid *pid = NULL;
1740 enum pid_type type;
1741 long ret;
1742
1743 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1744 return -EINVAL;
1745 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1746 return -EINVAL;
1747
1748 switch (which) {
1749 case P_ALL:
1750 type = PIDTYPE_MAX;
1751 break;
1752 case P_PID:
1753 type = PIDTYPE_PID;
1754 if (upid <= 0)
1755 return -EINVAL;
1756 break;
1757 case P_PGID:
1758 type = PIDTYPE_PGID;
1759 if (upid <= 0)
1760 return -EINVAL;
1761 break;
1762 default:
1763 return -EINVAL;
1764 }
1765
1766 if (type < PIDTYPE_MAX)
1767 pid = find_get_pid(upid);
1768
1769 wo.wo_type = type;
1770 wo.wo_pid = pid;
1771 wo.wo_flags = options;
1772 wo.wo_info = infop;
1773 wo.wo_stat = NULL;
1774 wo.wo_rusage = ru;
1775 ret = do_wait(&wo);
1776
1777 if (ret > 0) {
1778 ret = 0;
1779 } else if (infop) {
1780 /*
1781 * For a WNOHANG return, clear out all the fields
1782 * we would set so the user can easily tell the
1783 * difference.
1784 */
1785 if (!ret)
1786 ret = put_user(0, &infop->si_signo);
1787 if (!ret)
1788 ret = put_user(0, &infop->si_errno);
1789 if (!ret)
1790 ret = put_user(0, &infop->si_code);
1791 if (!ret)
1792 ret = put_user(0, &infop->si_pid);
1793 if (!ret)
1794 ret = put_user(0, &infop->si_uid);
1795 if (!ret)
1796 ret = put_user(0, &infop->si_status);
1797 }
1798
1799 put_pid(pid);
1800
1801 /* avoid REGPARM breakage on x86: */
1802 asmlinkage_protect(5, ret, which, upid, infop, options, ru);
1803 return ret;
1804}
1805
1806SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1807 int, options, struct rusage __user *, ru)
1808{
1809 struct wait_opts wo;
1810 struct pid *pid = NULL;
1811 enum pid_type type;
1812 long ret;
1813
1814 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1815 __WNOTHREAD|__WCLONE|__WALL))
1816 return -EINVAL;
1817
1818 if (upid == -1)
1819 type = PIDTYPE_MAX;
1820 else if (upid < 0) {
1821 type = PIDTYPE_PGID;
1822 pid = find_get_pid(-upid);
1823 } else if (upid == 0) {
1824 type = PIDTYPE_PGID;
1825 pid = get_task_pid(current, PIDTYPE_PGID);
1826 } else /* upid > 0 */ {
1827 type = PIDTYPE_PID;
1828 pid = find_get_pid(upid);
1829 }
1830
1831 wo.wo_type = type;
1832 wo.wo_pid = pid;
1833 wo.wo_flags = options | WEXITED;
1834 wo.wo_info = NULL;
1835 wo.wo_stat = stat_addr;
1836 wo.wo_rusage = ru;
1837 ret = do_wait(&wo);
1838 put_pid(pid);
1839
1840 /* avoid REGPARM breakage on x86: */
1841 asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
1842 return ret;
1843}
1844
1845#ifdef __ARCH_WANT_SYS_WAITPID
1846
1847/*
1848 * sys_waitpid() remains for compatibility. waitpid() should be
1849 * implemented by calling sys_wait4() from libc.a.
1850 */
1851SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1852{
1853 return sys_wait4(pid, stat_addr, options, NULL);
1854}
1855
1856#endif