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/iocontext.h>
16 #include <linux/key.h>
17 #include <linux/security.h>
18 #include <linux/cpu.h>
19 #include <linux/acct.h>
20 #include <linux/tsacct_kern.h>
21 #include <linux/file.h>
22 #include <linux/fdtable.h>
23 #include <linux/freezer.h>
24 #include <linux/binfmts.h>
25 #include <linux/nsproxy.h>
26 #include <linux/pid_namespace.h>
27 #include <linux/ptrace.h>
28 #include <linux/profile.h>
29 #include <linux/mount.h>
30 #include <linux/proc_fs.h>
31 #include <linux/kthread.h>
32 #include <linux/mempolicy.h>
33 #include <linux/taskstats_kern.h>
34 #include <linux/delayacct.h>
35 #include <linux/cgroup.h>
36 #include <linux/syscalls.h>
37 #include <linux/signal.h>
38 #include <linux/posix-timers.h>
39 #include <linux/cn_proc.h>
40 #include <linux/mutex.h>
41 #include <linux/futex.h>
42 #include <linux/pipe_fs_i.h>
43 #include <linux/audit.h> /* for audit_free() */
44 #include <linux/resource.h>
45 #include <linux/blkdev.h>
46 #include <linux/task_io_accounting_ops.h>
47 #include <linux/tracehook.h>
48 #include <linux/fs_struct.h>
49 #include <linux/init_task.h>
50 #include <linux/perf_event.h>
51 #include <trace/events/sched.h>
52 #include <linux/hw_breakpoint.h>
53 #include <linux/oom.h>
54 #include <linux/writeback.h>
55 #include <linux/shm.h>
57 #include <asm/uaccess.h>
58 #include <asm/unistd.h>
59 #include <asm/pgtable.h>
60 #include <asm/mmu_context.h>
62 #ifdef CONFIG_MT_PRIO_TRACER
63 # include <linux/prio_tracer.h>
66 static void exit_mm(struct task_struct
* tsk
);
68 static void __unhash_process(struct task_struct
*p
, bool group_dead
)
71 detach_pid(p
, PIDTYPE_PID
);
73 detach_pid(p
, PIDTYPE_PGID
);
74 detach_pid(p
, PIDTYPE_SID
);
76 list_del_rcu(&p
->tasks
);
77 list_del_init(&p
->sibling
);
78 __this_cpu_dec(process_counts
);
80 list_del_rcu(&p
->thread_group
);
81 list_del_rcu(&p
->thread_node
);
85 * This function expects the tasklist_lock write-locked.
87 static void __exit_signal(struct task_struct
*tsk
)
89 struct signal_struct
*sig
= tsk
->signal
;
90 bool group_dead
= thread_group_leader(tsk
);
91 struct sighand_struct
*sighand
;
92 struct tty_struct
*uninitialized_var(tty
);
93 cputime_t utime
, stime
;
95 sighand
= rcu_dereference_check(tsk
->sighand
,
96 lockdep_tasklist_lock_is_held());
97 spin_lock(&sighand
->siglock
);
99 posix_cpu_timers_exit(tsk
);
101 posix_cpu_timers_exit_group(tsk
);
106 * This can only happen if the caller is de_thread().
107 * FIXME: this is the temporary hack, we should teach
108 * posix-cpu-timers to handle this case correctly.
110 if (unlikely(has_group_leader_pid(tsk
)))
111 posix_cpu_timers_exit_group(tsk
);
114 * If there is any task waiting for the group exit
117 if (sig
->notify_count
> 0 && !--sig
->notify_count
)
118 wake_up_process(sig
->group_exit_task
);
120 if (tsk
== sig
->curr_target
)
121 sig
->curr_target
= next_thread(tsk
);
123 * Accumulate here the counters for all threads but the
124 * group leader as they die, so they can be added into
125 * the process-wide totals when those are taken.
126 * The group leader stays around as a zombie as long
127 * as there are other threads. When it gets reaped,
128 * the exit.c code will add its counts into these totals.
129 * We won't ever get here for the group leader, since it
130 * will have been the last reference on the signal_struct.
132 task_cputime(tsk
, &utime
, &stime
);
135 sig
->gtime
+= task_gtime(tsk
);
136 sig
->min_flt
+= tsk
->min_flt
;
137 sig
->maj_flt
+= tsk
->maj_flt
;
138 sig
->nvcsw
+= tsk
->nvcsw
;
139 sig
->nivcsw
+= tsk
->nivcsw
;
140 sig
->inblock
+= task_io_get_inblock(tsk
);
141 sig
->oublock
+= task_io_get_oublock(tsk
);
142 task_io_accounting_add(&sig
->ioac
, &tsk
->ioac
);
143 sig
->sum_sched_runtime
+= tsk
->se
.sum_exec_runtime
;
147 __unhash_process(tsk
, group_dead
);
150 * Do this under ->siglock, we can race with another thread
151 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
153 flush_sigqueue(&tsk
->pending
);
155 spin_unlock(&sighand
->siglock
);
157 __cleanup_sighand(sighand
);
158 clear_tsk_thread_flag(tsk
,TIF_SIGPENDING
);
160 flush_sigqueue(&sig
->shared_pending
);
165 static void delayed_put_task_struct(struct rcu_head
*rhp
)
167 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
169 perf_event_delayed_put(tsk
);
170 trace_sched_process_free(tsk
);
171 put_task_struct(tsk
);
175 void release_task(struct task_struct
* p
)
177 struct task_struct
*leader
;
180 /* don't need to get the RCU readlock here - the process is dead and
181 * can't be modifying its own credentials. But shut RCU-lockdep up */
183 atomic_dec(&__task_cred(p
)->user
->processes
);
188 write_lock_irq(&tasklist_lock
);
189 ptrace_release_task(p
);
193 * If we are the last non-leader member of the thread
194 * group, and the leader is zombie, then notify the
195 * group leader's parent process. (if it wants notification.)
198 leader
= p
->group_leader
;
199 if (leader
!= p
&& thread_group_empty(leader
) && leader
->exit_state
== EXIT_ZOMBIE
) {
201 * If we were the last child thread and the leader has
202 * exited already, and the leader's parent ignores SIGCHLD,
203 * then we are the one who should release the leader.
205 zap_leader
= do_notify_parent(leader
, leader
->exit_signal
);
207 leader
->exit_state
= EXIT_DEAD
;
210 write_unlock_irq(&tasklist_lock
);
212 call_rcu(&p
->rcu
, delayed_put_task_struct
);
215 if (unlikely(zap_leader
))
220 * This checks not only the pgrp, but falls back on the pid if no
221 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
224 * The caller must hold rcu lock or the tasklist lock.
226 struct pid
*session_of_pgrp(struct pid
*pgrp
)
228 struct task_struct
*p
;
229 struct pid
*sid
= NULL
;
231 p
= pid_task(pgrp
, PIDTYPE_PGID
);
233 p
= pid_task(pgrp
, PIDTYPE_PID
);
235 sid
= task_session(p
);
241 * Determine if a process group is "orphaned", according to the POSIX
242 * definition in 2.2.2.52. Orphaned process groups are not to be affected
243 * by terminal-generated stop signals. Newly orphaned process groups are
244 * to receive a SIGHUP and a SIGCONT.
246 * "I ask you, have you ever known what it is to be an orphan?"
248 static int will_become_orphaned_pgrp(struct pid
*pgrp
, struct task_struct
*ignored_task
)
250 struct task_struct
*p
;
252 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
253 if ((p
== ignored_task
) ||
254 (p
->exit_state
&& thread_group_empty(p
)) ||
255 is_global_init(p
->real_parent
))
258 if (task_pgrp(p
->real_parent
) != pgrp
&&
259 task_session(p
->real_parent
) == task_session(p
))
261 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
266 int is_current_pgrp_orphaned(void)
270 read_lock(&tasklist_lock
);
271 retval
= will_become_orphaned_pgrp(task_pgrp(current
), NULL
);
272 read_unlock(&tasklist_lock
);
277 static bool has_stopped_jobs(struct pid
*pgrp
)
279 struct task_struct
*p
;
281 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
282 if (p
->signal
->flags
& SIGNAL_STOP_STOPPED
)
284 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
290 * Check to see if any process groups have become orphaned as
291 * a result of our exiting, and if they have any stopped jobs,
292 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
295 kill_orphaned_pgrp(struct task_struct
*tsk
, struct task_struct
*parent
)
297 struct pid
*pgrp
= task_pgrp(tsk
);
298 struct task_struct
*ignored_task
= tsk
;
301 /* exit: our father is in a different pgrp than
302 * we are and we were the only connection outside.
304 parent
= tsk
->real_parent
;
306 /* reparent: our child is in a different pgrp than
307 * we are, and it was the only connection outside.
311 if (task_pgrp(parent
) != pgrp
&&
312 task_session(parent
) == task_session(tsk
) &&
313 will_become_orphaned_pgrp(pgrp
, ignored_task
) &&
314 has_stopped_jobs(pgrp
)) {
315 __kill_pgrp_info(SIGHUP
, SEND_SIG_PRIV
, pgrp
);
316 __kill_pgrp_info(SIGCONT
, SEND_SIG_PRIV
, pgrp
);
320 void __set_special_pids(struct pid
*pid
)
322 struct task_struct
*curr
= current
->group_leader
;
324 if (task_session(curr
) != pid
)
325 change_pid(curr
, PIDTYPE_SID
, pid
);
327 if (task_pgrp(curr
) != pid
)
328 change_pid(curr
, PIDTYPE_PGID
, pid
);
332 * Let kernel threads use this to say that they allow a certain signal.
333 * Must not be used if kthread was cloned with CLONE_SIGHAND.
335 int allow_signal(int sig
)
337 if (!valid_signal(sig
) || sig
< 1)
340 spin_lock_irq(¤t
->sighand
->siglock
);
341 /* This is only needed for daemonize()'ed kthreads */
342 sigdelset(¤t
->blocked
, sig
);
344 * Kernel threads handle their own signals. Let the signal code
345 * know it'll be handled, so that they don't get converted to
346 * SIGKILL or just silently dropped.
348 current
->sighand
->action
[(sig
)-1].sa
.sa_handler
= (void __user
*)2;
350 spin_unlock_irq(¤t
->sighand
->siglock
);
354 EXPORT_SYMBOL(allow_signal
);
356 int disallow_signal(int sig
)
358 if (!valid_signal(sig
) || sig
< 1)
361 spin_lock_irq(¤t
->sighand
->siglock
);
362 current
->sighand
->action
[(sig
)-1].sa
.sa_handler
= SIG_IGN
;
364 spin_unlock_irq(¤t
->sighand
->siglock
);
368 EXPORT_SYMBOL(disallow_signal
);
370 #ifdef CONFIG_MM_OWNER
372 * A task is exiting. If it owned this mm, find a new owner for the mm.
374 void mm_update_next_owner(struct mm_struct
*mm
)
376 struct task_struct
*c
, *g
, *p
= current
;
380 * If the exiting or execing task is not the owner, it's
381 * someone else's problem.
386 * The current owner is exiting/execing and there are no other
387 * candidates. Do not leave the mm pointing to a possibly
388 * freed task structure.
390 if (atomic_read(&mm
->mm_users
) <= 1) {
395 read_lock(&tasklist_lock
);
397 * Search in the children
399 list_for_each_entry(c
, &p
->children
, sibling
) {
401 goto assign_new_owner
;
405 * Search in the siblings
407 list_for_each_entry(c
, &p
->real_parent
->children
, sibling
) {
409 goto assign_new_owner
;
413 * Search through everything else. We should not get
416 do_each_thread(g
, c
) {
418 goto assign_new_owner
;
419 } while_each_thread(g
, c
);
421 read_unlock(&tasklist_lock
);
423 * We found no owner yet mm_users > 1: this implies that we are
424 * most likely racing with swapoff (try_to_unuse()) or /proc or
425 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
434 * The task_lock protects c->mm from changing.
435 * We always want mm->owner->mm == mm
439 * Delay read_unlock() till we have the task_lock()
440 * to ensure that c does not slip away underneath us
442 read_unlock(&tasklist_lock
);
452 #endif /* CONFIG_MM_OWNER */
455 * Turn us into a lazy TLB process if we
458 static void exit_mm(struct task_struct
* tsk
)
460 struct mm_struct
*mm
= tsk
->mm
;
461 struct core_state
*core_state
;
468 * Serialize with any possible pending coredump.
469 * We must hold mmap_sem around checking core_state
470 * and clearing tsk->mm. The core-inducing thread
471 * will increment ->nr_threads for each thread in the
472 * group with ->mm != NULL.
474 down_read(&mm
->mmap_sem
);
475 core_state
= mm
->core_state
;
477 struct core_thread self
;
478 up_read(&mm
->mmap_sem
);
481 self
.next
= xchg(&core_state
->dumper
.next
, &self
);
483 * Implies mb(), the result of xchg() must be visible
484 * to core_state->dumper.
486 if (atomic_dec_and_test(&core_state
->nr_threads
))
487 complete(&core_state
->startup
);
490 set_task_state(tsk
, TASK_UNINTERRUPTIBLE
);
491 if (!self
.task
) /* see coredump_finish() */
493 freezable_schedule();
495 __set_task_state(tsk
, TASK_RUNNING
);
496 down_read(&mm
->mmap_sem
);
498 atomic_inc(&mm
->mm_count
);
499 BUG_ON(mm
!= tsk
->active_mm
);
500 /* more a memory barrier than a real lock */
503 up_read(&mm
->mmap_sem
);
504 enter_lazy_tlb(mm
, current
);
506 mm_update_next_owner(mm
);
511 * When we die, we re-parent all our children, and try to:
512 * 1. give them to another thread in our thread group, if such a member exists
513 * 2. give it to the first ancestor process which prctl'd itself as a
514 * child_subreaper for its children (like a service manager)
515 * 3. give it to the init process (PID 1) in our pid namespace
517 static struct task_struct
*find_new_reaper(struct task_struct
*father
)
518 __releases(&tasklist_lock
)
519 __acquires(&tasklist_lock
)
521 struct pid_namespace
*pid_ns
= task_active_pid_ns(father
);
522 struct task_struct
*thread
;
525 while_each_thread(father
, thread
) {
526 if (thread
->flags
& PF_EXITING
)
528 if (unlikely(pid_ns
->child_reaper
== father
))
529 pid_ns
->child_reaper
= thread
;
533 if (unlikely(pid_ns
->child_reaper
== father
)) {
534 write_unlock_irq(&tasklist_lock
);
535 if (unlikely(pid_ns
== &init_pid_ns
)) {
536 panic("Attempted to kill init! exitcode=0x%08x\n",
537 father
->signal
->group_exit_code
?:
541 zap_pid_ns_processes(pid_ns
);
542 write_lock_irq(&tasklist_lock
);
543 } else if (father
->signal
->has_child_subreaper
) {
544 struct task_struct
*reaper
;
547 * Find the first ancestor marked as child_subreaper.
548 * Note that the code below checks same_thread_group(reaper,
549 * pid_ns->child_reaper). This is what we need to DTRT in a
550 * PID namespace. However we still need the check above, see
551 * http://marc.info/?l=linux-kernel&m=131385460420380
553 for (reaper
= father
->real_parent
;
554 reaper
!= &init_task
;
555 reaper
= reaper
->real_parent
) {
556 if (same_thread_group(reaper
, pid_ns
->child_reaper
))
558 if (!reaper
->signal
->is_child_subreaper
)
562 if (!(thread
->flags
& PF_EXITING
))
564 } while_each_thread(reaper
, thread
);
568 return pid_ns
->child_reaper
;
572 * Any that need to be release_task'd are put on the @dead list.
574 static void reparent_leader(struct task_struct
*father
, struct task_struct
*p
,
575 struct list_head
*dead
)
577 list_move_tail(&p
->sibling
, &p
->real_parent
->children
);
579 * If this is a threaded reparent there is no need to
580 * notify anyone anything has happened.
582 if (same_thread_group(p
->real_parent
, father
))
586 * We don't want people slaying init.
588 * Note: we do this even if it is EXIT_DEAD, wait_task_zombie()
589 * can change ->exit_state to EXIT_ZOMBIE. If this is the final
590 * state, do_notify_parent() was already called and ->exit_signal
593 p
->exit_signal
= SIGCHLD
;
595 if (p
->exit_state
== EXIT_DEAD
)
598 /* If it has exited notify the new parent about this child's death. */
600 p
->exit_state
== EXIT_ZOMBIE
&& thread_group_empty(p
)) {
601 if (do_notify_parent(p
, p
->exit_signal
)) {
602 p
->exit_state
= EXIT_DEAD
;
603 list_move_tail(&p
->sibling
, dead
);
607 kill_orphaned_pgrp(p
, father
);
610 static void forget_original_parent(struct task_struct
*father
)
612 struct task_struct
*p
, *n
, *reaper
;
613 LIST_HEAD(dead_children
);
615 write_lock_irq(&tasklist_lock
);
617 * Note that exit_ptrace() and find_new_reaper() might
618 * drop tasklist_lock and reacquire it.
621 reaper
= find_new_reaper(father
);
623 list_for_each_entry_safe(p
, n
, &father
->children
, sibling
) {
624 struct task_struct
*t
= p
;
626 t
->real_parent
= reaper
;
627 if (t
->parent
== father
) {
629 t
->parent
= t
->real_parent
;
631 if (t
->pdeath_signal
)
632 group_send_sig_info(t
->pdeath_signal
,
634 } while_each_thread(p
, t
);
635 reparent_leader(father
, p
, &dead_children
);
637 write_unlock_irq(&tasklist_lock
);
639 BUG_ON(!list_empty(&father
->children
));
641 list_for_each_entry_safe(p
, n
, &dead_children
, sibling
) {
642 list_del_init(&p
->sibling
);
648 * Send signals to all our closest relatives so that they know
649 * to properly mourn us..
651 static void exit_notify(struct task_struct
*tsk
, int group_dead
)
656 * This does two things:
658 * A. Make init inherit all the child processes
659 * B. Check to see if any process groups have become orphaned
660 * as a result of our exiting, and if they have any stopped
661 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
663 forget_original_parent(tsk
);
665 write_lock_irq(&tasklist_lock
);
667 kill_orphaned_pgrp(tsk
->group_leader
, NULL
);
669 if (unlikely(tsk
->ptrace
)) {
670 int sig
= thread_group_leader(tsk
) &&
671 thread_group_empty(tsk
) &&
672 !ptrace_reparented(tsk
) ?
673 tsk
->exit_signal
: SIGCHLD
;
674 autoreap
= do_notify_parent(tsk
, sig
);
675 } else if (thread_group_leader(tsk
)) {
676 autoreap
= thread_group_empty(tsk
) &&
677 do_notify_parent(tsk
, tsk
->exit_signal
);
682 tsk
->exit_state
= autoreap
? EXIT_DEAD
: EXIT_ZOMBIE
;
684 /* mt-exec, de_thread() is waiting for group leader */
685 if (unlikely(tsk
->signal
->notify_count
< 0))
686 wake_up_process(tsk
->signal
->group_exit_task
);
687 write_unlock_irq(&tasklist_lock
);
689 /* If the process is dead, release it - nobody will wait for it */
694 #ifdef CONFIG_DEBUG_STACK_USAGE
695 static void check_stack_usage(void)
697 static DEFINE_SPINLOCK(low_water_lock
);
698 static int lowest_to_date
= THREAD_SIZE
;
701 free
= stack_not_used(current
);
703 if (free
>= lowest_to_date
)
706 spin_lock(&low_water_lock
);
707 if (free
< lowest_to_date
) {
708 printk(KERN_WARNING
"%s (%d) used greatest stack depth: "
710 current
->comm
, task_pid_nr(current
), free
);
711 lowest_to_date
= free
;
713 spin_unlock(&low_water_lock
);
716 static inline void check_stack_usage(void) {}
719 #ifdef CONFIG_SCHEDSTATS
720 /* mt shceduler profiling*/
721 extern void end_mtproc_info(struct task_struct
*p
);
723 void do_exit(long code
)
725 struct task_struct
*tsk
= current
;
728 profile_task_exit(tsk
);
729 #ifdef CONFIG_SCHEDSTATS
730 /* mt shceduler profiling*/
731 printk(KERN_DEBUG
"[%d:%s] exit\n", tsk
->pid
, tsk
->comm
);
732 end_mtproc_info(tsk
);
735 #ifdef CONFIG_MT_PRIO_TRACER
736 delete_prio_tracer(tsk
->pid
);
739 WARN_ON(blk_needs_flush_plug(tsk
));
741 if (unlikely(in_interrupt()))
742 panic("Aiee, killing interrupt handler!");
743 if (unlikely(!tsk
->pid
))
744 panic("Attempted to kill the idle task!");
747 * If do_exit is called because this processes oopsed, it's possible
748 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
749 * continuing. Amongst other possible reasons, this is to prevent
750 * mm_release()->clear_child_tid() from writing to a user-controlled
755 ptrace_event(PTRACE_EVENT_EXIT
, code
);
757 validate_creds_for_do_exit(tsk
);
760 * We're taking recursive faults here in do_exit. Safest is to just
761 * leave this task alone and wait for reboot.
763 if (unlikely(tsk
->flags
& PF_EXITING
)) {
765 "Fixing recursive fault but reboot is needed!\n");
767 * We can do this unlocked here. The futex code uses
768 * this flag just to verify whether the pi state
769 * cleanup has been done or not. In the worst case it
770 * loops once more. We pretend that the cleanup was
771 * done as there is no way to return. Either the
772 * OWNER_DIED bit is set by now or we push the blocked
773 * task into the wait for ever nirwana as well.
775 tsk
->flags
|= PF_EXITPIDONE
;
776 set_current_state(TASK_UNINTERRUPTIBLE
);
780 exit_signals(tsk
); /* sets PF_EXITING */
782 * tsk->flags are checked in the futex code to protect against
783 * an exiting task cleaning up the robust pi futexes.
786 raw_spin_unlock_wait(&tsk
->pi_lock
);
788 if (unlikely(in_atomic()))
789 printk(KERN_INFO
"note: %s[%d] exited with preempt_count %d\n",
790 current
->comm
, task_pid_nr(current
),
793 acct_update_integrals(tsk
);
794 /* sync mm's RSS info before statistics gathering */
796 sync_mm_rss(tsk
->mm
);
797 group_dead
= atomic_dec_and_test(&tsk
->signal
->live
);
799 hrtimer_cancel(&tsk
->signal
->real_timer
);
800 exit_itimers(tsk
->signal
);
802 setmax_mm_hiwater_rss(&tsk
->signal
->maxrss
, tsk
->mm
);
804 acct_collect(code
, group_dead
);
809 tsk
->exit_code
= code
;
810 taskstats_exit(tsk
, group_dead
);
816 trace_sched_process_exit(tsk
);
823 disassociate_ctty(1);
824 exit_task_namespaces(tsk
);
830 * Flush inherited counters to the parent - before the parent
831 * gets woken up by child-exit notifications.
833 * because of cgroup mode, must be called before cgroup_exit()
835 perf_event_exit_task(tsk
);
839 module_put(task_thread_info(tsk
)->exec_domain
->module
);
841 proc_exit_connector(tsk
);
843 * FIXME: do that only when needed, using sched_exit tracepoint
845 ptrace_put_breakpoints(tsk
);
847 exit_notify(tsk
, group_dead
);
850 mpol_put(tsk
->mempolicy
);
851 tsk
->mempolicy
= NULL
;
855 if (unlikely(current
->pi_state_cache
))
856 kfree(current
->pi_state_cache
);
859 * Make sure we are holding no locks:
861 debug_check_no_locks_held();
863 * We can do this unlocked here. The futex code uses this flag
864 * just to verify whether the pi state cleanup has been done
865 * or not. In the worst case it loops once more.
867 tsk
->flags
|= PF_EXITPIDONE
;
870 exit_io_context(tsk
);
872 if (tsk
->splice_pipe
)
873 free_pipe_info(tsk
->splice_pipe
);
875 if (tsk
->task_frag
.page
)
876 put_page(tsk
->task_frag
.page
);
878 validate_creds_for_do_exit(tsk
);
882 __this_cpu_add(dirty_throttle_leaks
, tsk
->nr_dirtied
);
886 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
887 * when the following two conditions become true.
888 * - There is race condition of mmap_sem (It is acquired by
890 * - SMI occurs before setting TASK_RUNINNG.
891 * (or hypervisor of virtual machine switches to other guest)
892 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
894 * To avoid it, we have to wait for releasing tsk->pi_lock which
895 * is held by try_to_wake_up()
898 raw_spin_unlock_wait(&tsk
->pi_lock
);
900 /* causes final put_task_struct in finish_task_switch(). */
901 tsk
->state
= TASK_DEAD
;
902 tsk
->flags
|= PF_NOFREEZE
; /* tell freezer to ignore us */
905 /* Avoid "noreturn function does return". */
907 cpu_relax(); /* For when BUG is null */
910 EXPORT_SYMBOL_GPL(do_exit
);
912 void complete_and_exit(struct completion
*comp
, long code
)
920 EXPORT_SYMBOL(complete_and_exit
);
922 SYSCALL_DEFINE1(exit
, int, error_code
)
924 do_exit((error_code
&0xff)<<8);
928 * Take down every thread in the group. This is called by fatal signals
929 * as well as by sys_exit_group (below).
932 do_group_exit(int exit_code
)
934 struct signal_struct
*sig
= current
->signal
;
936 BUG_ON(exit_code
& 0x80); /* core dumps don't get here */
938 if (signal_group_exit(sig
))
939 exit_code
= sig
->group_exit_code
;
940 else if (!thread_group_empty(current
)) {
941 struct sighand_struct
*const sighand
= current
->sighand
;
942 spin_lock_irq(&sighand
->siglock
);
943 if (signal_group_exit(sig
))
944 /* Another thread got here before we took the lock. */
945 exit_code
= sig
->group_exit_code
;
947 sig
->group_exit_code
= exit_code
;
948 sig
->flags
= SIGNAL_GROUP_EXIT
;
949 zap_other_threads(current
);
951 spin_unlock_irq(&sighand
->siglock
);
959 * this kills every thread in the thread group. Note that any externally
960 * wait4()-ing process will get the correct exit code - even if this
961 * thread is not the thread group leader.
963 SYSCALL_DEFINE1(exit_group
, int, error_code
)
965 do_group_exit((error_code
& 0xff) << 8);
971 enum pid_type wo_type
;
975 struct siginfo __user
*wo_info
;
977 struct rusage __user
*wo_rusage
;
979 wait_queue_t child_wait
;
984 struct pid
*task_pid_type(struct task_struct
*task
, enum pid_type type
)
986 if (type
!= PIDTYPE_PID
)
987 task
= task
->group_leader
;
988 return task
->pids
[type
].pid
;
991 static int eligible_pid(struct wait_opts
*wo
, struct task_struct
*p
)
993 return wo
->wo_type
== PIDTYPE_MAX
||
994 task_pid_type(p
, wo
->wo_type
) == wo
->wo_pid
;
997 static int eligible_child(struct wait_opts
*wo
, struct task_struct
*p
)
999 if (!eligible_pid(wo
, p
))
1001 /* Wait for all children (clone and not) if __WALL is set;
1002 * otherwise, wait for clone children *only* if __WCLONE is
1003 * set; otherwise, wait for non-clone children *only*. (Note:
1004 * A "clone" child here is one that reports to its parent
1005 * using a signal other than SIGCHLD.) */
1006 if (((p
->exit_signal
!= SIGCHLD
) ^ !!(wo
->wo_flags
& __WCLONE
))
1007 && !(wo
->wo_flags
& __WALL
))
1013 static int wait_noreap_copyout(struct wait_opts
*wo
, struct task_struct
*p
,
1014 pid_t pid
, uid_t uid
, int why
, int status
)
1016 struct siginfo __user
*infop
;
1017 int retval
= wo
->wo_rusage
1018 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
1021 infop
= wo
->wo_info
;
1024 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1026 retval
= put_user(0, &infop
->si_errno
);
1028 retval
= put_user((short)why
, &infop
->si_code
);
1030 retval
= put_user(pid
, &infop
->si_pid
);
1032 retval
= put_user(uid
, &infop
->si_uid
);
1034 retval
= put_user(status
, &infop
->si_status
);
1042 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1043 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1044 * the lock and this task is uninteresting. If we return nonzero, we have
1045 * released the lock and the system call should return.
1047 static int wait_task_zombie(struct wait_opts
*wo
, struct task_struct
*p
)
1049 unsigned long state
;
1050 int retval
, status
, traced
;
1051 pid_t pid
= task_pid_vnr(p
);
1052 uid_t uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
1053 struct siginfo __user
*infop
;
1055 if (!likely(wo
->wo_flags
& WEXITED
))
1058 if (unlikely(wo
->wo_flags
& WNOWAIT
)) {
1059 int exit_code
= p
->exit_code
;
1063 read_unlock(&tasklist_lock
);
1064 if ((exit_code
& 0x7f) == 0) {
1066 status
= exit_code
>> 8;
1068 why
= (exit_code
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
1069 status
= exit_code
& 0x7f;
1071 return wait_noreap_copyout(wo
, p
, pid
, uid
, why
, status
);
1075 * Try to move the task's state to DEAD
1076 * only one thread is allowed to do this:
1078 state
= xchg(&p
->exit_state
, EXIT_DEAD
);
1079 if (state
!= EXIT_ZOMBIE
) {
1080 BUG_ON(state
!= EXIT_DEAD
);
1084 traced
= ptrace_reparented(p
);
1086 * It can be ptraced but not reparented, check
1087 * thread_group_leader() to filter out sub-threads.
1089 if (likely(!traced
) && thread_group_leader(p
)) {
1090 struct signal_struct
*psig
;
1091 struct signal_struct
*sig
;
1092 unsigned long maxrss
;
1093 cputime_t tgutime
, tgstime
;
1096 * The resource counters for the group leader are in its
1097 * own task_struct. Those for dead threads in the group
1098 * are in its signal_struct, as are those for the child
1099 * processes it has previously reaped. All these
1100 * accumulate in the parent's signal_struct c* fields.
1102 * We don't bother to take a lock here to protect these
1103 * p->signal fields, because they are only touched by
1104 * __exit_signal, which runs with tasklist_lock
1105 * write-locked anyway, and so is excluded here. We do
1106 * need to protect the access to parent->signal fields,
1107 * as other threads in the parent group can be right
1108 * here reaping other children at the same time.
1110 * We use thread_group_cputime_adjusted() to get times for the thread
1111 * group, which consolidates times for all threads in the
1112 * group including the group leader.
1114 thread_group_cputime_adjusted(p
, &tgutime
, &tgstime
);
1115 spin_lock_irq(&p
->real_parent
->sighand
->siglock
);
1116 psig
= p
->real_parent
->signal
;
1118 psig
->cutime
+= tgutime
+ sig
->cutime
;
1119 psig
->cstime
+= tgstime
+ sig
->cstime
;
1120 psig
->cgtime
+= task_gtime(p
) + sig
->gtime
+ sig
->cgtime
;
1122 p
->min_flt
+ sig
->min_flt
+ sig
->cmin_flt
;
1124 p
->maj_flt
+ sig
->maj_flt
+ sig
->cmaj_flt
;
1126 p
->nvcsw
+ sig
->nvcsw
+ sig
->cnvcsw
;
1128 p
->nivcsw
+ sig
->nivcsw
+ sig
->cnivcsw
;
1130 task_io_get_inblock(p
) +
1131 sig
->inblock
+ sig
->cinblock
;
1133 task_io_get_oublock(p
) +
1134 sig
->oublock
+ sig
->coublock
;
1135 maxrss
= max(sig
->maxrss
, sig
->cmaxrss
);
1136 if (psig
->cmaxrss
< maxrss
)
1137 psig
->cmaxrss
= maxrss
;
1138 task_io_accounting_add(&psig
->ioac
, &p
->ioac
);
1139 task_io_accounting_add(&psig
->ioac
, &sig
->ioac
);
1140 spin_unlock_irq(&p
->real_parent
->sighand
->siglock
);
1144 * Now we are sure this task is interesting, and no other
1145 * thread can reap it because we set its state to EXIT_DEAD.
1147 read_unlock(&tasklist_lock
);
1149 retval
= wo
->wo_rusage
1150 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
1151 status
= (p
->signal
->flags
& SIGNAL_GROUP_EXIT
)
1152 ? p
->signal
->group_exit_code
: p
->exit_code
;
1153 if (!retval
&& wo
->wo_stat
)
1154 retval
= put_user(status
, wo
->wo_stat
);
1156 infop
= wo
->wo_info
;
1157 if (!retval
&& infop
)
1158 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1159 if (!retval
&& infop
)
1160 retval
= put_user(0, &infop
->si_errno
);
1161 if (!retval
&& infop
) {
1164 if ((status
& 0x7f) == 0) {
1168 why
= (status
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
1171 retval
= put_user((short)why
, &infop
->si_code
);
1173 retval
= put_user(status
, &infop
->si_status
);
1175 if (!retval
&& infop
)
1176 retval
= put_user(pid
, &infop
->si_pid
);
1177 if (!retval
&& infop
)
1178 retval
= put_user(uid
, &infop
->si_uid
);
1183 write_lock_irq(&tasklist_lock
);
1184 /* We dropped tasklist, ptracer could die and untrace */
1187 * If this is not a sub-thread, notify the parent.
1188 * If parent wants a zombie, don't release it now.
1190 if (thread_group_leader(p
) &&
1191 !do_notify_parent(p
, p
->exit_signal
)) {
1192 p
->exit_state
= EXIT_ZOMBIE
;
1195 write_unlock_irq(&tasklist_lock
);
1203 static int *task_stopped_code(struct task_struct
*p
, bool ptrace
)
1206 if (task_is_stopped_or_traced(p
) &&
1207 !(p
->jobctl
& JOBCTL_LISTENING
))
1208 return &p
->exit_code
;
1210 if (p
->signal
->flags
& SIGNAL_STOP_STOPPED
)
1211 return &p
->signal
->group_exit_code
;
1217 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1219 * @ptrace: is the wait for ptrace
1220 * @p: task to wait for
1222 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1225 * read_lock(&tasklist_lock), which is released if return value is
1226 * non-zero. Also, grabs and releases @p->sighand->siglock.
1229 * 0 if wait condition didn't exist and search for other wait conditions
1230 * should continue. Non-zero return, -errno on failure and @p's pid on
1231 * success, implies that tasklist_lock is released and wait condition
1232 * search should terminate.
1234 static int wait_task_stopped(struct wait_opts
*wo
,
1235 int ptrace
, struct task_struct
*p
)
1237 struct siginfo __user
*infop
;
1238 int retval
, exit_code
, *p_code
, why
;
1239 uid_t uid
= 0; /* unneeded, required by compiler */
1243 * Traditionally we see ptrace'd stopped tasks regardless of options.
1245 if (!ptrace
&& !(wo
->wo_flags
& WUNTRACED
))
1248 if (!task_stopped_code(p
, ptrace
))
1252 spin_lock_irq(&p
->sighand
->siglock
);
1254 p_code
= task_stopped_code(p
, ptrace
);
1255 if (unlikely(!p_code
))
1258 exit_code
= *p_code
;
1262 if (!unlikely(wo
->wo_flags
& WNOWAIT
))
1265 uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
1267 spin_unlock_irq(&p
->sighand
->siglock
);
1272 * Now we are pretty sure this task is interesting.
1273 * Make sure it doesn't get reaped out from under us while we
1274 * give up the lock and then examine it below. We don't want to
1275 * keep holding onto the tasklist_lock while we call getrusage and
1276 * possibly take page faults for user memory.
1279 pid
= task_pid_vnr(p
);
1280 why
= ptrace
? CLD_TRAPPED
: CLD_STOPPED
;
1281 read_unlock(&tasklist_lock
);
1283 if (unlikely(wo
->wo_flags
& WNOWAIT
))
1284 return wait_noreap_copyout(wo
, p
, pid
, uid
, why
, exit_code
);
1286 retval
= wo
->wo_rusage
1287 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
1288 if (!retval
&& wo
->wo_stat
)
1289 retval
= put_user((exit_code
<< 8) | 0x7f, wo
->wo_stat
);
1291 infop
= wo
->wo_info
;
1292 if (!retval
&& infop
)
1293 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1294 if (!retval
&& infop
)
1295 retval
= put_user(0, &infop
->si_errno
);
1296 if (!retval
&& infop
)
1297 retval
= put_user((short)why
, &infop
->si_code
);
1298 if (!retval
&& infop
)
1299 retval
= put_user(exit_code
, &infop
->si_status
);
1300 if (!retval
&& infop
)
1301 retval
= put_user(pid
, &infop
->si_pid
);
1302 if (!retval
&& infop
)
1303 retval
= put_user(uid
, &infop
->si_uid
);
1313 * Handle do_wait work for one task in a live, non-stopped state.
1314 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1315 * the lock and this task is uninteresting. If we return nonzero, we have
1316 * released the lock and the system call should return.
1318 static int wait_task_continued(struct wait_opts
*wo
, struct task_struct
*p
)
1324 if (!unlikely(wo
->wo_flags
& WCONTINUED
))
1327 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
))
1330 spin_lock_irq(&p
->sighand
->siglock
);
1331 /* Re-check with the lock held. */
1332 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
)) {
1333 spin_unlock_irq(&p
->sighand
->siglock
);
1336 if (!unlikely(wo
->wo_flags
& WNOWAIT
))
1337 p
->signal
->flags
&= ~SIGNAL_STOP_CONTINUED
;
1338 uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
1339 spin_unlock_irq(&p
->sighand
->siglock
);
1341 pid
= task_pid_vnr(p
);
1343 read_unlock(&tasklist_lock
);
1346 retval
= wo
->wo_rusage
1347 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
1349 if (!retval
&& wo
->wo_stat
)
1350 retval
= put_user(0xffff, wo
->wo_stat
);
1354 retval
= wait_noreap_copyout(wo
, p
, pid
, uid
,
1355 CLD_CONTINUED
, SIGCONT
);
1356 BUG_ON(retval
== 0);
1363 * Consider @p for a wait by @parent.
1365 * -ECHILD should be in ->notask_error before the first call.
1366 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1367 * Returns zero if the search for a child should continue;
1368 * then ->notask_error is 0 if @p is an eligible child,
1369 * or another error from security_task_wait(), or still -ECHILD.
1371 static int wait_consider_task(struct wait_opts
*wo
, int ptrace
,
1372 struct task_struct
*p
)
1374 int ret
= eligible_child(wo
, p
);
1378 ret
= security_task_wait(p
);
1379 if (unlikely(ret
< 0)) {
1381 * If we have not yet seen any eligible child,
1382 * then let this error code replace -ECHILD.
1383 * A permission error will give the user a clue
1384 * to look for security policy problems, rather
1385 * than for mysterious wait bugs.
1387 if (wo
->notask_error
)
1388 wo
->notask_error
= ret
;
1392 /* dead body doesn't have much to contribute */
1393 if (unlikely(p
->exit_state
== EXIT_DEAD
)) {
1395 * But do not ignore this task until the tracer does
1396 * wait_task_zombie()->do_notify_parent().
1398 if (likely(!ptrace
) && unlikely(ptrace_reparented(p
)))
1399 wo
->notask_error
= 0;
1404 if (p
->exit_state
== EXIT_ZOMBIE
) {
1406 * A zombie ptracee is only visible to its ptracer.
1407 * Notification and reaping will be cascaded to the real
1408 * parent when the ptracer detaches.
1410 if (likely(!ptrace
) && unlikely(p
->ptrace
)) {
1411 /* it will become visible, clear notask_error */
1412 wo
->notask_error
= 0;
1416 /* we don't reap group leaders with subthreads */
1417 if (!delay_group_leader(p
))
1418 return wait_task_zombie(wo
, p
);
1421 * Allow access to stopped/continued state via zombie by
1422 * falling through. Clearing of notask_error is complex.
1426 * If WEXITED is set, notask_error should naturally be
1427 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1428 * so, if there are live subthreads, there are events to
1429 * wait for. If all subthreads are dead, it's still safe
1430 * to clear - this function will be called again in finite
1431 * amount time once all the subthreads are released and
1432 * will then return without clearing.
1436 * Stopped state is per-task and thus can't change once the
1437 * target task dies. Only continued and exited can happen.
1438 * Clear notask_error if WCONTINUED | WEXITED.
1440 if (likely(!ptrace
) || (wo
->wo_flags
& (WCONTINUED
| WEXITED
)))
1441 wo
->notask_error
= 0;
1444 * If @p is ptraced by a task in its real parent's group,
1445 * hide group stop/continued state when looking at @p as
1446 * the real parent; otherwise, a single stop can be
1447 * reported twice as group and ptrace stops.
1449 * If a ptracer wants to distinguish the two events for its
1450 * own children, it should create a separate process which
1451 * takes the role of real parent.
1453 if (likely(!ptrace
) && p
->ptrace
&& !ptrace_reparented(p
))
1457 * @p is alive and it's gonna stop, continue or exit, so
1458 * there always is something to wait for.
1460 wo
->notask_error
= 0;
1464 * Wait for stopped. Depending on @ptrace, different stopped state
1465 * is used and the two don't interact with each other.
1467 ret
= wait_task_stopped(wo
, ptrace
, p
);
1472 * Wait for continued. There's only one continued state and the
1473 * ptracer can consume it which can confuse the real parent. Don't
1474 * use WCONTINUED from ptracer. You don't need or want it.
1476 return wait_task_continued(wo
, p
);
1480 * Do the work of do_wait() for one thread in the group, @tsk.
1482 * -ECHILD should be in ->notask_error before the first call.
1483 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1484 * Returns zero if the search for a child should continue; then
1485 * ->notask_error is 0 if there were any eligible children,
1486 * or another error from security_task_wait(), or still -ECHILD.
1488 static int do_wait_thread(struct wait_opts
*wo
, struct task_struct
*tsk
)
1490 struct task_struct
*p
;
1492 list_for_each_entry(p
, &tsk
->children
, sibling
) {
1493 int ret
= wait_consider_task(wo
, 0, p
);
1501 static int ptrace_do_wait(struct wait_opts
*wo
, struct task_struct
*tsk
)
1503 struct task_struct
*p
;
1505 list_for_each_entry(p
, &tsk
->ptraced
, ptrace_entry
) {
1506 int ret
= wait_consider_task(wo
, 1, p
);
1514 static int child_wait_callback(wait_queue_t
*wait
, unsigned mode
,
1515 int sync
, void *key
)
1517 struct wait_opts
*wo
= container_of(wait
, struct wait_opts
,
1519 struct task_struct
*p
= key
;
1521 if (!eligible_pid(wo
, p
))
1524 if ((wo
->wo_flags
& __WNOTHREAD
) && wait
->private != p
->parent
)
1527 return default_wake_function(wait
, mode
, sync
, key
);
1530 void __wake_up_parent(struct task_struct
*p
, struct task_struct
*parent
)
1532 __wake_up_sync_key(&parent
->signal
->wait_chldexit
,
1533 TASK_INTERRUPTIBLE
, 1, p
);
1536 static long do_wait(struct wait_opts
*wo
)
1538 struct task_struct
*tsk
;
1541 trace_sched_process_wait(wo
->wo_pid
);
1543 init_waitqueue_func_entry(&wo
->child_wait
, child_wait_callback
);
1544 wo
->child_wait
.private = current
;
1545 add_wait_queue(¤t
->signal
->wait_chldexit
, &wo
->child_wait
);
1548 * If there is nothing that can match our critiera just get out.
1549 * We will clear ->notask_error to zero if we see any child that
1550 * might later match our criteria, even if we are not able to reap
1553 wo
->notask_error
= -ECHILD
;
1554 if ((wo
->wo_type
< PIDTYPE_MAX
) &&
1555 (!wo
->wo_pid
|| hlist_empty(&wo
->wo_pid
->tasks
[wo
->wo_type
])))
1558 set_current_state(TASK_INTERRUPTIBLE
);
1559 read_lock(&tasklist_lock
);
1562 retval
= do_wait_thread(wo
, tsk
);
1566 retval
= ptrace_do_wait(wo
, tsk
);
1570 if (wo
->wo_flags
& __WNOTHREAD
)
1572 } while_each_thread(current
, tsk
);
1573 read_unlock(&tasklist_lock
);
1576 retval
= wo
->notask_error
;
1577 if (!retval
&& !(wo
->wo_flags
& WNOHANG
)) {
1578 retval
= -ERESTARTSYS
;
1579 if (!signal_pending(current
)) {
1585 __set_current_state(TASK_RUNNING
);
1586 remove_wait_queue(¤t
->signal
->wait_chldexit
, &wo
->child_wait
);
1590 SYSCALL_DEFINE5(waitid
, int, which
, pid_t
, upid
, struct siginfo __user
*,
1591 infop
, int, options
, struct rusage __user
*, ru
)
1593 struct wait_opts wo
;
1594 struct pid
*pid
= NULL
;
1598 if (options
& ~(WNOHANG
|WNOWAIT
|WEXITED
|WSTOPPED
|WCONTINUED
))
1600 if (!(options
& (WEXITED
|WSTOPPED
|WCONTINUED
)))
1613 type
= PIDTYPE_PGID
;
1621 if (type
< PIDTYPE_MAX
)
1622 pid
= find_get_pid(upid
);
1626 wo
.wo_flags
= options
;
1636 * For a WNOHANG return, clear out all the fields
1637 * we would set so the user can easily tell the
1641 ret
= put_user(0, &infop
->si_signo
);
1643 ret
= put_user(0, &infop
->si_errno
);
1645 ret
= put_user(0, &infop
->si_code
);
1647 ret
= put_user(0, &infop
->si_pid
);
1649 ret
= put_user(0, &infop
->si_uid
);
1651 ret
= put_user(0, &infop
->si_status
);
1658 SYSCALL_DEFINE4(wait4
, pid_t
, upid
, int __user
*, stat_addr
,
1659 int, options
, struct rusage __user
*, ru
)
1661 struct wait_opts wo
;
1662 struct pid
*pid
= NULL
;
1666 if (options
& ~(WNOHANG
|WUNTRACED
|WCONTINUED
|
1667 __WNOTHREAD
|__WCLONE
|__WALL
))
1672 else if (upid
< 0) {
1673 type
= PIDTYPE_PGID
;
1674 pid
= find_get_pid(-upid
);
1675 } else if (upid
== 0) {
1676 type
= PIDTYPE_PGID
;
1677 pid
= get_task_pid(current
, PIDTYPE_PGID
);
1678 } else /* upid > 0 */ {
1680 pid
= find_get_pid(upid
);
1685 wo
.wo_flags
= options
| WEXITED
;
1687 wo
.wo_stat
= stat_addr
;
1695 #ifdef __ARCH_WANT_SYS_WAITPID
1698 * sys_waitpid() remains for compatibility. waitpid() should be
1699 * implemented by calling sys_wait4() from libc.a.
1701 SYSCALL_DEFINE3(waitpid
, pid_t
, pid
, int __user
*, stat_addr
, int, options
)
1703 return sys_wait4(pid
, stat_addr
, options
, NULL
);