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Root/kernel/exit.c

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

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