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1/*
2 * linux/kernel/exit.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7#include <linux/mm.h>
8#include <linux/slab.h>
9#include <linux/interrupt.h>
10#include <linux/module.h>
11#include <linux/capability.h>
12#include <linux/completion.h>
13#include <linux/personality.h>
14#include <linux/tty.h>
15#include <linux/iocontext.h>
16#include <linux/key.h>
17#include <linux/security.h>
18#include <linux/cpu.h>
19#include <linux/acct.h>
20#include <linux/tsacct_kern.h>
21#include <linux/file.h>
22#include <linux/fdtable.h>
23#include <linux/freezer.h>
24#include <linux/binfmts.h>
25#include <linux/nsproxy.h>
26#include <linux/pid_namespace.h>
27#include <linux/ptrace.h>
28#include <linux/profile.h>
29#include <linux/mount.h>
30#include <linux/proc_fs.h>
31#include <linux/kthread.h>
32#include <linux/mempolicy.h>
33#include <linux/taskstats_kern.h>
34#include <linux/delayacct.h>
35#include <linux/cgroup.h>
36#include <linux/syscalls.h>
37#include <linux/signal.h>
38#include <linux/posix-timers.h>
39#include <linux/cn_proc.h>
40#include <linux/mutex.h>
41#include <linux/futex.h>
42#include <linux/pipe_fs_i.h>
43#include <linux/audit.h> /* for audit_free() */
44#include <linux/resource.h>
45#include <linux/blkdev.h>
46#include <linux/task_io_accounting_ops.h>
47#include <linux/tracehook.h>
48#include <linux/fs_struct.h>
49#include <linux/init_task.h>
50#include <linux/perf_event.h>
51#include <trace/events/sched.h>
52#include <linux/hw_breakpoint.h>
53#include <linux/oom.h>
54#include <linux/writeback.h>
55#include <linux/shm.h>
56
57#include <asm/uaccess.h>
58#include <asm/unistd.h>
59#include <asm/pgtable.h>
60#include <asm/mmu_context.h>
61
62static void exit_mm(struct task_struct * tsk);
63
64static void __unhash_process(struct task_struct *p, bool group_dead)
65{
66 nr_threads--;
67 detach_pid(p, PIDTYPE_PID);
68 if (group_dead) {
69 detach_pid(p, PIDTYPE_PGID);
70 detach_pid(p, PIDTYPE_SID);
71
72 list_del_rcu(&p->tasks);
73 list_del_init(&p->sibling);
74 __this_cpu_dec(process_counts);
75 }
76 list_del_rcu(&p->thread_group);
77 list_del_rcu(&p->thread_node);
78}
79
80/*
81 * This function expects the tasklist_lock write-locked.
82 */
83static void __exit_signal(struct task_struct *tsk)
84{
85 struct signal_struct *sig = tsk->signal;
86 bool group_dead = thread_group_leader(tsk);
87 struct sighand_struct *sighand;
88 struct tty_struct *uninitialized_var(tty);
89 cputime_t utime, stime;
90
91 sighand = rcu_dereference_check(tsk->sighand,
92 lockdep_tasklist_lock_is_held());
93 spin_lock(&sighand->siglock);
94
95 posix_cpu_timers_exit(tsk);
96 if (group_dead) {
97 posix_cpu_timers_exit_group(tsk);
98 tty = sig->tty;
99 sig->tty = NULL;
100 } else {
101 /*
102 * This can only happen if the caller is de_thread().
103 * FIXME: this is the temporary hack, we should teach
104 * posix-cpu-timers to handle this case correctly.
105 */
106 if (unlikely(has_group_leader_pid(tsk)))
107 posix_cpu_timers_exit_group(tsk);
108
109 /*
110 * If there is any task waiting for the group exit
111 * then notify it:
112 */
113 if (sig->notify_count > 0 && !--sig->notify_count)
114 wake_up_process(sig->group_exit_task);
115
116 if (tsk == sig->curr_target)
117 sig->curr_target = next_thread(tsk);
118 /*
119 * Accumulate here the counters for all threads but the
120 * group leader as they die, so they can be added into
121 * the process-wide totals when those are taken.
122 * The group leader stays around as a zombie as long
123 * as there are other threads. When it gets reaped,
124 * the exit.c code will add its counts into these totals.
125 * We won't ever get here for the group leader, since it
126 * will have been the last reference on the signal_struct.
127 */
128 task_cputime(tsk, &utime, &stime);
129 sig->utime += utime;
130 sig->stime += stime;
131 sig->gtime += task_gtime(tsk);
132 sig->min_flt += tsk->min_flt;
133 sig->maj_flt += tsk->maj_flt;
134 sig->nvcsw += tsk->nvcsw;
135 sig->nivcsw += tsk->nivcsw;
136 sig->inblock += task_io_get_inblock(tsk);
137 sig->oublock += task_io_get_oublock(tsk);
138 task_io_accounting_add(&sig->ioac, &tsk->ioac);
139 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
140 }
141
142 sig->nr_threads--;
143 __unhash_process(tsk, group_dead);
144
145 /*
146 * Do this under ->siglock, we can race with another thread
147 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
148 */
149 flush_sigqueue(&tsk->pending);
150 tsk->sighand = NULL;
151 spin_unlock(&sighand->siglock);
152
153 __cleanup_sighand(sighand);
154 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
155 if (group_dead) {
156 flush_sigqueue(&sig->shared_pending);
157 tty_kref_put(tty);
158 }
159}
160
161static void delayed_put_task_struct(struct rcu_head *rhp)
162{
163 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
164
165 perf_event_delayed_put(tsk);
166 trace_sched_process_free(tsk);
167 put_task_struct(tsk);
168}
169
170
171void release_task(struct task_struct * p)
172{
173 struct task_struct *leader;
174 int zap_leader;
175repeat:
176 /* don't need to get the RCU readlock here - the process is dead and
177 * can't be modifying its own credentials. But shut RCU-lockdep up */
178 rcu_read_lock();
179 atomic_dec(&__task_cred(p)->user->processes);
180 rcu_read_unlock();
181
182 proc_flush_task(p);
183
184 write_lock_irq(&tasklist_lock);
185 ptrace_release_task(p);
186 __exit_signal(p);
187
188 /*
189 * If we are the last non-leader member of the thread
190 * group, and the leader is zombie, then notify the
191 * group leader's parent process. (if it wants notification.)
192 */
193 zap_leader = 0;
194 leader = p->group_leader;
195 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
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 zap_leader = do_notify_parent(leader, leader->exit_signal);
202 if (zap_leader)
203 leader->exit_state = EXIT_DEAD;
204 }
205
206 write_unlock_irq(&tasklist_lock);
207 release_thread(p);
208 call_rcu(&p->rcu, delayed_put_task_struct);
209
210 p = leader;
211 if (unlikely(zap_leader))
212 goto repeat;
213}
214
215/*
216 * This checks not only the pgrp, but falls back on the pid if no
217 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
218 * without this...
219 *
220 * The caller must hold rcu lock or the tasklist lock.
221 */
222struct pid *session_of_pgrp(struct pid *pgrp)
223{
224 struct task_struct *p;
225 struct pid *sid = NULL;
226
227 p = pid_task(pgrp, PIDTYPE_PGID);
228 if (p == NULL)
229 p = pid_task(pgrp, PIDTYPE_PID);
230 if (p != NULL)
231 sid = task_session(p);
232
233 return sid;
234}
235
236/*
237 * Determine if a process group is "orphaned", according to the POSIX
238 * definition in 2.2.2.52. Orphaned process groups are not to be affected
239 * by terminal-generated stop signals. Newly orphaned process groups are
240 * to receive a SIGHUP and a SIGCONT.
241 *
242 * "I ask you, have you ever known what it is to be an orphan?"
243 */
244static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
245{
246 struct task_struct *p;
247
248 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
249 if ((p == ignored_task) ||
250 (p->exit_state && thread_group_empty(p)) ||
251 is_global_init(p->real_parent))
252 continue;
253
254 if (task_pgrp(p->real_parent) != pgrp &&
255 task_session(p->real_parent) == task_session(p))
256 return 0;
257 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
258
259 return 1;
260}
261
262int is_current_pgrp_orphaned(void)
263{
264 int retval;
265
266 read_lock(&tasklist_lock);
267 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
268 read_unlock(&tasklist_lock);
269
270 return retval;
271}
272
273static bool has_stopped_jobs(struct pid *pgrp)
274{
275 struct task_struct *p;
276
277 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
278 if (p->signal->flags & SIGNAL_STOP_STOPPED)
279 return true;
280 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
281
282 return false;
283}
284
285/*
286 * Check to see if any process groups have become orphaned as
287 * a result of our exiting, and if they have any stopped jobs,
288 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
289 */
290static void
291kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
292{
293 struct pid *pgrp = task_pgrp(tsk);
294 struct task_struct *ignored_task = tsk;
295
296 if (!parent)
297 /* exit: our father is in a different pgrp than
298 * we are and we were the only connection outside.
299 */
300 parent = tsk->real_parent;
301 else
302 /* reparent: our child is in a different pgrp than
303 * we are, and it was the only connection outside.
304 */
305 ignored_task = NULL;
306
307 if (task_pgrp(parent) != pgrp &&
308 task_session(parent) == task_session(tsk) &&
309 will_become_orphaned_pgrp(pgrp, ignored_task) &&
310 has_stopped_jobs(pgrp)) {
311 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
312 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
313 }
314}
315
316/*
317 * Let kernel threads use this to say that they allow a certain signal.
318 * Must not be used if kthread was cloned with CLONE_SIGHAND.
319 */
320int allow_signal(int sig)
321{
322 if (!valid_signal(sig) || sig < 1)
323 return -EINVAL;
324
325 spin_lock_irq(¤t->sighand->siglock);
326 /* This is only needed for daemonize()'ed kthreads */
327 sigdelset(¤t->blocked, sig);
328 /*
329 * Kernel threads handle their own signals. Let the signal code
330 * know it'll be handled, so that they don't get converted to
331 * SIGKILL or just silently dropped.
332 */
333 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
334 recalc_sigpending();
335 spin_unlock_irq(¤t->sighand->siglock);
336 return 0;
337}
338
339EXPORT_SYMBOL(allow_signal);
340
341int disallow_signal(int sig)
342{
343 if (!valid_signal(sig) || sig < 1)
344 return -EINVAL;
345
346 spin_lock_irq(¤t->sighand->siglock);
347 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
348 recalc_sigpending();
349 spin_unlock_irq(¤t->sighand->siglock);
350 return 0;
351}
352
353EXPORT_SYMBOL(disallow_signal);
354
355#ifdef CONFIG_MM_OWNER
356/*
357 * A task is exiting. If it owned this mm, find a new owner for the mm.
358 */
359void mm_update_next_owner(struct mm_struct *mm)
360{
361 struct task_struct *c, *g, *p = current;
362
363retry:
364 /*
365 * If the exiting or execing task is not the owner, it's
366 * someone else's problem.
367 */
368 if (mm->owner != p)
369 return;
370 /*
371 * The current owner is exiting/execing and there are no other
372 * candidates. Do not leave the mm pointing to a possibly
373 * freed task structure.
374 */
375 if (atomic_read(&mm->mm_users) <= 1) {
376 mm->owner = NULL;
377 return;
378 }
379
380 read_lock(&tasklist_lock);
381 /*
382 * Search in the children
383 */
384 list_for_each_entry(c, &p->children, sibling) {
385 if (c->mm == mm)
386 goto assign_new_owner;
387 }
388
389 /*
390 * Search in the siblings
391 */
392 list_for_each_entry(c, &p->real_parent->children, sibling) {
393 if (c->mm == mm)
394 goto assign_new_owner;
395 }
396
397 /*
398 * Search through everything else. We should not get
399 * here often
400 */
401 do_each_thread(g, c) {
402 if (c->mm == mm)
403 goto assign_new_owner;
404 } while_each_thread(g, c);
405
406 read_unlock(&tasklist_lock);
407 /*
408 * We found no owner yet mm_users > 1: this implies that we are
409 * most likely racing with swapoff (try_to_unuse()) or /proc or
410 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
411 */
412 mm->owner = NULL;
413 return;
414
415assign_new_owner:
416 BUG_ON(c == p);
417 get_task_struct(c);
418 /*
419 * The task_lock protects c->mm from changing.
420 * We always want mm->owner->mm == mm
421 */
422 task_lock(c);
423 /*
424 * Delay read_unlock() till we have the task_lock()
425 * to ensure that c does not slip away underneath us
426 */
427 read_unlock(&tasklist_lock);
428 if (c->mm != mm) {
429 task_unlock(c);
430 put_task_struct(c);
431 goto retry;
432 }
433 mm->owner = c;
434 task_unlock(c);
435 put_task_struct(c);
436}
437#endif /* CONFIG_MM_OWNER */
438
439/*
440 * Turn us into a lazy TLB process if we
441 * aren't already..
442 */
443static void exit_mm(struct task_struct * tsk)
444{
445 struct mm_struct *mm = tsk->mm;
446 struct core_state *core_state;
447
448 mm_release(tsk, mm);
449 if (!mm)
450 return;
451 sync_mm_rss(mm);
452 /*
453 * Serialize with any possible pending coredump.
454 * We must hold mmap_sem around checking core_state
455 * and clearing tsk->mm. The core-inducing thread
456 * will increment ->nr_threads for each thread in the
457 * group with ->mm != NULL.
458 */
459 down_read(&mm->mmap_sem);
460 core_state = mm->core_state;
461 if (core_state) {
462 struct core_thread self;
463 up_read(&mm->mmap_sem);
464
465 self.task = tsk;
466 self.next = xchg(&core_state->dumper.next, &self);
467 /*
468 * Implies mb(), the result of xchg() must be visible
469 * to core_state->dumper.
470 */
471 if (atomic_dec_and_test(&core_state->nr_threads))
472 complete(&core_state->startup);
473
474 for (;;) {
475 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
476 if (!self.task) /* see coredump_finish() */
477 break;
478 freezable_schedule();
479 }
480 __set_task_state(tsk, TASK_RUNNING);
481 down_read(&mm->mmap_sem);
482 }
483 atomic_inc(&mm->mm_count);
484 BUG_ON(mm != tsk->active_mm);
485 /* more a memory barrier than a real lock */
486 task_lock(tsk);
487 tsk->mm = NULL;
488 up_read(&mm->mmap_sem);
489 enter_lazy_tlb(mm, current);
490 task_unlock(tsk);
491 mm_update_next_owner(mm);
492 mmput(mm);
493}
494
495/*
496 * When we die, we re-parent all our children, and try to:
497 * 1. give them to another thread in our thread group, if such a member exists
498 * 2. give it to the first ancestor process which prctl'd itself as a
499 * child_subreaper for its children (like a service manager)
500 * 3. give it to the init process (PID 1) in our pid namespace
501 */
502static struct task_struct *find_new_reaper(struct task_struct *father)
503 __releases(&tasklist_lock)
504 __acquires(&tasklist_lock)
505{
506 struct pid_namespace *pid_ns = task_active_pid_ns(father);
507 struct task_struct *thread;
508
509 thread = father;
510 while_each_thread(father, thread) {
511 if (thread->flags & PF_EXITING)
512 continue;
513 if (unlikely(pid_ns->child_reaper == father))
514 pid_ns->child_reaper = thread;
515 return thread;
516 }
517
518 if (unlikely(pid_ns->child_reaper == father)) {
519 write_unlock_irq(&tasklist_lock);
520 if (unlikely(pid_ns == &init_pid_ns)) {
521 panic("Attempted to kill init! exitcode=0x%08x\n",
522 father->signal->group_exit_code ?:
523 father->exit_code);
524 }
525
526 zap_pid_ns_processes(pid_ns);
527 write_lock_irq(&tasklist_lock);
528 } else if (father->signal->has_child_subreaper) {
529 struct task_struct *reaper;
530
531 /*
532 * Find the first ancestor marked as child_subreaper.
533 * Note that the code below checks same_thread_group(reaper,
534 * pid_ns->child_reaper). This is what we need to DTRT in a
535 * PID namespace. However we still need the check above, see
536 * http://marc.info/?l=linux-kernel&m=131385460420380
537 */
538 for (reaper = father->real_parent;
539 reaper != &init_task;
540 reaper = reaper->real_parent) {
541 if (same_thread_group(reaper, pid_ns->child_reaper))
542 break;
543 if (!reaper->signal->is_child_subreaper)
544 continue;
545 thread = reaper;
546 do {
547 if (!(thread->flags & PF_EXITING))
548 return reaper;
549 } while_each_thread(reaper, thread);
550 }
551 }
552
553 return pid_ns->child_reaper;
554}
555
556/*
557* Any that need to be release_task'd are put on the @dead list.
558 */
559static void reparent_leader(struct task_struct *father, struct task_struct *p,
560 struct list_head *dead)
561{
562 list_move_tail(&p->sibling, &p->real_parent->children);
563
564 if (p->exit_state == EXIT_DEAD)
565 return;
566 /*
567 * If this is a threaded reparent there is no need to
568 * notify anyone anything has happened.
569 */
570 if (same_thread_group(p->real_parent, father))
571 return;
572
573 /* We don't want people slaying init. */
574 p->exit_signal = SIGCHLD;
575
576 /* If it has exited notify the new parent about this child's death. */
577 if (!p->ptrace &&
578 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
579 if (do_notify_parent(p, p->exit_signal)) {
580 p->exit_state = EXIT_DEAD;
581 list_move_tail(&p->sibling, dead);
582 }
583 }
584
585 kill_orphaned_pgrp(p, father);
586}
587
588static void forget_original_parent(struct task_struct *father)
589{
590 struct task_struct *p, *n, *reaper;
591 LIST_HEAD(dead_children);
592
593 write_lock_irq(&tasklist_lock);
594 /*
595 * Note that exit_ptrace() and find_new_reaper() might
596 * drop tasklist_lock and reacquire it.
597 */
598 exit_ptrace(father);
599 reaper = find_new_reaper(father);
600
601 list_for_each_entry_safe(p, n, &father->children, sibling) {
602 struct task_struct *t = p;
603 do {
604 t->real_parent = reaper;
605 if (t->parent == father) {
606 BUG_ON(t->ptrace);
607 t->parent = t->real_parent;
608 }
609 if (t->pdeath_signal)
610 group_send_sig_info(t->pdeath_signal,
611 SEND_SIG_NOINFO, t);
612 } while_each_thread(p, t);
613 reparent_leader(father, p, &dead_children);
614 }
615 write_unlock_irq(&tasklist_lock);
616
617 BUG_ON(!list_empty(&father->children));
618
619 list_for_each_entry_safe(p, n, &dead_children, sibling) {
620 list_del_init(&p->sibling);
621 release_task(p);
622 }
623}
624
625/*
626 * Send signals to all our closest relatives so that they know
627 * to properly mourn us..
628 */
629static void exit_notify(struct task_struct *tsk, int group_dead)
630{
631 bool autoreap;
632
633 /*
634 * This does two things:
635 *
636 * A. Make init inherit all the child processes
637 * B. Check to see if any process groups have become orphaned
638 * as a result of our exiting, and if they have any stopped
639 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
640 */
641 forget_original_parent(tsk);
642
643 write_lock_irq(&tasklist_lock);
644 if (group_dead)
645 kill_orphaned_pgrp(tsk->group_leader, NULL);
646
647 if (unlikely(tsk->ptrace)) {
648 int sig = thread_group_leader(tsk) &&
649 thread_group_empty(tsk) &&
650 !ptrace_reparented(tsk) ?
651 tsk->exit_signal : SIGCHLD;
652 autoreap = do_notify_parent(tsk, sig);
653 } else if (thread_group_leader(tsk)) {
654 autoreap = thread_group_empty(tsk) &&
655 do_notify_parent(tsk, tsk->exit_signal);
656 } else {
657 autoreap = true;
658 }
659
660 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
661
662 /* mt-exec, de_thread() is waiting for group leader */
663 if (unlikely(tsk->signal->notify_count < 0))
664 wake_up_process(tsk->signal->group_exit_task);
665 write_unlock_irq(&tasklist_lock);
666
667 /* If the process is dead, release it - nobody will wait for it */
668 if (autoreap)
669 release_task(tsk);
670}
671
672#ifdef CONFIG_DEBUG_STACK_USAGE
673static void check_stack_usage(void)
674{
675 static DEFINE_SPINLOCK(low_water_lock);
676 static int lowest_to_date = THREAD_SIZE;
677 unsigned long free;
678
679 free = stack_not_used(current);
680
681 if (free >= lowest_to_date)
682 return;
683
684 spin_lock(&low_water_lock);
685 if (free < lowest_to_date) {
686 printk(KERN_WARNING "%s (%d) used greatest stack depth: "
687 "%lu bytes left\n",
688 current->comm, task_pid_nr(current), free);
689 lowest_to_date = free;
690 }
691 spin_unlock(&low_water_lock);
692}
693#else
694static inline void check_stack_usage(void) {}
695#endif
696
697void do_exit(long code)
698{
699 struct task_struct *tsk = current;
700 int group_dead;
701
702 profile_task_exit(tsk);
703
704 WARN_ON(blk_needs_flush_plug(tsk));
705
706 if (unlikely(in_interrupt()))
707 panic("Aiee, killing interrupt handler!");
708 if (unlikely(!tsk->pid))
709 panic("Attempted to kill the idle task!");
710
711 /*
712 * If do_exit is called because this processes oopsed, it's possible
713 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
714 * continuing. Amongst other possible reasons, this is to prevent
715 * mm_release()->clear_child_tid() from writing to a user-controlled
716 * kernel address.
717 */
718 set_fs(USER_DS);
719
720 ptrace_event(PTRACE_EVENT_EXIT, code);
721
722 validate_creds_for_do_exit(tsk);
723
724 /*
725 * We're taking recursive faults here in do_exit. Safest is to just
726 * leave this task alone and wait for reboot.
727 */
728 if (unlikely(tsk->flags & PF_EXITING)) {
729 printk(KERN_ALERT
730 "Fixing recursive fault but reboot is needed!\n");
731 /*
732 * We can do this unlocked here. The futex code uses
733 * this flag just to verify whether the pi state
734 * cleanup has been done or not. In the worst case it
735 * loops once more. We pretend that the cleanup was
736 * done as there is no way to return. Either the
737 * OWNER_DIED bit is set by now or we push the blocked
738 * task into the wait for ever nirwana as well.
739 */
740 tsk->flags |= PF_EXITPIDONE;
741 set_current_state(TASK_UNINTERRUPTIBLE);
742 schedule();
743 }
744
745 exit_signals(tsk); /* sets PF_EXITING */
746 /*
747 * tsk->flags are checked in the futex code to protect against
748 * an exiting task cleaning up the robust pi futexes.
749 */
750 smp_mb();
751 raw_spin_unlock_wait(&tsk->pi_lock);
752
753 if (unlikely(in_atomic()))
754 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
755 current->comm, task_pid_nr(current),
756 preempt_count());
757
758 acct_update_integrals(tsk);
759 /* sync mm's RSS info before statistics gathering */
760 if (tsk->mm)
761 sync_mm_rss(tsk->mm);
762 group_dead = atomic_dec_and_test(&tsk->signal->live);
763 if (group_dead) {
764 hrtimer_cancel(&tsk->signal->real_timer);
765 exit_itimers(tsk->signal);
766 if (tsk->mm)
767 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
768 }
769 acct_collect(code, group_dead);
770 if (group_dead)
771 tty_audit_exit();
772 audit_free(tsk);
773
774 tsk->exit_code = code;
775 taskstats_exit(tsk, group_dead);
776
777 exit_mm(tsk);
778
779 if (group_dead)
780 acct_process();
781 trace_sched_process_exit(tsk);
782
783 exit_sem(tsk);
784 exit_shm(tsk);
785 exit_files(tsk);
786 exit_fs(tsk);
787 if (group_dead)
788 disassociate_ctty(1);
789 exit_task_namespaces(tsk);
790 exit_task_work(tsk);
791 exit_thread();
792
793 /*
794 * Flush inherited counters to the parent - before the parent
795 * gets woken up by child-exit notifications.
796 *
797 * because of cgroup mode, must be called before cgroup_exit()
798 */
799 perf_event_exit_task(tsk);
800
801 cgroup_exit(tsk);
802
803 module_put(task_thread_info(tsk)->exec_domain->module);
804
805 /*
806 * FIXME: do that only when needed, using sched_exit tracepoint
807 */
808 flush_ptrace_hw_breakpoint(tsk);
809
810 exit_notify(tsk, group_dead);
811 proc_exit_connector(tsk);
812#ifdef CONFIG_NUMA
813 task_lock(tsk);
814 mpol_put(tsk->mempolicy);
815 tsk->mempolicy = NULL;
816 task_unlock(tsk);
817#endif
818#ifdef CONFIG_FUTEX
819 if (unlikely(current->pi_state_cache))
820 kfree(current->pi_state_cache);
821#endif
822 /*
823 * Make sure we are holding no locks:
824 */
825 debug_check_no_locks_held();
826 /*
827 * We can do this unlocked here. The futex code uses this flag
828 * just to verify whether the pi state cleanup has been done
829 * or not. In the worst case it loops once more.
830 */
831 tsk->flags |= PF_EXITPIDONE;
832
833 if (tsk->io_context)
834 exit_io_context(tsk);
835
836 if (tsk->splice_pipe)
837 free_pipe_info(tsk->splice_pipe);
838
839 if (tsk->task_frag.page)
840 put_page(tsk->task_frag.page);
841
842 validate_creds_for_do_exit(tsk);
843
844 check_stack_usage();
845 preempt_disable();
846 if (tsk->nr_dirtied)
847 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
848 exit_rcu();
849
850 /*
851 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
852 * when the following two conditions become true.
853 * - There is race condition of mmap_sem (It is acquired by
854 * exit_mm()), and
855 * - SMI occurs before setting TASK_RUNINNG.
856 * (or hypervisor of virtual machine switches to other guest)
857 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
858 *
859 * To avoid it, we have to wait for releasing tsk->pi_lock which
860 * is held by try_to_wake_up()
861 */
862 smp_mb();
863 raw_spin_unlock_wait(&tsk->pi_lock);
864
865 /* causes final put_task_struct in finish_task_switch(). */
866 tsk->state = TASK_DEAD;
867 tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */
868 schedule();
869 BUG();
870 /* Avoid "noreturn function does return". */
871 for (;;)
872 cpu_relax(); /* For when BUG is null */
873}
874
875EXPORT_SYMBOL_GPL(do_exit);
876
877void complete_and_exit(struct completion *comp, long code)
878{
879 if (comp)
880 complete(comp);
881
882 do_exit(code);
883}
884
885EXPORT_SYMBOL(complete_and_exit);
886
887SYSCALL_DEFINE1(exit, int, error_code)
888{
889 do_exit((error_code&0xff)<<8);
890}
891
892/*
893 * Take down every thread in the group. This is called by fatal signals
894 * as well as by sys_exit_group (below).
895 */
896void
897do_group_exit(int exit_code)
898{
899 struct signal_struct *sig = current->signal;
900
901 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
902
903 if (signal_group_exit(sig))
904 exit_code = sig->group_exit_code;
905 else if (!thread_group_empty(current)) {
906 struct sighand_struct *const sighand = current->sighand;
907 spin_lock_irq(&sighand->siglock);
908 if (signal_group_exit(sig))
909 /* Another thread got here before we took the lock. */
910 exit_code = sig->group_exit_code;
911 else {
912 sig->group_exit_code = exit_code;
913 sig->flags = SIGNAL_GROUP_EXIT;
914 zap_other_threads(current);
915 }
916 spin_unlock_irq(&sighand->siglock);
917 }
918
919 do_exit(exit_code);
920 /* NOTREACHED */
921}
922
923/*
924 * this kills every thread in the thread group. Note that any externally
925 * wait4()-ing process will get the correct exit code - even if this
926 * thread is not the thread group leader.
927 */
928SYSCALL_DEFINE1(exit_group, int, error_code)
929{
930 do_group_exit((error_code & 0xff) << 8);
931 /* NOTREACHED */
932 return 0;
933}
934
935struct wait_opts {
936 enum pid_type wo_type;
937 int wo_flags;
938 struct pid *wo_pid;
939
940 struct siginfo __user *wo_info;
941 int __user *wo_stat;
942 struct rusage __user *wo_rusage;
943
944 wait_queue_t child_wait;
945 int notask_error;
946};
947
948static inline
949struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
950{
951 if (type != PIDTYPE_PID)
952 task = task->group_leader;
953 return task->pids[type].pid;
954}
955
956static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
957{
958 return wo->wo_type == PIDTYPE_MAX ||
959 task_pid_type(p, wo->wo_type) == wo->wo_pid;
960}
961
962static int eligible_child(struct wait_opts *wo, struct task_struct *p)
963{
964 if (!eligible_pid(wo, p))
965 return 0;
966 /* Wait for all children (clone and not) if __WALL is set;
967 * otherwise, wait for clone children *only* if __WCLONE is
968 * set; otherwise, wait for non-clone children *only*. (Note:
969 * A "clone" child here is one that reports to its parent
970 * using a signal other than SIGCHLD.) */
971 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
972 && !(wo->wo_flags & __WALL))
973 return 0;
974
975 return 1;
976}
977
978static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
979 pid_t pid, uid_t uid, int why, int status)
980{
981 struct siginfo __user *infop;
982 int retval = wo->wo_rusage
983 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
984
985 put_task_struct(p);
986 infop = wo->wo_info;
987 if (infop) {
988 if (!retval)
989 retval = put_user(SIGCHLD, &infop->si_signo);
990 if (!retval)
991 retval = put_user(0, &infop->si_errno);
992 if (!retval)
993 retval = put_user((short)why, &infop->si_code);
994 if (!retval)
995 retval = put_user(pid, &infop->si_pid);
996 if (!retval)
997 retval = put_user(uid, &infop->si_uid);
998 if (!retval)
999 retval = put_user(status, &infop->si_status);
1000 }
1001 if (!retval)
1002 retval = pid;
1003 return retval;
1004}
1005
1006/*
1007 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1008 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1009 * the lock and this task is uninteresting. If we return nonzero, we have
1010 * released the lock and the system call should return.
1011 */
1012static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1013{
1014 unsigned long state;
1015 int retval, status, traced;
1016 pid_t pid = task_pid_vnr(p);
1017 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
1018 struct siginfo __user *infop;
1019
1020 if (!likely(wo->wo_flags & WEXITED))
1021 return 0;
1022
1023 if (unlikely(wo->wo_flags & WNOWAIT)) {
1024 int exit_code = p->exit_code;
1025 int why;
1026
1027 get_task_struct(p);
1028 read_unlock(&tasklist_lock);
1029 if ((exit_code & 0x7f) == 0) {
1030 why = CLD_EXITED;
1031 status = exit_code >> 8;
1032 } else {
1033 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1034 status = exit_code & 0x7f;
1035 }
1036 return wait_noreap_copyout(wo, p, pid, uid, why, status);
1037 }
1038
1039 traced = ptrace_reparented(p);
1040 /*
1041 * Move the task's state to DEAD/TRACE, only one thread can do this.
1042 */
1043 state = traced && thread_group_leader(p) ? EXIT_TRACE : EXIT_DEAD;
1044 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1045 return 0;
1046 /*
1047 * It can be ptraced but not reparented, check
1048 * thread_group_leader() to filter out sub-threads.
1049 */
1050 if (likely(!traced) && thread_group_leader(p)) {
1051 struct signal_struct *psig;
1052 struct signal_struct *sig;
1053 unsigned long maxrss;
1054 cputime_t tgutime, tgstime;
1055
1056 /*
1057 * The resource counters for the group leader are in its
1058 * own task_struct. Those for dead threads in the group
1059 * are in its signal_struct, as are those for the child
1060 * processes it has previously reaped. All these
1061 * accumulate in the parent's signal_struct c* fields.
1062 *
1063 * We don't bother to take a lock here to protect these
1064 * p->signal fields, because they are only touched by
1065 * __exit_signal, which runs with tasklist_lock
1066 * write-locked anyway, and so is excluded here. We do
1067 * need to protect the access to parent->signal fields,
1068 * as other threads in the parent group can be right
1069 * here reaping other children at the same time.
1070 *
1071 * We use thread_group_cputime_adjusted() to get times for the thread
1072 * group, which consolidates times for all threads in the
1073 * group including the group leader.
1074 */
1075 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1076 spin_lock_irq(&p->real_parent->sighand->siglock);
1077 psig = p->real_parent->signal;
1078 sig = p->signal;
1079 psig->cutime += tgutime + sig->cutime;
1080 psig->cstime += tgstime + sig->cstime;
1081 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1082 psig->cmin_flt +=
1083 p->min_flt + sig->min_flt + sig->cmin_flt;
1084 psig->cmaj_flt +=
1085 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1086 psig->cnvcsw +=
1087 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1088 psig->cnivcsw +=
1089 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1090 psig->cinblock +=
1091 task_io_get_inblock(p) +
1092 sig->inblock + sig->cinblock;
1093 psig->coublock +=
1094 task_io_get_oublock(p) +
1095 sig->oublock + sig->coublock;
1096 maxrss = max(sig->maxrss, sig->cmaxrss);
1097 if (psig->cmaxrss < maxrss)
1098 psig->cmaxrss = maxrss;
1099 task_io_accounting_add(&psig->ioac, &p->ioac);
1100 task_io_accounting_add(&psig->ioac, &sig->ioac);
1101 spin_unlock_irq(&p->real_parent->sighand->siglock);
1102 }
1103
1104 /*
1105 * Now we are sure this task is interesting, and no other
1106 * thread can reap it because we its state == DEAD/TRACE.
1107 */
1108 read_unlock(&tasklist_lock);
1109
1110 retval = wo->wo_rusage
1111 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1112 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1113 ? p->signal->group_exit_code : p->exit_code;
1114 if (!retval && wo->wo_stat)
1115 retval = put_user(status, wo->wo_stat);
1116
1117 infop = wo->wo_info;
1118 if (!retval && infop)
1119 retval = put_user(SIGCHLD, &infop->si_signo);
1120 if (!retval && infop)
1121 retval = put_user(0, &infop->si_errno);
1122 if (!retval && infop) {
1123 int why;
1124
1125 if ((status & 0x7f) == 0) {
1126 why = CLD_EXITED;
1127 status >>= 8;
1128 } else {
1129 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1130 status &= 0x7f;
1131 }
1132 retval = put_user((short)why, &infop->si_code);
1133 if (!retval)
1134 retval = put_user(status, &infop->si_status);
1135 }
1136 if (!retval && infop)
1137 retval = put_user(pid, &infop->si_pid);
1138 if (!retval && infop)
1139 retval = put_user(uid, &infop->si_uid);
1140 if (!retval)
1141 retval = pid;
1142
1143 if (state == EXIT_TRACE) {
1144 write_lock_irq(&tasklist_lock);
1145 /* We dropped tasklist, ptracer could die and untrace */
1146 ptrace_unlink(p);
1147
1148 /* If parent wants a zombie, don't release it now */
1149 state = EXIT_ZOMBIE;
1150 if (do_notify_parent(p, p->exit_signal))
1151 state = EXIT_DEAD;
1152 p->exit_state = state;
1153 write_unlock_irq(&tasklist_lock);
1154 }
1155 if (state == EXIT_DEAD)
1156 release_task(p);
1157
1158 return retval;
1159}
1160
1161static int *task_stopped_code(struct task_struct *p, bool ptrace)
1162{
1163 if (ptrace) {
1164 if (task_is_stopped_or_traced(p) &&
1165 !(p->jobctl & JOBCTL_LISTENING))
1166 return &p->exit_code;
1167 } else {
1168 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1169 return &p->signal->group_exit_code;
1170 }
1171 return NULL;
1172}
1173
1174/**
1175 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1176 * @wo: wait options
1177 * @ptrace: is the wait for ptrace
1178 * @p: task to wait for
1179 *
1180 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1181 *
1182 * CONTEXT:
1183 * read_lock(&tasklist_lock), which is released if return value is
1184 * non-zero. Also, grabs and releases @p->sighand->siglock.
1185 *
1186 * RETURNS:
1187 * 0 if wait condition didn't exist and search for other wait conditions
1188 * should continue. Non-zero return, -errno on failure and @p's pid on
1189 * success, implies that tasklist_lock is released and wait condition
1190 * search should terminate.
1191 */
1192static int wait_task_stopped(struct wait_opts *wo,
1193 int ptrace, struct task_struct *p)
1194{
1195 struct siginfo __user *infop;
1196 int retval, exit_code, *p_code, why;
1197 uid_t uid = 0; /* unneeded, required by compiler */
1198 pid_t pid;
1199
1200 /*
1201 * Traditionally we see ptrace'd stopped tasks regardless of options.
1202 */
1203 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1204 return 0;
1205
1206 if (!task_stopped_code(p, ptrace))
1207 return 0;
1208
1209 exit_code = 0;
1210 spin_lock_irq(&p->sighand->siglock);
1211
1212 p_code = task_stopped_code(p, ptrace);
1213 if (unlikely(!p_code))
1214 goto unlock_sig;
1215
1216 exit_code = *p_code;
1217 if (!exit_code)
1218 goto unlock_sig;
1219
1220 if (!unlikely(wo->wo_flags & WNOWAIT))
1221 *p_code = 0;
1222
1223 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1224unlock_sig:
1225 spin_unlock_irq(&p->sighand->siglock);
1226 if (!exit_code)
1227 return 0;
1228
1229 /*
1230 * Now we are pretty sure this task is interesting.
1231 * Make sure it doesn't get reaped out from under us while we
1232 * give up the lock and then examine it below. We don't want to
1233 * keep holding onto the tasklist_lock while we call getrusage and
1234 * possibly take page faults for user memory.
1235 */
1236 get_task_struct(p);
1237 pid = task_pid_vnr(p);
1238 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1239 read_unlock(&tasklist_lock);
1240
1241 if (unlikely(wo->wo_flags & WNOWAIT))
1242 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
1243
1244 retval = wo->wo_rusage
1245 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1246 if (!retval && wo->wo_stat)
1247 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
1248
1249 infop = wo->wo_info;
1250 if (!retval && infop)
1251 retval = put_user(SIGCHLD, &infop->si_signo);
1252 if (!retval && infop)
1253 retval = put_user(0, &infop->si_errno);
1254 if (!retval && infop)
1255 retval = put_user((short)why, &infop->si_code);
1256 if (!retval && infop)
1257 retval = put_user(exit_code, &infop->si_status);
1258 if (!retval && infop)
1259 retval = put_user(pid, &infop->si_pid);
1260 if (!retval && infop)
1261 retval = put_user(uid, &infop->si_uid);
1262 if (!retval)
1263 retval = pid;
1264 put_task_struct(p);
1265
1266 BUG_ON(!retval);
1267 return retval;
1268}
1269
1270/*
1271 * Handle do_wait work for one task in a live, non-stopped state.
1272 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1273 * the lock and this task is uninteresting. If we return nonzero, we have
1274 * released the lock and the system call should return.
1275 */
1276static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1277{
1278 int retval;
1279 pid_t pid;
1280 uid_t uid;
1281
1282 if (!unlikely(wo->wo_flags & WCONTINUED))
1283 return 0;
1284
1285 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1286 return 0;
1287
1288 spin_lock_irq(&p->sighand->siglock);
1289 /* Re-check with the lock held. */
1290 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1291 spin_unlock_irq(&p->sighand->siglock);
1292 return 0;
1293 }
1294 if (!unlikely(wo->wo_flags & WNOWAIT))
1295 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1296 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1297 spin_unlock_irq(&p->sighand->siglock);
1298
1299 pid = task_pid_vnr(p);
1300 get_task_struct(p);
1301 read_unlock(&tasklist_lock);
1302
1303 if (!wo->wo_info) {
1304 retval = wo->wo_rusage
1305 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1306 put_task_struct(p);
1307 if (!retval && wo->wo_stat)
1308 retval = put_user(0xffff, wo->wo_stat);
1309 if (!retval)
1310 retval = pid;
1311 } else {
1312 retval = wait_noreap_copyout(wo, p, pid, uid,
1313 CLD_CONTINUED, SIGCONT);
1314 BUG_ON(retval == 0);
1315 }
1316
1317 return retval;
1318}
1319
1320/*
1321 * Consider @p for a wait by @parent.
1322 *
1323 * -ECHILD should be in ->notask_error before the first call.
1324 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1325 * Returns zero if the search for a child should continue;
1326 * then ->notask_error is 0 if @p is an eligible child,
1327 * or another error from security_task_wait(), or still -ECHILD.
1328 */
1329static int wait_consider_task(struct wait_opts *wo, int ptrace,
1330 struct task_struct *p)
1331{
1332 int ret;
1333
1334 if (unlikely(p->exit_state == EXIT_DEAD))
1335 return 0;
1336
1337 ret = eligible_child(wo, p);
1338 if (!ret)
1339 return ret;
1340
1341 ret = security_task_wait(p);
1342 if (unlikely(ret < 0)) {
1343 /*
1344 * If we have not yet seen any eligible child,
1345 * then let this error code replace -ECHILD.
1346 * A permission error will give the user a clue
1347 * to look for security policy problems, rather
1348 * than for mysterious wait bugs.
1349 */
1350 if (wo->notask_error)
1351 wo->notask_error = ret;
1352 return 0;
1353 }
1354
1355 if (unlikely(p->exit_state == EXIT_TRACE)) {
1356 /*
1357 * ptrace == 0 means we are the natural parent. In this case
1358 * we should clear notask_error, debugger will notify us.
1359 */
1360 if (likely(!ptrace))
1361 wo->notask_error = 0;
1362 return 0;
1363 }
1364
1365 if (likely(!ptrace) && unlikely(p->ptrace)) {
1366 /*
1367 * If it is traced by its real parent's group, just pretend
1368 * the caller is ptrace_do_wait() and reap this child if it
1369 * is zombie.
1370 *
1371 * This also hides group stop state from real parent; otherwise
1372 * a single stop can be reported twice as group and ptrace stop.
1373 * If a ptracer wants to distinguish these two events for its
1374 * own children it should create a separate process which takes
1375 * the role of real parent.
1376 */
1377 if (!ptrace_reparented(p))
1378 ptrace = 1;
1379 }
1380
1381 /* slay zombie? */
1382 if (p->exit_state == EXIT_ZOMBIE) {
1383 /* we don't reap group leaders with subthreads */
1384 if (!delay_group_leader(p)) {
1385 /*
1386 * A zombie ptracee is only visible to its ptracer.
1387 * Notification and reaping will be cascaded to the
1388 * real parent when the ptracer detaches.
1389 */
1390 if (unlikely(ptrace) || likely(!p->ptrace))
1391 return wait_task_zombie(wo, p);
1392 }
1393
1394 /*
1395 * Allow access to stopped/continued state via zombie by
1396 * falling through. Clearing of notask_error is complex.
1397 *
1398 * When !@ptrace:
1399 *
1400 * If WEXITED is set, notask_error should naturally be
1401 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1402 * so, if there are live subthreads, there are events to
1403 * wait for. If all subthreads are dead, it's still safe
1404 * to clear - this function will be called again in finite
1405 * amount time once all the subthreads are released and
1406 * will then return without clearing.
1407 *
1408 * When @ptrace:
1409 *
1410 * Stopped state is per-task and thus can't change once the
1411 * target task dies. Only continued and exited can happen.
1412 * Clear notask_error if WCONTINUED | WEXITED.
1413 */
1414 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1415 wo->notask_error = 0;
1416 } else {
1417 /*
1418 * @p is alive and it's gonna stop, continue or exit, so
1419 * there always is something to wait for.
1420 */
1421 wo->notask_error = 0;
1422 }
1423
1424 /*
1425 * Wait for stopped. Depending on @ptrace, different stopped state
1426 * is used and the two don't interact with each other.
1427 */
1428 ret = wait_task_stopped(wo, ptrace, p);
1429 if (ret)
1430 return ret;
1431
1432 /*
1433 * Wait for continued. There's only one continued state and the
1434 * ptracer can consume it which can confuse the real parent. Don't
1435 * use WCONTINUED from ptracer. You don't need or want it.
1436 */
1437 return wait_task_continued(wo, p);
1438}
1439
1440/*
1441 * Do the work of do_wait() for one thread in the group, @tsk.
1442 *
1443 * -ECHILD should be in ->notask_error before the first call.
1444 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1445 * Returns zero if the search for a child should continue; then
1446 * ->notask_error is 0 if there were any eligible children,
1447 * or another error from security_task_wait(), or still -ECHILD.
1448 */
1449static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1450{
1451 struct task_struct *p;
1452
1453 list_for_each_entry(p, &tsk->children, sibling) {
1454 int ret = wait_consider_task(wo, 0, p);
1455 if (ret)
1456 return ret;
1457 }
1458
1459 return 0;
1460}
1461
1462static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1463{
1464 struct task_struct *p;
1465
1466 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1467 int ret = wait_consider_task(wo, 1, p);
1468 if (ret)
1469 return ret;
1470 }
1471
1472 return 0;
1473}
1474
1475static int child_wait_callback(wait_queue_t *wait, unsigned mode,
1476 int sync, void *key)
1477{
1478 struct wait_opts *wo = container_of(wait, struct wait_opts,
1479 child_wait);
1480 struct task_struct *p = key;
1481
1482 if (!eligible_pid(wo, p))
1483 return 0;
1484
1485 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1486 return 0;
1487
1488 return default_wake_function(wait, mode, sync, key);
1489}
1490
1491void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1492{
1493 __wake_up_sync_key(&parent->signal->wait_chldexit,
1494 TASK_INTERRUPTIBLE, 1, p);
1495}
1496
1497static long do_wait(struct wait_opts *wo)
1498{
1499 struct task_struct *tsk;
1500 int retval;
1501
1502 trace_sched_process_wait(wo->wo_pid);
1503
1504 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1505 wo->child_wait.private = current;
1506 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1507repeat:
1508 /*
1509 * If there is nothing that can match our critiera just get out.
1510 * We will clear ->notask_error to zero if we see any child that
1511 * might later match our criteria, even if we are not able to reap
1512 * it yet.
1513 */
1514 wo->notask_error = -ECHILD;
1515 if ((wo->wo_type < PIDTYPE_MAX) &&
1516 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1517 goto notask;
1518
1519 set_current_state(TASK_INTERRUPTIBLE);
1520 read_lock(&tasklist_lock);
1521 tsk = current;
1522 do {
1523 retval = do_wait_thread(wo, tsk);
1524 if (retval)
1525 goto end;
1526
1527 retval = ptrace_do_wait(wo, tsk);
1528 if (retval)
1529 goto end;
1530
1531 if (wo->wo_flags & __WNOTHREAD)
1532 break;
1533 } while_each_thread(current, tsk);
1534 read_unlock(&tasklist_lock);
1535
1536notask:
1537 retval = wo->notask_error;
1538 if (!retval && !(wo->wo_flags & WNOHANG)) {
1539 retval = -ERESTARTSYS;
1540 if (!signal_pending(current)) {
1541 schedule();
1542 goto repeat;
1543 }
1544 }
1545end:
1546 __set_current_state(TASK_RUNNING);
1547 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1548 return retval;
1549}
1550
1551SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1552 infop, int, options, struct rusage __user *, ru)
1553{
1554 struct wait_opts wo;
1555 struct pid *pid = NULL;
1556 enum pid_type type;
1557 long ret;
1558
1559 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1560 return -EINVAL;
1561 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1562 return -EINVAL;
1563
1564 switch (which) {
1565 case P_ALL:
1566 type = PIDTYPE_MAX;
1567 break;
1568 case P_PID:
1569 type = PIDTYPE_PID;
1570 if (upid <= 0)
1571 return -EINVAL;
1572 break;
1573 case P_PGID:
1574 type = PIDTYPE_PGID;
1575 if (upid <= 0)
1576 return -EINVAL;
1577 break;
1578 default:
1579 return -EINVAL;
1580 }
1581
1582 if (type < PIDTYPE_MAX)
1583 pid = find_get_pid(upid);
1584
1585 wo.wo_type = type;
1586 wo.wo_pid = pid;
1587 wo.wo_flags = options;
1588 wo.wo_info = infop;
1589 wo.wo_stat = NULL;
1590 wo.wo_rusage = ru;
1591 ret = do_wait(&wo);
1592
1593 if (ret > 0) {
1594 ret = 0;
1595 } else if (infop) {
1596 /*
1597 * For a WNOHANG return, clear out all the fields
1598 * we would set so the user can easily tell the
1599 * difference.
1600 */
1601 if (!ret)
1602 ret = put_user(0, &infop->si_signo);
1603 if (!ret)
1604 ret = put_user(0, &infop->si_errno);
1605 if (!ret)
1606 ret = put_user(0, &infop->si_code);
1607 if (!ret)
1608 ret = put_user(0, &infop->si_pid);
1609 if (!ret)
1610 ret = put_user(0, &infop->si_uid);
1611 if (!ret)
1612 ret = put_user(0, &infop->si_status);
1613 }
1614
1615 put_pid(pid);
1616 return ret;
1617}
1618
1619SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1620 int, options, struct rusage __user *, ru)
1621{
1622 struct wait_opts wo;
1623 struct pid *pid = NULL;
1624 enum pid_type type;
1625 long ret;
1626
1627 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1628 __WNOTHREAD|__WCLONE|__WALL))
1629 return -EINVAL;
1630
1631 if (upid == -1)
1632 type = PIDTYPE_MAX;
1633 else if (upid < 0) {
1634 type = PIDTYPE_PGID;
1635 pid = find_get_pid(-upid);
1636 } else if (upid == 0) {
1637 type = PIDTYPE_PGID;
1638 pid = get_task_pid(current, PIDTYPE_PGID);
1639 } else /* upid > 0 */ {
1640 type = PIDTYPE_PID;
1641 pid = find_get_pid(upid);
1642 }
1643
1644 wo.wo_type = type;
1645 wo.wo_pid = pid;
1646 wo.wo_flags = options | WEXITED;
1647 wo.wo_info = NULL;
1648 wo.wo_stat = stat_addr;
1649 wo.wo_rusage = ru;
1650 ret = do_wait(&wo);
1651 put_pid(pid);
1652
1653 return ret;
1654}
1655
1656#ifdef __ARCH_WANT_SYS_WAITPID
1657
1658/*
1659 * sys_waitpid() remains for compatibility. waitpid() should be
1660 * implemented by calling sys_wait4() from libc.a.
1661 */
1662SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1663{
1664 return sys_wait4(pid, stat_addr, options, NULL);
1665}
1666
1667#endif
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