4 * Copyright (C) 1991, 1992 Linus Torvalds
8 #include <linux/slab.h>
9 #include <linux/interrupt.h>
10 #include <linux/smp_lock.h>
11 #include <linux/module.h>
12 #include <linux/capability.h>
13 #include <linux/completion.h>
14 #include <linux/personality.h>
15 #include <linux/tty.h>
16 #include <linux/namespace.h>
17 #include <linux/key.h>
18 #include <linux/security.h>
19 #include <linux/cpu.h>
20 #include <linux/acct.h>
21 #include <linux/tsacct_kern.h>
22 #include <linux/file.h>
23 #include <linux/binfmts.h>
24 #include <linux/nsproxy.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/mempolicy.h>
30 #include <linux/taskstats_kern.h>
31 #include <linux/delayacct.h>
32 #include <linux/cpuset.h>
33 #include <linux/syscalls.h>
34 #include <linux/signal.h>
35 #include <linux/posix-timers.h>
36 #include <linux/cn_proc.h>
37 #include <linux/mutex.h>
38 #include <linux/futex.h>
39 #include <linux/compat.h>
40 #include <linux/pipe_fs_i.h>
41 #include <linux/audit.h> /* for audit_free() */
42 #include <linux/resource.h>
43 #include <linux/blkdev.h>
45 #include <asm/uaccess.h>
46 #include <asm/unistd.h>
47 #include <asm/pgtable.h>
48 #include <asm/mmu_context.h>
50 extern void sem_exit (void);
51 extern struct task_struct
*child_reaper
;
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
);
95 sig
->group_exit_task
= NULL
;
97 if (tsk
== sig
->curr_target
)
98 sig
->curr_target
= next_thread(tsk
);
100 * Accumulate here the counters for all threads but the
101 * group leader as they die, so they can be added into
102 * the process-wide totals when those are taken.
103 * The group leader stays around as a zombie as long
104 * as there are other threads. When it gets reaped,
105 * the exit.c code will add its counts into these totals.
106 * We won't ever get here for the group leader, since it
107 * will have been the last reference on the signal_struct.
109 sig
->utime
= cputime_add(sig
->utime
, tsk
->utime
);
110 sig
->stime
= cputime_add(sig
->stime
, tsk
->stime
);
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
->sched_time
+= tsk
->sched_time
;
116 sig
= NULL
; /* Marker for below. */
119 __unhash_process(tsk
);
123 spin_unlock(&sighand
->siglock
);
126 __cleanup_sighand(sighand
);
127 clear_tsk_thread_flag(tsk
,TIF_SIGPENDING
);
128 flush_sigqueue(&tsk
->pending
);
130 flush_sigqueue(&sig
->shared_pending
);
131 taskstats_tgid_free(sig
);
132 __cleanup_signal(sig
);
136 static void delayed_put_task_struct(struct rcu_head
*rhp
)
138 put_task_struct(container_of(rhp
, struct task_struct
, rcu
));
141 void release_task(struct task_struct
* p
)
143 struct task_struct
*leader
;
146 atomic_dec(&p
->user
->processes
);
147 write_lock_irq(&tasklist_lock
);
149 BUG_ON(!list_empty(&p
->ptrace_list
) || !list_empty(&p
->ptrace_children
));
153 * If we are the last non-leader member of the thread
154 * group, and the leader is zombie, then notify the
155 * group leader's parent process. (if it wants notification.)
158 leader
= p
->group_leader
;
159 if (leader
!= p
&& thread_group_empty(leader
) && leader
->exit_state
== EXIT_ZOMBIE
) {
160 BUG_ON(leader
->exit_signal
== -1);
161 do_notify_parent(leader
, leader
->exit_signal
);
163 * If we were the last child thread and the leader has
164 * exited already, and the leader's parent ignores SIGCHLD,
165 * then we are the one who should release the leader.
167 * do_notify_parent() will have marked it self-reaping in
170 zap_leader
= (leader
->exit_signal
== -1);
174 write_unlock_irq(&tasklist_lock
);
177 call_rcu(&p
->rcu
, delayed_put_task_struct
);
180 if (unlikely(zap_leader
))
185 * This checks not only the pgrp, but falls back on the pid if no
186 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
189 int session_of_pgrp(int pgrp
)
191 struct task_struct
*p
;
194 read_lock(&tasklist_lock
);
195 do_each_task_pid(pgrp
, PIDTYPE_PGID
, p
) {
196 if (p
->signal
->session
> 0) {
197 sid
= p
->signal
->session
;
200 } while_each_task_pid(pgrp
, PIDTYPE_PGID
, p
);
201 p
= find_task_by_pid(pgrp
);
203 sid
= p
->signal
->session
;
205 read_unlock(&tasklist_lock
);
211 * Determine if a process group is "orphaned", according to the POSIX
212 * definition in 2.2.2.52. Orphaned process groups are not to be affected
213 * by terminal-generated stop signals. Newly orphaned process groups are
214 * to receive a SIGHUP and a SIGCONT.
216 * "I ask you, have you ever known what it is to be an orphan?"
218 static int will_become_orphaned_pgrp(int pgrp
, struct task_struct
*ignored_task
)
220 struct task_struct
*p
;
223 do_each_task_pid(pgrp
, PIDTYPE_PGID
, p
) {
224 if (p
== ignored_task
226 || is_init(p
->real_parent
))
228 if (process_group(p
->real_parent
) != pgrp
229 && p
->real_parent
->signal
->session
== p
->signal
->session
) {
233 } while_each_task_pid(pgrp
, PIDTYPE_PGID
, p
);
234 return ret
; /* (sighing) "Often!" */
237 int is_orphaned_pgrp(int pgrp
)
241 read_lock(&tasklist_lock
);
242 retval
= will_become_orphaned_pgrp(pgrp
, NULL
);
243 read_unlock(&tasklist_lock
);
248 static int has_stopped_jobs(int pgrp
)
251 struct task_struct
*p
;
253 do_each_task_pid(pgrp
, PIDTYPE_PGID
, p
) {
254 if (p
->state
!= TASK_STOPPED
)
258 } while_each_task_pid(pgrp
, PIDTYPE_PGID
, p
);
263 * reparent_to_init - Reparent the calling kernel thread to the init task.
265 * If a kernel thread is launched as a result of a system call, or if
266 * it ever exits, it should generally reparent itself to init so that
267 * it is correctly cleaned up on exit.
269 * The various task state such as scheduling policy and priority may have
270 * been inherited from a user process, so we reset them to sane values here.
272 * NOTE that reparent_to_init() gives the caller full capabilities.
274 static void reparent_to_init(void)
276 write_lock_irq(&tasklist_lock
);
278 ptrace_unlink(current
);
279 /* Reparent to init */
280 remove_parent(current
);
281 current
->parent
= child_reaper
;
282 current
->real_parent
= child_reaper
;
285 /* Set the exit signal to SIGCHLD so we signal init on exit */
286 current
->exit_signal
= SIGCHLD
;
288 if (!has_rt_policy(current
) && (task_nice(current
) < 0))
289 set_user_nice(current
, 0);
293 security_task_reparent_to_init(current
);
294 memcpy(current
->signal
->rlim
, init_task
.signal
->rlim
,
295 sizeof(current
->signal
->rlim
));
296 atomic_inc(&(INIT_USER
->__count
));
297 write_unlock_irq(&tasklist_lock
);
298 switch_uid(INIT_USER
);
301 void __set_special_pids(pid_t session
, pid_t pgrp
)
303 struct task_struct
*curr
= current
->group_leader
;
305 if (curr
->signal
->session
!= session
) {
306 detach_pid(curr
, PIDTYPE_SID
);
307 curr
->signal
->session
= session
;
308 attach_pid(curr
, PIDTYPE_SID
, session
);
310 if (process_group(curr
) != pgrp
) {
311 detach_pid(curr
, PIDTYPE_PGID
);
312 curr
->signal
->pgrp
= pgrp
;
313 attach_pid(curr
, PIDTYPE_PGID
, pgrp
);
317 void set_special_pids(pid_t session
, pid_t pgrp
)
319 write_lock_irq(&tasklist_lock
);
320 __set_special_pids(session
, pgrp
);
321 write_unlock_irq(&tasklist_lock
);
325 * Let kernel threads use this to say that they
326 * allow a certain signal (since daemonize() will
327 * have disabled all of them by default).
329 int allow_signal(int sig
)
331 if (!valid_signal(sig
) || sig
< 1)
334 spin_lock_irq(¤t
->sighand
->siglock
);
335 sigdelset(¤t
->blocked
, sig
);
337 /* Kernel threads handle their own signals.
338 Let the signal code know it'll be handled, so
339 that they don't get converted to SIGKILL or
340 just silently dropped */
341 current
->sighand
->action
[(sig
)-1].sa
.sa_handler
= (void __user
*)2;
344 spin_unlock_irq(¤t
->sighand
->siglock
);
348 EXPORT_SYMBOL(allow_signal
);
350 int disallow_signal(int sig
)
352 if (!valid_signal(sig
) || sig
< 1)
355 spin_lock_irq(¤t
->sighand
->siglock
);
356 sigaddset(¤t
->blocked
, sig
);
358 spin_unlock_irq(¤t
->sighand
->siglock
);
362 EXPORT_SYMBOL(disallow_signal
);
365 * Put all the gunge required to become a kernel thread without
366 * attached user resources in one place where it belongs.
369 void daemonize(const char *name
, ...)
372 struct fs_struct
*fs
;
375 va_start(args
, name
);
376 vsnprintf(current
->comm
, sizeof(current
->comm
), name
, args
);
380 * If we were started as result of loading a module, close all of the
381 * user space pages. We don't need them, and if we didn't close them
382 * they would be locked into memory.
386 set_special_pids(1, 1);
387 mutex_lock(&tty_mutex
);
388 current
->signal
->tty
= NULL
;
389 mutex_unlock(&tty_mutex
);
391 /* Block and flush all signals */
392 sigfillset(&blocked
);
393 sigprocmask(SIG_BLOCK
, &blocked
, NULL
);
394 flush_signals(current
);
396 /* Become as one with the init task */
398 exit_fs(current
); /* current->fs->count--; */
401 atomic_inc(&fs
->count
);
403 exit_task_namespaces(current
);
404 current
->nsproxy
= init_task
.nsproxy
;
405 get_task_namespaces(current
);
408 current
->files
= init_task
.files
;
409 atomic_inc(¤t
->files
->count
);
414 EXPORT_SYMBOL(daemonize
);
416 static void close_files(struct files_struct
* files
)
424 * It is safe to dereference the fd table without RCU or
425 * ->file_lock because this is the last reference to the
428 fdt
= files_fdtable(files
);
432 if (i
>= fdt
->max_fdset
|| i
>= fdt
->max_fds
)
434 set
= fdt
->open_fds
->fds_bits
[j
++];
437 struct file
* file
= xchg(&fdt
->fd
[i
], NULL
);
439 filp_close(file
, files
);
447 struct files_struct
*get_files_struct(struct task_struct
*task
)
449 struct files_struct
*files
;
454 atomic_inc(&files
->count
);
460 void fastcall
put_files_struct(struct files_struct
*files
)
464 if (atomic_dec_and_test(&files
->count
)) {
467 * Free the fd and fdset arrays if we expanded them.
468 * If the fdtable was embedded, pass files for freeing
469 * at the end of the RCU grace period. Otherwise,
470 * you can free files immediately.
472 fdt
= files_fdtable(files
);
473 if (fdt
== &files
->fdtab
)
474 fdt
->free_files
= files
;
476 kmem_cache_free(files_cachep
, files
);
481 EXPORT_SYMBOL(put_files_struct
);
483 void reset_files_struct(struct task_struct
*tsk
, struct files_struct
*files
)
485 struct files_struct
*old
;
491 put_files_struct(old
);
493 EXPORT_SYMBOL(reset_files_struct
);
495 static inline void __exit_files(struct task_struct
*tsk
)
497 struct files_struct
* files
= tsk
->files
;
503 put_files_struct(files
);
507 void exit_files(struct task_struct
*tsk
)
512 static inline void __put_fs_struct(struct fs_struct
*fs
)
514 /* No need to hold fs->lock if we are killing it */
515 if (atomic_dec_and_test(&fs
->count
)) {
522 mntput(fs
->altrootmnt
);
524 kmem_cache_free(fs_cachep
, fs
);
528 void put_fs_struct(struct fs_struct
*fs
)
533 static inline void __exit_fs(struct task_struct
*tsk
)
535 struct fs_struct
* fs
= tsk
->fs
;
545 void exit_fs(struct task_struct
*tsk
)
550 EXPORT_SYMBOL_GPL(exit_fs
);
553 * Turn us into a lazy TLB process if we
556 static void exit_mm(struct task_struct
* tsk
)
558 struct mm_struct
*mm
= tsk
->mm
;
564 * Serialize with any possible pending coredump.
565 * We must hold mmap_sem around checking core_waiters
566 * and clearing tsk->mm. The core-inducing thread
567 * will increment core_waiters for each thread in the
568 * group with ->mm != NULL.
570 down_read(&mm
->mmap_sem
);
571 if (mm
->core_waiters
) {
572 up_read(&mm
->mmap_sem
);
573 down_write(&mm
->mmap_sem
);
574 if (!--mm
->core_waiters
)
575 complete(mm
->core_startup_done
);
576 up_write(&mm
->mmap_sem
);
578 wait_for_completion(&mm
->core_done
);
579 down_read(&mm
->mmap_sem
);
581 atomic_inc(&mm
->mm_count
);
582 BUG_ON(mm
!= tsk
->active_mm
);
583 /* more a memory barrier than a real lock */
586 up_read(&mm
->mmap_sem
);
587 enter_lazy_tlb(mm
, current
);
593 choose_new_parent(struct task_struct
*p
, struct task_struct
*reaper
)
596 * Make sure we're not reparenting to ourselves and that
597 * the parent is not a zombie.
599 BUG_ON(p
== reaper
|| reaper
->exit_state
);
600 p
->real_parent
= reaper
;
604 reparent_thread(struct task_struct
*p
, struct task_struct
*father
, int traced
)
606 /* We don't want people slaying init. */
607 if (p
->exit_signal
!= -1)
608 p
->exit_signal
= SIGCHLD
;
610 if (p
->pdeath_signal
)
611 /* We already hold the tasklist_lock here. */
612 group_send_sig_info(p
->pdeath_signal
, SEND_SIG_NOINFO
, p
);
614 /* Move the child from its dying parent to the new one. */
615 if (unlikely(traced
)) {
616 /* Preserve ptrace links if someone else is tracing this child. */
617 list_del_init(&p
->ptrace_list
);
618 if (p
->parent
!= p
->real_parent
)
619 list_add(&p
->ptrace_list
, &p
->real_parent
->ptrace_children
);
621 /* If this child is being traced, then we're the one tracing it
622 * anyway, so let go of it.
626 p
->parent
= p
->real_parent
;
629 /* If we'd notified the old parent about this child's death,
630 * also notify the new parent.
632 if (p
->exit_state
== EXIT_ZOMBIE
&& p
->exit_signal
!= -1 &&
633 thread_group_empty(p
))
634 do_notify_parent(p
, p
->exit_signal
);
635 else if (p
->state
== TASK_TRACED
) {
637 * If it was at a trace stop, turn it into
638 * a normal stop since it's no longer being
646 * process group orphan check
647 * Case ii: Our child is in a different pgrp
648 * than we are, and it was the only connection
649 * outside, so the child pgrp is now orphaned.
651 if ((process_group(p
) != process_group(father
)) &&
652 (p
->signal
->session
== father
->signal
->session
)) {
653 int pgrp
= process_group(p
);
655 if (will_become_orphaned_pgrp(pgrp
, NULL
) && has_stopped_jobs(pgrp
)) {
656 __kill_pg_info(SIGHUP
, SEND_SIG_PRIV
, pgrp
);
657 __kill_pg_info(SIGCONT
, SEND_SIG_PRIV
, pgrp
);
663 * When we die, we re-parent all our children.
664 * Try to give them to another thread in our thread
665 * group, and if no such member exists, give it to
666 * the global child reaper process (ie "init")
669 forget_original_parent(struct task_struct
*father
, struct list_head
*to_release
)
671 struct task_struct
*p
, *reaper
= father
;
672 struct list_head
*_p
, *_n
;
675 reaper
= next_thread(reaper
);
676 if (reaper
== father
) {
677 reaper
= child_reaper
;
680 } while (reaper
->exit_state
);
683 * There are only two places where our children can be:
685 * - in our child list
686 * - in our ptraced child list
688 * Search them and reparent children.
690 list_for_each_safe(_p
, _n
, &father
->children
) {
692 p
= list_entry(_p
, struct task_struct
, sibling
);
696 /* if father isn't the real parent, then ptrace must be enabled */
697 BUG_ON(father
!= p
->real_parent
&& !ptrace
);
699 if (father
== p
->real_parent
) {
700 /* reparent with a reaper, real father it's us */
701 choose_new_parent(p
, reaper
);
702 reparent_thread(p
, father
, 0);
704 /* reparent ptraced task to its real parent */
706 if (p
->exit_state
== EXIT_ZOMBIE
&& p
->exit_signal
!= -1 &&
707 thread_group_empty(p
))
708 do_notify_parent(p
, p
->exit_signal
);
712 * if the ptraced child is a zombie with exit_signal == -1
713 * we must collect it before we exit, or it will remain
714 * zombie forever since we prevented it from self-reap itself
715 * while it was being traced by us, to be able to see it in wait4.
717 if (unlikely(ptrace
&& p
->exit_state
== EXIT_ZOMBIE
&& p
->exit_signal
== -1))
718 list_add(&p
->ptrace_list
, to_release
);
720 list_for_each_safe(_p
, _n
, &father
->ptrace_children
) {
721 p
= list_entry(_p
, struct task_struct
, ptrace_list
);
722 choose_new_parent(p
, reaper
);
723 reparent_thread(p
, father
, 1);
728 * Send signals to all our closest relatives so that they know
729 * to properly mourn us..
731 static void exit_notify(struct task_struct
*tsk
)
734 struct task_struct
*t
;
735 struct list_head ptrace_dead
, *_p
, *_n
;
737 if (signal_pending(tsk
) && !(tsk
->signal
->flags
& SIGNAL_GROUP_EXIT
)
738 && !thread_group_empty(tsk
)) {
740 * This occurs when there was a race between our exit
741 * syscall and a group signal choosing us as the one to
742 * wake up. It could be that we are the only thread
743 * alerted to check for pending signals, but another thread
744 * should be woken now to take the signal since we will not.
745 * Now we'll wake all the threads in the group just to make
746 * sure someone gets all the pending signals.
748 read_lock(&tasklist_lock
);
749 spin_lock_irq(&tsk
->sighand
->siglock
);
750 for (t
= next_thread(tsk
); t
!= tsk
; t
= next_thread(t
))
751 if (!signal_pending(t
) && !(t
->flags
& PF_EXITING
)) {
752 recalc_sigpending_tsk(t
);
753 if (signal_pending(t
))
754 signal_wake_up(t
, 0);
756 spin_unlock_irq(&tsk
->sighand
->siglock
);
757 read_unlock(&tasklist_lock
);
760 write_lock_irq(&tasklist_lock
);
763 * This does two things:
765 * A. Make init inherit all the child processes
766 * B. Check to see if any process groups have become orphaned
767 * as a result of our exiting, and if they have any stopped
768 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
771 INIT_LIST_HEAD(&ptrace_dead
);
772 forget_original_parent(tsk
, &ptrace_dead
);
773 BUG_ON(!list_empty(&tsk
->children
));
774 BUG_ON(!list_empty(&tsk
->ptrace_children
));
777 * Check to see if any process groups have become orphaned
778 * as a result of our exiting, and if they have any stopped
779 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
781 * Case i: Our father is in a different pgrp than we are
782 * and we were the only connection outside, so our pgrp
783 * is about to become orphaned.
786 t
= tsk
->real_parent
;
788 if ((process_group(t
) != process_group(tsk
)) &&
789 (t
->signal
->session
== tsk
->signal
->session
) &&
790 will_become_orphaned_pgrp(process_group(tsk
), tsk
) &&
791 has_stopped_jobs(process_group(tsk
))) {
792 __kill_pg_info(SIGHUP
, SEND_SIG_PRIV
, process_group(tsk
));
793 __kill_pg_info(SIGCONT
, SEND_SIG_PRIV
, process_group(tsk
));
796 /* Let father know we died
798 * Thread signals are configurable, but you aren't going to use
799 * that to send signals to arbitary processes.
800 * That stops right now.
802 * If the parent exec id doesn't match the exec id we saved
803 * when we started then we know the parent has changed security
806 * If our self_exec id doesn't match our parent_exec_id then
807 * we have changed execution domain as these two values started
808 * the same after a fork.
812 if (tsk
->exit_signal
!= SIGCHLD
&& tsk
->exit_signal
!= -1 &&
813 ( tsk
->parent_exec_id
!= t
->self_exec_id
||
814 tsk
->self_exec_id
!= tsk
->parent_exec_id
)
815 && !capable(CAP_KILL
))
816 tsk
->exit_signal
= SIGCHLD
;
819 /* If something other than our normal parent is ptracing us, then
820 * send it a SIGCHLD instead of honoring exit_signal. exit_signal
821 * only has special meaning to our real parent.
823 if (tsk
->exit_signal
!= -1 && thread_group_empty(tsk
)) {
824 int signal
= tsk
->parent
== tsk
->real_parent
? tsk
->exit_signal
: SIGCHLD
;
825 do_notify_parent(tsk
, signal
);
826 } else if (tsk
->ptrace
) {
827 do_notify_parent(tsk
, SIGCHLD
);
831 if (tsk
->exit_signal
== -1 &&
832 (likely(tsk
->ptrace
== 0) ||
833 unlikely(tsk
->parent
->signal
->flags
& SIGNAL_GROUP_EXIT
)))
835 tsk
->exit_state
= state
;
837 write_unlock_irq(&tasklist_lock
);
839 list_for_each_safe(_p
, _n
, &ptrace_dead
) {
841 t
= list_entry(_p
, struct task_struct
, ptrace_list
);
845 /* If the process is dead, release it - nobody will wait for it */
846 if (state
== EXIT_DEAD
)
850 fastcall NORET_TYPE
void do_exit(long code
)
852 struct task_struct
*tsk
= current
;
853 struct taskstats
*tidstats
;
857 profile_task_exit(tsk
);
859 WARN_ON(atomic_read(&tsk
->fs_excl
));
861 if (unlikely(in_interrupt()))
862 panic("Aiee, killing interrupt handler!");
863 if (unlikely(!tsk
->pid
))
864 panic("Attempted to kill the idle task!");
865 if (unlikely(tsk
== child_reaper
))
866 panic("Attempted to kill init!");
868 if (unlikely(current
->ptrace
& PT_TRACE_EXIT
)) {
869 current
->ptrace_message
= code
;
870 ptrace_notify((PTRACE_EVENT_EXIT
<< 8) | SIGTRAP
);
874 * We're taking recursive faults here in do_exit. Safest is to just
875 * leave this task alone and wait for reboot.
877 if (unlikely(tsk
->flags
& PF_EXITING
)) {
879 "Fixing recursive fault but reboot is needed!\n");
882 set_current_state(TASK_UNINTERRUPTIBLE
);
886 tsk
->flags
|= PF_EXITING
;
888 if (unlikely(in_atomic()))
889 printk(KERN_INFO
"note: %s[%d] exited with preempt_count %d\n",
890 current
->comm
, current
->pid
,
893 taskstats_exit_alloc(&tidstats
, &mycpu
);
895 acct_update_integrals(tsk
);
897 update_hiwater_rss(tsk
->mm
);
898 update_hiwater_vm(tsk
->mm
);
900 group_dead
= atomic_dec_and_test(&tsk
->signal
->live
);
902 hrtimer_cancel(&tsk
->signal
->real_timer
);
903 exit_itimers(tsk
->signal
);
905 acct_collect(code
, group_dead
);
906 if (unlikely(tsk
->robust_list
))
907 exit_robust_list(tsk
);
908 #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)
909 if (unlikely(tsk
->compat_robust_list
))
910 compat_exit_robust_list(tsk
);
912 if (unlikely(tsk
->audit_context
))
914 taskstats_exit_send(tsk
, tidstats
, group_dead
, mycpu
);
915 taskstats_exit_free(tidstats
);
928 if (group_dead
&& tsk
->signal
->leader
)
929 disassociate_ctty(1);
931 module_put(task_thread_info(tsk
)->exec_domain
->module
);
933 module_put(tsk
->binfmt
->module
);
935 tsk
->exit_code
= code
;
936 proc_exit_connector(tsk
);
938 exit_task_namespaces(tsk
);
940 mpol_free(tsk
->mempolicy
);
941 tsk
->mempolicy
= NULL
;
944 * This must happen late, after the PID is not
947 if (unlikely(!list_empty(&tsk
->pi_state_list
)))
948 exit_pi_state_list(tsk
);
949 if (unlikely(current
->pi_state_cache
))
950 kfree(current
->pi_state_cache
);
952 * Make sure we are holding no locks:
954 debug_check_no_locks_held(tsk
);
959 if (tsk
->splice_pipe
)
960 __free_pipe_info(tsk
->splice_pipe
);
963 /* causes final put_task_struct in finish_task_switch(). */
964 tsk
->state
= TASK_DEAD
;
968 /* Avoid "noreturn function does return". */
970 cpu_relax(); /* For when BUG is null */
973 EXPORT_SYMBOL_GPL(do_exit
);
975 NORET_TYPE
void complete_and_exit(struct completion
*comp
, long code
)
983 EXPORT_SYMBOL(complete_and_exit
);
985 asmlinkage
long sys_exit(int error_code
)
987 do_exit((error_code
&0xff)<<8);
991 * Take down every thread in the group. This is called by fatal signals
992 * as well as by sys_exit_group (below).
995 do_group_exit(int exit_code
)
997 BUG_ON(exit_code
& 0x80); /* core dumps don't get here */
999 if (current
->signal
->flags
& SIGNAL_GROUP_EXIT
)
1000 exit_code
= current
->signal
->group_exit_code
;
1001 else if (!thread_group_empty(current
)) {
1002 struct signal_struct
*const sig
= current
->signal
;
1003 struct sighand_struct
*const sighand
= current
->sighand
;
1004 spin_lock_irq(&sighand
->siglock
);
1005 if (sig
->flags
& SIGNAL_GROUP_EXIT
)
1006 /* Another thread got here before we took the lock. */
1007 exit_code
= sig
->group_exit_code
;
1009 sig
->group_exit_code
= exit_code
;
1010 zap_other_threads(current
);
1012 spin_unlock_irq(&sighand
->siglock
);
1020 * this kills every thread in the thread group. Note that any externally
1021 * wait4()-ing process will get the correct exit code - even if this
1022 * thread is not the thread group leader.
1024 asmlinkage
void sys_exit_group(int error_code
)
1026 do_group_exit((error_code
& 0xff) << 8);
1029 static int eligible_child(pid_t pid
, int options
, struct task_struct
*p
)
1035 if (process_group(p
) != process_group(current
))
1037 } else if (pid
!= -1) {
1038 if (process_group(p
) != -pid
)
1043 * Do not consider detached threads that are
1046 if (p
->exit_signal
== -1 && !p
->ptrace
)
1049 /* Wait for all children (clone and not) if __WALL is set;
1050 * otherwise, wait for clone children *only* if __WCLONE is
1051 * set; otherwise, wait for non-clone children *only*. (Note:
1052 * A "clone" child here is one that reports to its parent
1053 * using a signal other than SIGCHLD.) */
1054 if (((p
->exit_signal
!= SIGCHLD
) ^ ((options
& __WCLONE
) != 0))
1055 && !(options
& __WALL
))
1058 * Do not consider thread group leaders that are
1059 * in a non-empty thread group:
1061 if (delay_group_leader(p
))
1064 if (security_task_wait(p
))
1070 static int wait_noreap_copyout(struct task_struct
*p
, pid_t pid
, uid_t uid
,
1071 int why
, int status
,
1072 struct siginfo __user
*infop
,
1073 struct rusage __user
*rusagep
)
1075 int retval
= rusagep
? getrusage(p
, RUSAGE_BOTH
, rusagep
) : 0;
1079 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1081 retval
= put_user(0, &infop
->si_errno
);
1083 retval
= put_user((short)why
, &infop
->si_code
);
1085 retval
= put_user(pid
, &infop
->si_pid
);
1087 retval
= put_user(uid
, &infop
->si_uid
);
1089 retval
= put_user(status
, &infop
->si_status
);
1096 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1097 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1098 * the lock and this task is uninteresting. If we return nonzero, we have
1099 * released the lock and the system call should return.
1101 static int wait_task_zombie(struct task_struct
*p
, int noreap
,
1102 struct siginfo __user
*infop
,
1103 int __user
*stat_addr
, struct rusage __user
*ru
)
1105 unsigned long state
;
1109 if (unlikely(noreap
)) {
1112 int exit_code
= p
->exit_code
;
1115 if (unlikely(p
->exit_state
!= EXIT_ZOMBIE
))
1117 if (unlikely(p
->exit_signal
== -1 && p
->ptrace
== 0))
1120 read_unlock(&tasklist_lock
);
1121 if ((exit_code
& 0x7f) == 0) {
1123 status
= exit_code
>> 8;
1125 why
= (exit_code
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
1126 status
= exit_code
& 0x7f;
1128 return wait_noreap_copyout(p
, pid
, uid
, why
,
1133 * Try to move the task's state to DEAD
1134 * only one thread is allowed to do this:
1136 state
= xchg(&p
->exit_state
, EXIT_DEAD
);
1137 if (state
!= EXIT_ZOMBIE
) {
1138 BUG_ON(state
!= EXIT_DEAD
);
1141 if (unlikely(p
->exit_signal
== -1 && p
->ptrace
== 0)) {
1143 * This can only happen in a race with a ptraced thread
1144 * dying on another processor.
1149 if (likely(p
->real_parent
== p
->parent
) && likely(p
->signal
)) {
1150 struct signal_struct
*psig
;
1151 struct signal_struct
*sig
;
1154 * The resource counters for the group leader are in its
1155 * own task_struct. Those for dead threads in the group
1156 * are in its signal_struct, as are those for the child
1157 * processes it has previously reaped. All these
1158 * accumulate in the parent's signal_struct c* fields.
1160 * We don't bother to take a lock here to protect these
1161 * p->signal fields, because they are only touched by
1162 * __exit_signal, which runs with tasklist_lock
1163 * write-locked anyway, and so is excluded here. We do
1164 * need to protect the access to p->parent->signal fields,
1165 * as other threads in the parent group can be right
1166 * here reaping other children at the same time.
1168 spin_lock_irq(&p
->parent
->sighand
->siglock
);
1169 psig
= p
->parent
->signal
;
1172 cputime_add(psig
->cutime
,
1173 cputime_add(p
->utime
,
1174 cputime_add(sig
->utime
,
1177 cputime_add(psig
->cstime
,
1178 cputime_add(p
->stime
,
1179 cputime_add(sig
->stime
,
1182 p
->min_flt
+ sig
->min_flt
+ sig
->cmin_flt
;
1184 p
->maj_flt
+ sig
->maj_flt
+ sig
->cmaj_flt
;
1186 p
->nvcsw
+ sig
->nvcsw
+ sig
->cnvcsw
;
1188 p
->nivcsw
+ sig
->nivcsw
+ sig
->cnivcsw
;
1189 spin_unlock_irq(&p
->parent
->sighand
->siglock
);
1193 * Now we are sure this task is interesting, and no other
1194 * thread can reap it because we set its state to EXIT_DEAD.
1196 read_unlock(&tasklist_lock
);
1198 retval
= ru
? getrusage(p
, RUSAGE_BOTH
, ru
) : 0;
1199 status
= (p
->signal
->flags
& SIGNAL_GROUP_EXIT
)
1200 ? p
->signal
->group_exit_code
: p
->exit_code
;
1201 if (!retval
&& stat_addr
)
1202 retval
= put_user(status
, stat_addr
);
1203 if (!retval
&& infop
)
1204 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1205 if (!retval
&& infop
)
1206 retval
= put_user(0, &infop
->si_errno
);
1207 if (!retval
&& infop
) {
1210 if ((status
& 0x7f) == 0) {
1214 why
= (status
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
1217 retval
= put_user((short)why
, &infop
->si_code
);
1219 retval
= put_user(status
, &infop
->si_status
);
1221 if (!retval
&& infop
)
1222 retval
= put_user(p
->pid
, &infop
->si_pid
);
1223 if (!retval
&& infop
)
1224 retval
= put_user(p
->uid
, &infop
->si_uid
);
1226 // TODO: is this safe?
1227 p
->exit_state
= EXIT_ZOMBIE
;
1231 if (p
->real_parent
!= p
->parent
) {
1232 write_lock_irq(&tasklist_lock
);
1233 /* Double-check with lock held. */
1234 if (p
->real_parent
!= p
->parent
) {
1236 // TODO: is this safe?
1237 p
->exit_state
= EXIT_ZOMBIE
;
1239 * If this is not a detached task, notify the parent.
1240 * If it's still not detached after that, don't release
1243 if (p
->exit_signal
!= -1) {
1244 do_notify_parent(p
, p
->exit_signal
);
1245 if (p
->exit_signal
!= -1)
1249 write_unlock_irq(&tasklist_lock
);
1258 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1259 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1260 * the lock and this task is uninteresting. If we return nonzero, we have
1261 * released the lock and the system call should return.
1263 static int wait_task_stopped(struct task_struct
*p
, int delayed_group_leader
,
1264 int noreap
, struct siginfo __user
*infop
,
1265 int __user
*stat_addr
, struct rusage __user
*ru
)
1267 int retval
, exit_code
;
1271 if (delayed_group_leader
&& !(p
->ptrace
& PT_PTRACED
) &&
1272 p
->signal
&& p
->signal
->group_stop_count
> 0)
1274 * A group stop is in progress and this is the group leader.
1275 * We won't report until all threads have stopped.
1280 * Now we are pretty sure this task is interesting.
1281 * Make sure it doesn't get reaped out from under us while we
1282 * give up the lock and then examine it below. We don't want to
1283 * keep holding onto the tasklist_lock while we call getrusage and
1284 * possibly take page faults for user memory.
1287 read_unlock(&tasklist_lock
);
1289 if (unlikely(noreap
)) {
1292 int why
= (p
->ptrace
& PT_PTRACED
) ? CLD_TRAPPED
: CLD_STOPPED
;
1294 exit_code
= p
->exit_code
;
1295 if (unlikely(!exit_code
) ||
1296 unlikely(p
->state
& TASK_TRACED
))
1298 return wait_noreap_copyout(p
, pid
, uid
,
1299 why
, (exit_code
<< 8) | 0x7f,
1303 write_lock_irq(&tasklist_lock
);
1306 * This uses xchg to be atomic with the thread resuming and setting
1307 * it. It must also be done with the write lock held to prevent a
1308 * race with the EXIT_ZOMBIE case.
1310 exit_code
= xchg(&p
->exit_code
, 0);
1311 if (unlikely(p
->exit_state
)) {
1313 * The task resumed and then died. Let the next iteration
1314 * catch it in EXIT_ZOMBIE. Note that exit_code might
1315 * already be zero here if it resumed and did _exit(0).
1316 * The task itself is dead and won't touch exit_code again;
1317 * other processors in this function are locked out.
1319 p
->exit_code
= exit_code
;
1322 if (unlikely(exit_code
== 0)) {
1324 * Another thread in this function got to it first, or it
1325 * resumed, or it resumed and then died.
1327 write_unlock_irq(&tasklist_lock
);
1331 * We are returning to the wait loop without having successfully
1332 * removed the process and having released the lock. We cannot
1333 * continue, since the "p" task pointer is potentially stale.
1335 * Return -EAGAIN, and do_wait() will restart the loop from the
1336 * beginning. Do _not_ re-acquire the lock.
1341 /* move to end of parent's list to avoid starvation */
1345 write_unlock_irq(&tasklist_lock
);
1347 retval
= ru
? getrusage(p
, RUSAGE_BOTH
, ru
) : 0;
1348 if (!retval
&& stat_addr
)
1349 retval
= put_user((exit_code
<< 8) | 0x7f, stat_addr
);
1350 if (!retval
&& infop
)
1351 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1352 if (!retval
&& infop
)
1353 retval
= put_user(0, &infop
->si_errno
);
1354 if (!retval
&& infop
)
1355 retval
= put_user((short)((p
->ptrace
& PT_PTRACED
)
1356 ? CLD_TRAPPED
: CLD_STOPPED
),
1358 if (!retval
&& infop
)
1359 retval
= put_user(exit_code
, &infop
->si_status
);
1360 if (!retval
&& infop
)
1361 retval
= put_user(p
->pid
, &infop
->si_pid
);
1362 if (!retval
&& infop
)
1363 retval
= put_user(p
->uid
, &infop
->si_uid
);
1373 * Handle do_wait work for one task in a live, non-stopped state.
1374 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1375 * the lock and this task is uninteresting. If we return nonzero, we have
1376 * released the lock and the system call should return.
1378 static int wait_task_continued(struct task_struct
*p
, int noreap
,
1379 struct siginfo __user
*infop
,
1380 int __user
*stat_addr
, struct rusage __user
*ru
)
1386 if (unlikely(!p
->signal
))
1389 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
))
1392 spin_lock_irq(&p
->sighand
->siglock
);
1393 /* Re-check with the lock held. */
1394 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
)) {
1395 spin_unlock_irq(&p
->sighand
->siglock
);
1399 p
->signal
->flags
&= ~SIGNAL_STOP_CONTINUED
;
1400 spin_unlock_irq(&p
->sighand
->siglock
);
1405 read_unlock(&tasklist_lock
);
1408 retval
= ru
? getrusage(p
, RUSAGE_BOTH
, ru
) : 0;
1410 if (!retval
&& stat_addr
)
1411 retval
= put_user(0xffff, stat_addr
);
1415 retval
= wait_noreap_copyout(p
, pid
, uid
,
1416 CLD_CONTINUED
, SIGCONT
,
1418 BUG_ON(retval
== 0);
1425 static inline int my_ptrace_child(struct task_struct
*p
)
1427 if (!(p
->ptrace
& PT_PTRACED
))
1429 if (!(p
->ptrace
& PT_ATTACHED
))
1432 * This child was PTRACE_ATTACH'd. We should be seeing it only if
1433 * we are the attacher. If we are the real parent, this is a race
1434 * inside ptrace_attach. It is waiting for the tasklist_lock,
1435 * which we have to switch the parent links, but has already set
1436 * the flags in p->ptrace.
1438 return (p
->parent
!= p
->real_parent
);
1441 static long do_wait(pid_t pid
, int options
, struct siginfo __user
*infop
,
1442 int __user
*stat_addr
, struct rusage __user
*ru
)
1444 DECLARE_WAITQUEUE(wait
, current
);
1445 struct task_struct
*tsk
;
1448 add_wait_queue(¤t
->signal
->wait_chldexit
,&wait
);
1451 * We will set this flag if we see any child that might later
1452 * match our criteria, even if we are not able to reap it yet.
1455 current
->state
= TASK_INTERRUPTIBLE
;
1456 read_lock(&tasklist_lock
);
1459 struct task_struct
*p
;
1460 struct list_head
*_p
;
1463 list_for_each(_p
,&tsk
->children
) {
1464 p
= list_entry(_p
, struct task_struct
, sibling
);
1466 ret
= eligible_child(pid
, options
, p
);
1473 * When we hit the race with PTRACE_ATTACH,
1474 * we will not report this child. But the
1475 * race means it has not yet been moved to
1476 * our ptrace_children list, so we need to
1477 * set the flag here to avoid a spurious ECHILD
1478 * when the race happens with the only child.
1481 if (!my_ptrace_child(p
))
1486 * It's stopped now, so it might later
1487 * continue, exit, or stop again.
1490 if (!(options
& WUNTRACED
) &&
1491 !my_ptrace_child(p
))
1493 retval
= wait_task_stopped(p
, ret
== 2,
1494 (options
& WNOWAIT
),
1497 if (retval
== -EAGAIN
)
1499 if (retval
!= 0) /* He released the lock. */
1504 if (p
->exit_state
== EXIT_DEAD
)
1506 // case EXIT_ZOMBIE:
1507 if (p
->exit_state
== EXIT_ZOMBIE
) {
1509 * Eligible but we cannot release
1513 goto check_continued
;
1514 if (!likely(options
& WEXITED
))
1516 retval
= wait_task_zombie(
1517 p
, (options
& WNOWAIT
),
1518 infop
, stat_addr
, ru
);
1519 /* He released the lock. */
1526 * It's running now, so it might later
1527 * exit, stop, or stop and then continue.
1530 if (!unlikely(options
& WCONTINUED
))
1532 retval
= wait_task_continued(
1533 p
, (options
& WNOWAIT
),
1534 infop
, stat_addr
, ru
);
1535 if (retval
!= 0) /* He released the lock. */
1541 list_for_each(_p
, &tsk
->ptrace_children
) {
1542 p
= list_entry(_p
, struct task_struct
,
1544 if (!eligible_child(pid
, options
, p
))
1550 if (options
& __WNOTHREAD
)
1552 tsk
= next_thread(tsk
);
1553 BUG_ON(tsk
->signal
!= current
->signal
);
1554 } while (tsk
!= current
);
1556 read_unlock(&tasklist_lock
);
1559 if (options
& WNOHANG
)
1561 retval
= -ERESTARTSYS
;
1562 if (signal_pending(current
))
1569 current
->state
= TASK_RUNNING
;
1570 remove_wait_queue(¤t
->signal
->wait_chldexit
,&wait
);
1576 * For a WNOHANG return, clear out all the fields
1577 * we would set so the user can easily tell the
1581 retval
= put_user(0, &infop
->si_signo
);
1583 retval
= put_user(0, &infop
->si_errno
);
1585 retval
= put_user(0, &infop
->si_code
);
1587 retval
= put_user(0, &infop
->si_pid
);
1589 retval
= put_user(0, &infop
->si_uid
);
1591 retval
= put_user(0, &infop
->si_status
);
1597 asmlinkage
long sys_waitid(int which
, pid_t pid
,
1598 struct siginfo __user
*infop
, int options
,
1599 struct rusage __user
*ru
)
1603 if (options
& ~(WNOHANG
|WNOWAIT
|WEXITED
|WSTOPPED
|WCONTINUED
))
1605 if (!(options
& (WEXITED
|WSTOPPED
|WCONTINUED
)))
1625 ret
= do_wait(pid
, options
, infop
, NULL
, ru
);
1627 /* avoid REGPARM breakage on x86: */
1628 prevent_tail_call(ret
);
1632 asmlinkage
long sys_wait4(pid_t pid
, int __user
*stat_addr
,
1633 int options
, struct rusage __user
*ru
)
1637 if (options
& ~(WNOHANG
|WUNTRACED
|WCONTINUED
|
1638 __WNOTHREAD
|__WCLONE
|__WALL
))
1640 ret
= do_wait(pid
, options
| WEXITED
, NULL
, stat_addr
, ru
);
1642 /* avoid REGPARM breakage on x86: */
1643 prevent_tail_call(ret
);
1647 #ifdef __ARCH_WANT_SYS_WAITPID
1650 * sys_waitpid() remains for compatibility. waitpid() should be
1651 * implemented by calling sys_wait4() from libc.a.
1653 asmlinkage
long sys_waitpid(pid_t pid
, int __user
*stat_addr
, int options
)
1655 return sys_wait4(pid
, stat_addr
, options
, NULL
);
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