4 * Copyright (C) 1991, 1992 Linus Torvalds
7 #include <linux/config.h>
9 #include <linux/slab.h>
10 #include <linux/interrupt.h>
11 #include <linux/smp_lock.h>
12 #include <linux/module.h>
13 #include <linux/completion.h>
14 #include <linux/personality.h>
15 #include <linux/tty.h>
16 #include <linux/namespace.h>
17 #include <linux/security.h>
18 #include <linux/acct.h>
19 #include <linux/file.h>
20 #include <linux/binfmts.h>
21 #include <linux/ptrace.h>
22 #include <linux/profile.h>
23 #include <linux/mount.h>
24 #include <linux/proc_fs.h>
26 #include <asm/uaccess.h>
27 #include <asm/pgtable.h>
28 #include <asm/mmu_context.h>
30 extern void sem_exit (void);
31 extern struct task_struct
*child_reaper
;
33 int getrusage(struct task_struct
*, int, struct rusage
*);
35 static void __unhash_process(struct task_struct
*p
)
38 detach_pid(p
, PIDTYPE_PID
);
39 detach_pid(p
, PIDTYPE_TGID
);
40 if (thread_group_leader(p
)) {
41 detach_pid(p
, PIDTYPE_PGID
);
42 detach_pid(p
, PIDTYPE_SID
);
44 __get_cpu_var(process_counts
)--;
50 void release_task(struct task_struct
* p
)
53 struct dentry
*proc_dentry
;
55 BUG_ON(p
->state
< TASK_ZOMBIE
);
57 atomic_dec(&p
->user
->processes
);
58 spin_lock(&p
->proc_lock
);
59 proc_dentry
= proc_pid_unhash(p
);
60 write_lock_irq(&tasklist_lock
);
61 if (unlikely(p
->ptrace
))
63 BUG_ON(!list_empty(&p
->ptrace_list
) || !list_empty(&p
->ptrace_children
));
69 * If we are the last non-leader member of the thread
70 * group, and the leader is zombie, then notify the
71 * group leader's parent process. (if it wants notification.)
73 leader
= p
->group_leader
;
74 if (leader
!= p
&& thread_group_empty(leader
) &&
75 leader
->state
== TASK_ZOMBIE
&& leader
->exit_signal
!= -1)
76 do_notify_parent(leader
, leader
->exit_signal
);
78 p
->parent
->cutime
+= p
->utime
+ p
->cutime
;
79 p
->parent
->cstime
+= p
->stime
+ p
->cstime
;
80 p
->parent
->cmin_flt
+= p
->min_flt
+ p
->cmin_flt
;
81 p
->parent
->cmaj_flt
+= p
->maj_flt
+ p
->cmaj_flt
;
82 p
->parent
->cnswap
+= p
->nswap
+ p
->cnswap
;
83 p
->parent
->cnvcsw
+= p
->nvcsw
+ p
->cnvcsw
;
84 p
->parent
->cnivcsw
+= p
->nivcsw
+ p
->cnivcsw
;
86 write_unlock_irq(&tasklist_lock
);
87 spin_unlock(&p
->proc_lock
);
88 proc_pid_flush(proc_dentry
);
93 /* we are using it only for SMP init */
95 void unhash_process(struct task_struct
*p
)
97 struct dentry
*proc_dentry
;
99 spin_lock(&p
->proc_lock
);
100 proc_dentry
= proc_pid_unhash(p
);
101 write_lock_irq(&tasklist_lock
);
103 write_unlock_irq(&tasklist_lock
);
104 spin_unlock(&p
->proc_lock
);
105 proc_pid_flush(proc_dentry
);
109 * This checks not only the pgrp, but falls back on the pid if no
110 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
113 int session_of_pgrp(int pgrp
)
115 struct task_struct
*p
;
120 read_lock(&tasklist_lock
);
121 for_each_task_pid(pgrp
, PIDTYPE_PGID
, p
, l
, pid
)
122 if (p
->session
> 0) {
126 p
= find_task_by_pid(pgrp
);
130 read_unlock(&tasklist_lock
);
136 * Determine if a process group is "orphaned", according to the POSIX
137 * definition in 2.2.2.52. Orphaned process groups are not to be affected
138 * by terminal-generated stop signals. Newly orphaned process groups are
139 * to receive a SIGHUP and a SIGCONT.
141 * "I ask you, have you ever known what it is to be an orphan?"
143 static int will_become_orphaned_pgrp(int pgrp
, task_t
*ignored_task
)
145 struct task_struct
*p
;
150 for_each_task_pid(pgrp
, PIDTYPE_PGID
, p
, l
, pid
) {
151 if (p
== ignored_task
152 || p
->state
>= TASK_ZOMBIE
153 || p
->real_parent
->pid
== 1)
155 if (p
->real_parent
->pgrp
!= pgrp
156 && p
->real_parent
->session
== p
->session
) {
161 return ret
; /* (sighing) "Often!" */
164 int is_orphaned_pgrp(int pgrp
)
168 read_lock(&tasklist_lock
);
169 retval
= will_become_orphaned_pgrp(pgrp
, NULL
);
170 read_unlock(&tasklist_lock
);
175 static inline int has_stopped_jobs(int pgrp
)
178 struct task_struct
*p
;
182 for_each_task_pid(pgrp
, PIDTYPE_PGID
, p
, l
, pid
) {
183 if (p
->state
!= TASK_STOPPED
)
186 /* If p is stopped by a debugger on a signal that won't
187 stop it, then don't count p as stopped. This isn't
188 perfect but it's a good approximation. */
189 if (unlikely (p
->ptrace
)
190 && p
->exit_code
!= SIGSTOP
191 && p
->exit_code
!= SIGTSTP
192 && p
->exit_code
!= SIGTTOU
193 && p
->exit_code
!= SIGTTIN
)
203 * reparent_to_init() - Reparent the calling kernel thread to the init task.
205 * If a kernel thread is launched as a result of a system call, or if
206 * it ever exits, it should generally reparent itself to init so that
207 * it is correctly cleaned up on exit.
209 * The various task state such as scheduling policy and priority may have
210 * been inherited from a user process, so we reset them to sane values here.
212 * NOTE that reparent_to_init() gives the caller full capabilities.
214 void reparent_to_init(void)
216 write_lock_irq(&tasklist_lock
);
218 ptrace_unlink(current
);
219 /* Reparent to init */
220 REMOVE_LINKS(current
);
221 current
->parent
= child_reaper
;
222 current
->real_parent
= child_reaper
;
225 /* Set the exit signal to SIGCHLD so we signal init on exit */
226 current
->exit_signal
= SIGCHLD
;
228 if ((current
->policy
== SCHED_NORMAL
) && (task_nice(current
) < 0))
229 set_user_nice(current
, 0);
233 security_task_reparent_to_init(current
);
234 memcpy(current
->rlim
, init_task
.rlim
, sizeof(*(current
->rlim
)));
235 atomic_inc(&(INIT_USER
->__count
));
236 switch_uid(INIT_USER
);
238 write_unlock_irq(&tasklist_lock
);
241 void __set_special_pids(pid_t session
, pid_t pgrp
)
243 struct task_struct
*curr
= current
;
245 if (curr
->session
!= session
) {
246 detach_pid(curr
, PIDTYPE_SID
);
247 curr
->session
= session
;
248 attach_pid(curr
, PIDTYPE_SID
, session
);
250 if (curr
->pgrp
!= pgrp
) {
251 detach_pid(curr
, PIDTYPE_PGID
);
253 attach_pid(curr
, PIDTYPE_PGID
, pgrp
);
257 void set_special_pids(pid_t session
, pid_t pgrp
)
259 write_lock_irq(&tasklist_lock
);
260 __set_special_pids(session
, pgrp
);
261 write_unlock_irq(&tasklist_lock
);
265 * Let kernel threads use this to say that they
266 * allow a certain signal (since daemonize() will
267 * have disabled all of them by default).
269 int allow_signal(int sig
)
271 if (sig
< 1 || sig
> _NSIG
)
274 spin_lock_irq(¤t
->sighand
->siglock
);
275 sigdelset(¤t
->blocked
, sig
);
277 spin_unlock_irq(¤t
->sighand
->siglock
);
281 EXPORT_SYMBOL(allow_signal
);
284 * Put all the gunge required to become a kernel thread without
285 * attached user resources in one place where it belongs.
288 void daemonize(const char *name
, ...)
291 struct fs_struct
*fs
;
294 va_start(args
, name
);
295 vsnprintf(current
->comm
, sizeof(current
->comm
), name
, args
);
299 * If we were started as result of loading a module, close all of the
300 * user space pages. We don't need them, and if we didn't close them
301 * they would be locked into memory.
305 set_special_pids(1, 1);
308 /* Block and flush all signals */
309 sigfillset(&blocked
);
310 sigprocmask(SIG_BLOCK
, &blocked
, NULL
);
311 flush_signals(current
);
313 /* Become as one with the init task */
315 exit_fs(current
); /* current->fs->count--; */
318 atomic_inc(&fs
->count
);
320 current
->files
= init_task
.files
;
321 atomic_inc(¤t
->files
->count
);
326 static inline void close_files(struct files_struct
* files
)
334 if (i
>= files
->max_fdset
|| i
>= files
->max_fds
)
336 set
= files
->open_fds
->fds_bits
[j
++];
339 struct file
* file
= xchg(&files
->fd
[i
], NULL
);
341 filp_close(file
, files
);
349 void put_files_struct(struct files_struct
*files
)
351 if (atomic_dec_and_test(&files
->count
)) {
354 * Free the fd and fdset arrays if we expanded them.
356 if (files
->fd
!= &files
->fd_array
[0])
357 free_fd_array(files
->fd
, files
->max_fds
);
358 if (files
->max_fdset
> __FD_SETSIZE
) {
359 free_fdset(files
->open_fds
, files
->max_fdset
);
360 free_fdset(files
->close_on_exec
, files
->max_fdset
);
362 kmem_cache_free(files_cachep
, files
);
366 static inline void __exit_files(struct task_struct
*tsk
)
368 struct files_struct
* files
= tsk
->files
;
374 put_files_struct(files
);
378 void exit_files(struct task_struct
*tsk
)
383 static inline void __put_fs_struct(struct fs_struct
*fs
)
385 /* No need to hold fs->lock if we are killing it */
386 if (atomic_dec_and_test(&fs
->count
)) {
393 mntput(fs
->altrootmnt
);
395 kmem_cache_free(fs_cachep
, fs
);
399 void put_fs_struct(struct fs_struct
*fs
)
404 static inline void __exit_fs(struct task_struct
*tsk
)
406 struct fs_struct
* fs
= tsk
->fs
;
416 void exit_fs(struct task_struct
*tsk
)
422 * Turn us into a lazy TLB process if we
425 static inline void __exit_mm(struct task_struct
* tsk
)
427 struct mm_struct
*mm
= tsk
->mm
;
433 * Serialize with any possible pending coredump:
435 if (mm
->core_waiters
) {
436 down_write(&mm
->mmap_sem
);
437 if (!--mm
->core_waiters
)
438 complete(mm
->core_startup_done
);
439 up_write(&mm
->mmap_sem
);
441 wait_for_completion(&mm
->core_done
);
443 atomic_inc(&mm
->mm_count
);
444 if (mm
!= tsk
->active_mm
) BUG();
445 /* more a memory barrier than a real lock */
448 enter_lazy_tlb(mm
, current
);
453 void exit_mm(struct task_struct
*tsk
)
458 static inline void choose_new_parent(task_t
*p
, task_t
*reaper
, task_t
*child_reaper
)
461 * Make sure we're not reparenting to ourselves and that
462 * the parent is not a zombie.
464 if (p
== reaper
|| reaper
->state
>= TASK_ZOMBIE
)
465 p
->real_parent
= child_reaper
;
467 p
->real_parent
= reaper
;
468 if (p
->parent
== p
->real_parent
)
472 static inline void reparent_thread(task_t
*p
, task_t
*father
, int traced
)
474 /* We don't want people slaying init. */
475 if (p
->exit_signal
!= -1)
476 p
->exit_signal
= SIGCHLD
;
479 if (p
->pdeath_signal
)
480 send_group_sig_info(p
->pdeath_signal
, 0, p
);
482 /* Move the child from its dying parent to the new one. */
483 if (unlikely(traced
)) {
484 /* Preserve ptrace links if someone else is tracing this child. */
485 list_del_init(&p
->ptrace_list
);
486 if (p
->parent
!= p
->real_parent
)
487 list_add(&p
->ptrace_list
, &p
->real_parent
->ptrace_children
);
489 /* If this child is being traced, then we're the one tracing it
490 * anyway, so let go of it.
493 list_del_init(&p
->sibling
);
494 p
->parent
= p
->real_parent
;
495 list_add_tail(&p
->sibling
, &p
->parent
->children
);
497 /* If we'd notified the old parent about this child's death,
498 * also notify the new parent.
500 if (p
->state
== TASK_ZOMBIE
&& p
->exit_signal
!= -1 &&
501 thread_group_empty(p
))
502 do_notify_parent(p
, p
->exit_signal
);
506 * process group orphan check
507 * Case ii: Our child is in a different pgrp
508 * than we are, and it was the only connection
509 * outside, so the child pgrp is now orphaned.
511 if ((p
->pgrp
!= father
->pgrp
) &&
512 (p
->session
== father
->session
)) {
515 if (will_become_orphaned_pgrp(pgrp
, NULL
) && has_stopped_jobs(pgrp
)) {
516 __kill_pg_info(SIGHUP
, (void *)1, pgrp
);
517 __kill_pg_info(SIGCONT
, (void *)1, pgrp
);
523 * When we die, we re-parent all our children.
524 * Try to give them to another thread in our thread
525 * group, and if no such member exists, give it to
526 * the global child reaper process (ie "init")
528 static inline void forget_original_parent(struct task_struct
* father
)
530 struct task_struct
*p
, *reaper
= father
;
531 struct list_head
*_p
, *_n
;
533 reaper
= father
->group_leader
;
534 if (reaper
== father
)
535 reaper
= child_reaper
;
538 * There are only two places where our children can be:
540 * - in our child list
541 * - in our ptraced child list
543 * Search them and reparent children.
545 list_for_each_safe(_p
, _n
, &father
->children
) {
546 p
= list_entry(_p
,struct task_struct
,sibling
);
547 if (father
== p
->real_parent
) {
548 choose_new_parent(p
, reaper
, child_reaper
);
549 reparent_thread(p
, father
, 0);
552 if (p
->state
== TASK_ZOMBIE
&& p
->exit_signal
!= -1 &&
553 thread_group_empty(p
))
554 do_notify_parent(p
, p
->exit_signal
);
557 list_for_each_safe(_p
, _n
, &father
->ptrace_children
) {
558 p
= list_entry(_p
,struct task_struct
,ptrace_list
);
559 choose_new_parent(p
, reaper
, child_reaper
);
560 reparent_thread(p
, father
, 1);
565 * Send signals to all our closest relatives so that they know
566 * to properly mourn us..
568 static void exit_notify(struct task_struct
*tsk
)
570 struct task_struct
*t
;
572 if (signal_pending(tsk
) && !tsk
->signal
->group_exit
573 && !thread_group_empty(tsk
)) {
575 * This occurs when there was a race between our exit
576 * syscall and a group signal choosing us as the one to
577 * wake up. It could be that we are the only thread
578 * alerted to check for pending signals, but another thread
579 * should be woken now to take the signal since we will not.
580 * Now we'll wake all the threads in the group just to make
581 * sure someone gets all the pending signals.
583 read_lock(&tasklist_lock
);
584 spin_lock_irq(&tsk
->sighand
->siglock
);
585 for (t
= next_thread(tsk
); t
!= tsk
; t
= next_thread(t
))
586 if (!signal_pending(t
) && !(t
->flags
& PF_EXITING
)) {
587 recalc_sigpending_tsk(t
);
588 if (signal_pending(t
))
589 signal_wake_up(t
, 0);
591 spin_unlock_irq(&tsk
->sighand
->siglock
);
592 read_unlock(&tasklist_lock
);
595 write_lock_irq(&tasklist_lock
);
598 * This does two things:
600 * A. Make init inherit all the child processes
601 * B. Check to see if any process groups have become orphaned
602 * as a result of our exiting, and if they have any stopped
603 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
606 forget_original_parent(tsk
);
607 BUG_ON(!list_empty(&tsk
->children
));
610 * Check to see if any process groups have become orphaned
611 * as a result of our exiting, and if they have any stopped
612 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
614 * Case i: Our father is in a different pgrp than we are
615 * and we were the only connection outside, so our pgrp
616 * is about to become orphaned.
619 t
= tsk
->real_parent
;
621 if ((t
->pgrp
!= tsk
->pgrp
) &&
622 (t
->session
== tsk
->session
) &&
623 will_become_orphaned_pgrp(tsk
->pgrp
, tsk
) &&
624 has_stopped_jobs(tsk
->pgrp
)) {
625 __kill_pg_info(SIGHUP
, (void *)1, tsk
->pgrp
);
626 __kill_pg_info(SIGCONT
, (void *)1, tsk
->pgrp
);
629 /* Let father know we died
631 * Thread signals are configurable, but you aren't going to use
632 * that to send signals to arbitary processes.
633 * That stops right now.
635 * If the parent exec id doesn't match the exec id we saved
636 * when we started then we know the parent has changed security
639 * If our self_exec id doesn't match our parent_exec_id then
640 * we have changed execution domain as these two values started
641 * the same after a fork.
645 if (tsk
->exit_signal
!= SIGCHLD
&& tsk
->exit_signal
!= -1 &&
646 ( tsk
->parent_exec_id
!= t
->self_exec_id
||
647 tsk
->self_exec_id
!= tsk
->parent_exec_id
)
648 && !capable(CAP_KILL
))
649 tsk
->exit_signal
= SIGCHLD
;
652 /* If something other than our normal parent is ptracing us, then
653 * send it a SIGCHLD instead of honoring exit_signal. exit_signal
654 * only has special meaning to our real parent.
656 if (tsk
->exit_signal
!= -1 && thread_group_empty(tsk
)) {
657 int signal
= tsk
->parent
== tsk
->real_parent
? tsk
->exit_signal
: SIGCHLD
;
658 do_notify_parent(tsk
, signal
);
659 } else if (tsk
->ptrace
) {
660 do_notify_parent(tsk
, SIGCHLD
);
663 tsk
->state
= TASK_ZOMBIE
;
665 * In the preemption case it must be impossible for the task
666 * to get runnable again, so use "_raw_" unlock to keep
667 * preempt_count elevated until we schedule().
669 * To avoid deadlock on SMP, interrupts must be unmasked. If we
670 * don't, subsequently called functions (e.g, wait_task_inactive()
671 * via release_task()) will spin, with interrupt flags
672 * unwittingly blocked, until the other task sleeps. That task
673 * may itself be waiting for smp_call_function() to answer and
674 * complete, and with interrupts blocked that will never happen.
676 _raw_write_unlock(&tasklist_lock
);
680 NORET_TYPE
void do_exit(long code
)
682 struct task_struct
*tsk
= current
;
684 if (unlikely(in_interrupt()))
685 panic("Aiee, killing interrupt handler!");
686 if (unlikely(!tsk
->pid
))
687 panic("Attempted to kill the idle task!");
688 if (unlikely(tsk
->pid
== 1))
689 panic("Attempted to kill init!");
692 tsk
->flags
|= PF_EXITING
;
693 del_timer_sync(&tsk
->real_timer
);
695 if (unlikely(in_atomic()))
696 printk(KERN_INFO
"note: %s[%d] exited with preempt_count %d\n",
697 current
->comm
, current
->pid
,
700 profile_exit_task(tsk
);
702 if (unlikely(current
->ptrace
& PT_TRACE_EXIT
)) {
703 current
->ptrace_message
= code
;
704 ptrace_notify((PTRACE_EVENT_EXIT
<< 8) | SIGTRAP
);
718 disassociate_ctty(1);
720 module_put(tsk
->thread_info
->exec_domain
->module
);
722 module_put(tsk
->binfmt
->module
);
724 tsk
->exit_code
= code
;
727 if (tsk
->exit_signal
== -1 && tsk
->ptrace
== 0)
732 /* Avoid "noreturn function does return". */
736 NORET_TYPE
void complete_and_exit(struct completion
*comp
, long code
)
744 asmlinkage
long sys_exit(int error_code
)
746 do_exit((error_code
&0xff)<<8);
749 task_t
*next_thread(task_t
*p
)
751 struct pid_link
*link
= p
->pids
+ PIDTYPE_TGID
;
752 struct list_head
*tmp
, *head
= &link
->pidptr
->task_list
;
757 if (!spin_is_locked(&p
->sighand
->siglock
) &&
758 !rwlock_is_locked(&tasklist_lock
))
761 tmp
= link
->pid_chain
.next
;
765 return pid_task(tmp
, PIDTYPE_TGID
);
769 * Take down every thread in the group. This is called by fatal signals
770 * as well as by sys_exit_group (below).
773 do_group_exit(int exit_code
)
775 BUG_ON(exit_code
& 0x80); /* core dumps don't get here */
777 if (current
->signal
->group_exit
)
778 exit_code
= current
->signal
->group_exit_code
;
779 else if (!thread_group_empty(current
)) {
780 struct signal_struct
*const sig
= current
->signal
;
781 struct sighand_struct
*const sighand
= current
->sighand
;
782 read_lock(&tasklist_lock
);
783 spin_lock_irq(&sighand
->siglock
);
785 /* Another thread got here before we took the lock. */
786 exit_code
= sig
->group_exit_code
;
789 sig
->group_exit_code
= exit_code
;
790 zap_other_threads(current
);
792 spin_unlock_irq(&sighand
->siglock
);
793 read_unlock(&tasklist_lock
);
801 * this kills every thread in the thread group. Note that any externally
802 * wait4()-ing process will get the correct exit code - even if this
803 * thread is not the thread group leader.
805 asmlinkage
void sys_exit_group(int error_code
)
807 do_group_exit((error_code
& 0xff) << 8);
810 static int eligible_child(pid_t pid
, int options
, task_t
*p
)
816 if (p
->pgrp
!= current
->pgrp
)
818 } else if (pid
!= -1) {
824 * Do not consider detached threads that are
827 if (p
->exit_signal
== -1 && !p
->ptrace
)
830 /* Wait for all children (clone and not) if __WALL is set;
831 * otherwise, wait for clone children *only* if __WCLONE is
832 * set; otherwise, wait for non-clone children *only*. (Note:
833 * A "clone" child here is one that reports to its parent
834 * using a signal other than SIGCHLD.) */
835 if (((p
->exit_signal
!= SIGCHLD
) ^ ((options
& __WCLONE
) != 0))
836 && !(options
& __WALL
))
839 * Do not consider thread group leaders that are
840 * in a non-empty thread group:
842 if (current
->tgid
!= p
->tgid
&& delay_group_leader(p
))
845 if (security_task_wait(p
))
852 * Handle sys_wait4 work for one task in state TASK_ZOMBIE. We hold
853 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
854 * the lock and this task is uninteresting. If we return nonzero, we have
855 * released the lock and the system call should return.
857 static int wait_task_zombie(task_t
*p
, unsigned int *stat_addr
, struct rusage
*ru
)
863 * Try to move the task's state to DEAD
864 * only one thread is allowed to do this:
866 state
= xchg(&p
->state
, TASK_DEAD
);
867 if (state
!= TASK_ZOMBIE
) {
868 BUG_ON(state
!= TASK_DEAD
);
871 if (unlikely(p
->exit_signal
== -1 && p
->ptrace
== 0))
873 * This can only happen in a race with a ptraced thread
874 * dying on another processor.
879 * Now we are sure this task is interesting, and no other
880 * thread can reap it because we set its state to TASK_DEAD.
882 read_unlock(&tasklist_lock
);
884 retval
= ru
? getrusage(p
, RUSAGE_BOTH
, ru
) : 0;
885 if (!retval
&& stat_addr
) {
886 if (p
->signal
->group_exit
)
887 retval
= put_user(p
->signal
->group_exit_code
, stat_addr
);
889 retval
= put_user(p
->exit_code
, stat_addr
);
892 p
->state
= TASK_ZOMBIE
;
896 if (p
->real_parent
!= p
->parent
) {
897 write_lock_irq(&tasklist_lock
);
898 /* Double-check with lock held. */
899 if (p
->real_parent
!= p
->parent
) {
901 p
->state
= TASK_ZOMBIE
;
902 /* If this is a detached thread, this is where it goes away. */
903 if (p
->exit_signal
== -1) {
904 /* release_task takes the lock itself. */
905 write_unlock_irq(&tasklist_lock
);
909 do_notify_parent(p
, p
->exit_signal
);
910 write_unlock_irq(&tasklist_lock
);
915 write_unlock_irq(&tasklist_lock
);
924 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
925 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
926 * the lock and this task is uninteresting. If we return nonzero, we have
927 * released the lock and the system call should return.
929 static int wait_task_stopped(task_t
*p
, int delayed_group_leader
,
930 unsigned int *stat_addr
, struct rusage
*ru
)
932 int retval
, exit_code
;
936 if (delayed_group_leader
&& !(p
->ptrace
& PT_PTRACED
) &&
937 p
->signal
&& p
->signal
->group_stop_count
> 0)
939 * A group stop is in progress and this is the group leader.
940 * We won't report until all threads have stopped.
945 * Now we are pretty sure this task is interesting.
946 * Make sure it doesn't get reaped out from under us while we
947 * give up the lock and then examine it below. We don't want to
948 * keep holding onto the tasklist_lock while we call getrusage and
949 * possibly take page faults for user memory.
952 read_unlock(&tasklist_lock
);
953 write_lock_irq(&tasklist_lock
);
956 * This uses xchg to be atomic with the thread resuming and setting
957 * it. It must also be done with the write lock held to prevent a
958 * race with the TASK_ZOMBIE case.
960 exit_code
= xchg(&p
->exit_code
, 0);
961 if (unlikely(p
->state
> TASK_STOPPED
)) {
963 * The task resumed and then died. Let the next iteration
964 * catch it in TASK_ZOMBIE. Note that exit_code might
965 * already be zero here if it resumed and did _exit(0).
966 * The task itself is dead and won't touch exit_code again;
967 * other processors in this function are locked out.
969 p
->exit_code
= exit_code
;
972 if (unlikely(exit_code
== 0)) {
974 * Another thread in this function got to it first, or it
975 * resumed, or it resumed and then died.
977 write_unlock_irq(&tasklist_lock
);
979 read_lock(&tasklist_lock
);
983 /* move to end of parent's list to avoid starvation */
985 add_parent(p
, p
->parent
);
987 write_unlock_irq(&tasklist_lock
);
989 retval
= ru
? getrusage(p
, RUSAGE_BOTH
, ru
) : 0;
990 if (!retval
&& stat_addr
)
991 retval
= put_user((exit_code
<< 8) | 0x7f, stat_addr
);
1000 asmlinkage
long sys_wait4(pid_t pid
,unsigned int * stat_addr
, int options
, struct rusage
* ru
)
1002 DECLARE_WAITQUEUE(wait
, current
);
1003 struct task_struct
*tsk
;
1006 if (options
& ~(WNOHANG
|WUNTRACED
|__WNOTHREAD
|__WCLONE
|__WALL
))
1009 add_wait_queue(¤t
->wait_chldexit
,&wait
);
1012 current
->state
= TASK_INTERRUPTIBLE
;
1013 read_lock(&tasklist_lock
);
1016 struct task_struct
*p
;
1017 struct list_head
*_p
;
1020 list_for_each(_p
,&tsk
->children
) {
1021 p
= list_entry(_p
,struct task_struct
,sibling
);
1023 ret
= eligible_child(pid
, options
, p
);
1030 if (!(options
& WUNTRACED
) &&
1031 !(p
->ptrace
& PT_PTRACED
))
1033 retval
= wait_task_stopped(p
, ret
== 2,
1035 if (retval
!= 0) /* He released the lock. */
1040 * Eligible but we cannot release it yet:
1044 retval
= wait_task_zombie(p
, stat_addr
, ru
);
1045 if (retval
!= 0) /* He released the lock. */
1051 list_for_each (_p
,&tsk
->ptrace_children
) {
1052 p
= list_entry(_p
,struct task_struct
,ptrace_list
);
1053 if (!eligible_child(pid
, options
, p
))
1059 if (options
& __WNOTHREAD
)
1061 tsk
= next_thread(tsk
);
1062 if (tsk
->signal
!= current
->signal
)
1064 } while (tsk
!= current
);
1065 read_unlock(&tasklist_lock
);
1068 if (options
& WNOHANG
)
1070 retval
= -ERESTARTSYS
;
1071 if (signal_pending(current
))
1078 current
->state
= TASK_RUNNING
;
1079 remove_wait_queue(¤t
->wait_chldexit
,&wait
);
1083 #if !defined(__alpha__) && !defined(__ia64__) && !defined(__arm__)
1086 * sys_waitpid() remains for compatibility. waitpid() should be
1087 * implemented by calling sys_wait4() from libc.a.
1089 asmlinkage
long sys_waitpid(pid_t pid
,unsigned int * stat_addr
, int options
)
1091 return sys_wait4(pid
, stat_addr
, options
, NULL
);