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 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);
77 list_del_rcu(&p->thread_node);
81 * This function expects the tasklist_lock write-locked.
83 static void __exit_signal(struct task_struct *tsk)
85 struct signal_struct *sig = tsk->signal;
86 bool group_dead = thread_group_leader(tsk);
87 struct sighand_struct *sighand;
88 struct tty_struct *uninitialized_var(tty);
89 cputime_t utime, stime;
91 sighand = rcu_dereference_check(tsk->sighand,
92 lockdep_tasklist_lock_is_held());
93 spin_lock(&sighand->siglock);
95 posix_cpu_timers_exit(tsk);
97 posix_cpu_timers_exit_group(tsk);
102 * This can only happen if the caller is de_thread().
103 * FIXME: this is the temporary hack, we should teach
104 * posix-cpu-timers to handle this case correctly.
106 if (unlikely(has_group_leader_pid(tsk)))
107 posix_cpu_timers_exit_group(tsk);
110 * If there is any task waiting for the group exit
113 if (sig->notify_count > 0 && !--sig->notify_count)
114 wake_up_process(sig->group_exit_task);
116 if (tsk == sig->curr_target)
117 sig->curr_target = next_thread(tsk);
121 * Accumulate here the counters for all threads as they die. We could
122 * skip the group leader because it is the last user of signal_struct,
123 * but we want to avoid the race with thread_group_cputime() which can
124 * see the empty ->thread_head list.
126 task_cputime(tsk, &utime, &stime);
127 write_seqlock(&sig->stats_lock);
130 sig->gtime += task_gtime(tsk);
131 sig->min_flt += tsk->min_flt;
132 sig->maj_flt += tsk->maj_flt;
133 sig->nvcsw += tsk->nvcsw;
134 sig->nivcsw += tsk->nivcsw;
135 sig->inblock += task_io_get_inblock(tsk);
136 sig->oublock += task_io_get_oublock(tsk);
137 task_io_accounting_add(&sig->ioac, &tsk->ioac);
138 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
140 __unhash_process(tsk, group_dead);
141 write_sequnlock(&sig->stats_lock);
144 * Do this under ->siglock, we can race with another thread
145 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
147 flush_sigqueue(&tsk->pending);
149 spin_unlock(&sighand->siglock);
151 __cleanup_sighand(sighand);
152 clear_tsk_thread_flag(tsk, TIF_SIGPENDING);
154 flush_sigqueue(&sig->shared_pending);
159 static void delayed_put_task_struct(struct rcu_head *rhp)
161 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
163 perf_event_delayed_put(tsk);
164 trace_sched_process_free(tsk);
165 put_task_struct(tsk);
169 void release_task(struct task_struct *p)
171 struct task_struct *leader;
174 /* don't need to get the RCU readlock here - the process is dead and
175 * can't be modifying its own credentials. But shut RCU-lockdep up */
177 atomic_dec(&__task_cred(p)->user->processes);
182 write_lock_irq(&tasklist_lock);
183 ptrace_release_task(p);
187 * If we are the last non-leader member of the thread
188 * group, and the leader is zombie, then notify the
189 * group leader's parent process. (if it wants notification.)
192 leader = p->group_leader;
193 if (leader != p && thread_group_empty(leader)
194 && leader->exit_state == EXIT_ZOMBIE) {
196 * If we were the last child thread and the leader has
197 * exited already, and the leader's parent ignores SIGCHLD,
198 * then we are the one who should release the leader.
200 zap_leader = do_notify_parent(leader, leader->exit_signal);
202 leader->exit_state = EXIT_DEAD;
205 write_unlock_irq(&tasklist_lock);
207 call_rcu(&p->rcu, delayed_put_task_struct);
210 if (unlikely(zap_leader))
215 * This checks not only the pgrp, but falls back on the pid if no
216 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
219 * The caller must hold rcu lock or the tasklist lock.
221 struct pid *session_of_pgrp(struct pid *pgrp)
223 struct task_struct *p;
224 struct pid *sid = NULL;
226 p = pid_task(pgrp, PIDTYPE_PGID);
228 p = pid_task(pgrp, PIDTYPE_PID);
230 sid = task_session(p);
236 * Determine if a process group is "orphaned", according to the POSIX
237 * definition in 2.2.2.52. Orphaned process groups are not to be affected
238 * by terminal-generated stop signals. Newly orphaned process groups are
239 * to receive a SIGHUP and a SIGCONT.
241 * "I ask you, have you ever known what it is to be an orphan?"
243 static int will_become_orphaned_pgrp(struct pid *pgrp,
244 struct task_struct *ignored_task)
246 struct task_struct *p;
248 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
249 if ((p == ignored_task) ||
250 (p->exit_state && thread_group_empty(p)) ||
251 is_global_init(p->real_parent))
254 if (task_pgrp(p->real_parent) != pgrp &&
255 task_session(p->real_parent) == task_session(p))
257 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
262 int is_current_pgrp_orphaned(void)
266 read_lock(&tasklist_lock);
267 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
268 read_unlock(&tasklist_lock);
273 static bool has_stopped_jobs(struct pid *pgrp)
275 struct task_struct *p;
277 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
278 if (p->signal->flags & SIGNAL_STOP_STOPPED)
280 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
286 * Check to see if any process groups have become orphaned as
287 * a result of our exiting, and if they have any stopped jobs,
288 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
291 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
293 struct pid *pgrp = task_pgrp(tsk);
294 struct task_struct *ignored_task = tsk;
297 /* exit: our father is in a different pgrp than
298 * we are and we were the only connection outside.
300 parent = tsk->real_parent;
302 /* reparent: our child is in a different pgrp than
303 * we are, and it was the only connection outside.
307 if (task_pgrp(parent) != pgrp &&
308 task_session(parent) == task_session(tsk) &&
309 will_become_orphaned_pgrp(pgrp, ignored_task) &&
310 has_stopped_jobs(pgrp)) {
311 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
312 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
318 * A task is exiting. If it owned this mm, find a new owner for the mm.
320 void mm_update_next_owner(struct mm_struct *mm)
322 struct task_struct *c, *g, *p = current;
326 * If the exiting or execing task is not the owner, it's
327 * someone else's problem.
332 * The current owner is exiting/execing and there are no other
333 * candidates. Do not leave the mm pointing to a possibly
334 * freed task structure.
336 if (atomic_read(&mm->mm_users) <= 1) {
341 read_lock(&tasklist_lock);
343 * Search in the children
345 list_for_each_entry(c, &p->children, sibling) {
347 goto assign_new_owner;
351 * Search in the siblings
353 list_for_each_entry(c, &p->real_parent->children, sibling) {
355 goto assign_new_owner;
359 * Search through everything else, we should not get here often.
361 for_each_process(g) {
362 if (g->flags & PF_KTHREAD)
364 for_each_thread(g, c) {
366 goto assign_new_owner;
371 read_unlock(&tasklist_lock);
373 * We found no owner yet mm_users > 1: this implies that we are
374 * most likely racing with swapoff (try_to_unuse()) or /proc or
375 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
384 * The task_lock protects c->mm from changing.
385 * We always want mm->owner->mm == mm
389 * Delay read_unlock() till we have the task_lock()
390 * to ensure that c does not slip away underneath us
392 read_unlock(&tasklist_lock);
402 #endif /* CONFIG_MEMCG */
405 * Turn us into a lazy TLB process if we
408 static void exit_mm(struct task_struct *tsk)
410 struct mm_struct *mm = tsk->mm;
411 struct core_state *core_state;
418 * Serialize with any possible pending coredump.
419 * We must hold mmap_sem around checking core_state
420 * and clearing tsk->mm. The core-inducing thread
421 * will increment ->nr_threads for each thread in the
422 * group with ->mm != NULL.
424 down_read(&mm->mmap_sem);
425 core_state = mm->core_state;
427 struct core_thread self;
429 up_read(&mm->mmap_sem);
432 self.next = xchg(&core_state->dumper.next, &self);
434 * Implies mb(), the result of xchg() must be visible
435 * to core_state->dumper.
437 if (atomic_dec_and_test(&core_state->nr_threads))
438 complete(&core_state->startup);
441 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
442 if (!self.task) /* see coredump_finish() */
444 freezable_schedule();
446 __set_task_state(tsk, TASK_RUNNING);
447 down_read(&mm->mmap_sem);
449 atomic_inc(&mm->mm_count);
450 BUG_ON(mm != tsk->active_mm);
451 /* more a memory barrier than a real lock */
454 up_read(&mm->mmap_sem);
455 enter_lazy_tlb(mm, current);
457 mm_update_next_owner(mm);
459 clear_thread_flag(TIF_MEMDIE);
462 static struct task_struct *find_alive_thread(struct task_struct *p)
464 struct task_struct *t;
466 for_each_thread(p, t) {
467 if (!(t->flags & PF_EXITING))
473 static struct task_struct *find_child_reaper(struct task_struct *father)
474 __releases(&tasklist_lock)
475 __acquires(&tasklist_lock)
477 struct pid_namespace *pid_ns = task_active_pid_ns(father);
478 struct task_struct *reaper = pid_ns->child_reaper;
480 if (likely(reaper != father))
483 reaper = find_alive_thread(father);
485 pid_ns->child_reaper = reaper;
489 write_unlock_irq(&tasklist_lock);
490 if (unlikely(pid_ns == &init_pid_ns)) {
491 panic("Attempted to kill init! exitcode=0x%08x\n",
492 father->signal->group_exit_code ?: father->exit_code);
494 zap_pid_ns_processes(pid_ns);
495 write_lock_irq(&tasklist_lock);
501 * When we die, we re-parent all our children, and try to:
502 * 1. give them to another thread in our thread group, if such a member exists
503 * 2. give it to the first ancestor process which prctl'd itself as a
504 * child_subreaper for its children (like a service manager)
505 * 3. give it to the init process (PID 1) in our pid namespace
507 static struct task_struct *find_new_reaper(struct task_struct *father,
508 struct task_struct *child_reaper)
510 struct task_struct *thread, *reaper;
512 thread = find_alive_thread(father);
516 if (father->signal->has_child_subreaper) {
518 * Find the first ->is_child_subreaper ancestor in our pid_ns.
519 * We start from father to ensure we can not look into another
520 * namespace, this is safe because all its threads are dead.
522 for (reaper = father;
523 !same_thread_group(reaper, child_reaper);
524 reaper = reaper->real_parent) {
525 /* call_usermodehelper() descendants need this check */
526 if (reaper == &init_task)
528 if (!reaper->signal->is_child_subreaper)
530 thread = find_alive_thread(reaper);
540 * Any that need to be release_task'd are put on the @dead list.
542 static void reparent_leader(struct task_struct *father, struct task_struct *p,
543 struct list_head *dead)
545 if (unlikely(p->exit_state == EXIT_DEAD))
548 /* We don't want people slaying init. */
549 p->exit_signal = SIGCHLD;
551 /* If it has exited notify the new parent about this child's death. */
553 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
554 if (do_notify_parent(p, p->exit_signal)) {
555 p->exit_state = EXIT_DEAD;
556 list_add(&p->ptrace_entry, dead);
560 kill_orphaned_pgrp(p, father);
564 * This does two things:
566 * A. Make init inherit all the child processes
567 * B. Check to see if any process groups have become orphaned
568 * as a result of our exiting, and if they have any stopped
569 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
571 static void forget_original_parent(struct task_struct *father,
572 struct list_head *dead)
574 struct task_struct *p, *t, *reaper;
576 if (unlikely(!list_empty(&father->ptraced)))
577 exit_ptrace(father, dead);
579 /* Can drop and reacquire tasklist_lock */
580 reaper = find_child_reaper(father);
581 if (list_empty(&father->children))
584 reaper = find_new_reaper(father, reaper);
585 list_for_each_entry(p, &father->children, sibling) {
586 for_each_thread(p, t) {
587 t->real_parent = reaper;
588 BUG_ON((!t->ptrace) != (t->parent == father));
589 if (likely(!t->ptrace))
590 t->parent = t->real_parent;
591 if (t->pdeath_signal)
592 group_send_sig_info(t->pdeath_signal,
596 * If this is a threaded reparent there is no need to
597 * notify anyone anything has happened.
599 if (!same_thread_group(reaper, father))
600 reparent_leader(father, p, dead);
602 list_splice_tail_init(&father->children, &reaper->children);
606 * Send signals to all our closest relatives so that they know
607 * to properly mourn us..
609 static void exit_notify(struct task_struct *tsk, int group_dead)
612 struct task_struct *p, *n;
615 write_lock_irq(&tasklist_lock);
616 forget_original_parent(tsk, &dead);
619 kill_orphaned_pgrp(tsk->group_leader, NULL);
621 if (unlikely(tsk->ptrace)) {
622 int sig = thread_group_leader(tsk) &&
623 thread_group_empty(tsk) &&
624 !ptrace_reparented(tsk) ?
625 tsk->exit_signal : SIGCHLD;
626 autoreap = do_notify_parent(tsk, sig);
627 } else if (thread_group_leader(tsk)) {
628 autoreap = thread_group_empty(tsk) &&
629 do_notify_parent(tsk, tsk->exit_signal);
634 tsk->exit_state = autoreap ? EXIT_DEAD : EXIT_ZOMBIE;
635 if (tsk->exit_state == EXIT_DEAD)
636 list_add(&tsk->ptrace_entry, &dead);
638 /* mt-exec, de_thread() is waiting for group leader */
639 if (unlikely(tsk->signal->notify_count < 0))
640 wake_up_process(tsk->signal->group_exit_task);
641 write_unlock_irq(&tasklist_lock);
643 list_for_each_entry_safe(p, n, &dead, ptrace_entry) {
644 list_del_init(&p->ptrace_entry);
649 #ifdef CONFIG_DEBUG_STACK_USAGE
650 static void check_stack_usage(void)
652 static DEFINE_SPINLOCK(low_water_lock);
653 static int lowest_to_date = THREAD_SIZE;
656 free = stack_not_used(current);
658 if (free >= lowest_to_date)
661 spin_lock(&low_water_lock);
662 if (free < lowest_to_date) {
663 pr_warn("%s (%d) used greatest stack depth: %lu bytes left\n",
664 current->comm, task_pid_nr(current), free);
665 lowest_to_date = free;
667 spin_unlock(&low_water_lock);
670 static inline void check_stack_usage(void) {}
673 void do_exit(long code)
675 struct task_struct *tsk = current;
677 TASKS_RCU(int tasks_rcu_i);
679 profile_task_exit(tsk);
681 WARN_ON(blk_needs_flush_plug(tsk));
683 if (unlikely(in_interrupt()))
684 panic("Aiee, killing interrupt handler!");
685 if (unlikely(!tsk->pid))
686 panic("Attempted to kill the idle task!");
689 * If do_exit is called because this processes oopsed, it's possible
690 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
691 * continuing. Amongst other possible reasons, this is to prevent
692 * mm_release()->clear_child_tid() from writing to a user-controlled
697 ptrace_event(PTRACE_EVENT_EXIT, code);
699 validate_creds_for_do_exit(tsk);
702 * We're taking recursive faults here in do_exit. Safest is to just
703 * leave this task alone and wait for reboot.
705 if (unlikely(tsk->flags & PF_EXITING)) {
706 pr_alert("Fixing recursive fault but reboot is needed!\n");
708 * We can do this unlocked here. The futex code uses
709 * this flag just to verify whether the pi state
710 * cleanup has been done or not. In the worst case it
711 * loops once more. We pretend that the cleanup was
712 * done as there is no way to return. Either the
713 * OWNER_DIED bit is set by now or we push the blocked
714 * task into the wait for ever nirwana as well.
716 tsk->flags |= PF_EXITPIDONE;
717 set_current_state(TASK_UNINTERRUPTIBLE);
721 exit_signals(tsk); /* sets PF_EXITING */
723 * tsk->flags are checked in the futex code to protect against
724 * an exiting task cleaning up the robust pi futexes.
727 raw_spin_unlock_wait(&tsk->pi_lock);
729 if (unlikely(in_atomic()))
730 pr_info("note: %s[%d] exited with preempt_count %d\n",
731 current->comm, task_pid_nr(current),
734 acct_update_integrals(tsk);
735 /* sync mm's RSS info before statistics gathering */
737 sync_mm_rss(tsk->mm);
738 group_dead = atomic_dec_and_test(&tsk->signal->live);
740 hrtimer_cancel(&tsk->signal->real_timer);
741 exit_itimers(tsk->signal);
743 setmax_mm_hiwater_rss(&tsk->signal->maxrss, tsk->mm);
745 acct_collect(code, group_dead);
750 tsk->exit_code = code;
751 taskstats_exit(tsk, group_dead);
757 trace_sched_process_exit(tsk);
764 disassociate_ctty(1);
765 exit_task_namespaces(tsk);
770 * Flush inherited counters to the parent - before the parent
771 * gets woken up by child-exit notifications.
773 * because of cgroup mode, must be called before cgroup_exit()
775 perf_event_exit_task(tsk);
779 module_put(task_thread_info(tsk)->exec_domain->module);
782 * FIXME: do that only when needed, using sched_exit tracepoint
784 flush_ptrace_hw_breakpoint(tsk);
786 TASKS_RCU(tasks_rcu_i = __srcu_read_lock(&tasks_rcu_exit_srcu));
787 exit_notify(tsk, group_dead);
788 proc_exit_connector(tsk);
791 mpol_put(tsk->mempolicy);
792 tsk->mempolicy = NULL;
796 if (unlikely(current->pi_state_cache))
797 kfree(current->pi_state_cache);
800 * Make sure we are holding no locks:
802 debug_check_no_locks_held();
804 * We can do this unlocked here. The futex code uses this flag
805 * just to verify whether the pi state cleanup has been done
806 * or not. In the worst case it loops once more.
808 tsk->flags |= PF_EXITPIDONE;
811 exit_io_context(tsk);
813 if (tsk->splice_pipe)
814 free_pipe_info(tsk->splice_pipe);
816 if (tsk->task_frag.page)
817 put_page(tsk->task_frag.page);
819 validate_creds_for_do_exit(tsk);
824 __this_cpu_add(dirty_throttle_leaks, tsk->nr_dirtied);
826 TASKS_RCU(__srcu_read_unlock(&tasks_rcu_exit_srcu, tasks_rcu_i));
829 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
830 * when the following two conditions become true.
831 * - There is race condition of mmap_sem (It is acquired by
833 * - SMI occurs before setting TASK_RUNINNG.
834 * (or hypervisor of virtual machine switches to other guest)
835 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
837 * To avoid it, we have to wait for releasing tsk->pi_lock which
838 * is held by try_to_wake_up()
841 raw_spin_unlock_wait(&tsk->pi_lock);
843 /* causes final put_task_struct in finish_task_switch(). */
844 tsk->state = TASK_DEAD;
845 tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */
848 /* Avoid "noreturn function does return". */
850 cpu_relax(); /* For when BUG is null */
852 EXPORT_SYMBOL_GPL(do_exit);
854 void complete_and_exit(struct completion *comp, long code)
861 EXPORT_SYMBOL(complete_and_exit);
863 SYSCALL_DEFINE1(exit, int, error_code)
865 do_exit((error_code&0xff)<<8);
869 * Take down every thread in the group. This is called by fatal signals
870 * as well as by sys_exit_group (below).
873 do_group_exit(int exit_code)
875 struct signal_struct *sig = current->signal;
877 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
879 if (signal_group_exit(sig))
880 exit_code = sig->group_exit_code;
881 else if (!thread_group_empty(current)) {
882 struct sighand_struct *const sighand = current->sighand;
884 spin_lock_irq(&sighand->siglock);
885 if (signal_group_exit(sig))
886 /* Another thread got here before we took the lock. */
887 exit_code = sig->group_exit_code;
889 sig->group_exit_code = exit_code;
890 sig->flags = SIGNAL_GROUP_EXIT;
891 zap_other_threads(current);
893 spin_unlock_irq(&sighand->siglock);
901 * this kills every thread in the thread group. Note that any externally
902 * wait4()-ing process will get the correct exit code - even if this
903 * thread is not the thread group leader.
905 SYSCALL_DEFINE1(exit_group, int, error_code)
907 do_group_exit((error_code & 0xff) << 8);
913 enum pid_type wo_type;
917 struct siginfo __user *wo_info;
919 struct rusage __user *wo_rusage;
921 wait_queue_t child_wait;
926 struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
928 if (type != PIDTYPE_PID)
929 task = task->group_leader;
930 return task->pids[type].pid;
933 static int eligible_pid(struct wait_opts *wo, struct task_struct *p)
935 return wo->wo_type == PIDTYPE_MAX ||
936 task_pid_type(p, wo->wo_type) == wo->wo_pid;
939 static int eligible_child(struct wait_opts *wo, struct task_struct *p)
941 if (!eligible_pid(wo, p))
943 /* Wait for all children (clone and not) if __WALL is set;
944 * otherwise, wait for clone children *only* if __WCLONE is
945 * set; otherwise, wait for non-clone children *only*. (Note:
946 * A "clone" child here is one that reports to its parent
947 * using a signal other than SIGCHLD.) */
948 if (((p->exit_signal != SIGCHLD) ^ !!(wo->wo_flags & __WCLONE))
949 && !(wo->wo_flags & __WALL))
955 static int wait_noreap_copyout(struct wait_opts *wo, struct task_struct *p,
956 pid_t pid, uid_t uid, int why, int status)
958 struct siginfo __user *infop;
959 int retval = wo->wo_rusage
960 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
966 retval = put_user(SIGCHLD, &infop->si_signo);
968 retval = put_user(0, &infop->si_errno);
970 retval = put_user((short)why, &infop->si_code);
972 retval = put_user(pid, &infop->si_pid);
974 retval = put_user(uid, &infop->si_uid);
976 retval = put_user(status, &infop->si_status);
984 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
985 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
986 * the lock and this task is uninteresting. If we return nonzero, we have
987 * released the lock and the system call should return.
989 static int wait_task_zombie(struct wait_opts *wo, struct task_struct *p)
991 int state, retval, status;
992 pid_t pid = task_pid_vnr(p);
993 uid_t uid = from_kuid_munged(current_user_ns(), task_uid(p));
994 struct siginfo __user *infop;
996 if (!likely(wo->wo_flags & WEXITED))
999 if (unlikely(wo->wo_flags & WNOWAIT)) {
1000 int exit_code = p->exit_code;
1004 read_unlock(&tasklist_lock);
1005 sched_annotate_sleep();
1007 if ((exit_code & 0x7f) == 0) {
1009 status = exit_code >> 8;
1011 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1012 status = exit_code & 0x7f;
1014 return wait_noreap_copyout(wo, p, pid, uid, why, status);
1017 * Move the task's state to DEAD/TRACE, only one thread can do this.
1019 state = (ptrace_reparented(p) && thread_group_leader(p)) ?
1020 EXIT_TRACE : EXIT_DEAD;
1021 if (cmpxchg(&p->exit_state, EXIT_ZOMBIE, state) != EXIT_ZOMBIE)
1024 * We own this thread, nobody else can reap it.
1026 read_unlock(&tasklist_lock);
1027 sched_annotate_sleep();
1030 * Check thread_group_leader() to exclude the traced sub-threads.
1032 if (state == EXIT_DEAD && thread_group_leader(p)) {
1033 struct signal_struct *sig = p->signal;
1034 struct signal_struct *psig = current->signal;
1035 unsigned long maxrss;
1036 cputime_t tgutime, tgstime;
1039 * The resource counters for the group leader are in its
1040 * own task_struct. Those for dead threads in the group
1041 * are in its signal_struct, as are those for the child
1042 * processes it has previously reaped. All these
1043 * accumulate in the parent's signal_struct c* fields.
1045 * We don't bother to take a lock here to protect these
1046 * p->signal fields because the whole thread group is dead
1047 * and nobody can change them.
1049 * psig->stats_lock also protects us from our sub-theads
1050 * which can reap other children at the same time. Until
1051 * we change k_getrusage()-like users to rely on this lock
1052 * we have to take ->siglock as well.
1054 * We use thread_group_cputime_adjusted() to get times for
1055 * the thread group, which consolidates times for all threads
1056 * in the group including the group leader.
1058 thread_group_cputime_adjusted(p, &tgutime, &tgstime);
1059 spin_lock_irq(¤t->sighand->siglock);
1060 write_seqlock(&psig->stats_lock);
1061 psig->cutime += tgutime + sig->cutime;
1062 psig->cstime += tgstime + sig->cstime;
1063 psig->cgtime += task_gtime(p) + sig->gtime + sig->cgtime;
1065 p->min_flt + sig->min_flt + sig->cmin_flt;
1067 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1069 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1071 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1073 task_io_get_inblock(p) +
1074 sig->inblock + sig->cinblock;
1076 task_io_get_oublock(p) +
1077 sig->oublock + sig->coublock;
1078 maxrss = max(sig->maxrss, sig->cmaxrss);
1079 if (psig->cmaxrss < maxrss)
1080 psig->cmaxrss = maxrss;
1081 task_io_accounting_add(&psig->ioac, &p->ioac);
1082 task_io_accounting_add(&psig->ioac, &sig->ioac);
1083 write_sequnlock(&psig->stats_lock);
1084 spin_unlock_irq(¤t->sighand->siglock);
1087 retval = wo->wo_rusage
1088 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1089 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1090 ? p->signal->group_exit_code : p->exit_code;
1091 if (!retval && wo->wo_stat)
1092 retval = put_user(status, wo->wo_stat);
1094 infop = wo->wo_info;
1095 if (!retval && infop)
1096 retval = put_user(SIGCHLD, &infop->si_signo);
1097 if (!retval && infop)
1098 retval = put_user(0, &infop->si_errno);
1099 if (!retval && infop) {
1102 if ((status & 0x7f) == 0) {
1106 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1109 retval = put_user((short)why, &infop->si_code);
1111 retval = put_user(status, &infop->si_status);
1113 if (!retval && infop)
1114 retval = put_user(pid, &infop->si_pid);
1115 if (!retval && infop)
1116 retval = put_user(uid, &infop->si_uid);
1120 if (state == EXIT_TRACE) {
1121 write_lock_irq(&tasklist_lock);
1122 /* We dropped tasklist, ptracer could die and untrace */
1125 /* If parent wants a zombie, don't release it now */
1126 state = EXIT_ZOMBIE;
1127 if (do_notify_parent(p, p->exit_signal))
1129 p->exit_state = state;
1130 write_unlock_irq(&tasklist_lock);
1132 if (state == EXIT_DEAD)
1138 static int *task_stopped_code(struct task_struct *p, bool ptrace)
1141 if (task_is_stopped_or_traced(p) &&
1142 !(p->jobctl & JOBCTL_LISTENING))
1143 return &p->exit_code;
1145 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1146 return &p->signal->group_exit_code;
1152 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1154 * @ptrace: is the wait for ptrace
1155 * @p: task to wait for
1157 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1160 * read_lock(&tasklist_lock), which is released if return value is
1161 * non-zero. Also, grabs and releases @p->sighand->siglock.
1164 * 0 if wait condition didn't exist and search for other wait conditions
1165 * should continue. Non-zero return, -errno on failure and @p's pid on
1166 * success, implies that tasklist_lock is released and wait condition
1167 * search should terminate.
1169 static int wait_task_stopped(struct wait_opts *wo,
1170 int ptrace, struct task_struct *p)
1172 struct siginfo __user *infop;
1173 int retval, exit_code, *p_code, why;
1174 uid_t uid = 0; /* unneeded, required by compiler */
1178 * Traditionally we see ptrace'd stopped tasks regardless of options.
1180 if (!ptrace && !(wo->wo_flags & WUNTRACED))
1183 if (!task_stopped_code(p, ptrace))
1187 spin_lock_irq(&p->sighand->siglock);
1189 p_code = task_stopped_code(p, ptrace);
1190 if (unlikely(!p_code))
1193 exit_code = *p_code;
1197 if (!unlikely(wo->wo_flags & WNOWAIT))
1200 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1202 spin_unlock_irq(&p->sighand->siglock);
1207 * Now we are pretty sure this task is interesting.
1208 * Make sure it doesn't get reaped out from under us while we
1209 * give up the lock and then examine it below. We don't want to
1210 * keep holding onto the tasklist_lock while we call getrusage and
1211 * possibly take page faults for user memory.
1214 pid = task_pid_vnr(p);
1215 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1216 read_unlock(&tasklist_lock);
1217 sched_annotate_sleep();
1219 if (unlikely(wo->wo_flags & WNOWAIT))
1220 return wait_noreap_copyout(wo, p, pid, uid, why, exit_code);
1222 retval = wo->wo_rusage
1223 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1224 if (!retval && wo->wo_stat)
1225 retval = put_user((exit_code << 8) | 0x7f, wo->wo_stat);
1227 infop = wo->wo_info;
1228 if (!retval && infop)
1229 retval = put_user(SIGCHLD, &infop->si_signo);
1230 if (!retval && infop)
1231 retval = put_user(0, &infop->si_errno);
1232 if (!retval && infop)
1233 retval = put_user((short)why, &infop->si_code);
1234 if (!retval && infop)
1235 retval = put_user(exit_code, &infop->si_status);
1236 if (!retval && infop)
1237 retval = put_user(pid, &infop->si_pid);
1238 if (!retval && infop)
1239 retval = put_user(uid, &infop->si_uid);
1249 * Handle do_wait work for one task in a live, non-stopped state.
1250 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1251 * the lock and this task is uninteresting. If we return nonzero, we have
1252 * released the lock and the system call should return.
1254 static int wait_task_continued(struct wait_opts *wo, struct task_struct *p)
1260 if (!unlikely(wo->wo_flags & WCONTINUED))
1263 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1266 spin_lock_irq(&p->sighand->siglock);
1267 /* Re-check with the lock held. */
1268 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1269 spin_unlock_irq(&p->sighand->siglock);
1272 if (!unlikely(wo->wo_flags & WNOWAIT))
1273 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1274 uid = from_kuid_munged(current_user_ns(), task_uid(p));
1275 spin_unlock_irq(&p->sighand->siglock);
1277 pid = task_pid_vnr(p);
1279 read_unlock(&tasklist_lock);
1280 sched_annotate_sleep();
1283 retval = wo->wo_rusage
1284 ? getrusage(p, RUSAGE_BOTH, wo->wo_rusage) : 0;
1286 if (!retval && wo->wo_stat)
1287 retval = put_user(0xffff, wo->wo_stat);
1291 retval = wait_noreap_copyout(wo, p, pid, uid,
1292 CLD_CONTINUED, SIGCONT);
1293 BUG_ON(retval == 0);
1300 * Consider @p for a wait by @parent.
1302 * -ECHILD should be in ->notask_error before the first call.
1303 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1304 * Returns zero if the search for a child should continue;
1305 * then ->notask_error is 0 if @p is an eligible child,
1306 * or another error from security_task_wait(), or still -ECHILD.
1308 static int wait_consider_task(struct wait_opts *wo, int ptrace,
1309 struct task_struct *p)
1313 if (unlikely(p->exit_state == EXIT_DEAD))
1316 ret = eligible_child(wo, p);
1320 ret = security_task_wait(p);
1321 if (unlikely(ret < 0)) {
1323 * If we have not yet seen any eligible child,
1324 * then let this error code replace -ECHILD.
1325 * A permission error will give the user a clue
1326 * to look for security policy problems, rather
1327 * than for mysterious wait bugs.
1329 if (wo->notask_error)
1330 wo->notask_error = ret;
1334 if (unlikely(p->exit_state == EXIT_TRACE)) {
1336 * ptrace == 0 means we are the natural parent. In this case
1337 * we should clear notask_error, debugger will notify us.
1339 if (likely(!ptrace))
1340 wo->notask_error = 0;
1344 if (likely(!ptrace) && unlikely(p->ptrace)) {
1346 * If it is traced by its real parent's group, just pretend
1347 * the caller is ptrace_do_wait() and reap this child if it
1350 * This also hides group stop state from real parent; otherwise
1351 * a single stop can be reported twice as group and ptrace stop.
1352 * If a ptracer wants to distinguish these two events for its
1353 * own children it should create a separate process which takes
1354 * the role of real parent.
1356 if (!ptrace_reparented(p))
1361 if (p->exit_state == EXIT_ZOMBIE) {
1362 /* we don't reap group leaders with subthreads */
1363 if (!delay_group_leader(p)) {
1365 * A zombie ptracee is only visible to its ptracer.
1366 * Notification and reaping will be cascaded to the
1367 * real parent when the ptracer detaches.
1369 if (unlikely(ptrace) || likely(!p->ptrace))
1370 return wait_task_zombie(wo, p);
1374 * Allow access to stopped/continued state via zombie by
1375 * falling through. Clearing of notask_error is complex.
1379 * If WEXITED is set, notask_error should naturally be
1380 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1381 * so, if there are live subthreads, there are events to
1382 * wait for. If all subthreads are dead, it's still safe
1383 * to clear - this function will be called again in finite
1384 * amount time once all the subthreads are released and
1385 * will then return without clearing.
1389 * Stopped state is per-task and thus can't change once the
1390 * target task dies. Only continued and exited can happen.
1391 * Clear notask_error if WCONTINUED | WEXITED.
1393 if (likely(!ptrace) || (wo->wo_flags & (WCONTINUED | WEXITED)))
1394 wo->notask_error = 0;
1397 * @p is alive and it's gonna stop, continue or exit, so
1398 * there always is something to wait for.
1400 wo->notask_error = 0;
1404 * Wait for stopped. Depending on @ptrace, different stopped state
1405 * is used and the two don't interact with each other.
1407 ret = wait_task_stopped(wo, ptrace, p);
1412 * Wait for continued. There's only one continued state and the
1413 * ptracer can consume it which can confuse the real parent. Don't
1414 * use WCONTINUED from ptracer. You don't need or want it.
1416 return wait_task_continued(wo, p);
1420 * Do the work of do_wait() for one thread in the group, @tsk.
1422 * -ECHILD should be in ->notask_error before the first call.
1423 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1424 * Returns zero if the search for a child should continue; then
1425 * ->notask_error is 0 if there were any eligible children,
1426 * or another error from security_task_wait(), or still -ECHILD.
1428 static int do_wait_thread(struct wait_opts *wo, struct task_struct *tsk)
1430 struct task_struct *p;
1432 list_for_each_entry(p, &tsk->children, sibling) {
1433 int ret = wait_consider_task(wo, 0, p);
1442 static int ptrace_do_wait(struct wait_opts *wo, struct task_struct *tsk)
1444 struct task_struct *p;
1446 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1447 int ret = wait_consider_task(wo, 1, p);
1456 static int child_wait_callback(wait_queue_t *wait, unsigned mode,
1457 int sync, void *key)
1459 struct wait_opts *wo = container_of(wait, struct wait_opts,
1461 struct task_struct *p = key;
1463 if (!eligible_pid(wo, p))
1466 if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent)
1469 return default_wake_function(wait, mode, sync, key);
1472 void __wake_up_parent(struct task_struct *p, struct task_struct *parent)
1474 __wake_up_sync_key(&parent->signal->wait_chldexit,
1475 TASK_INTERRUPTIBLE, 1, p);
1478 static long do_wait(struct wait_opts *wo)
1480 struct task_struct *tsk;
1483 trace_sched_process_wait(wo->wo_pid);
1485 init_waitqueue_func_entry(&wo->child_wait, child_wait_callback);
1486 wo->child_wait.private = current;
1487 add_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1490 * If there is nothing that can match our critiera just get out.
1491 * We will clear ->notask_error to zero if we see any child that
1492 * might later match our criteria, even if we are not able to reap
1495 wo->notask_error = -ECHILD;
1496 if ((wo->wo_type < PIDTYPE_MAX) &&
1497 (!wo->wo_pid || hlist_empty(&wo->wo_pid->tasks[wo->wo_type])))
1500 set_current_state(TASK_INTERRUPTIBLE);
1501 read_lock(&tasklist_lock);
1504 retval = do_wait_thread(wo, tsk);
1508 retval = ptrace_do_wait(wo, tsk);
1512 if (wo->wo_flags & __WNOTHREAD)
1514 } while_each_thread(current, tsk);
1515 read_unlock(&tasklist_lock);
1518 retval = wo->notask_error;
1519 if (!retval && !(wo->wo_flags & WNOHANG)) {
1520 retval = -ERESTARTSYS;
1521 if (!signal_pending(current)) {
1527 __set_current_state(TASK_RUNNING);
1528 remove_wait_queue(¤t->signal->wait_chldexit, &wo->child_wait);
1532 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1533 infop, int, options, struct rusage __user *, ru)
1535 struct wait_opts wo;
1536 struct pid *pid = NULL;
1540 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1542 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1555 type = PIDTYPE_PGID;
1563 if (type < PIDTYPE_MAX)
1564 pid = find_get_pid(upid);
1568 wo.wo_flags = options;
1578 * For a WNOHANG return, clear out all the fields
1579 * we would set so the user can easily tell the
1583 ret = put_user(0, &infop->si_signo);
1585 ret = put_user(0, &infop->si_errno);
1587 ret = put_user(0, &infop->si_code);
1589 ret = put_user(0, &infop->si_pid);
1591 ret = put_user(0, &infop->si_uid);
1593 ret = put_user(0, &infop->si_status);
1600 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1601 int, options, struct rusage __user *, ru)
1603 struct wait_opts wo;
1604 struct pid *pid = NULL;
1608 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1609 __WNOTHREAD|__WCLONE|__WALL))
1614 else if (upid < 0) {
1615 type = PIDTYPE_PGID;
1616 pid = find_get_pid(-upid);
1617 } else if (upid == 0) {
1618 type = PIDTYPE_PGID;
1619 pid = get_task_pid(current, PIDTYPE_PGID);
1620 } else /* upid > 0 */ {
1622 pid = find_get_pid(upid);
1627 wo.wo_flags = options | WEXITED;
1629 wo.wo_stat = stat_addr;
1637 #ifdef __ARCH_WANT_SYS_WAITPID
1640 * sys_waitpid() remains for compatibility. waitpid() should be
1641 * implemented by calling sys_wait4() from libc.a.
1643 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1645 return sys_wait4(pid, stat_addr, options, NULL);