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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/kernel/exit.c
4 *
5 * Copyright (C) 1991, 1992 Linus Torvalds
6 */
7
8#include <linux/mm.h>
9#include <linux/slab.h>
10#include <linux/sched/autogroup.h>
11#include <linux/sched/mm.h>
12#include <linux/sched/stat.h>
13#include <linux/sched/task.h>
14#include <linux/sched/task_stack.h>
15#include <linux/sched/cputime.h>
16#include <linux/interrupt.h>
17#include <linux/module.h>
18#include <linux/capability.h>
19#include <linux/completion.h>
20#include <linux/personality.h>
21#include <linux/tty.h>
22#include <linux/iocontext.h>
23#include <linux/key.h>
24#include <linux/cpu.h>
25#include <linux/acct.h>
26#include <linux/tsacct_kern.h>
27#include <linux/file.h>
28#include <linux/fdtable.h>
29#include <linux/freezer.h>
30#include <linux/binfmts.h>
31#include <linux/nsproxy.h>
32#include <linux/pid_namespace.h>
33#include <linux/ptrace.h>
34#include <linux/profile.h>
35#include <linux/mount.h>
36#include <linux/proc_fs.h>
37#include <linux/kthread.h>
38#include <linux/mempolicy.h>
39#include <linux/taskstats_kern.h>
40#include <linux/delayacct.h>
41#include <linux/cgroup.h>
42#include <linux/syscalls.h>
43#include <linux/signal.h>
44#include <linux/posix-timers.h>
45#include <linux/cn_proc.h>
46#include <linux/mutex.h>
47#include <linux/futex.h>
48#include <linux/pipe_fs_i.h>
49#include <linux/audit.h> /* for audit_free() */
50#include <linux/resource.h>
51#include <linux/task_io_accounting_ops.h>
52#include <linux/blkdev.h>
53#include <linux/task_work.h>
54#include <linux/fs_struct.h>
55#include <linux/init_task.h>
56#include <linux/perf_event.h>
57#include <trace/events/sched.h>
58#include <linux/hw_breakpoint.h>
59#include <linux/oom.h>
60#include <linux/writeback.h>
61#include <linux/shm.h>
62#include <linux/kcov.h>
63#include <linux/kmsan.h>
64#include <linux/random.h>
65#include <linux/rcuwait.h>
66#include <linux/compat.h>
67#include <linux/io_uring.h>
68#include <linux/kprobes.h>
69#include <linux/rethook.h>
70#include <linux/sysfs.h>
71
72#include <linux/uaccess.h>
73#include <asm/unistd.h>
74#include <asm/mmu_context.h>
75
76/*
77 * The default value should be high enough to not crash a system that randomly
78 * crashes its kernel from time to time, but low enough to at least not permit
79 * overflowing 32-bit refcounts or the ldsem writer count.
80 */
81static unsigned int oops_limit = 10000;
82
83#ifdef CONFIG_SYSCTL
84static struct ctl_table kern_exit_table[] = {
85 {
86 .procname = "oops_limit",
87 .data = &oops_limit,
88 .maxlen = sizeof(oops_limit),
89 .mode = 0644,
90 .proc_handler = proc_douintvec,
91 },
92 { }
93};
94
95static __init int kernel_exit_sysctls_init(void)
96{
97 register_sysctl_init("kernel", kern_exit_table);
98 return 0;
99}
100late_initcall(kernel_exit_sysctls_init);
101#endif
102
103static atomic_t oops_count = ATOMIC_INIT(0);
104
105#ifdef CONFIG_SYSFS
106static ssize_t oops_count_show(struct kobject *kobj, struct kobj_attribute *attr,
107 char *page)
108{
109 return sysfs_emit(page, "%d\n", atomic_read(&oops_count));
110}
111
112static struct kobj_attribute oops_count_attr = __ATTR_RO(oops_count);
113
114static __init int kernel_exit_sysfs_init(void)
115{
116 sysfs_add_file_to_group(kernel_kobj, &oops_count_attr.attr, NULL);
117 return 0;
118}
119late_initcall(kernel_exit_sysfs_init);
120#endif
121
122static void __unhash_process(struct task_struct *p, bool group_dead)
123{
124 nr_threads--;
125 detach_pid(p, PIDTYPE_PID);
126 if (group_dead) {
127 detach_pid(p, PIDTYPE_TGID);
128 detach_pid(p, PIDTYPE_PGID);
129 detach_pid(p, PIDTYPE_SID);
130
131 list_del_rcu(&p->tasks);
132 list_del_init(&p->sibling);
133 __this_cpu_dec(process_counts);
134 }
135 list_del_rcu(&p->thread_group);
136 list_del_rcu(&p->thread_node);
137}
138
139/*
140 * This function expects the tasklist_lock write-locked.
141 */
142static void __exit_signal(struct task_struct *tsk)
143{
144 struct signal_struct *sig = tsk->signal;
145 bool group_dead = thread_group_leader(tsk);
146 struct sighand_struct *sighand;
147 struct tty_struct *tty;
148 u64 utime, stime;
149
150 sighand = rcu_dereference_check(tsk->sighand,
151 lockdep_tasklist_lock_is_held());
152 spin_lock(&sighand->siglock);
153
154#ifdef CONFIG_POSIX_TIMERS
155 posix_cpu_timers_exit(tsk);
156 if (group_dead)
157 posix_cpu_timers_exit_group(tsk);
158#endif
159
160 if (group_dead) {
161 tty = sig->tty;
162 sig->tty = NULL;
163 } else {
164 /*
165 * If there is any task waiting for the group exit
166 * then notify it:
167 */
168 if (sig->notify_count > 0 && !--sig->notify_count)
169 wake_up_process(sig->group_exec_task);
170
171 if (tsk == sig->curr_target)
172 sig->curr_target = next_thread(tsk);
173 }
174
175 add_device_randomness((const void*) &tsk->se.sum_exec_runtime,
176 sizeof(unsigned long long));
177
178 /*
179 * Accumulate here the counters for all threads as they die. We could
180 * skip the group leader because it is the last user of signal_struct,
181 * but we want to avoid the race with thread_group_cputime() which can
182 * see the empty ->thread_head list.
183 */
184 task_cputime(tsk, &utime, &stime);
185 write_seqlock(&sig->stats_lock);
186 sig->utime += utime;
187 sig->stime += stime;
188 sig->gtime += task_gtime(tsk);
189 sig->min_flt += tsk->min_flt;
190 sig->maj_flt += tsk->maj_flt;
191 sig->nvcsw += tsk->nvcsw;
192 sig->nivcsw += tsk->nivcsw;
193 sig->inblock += task_io_get_inblock(tsk);
194 sig->oublock += task_io_get_oublock(tsk);
195 task_io_accounting_add(&sig->ioac, &tsk->ioac);
196 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
197 sig->nr_threads--;
198 __unhash_process(tsk, group_dead);
199 write_sequnlock(&sig->stats_lock);
200
201 /*
202 * Do this under ->siglock, we can race with another thread
203 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
204 */
205 flush_sigqueue(&tsk->pending);
206 tsk->sighand = NULL;
207 spin_unlock(&sighand->siglock);
208
209 __cleanup_sighand(sighand);
210 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
211 if (group_dead) {
212 flush_sigqueue(&sig->shared_pending);
213 tty_kref_put(tty);
214 }
215}
216
217static void delayed_put_task_struct(struct rcu_head *rhp)
218{
219 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
220
221 kprobe_flush_task(tsk);
222 rethook_flush_task(tsk);
223 perf_event_delayed_put(tsk);
224 trace_sched_process_free(tsk);
225 put_task_struct(tsk);
226}
227
228void put_task_struct_rcu_user(struct task_struct *task)
229{
230 if (refcount_dec_and_test(&task->rcu_users))
231 call_rcu(&task->rcu, delayed_put_task_struct);
232}
233
234void __weak release_thread(struct task_struct *dead_task)
235{
236}
237
238void release_task(struct task_struct *p)
239{
240 struct task_struct *leader;
241 struct pid *thread_pid;
242 int zap_leader;
243repeat:
244 /* don't need to get the RCU readlock here - the process is dead and
245 * can't be modifying its own credentials. But shut RCU-lockdep up */
246 rcu_read_lock();
247 dec_rlimit_ucounts(task_ucounts(p), UCOUNT_RLIMIT_NPROC, 1);
248 rcu_read_unlock();
249
250 cgroup_release(p);
251
252 write_lock_irq(&tasklist_lock);
253 ptrace_release_task(p);
254 thread_pid = get_pid(p->thread_pid);
255 __exit_signal(p);
256
257 /*
258 * If we are the last non-leader member of the thread
259 * group, and the leader is zombie, then notify the
260 * group leader's parent process. (if it wants notification.)
261 */
262 zap_leader = 0;
263 leader = p->group_leader;
264 if (leader != p && thread_group_empty(leader)
265 && leader->exit_state == EXIT_ZOMBIE) {
266 /*
267 * If we were the last child thread and the leader has
268 * exited already, and the leader's parent ignores SIGCHLD,
269 * then we are the one who should release the leader.
270 */
271 zap_leader = do_notify_parent(leader, leader->exit_signal);
272 if (zap_leader)
273 leader->exit_state = EXIT_DEAD;
274 }
275
276 write_unlock_irq(&tasklist_lock);
277 seccomp_filter_release(p);
278 proc_flush_pid(thread_pid);
279 put_pid(thread_pid);
280 release_thread(p);
281 put_task_struct_rcu_user(p);
282
283 p = leader;
284 if (unlikely(zap_leader))
285 goto repeat;
286}
287
288int rcuwait_wake_up(struct rcuwait *w)
289{
290 int ret = 0;
291 struct task_struct *task;
292
293 rcu_read_lock();
294
295 /*
296 * Order condition vs @task, such that everything prior to the load
297 * of @task is visible. This is the condition as to why the user called
298 * rcuwait_wake() in the first place. Pairs with set_current_state()
299 * barrier (A) in rcuwait_wait_event().
300 *
301 * WAIT WAKE
302 * [S] tsk = current [S] cond = true
303 * MB (A) MB (B)
304 * [L] cond [L] tsk
305 */
306 smp_mb(); /* (B) */
307
308 task = rcu_dereference(w->task);
309 if (task)
310 ret = wake_up_process(task);
311 rcu_read_unlock();
312
313 return ret;
314}
315EXPORT_SYMBOL_GPL(rcuwait_wake_up);
316
317/*
318 * Determine if a process group is "orphaned", according to the POSIX
319 * definition in 2.2.2.52. Orphaned process groups are not to be affected
320 * by terminal-generated stop signals. Newly orphaned process groups are
321 * to receive a SIGHUP and a SIGCONT.
322 *
323 * "I ask you, have you ever known what it is to be an orphan?"
324 */
325static int will_become_orphaned_pgrp(struct pid *pgrp,
326 struct task_struct *ignored_task)
327{
328 struct task_struct *p;
329
330 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
331 if ((p == ignored_task) ||
332 (p->exit_state && thread_group_empty(p)) ||
333 is_global_init(p->real_parent))
334 continue;
335
336 if (task_pgrp(p->real_parent) != pgrp &&
337 task_session(p->real_parent) == task_session(p))
338 return 0;
339 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
340
341 return 1;
342}
343
344int is_current_pgrp_orphaned(void)
345{
346 int retval;
347
348 read_lock(&tasklist_lock);
349 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
350 read_unlock(&tasklist_lock);
351
352 return retval;
353}
354
355static bool has_stopped_jobs(struct pid *pgrp)
356{
357 struct task_struct *p;
358
359 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
360 if (p->signal->flags & SIGNAL_STOP_STOPPED)
361 return true;
362 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
363
364 return false;
365}
366
367/*
368 * Check to see if any process groups have become orphaned as
369 * a result of our exiting, and if they have any stopped jobs,
370 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
371 */
372static void
373kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
374{
375 struct pid *pgrp = task_pgrp(tsk);
376 struct task_struct *ignored_task = tsk;
377
378 if (!parent)
379 /* exit: our father is in a different pgrp than
380 * we are and we were the only connection outside.
381 */
382 parent = tsk->real_parent;
383 else
384 /* reparent: our child is in a different pgrp than
385 * we are, and it was the only connection outside.
386 */
387 ignored_task = NULL;
388
389 if (task_pgrp(parent) != pgrp &&
390 task_session(parent) == task_session(tsk) &&
391 will_become_orphaned_pgrp(pgrp, ignored_task) &&
392 has_stopped_jobs(pgrp)) {
393 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
394 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
395 }
396}
397
398static void coredump_task_exit(struct task_struct *tsk)
399{
400 struct core_state *core_state;
401
402 /*
403 * Serialize with any possible pending coredump.
404 * We must hold siglock around checking core_state
405 * and setting PF_POSTCOREDUMP. The core-inducing thread
406 * will increment ->nr_threads for each thread in the
407 * group without PF_POSTCOREDUMP set.
408 */
409 spin_lock_irq(&tsk->sighand->siglock);
410 tsk->flags |= PF_POSTCOREDUMP;
411 core_state = tsk->signal->core_state;
412 spin_unlock_irq(&tsk->sighand->siglock);
413 if (core_state) {
414 struct core_thread self;
415
416 self.task = current;
417 if (self.task->flags & PF_SIGNALED)
418 self.next = xchg(&core_state->dumper.next, &self);
419 else
420 self.task = NULL;
421 /*
422 * Implies mb(), the result of xchg() must be visible
423 * to core_state->dumper.
424 */
425 if (atomic_dec_and_test(&core_state->nr_threads))
426 complete(&core_state->startup);
427
428 for (;;) {
429 set_current_state(TASK_UNINTERRUPTIBLE|TASK_FREEZABLE);
430 if (!self.task) /* see coredump_finish() */
431 break;
432 schedule();
433 }
434 __set_current_state(TASK_RUNNING);
435 }
436}
437
438#ifdef CONFIG_MEMCG
439/*
440 * A task is exiting. If it owned this mm, find a new owner for the mm.
441 */
442void mm_update_next_owner(struct mm_struct *mm)
443{
444 struct task_struct *c, *g, *p = current;
445
446retry:
447 /*
448 * If the exiting or execing task is not the owner, it's
449 * someone else's problem.
450 */
451 if (mm->owner != p)
452 return;
453 /*
454 * The current owner is exiting/execing and there are no other
455 * candidates. Do not leave the mm pointing to a possibly
456 * freed task structure.
457 */
458 if (atomic_read(&mm->mm_users) <= 1) {
459 WRITE_ONCE(mm->owner, NULL);
460 return;
461 }
462
463 read_lock(&tasklist_lock);
464 /*
465 * Search in the children
466 */
467 list_for_each_entry(c, &p->children, sibling) {
468 if (c->mm == mm)
469 goto assign_new_owner;
470 }
471
472 /*
473 * Search in the siblings
474 */
475 list_for_each_entry(c, &p->real_parent->children, sibling) {
476 if (c->mm == mm)
477 goto assign_new_owner;
478 }
479
480 /*
481 * Search through everything else, we should not get here often.
482 */
483 for_each_process(g) {
484 if (g->flags & PF_KTHREAD)
485 continue;
486 for_each_thread(g, c) {
487 if (c->mm == mm)
488 goto assign_new_owner;
489 if (c->mm)
490 break;
491 }
492 }
493 read_unlock(&tasklist_lock);
494 /*
495 * We found no owner yet mm_users > 1: this implies that we are
496 * most likely racing with swapoff (try_to_unuse()) or /proc or
497 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
498 */
499 WRITE_ONCE(mm->owner, NULL);
500 return;
501
502assign_new_owner:
503 BUG_ON(c == p);
504 get_task_struct(c);
505 /*
506 * The task_lock protects c->mm from changing.
507 * We always want mm->owner->mm == mm
508 */
509 task_lock(c);
510 /*
511 * Delay read_unlock() till we have the task_lock()
512 * to ensure that c does not slip away underneath us
513 */
514 read_unlock(&tasklist_lock);
515 if (c->mm != mm) {
516 task_unlock(c);
517 put_task_struct(c);
518 goto retry;
519 }
520 WRITE_ONCE(mm->owner, c);
521 lru_gen_migrate_mm(mm);
522 task_unlock(c);
523 put_task_struct(c);
524}
525#endif /* CONFIG_MEMCG */
526
527/*
528 * Turn us into a lazy TLB process if we
529 * aren't already..
530 */
531static void exit_mm(void)
532{
533 struct mm_struct *mm = current->mm;
534
535 exit_mm_release(current, mm);
536 if (!mm)
537 return;
538 sync_mm_rss(mm);
539 mmap_read_lock(mm);
540 mmgrab(mm);
541 BUG_ON(mm != current->active_mm);
542 /* more a memory barrier than a real lock */
543 task_lock(current);
544 /*
545 * When a thread stops operating on an address space, the loop
546 * in membarrier_private_expedited() may not observe that
547 * tsk->mm, and the loop in membarrier_global_expedited() may
548 * not observe a MEMBARRIER_STATE_GLOBAL_EXPEDITED
549 * rq->membarrier_state, so those would not issue an IPI.
550 * Membarrier requires a memory barrier after accessing
551 * user-space memory, before clearing tsk->mm or the
552 * rq->membarrier_state.
553 */
554 smp_mb__after_spinlock();
555 local_irq_disable();
556 current->mm = NULL;
557 membarrier_update_current_mm(NULL);
558 enter_lazy_tlb(mm, current);
559 local_irq_enable();
560 task_unlock(current);
561 mmap_read_unlock(mm);
562 mm_update_next_owner(mm);
563 mmput(mm);
564 if (test_thread_flag(TIF_MEMDIE))
565 exit_oom_victim();
566}
567
568static struct task_struct *find_alive_thread(struct task_struct *p)
569{
570 struct task_struct *t;
571
572 for_each_thread(p, t) {
573 if (!(t->flags & PF_EXITING))
574 return t;
575 }
576 return NULL;
577}
578
579static struct task_struct *find_child_reaper(struct task_struct *father,
580 struct list_head *dead)
581 __releases(&tasklist_lock)
582 __acquires(&tasklist_lock)
583{
584 struct pid_namespace *pid_ns = task_active_pid_ns(father);
585 struct task_struct *reaper = pid_ns->child_reaper;
586 struct task_struct *p, *n;
587
588 if (likely(reaper != father))
589 return reaper;
590
591 reaper = find_alive_thread(father);
592 if (reaper) {
593 pid_ns->child_reaper = reaper;
594 return reaper;
595 }
596
597 write_unlock_irq(&tasklist_lock);
598
599 list_for_each_entry_safe(p, n, dead, ptrace_entry) {
600 list_del_init(&p->ptrace_entry);
601 release_task(p);
602 }
603
604 zap_pid_ns_processes(pid_ns);
605 write_lock_irq(&tasklist_lock);
606
607 return father;
608}
609
610/*
611 * When we die, we re-parent all our children, and try to:
612 * 1. give them to another thread in our thread group, if such a member exists
613 * 2. give it to the first ancestor process which prctl'd itself as a
614 * child_subreaper for its children (like a service manager)
615 * 3. give it to the init process (PID 1) in our pid namespace
616 */
617static struct task_struct *find_new_reaper(struct task_struct *father,
618 struct task_struct *child_reaper)
619{
620 struct task_struct *thread, *reaper;
621
622 thread = find_alive_thread(father);
623 if (thread)
624 return thread;
625
626 if (father->signal->has_child_subreaper) {
627 unsigned int ns_level = task_pid(father)->level;
628 /*
629 * Find the first ->is_child_subreaper ancestor in our pid_ns.
630 * We can't check reaper != child_reaper to ensure we do not
631 * cross the namespaces, the exiting parent could be injected
632 * by setns() + fork().
633 * We check pid->level, this is slightly more efficient than
634 * task_active_pid_ns(reaper) != task_active_pid_ns(father).
635 */
636 for (reaper = father->real_parent;
637 task_pid(reaper)->level == ns_level;
638 reaper = reaper->real_parent) {
639 if (reaper == &init_task)
640 break;
641 if (!reaper->signal->is_child_subreaper)
642 continue;
643 thread = find_alive_thread(reaper);
644 if (thread)
645 return thread;
646 }
647 }
648
649 return child_reaper;
650}
651
652/*
653* Any that need to be release_task'd are put on the @dead list.
654 */
655static void reparent_leader(struct task_struct *father, struct task_struct *p,
656 struct list_head *dead)
657{
658 if (unlikely(p->exit_state == EXIT_DEAD))
659 return;
660
661 /* We don't want people slaying init. */
662 p->exit_signal = SIGCHLD;
663
664 /* If it has exited notify the new parent about this child's death. */
665 if (!p->ptrace &&
666 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
667 if (do_notify_parent(p, p->exit_signal)) {
668 p->exit_state = EXIT_DEAD;
669 list_add(&p->ptrace_entry, dead);
670 }
671 }
672
673 kill_orphaned_pgrp(p, father);
674}
675
676/*
677 * This does two things:
678 *
679 * A. Make init inherit all the child processes
680 * B. Check to see if any process groups have become orphaned
681 * as a result of our exiting, and if they have any stopped
682 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
683 */
684static void forget_original_parent(struct task_struct *father,
685 struct list_head *dead)
686{
687 struct task_struct *p, *t, *reaper;
688
689 if (unlikely(!list_empty(&father->ptraced)))
690 exit_ptrace(father, dead);
691
692 /* Can drop and reacquire tasklist_lock */
693 reaper = find_child_reaper(father, dead);
694 if (list_empty(&father->children))
695 return;
696
697 reaper = find_new_reaper(father, reaper);
698 list_for_each_entry(p, &father->children, sibling) {
699 for_each_thread(p, t) {
700 RCU_INIT_POINTER(t->real_parent, reaper);
701 BUG_ON((!t->ptrace) != (rcu_access_pointer(t->parent) == father));
702 if (likely(!t->ptrace))
703 t->parent = t->real_parent;
704 if (t->pdeath_signal)
705 group_send_sig_info(t->pdeath_signal,
706 SEND_SIG_NOINFO, t,
707 PIDTYPE_TGID);
708 }
709 /*
710 * If this is a threaded reparent there is no need to
711 * notify anyone anything has happened.
712 */
713 if (!same_thread_group(reaper, father))
714 reparent_leader(father, p, dead);
715 }
716 list_splice_tail_init(&father->children, &reaper->children);
717}
718
719/*
720 * Send signals to all our closest relatives so that they know
721 * to properly mourn us..
722 */
723static void exit_notify(struct task_struct *tsk, int group_dead)
724{
725 bool autoreap;
726 struct task_struct *p, *n;
727 LIST_HEAD(dead);
728
729 write_lock_irq(&tasklist_lock);
730 forget_original_parent(tsk, &dead);
731
732 if (group_dead)
733 kill_orphaned_pgrp(tsk->group_leader, NULL);
734
735 tsk->exit_state = EXIT_ZOMBIE;
736 if (unlikely(tsk->ptrace)) {
737 int sig = thread_group_leader(tsk) &&
738 thread_group_empty(tsk) &&
739 !ptrace_reparented(tsk) ?
740 tsk->exit_signal : SIGCHLD;
741 autoreap = do_notify_parent(tsk, sig);
742 } else if (thread_group_leader(tsk)) {
743 autoreap = thread_group_empty(tsk) &&
744 do_notify_parent(tsk, tsk->exit_signal);
745 } else {
746 autoreap = true;
747 }
748
749 if (autoreap) {
750 tsk->exit_state = EXIT_DEAD;
751 list_add(&tsk->ptrace_entry, &dead);
752 }
753
754 /* mt-exec, de_thread() is waiting for group leader */
755 if (unlikely(tsk->signal->notify_count < 0))
756 wake_up_process(tsk->signal->group_exec_task);
757 write_unlock_irq(&tasklist_lock);
758
759 list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
760 list_del_init(&p->ptrace_entry);
761 release_task(p);
762 }
763}
764
765#ifdef CONFIG_DEBUG_STACK_USAGE
766static void check_stack_usage(void)
767{
768 static DEFINE_SPINLOCK(low_water_lock);
769 static int lowest_to_date = THREAD_SIZE;
770 unsigned long free;
771
772 free = stack_not_used(current);
773
774 if (free >= lowest_to_date)
775 return;
776
777 spin_lock(&low_water_lock);
778 if (free < lowest_to_date) {
779 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
780 current->comm, task_pid_nr(current), free);
781 lowest_to_date = free;
782 }
783 spin_unlock(&low_water_lock);
784}
785#else
786static inline void check_stack_usage(void) {}
787#endif
788
789static void synchronize_group_exit(struct task_struct *tsk, long code)
790{
791 struct sighand_struct *sighand = tsk->sighand;
792 struct signal_struct *signal = tsk->signal;
793
794 spin_lock_irq(&sighand->siglock);
795 signal->quick_threads--;
796 if ((signal->quick_threads == 0) &&
797 !(signal->flags & SIGNAL_GROUP_EXIT)) {
798 signal->flags = SIGNAL_GROUP_EXIT;
799 signal->group_exit_code = code;
800 signal->group_stop_count = 0;
801 }
802 spin_unlock_irq(&sighand->siglock);
803}
804
805void __noreturn do_exit(long code)
806{
807 struct task_struct *tsk = current;
808 int group_dead;
809
810 synchronize_group_exit(tsk, code);
811
812 WARN_ON(tsk->plug);
813
814 kcov_task_exit(tsk);
815 kmsan_task_exit(tsk);
816
817 coredump_task_exit(tsk);
818 ptrace_event(PTRACE_EVENT_EXIT, code);
819
820 validate_creds_for_do_exit(tsk);
821
822 io_uring_files_cancel();
823 exit_signals(tsk); /* sets PF_EXITING */
824
825 /* sync mm's RSS info before statistics gathering */
826 if (tsk->mm)
827 sync_mm_rss(tsk->mm);
828 acct_update_integrals(tsk);
829 group_dead = atomic_dec_and_test(&tsk->signal->live);
830 if (group_dead) {
831 /*
832 * If the last thread of global init has exited, panic
833 * immediately to get a useable coredump.
834 */
835 if (unlikely(is_global_init(tsk)))
836 panic("Attempted to kill init! exitcode=0x%08x\n",
837 tsk->signal->group_exit_code ?: (int)code);
838
839#ifdef CONFIG_POSIX_TIMERS
840 hrtimer_cancel(&tsk->signal->real_timer);
841 exit_itimers(tsk);
842#endif
843 if (tsk->mm)
844 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
845 }
846 acct_collect(code, group_dead);
847 if (group_dead)
848 tty_audit_exit();
849 audit_free(tsk);
850
851 tsk->exit_code = code;
852 taskstats_exit(tsk, group_dead);
853
854 exit_mm();
855
856 if (group_dead)
857 acct_process();
858 trace_sched_process_exit(tsk);
859
860 exit_sem(tsk);
861 exit_shm(tsk);
862 exit_files(tsk);
863 exit_fs(tsk);
864 if (group_dead)
865 disassociate_ctty(1);
866 exit_task_namespaces(tsk);
867 exit_task_work(tsk);
868 exit_thread(tsk);
869
870 /*
871 * Flush inherited counters to the parent - before the parent
872 * gets woken up by child-exit notifications.
873 *
874 * because of cgroup mode, must be called before cgroup_exit()
875 */
876 perf_event_exit_task(tsk);
877
878 sched_autogroup_exit_task(tsk);
879 cgroup_exit(tsk);
880
881 /*
882 * FIXME: do that only when needed, using sched_exit tracepoint
883 */
884 flush_ptrace_hw_breakpoint(tsk);
885
886 exit_tasks_rcu_start();
887 exit_notify(tsk, group_dead);
888 proc_exit_connector(tsk);
889 mpol_put_task_policy(tsk);
890#ifdef CONFIG_FUTEX
891 if (unlikely(current->pi_state_cache))
892 kfree(current->pi_state_cache);
893#endif
894 /*
895 * Make sure we are holding no locks:
896 */
897 debug_check_no_locks_held();
898
899 if (tsk->io_context)
900 exit_io_context(tsk);
901
902 if (tsk->splice_pipe)
903 free_pipe_info(tsk->splice_pipe);
904
905 if (tsk->task_frag.page)
906 put_page(tsk->task_frag.page);
907
908 validate_creds_for_do_exit(tsk);
909 exit_task_stack_account(tsk);
910
911 check_stack_usage();
912 preempt_disable();
913 if (tsk->nr_dirtied)
914 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
915 exit_rcu();
916 exit_tasks_rcu_finish();
917
918 lockdep_free_task(tsk);
919 do_task_dead();
920}
921
922void __noreturn make_task_dead(int signr)
923{
924 /*
925 * Take the task off the cpu after something catastrophic has
926 * happened.
927 *
928 * We can get here from a kernel oops, sometimes with preemption off.
929 * Start by checking for critical errors.
930 * Then fix up important state like USER_DS and preemption.
931 * Then do everything else.
932 */
933 struct task_struct *tsk = current;
934 unsigned int limit;
935
936 if (unlikely(in_interrupt()))
937 panic("Aiee, killing interrupt handler!");
938 if (unlikely(!tsk->pid))
939 panic("Attempted to kill the idle task!");
940
941 if (unlikely(in_atomic())) {
942 pr_info("note: %s[%d] exited with preempt_count %d\n",
943 current->comm, task_pid_nr(current),
944 preempt_count());
945 preempt_count_set(PREEMPT_ENABLED);
946 }
947
948 /*
949 * Every time the system oopses, if the oops happens while a reference
950 * to an object was held, the reference leaks.
951 * If the oops doesn't also leak memory, repeated oopsing can cause
952 * reference counters to wrap around (if they're not using refcount_t).
953 * This means that repeated oopsing can make unexploitable-looking bugs
954 * exploitable through repeated oopsing.
955 * To make sure this can't happen, place an upper bound on how often the
956 * kernel may oops without panic().
957 */
958 limit = READ_ONCE(oops_limit);
959 if (atomic_inc_return(&oops_count) >= limit && limit)
960 panic("Oopsed too often (kernel.oops_limit is %d)", limit);
961
962 /*
963 * We're taking recursive faults here in make_task_dead. Safest is to just
964 * leave this task alone and wait for reboot.
965 */
966 if (unlikely(tsk->flags & PF_EXITING)) {
967 pr_alert("Fixing recursive fault but reboot is needed!\n");
968 futex_exit_recursive(tsk);
969 tsk->exit_state = EXIT_DEAD;
970 refcount_inc(&tsk->rcu_users);
971 do_task_dead();
972 }
973
974 do_exit(signr);
975}
976
977SYSCALL_DEFINE1(exit, int, error_code)
978{
979 do_exit((error_code&0xff)<<8);
980}
981
982/*
983 * Take down every thread in the group. This is called by fatal signals
984 * as well as by sys_exit_group (below).
985 */
986void __noreturn
987do_group_exit(int exit_code)
988{
989 struct signal_struct *sig = current->signal;
990
991 if (sig->flags & SIGNAL_GROUP_EXIT)
992 exit_code = sig->group_exit_code;
993 else if (sig->group_exec_task)
994 exit_code = 0;
995 else {
996 struct sighand_struct *const sighand = current->sighand;
997
998 spin_lock_irq(&sighand->siglock);
999 if (sig->flags & SIGNAL_GROUP_EXIT)
1000 /* Another thread got here before we took the lock. */
1001 exit_code = sig->group_exit_code;
1002 else if (sig->group_exec_task)
1003 exit_code = 0;
1004 else {
1005 sig->group_exit_code = exit_code;
1006 sig->flags = SIGNAL_GROUP_EXIT;
1007 zap_other_threads(current);
1008 }
1009 spin_unlock_irq(&sighand->siglock);
1010 }
1011
1012 do_exit(exit_code);
1013 /* NOTREACHED */
1014}
1015
1016/*
1017 * this kills every thread in the thread group. Note that any externally
1018 * wait4()-ing process will get the correct exit code - even if this
1019 * thread is not the thread group leader.
1020 */
1021SYSCALL_DEFINE1(exit_group, int, error_code)
1022{
1023 do_group_exit((error_code & 0xff) << 8);
1024 /* NOTREACHED */
1025 return 0;
1026}
1027
1028struct waitid_info {
1029 pid_t pid;
1030 uid_t uid;
1031 int status;
1032 int cause;
1033};
1034
1035struct wait_opts {
1036 enum pid_type wo_type;
1037 int wo_flags;
1038 struct pid *wo_pid;
1039
1040 struct waitid_info *wo_info;
1041 int wo_stat;
1042 struct rusage *wo_rusage;
1043
1044 wait_queue_entry_t child_wait;
1045 int notask_error;
1046};
1047
1048static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
1049{
1050 return wo->wo_type == PIDTYPE_MAX ||
1051 task_pid_type(p, wo->wo_type) == wo->wo_pid;
1052}
1053
1054static int
1055eligible_child(struct wait_opts *wo, bool ptrace, struct task_struct *p)
1056{
1057 if (!eligible_pid(wo, p))
1058 return 0;
1059
1060 /*
1061 * Wait for all children (clone and not) if __WALL is set or
1062 * if it is traced by us.
1063 */
1064 if (ptrace || (wo->wo_flags & __WALL))
1065 return 1;
1066
1067 /*
1068 * Otherwise, wait for clone children *only* if __WCLONE is set;
1069 * otherwise, wait for non-clone children *only*.
1070 *
1071 * Note: a "clone" child here is one that reports to its parent
1072 * using a signal other than SIGCHLD, or a non-leader thread which
1073 * we can only see if it is traced by us.
1074 */
1075 if ((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
1076 return 0;
1077
1078 return 1;
1079}
1080
1081/*
1082 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1083 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1084 * the lock and this task is uninteresting. If we return nonzero, we have
1085 * released the lock and the system call should return.
1086 */
1087static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1088{
1089 int state, status;
1090 pid_t pid = task_pid_vnr(p);
1091 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1092 struct waitid_info *infop;
1093
1094 if (!likely(wo->wo_flags & WEXITED))
1095 return 0;
1096
1097 if (unlikely(wo->wo_flags & WNOWAIT)) {
1098 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1099 ? p->signal->group_exit_code : p->exit_code;
1100 get_task_struct(p);
1101 read_unlock(&tasklist_lock);
1102 sched_annotate_sleep();
1103 if (wo->wo_rusage)
1104 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1105 put_task_struct(p);
1106 goto out_info;
1107 }
1108 /*
1109 * Move the task's state to DEAD/TRACE, only one thread can do this.
1110 */
1111 state = (ptrace_reparented(p) && thread_group_leader(p)) ?
1112 EXIT_TRACE : EXIT_DEAD;
1113 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1114 return 0;
1115 /*
1116 * We own this thread, nobody else can reap it.
1117 */
1118 read_unlock(&tasklist_lock);
1119 sched_annotate_sleep();
1120
1121 /*
1122 * Check thread_group_leader() to exclude the traced sub-threads.
1123 */
1124 if (state == EXIT_DEAD && thread_group_leader(p)) {
1125 struct signal_struct *sig = p->signal;
1126 struct signal_struct *psig = current->signal;
1127 unsigned long maxrss;
1128 u64 tgutime, tgstime;
1129
1130 /*
1131 * The resource counters for the group leader are in its
1132 * own task_struct. Those for dead threads in the group
1133 * are in its signal_struct, as are those for the child
1134 * processes it has previously reaped. All these
1135 * accumulate in the parent's signal_struct c* fields.
1136 *
1137 * We don't bother to take a lock here to protect these
1138 * p->signal fields because the whole thread group is dead
1139 * and nobody can change them.
1140 *
1141 * psig->stats_lock also protects us from our sub-threads
1142 * which can reap other children at the same time. Until
1143 * we change k_getrusage()-like users to rely on this lock
1144 * we have to take ->siglock as well.
1145 *
1146 * We use thread_group_cputime_adjusted() to get times for
1147 * the thread group, which consolidates times for all threads
1148 * in the group including the group leader.
1149 */
1150 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1151 spin_lock_irq(¤t->sighand->siglock);
1152 write_seqlock(&psig->stats_lock);
1153 psig->cutime += tgutime + sig->cutime;
1154 psig->cstime += tgstime + sig->cstime;
1155 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1156 psig->cmin_flt +=
1157 p->min_flt + sig->min_flt + sig->cmin_flt;
1158 psig->cmaj_flt +=
1159 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1160 psig->cnvcsw +=
1161 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1162 psig->cnivcsw +=
1163 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1164 psig->cinblock +=
1165 task_io_get_inblock(p) +
1166 sig->inblock + sig->cinblock;
1167 psig->coublock +=
1168 task_io_get_oublock(p) +
1169 sig->oublock + sig->coublock;
1170 maxrss = max(sig->maxrss, sig->cmaxrss);
1171 if (psig->cmaxrss < maxrss)
1172 psig->cmaxrss = maxrss;
1173 task_io_accounting_add(&psig->ioac, &p->ioac);
1174 task_io_accounting_add(&psig->ioac, &sig->ioac);
1175 write_sequnlock(&psig->stats_lock);
1176 spin_unlock_irq(¤t->sighand->siglock);
1177 }
1178
1179 if (wo->wo_rusage)
1180 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1181 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1182 ? p->signal->group_exit_code : p->exit_code;
1183 wo->wo_stat = status;
1184
1185 if (state == EXIT_TRACE) {
1186 write_lock_irq(&tasklist_lock);
1187 /* We dropped tasklist, ptracer could die and untrace */
1188 ptrace_unlink(p);
1189
1190 /* If parent wants a zombie, don't release it now */
1191 state = EXIT_ZOMBIE;
1192 if (do_notify_parent(p, p->exit_signal))
1193 state = EXIT_DEAD;
1194 p->exit_state = state;
1195 write_unlock_irq(&tasklist_lock);
1196 }
1197 if (state == EXIT_DEAD)
1198 release_task(p);
1199
1200out_info:
1201 infop = wo->wo_info;
1202 if (infop) {
1203 if ((status & 0x7f) == 0) {
1204 infop->cause = CLD_EXITED;
1205 infop->status = status >> 8;
1206 } else {
1207 infop->cause = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1208 infop->status = status & 0x7f;
1209 }
1210 infop->pid = pid;
1211 infop->uid = uid;
1212 }
1213
1214 return pid;
1215}
1216
1217static int *task_stopped_code(struct task_struct *p, bool ptrace)
1218{
1219 if (ptrace) {
1220 if (task_is_traced(p) && !(p->jobctl & JOBCTL_LISTENING))
1221 return &p->exit_code;
1222 } else {
1223 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1224 return &p->signal->group_exit_code;
1225 }
1226 return NULL;
1227}
1228
1229/**
1230 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1231 * @wo: wait options
1232 * @ptrace: is the wait for ptrace
1233 * @p: task to wait for
1234 *
1235 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1236 *
1237 * CONTEXT:
1238 * read_lock(&tasklist_lock), which is released if return value is
1239 * non-zero. Also, grabs and releases @p->sighand->siglock.
1240 *
1241 * RETURNS:
1242 * 0 if wait condition didn't exist and search for other wait conditions
1243 * should continue. Non-zero return, -errno on failure and @p's pid on
1244 * success, implies that tasklist_lock is released and wait condition
1245 * search should terminate.
1246 */
1247static int wait_task_stopped(struct wait_opts *wo,
1248 int ptrace, struct task_struct *p)
1249{
1250 struct waitid_info *infop;
1251 int exit_code, *p_code, why;
1252 uid_t uid = 0; /* unneeded, required by compiler */
1253 pid_t pid;
1254
1255 /*
1256 * Traditionally we see ptrace'd stopped tasks regardless of options.
1257 */
1258 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1259 return 0;
1260
1261 if (!task_stopped_code(p, ptrace))
1262 return 0;
1263
1264 exit_code = 0;
1265 spin_lock_irq(&p->sighand->siglock);
1266
1267 p_code = task_stopped_code(p, ptrace);
1268 if (unlikely(!p_code))
1269 goto unlock_sig;
1270
1271 exit_code = *p_code;
1272 if (!exit_code)
1273 goto unlock_sig;
1274
1275 if (!unlikely(wo->wo_flags & WNOWAIT))
1276 *p_code = 0;
1277
1278 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1279unlock_sig:
1280 spin_unlock_irq(&p->sighand->siglock);
1281 if (!exit_code)
1282 return 0;
1283
1284 /*
1285 * Now we are pretty sure this task is interesting.
1286 * Make sure it doesn't get reaped out from under us while we
1287 * give up the lock and then examine it below. We don't want to
1288 * keep holding onto the tasklist_lock while we call getrusage and
1289 * possibly take page faults for user memory.
1290 */
1291 get_task_struct(p);
1292 pid = task_pid_vnr(p);
1293 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1294 read_unlock(&tasklist_lock);
1295 sched_annotate_sleep();
1296 if (wo->wo_rusage)
1297 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1298 put_task_struct(p);
1299
1300 if (likely(!(wo->wo_flags & WNOWAIT)))
1301 wo->wo_stat = (exit_code << 8) | 0x7f;
1302
1303 infop = wo->wo_info;
1304 if (infop) {
1305 infop->cause = why;
1306 infop->status = exit_code;
1307 infop->pid = pid;
1308 infop->uid = uid;
1309 }
1310 return pid;
1311}
1312
1313/*
1314 * Handle do_wait work for one task in a live, non-stopped state.
1315 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1316 * the lock and this task is uninteresting. If we return nonzero, we have
1317 * released the lock and the system call should return.
1318 */
1319static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1320{
1321 struct waitid_info *infop;
1322 pid_t pid;
1323 uid_t uid;
1324
1325 if (!unlikely(wo->wo_flags & WCONTINUED))
1326 return 0;
1327
1328 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1329 return 0;
1330
1331 spin_lock_irq(&p->sighand->siglock);
1332 /* Re-check with the lock held. */
1333 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1334 spin_unlock_irq(&p->sighand->siglock);
1335 return 0;
1336 }
1337 if (!unlikely(wo->wo_flags & WNOWAIT))
1338 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1339 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1340 spin_unlock_irq(&p->sighand->siglock);
1341
1342 pid = task_pid_vnr(p);
1343 get_task_struct(p);
1344 read_unlock(&tasklist_lock);
1345 sched_annotate_sleep();
1346 if (wo->wo_rusage)
1347 getrusage(p, RUSAGE_BOTH, wo->wo_rusage);
1348 put_task_struct(p);
1349
1350 infop = wo->wo_info;
1351 if (!infop) {
1352 wo->wo_stat = 0xffff;
1353 } else {
1354 infop->cause = CLD_CONTINUED;
1355 infop->pid = pid;
1356 infop->uid = uid;
1357 infop->status = SIGCONT;
1358 }
1359 return pid;
1360}
1361
1362/*
1363 * Consider @p for a wait by @parent.
1364 *
1365 * -ECHILD should be in ->notask_error before the first call.
1366 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1367 * Returns zero if the search for a child should continue;
1368 * then ->notask_error is 0 if @p is an eligible child,
1369 * or still -ECHILD.
1370 */
1371static int wait_consider_task(struct wait_opts *wo, int ptrace,
1372 struct task_struct *p)
1373{
1374 /*
1375 * We can race with wait_task_zombie() from another thread.
1376 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1377 * can't confuse the checks below.
1378 */
1379 int exit_state = READ_ONCE(p->exit_state);
1380 int ret;
1381
1382 if (unlikely(exit_state == EXIT_DEAD))
1383 return 0;
1384
1385 ret = eligible_child(wo, ptrace, p);
1386 if (!ret)
1387 return ret;
1388
1389 if (unlikely(exit_state == EXIT_TRACE)) {
1390 /*
1391 * ptrace == 0 means we are the natural parent. In this case
1392 * we should clear notask_error, debugger will notify us.
1393 */
1394 if (likely(!ptrace))
1395 wo->notask_error = 0;
1396 return 0;
1397 }
1398
1399 if (likely(!ptrace) && unlikely(p->ptrace)) {
1400 /*
1401 * If it is traced by its real parent's group, just pretend
1402 * the caller is ptrace_do_wait() and reap this child if it
1403 * is zombie.
1404 *
1405 * This also hides group stop state from real parent; otherwise
1406 * a single stop can be reported twice as group and ptrace stop.
1407 * If a ptracer wants to distinguish these two events for its
1408 * own children it should create a separate process which takes
1409 * the role of real parent.
1410 */
1411 if (!ptrace_reparented(p))
1412 ptrace = 1;
1413 }
1414
1415 /* slay zombie? */
1416 if (exit_state == EXIT_ZOMBIE) {
1417 /* we don't reap group leaders with subthreads */
1418 if (!delay_group_leader(p)) {
1419 /*
1420 * A zombie ptracee is only visible to its ptracer.
1421 * Notification and reaping will be cascaded to the
1422 * real parent when the ptracer detaches.
1423 */
1424 if (unlikely(ptrace) || likely(!p->ptrace))
1425 return wait_task_zombie(wo, p);
1426 }
1427
1428 /*
1429 * Allow access to stopped/continued state via zombie by
1430 * falling through. Clearing of notask_error is complex.
1431 *
1432 * When !@ptrace:
1433 *
1434 * If WEXITED is set, notask_error should naturally be
1435 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1436 * so, if there are live subthreads, there are events to
1437 * wait for. If all subthreads are dead, it's still safe
1438 * to clear - this function will be called again in finite
1439 * amount time once all the subthreads are released and
1440 * will then return without clearing.
1441 *
1442 * When @ptrace:
1443 *
1444 * Stopped state is per-task and thus can't change once the
1445 * target task dies. Only continued and exited can happen.
1446 * Clear notask_error if WCONTINUED | WEXITED.
1447 */
1448 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1449 wo->notask_error = 0;
1450 } else {
1451 /*
1452 * @p is alive and it's gonna stop, continue or exit, so
1453 * there always is something to wait for.
1454 */
1455 wo->notask_error = 0;
1456 }
1457
1458 /*
1459 * Wait for stopped. Depending on @ptrace, different stopped state
1460 * is used and the two don't interact with each other.
1461 */
1462 ret = wait_task_stopped(wo, ptrace, p);
1463 if (ret)
1464 return ret;
1465
1466 /*
1467 * Wait for continued. There's only one continued state and the
1468 * ptracer can consume it which can confuse the real parent. Don't
1469 * use WCONTINUED from ptracer. You don't need or want it.
1470 */
1471 return wait_task_continued(wo, p);
1472}
1473
1474/*
1475 * Do the work of do_wait() for one thread in the group, @tsk.
1476 *
1477 * -ECHILD should be in ->notask_error before the first call.
1478 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1479 * Returns zero if the search for a child should continue; then
1480 * ->notask_error is 0 if there were any eligible children,
1481 * or still -ECHILD.
1482 */
1483static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1484{
1485 struct task_struct *p;
1486
1487 list_for_each_entry(p, &tsk->children, sibling) {
1488 int ret = wait_consider_task(wo, 0, p);
1489
1490 if (ret)
1491 return ret;
1492 }
1493
1494 return 0;
1495}
1496
1497static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1498{
1499 struct task_struct *p;
1500
1501 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1502 int ret = wait_consider_task(wo, 1, p);
1503
1504 if (ret)
1505 return ret;
1506 }
1507
1508 return 0;
1509}
1510
1511static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode,
1512 int sync, void *key)
1513{
1514 struct wait_opts *wo = container_of(wait, struct wait_opts,
1515 child_wait);
1516 struct task_struct *p = key;
1517
1518 if (!eligible_pid(wo, p))
1519 return 0;
1520
1521 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1522 return 0;
1523
1524 return default_wake_function(wait, mode, sync, key);
1525}
1526
1527void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1528{
1529 __wake_up_sync_key(&parent->signal->wait_chldexit,
1530 TASK_INTERRUPTIBLE, p);
1531}
1532
1533static bool is_effectively_child(struct wait_opts *wo, bool ptrace,
1534 struct task_struct *target)
1535{
1536 struct task_struct *parent =
1537 !ptrace ? target->real_parent : target->parent;
1538
1539 return current == parent || (!(wo->wo_flags & __WNOTHREAD) &&
1540 same_thread_group(current, parent));
1541}
1542
1543/*
1544 * Optimization for waiting on PIDTYPE_PID. No need to iterate through child
1545 * and tracee lists to find the target task.
1546 */
1547static int do_wait_pid(struct wait_opts *wo)
1548{
1549 bool ptrace;
1550 struct task_struct *target;
1551 int retval;
1552
1553 ptrace = false;
1554 target = pid_task(wo->wo_pid, PIDTYPE_TGID);
1555 if (target && is_effectively_child(wo, ptrace, target)) {
1556 retval = wait_consider_task(wo, ptrace, target);
1557 if (retval)
1558 return retval;
1559 }
1560
1561 ptrace = true;
1562 target = pid_task(wo->wo_pid, PIDTYPE_PID);
1563 if (target && target->ptrace &&
1564 is_effectively_child(wo, ptrace, target)) {
1565 retval = wait_consider_task(wo, ptrace, target);
1566 if (retval)
1567 return retval;
1568 }
1569
1570 return 0;
1571}
1572
1573static long do_wait(struct wait_opts *wo)
1574{
1575 int retval;
1576
1577 trace_sched_process_wait(wo->wo_pid);
1578
1579 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1580 wo->child_wait.private = current;
1581 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1582repeat:
1583 /*
1584 * If there is nothing that can match our criteria, just get out.
1585 * We will clear ->notask_error to zero if we see any child that
1586 * might later match our criteria, even if we are not able to reap
1587 * it yet.
1588 */
1589 wo->notask_error = -ECHILD;
1590 if ((wo->wo_type < PIDTYPE_MAX) &&
1591 (!wo->wo_pid || !pid_has_task(wo->wo_pid, wo->wo_type)))
1592 goto notask;
1593
1594 set_current_state(TASK_INTERRUPTIBLE);
1595 read_lock(&tasklist_lock);
1596
1597 if (wo->wo_type == PIDTYPE_PID) {
1598 retval = do_wait_pid(wo);
1599 if (retval)
1600 goto end;
1601 } else {
1602 struct task_struct *tsk = current;
1603
1604 do {
1605 retval = do_wait_thread(wo, tsk);
1606 if (retval)
1607 goto end;
1608
1609 retval = ptrace_do_wait(wo, tsk);
1610 if (retval)
1611 goto end;
1612
1613 if (wo->wo_flags & __WNOTHREAD)
1614 break;
1615 } while_each_thread(current, tsk);
1616 }
1617 read_unlock(&tasklist_lock);
1618
1619notask:
1620 retval = wo->notask_error;
1621 if (!retval && !(wo->wo_flags & WNOHANG)) {
1622 retval = -ERESTARTSYS;
1623 if (!signal_pending(current)) {
1624 schedule();
1625 goto repeat;
1626 }
1627 }
1628end:
1629 __set_current_state(TASK_RUNNING);
1630 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1631 return retval;
1632}
1633
1634static long kernel_waitid(int which, pid_t upid, struct waitid_info *infop,
1635 int options, struct rusage *ru)
1636{
1637 struct wait_opts wo;
1638 struct pid *pid = NULL;
1639 enum pid_type type;
1640 long ret;
1641 unsigned int f_flags = 0;
1642
1643 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED|
1644 __WNOTHREAD|__WCLONE|__WALL))
1645 return -EINVAL;
1646 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1647 return -EINVAL;
1648
1649 switch (which) {
1650 case P_ALL:
1651 type = PIDTYPE_MAX;
1652 break;
1653 case P_PID:
1654 type = PIDTYPE_PID;
1655 if (upid <= 0)
1656 return -EINVAL;
1657
1658 pid = find_get_pid(upid);
1659 break;
1660 case P_PGID:
1661 type = PIDTYPE_PGID;
1662 if (upid < 0)
1663 return -EINVAL;
1664
1665 if (upid)
1666 pid = find_get_pid(upid);
1667 else
1668 pid = get_task_pid(current, PIDTYPE_PGID);
1669 break;
1670 case P_PIDFD:
1671 type = PIDTYPE_PID;
1672 if (upid < 0)
1673 return -EINVAL;
1674
1675 pid = pidfd_get_pid(upid, &f_flags);
1676 if (IS_ERR(pid))
1677 return PTR_ERR(pid);
1678
1679 break;
1680 default:
1681 return -EINVAL;
1682 }
1683
1684 wo.wo_type = type;
1685 wo.wo_pid = pid;
1686 wo.wo_flags = options;
1687 wo.wo_info = infop;
1688 wo.wo_rusage = ru;
1689 if (f_flags & O_NONBLOCK)
1690 wo.wo_flags |= WNOHANG;
1691
1692 ret = do_wait(&wo);
1693 if (!ret && !(options & WNOHANG) && (f_flags & O_NONBLOCK))
1694 ret = -EAGAIN;
1695
1696 put_pid(pid);
1697 return ret;
1698}
1699
1700SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1701 infop, int, options, struct rusage __user *, ru)
1702{
1703 struct rusage r;
1704 struct waitid_info info = {.status = 0};
1705 long err = kernel_waitid(which, upid, &info, options, ru ? &r : NULL);
1706 int signo = 0;
1707
1708 if (err > 0) {
1709 signo = SIGCHLD;
1710 err = 0;
1711 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1712 return -EFAULT;
1713 }
1714 if (!infop)
1715 return err;
1716
1717 if (!user_write_access_begin(infop, sizeof(*infop)))
1718 return -EFAULT;
1719
1720 unsafe_put_user(signo, &infop->si_signo, Efault);
1721 unsafe_put_user(0, &infop->si_errno, Efault);
1722 unsafe_put_user(info.cause, &infop->si_code, Efault);
1723 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1724 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1725 unsafe_put_user(info.status, &infop->si_status, Efault);
1726 user_write_access_end();
1727 return err;
1728Efault:
1729 user_write_access_end();
1730 return -EFAULT;
1731}
1732
1733long kernel_wait4(pid_t upid, int __user *stat_addr, int options,
1734 struct rusage *ru)
1735{
1736 struct wait_opts wo;
1737 struct pid *pid = NULL;
1738 enum pid_type type;
1739 long ret;
1740
1741 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1742 __WNOTHREAD|__WCLONE|__WALL))
1743 return -EINVAL;
1744
1745 /* -INT_MIN is not defined */
1746 if (upid == INT_MIN)
1747 return -ESRCH;
1748
1749 if (upid == -1)
1750 type = PIDTYPE_MAX;
1751 else if (upid < 0) {
1752 type = PIDTYPE_PGID;
1753 pid = find_get_pid(-upid);
1754 } else if (upid == 0) {
1755 type = PIDTYPE_PGID;
1756 pid = get_task_pid(current, PIDTYPE_PGID);
1757 } else /* upid > 0 */ {
1758 type = PIDTYPE_PID;
1759 pid = find_get_pid(upid);
1760 }
1761
1762 wo.wo_type = type;
1763 wo.wo_pid = pid;
1764 wo.wo_flags = options | WEXITED;
1765 wo.wo_info = NULL;
1766 wo.wo_stat = 0;
1767 wo.wo_rusage = ru;
1768 ret = do_wait(&wo);
1769 put_pid(pid);
1770 if (ret > 0 && stat_addr && put_user(wo.wo_stat, stat_addr))
1771 ret = -EFAULT;
1772
1773 return ret;
1774}
1775
1776int kernel_wait(pid_t pid, int *stat)
1777{
1778 struct wait_opts wo = {
1779 .wo_type = PIDTYPE_PID,
1780 .wo_pid = find_get_pid(pid),
1781 .wo_flags = WEXITED,
1782 };
1783 int ret;
1784
1785 ret = do_wait(&wo);
1786 if (ret > 0 && wo.wo_stat)
1787 *stat = wo.wo_stat;
1788 put_pid(wo.wo_pid);
1789 return ret;
1790}
1791
1792SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1793 int, options, struct rusage __user *, ru)
1794{
1795 struct rusage r;
1796 long err = kernel_wait4(upid, stat_addr, options, ru ? &r : NULL);
1797
1798 if (err > 0) {
1799 if (ru && copy_to_user(ru, &r, sizeof(struct rusage)))
1800 return -EFAULT;
1801 }
1802 return err;
1803}
1804
1805#ifdef __ARCH_WANT_SYS_WAITPID
1806
1807/*
1808 * sys_waitpid() remains for compatibility. waitpid() should be
1809 * implemented by calling sys_wait4() from libc.a.
1810 */
1811SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1812{
1813 return kernel_wait4(pid, stat_addr, options, NULL);
1814}
1815
1816#endif
1817
1818#ifdef CONFIG_COMPAT
1819COMPAT_SYSCALL_DEFINE4(wait4,
1820 compat_pid_t, pid,
1821 compat_uint_t __user *, stat_addr,
1822 int, options,
1823 struct compat_rusage __user *, ru)
1824{
1825 struct rusage r;
1826 long err = kernel_wait4(pid, stat_addr, options, ru ? &r : NULL);
1827 if (err > 0) {
1828 if (ru && put_compat_rusage(&r, ru))
1829 return -EFAULT;
1830 }
1831 return err;
1832}
1833
1834COMPAT_SYSCALL_DEFINE5(waitid,
1835 int, which, compat_pid_t, pid,
1836 struct compat_siginfo __user *, infop, int, options,
1837 struct compat_rusage __user *, uru)
1838{
1839 struct rusage ru;
1840 struct waitid_info info = {.status = 0};
1841 long err = kernel_waitid(which, pid, &info, options, uru ? &ru : NULL);
1842 int signo = 0;
1843 if (err > 0) {
1844 signo = SIGCHLD;
1845 err = 0;
1846 if (uru) {
1847 /* kernel_waitid() overwrites everything in ru */
1848 if (COMPAT_USE_64BIT_TIME)
1849 err = copy_to_user(uru, &ru, sizeof(ru));
1850 else
1851 err = put_compat_rusage(&ru, uru);
1852 if (err)
1853 return -EFAULT;
1854 }
1855 }
1856
1857 if (!infop)
1858 return err;
1859
1860 if (!user_write_access_begin(infop, sizeof(*infop)))
1861 return -EFAULT;
1862
1863 unsafe_put_user(signo, &infop->si_signo, Efault);
1864 unsafe_put_user(0, &infop->si_errno, Efault);
1865 unsafe_put_user(info.cause, &infop->si_code, Efault);
1866 unsafe_put_user(info.pid, &infop->si_pid, Efault);
1867 unsafe_put_user(info.uid, &infop->si_uid, Efault);
1868 unsafe_put_user(info.status, &infop->si_status, Efault);
1869 user_write_access_end();
1870 return err;
1871Efault:
1872 user_write_access_end();
1873 return -EFAULT;
1874}
1875#endif
1876
1877/**
1878 * thread_group_exited - check that a thread group has exited
1879 * @pid: tgid of thread group to be checked.
1880 *
1881 * Test if the thread group represented by tgid has exited (all
1882 * threads are zombies, dead or completely gone).
1883 *
1884 * Return: true if the thread group has exited. false otherwise.
1885 */
1886bool thread_group_exited(struct pid *pid)
1887{
1888 struct task_struct *task;
1889 bool exited;
1890
1891 rcu_read_lock();
1892 task = pid_task(pid, PIDTYPE_PID);
1893 exited = !task ||
1894 (READ_ONCE(task->exit_state) && thread_group_empty(task));
1895 rcu_read_unlock();
1896
1897 return exited;
1898}
1899EXPORT_SYMBOL(thread_group_exited);
1900
1901__weak void abort(void)
1902{
1903 BUG();
1904
1905 /* if that doesn't kill us, halt */
1906 panic("Oops failed to kill thread");
1907}
1908EXPORT_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