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/binfmts.h>
24 #include <linux/nsproxy.h>
25 #include <linux/pid_namespace.h>
26 #include <linux/ptrace.h>
27 #include <linux/profile.h>
28 #include <linux/mount.h>
29 #include <linux/proc_fs.h>
30 #include <linux/kthread.h>
31 #include <linux/mempolicy.h>
32 #include <linux/taskstats_kern.h>
33 #include <linux/delayacct.h>
34 #include <linux/freezer.h>
35 #include <linux/cgroup.h>
36 #include <linux/syscalls.h>
37 #include <linux/signal.h>
38 #include <linux/posix-timers.h>
39 #include <linux/cn_proc.h>
40 #include <linux/mutex.h>
41 #include <linux/futex.h>
42 #include <linux/pipe_fs_i.h>
43 #include <linux/audit.h> /* for audit_free() */
44 #include <linux/resource.h>
45 #include <linux/blkdev.h>
46 #include <linux/task_io_accounting_ops.h>
47 #include <linux/tracehook.h>
48 #include <linux/fs_struct.h>
49 #include <linux/init_task.h>
50 #include <linux/perf_event.h>
51 #include <trace/events/sched.h>
52 #include <linux/hw_breakpoint.h>
53 #include <linux/oom.h>
54 #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 static void exit_mm(struct task_struct * tsk);
64 static void __unhash_process(struct task_struct *p, bool group_dead)
67 detach_pid(p, PIDTYPE_PID);
69 detach_pid(p, PIDTYPE_PGID);
70 detach_pid(p, PIDTYPE_SID);
72 list_del_rcu(&p->tasks);
73 list_del_init(&p->sibling);
74 __this_cpu_dec(process_counts);
76 list_del_rcu(&p->thread_group);
80 * This function expects the tasklist_lock write-locked.
82 static void __exit_signal(struct task_struct *tsk)
84 struct signal_struct *sig = tsk->signal;
85 bool group_dead = thread_group_leader(tsk);
86 struct sighand_struct *sighand;
87 struct tty_struct *uninitialized_var(tty);
89 sighand = rcu_dereference_check(tsk->sighand,
90 lockdep_tasklist_lock_is_held());
91 spin_lock(&sighand->siglock);
93 posix_cpu_timers_exit(tsk);
95 posix_cpu_timers_exit_group(tsk);
100 * This can only happen if the caller is de_thread().
101 * FIXME: this is the temporary hack, we should teach
102 * posix-cpu-timers to handle this case correctly.
104 if (unlikely(has_group_leader_pid(tsk)))
105 posix_cpu_timers_exit_group(tsk);
108 * If there is any task waiting for the group exit
111 if (sig->notify_count > 0 && !--sig->notify_count)
112 wake_up_process(sig->group_exit_task);
114 if (tsk == sig->curr_target)
115 sig->curr_target = next_thread(tsk);
117 * Accumulate here the counters for all threads but the
118 * group leader as they die, so they can be added into
119 * the process-wide totals when those are taken.
120 * The group leader stays around as a zombie as long
121 * as there are other threads. When it gets reaped,
122 * the exit.c code will add its counts into these totals.
123 * We won't ever get here for the group leader, since it
124 * will have been the last reference on the signal_struct.
126 sig->utime += tsk->utime;
127 sig->stime += tsk->stime;
128 sig->gtime += tsk->gtime;
129 sig->min_flt += tsk->min_flt;
130 sig->maj_flt += tsk->maj_flt;
131 sig->nvcsw += tsk->nvcsw;
132 sig->nivcsw += tsk->nivcsw;
133 sig->inblock += task_io_get_inblock(tsk);
134 sig->oublock += task_io_get_oublock(tsk);
135 task_io_accounting_add(&sig->ioac, &tsk->ioac);
136 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
140 __unhash_process(tsk, group_dead);
143 * Do this under ->siglock, we can race with another thread
144 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
146 flush_sigqueue(&tsk->pending);
148 spin_unlock(&sighand->siglock);
150 __cleanup_sighand(sighand);
151 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
153 flush_sigqueue(&sig->shared_pending);
158 static void delayed_put_task_struct(struct rcu_head *rhp)
160 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
162 perf_event_delayed_put(tsk);
163 trace_sched_process_free(tsk);
164 put_task_struct(tsk);
168 void release_task(struct task_struct * p)
170 struct task_struct *leader;
173 /* don't need to get the RCU readlock here - the process is dead and
174 * can't be modifying its own credentials. But shut RCU-lockdep up */
176 atomic_dec(&__task_cred(p)->user->processes);
181 write_lock_irq(&tasklist_lock);
182 ptrace_release_task(p);
186 * If we are the last non-leader member of the thread
187 * group, and the leader is zombie, then notify the
188 * group leader's parent process. (if it wants notification.)
191 leader = p->group_leader;
192 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
194 * If we were the last child thread and the leader has
195 * exited already, and the leader's parent ignores SIGCHLD,
196 * then we are the one who should release the leader.
198 zap_leader = do_notify_parent(leader, leader->exit_signal);
200 leader->exit_state = EXIT_DEAD;
203 write_unlock_irq(&tasklist_lock);
205 call_rcu(&p->rcu, delayed_put_task_struct);
208 if (unlikely(zap_leader))
213 * This checks not only the pgrp, but falls back on the pid if no
214 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
217 * The caller must hold rcu lock or the tasklist lock.
219 struct pid *session_of_pgrp(struct pid *pgrp)
221 struct task_struct *p;
222 struct pid *sid = NULL;
224 p = pid_task(pgrp, PIDTYPE_PGID);
226 p = pid_task(pgrp, PIDTYPE_PID);
228 sid = task_session(p);
234 * Determine if a process group is "orphaned", according to the POSIX
235 * definition in 2.2.2.52. Orphaned process groups are not to be affected
236 * by terminal-generated stop signals. Newly orphaned process groups are
237 * to receive a SIGHUP and a SIGCONT.
239 * "I ask you, have you ever known what it is to be an orphan?"
241 static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
243 struct task_struct *p;
245 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
246 if ((p == ignored_task) ||
247 (p->exit_state && thread_group_empty(p)) ||
248 is_global_init(p->real_parent))
251 if (task_pgrp(p->real_parent) != pgrp &&
252 task_session(p->real_parent) == task_session(p))
254 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
259 int is_current_pgrp_orphaned(void)
263 read_lock(&tasklist_lock);
264 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
265 read_unlock(&tasklist_lock);
270 static bool has_stopped_jobs(struct pid *pgrp)
272 struct task_struct *p;
274 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
275 if (p->signal->flags & SIGNAL_STOP_STOPPED)
277 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
283 * Check to see if any process groups have become orphaned as
284 * a result of our exiting, and if they have any stopped jobs,
285 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
288 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
290 struct pid *pgrp = task_pgrp(tsk);
291 struct task_struct *ignored_task = tsk;
294 /* exit: our father is in a different pgrp than
295 * we are and we were the only connection outside.
297 parent = tsk->real_parent;
299 /* reparent: our child is in a different pgrp than
300 * we are, and it was the only connection outside.
304 if (task_pgrp(parent) != pgrp &&
305 task_session(parent) == task_session(tsk) &&
306 will_become_orphaned_pgrp(pgrp, ignored_task) &&
307 has_stopped_jobs(pgrp)) {
308 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
309 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
314 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
316 * If a kernel thread is launched as a result of a system call, or if
317 * it ever exits, it should generally reparent itself to kthreadd so it
318 * isn't in the way of other processes and is correctly cleaned up on exit.
320 * The various task state such as scheduling policy and priority may have
321 * been inherited from a user process, so we reset them to sane values here.
323 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
325 static void reparent_to_kthreadd(void)
327 write_lock_irq(&tasklist_lock);
329 ptrace_unlink(current);
330 /* Reparent to init */
331 current->real_parent = current->parent = kthreadd_task;
332 list_move_tail(¤t->sibling, ¤t->real_parent->children);
334 /* Set the exit signal to SIGCHLD so we signal init on exit */
335 current->exit_signal = SIGCHLD;
337 if (task_nice(current) < 0)
338 set_user_nice(current, 0);
342 memcpy(current->signal->rlim, init_task.signal->rlim,
343 sizeof(current->signal->rlim));
345 atomic_inc(&init_cred.usage);
346 commit_creds(&init_cred);
347 write_unlock_irq(&tasklist_lock);
350 void __set_special_pids(struct pid *pid)
352 struct task_struct *curr = current->group_leader;
354 if (task_session(curr) != pid)
355 change_pid(curr, PIDTYPE_SID, pid);
357 if (task_pgrp(curr) != pid)
358 change_pid(curr, PIDTYPE_PGID, pid);
361 static void set_special_pids(struct pid *pid)
363 write_lock_irq(&tasklist_lock);
364 __set_special_pids(pid);
365 write_unlock_irq(&tasklist_lock);
369 * Let kernel threads use this to say that they allow a certain signal.
370 * Must not be used if kthread was cloned with CLONE_SIGHAND.
372 int allow_signal(int sig)
374 if (!valid_signal(sig) || sig < 1)
377 spin_lock_irq(¤t->sighand->siglock);
378 /* This is only needed for daemonize()'ed kthreads */
379 sigdelset(¤t->blocked, sig);
381 * Kernel threads handle their own signals. Let the signal code
382 * know it'll be handled, so that they don't get converted to
383 * SIGKILL or just silently dropped.
385 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
387 spin_unlock_irq(¤t->sighand->siglock);
391 EXPORT_SYMBOL(allow_signal);
393 int disallow_signal(int sig)
395 if (!valid_signal(sig) || sig < 1)
398 spin_lock_irq(¤t->sighand->siglock);
399 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
401 spin_unlock_irq(¤t->sighand->siglock);
405 EXPORT_SYMBOL(disallow_signal);
408 * Put all the gunge required to become a kernel thread without
409 * attached user resources in one place where it belongs.
412 void daemonize(const char *name, ...)
417 va_start(args, name);
418 vsnprintf(current->comm, sizeof(current->comm), name, args);
422 * If we were started as result of loading a module, close all of the
423 * user space pages. We don't need them, and if we didn't close them
424 * they would be locked into memory.
428 * We don't want to get frozen, in case system-wide hibernation
429 * or suspend transition begins right now.
431 current->flags |= (PF_NOFREEZE | PF_KTHREAD);
433 if (current->nsproxy != &init_nsproxy) {
434 get_nsproxy(&init_nsproxy);
435 switch_task_namespaces(current, &init_nsproxy);
437 set_special_pids(&init_struct_pid);
438 proc_clear_tty(current);
440 /* Block and flush all signals */
441 sigfillset(&blocked);
442 sigprocmask(SIG_BLOCK, &blocked, NULL);
443 flush_signals(current);
445 /* Become as one with the init task */
447 daemonize_fs_struct();
449 current->files = init_task.files;
450 atomic_inc(¤t->files->count);
452 reparent_to_kthreadd();
455 EXPORT_SYMBOL(daemonize);
457 static void close_files(struct files_struct * files)
465 * It is safe to dereference the fd table without RCU or
466 * ->file_lock because this is the last reference to the
467 * files structure. But use RCU to shut RCU-lockdep up.
470 fdt = files_fdtable(files);
475 if (i >= fdt->max_fds)
477 set = fdt->open_fds[j++];
480 struct file * file = xchg(&fdt->fd[i], NULL);
482 filp_close(file, files);
492 struct files_struct *get_files_struct(struct task_struct *task)
494 struct files_struct *files;
499 atomic_inc(&files->count);
505 void put_files_struct(struct files_struct *files)
509 if (atomic_dec_and_test(&files->count)) {
512 * Free the fd and fdset arrays if we expanded them.
513 * If the fdtable was embedded, pass files for freeing
514 * at the end of the RCU grace period. Otherwise,
515 * you can free files immediately.
518 fdt = files_fdtable(files);
519 if (fdt != &files->fdtab)
520 kmem_cache_free(files_cachep, files);
526 void reset_files_struct(struct files_struct *files)
528 struct task_struct *tsk = current;
529 struct files_struct *old;
535 put_files_struct(old);
538 void exit_files(struct task_struct *tsk)
540 struct files_struct * files = tsk->files;
546 put_files_struct(files);
550 #ifdef CONFIG_MM_OWNER
552 * A task is exiting. If it owned this mm, find a new owner for the mm.
554 void mm_update_next_owner(struct mm_struct *mm)
556 struct task_struct *c, *g, *p = current;
560 * If the exiting or execing task is not the owner, it's
561 * someone else's problem.
566 * The current owner is exiting/execing and there are no other
567 * candidates. Do not leave the mm pointing to a possibly
568 * freed task structure.
570 if (atomic_read(&mm->mm_users) <= 1) {
575 read_lock(&tasklist_lock);
577 * Search in the children
579 list_for_each_entry(c, &p->children, sibling) {
581 goto assign_new_owner;
585 * Search in the siblings
587 list_for_each_entry(c, &p->real_parent->children, sibling) {
589 goto assign_new_owner;
593 * Search through everything else. We should not get
596 do_each_thread(g, c) {
598 goto assign_new_owner;
599 } while_each_thread(g, c);
601 read_unlock(&tasklist_lock);
603 * We found no owner yet mm_users > 1: this implies that we are
604 * most likely racing with swapoff (try_to_unuse()) or /proc or
605 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
614 * The task_lock protects c->mm from changing.
615 * We always want mm->owner->mm == mm
619 * Delay read_unlock() till we have the task_lock()
620 * to ensure that c does not slip away underneath us
622 read_unlock(&tasklist_lock);
632 #endif /* CONFIG_MM_OWNER */
635 * Turn us into a lazy TLB process if we
638 static void exit_mm(struct task_struct * tsk)
640 struct mm_struct *mm = tsk->mm;
641 struct core_state *core_state;
647 * Serialize with any possible pending coredump.
648 * We must hold mmap_sem around checking core_state
649 * and clearing tsk->mm. The core-inducing thread
650 * will increment ->nr_threads for each thread in the
651 * group with ->mm != NULL.
653 down_read(&mm->mmap_sem);
654 core_state = mm->core_state;
656 struct core_thread self;
657 up_read(&mm->mmap_sem);
660 self.next = xchg(&core_state->dumper.next, &self);
662 * Implies mb(), the result of xchg() must be visible
663 * to core_state->dumper.
665 if (atomic_dec_and_test(&core_state->nr_threads))
666 complete(&core_state->startup);
669 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
670 if (!self.task) /* see coredump_finish() */
673 * If core_pattern is set to pipe, we could wait here
674 * for unbounded time. We don't want to prevent suspend.
675 * We also don't want to trigger the hung_task detector.
678 freezable_schedule();
680 __set_task_state(tsk, TASK_RUNNING);
681 down_read(&mm->mmap_sem);
683 atomic_inc(&mm->mm_count);
684 BUG_ON(mm != tsk->active_mm);
685 /* more a memory barrier than a real lock */
688 up_read(&mm->mmap_sem);
689 enter_lazy_tlb(mm, current);
691 mm_update_next_owner(mm);
696 * When we die, we re-parent all our children, and try to:
697 * 1. give them to another thread in our thread group, if such a member exists
698 * 2. give it to the first ancestor process which prctl'd itself as a
699 * child_subreaper for its children (like a service manager)
700 * 3. give it to the init process (PID 1) in our pid namespace
702 static struct task_struct *find_new_reaper(struct task_struct *father)
703 __releases(&tasklist_lock)
704 __acquires(&tasklist_lock)
706 struct pid_namespace *pid_ns = task_active_pid_ns(father);
707 struct task_struct *thread;
710 while_each_thread(father, thread) {
711 if (thread->flags & PF_EXITING)
713 if (unlikely(pid_ns->child_reaper == father))
714 pid_ns->child_reaper = thread;
718 if (unlikely(pid_ns->child_reaper == father)) {
719 write_unlock_irq(&tasklist_lock);
720 if (unlikely(pid_ns == &init_pid_ns)) {
721 panic("Attempted to kill init! exitcode=0x%08x\n",
722 father->signal->group_exit_code ?:
726 zap_pid_ns_processes(pid_ns);
727 write_lock_irq(&tasklist_lock);
729 * We can not clear ->child_reaper or leave it alone.
730 * There may by stealth EXIT_DEAD tasks on ->children,
731 * forget_original_parent() must move them somewhere.
733 pid_ns->child_reaper = init_pid_ns.child_reaper;
734 } else if (father->signal->has_child_subreaper) {
735 struct task_struct *reaper;
738 * Find the first ancestor marked as child_subreaper.
739 * Note that the code below checks same_thread_group(reaper,
740 * pid_ns->child_reaper). This is what we need to DTRT in a
741 * PID namespace. However we still need the check above, see
742 * http://marc.info/?l=linux-kernel&m=131385460420380
744 for (reaper = father->real_parent;
745 reaper != &init_task;
746 reaper = reaper->real_parent) {
747 if (same_thread_group(reaper, pid_ns->child_reaper))
749 if (!reaper->signal->is_child_subreaper)
753 if (!(thread->flags & PF_EXITING))
755 } while_each_thread(reaper, thread);
759 return pid_ns->child_reaper;
763 * Any that need to be release_task'd are put on the @dead list.
765 static void reparent_leader(struct task_struct *father, struct task_struct *p,
766 struct list_head *dead)
768 list_move_tail(&p->sibling, &p->real_parent->children);
770 if (p->exit_state == EXIT_DEAD)
773 * If this is a threaded reparent there is no need to
774 * notify anyone anything has happened.
776 if (same_thread_group(p->real_parent, father))
779 /* We don't want people slaying init. */
780 p->exit_signal = SIGCHLD;
782 /* If it has exited notify the new parent about this child's death. */
784 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
785 if (do_notify_parent(p, p->exit_signal)) {
786 p->exit_state = EXIT_DEAD;
787 list_move_tail(&p->sibling, dead);
791 kill_orphaned_pgrp(p, father);
794 static void forget_original_parent(struct task_struct *father)
796 struct task_struct *p, *n, *reaper;
797 LIST_HEAD(dead_children);
799 write_lock_irq(&tasklist_lock);
801 * Note that exit_ptrace() and find_new_reaper() might
802 * drop tasklist_lock and reacquire it.
805 reaper = find_new_reaper(father);
807 list_for_each_entry_safe(p, n, &father->children, sibling) {
808 struct task_struct *t = p;
810 t->real_parent = reaper;
811 if (t->parent == father) {
813 t->parent = t->real_parent;
815 if (t->pdeath_signal)
816 group_send_sig_info(t->pdeath_signal,
818 } while_each_thread(p, t);
819 reparent_leader(father, p, &dead_children);
821 write_unlock_irq(&tasklist_lock);
823 BUG_ON(!list_empty(&father->children));
825 list_for_each_entry_safe(p, n, &dead_children, sibling) {
826 list_del_init(&p->sibling);
832 * Send signals to all our closest relatives so that they know
833 * to properly mourn us..
835 static void exit_notify(struct task_struct *tsk, int group_dead)
840 * This does two things:
842 * A. Make init inherit all the child processes
843 * B. Check to see if any process groups have become orphaned
844 * as a result of our exiting, and if they have any stopped
845 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
847 forget_original_parent(tsk);
848 exit_task_namespaces(tsk);
850 write_lock_irq(&tasklist_lock);
852 kill_orphaned_pgrp(tsk->group_leader, NULL);
854 if (unlikely(tsk->ptrace)) {
855 int sig = thread_group_leader(tsk) &&
856 thread_group_empty(tsk) &&
857 !ptrace_reparented(tsk) ?
858 tsk->exit_signal : SIGCHLD;
859 autoreap = do_notify_parent(tsk, sig);
860 } else if (thread_group_leader(tsk)) {
861 autoreap = thread_group_empty(tsk) &&
862 do_notify_parent(tsk, tsk->exit_signal);
867 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
869 /* mt-exec, de_thread() is waiting for group leader */
870 if (unlikely(tsk->signal->notify_count < 0))
871 wake_up_process(tsk->signal->group_exit_task);
872 write_unlock_irq(&tasklist_lock);
874 /* If the process is dead, release it - nobody will wait for it */
879 #ifdef CONFIG_DEBUG_STACK_USAGE
880 static void check_stack_usage(void)
882 static DEFINE_SPINLOCK(low_water_lock);
883 static int lowest_to_date = THREAD_SIZE;
886 free = stack_not_used(current);
888 if (free >= lowest_to_date)
891 spin_lock(&low_water_lock);
892 if (free < lowest_to_date) {
893 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
895 current->comm, free);
896 lowest_to_date = free;
898 spin_unlock(&low_water_lock);
901 static inline void check_stack_usage(void) {}
904 void do_exit(long code)
906 struct task_struct *tsk = current;
909 profile_task_exit(tsk);
911 WARN_ON(blk_needs_flush_plug(tsk));
913 if (unlikely(in_interrupt()))
914 panic("Aiee, killing interrupt handler!");
915 if (unlikely(!tsk->pid))
916 panic("Attempted to kill the idle task!");
919 * If do_exit is called because this processes oopsed, it's possible
920 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
921 * continuing. Amongst other possible reasons, this is to prevent
922 * mm_release()->clear_child_tid() from writing to a user-controlled
927 ptrace_event(PTRACE_EVENT_EXIT, code);
929 validate_creds_for_do_exit(tsk);
932 * We're taking recursive faults here in do_exit. Safest is to just
933 * leave this task alone and wait for reboot.
935 if (unlikely(tsk->flags & PF_EXITING)) {
937 "Fixing recursive fault but reboot is needed!\n");
939 * We can do this unlocked here. The futex code uses
940 * this flag just to verify whether the pi state
941 * cleanup has been done or not. In the worst case it
942 * loops once more. We pretend that the cleanup was
943 * done as there is no way to return. Either the
944 * OWNER_DIED bit is set by now or we push the blocked
945 * task into the wait for ever nirwana as well.
947 tsk->flags |= PF_EXITPIDONE;
948 set_current_state(TASK_UNINTERRUPTIBLE);
952 exit_signals(tsk); /* sets PF_EXITING */
954 * tsk->flags are checked in the futex code to protect against
955 * an exiting task cleaning up the robust pi futexes.
958 raw_spin_unlock_wait(&tsk->pi_lock);
962 if (unlikely(in_atomic()))
963 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
964 current->comm, task_pid_nr(current),
967 acct_update_integrals(tsk);
968 /* sync mm's RSS info before statistics gathering */
970 sync_mm_rss(tsk->mm);
971 group_dead = atomic_dec_and_test(&tsk->signal->live);
973 hrtimer_cancel(&tsk->signal->real_timer);
974 exit_itimers(tsk->signal);
976 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
978 acct_collect(code, group_dead);
983 tsk->exit_code = code;
984 taskstats_exit(tsk, group_dead);
990 trace_sched_process_exit(tsk);
1000 * Flush inherited counters to the parent - before the parent
1001 * gets woken up by child-exit notifications.
1003 * because of cgroup mode, must be called before cgroup_exit()
1005 perf_event_exit_task(tsk);
1007 cgroup_exit(tsk, 1);
1010 disassociate_ctty(1);
1012 module_put(task_thread_info(tsk)->exec_domain->module);
1014 proc_exit_connector(tsk);
1017 * FIXME: do that only when needed, using sched_exit tracepoint
1019 ptrace_put_breakpoints(tsk);
1021 exit_notify(tsk, group_dead);
1024 mpol_put(tsk->mempolicy);
1025 tsk->mempolicy = NULL;
1029 if (unlikely(current->pi_state_cache))
1030 kfree(current->pi_state_cache);
1033 * Make sure we are holding no locks:
1035 debug_check_no_locks_held(tsk, "lock held at task exit time");
1037 * We can do this unlocked here. The futex code uses this flag
1038 * just to verify whether the pi state cleanup has been done
1039 * or not. In the worst case it loops once more.
1041 tsk->flags |= PF_EXITPIDONE;
1043 if (tsk->io_context)
1044 exit_io_context(tsk);
1046 if (tsk->splice_pipe)
1047 __free_pipe_info(tsk->splice_pipe);
1049 validate_creds_for_do_exit(tsk);
1052 if (tsk->nr_dirtied)
1053 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
1057 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
1058 * when the following two conditions become true.
1059 * - There is race condition of mmap_sem (It is acquired by
1061 * - SMI occurs before setting TASK_RUNINNG.
1062 * (or hypervisor of virtual machine switches to other guest)
1063 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
1065 * To avoid it, we have to wait for releasing tsk->pi_lock which
1066 * is held by try_to_wake_up()
1069 raw_spin_unlock_wait(&tsk->pi_lock);
1071 /* causes final put_task_struct in finish_task_switch(). */
1072 tsk->state = TASK_DEAD;
1073 tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */
1076 /* Avoid "noreturn function does return". */
1078 cpu_relax(); /* For when BUG is null */
1081 EXPORT_SYMBOL_GPL(do_exit);
1083 void complete_and_exit(struct completion *comp, long code)
1091 EXPORT_SYMBOL(complete_and_exit);
1093 SYSCALL_DEFINE1(exit, int, error_code)
1095 do_exit((error_code&0xff)<<8);
1099 * Take down every thread in the group. This is called by fatal signals
1100 * as well as by sys_exit_group (below).
1103 do_group_exit(int exit_code)
1105 struct signal_struct *sig = current->signal;
1107 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1109 if (signal_group_exit(sig))
1110 exit_code = sig->group_exit_code;
1111 else if (!thread_group_empty(current)) {
1112 struct sighand_struct *const sighand = current->sighand;
1113 spin_lock_irq(&sighand->siglock);
1114 if (signal_group_exit(sig))
1115 /* Another thread got here before we took the lock. */
1116 exit_code = sig->group_exit_code;
1118 sig->group_exit_code = exit_code;
1119 sig->flags = SIGNAL_GROUP_EXIT;
1120 zap_other_threads(current);
1122 spin_unlock_irq(&sighand->siglock);
1130 * this kills every thread in the thread group. Note that any externally
1131 * wait4()-ing process will get the correct exit code - even if this
1132 * thread is not the thread group leader.
1134 SYSCALL_DEFINE1(exit_group, int, error_code)
1136 do_group_exit((error_code & 0xff) << 8);
1142 enum pid_type wo_type;
1146 struct siginfo __user *wo_info;
1147 int __user *wo_stat;
1148 struct rusage __user *wo_rusage;
1150 wait_queue_t child_wait;
1155 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
1157 if (type != PIDTYPE_PID)
1158 task = task->group_leader;
1159 return task->pids[type].pid;
1162 static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
1164 return wo->wo_type == PIDTYPE_MAX ||
1165 task_pid_type(p, wo->wo_type) == wo->wo_pid;
1168 static int eligible_child(struct wait_opts *wo, struct task_struct *p)
1170 if (!eligible_pid(wo, p))
1172 /* Wait for all children (clone and not) if __WALL is set;
1173 * otherwise, wait for clone children *only* if __WCLONE is
1174 * set; otherwise, wait for non-clone children *only*. (Note:
1175 * A "clone" child here is one that reports to its parent
1176 * using a signal other than SIGCHLD.) */
1177 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
1178 && !(wo->wo_flags & __WALL))
1184 static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
1185 pid_t pid, uid_t uid, int why, int status)
1187 struct siginfo __user *infop;
1188 int retval = wo->wo_rusage
1189 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1192 infop = wo->wo_info;
1195 retval = put_user(SIGCHLD, &infop->si_signo);
1197 retval = put_user(0, &infop->si_errno);
1199 retval = put_user((short)why, &infop->si_code);
1201 retval = put_user(pid, &infop->si_pid);
1203 retval = put_user(uid, &infop->si_uid);
1205 retval = put_user(status, &infop->si_status);
1213 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1214 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1215 * the lock and this task is uninteresting. If we return nonzero, we have
1216 * released the lock and the system call should return.
1218 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
1220 unsigned long state;
1221 int retval, status, traced;
1222 pid_t pid = task_pid_vnr(p);
1223 uid_t uid = __task_cred(p)->uid;
1224 struct siginfo __user *infop;
1226 if (!likely(wo->wo_flags & WEXITED))
1229 if (unlikely(wo->wo_flags & WNOWAIT)) {
1230 int exit_code = p->exit_code;
1234 read_unlock(&tasklist_lock);
1235 if ((exit_code & 0x7f) == 0) {
1237 status = exit_code >> 8;
1239 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1240 status = exit_code & 0x7f;
1242 return wait_noreap_copyout(wo, p, pid, uid, why, status);
1246 * Try to move the task's state to DEAD
1247 * only one thread is allowed to do this:
1249 state = xchg(&p->exit_state, EXIT_DEAD);
1250 if (state != EXIT_ZOMBIE) {
1251 BUG_ON(state != EXIT_DEAD);
1255 traced = ptrace_reparented(p);
1257 * It can be ptraced but not reparented, check
1258 * thread_group_leader() to filter out sub-threads.
1260 if (likely(!traced) && thread_group_leader(p)) {
1261 struct signal_struct *psig;
1262 struct signal_struct *sig;
1263 unsigned long maxrss;
1264 cputime_t tgutime, tgstime;
1267 * The resource counters for the group leader are in its
1268 * own task_struct. Those for dead threads in the group
1269 * are in its signal_struct, as are those for the child
1270 * processes it has previously reaped. All these
1271 * accumulate in the parent's signal_struct c* fields.
1273 * We don't bother to take a lock here to protect these
1274 * p->signal fields, because they are only touched by
1275 * __exit_signal, which runs with tasklist_lock
1276 * write-locked anyway, and so is excluded here. We do
1277 * need to protect the access to parent->signal fields,
1278 * as other threads in the parent group can be right
1279 * here reaping other children at the same time.
1281 * We use thread_group_times() to get times for the thread
1282 * group, which consolidates times for all threads in the
1283 * group including the group leader.
1285 thread_group_times(p, &tgutime, &tgstime);
1286 spin_lock_irq(&p->real_parent->sighand->siglock);
1287 psig = p->real_parent->signal;
1289 psig->cutime += tgutime + sig->cutime;
1290 psig->cstime += tgstime + sig->cstime;
1291 psig->cgtime += p->gtime + sig->gtime + sig->cgtime;
1293 p->min_flt + sig->min_flt + sig->cmin_flt;
1295 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1297 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1299 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1301 task_io_get_inblock(p) +
1302 sig->inblock + sig->cinblock;
1304 task_io_get_oublock(p) +
1305 sig->oublock + sig->coublock;
1306 maxrss = max(sig->maxrss, sig->cmaxrss);
1307 if (psig->cmaxrss < maxrss)
1308 psig->cmaxrss = maxrss;
1309 task_io_accounting_add(&psig->ioac, &p->ioac);
1310 task_io_accounting_add(&psig->ioac, &sig->ioac);
1311 spin_unlock_irq(&p->real_parent->sighand->siglock);
1315 * Now we are sure this task is interesting, and no other
1316 * thread can reap it because we set its state to EXIT_DEAD.
1318 read_unlock(&tasklist_lock);
1320 retval = wo->wo_rusage
1321 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1322 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1323 ? p->signal->group_exit_code : p->exit_code;
1324 if (!retval && wo->wo_stat)
1325 retval = put_user(status, wo->wo_stat);
1327 infop = wo->wo_info;
1328 if (!retval && infop)
1329 retval = put_user(SIGCHLD, &infop->si_signo);
1330 if (!retval && infop)
1331 retval = put_user(0, &infop->si_errno);
1332 if (!retval && infop) {
1335 if ((status & 0x7f) == 0) {
1339 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1342 retval = put_user((short)why, &infop->si_code);
1344 retval = put_user(status, &infop->si_status);
1346 if (!retval && infop)
1347 retval = put_user(pid, &infop->si_pid);
1348 if (!retval && infop)
1349 retval = put_user(uid, &infop->si_uid);
1354 write_lock_irq(&tasklist_lock);
1355 /* We dropped tasklist, ptracer could die and untrace */
1358 * If this is not a sub-thread, notify the parent.
1359 * If parent wants a zombie, don't release it now.
1361 if (thread_group_leader(p) &&
1362 !do_notify_parent(p, p->exit_signal)) {
1363 p->exit_state = EXIT_ZOMBIE;
1366 write_unlock_irq(&tasklist_lock);
1374 static int *task_stopped_code(struct task_struct *p, bool ptrace)
1377 if (task_is_stopped_or_traced(p) &&
1378 !(p->jobctl & JOBCTL_LISTENING))
1379 return &p->exit_code;
1381 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1382 return &p->signal->group_exit_code;
1388 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1390 * @ptrace: is the wait for ptrace
1391 * @p: task to wait for
1393 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1396 * read_lock(&tasklist_lock), which is released if return value is
1397 * non-zero. Also, grabs and releases @p->sighand->siglock.
1400 * 0 if wait condition didn't exist and search for other wait conditions
1401 * should continue. Non-zero return, -errno on failure and @p's pid on
1402 * success, implies that tasklist_lock is released and wait condition
1403 * search should terminate.
1405 static int wait_task_stopped(struct wait_opts *wo,
1406 int ptrace, struct task_struct *p)
1408 struct siginfo __user *infop;
1409 int retval, exit_code, *p_code, why;
1410 uid_t uid = 0; /* unneeded, required by compiler */
1414 * Traditionally we see ptrace'd stopped tasks regardless of options.
1416 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1419 if (!task_stopped_code(p, ptrace))
1423 spin_lock_irq(&p->sighand->siglock);
1425 p_code = task_stopped_code(p, ptrace);
1426 if (unlikely(!p_code))
1429 exit_code = *p_code;
1433 if (!unlikely(wo->wo_flags & WNOWAIT))
1438 spin_unlock_irq(&p->sighand->siglock);
1443 * Now we are pretty sure this task is interesting.
1444 * Make sure it doesn't get reaped out from under us while we
1445 * give up the lock and then examine it below. We don't want to
1446 * keep holding onto the tasklist_lock while we call getrusage and
1447 * possibly take page faults for user memory.
1450 pid = task_pid_vnr(p);
1451 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1452 read_unlock(&tasklist_lock);
1454 if (unlikely(wo->wo_flags & WNOWAIT))
1455 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
1457 retval = wo->wo_rusage
1458 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1459 if (!retval && wo->wo_stat)
1460 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
1462 infop = wo->wo_info;
1463 if (!retval && infop)
1464 retval = put_user(SIGCHLD, &infop->si_signo);
1465 if (!retval && infop)
1466 retval = put_user(0, &infop->si_errno);
1467 if (!retval && infop)
1468 retval = put_user((short)why, &infop->si_code);
1469 if (!retval && infop)
1470 retval = put_user(exit_code, &infop->si_status);
1471 if (!retval && infop)
1472 retval = put_user(pid, &infop->si_pid);
1473 if (!retval && infop)
1474 retval = put_user(uid, &infop->si_uid);
1484 * Handle do_wait work for one task in a live, non-stopped state.
1485 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1486 * the lock and this task is uninteresting. If we return nonzero, we have
1487 * released the lock and the system call should return.
1489 static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1495 if (!unlikely(wo->wo_flags & WCONTINUED))
1498 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1501 spin_lock_irq(&p->sighand->siglock);
1502 /* Re-check with the lock held. */
1503 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1504 spin_unlock_irq(&p->sighand->siglock);
1507 if (!unlikely(wo->wo_flags & WNOWAIT))
1508 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1510 spin_unlock_irq(&p->sighand->siglock);
1512 pid = task_pid_vnr(p);
1514 read_unlock(&tasklist_lock);
1517 retval = wo->wo_rusage
1518 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1520 if (!retval && wo->wo_stat)
1521 retval = put_user(0xffff, wo->wo_stat);
1525 retval = wait_noreap_copyout(wo, p, pid, uid,
1526 CLD_CONTINUED, SIGCONT);
1527 BUG_ON(retval == 0);
1534 * Consider @p for a wait by @parent.
1536 * -ECHILD should be in ->notask_error before the first call.
1537 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1538 * Returns zero if the search for a child should continue;
1539 * then ->notask_error is 0 if @p is an eligible child,
1540 * or another error from security_task_wait(), or still -ECHILD.
1542 static int wait_consider_task(struct wait_opts *wo, int ptrace,
1543 struct task_struct *p)
1545 int ret = eligible_child(wo, p);
1549 ret = security_task_wait(p);
1550 if (unlikely(ret < 0)) {
1552 * If we have not yet seen any eligible child,
1553 * then let this error code replace -ECHILD.
1554 * A permission error will give the user a clue
1555 * to look for security policy problems, rather
1556 * than for mysterious wait bugs.
1558 if (wo->notask_error)
1559 wo->notask_error = ret;
1563 /* dead body doesn't have much to contribute */
1564 if (unlikely(p->exit_state == EXIT_DEAD)) {
1566 * But do not ignore this task until the tracer does
1567 * wait_task_zombie()->do_notify_parent().
1569 if (likely(!ptrace) && unlikely(ptrace_reparented(p)))
1570 wo->notask_error = 0;
1575 if (p->exit_state == EXIT_ZOMBIE) {
1577 * A zombie ptracee is only visible to its ptracer.
1578 * Notification and reaping will be cascaded to the real
1579 * parent when the ptracer detaches.
1581 if (likely(!ptrace) && unlikely(p->ptrace)) {
1582 /* it will become visible, clear notask_error */
1583 wo->notask_error = 0;
1587 /* we don't reap group leaders with subthreads */
1588 if (!delay_group_leader(p))
1589 return wait_task_zombie(wo, p);
1592 * Allow access to stopped/continued state via zombie by
1593 * falling through. Clearing of notask_error is complex.
1597 * If WEXITED is set, notask_error should naturally be
1598 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1599 * so, if there are live subthreads, there are events to
1600 * wait for. If all subthreads are dead, it's still safe
1601 * to clear - this function will be called again in finite
1602 * amount time once all the subthreads are released and
1603 * will then return without clearing.
1607 * Stopped state is per-task and thus can't change once the
1608 * target task dies. Only continued and exited can happen.
1609 * Clear notask_error if WCONTINUED | WEXITED.
1611 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1612 wo->notask_error = 0;
1615 * If @p is ptraced by a task in its real parent's group,
1616 * hide group stop/continued state when looking at @p as
1617 * the real parent; otherwise, a single stop can be
1618 * reported twice as group and ptrace stops.
1620 * If a ptracer wants to distinguish the two events for its
1621 * own children, it should create a separate process which
1622 * takes the role of real parent.
1624 if (likely(!ptrace) && p->ptrace && !ptrace_reparented(p))
1628 * @p is alive and it's gonna stop, continue or exit, so
1629 * there always is something to wait for.
1631 wo->notask_error = 0;
1635 * Wait for stopped. Depending on @ptrace, different stopped state
1636 * is used and the two don't interact with each other.
1638 ret = wait_task_stopped(wo, ptrace, p);
1643 * Wait for continued. There's only one continued state and the
1644 * ptracer can consume it which can confuse the real parent. Don't
1645 * use WCONTINUED from ptracer. You don't need or want it.
1647 return wait_task_continued(wo, p);
1651 * Do the work of do_wait() for one thread in the group, @tsk.
1653 * -ECHILD should be in ->notask_error before the first call.
1654 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1655 * Returns zero if the search for a child should continue; then
1656 * ->notask_error is 0 if there were any eligible children,
1657 * or another error from security_task_wait(), or still -ECHILD.
1659 static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1661 struct task_struct *p;
1663 list_for_each_entry(p, &tsk->children, sibling) {
1664 int ret = wait_consider_task(wo, 0, p);
1672 static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1674 struct task_struct *p;
1676 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1677 int ret = wait_consider_task(wo, 1, p);
1685 static int child_wait_callback(wait_queue_t *wait, unsigned mode,
1686 int sync, void *key)
1688 struct wait_opts *wo = container_of(wait, struct wait_opts,
1690 struct task_struct *p = key;
1692 if (!eligible_pid(wo, p))
1695 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1698 return default_wake_function(wait, mode, sync, key);
1701 void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1703 __wake_up_sync_key(&parent->signal->wait_chldexit,
1704 TASK_INTERRUPTIBLE, 1, p);
1707 static long do_wait(struct wait_opts *wo)
1709 struct task_struct *tsk;
1712 trace_sched_process_wait(wo->wo_pid);
1714 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1715 wo->child_wait.private = current;
1716 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1719 * If there is nothing that can match our critiera just get out.
1720 * We will clear ->notask_error to zero if we see any child that
1721 * might later match our criteria, even if we are not able to reap
1724 wo->notask_error = -ECHILD;
1725 if ((wo->wo_type < PIDTYPE_MAX) &&
1726 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1729 set_current_state(TASK_INTERRUPTIBLE);
1730 read_lock(&tasklist_lock);
1733 retval = do_wait_thread(wo, tsk);
1737 retval = ptrace_do_wait(wo, tsk);
1741 if (wo->wo_flags & __WNOTHREAD)
1743 } while_each_thread(current, tsk);
1744 read_unlock(&tasklist_lock);
1747 retval = wo->notask_error;
1748 if (!retval && !(wo->wo_flags & WNOHANG)) {
1749 retval = -ERESTARTSYS;
1750 if (!signal_pending(current)) {
1756 __set_current_state(TASK_RUNNING);
1757 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1761 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1762 infop, int, options, struct rusage __user *, ru)
1764 struct wait_opts wo;
1765 struct pid *pid = NULL;
1769 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1771 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1784 type = PIDTYPE_PGID;
1792 if (type < PIDTYPE_MAX)
1793 pid = find_get_pid(upid);
1797 wo.wo_flags = options;
1807 * For a WNOHANG return, clear out all the fields
1808 * we would set so the user can easily tell the
1812 ret = put_user(0, &infop->si_signo);
1814 ret = put_user(0, &infop->si_errno);
1816 ret = put_user(0, &infop->si_code);
1818 ret = put_user(0, &infop->si_pid);
1820 ret = put_user(0, &infop->si_uid);
1822 ret = put_user(0, &infop->si_status);
1827 /* avoid REGPARM breakage on x86: */
1828 asmlinkage_protect(5, ret, which, upid, infop, options, ru);
1832 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1833 int, options, struct rusage __user *, ru)
1835 struct wait_opts wo;
1836 struct pid *pid = NULL;
1840 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1841 __WNOTHREAD|__WCLONE|__WALL))
1846 else if (upid < 0) {
1847 type = PIDTYPE_PGID;
1848 pid = find_get_pid(-upid);
1849 } else if (upid == 0) {
1850 type = PIDTYPE_PGID;
1851 pid = get_task_pid(current, PIDTYPE_PGID);
1852 } else /* upid > 0 */ {
1854 pid = find_get_pid(upid);
1859 wo.wo_flags = options | WEXITED;
1861 wo.wo_stat = stat_addr;
1866 /* avoid REGPARM breakage on x86: */
1867 asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
1871 #ifdef __ARCH_WANT_SYS_WAITPID
1874 * sys_waitpid() remains for compatibility. waitpid() should be
1875 * implemented by calling sys_wait4() from libc.a.
1877 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1879 return sys_wait4(pid, stat_addr, options, NULL);