]>
git.proxmox.com Git - mirror_ubuntu-artful-kernel.git/blob - kernel/exit.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
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/mnt_namespace.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/binfmts.h>
23 #include <linux/nsproxy.h>
24 #include <linux/pid_namespace.h>
25 #include <linux/ptrace.h>
26 #include <linux/profile.h>
27 #include <linux/mount.h>
28 #include <linux/proc_fs.h>
29 #include <linux/kthread.h>
30 #include <linux/mempolicy.h>
31 #include <linux/taskstats_kern.h>
32 #include <linux/delayacct.h>
33 #include <linux/freezer.h>
34 #include <linux/cgroup.h>
35 #include <linux/syscalls.h>
36 #include <linux/signal.h>
37 #include <linux/posix-timers.h>
38 #include <linux/cn_proc.h>
39 #include <linux/mutex.h>
40 #include <linux/futex.h>
41 #include <linux/compat.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>
48 #include <asm/uaccess.h>
49 #include <asm/unistd.h>
50 #include <asm/pgtable.h>
51 #include <asm/mmu_context.h>
53 static void exit_mm(struct task_struct
* tsk
);
55 static void __unhash_process(struct task_struct
*p
)
58 detach_pid(p
, PIDTYPE_PID
);
59 if (thread_group_leader(p
)) {
60 detach_pid(p
, PIDTYPE_PGID
);
61 detach_pid(p
, PIDTYPE_SID
);
63 list_del_rcu(&p
->tasks
);
64 __get_cpu_var(process_counts
)--;
66 list_del_rcu(&p
->thread_group
);
71 * This function expects the tasklist_lock write-locked.
73 static void __exit_signal(struct task_struct
*tsk
)
75 struct signal_struct
*sig
= tsk
->signal
;
76 struct sighand_struct
*sighand
;
79 BUG_ON(!atomic_read(&sig
->count
));
82 sighand
= rcu_dereference(tsk
->sighand
);
83 spin_lock(&sighand
->siglock
);
85 posix_cpu_timers_exit(tsk
);
86 if (atomic_dec_and_test(&sig
->count
))
87 posix_cpu_timers_exit_group(tsk
);
90 * If there is any task waiting for the group exit
93 if (sig
->group_exit_task
&& atomic_read(&sig
->count
) == sig
->notify_count
)
94 wake_up_process(sig
->group_exit_task
);
96 if (tsk
== sig
->curr_target
)
97 sig
->curr_target
= next_thread(tsk
);
99 * Accumulate here the counters for all threads but the
100 * group leader as they die, so they can be added into
101 * the process-wide totals when those are taken.
102 * The group leader stays around as a zombie as long
103 * as there are other threads. When it gets reaped,
104 * the exit.c code will add its counts into these totals.
105 * We won't ever get here for the group leader, since it
106 * will have been the last reference on the signal_struct.
108 sig
->utime
= cputime_add(sig
->utime
, tsk
->utime
);
109 sig
->stime
= cputime_add(sig
->stime
, tsk
->stime
);
110 sig
->gtime
= cputime_add(sig
->gtime
, tsk
->gtime
);
111 sig
->min_flt
+= tsk
->min_flt
;
112 sig
->maj_flt
+= tsk
->maj_flt
;
113 sig
->nvcsw
+= tsk
->nvcsw
;
114 sig
->nivcsw
+= tsk
->nivcsw
;
115 sig
->inblock
+= task_io_get_inblock(tsk
);
116 sig
->oublock
+= task_io_get_oublock(tsk
);
117 sig
->sum_sched_runtime
+= tsk
->se
.sum_exec_runtime
;
118 sig
= NULL
; /* Marker for below. */
121 __unhash_process(tsk
);
125 spin_unlock(&sighand
->siglock
);
128 __cleanup_sighand(sighand
);
129 clear_tsk_thread_flag(tsk
,TIF_SIGPENDING
);
130 flush_sigqueue(&tsk
->pending
);
132 flush_sigqueue(&sig
->shared_pending
);
133 taskstats_tgid_free(sig
);
134 __cleanup_signal(sig
);
138 static void delayed_put_task_struct(struct rcu_head
*rhp
)
140 put_task_struct(container_of(rhp
, struct task_struct
, rcu
));
143 void release_task(struct task_struct
* p
)
145 struct task_struct
*leader
;
148 atomic_dec(&p
->user
->processes
);
150 write_lock_irq(&tasklist_lock
);
152 BUG_ON(!list_empty(&p
->ptrace_list
) || !list_empty(&p
->ptrace_children
));
156 * If we are the last non-leader member of the thread
157 * group, and the leader is zombie, then notify the
158 * group leader's parent process. (if it wants notification.)
161 leader
= p
->group_leader
;
162 if (leader
!= p
&& thread_group_empty(leader
) && leader
->exit_state
== EXIT_ZOMBIE
) {
163 BUG_ON(leader
->exit_signal
== -1);
164 do_notify_parent(leader
, leader
->exit_signal
);
166 * If we were the last child thread and the leader has
167 * exited already, and the leader's parent ignores SIGCHLD,
168 * then we are the one who should release the leader.
170 * do_notify_parent() will have marked it self-reaping in
173 zap_leader
= (leader
->exit_signal
== -1);
176 write_unlock_irq(&tasklist_lock
);
178 call_rcu(&p
->rcu
, delayed_put_task_struct
);
181 if (unlikely(zap_leader
))
186 * This checks not only the pgrp, but falls back on the pid if no
187 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
190 * The caller must hold rcu lock or the tasklist lock.
192 struct pid
*session_of_pgrp(struct pid
*pgrp
)
194 struct task_struct
*p
;
195 struct pid
*sid
= NULL
;
197 p
= pid_task(pgrp
, PIDTYPE_PGID
);
199 p
= pid_task(pgrp
, PIDTYPE_PID
);
201 sid
= task_session(p
);
207 * Determine if a process group is "orphaned", according to the POSIX
208 * definition in 2.2.2.52. Orphaned process groups are not to be affected
209 * by terminal-generated stop signals. Newly orphaned process groups are
210 * to receive a SIGHUP and a SIGCONT.
212 * "I ask you, have you ever known what it is to be an orphan?"
214 static int will_become_orphaned_pgrp(struct pid
*pgrp
, struct task_struct
*ignored_task
)
216 struct task_struct
*p
;
219 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
220 if (p
== ignored_task
222 || is_global_init(p
->real_parent
))
224 if (task_pgrp(p
->real_parent
) != pgrp
&&
225 task_session(p
->real_parent
) == task_session(p
)) {
229 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
230 return ret
; /* (sighing) "Often!" */
233 int is_current_pgrp_orphaned(void)
237 read_lock(&tasklist_lock
);
238 retval
= will_become_orphaned_pgrp(task_pgrp(current
), NULL
);
239 read_unlock(&tasklist_lock
);
244 static int has_stopped_jobs(struct pid
*pgrp
)
247 struct task_struct
*p
;
249 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
250 if (!task_is_stopped(p
))
254 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
259 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
261 * If a kernel thread is launched as a result of a system call, or if
262 * it ever exits, it should generally reparent itself to kthreadd so it
263 * isn't in the way of other processes and is correctly cleaned up on exit.
265 * The various task state such as scheduling policy and priority may have
266 * been inherited from a user process, so we reset them to sane values here.
268 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
270 static void reparent_to_kthreadd(void)
272 write_lock_irq(&tasklist_lock
);
274 ptrace_unlink(current
);
275 /* Reparent to init */
276 remove_parent(current
);
277 current
->real_parent
= current
->parent
= kthreadd_task
;
280 /* Set the exit signal to SIGCHLD so we signal init on exit */
281 current
->exit_signal
= SIGCHLD
;
283 if (task_nice(current
) < 0)
284 set_user_nice(current
, 0);
288 security_task_reparent_to_init(current
);
289 memcpy(current
->signal
->rlim
, init_task
.signal
->rlim
,
290 sizeof(current
->signal
->rlim
));
291 atomic_inc(&(INIT_USER
->__count
));
292 write_unlock_irq(&tasklist_lock
);
293 switch_uid(INIT_USER
);
296 void __set_special_pids(struct pid
*pid
)
298 struct task_struct
*curr
= current
->group_leader
;
299 pid_t nr
= pid_nr(pid
);
301 if (task_session(curr
) != pid
) {
302 detach_pid(curr
, PIDTYPE_SID
);
303 attach_pid(curr
, PIDTYPE_SID
, pid
);
304 set_task_session(curr
, nr
);
306 if (task_pgrp(curr
) != pid
) {
307 detach_pid(curr
, PIDTYPE_PGID
);
308 attach_pid(curr
, PIDTYPE_PGID
, pid
);
309 set_task_pgrp(curr
, nr
);
313 static void set_special_pids(struct pid
*pid
)
315 write_lock_irq(&tasklist_lock
);
316 __set_special_pids(pid
);
317 write_unlock_irq(&tasklist_lock
);
321 * Let kernel threads use this to say that they
322 * allow a certain signal (since daemonize() will
323 * have disabled all of them by default).
325 int allow_signal(int sig
)
327 if (!valid_signal(sig
) || sig
< 1)
330 spin_lock_irq(¤t
->sighand
->siglock
);
331 sigdelset(¤t
->blocked
, sig
);
333 /* Kernel threads handle their own signals.
334 Let the signal code know it'll be handled, so
335 that they don't get converted to SIGKILL or
336 just silently dropped */
337 current
->sighand
->action
[(sig
)-1].sa
.sa_handler
= (void __user
*)2;
340 spin_unlock_irq(¤t
->sighand
->siglock
);
344 EXPORT_SYMBOL(allow_signal
);
346 int disallow_signal(int sig
)
348 if (!valid_signal(sig
) || sig
< 1)
351 spin_lock_irq(¤t
->sighand
->siglock
);
352 current
->sighand
->action
[(sig
)-1].sa
.sa_handler
= SIG_IGN
;
354 spin_unlock_irq(¤t
->sighand
->siglock
);
358 EXPORT_SYMBOL(disallow_signal
);
361 * Put all the gunge required to become a kernel thread without
362 * attached user resources in one place where it belongs.
365 void daemonize(const char *name
, ...)
368 struct fs_struct
*fs
;
371 va_start(args
, name
);
372 vsnprintf(current
->comm
, sizeof(current
->comm
), name
, args
);
376 * If we were started as result of loading a module, close all of the
377 * user space pages. We don't need them, and if we didn't close them
378 * they would be locked into memory.
382 * We don't want to have TIF_FREEZE set if the system-wide hibernation
383 * or suspend transition begins right now.
385 current
->flags
|= PF_NOFREEZE
;
387 if (current
->nsproxy
!= &init_nsproxy
) {
388 get_nsproxy(&init_nsproxy
);
389 switch_task_namespaces(current
, &init_nsproxy
);
391 set_special_pids(&init_struct_pid
);
392 proc_clear_tty(current
);
394 /* Block and flush all signals */
395 sigfillset(&blocked
);
396 sigprocmask(SIG_BLOCK
, &blocked
, NULL
);
397 flush_signals(current
);
399 /* Become as one with the init task */
401 exit_fs(current
); /* current->fs->count--; */
404 atomic_inc(&fs
->count
);
407 current
->files
= init_task
.files
;
408 atomic_inc(¤t
->files
->count
);
410 reparent_to_kthreadd();
413 EXPORT_SYMBOL(daemonize
);
415 static void close_files(struct files_struct
* files
)
423 * It is safe to dereference the fd table without RCU or
424 * ->file_lock because this is the last reference to the
427 fdt
= files_fdtable(files
);
431 if (i
>= fdt
->max_fds
)
433 set
= fdt
->open_fds
->fds_bits
[j
++];
436 struct file
* file
= xchg(&fdt
->fd
[i
], NULL
);
438 filp_close(file
, files
);
448 struct files_struct
*get_files_struct(struct task_struct
*task
)
450 struct files_struct
*files
;
455 atomic_inc(&files
->count
);
461 void put_files_struct(struct files_struct
*files
)
465 if (atomic_dec_and_test(&files
->count
)) {
468 * Free the fd and fdset arrays if we expanded them.
469 * If the fdtable was embedded, pass files for freeing
470 * at the end of the RCU grace period. Otherwise,
471 * you can free files immediately.
473 fdt
= files_fdtable(files
);
474 if (fdt
!= &files
->fdtab
)
475 kmem_cache_free(files_cachep
, files
);
480 EXPORT_SYMBOL(put_files_struct
);
482 void reset_files_struct(struct task_struct
*tsk
, struct files_struct
*files
)
484 struct files_struct
*old
;
490 put_files_struct(old
);
492 EXPORT_SYMBOL(reset_files_struct
);
494 static void __exit_files(struct task_struct
*tsk
)
496 struct files_struct
* files
= tsk
->files
;
502 put_files_struct(files
);
506 void exit_files(struct task_struct
*tsk
)
511 static void __put_fs_struct(struct fs_struct
*fs
)
513 /* No need to hold fs->lock if we are killing it */
514 if (atomic_dec_and_test(&fs
->count
)) {
521 mntput(fs
->altrootmnt
);
523 kmem_cache_free(fs_cachep
, fs
);
527 void put_fs_struct(struct fs_struct
*fs
)
532 static void __exit_fs(struct task_struct
*tsk
)
534 struct fs_struct
* fs
= tsk
->fs
;
544 void exit_fs(struct task_struct
*tsk
)
549 EXPORT_SYMBOL_GPL(exit_fs
);
552 * Turn us into a lazy TLB process if we
555 static void exit_mm(struct task_struct
* tsk
)
557 struct mm_struct
*mm
= tsk
->mm
;
563 * Serialize with any possible pending coredump.
564 * We must hold mmap_sem around checking core_waiters
565 * and clearing tsk->mm. The core-inducing thread
566 * will increment core_waiters for each thread in the
567 * group with ->mm != NULL.
569 down_read(&mm
->mmap_sem
);
570 if (mm
->core_waiters
) {
571 up_read(&mm
->mmap_sem
);
572 down_write(&mm
->mmap_sem
);
573 if (!--mm
->core_waiters
)
574 complete(mm
->core_startup_done
);
575 up_write(&mm
->mmap_sem
);
577 wait_for_completion(&mm
->core_done
);
578 down_read(&mm
->mmap_sem
);
580 atomic_inc(&mm
->mm_count
);
581 BUG_ON(mm
!= tsk
->active_mm
);
582 /* more a memory barrier than a real lock */
585 up_read(&mm
->mmap_sem
);
586 enter_lazy_tlb(mm
, current
);
587 /* We don't want this task to be frozen prematurely */
588 clear_freeze_flag(tsk
);
594 reparent_thread(struct task_struct
*p
, struct task_struct
*father
, int traced
)
596 if (p
->pdeath_signal
)
597 /* We already hold the tasklist_lock here. */
598 group_send_sig_info(p
->pdeath_signal
, SEND_SIG_NOINFO
, p
);
600 /* Move the child from its dying parent to the new one. */
601 if (unlikely(traced
)) {
602 /* Preserve ptrace links if someone else is tracing this child. */
603 list_del_init(&p
->ptrace_list
);
604 if (p
->parent
!= p
->real_parent
)
605 list_add(&p
->ptrace_list
, &p
->real_parent
->ptrace_children
);
607 /* If this child is being traced, then we're the one tracing it
608 * anyway, so let go of it.
612 p
->parent
= p
->real_parent
;
615 if (task_is_traced(p
)) {
617 * If it was at a trace stop, turn it into
618 * a normal stop since it's no longer being
625 /* If this is a threaded reparent there is no need to
626 * notify anyone anything has happened.
628 if (p
->real_parent
->group_leader
== father
->group_leader
)
631 /* We don't want people slaying init. */
632 if (p
->exit_signal
!= -1)
633 p
->exit_signal
= SIGCHLD
;
635 /* If we'd notified the old parent about this child's death,
636 * also notify the new parent.
638 if (!traced
&& p
->exit_state
== EXIT_ZOMBIE
&&
639 p
->exit_signal
!= -1 && thread_group_empty(p
))
640 do_notify_parent(p
, p
->exit_signal
);
643 * process group orphan check
644 * Case ii: Our child is in a different pgrp
645 * than we are, and it was the only connection
646 * outside, so the child pgrp is now orphaned.
648 if ((task_pgrp(p
) != task_pgrp(father
)) &&
649 (task_session(p
) == task_session(father
))) {
650 struct pid
*pgrp
= task_pgrp(p
);
652 if (will_become_orphaned_pgrp(pgrp
, NULL
) &&
653 has_stopped_jobs(pgrp
)) {
654 __kill_pgrp_info(SIGHUP
, SEND_SIG_PRIV
, pgrp
);
655 __kill_pgrp_info(SIGCONT
, SEND_SIG_PRIV
, pgrp
);
661 * When we die, we re-parent all our children.
662 * Try to give them to another thread in our thread
663 * group, and if no such member exists, give it to
664 * the child reaper process (ie "init") in our pid
667 static void forget_original_parent(struct task_struct
*father
)
669 struct task_struct
*p
, *n
, *reaper
= father
;
670 struct list_head ptrace_dead
;
672 INIT_LIST_HEAD(&ptrace_dead
);
674 write_lock_irq(&tasklist_lock
);
677 reaper
= next_thread(reaper
);
678 if (reaper
== father
) {
679 reaper
= task_child_reaper(father
);
682 } while (reaper
->flags
& PF_EXITING
);
685 * There are only two places where our children can be:
687 * - in our child list
688 * - in our ptraced child list
690 * Search them and reparent children.
692 list_for_each_entry_safe(p
, n
, &father
->children
, sibling
) {
697 /* if father isn't the real parent, then ptrace must be enabled */
698 BUG_ON(father
!= p
->real_parent
&& !ptrace
);
700 if (father
== p
->real_parent
) {
701 /* reparent with a reaper, real father it's us */
702 p
->real_parent
= reaper
;
703 reparent_thread(p
, father
, 0);
705 /* reparent ptraced task to its real parent */
707 if (p
->exit_state
== EXIT_ZOMBIE
&& p
->exit_signal
!= -1 &&
708 thread_group_empty(p
))
709 do_notify_parent(p
, p
->exit_signal
);
713 * if the ptraced child is a zombie with exit_signal == -1
714 * we must collect it before we exit, or it will remain
715 * zombie forever since we prevented it from self-reap itself
716 * while it was being traced by us, to be able to see it in wait4.
718 if (unlikely(ptrace
&& p
->exit_state
== EXIT_ZOMBIE
&& p
->exit_signal
== -1))
719 list_add(&p
->ptrace_list
, &ptrace_dead
);
722 list_for_each_entry_safe(p
, n
, &father
->ptrace_children
, ptrace_list
) {
723 p
->real_parent
= reaper
;
724 reparent_thread(p
, father
, 1);
727 write_unlock_irq(&tasklist_lock
);
728 BUG_ON(!list_empty(&father
->children
));
729 BUG_ON(!list_empty(&father
->ptrace_children
));
731 list_for_each_entry_safe(p
, n
, &ptrace_dead
, ptrace_list
) {
732 list_del_init(&p
->ptrace_list
);
739 * Send signals to all our closest relatives so that they know
740 * to properly mourn us..
742 static void exit_notify(struct task_struct
*tsk
)
745 struct task_struct
*t
;
749 * This does two things:
751 * A. Make init inherit all the child processes
752 * B. Check to see if any process groups have become orphaned
753 * as a result of our exiting, and if they have any stopped
754 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
756 forget_original_parent(tsk
);
757 exit_task_namespaces(tsk
);
759 write_lock_irq(&tasklist_lock
);
761 * Check to see if any process groups have become orphaned
762 * as a result of our exiting, and if they have any stopped
763 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
765 * Case i: Our father is in a different pgrp than we are
766 * and we were the only connection outside, so our pgrp
767 * is about to become orphaned.
769 t
= tsk
->real_parent
;
771 pgrp
= task_pgrp(tsk
);
772 if ((task_pgrp(t
) != pgrp
) &&
773 (task_session(t
) == task_session(tsk
)) &&
774 will_become_orphaned_pgrp(pgrp
, tsk
) &&
775 has_stopped_jobs(pgrp
)) {
776 __kill_pgrp_info(SIGHUP
, SEND_SIG_PRIV
, pgrp
);
777 __kill_pgrp_info(SIGCONT
, SEND_SIG_PRIV
, pgrp
);
780 /* Let father know we died
782 * Thread signals are configurable, but you aren't going to use
783 * that to send signals to arbitary processes.
784 * That stops right now.
786 * If the parent exec id doesn't match the exec id we saved
787 * when we started then we know the parent has changed security
790 * If our self_exec id doesn't match our parent_exec_id then
791 * we have changed execution domain as these two values started
792 * the same after a fork.
794 if (tsk
->exit_signal
!= SIGCHLD
&& tsk
->exit_signal
!= -1 &&
795 ( tsk
->parent_exec_id
!= t
->self_exec_id
||
796 tsk
->self_exec_id
!= tsk
->parent_exec_id
)
797 && !capable(CAP_KILL
))
798 tsk
->exit_signal
= SIGCHLD
;
801 /* If something other than our normal parent is ptracing us, then
802 * send it a SIGCHLD instead of honoring exit_signal. exit_signal
803 * only has special meaning to our real parent.
805 if (tsk
->exit_signal
!= -1 && thread_group_empty(tsk
)) {
806 int signal
= tsk
->parent
== tsk
->real_parent
? tsk
->exit_signal
: SIGCHLD
;
807 do_notify_parent(tsk
, signal
);
808 } else if (tsk
->ptrace
) {
809 do_notify_parent(tsk
, SIGCHLD
);
813 if (tsk
->exit_signal
== -1 && likely(!tsk
->ptrace
))
815 tsk
->exit_state
= state
;
817 if (thread_group_leader(tsk
) &&
818 tsk
->signal
->notify_count
< 0 &&
819 tsk
->signal
->group_exit_task
)
820 wake_up_process(tsk
->signal
->group_exit_task
);
822 write_unlock_irq(&tasklist_lock
);
824 /* If the process is dead, release it - nobody will wait for it */
825 if (state
== EXIT_DEAD
)
829 #ifdef CONFIG_DEBUG_STACK_USAGE
830 static void check_stack_usage(void)
832 static DEFINE_SPINLOCK(low_water_lock
);
833 static int lowest_to_date
= THREAD_SIZE
;
834 unsigned long *n
= end_of_stack(current
);
839 free
= (unsigned long)n
- (unsigned long)end_of_stack(current
);
841 if (free
>= lowest_to_date
)
844 spin_lock(&low_water_lock
);
845 if (free
< lowest_to_date
) {
846 printk(KERN_WARNING
"%s used greatest stack depth: %lu bytes "
848 current
->comm
, free
);
849 lowest_to_date
= free
;
851 spin_unlock(&low_water_lock
);
854 static inline void check_stack_usage(void) {}
857 static inline void exit_child_reaper(struct task_struct
*tsk
)
859 if (likely(tsk
->group_leader
!= task_child_reaper(tsk
)))
862 if (tsk
->nsproxy
->pid_ns
== &init_pid_ns
)
863 panic("Attempted to kill init!");
866 * @tsk is the last thread in the 'cgroup-init' and is exiting.
867 * Terminate all remaining processes in the namespace and reap them
868 * before exiting @tsk.
870 * Note that @tsk (last thread of cgroup-init) may not necessarily
871 * be the child-reaper (i.e main thread of cgroup-init) of the
872 * namespace i.e the child_reaper may have already exited.
874 * Even after a child_reaper exits, we let it inherit orphaned children,
875 * because, pid_ns->child_reaper remains valid as long as there is
876 * at least one living sub-thread in the cgroup init.
878 * This living sub-thread of the cgroup-init will be notified when
879 * a child inherited by the 'child-reaper' exits (do_notify_parent()
880 * uses __group_send_sig_info()). Further, when reaping child processes,
881 * do_wait() iterates over children of all living sub threads.
883 * i.e even though 'child_reaper' thread is listed as the parent of the
884 * orphaned children, any living sub-thread in the cgroup-init can
885 * perform the role of the child_reaper.
887 zap_pid_ns_processes(tsk
->nsproxy
->pid_ns
);
890 NORET_TYPE
void do_exit(long code
)
892 struct task_struct
*tsk
= current
;
895 profile_task_exit(tsk
);
897 WARN_ON(atomic_read(&tsk
->fs_excl
));
899 if (unlikely(in_interrupt()))
900 panic("Aiee, killing interrupt handler!");
901 if (unlikely(!tsk
->pid
))
902 panic("Attempted to kill the idle task!");
904 if (unlikely(current
->ptrace
& PT_TRACE_EXIT
)) {
905 current
->ptrace_message
= code
;
906 ptrace_notify((PTRACE_EVENT_EXIT
<< 8) | SIGTRAP
);
910 * We're taking recursive faults here in do_exit. Safest is to just
911 * leave this task alone and wait for reboot.
913 if (unlikely(tsk
->flags
& PF_EXITING
)) {
915 "Fixing recursive fault but reboot is needed!\n");
917 * We can do this unlocked here. The futex code uses
918 * this flag just to verify whether the pi state
919 * cleanup has been done or not. In the worst case it
920 * loops once more. We pretend that the cleanup was
921 * done as there is no way to return. Either the
922 * OWNER_DIED bit is set by now or we push the blocked
923 * task into the wait for ever nirwana as well.
925 tsk
->flags
|= PF_EXITPIDONE
;
928 set_current_state(TASK_UNINTERRUPTIBLE
);
932 exit_signals(tsk
); /* sets PF_EXITING */
934 * tsk->flags are checked in the futex code to protect against
935 * an exiting task cleaning up the robust pi futexes.
938 spin_unlock_wait(&tsk
->pi_lock
);
940 if (unlikely(in_atomic()))
941 printk(KERN_INFO
"note: %s[%d] exited with preempt_count %d\n",
942 current
->comm
, task_pid_nr(current
),
945 acct_update_integrals(tsk
);
947 update_hiwater_rss(tsk
->mm
);
948 update_hiwater_vm(tsk
->mm
);
950 group_dead
= atomic_dec_and_test(&tsk
->signal
->live
);
952 exit_child_reaper(tsk
);
953 hrtimer_cancel(&tsk
->signal
->real_timer
);
954 exit_itimers(tsk
->signal
);
956 acct_collect(code
, group_dead
);
958 if (unlikely(tsk
->robust_list
))
959 exit_robust_list(tsk
);
961 if (unlikely(tsk
->compat_robust_list
))
962 compat_exit_robust_list(tsk
);
967 if (unlikely(tsk
->audit_context
))
970 tsk
->exit_code
= code
;
971 taskstats_exit(tsk
, group_dead
);
985 if (group_dead
&& tsk
->signal
->leader
)
986 disassociate_ctty(1);
988 module_put(task_thread_info(tsk
)->exec_domain
->module
);
990 module_put(tsk
->binfmt
->module
);
992 proc_exit_connector(tsk
);
995 mpol_free(tsk
->mempolicy
);
996 tsk
->mempolicy
= NULL
;
1000 * This must happen late, after the PID is not
1003 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
1004 exit_pi_state_list(tsk
);
1005 if (unlikely(current
->pi_state_cache
))
1006 kfree(current
->pi_state_cache
);
1009 * Make sure we are holding no locks:
1011 debug_check_no_locks_held(tsk
);
1013 * We can do this unlocked here. The futex code uses this flag
1014 * just to verify whether the pi state cleanup has been done
1015 * or not. In the worst case it loops once more.
1017 tsk
->flags
|= PF_EXITPIDONE
;
1019 if (tsk
->io_context
)
1022 if (tsk
->splice_pipe
)
1023 __free_pipe_info(tsk
->splice_pipe
);
1026 /* causes final put_task_struct in finish_task_switch(). */
1027 tsk
->state
= TASK_DEAD
;
1031 /* Avoid "noreturn function does return". */
1033 cpu_relax(); /* For when BUG is null */
1036 EXPORT_SYMBOL_GPL(do_exit
);
1038 NORET_TYPE
void complete_and_exit(struct completion
*comp
, long code
)
1046 EXPORT_SYMBOL(complete_and_exit
);
1048 asmlinkage
long sys_exit(int error_code
)
1050 do_exit((error_code
&0xff)<<8);
1054 * Take down every thread in the group. This is called by fatal signals
1055 * as well as by sys_exit_group (below).
1058 do_group_exit(int exit_code
)
1060 BUG_ON(exit_code
& 0x80); /* core dumps don't get here */
1062 if (current
->signal
->flags
& SIGNAL_GROUP_EXIT
)
1063 exit_code
= current
->signal
->group_exit_code
;
1064 else if (!thread_group_empty(current
)) {
1065 struct signal_struct
*const sig
= current
->signal
;
1066 struct sighand_struct
*const sighand
= current
->sighand
;
1067 spin_lock_irq(&sighand
->siglock
);
1068 if (signal_group_exit(sig
))
1069 /* Another thread got here before we took the lock. */
1070 exit_code
= sig
->group_exit_code
;
1072 sig
->group_exit_code
= exit_code
;
1073 sig
->flags
= SIGNAL_GROUP_EXIT
;
1074 zap_other_threads(current
);
1076 spin_unlock_irq(&sighand
->siglock
);
1084 * this kills every thread in the thread group. Note that any externally
1085 * wait4()-ing process will get the correct exit code - even if this
1086 * thread is not the thread group leader.
1088 asmlinkage
void sys_exit_group(int error_code
)
1090 do_group_exit((error_code
& 0xff) << 8);
1093 static struct pid
*task_pid_type(struct task_struct
*task
, enum pid_type type
)
1095 struct pid
*pid
= NULL
;
1096 if (type
== PIDTYPE_PID
)
1097 pid
= task
->pids
[type
].pid
;
1098 else if (type
< PIDTYPE_MAX
)
1099 pid
= task
->group_leader
->pids
[type
].pid
;
1103 static int eligible_child(enum pid_type type
, struct pid
*pid
, int options
,
1104 struct task_struct
*p
)
1108 if (type
< PIDTYPE_MAX
) {
1109 if (task_pid_type(p
, type
) != pid
)
1114 * Do not consider detached threads that are
1117 if (p
->exit_signal
== -1 && !p
->ptrace
)
1120 /* Wait for all children (clone and not) if __WALL is set;
1121 * otherwise, wait for clone children *only* if __WCLONE is
1122 * set; otherwise, wait for non-clone children *only*. (Note:
1123 * A "clone" child here is one that reports to its parent
1124 * using a signal other than SIGCHLD.) */
1125 if (((p
->exit_signal
!= SIGCHLD
) ^ ((options
& __WCLONE
) != 0))
1126 && !(options
& __WALL
))
1129 err
= security_task_wait(p
);
1133 if (type
!= PIDTYPE_PID
)
1135 /* This child was explicitly requested, abort */
1136 read_unlock(&tasklist_lock
);
1140 static int wait_noreap_copyout(struct task_struct
*p
, pid_t pid
, uid_t uid
,
1141 int why
, int status
,
1142 struct siginfo __user
*infop
,
1143 struct rusage __user
*rusagep
)
1145 int retval
= rusagep
? getrusage(p
, RUSAGE_BOTH
, rusagep
) : 0;
1149 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1151 retval
= put_user(0, &infop
->si_errno
);
1153 retval
= put_user((short)why
, &infop
->si_code
);
1155 retval
= put_user(pid
, &infop
->si_pid
);
1157 retval
= put_user(uid
, &infop
->si_uid
);
1159 retval
= put_user(status
, &infop
->si_status
);
1166 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1167 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1168 * the lock and this task is uninteresting. If we return nonzero, we have
1169 * released the lock and the system call should return.
1171 static int wait_task_zombie(struct task_struct
*p
, int noreap
,
1172 struct siginfo __user
*infop
,
1173 int __user
*stat_addr
, struct rusage __user
*ru
)
1175 unsigned long state
;
1176 int retval
, status
, traced
;
1177 pid_t pid
= task_pid_vnr(p
);
1179 if (unlikely(noreap
)) {
1181 int exit_code
= p
->exit_code
;
1185 read_unlock(&tasklist_lock
);
1186 if ((exit_code
& 0x7f) == 0) {
1188 status
= exit_code
>> 8;
1190 why
= (exit_code
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
1191 status
= exit_code
& 0x7f;
1193 return wait_noreap_copyout(p
, pid
, uid
, why
,
1198 * Try to move the task's state to DEAD
1199 * only one thread is allowed to do this:
1201 state
= xchg(&p
->exit_state
, EXIT_DEAD
);
1202 if (state
!= EXIT_ZOMBIE
) {
1203 BUG_ON(state
!= EXIT_DEAD
);
1207 /* traced means p->ptrace, but not vice versa */
1208 traced
= (p
->real_parent
!= p
->parent
);
1210 if (likely(!traced
)) {
1211 struct signal_struct
*psig
;
1212 struct signal_struct
*sig
;
1215 * The resource counters for the group leader are in its
1216 * own task_struct. Those for dead threads in the group
1217 * are in its signal_struct, as are those for the child
1218 * processes it has previously reaped. All these
1219 * accumulate in the parent's signal_struct c* fields.
1221 * We don't bother to take a lock here to protect these
1222 * p->signal fields, because they are only touched by
1223 * __exit_signal, which runs with tasklist_lock
1224 * write-locked anyway, and so is excluded here. We do
1225 * need to protect the access to p->parent->signal fields,
1226 * as other threads in the parent group can be right
1227 * here reaping other children at the same time.
1229 spin_lock_irq(&p
->parent
->sighand
->siglock
);
1230 psig
= p
->parent
->signal
;
1233 cputime_add(psig
->cutime
,
1234 cputime_add(p
->utime
,
1235 cputime_add(sig
->utime
,
1238 cputime_add(psig
->cstime
,
1239 cputime_add(p
->stime
,
1240 cputime_add(sig
->stime
,
1243 cputime_add(psig
->cgtime
,
1244 cputime_add(p
->gtime
,
1245 cputime_add(sig
->gtime
,
1248 p
->min_flt
+ sig
->min_flt
+ sig
->cmin_flt
;
1250 p
->maj_flt
+ sig
->maj_flt
+ sig
->cmaj_flt
;
1252 p
->nvcsw
+ sig
->nvcsw
+ sig
->cnvcsw
;
1254 p
->nivcsw
+ sig
->nivcsw
+ sig
->cnivcsw
;
1256 task_io_get_inblock(p
) +
1257 sig
->inblock
+ sig
->cinblock
;
1259 task_io_get_oublock(p
) +
1260 sig
->oublock
+ sig
->coublock
;
1261 spin_unlock_irq(&p
->parent
->sighand
->siglock
);
1265 * Now we are sure this task is interesting, and no other
1266 * thread can reap it because we set its state to EXIT_DEAD.
1268 read_unlock(&tasklist_lock
);
1270 retval
= ru
? getrusage(p
, RUSAGE_BOTH
, ru
) : 0;
1271 status
= (p
->signal
->flags
& SIGNAL_GROUP_EXIT
)
1272 ? p
->signal
->group_exit_code
: p
->exit_code
;
1273 if (!retval
&& stat_addr
)
1274 retval
= put_user(status
, stat_addr
);
1275 if (!retval
&& infop
)
1276 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1277 if (!retval
&& infop
)
1278 retval
= put_user(0, &infop
->si_errno
);
1279 if (!retval
&& infop
) {
1282 if ((status
& 0x7f) == 0) {
1286 why
= (status
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
1289 retval
= put_user((short)why
, &infop
->si_code
);
1291 retval
= put_user(status
, &infop
->si_status
);
1293 if (!retval
&& infop
)
1294 retval
= put_user(pid
, &infop
->si_pid
);
1295 if (!retval
&& infop
)
1296 retval
= put_user(p
->uid
, &infop
->si_uid
);
1301 write_lock_irq(&tasklist_lock
);
1302 /* We dropped tasklist, ptracer could die and untrace */
1305 * If this is not a detached task, notify the parent.
1306 * If it's still not detached after that, don't release
1309 if (p
->exit_signal
!= -1) {
1310 do_notify_parent(p
, p
->exit_signal
);
1311 if (p
->exit_signal
!= -1) {
1312 p
->exit_state
= EXIT_ZOMBIE
;
1316 write_unlock_irq(&tasklist_lock
);
1325 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1326 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1327 * the lock and this task is uninteresting. If we return nonzero, we have
1328 * released the lock and the system call should return.
1330 static int wait_task_stopped(struct task_struct
*p
,
1331 int noreap
, struct siginfo __user
*infop
,
1332 int __user
*stat_addr
, struct rusage __user
*ru
)
1334 int retval
, exit_code
, why
;
1335 uid_t uid
= 0; /* unneeded, required by compiler */
1339 spin_lock_irq(&p
->sighand
->siglock
);
1341 if (unlikely(!task_is_stopped_or_traced(p
)))
1344 if (!(p
->ptrace
& PT_PTRACED
) && p
->signal
->group_stop_count
> 0)
1346 * A group stop is in progress and this is the group leader.
1347 * We won't report until all threads have stopped.
1351 exit_code
= p
->exit_code
;
1360 spin_unlock_irq(&p
->sighand
->siglock
);
1365 * Now we are pretty sure this task is interesting.
1366 * Make sure it doesn't get reaped out from under us while we
1367 * give up the lock and then examine it below. We don't want to
1368 * keep holding onto the tasklist_lock while we call getrusage and
1369 * possibly take page faults for user memory.
1372 pid
= task_pid_vnr(p
);
1373 why
= (p
->ptrace
& PT_PTRACED
) ? CLD_TRAPPED
: CLD_STOPPED
;
1374 read_unlock(&tasklist_lock
);
1376 if (unlikely(noreap
))
1377 return wait_noreap_copyout(p
, pid
, uid
,
1381 retval
= ru
? getrusage(p
, RUSAGE_BOTH
, ru
) : 0;
1382 if (!retval
&& stat_addr
)
1383 retval
= put_user((exit_code
<< 8) | 0x7f, stat_addr
);
1384 if (!retval
&& infop
)
1385 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1386 if (!retval
&& infop
)
1387 retval
= put_user(0, &infop
->si_errno
);
1388 if (!retval
&& infop
)
1389 retval
= put_user(why
, &infop
->si_code
);
1390 if (!retval
&& infop
)
1391 retval
= put_user(exit_code
, &infop
->si_status
);
1392 if (!retval
&& infop
)
1393 retval
= put_user(pid
, &infop
->si_pid
);
1394 if (!retval
&& infop
)
1395 retval
= put_user(uid
, &infop
->si_uid
);
1405 * Handle do_wait work for one task in a live, non-stopped state.
1406 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1407 * the lock and this task is uninteresting. If we return nonzero, we have
1408 * released the lock and the system call should return.
1410 static int wait_task_continued(struct task_struct
*p
, int noreap
,
1411 struct siginfo __user
*infop
,
1412 int __user
*stat_addr
, struct rusage __user
*ru
)
1418 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
))
1421 spin_lock_irq(&p
->sighand
->siglock
);
1422 /* Re-check with the lock held. */
1423 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
)) {
1424 spin_unlock_irq(&p
->sighand
->siglock
);
1428 p
->signal
->flags
&= ~SIGNAL_STOP_CONTINUED
;
1429 spin_unlock_irq(&p
->sighand
->siglock
);
1431 pid
= task_pid_vnr(p
);
1434 read_unlock(&tasklist_lock
);
1437 retval
= ru
? getrusage(p
, RUSAGE_BOTH
, ru
) : 0;
1439 if (!retval
&& stat_addr
)
1440 retval
= put_user(0xffff, stat_addr
);
1444 retval
= wait_noreap_copyout(p
, pid
, uid
,
1445 CLD_CONTINUED
, SIGCONT
,
1447 BUG_ON(retval
== 0);
1453 static long do_wait(enum pid_type type
, struct pid
*pid
, int options
,
1454 struct siginfo __user
*infop
, int __user
*stat_addr
,
1455 struct rusage __user
*ru
)
1457 DECLARE_WAITQUEUE(wait
, current
);
1458 struct task_struct
*tsk
;
1461 add_wait_queue(¤t
->signal
->wait_chldexit
,&wait
);
1463 /* If there is nothing that can match our critier just get out */
1465 if ((type
< PIDTYPE_MAX
) && (!pid
|| hlist_empty(&pid
->tasks
[type
])))
1469 * We will set this flag if we see any child that might later
1470 * match our criteria, even if we are not able to reap it yet.
1473 current
->state
= TASK_INTERRUPTIBLE
;
1474 read_lock(&tasklist_lock
);
1477 struct task_struct
*p
;
1479 list_for_each_entry(p
, &tsk
->children
, sibling
) {
1480 int ret
= eligible_child(type
, pid
, options
, p
);
1484 if (unlikely(ret
< 0)) {
1486 } else if (task_is_stopped_or_traced(p
)) {
1488 * It's stopped now, so it might later
1489 * continue, exit, or stop again.
1492 if (!(p
->ptrace
& PT_PTRACED
) &&
1493 !(options
& WUNTRACED
))
1496 retval
= wait_task_stopped(p
,
1497 (options
& WNOWAIT
), infop
,
1499 } else if (p
->exit_state
== EXIT_ZOMBIE
&&
1500 !delay_group_leader(p
)) {
1502 * We don't reap group leaders with subthreads.
1504 if (!likely(options
& WEXITED
))
1506 retval
= wait_task_zombie(p
,
1507 (options
& WNOWAIT
), infop
,
1509 } else if (p
->exit_state
!= EXIT_DEAD
) {
1511 * It's running now, so it might later
1512 * exit, stop, or stop and then continue.
1515 if (!unlikely(options
& WCONTINUED
))
1517 retval
= wait_task_continued(p
,
1518 (options
& WNOWAIT
), infop
,
1521 if (retval
!= 0) /* tasklist_lock released */
1525 list_for_each_entry(p
, &tsk
->ptrace_children
,
1527 flag
= eligible_child(type
, pid
, options
, p
);
1530 if (likely(flag
> 0))
1536 if (options
& __WNOTHREAD
)
1538 tsk
= next_thread(tsk
);
1539 BUG_ON(tsk
->signal
!= current
->signal
);
1540 } while (tsk
!= current
);
1541 read_unlock(&tasklist_lock
);
1544 if (options
& WNOHANG
)
1546 retval
= -ERESTARTSYS
;
1547 if (signal_pending(current
))
1554 current
->state
= TASK_RUNNING
;
1555 remove_wait_queue(¤t
->signal
->wait_chldexit
,&wait
);
1561 * For a WNOHANG return, clear out all the fields
1562 * we would set so the user can easily tell the
1566 retval
= put_user(0, &infop
->si_signo
);
1568 retval
= put_user(0, &infop
->si_errno
);
1570 retval
= put_user(0, &infop
->si_code
);
1572 retval
= put_user(0, &infop
->si_pid
);
1574 retval
= put_user(0, &infop
->si_uid
);
1576 retval
= put_user(0, &infop
->si_status
);
1582 asmlinkage
long sys_waitid(int which
, pid_t upid
,
1583 struct siginfo __user
*infop
, int options
,
1584 struct rusage __user
*ru
)
1586 struct pid
*pid
= NULL
;
1590 if (options
& ~(WNOHANG
|WNOWAIT
|WEXITED
|WSTOPPED
|WCONTINUED
))
1592 if (!(options
& (WEXITED
|WSTOPPED
|WCONTINUED
)))
1605 type
= PIDTYPE_PGID
;
1613 if (type
< PIDTYPE_MAX
)
1614 pid
= find_get_pid(upid
);
1615 ret
= do_wait(type
, pid
, options
, infop
, NULL
, ru
);
1618 /* avoid REGPARM breakage on x86: */
1619 prevent_tail_call(ret
);
1623 asmlinkage
long sys_wait4(pid_t upid
, int __user
*stat_addr
,
1624 int options
, struct rusage __user
*ru
)
1626 struct pid
*pid
= NULL
;
1630 if (options
& ~(WNOHANG
|WUNTRACED
|WCONTINUED
|
1631 __WNOTHREAD
|__WCLONE
|__WALL
))
1636 else if (upid
< 0) {
1637 type
= PIDTYPE_PGID
;
1638 pid
= find_get_pid(-upid
);
1639 } else if (upid
== 0) {
1640 type
= PIDTYPE_PGID
;
1641 pid
= get_pid(task_pgrp(current
));
1642 } else /* upid > 0 */ {
1644 pid
= find_get_pid(upid
);
1647 ret
= do_wait(type
, pid
, options
| WEXITED
, NULL
, stat_addr
, ru
);
1650 /* avoid REGPARM breakage on x86: */
1651 prevent_tail_call(ret
);
1655 #ifdef __ARCH_WANT_SYS_WAITPID
1658 * sys_waitpid() remains for compatibility. waitpid() should be
1659 * implemented by calling sys_wait4() from libc.a.
1661 asmlinkage
long sys_waitpid(pid_t pid
, int __user
*stat_addr
, int options
)
1663 return sys_wait4(pid
, stat_addr
, options
, NULL
);