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 * Determine if a process group is "orphaned", according to the POSIX
216 * definition in 2.2.2.52. Orphaned process groups are not to be affected
217 * by terminal-generated stop signals. Newly orphaned process groups are
218 * to receive a SIGHUP and a SIGCONT.
220 * "I ask you, have you ever known what it is to be an orphan?"
222 static int will_become_orphaned_pgrp(struct pid
*pgrp
,
223 struct task_struct
*ignored_task
)
225 struct task_struct
*p
;
227 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
228 if ((p
== ignored_task
) ||
229 (p
->exit_state
&& thread_group_empty(p
)) ||
230 is_global_init(p
->real_parent
))
233 if (task_pgrp(p
->real_parent
) != pgrp
&&
234 task_session(p
->real_parent
) == task_session(p
))
236 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
241 int is_current_pgrp_orphaned(void)
245 read_lock(&tasklist_lock
);
246 retval
= will_become_orphaned_pgrp(task_pgrp(current
), NULL
);
247 read_unlock(&tasklist_lock
);
252 static bool has_stopped_jobs(struct pid
*pgrp
)
254 struct task_struct
*p
;
256 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
257 if (p
->signal
->flags
& SIGNAL_STOP_STOPPED
)
259 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
265 * Check to see if any process groups have become orphaned as
266 * a result of our exiting, and if they have any stopped jobs,
267 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
270 kill_orphaned_pgrp(struct task_struct
*tsk
, struct task_struct
*parent
)
272 struct pid
*pgrp
= task_pgrp(tsk
);
273 struct task_struct
*ignored_task
= tsk
;
276 /* exit: our father is in a different pgrp than
277 * we are and we were the only connection outside.
279 parent
= tsk
->real_parent
;
281 /* reparent: our child is in a different pgrp than
282 * we are, and it was the only connection outside.
286 if (task_pgrp(parent
) != pgrp
&&
287 task_session(parent
) == task_session(tsk
) &&
288 will_become_orphaned_pgrp(pgrp
, ignored_task
) &&
289 has_stopped_jobs(pgrp
)) {
290 __kill_pgrp_info(SIGHUP
, SEND_SIG_PRIV
, pgrp
);
291 __kill_pgrp_info(SIGCONT
, SEND_SIG_PRIV
, pgrp
);
297 * A task is exiting. If it owned this mm, find a new owner for the mm.
299 void mm_update_next_owner(struct mm_struct
*mm
)
301 struct task_struct
*c
, *g
, *p
= current
;
305 * If the exiting or execing task is not the owner, it's
306 * someone else's problem.
311 * The current owner is exiting/execing and there are no other
312 * candidates. Do not leave the mm pointing to a possibly
313 * freed task structure.
315 if (atomic_read(&mm
->mm_users
) <= 1) {
320 read_lock(&tasklist_lock
);
322 * Search in the children
324 list_for_each_entry(c
, &p
->children
, sibling
) {
326 goto assign_new_owner
;
330 * Search in the siblings
332 list_for_each_entry(c
, &p
->real_parent
->children
, sibling
) {
334 goto assign_new_owner
;
338 * Search through everything else, we should not get here often.
340 for_each_process(g
) {
341 if (g
->flags
& PF_KTHREAD
)
343 for_each_thread(g
, c
) {
345 goto assign_new_owner
;
350 read_unlock(&tasklist_lock
);
352 * We found no owner yet mm_users > 1: this implies that we are
353 * most likely racing with swapoff (try_to_unuse()) or /proc or
354 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
363 * The task_lock protects c->mm from changing.
364 * We always want mm->owner->mm == mm
368 * Delay read_unlock() till we have the task_lock()
369 * to ensure that c does not slip away underneath us
371 read_unlock(&tasklist_lock
);
381 #endif /* CONFIG_MEMCG */
384 * Turn us into a lazy TLB process if we
387 static void exit_mm(struct task_struct
*tsk
)
389 struct mm_struct
*mm
= tsk
->mm
;
390 struct core_state
*core_state
;
397 * Serialize with any possible pending coredump.
398 * We must hold mmap_sem around checking core_state
399 * and clearing tsk->mm. The core-inducing thread
400 * will increment ->nr_threads for each thread in the
401 * group with ->mm != NULL.
403 down_read(&mm
->mmap_sem
);
404 core_state
= mm
->core_state
;
406 struct core_thread self
;
408 up_read(&mm
->mmap_sem
);
411 self
.next
= xchg(&core_state
->dumper
.next
, &self
);
413 * Implies mb(), the result of xchg() must be visible
414 * to core_state->dumper.
416 if (atomic_dec_and_test(&core_state
->nr_threads
))
417 complete(&core_state
->startup
);
420 set_task_state(tsk
, TASK_UNINTERRUPTIBLE
);
421 if (!self
.task
) /* see coredump_finish() */
423 freezable_schedule();
425 __set_task_state(tsk
, TASK_RUNNING
);
426 down_read(&mm
->mmap_sem
);
428 atomic_inc(&mm
->mm_count
);
429 BUG_ON(mm
!= tsk
->active_mm
);
430 /* more a memory barrier than a real lock */
433 up_read(&mm
->mmap_sem
);
434 enter_lazy_tlb(mm
, current
);
436 mm_update_next_owner(mm
);
438 if (test_thread_flag(TIF_MEMDIE
))
442 static struct task_struct
*find_alive_thread(struct task_struct
*p
)
444 struct task_struct
*t
;
446 for_each_thread(p
, t
) {
447 if (!(t
->flags
& PF_EXITING
))
453 static struct task_struct
*find_child_reaper(struct task_struct
*father
)
454 __releases(&tasklist_lock
)
455 __acquires(&tasklist_lock
)
457 struct pid_namespace
*pid_ns
= task_active_pid_ns(father
);
458 struct task_struct
*reaper
= pid_ns
->child_reaper
;
460 if (likely(reaper
!= father
))
463 reaper
= find_alive_thread(father
);
465 pid_ns
->child_reaper
= reaper
;
469 write_unlock_irq(&tasklist_lock
);
470 if (unlikely(pid_ns
== &init_pid_ns
)) {
471 panic("Attempted to kill init! exitcode=0x%08x\n",
472 father
->signal
->group_exit_code
?: father
->exit_code
);
474 zap_pid_ns_processes(pid_ns
);
475 write_lock_irq(&tasklist_lock
);
481 * When we die, we re-parent all our children, and try to:
482 * 1. give them to another thread in our thread group, if such a member exists
483 * 2. give it to the first ancestor process which prctl'd itself as a
484 * child_subreaper for its children (like a service manager)
485 * 3. give it to the init process (PID 1) in our pid namespace
487 static struct task_struct
*find_new_reaper(struct task_struct
*father
,
488 struct task_struct
*child_reaper
)
490 struct task_struct
*thread
, *reaper
;
492 thread
= find_alive_thread(father
);
496 if (father
->signal
->has_child_subreaper
) {
498 * Find the first ->is_child_subreaper ancestor in our pid_ns.
499 * We start from father to ensure we can not look into another
500 * namespace, this is safe because all its threads are dead.
502 for (reaper
= father
;
503 !same_thread_group(reaper
, child_reaper
);
504 reaper
= reaper
->real_parent
) {
505 /* call_usermodehelper() descendants need this check */
506 if (reaper
== &init_task
)
508 if (!reaper
->signal
->is_child_subreaper
)
510 thread
= find_alive_thread(reaper
);
520 * Any that need to be release_task'd are put on the @dead list.
522 static void reparent_leader(struct task_struct
*father
, struct task_struct
*p
,
523 struct list_head
*dead
)
525 if (unlikely(p
->exit_state
== EXIT_DEAD
))
528 /* We don't want people slaying init. */
529 p
->exit_signal
= SIGCHLD
;
531 /* If it has exited notify the new parent about this child's death. */
533 p
->exit_state
== EXIT_ZOMBIE
&& thread_group_empty(p
)) {
534 if (do_notify_parent(p
, p
->exit_signal
)) {
535 p
->exit_state
= EXIT_DEAD
;
536 list_add(&p
->ptrace_entry
, dead
);
540 kill_orphaned_pgrp(p
, father
);
544 * This does two things:
546 * A. Make init inherit all the child processes
547 * B. Check to see if any process groups have become orphaned
548 * as a result of our exiting, and if they have any stopped
549 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
551 static void forget_original_parent(struct task_struct
*father
,
552 struct list_head
*dead
)
554 struct task_struct
*p
, *t
, *reaper
;
556 if (unlikely(!list_empty(&father
->ptraced
)))
557 exit_ptrace(father
, dead
);
559 /* Can drop and reacquire tasklist_lock */
560 reaper
= find_child_reaper(father
);
561 if (list_empty(&father
->children
))
564 reaper
= find_new_reaper(father
, reaper
);
565 list_for_each_entry(p
, &father
->children
, sibling
) {
566 for_each_thread(p
, t
) {
567 t
->real_parent
= reaper
;
568 BUG_ON((!t
->ptrace
) != (t
->parent
== father
));
569 if (likely(!t
->ptrace
))
570 t
->parent
= t
->real_parent
;
571 if (t
->pdeath_signal
)
572 group_send_sig_info(t
->pdeath_signal
,
576 * If this is a threaded reparent there is no need to
577 * notify anyone anything has happened.
579 if (!same_thread_group(reaper
, father
))
580 reparent_leader(father
, p
, dead
);
582 list_splice_tail_init(&father
->children
, &reaper
->children
);
586 * Send signals to all our closest relatives so that they know
587 * to properly mourn us..
589 static void exit_notify(struct task_struct
*tsk
, int group_dead
)
592 struct task_struct
*p
, *n
;
595 write_lock_irq(&tasklist_lock
);
596 forget_original_parent(tsk
, &dead
);
599 kill_orphaned_pgrp(tsk
->group_leader
, NULL
);
601 if (unlikely(tsk
->ptrace
)) {
602 int sig
= thread_group_leader(tsk
) &&
603 thread_group_empty(tsk
) &&
604 !ptrace_reparented(tsk
) ?
605 tsk
->exit_signal
: SIGCHLD
;
606 autoreap
= do_notify_parent(tsk
, sig
);
607 } else if (thread_group_leader(tsk
)) {
608 autoreap
= thread_group_empty(tsk
) &&
609 do_notify_parent(tsk
, tsk
->exit_signal
);
614 tsk
->exit_state
= autoreap
? EXIT_DEAD
: EXIT_ZOMBIE
;
615 if (tsk
->exit_state
== EXIT_DEAD
)
616 list_add(&tsk
->ptrace_entry
, &dead
);
618 /* mt-exec, de_thread() is waiting for group leader */
619 if (unlikely(tsk
->signal
->notify_count
< 0))
620 wake_up_process(tsk
->signal
->group_exit_task
);
621 write_unlock_irq(&tasklist_lock
);
623 list_for_each_entry_safe(p
, n
, &dead
, ptrace_entry
) {
624 list_del_init(&p
->ptrace_entry
);
629 #ifdef CONFIG_DEBUG_STACK_USAGE
630 static void check_stack_usage(void)
632 static DEFINE_SPINLOCK(low_water_lock
);
633 static int lowest_to_date
= THREAD_SIZE
;
636 free
= stack_not_used(current
);
638 if (free
>= lowest_to_date
)
641 spin_lock(&low_water_lock
);
642 if (free
< lowest_to_date
) {
643 pr_warn("%s (%d) used greatest stack depth: %lu bytes left\n",
644 current
->comm
, task_pid_nr(current
), free
);
645 lowest_to_date
= free
;
647 spin_unlock(&low_water_lock
);
650 static inline void check_stack_usage(void) {}
653 void do_exit(long code
)
655 struct task_struct
*tsk
= current
;
657 TASKS_RCU(int tasks_rcu_i
);
659 profile_task_exit(tsk
);
661 WARN_ON(blk_needs_flush_plug(tsk
));
663 if (unlikely(in_interrupt()))
664 panic("Aiee, killing interrupt handler!");
665 if (unlikely(!tsk
->pid
))
666 panic("Attempted to kill the idle task!");
669 * If do_exit is called because this processes oopsed, it's possible
670 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
671 * continuing. Amongst other possible reasons, this is to prevent
672 * mm_release()->clear_child_tid() from writing to a user-controlled
677 ptrace_event(PTRACE_EVENT_EXIT
, code
);
679 validate_creds_for_do_exit(tsk
);
682 * We're taking recursive faults here in do_exit. Safest is to just
683 * leave this task alone and wait for reboot.
685 if (unlikely(tsk
->flags
& PF_EXITING
)) {
686 pr_alert("Fixing recursive fault but reboot is needed!\n");
688 * We can do this unlocked here. The futex code uses
689 * this flag just to verify whether the pi state
690 * cleanup has been done or not. In the worst case it
691 * loops once more. We pretend that the cleanup was
692 * done as there is no way to return. Either the
693 * OWNER_DIED bit is set by now or we push the blocked
694 * task into the wait for ever nirwana as well.
696 tsk
->flags
|= PF_EXITPIDONE
;
697 set_current_state(TASK_UNINTERRUPTIBLE
);
701 exit_signals(tsk
); /* sets PF_EXITING */
703 * tsk->flags are checked in the futex code to protect against
704 * an exiting task cleaning up the robust pi futexes.
707 raw_spin_unlock_wait(&tsk
->pi_lock
);
709 if (unlikely(in_atomic()))
710 pr_info("note: %s[%d] exited with preempt_count %d\n",
711 current
->comm
, task_pid_nr(current
),
714 acct_update_integrals(tsk
);
715 /* sync mm's RSS info before statistics gathering */
717 sync_mm_rss(tsk
->mm
);
718 group_dead
= atomic_dec_and_test(&tsk
->signal
->live
);
720 hrtimer_cancel(&tsk
->signal
->real_timer
);
721 exit_itimers(tsk
->signal
);
723 setmax_mm_hiwater_rss(&tsk
->signal
->maxrss
, tsk
->mm
);
725 acct_collect(code
, group_dead
);
730 tsk
->exit_code
= code
;
731 taskstats_exit(tsk
, group_dead
);
737 trace_sched_process_exit(tsk
);
744 disassociate_ctty(1);
745 exit_task_namespaces(tsk
);
750 * Flush inherited counters to the parent - before the parent
751 * gets woken up by child-exit notifications.
753 * because of cgroup mode, must be called before cgroup_exit()
755 perf_event_exit_task(tsk
);
760 * FIXME: do that only when needed, using sched_exit tracepoint
762 flush_ptrace_hw_breakpoint(tsk
);
764 TASKS_RCU(tasks_rcu_i
= __srcu_read_lock(&tasks_rcu_exit_srcu
));
765 exit_notify(tsk
, group_dead
);
766 proc_exit_connector(tsk
);
769 mpol_put(tsk
->mempolicy
);
770 tsk
->mempolicy
= NULL
;
774 if (unlikely(current
->pi_state_cache
))
775 kfree(current
->pi_state_cache
);
778 * Make sure we are holding no locks:
780 debug_check_no_locks_held();
782 * We can do this unlocked here. The futex code uses this flag
783 * just to verify whether the pi state cleanup has been done
784 * or not. In the worst case it loops once more.
786 tsk
->flags
|= PF_EXITPIDONE
;
789 exit_io_context(tsk
);
791 if (tsk
->splice_pipe
)
792 free_pipe_info(tsk
->splice_pipe
);
794 if (tsk
->task_frag
.page
)
795 put_page(tsk
->task_frag
.page
);
797 validate_creds_for_do_exit(tsk
);
802 __this_cpu_add(dirty_throttle_leaks
, tsk
->nr_dirtied
);
804 TASKS_RCU(__srcu_read_unlock(&tasks_rcu_exit_srcu
, tasks_rcu_i
));
807 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
808 * when the following two conditions become true.
809 * - There is race condition of mmap_sem (It is acquired by
811 * - SMI occurs before setting TASK_RUNINNG.
812 * (or hypervisor of virtual machine switches to other guest)
813 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
815 * To avoid it, we have to wait for releasing tsk->pi_lock which
816 * is held by try_to_wake_up()
819 raw_spin_unlock_wait(&tsk
->pi_lock
);
821 /* causes final put_task_struct in finish_task_switch(). */
822 tsk
->state
= TASK_DEAD
;
823 tsk
->flags
|= PF_NOFREEZE
; /* tell freezer to ignore us */
826 /* Avoid "noreturn function does return". */
828 cpu_relax(); /* For when BUG is null */
830 EXPORT_SYMBOL_GPL(do_exit
);
832 void complete_and_exit(struct completion
*comp
, long code
)
839 EXPORT_SYMBOL(complete_and_exit
);
841 SYSCALL_DEFINE1(exit
, int, error_code
)
843 do_exit((error_code
&0xff)<<8);
847 * Take down every thread in the group. This is called by fatal signals
848 * as well as by sys_exit_group (below).
851 do_group_exit(int exit_code
)
853 struct signal_struct
*sig
= current
->signal
;
855 BUG_ON(exit_code
& 0x80); /* core dumps don't get here */
857 if (signal_group_exit(sig
))
858 exit_code
= sig
->group_exit_code
;
859 else if (!thread_group_empty(current
)) {
860 struct sighand_struct
*const sighand
= current
->sighand
;
862 spin_lock_irq(&sighand
->siglock
);
863 if (signal_group_exit(sig
))
864 /* Another thread got here before we took the lock. */
865 exit_code
= sig
->group_exit_code
;
867 sig
->group_exit_code
= exit_code
;
868 sig
->flags
= SIGNAL_GROUP_EXIT
;
869 zap_other_threads(current
);
871 spin_unlock_irq(&sighand
->siglock
);
879 * this kills every thread in the thread group. Note that any externally
880 * wait4()-ing process will get the correct exit code - even if this
881 * thread is not the thread group leader.
883 SYSCALL_DEFINE1(exit_group
, int, error_code
)
885 do_group_exit((error_code
& 0xff) << 8);
891 enum pid_type wo_type
;
895 struct siginfo __user
*wo_info
;
897 struct rusage __user
*wo_rusage
;
899 wait_queue_t child_wait
;
904 struct pid
*task_pid_type(struct task_struct
*task
, enum pid_type type
)
906 if (type
!= PIDTYPE_PID
)
907 task
= task
->group_leader
;
908 return task
->pids
[type
].pid
;
911 static int eligible_pid(struct wait_opts
*wo
, struct task_struct
*p
)
913 return wo
->wo_type
== PIDTYPE_MAX
||
914 task_pid_type(p
, wo
->wo_type
) == wo
->wo_pid
;
917 static int eligible_child(struct wait_opts
*wo
, struct task_struct
*p
)
919 if (!eligible_pid(wo
, p
))
921 /* Wait for all children (clone and not) if __WALL is set;
922 * otherwise, wait for clone children *only* if __WCLONE is
923 * set; otherwise, wait for non-clone children *only*. (Note:
924 * A "clone" child here is one that reports to its parent
925 * using a signal other than SIGCHLD.) */
926 if (((p
->exit_signal
!= SIGCHLD
) ^ !!(wo
->wo_flags
& __WCLONE
))
927 && !(wo
->wo_flags
& __WALL
))
933 static int wait_noreap_copyout(struct wait_opts
*wo
, struct task_struct
*p
,
934 pid_t pid
, uid_t uid
, int why
, int status
)
936 struct siginfo __user
*infop
;
937 int retval
= wo
->wo_rusage
938 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
944 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
946 retval
= put_user(0, &infop
->si_errno
);
948 retval
= put_user((short)why
, &infop
->si_code
);
950 retval
= put_user(pid
, &infop
->si_pid
);
952 retval
= put_user(uid
, &infop
->si_uid
);
954 retval
= put_user(status
, &infop
->si_status
);
962 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
963 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
964 * the lock and this task is uninteresting. If we return nonzero, we have
965 * released the lock and the system call should return.
967 static int wait_task_zombie(struct wait_opts
*wo
, struct task_struct
*p
)
969 int state
, retval
, status
;
970 pid_t pid
= task_pid_vnr(p
);
971 uid_t uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
972 struct siginfo __user
*infop
;
974 if (!likely(wo
->wo_flags
& WEXITED
))
977 if (unlikely(wo
->wo_flags
& WNOWAIT
)) {
978 int exit_code
= p
->exit_code
;
982 read_unlock(&tasklist_lock
);
983 sched_annotate_sleep();
985 if ((exit_code
& 0x7f) == 0) {
987 status
= exit_code
>> 8;
989 why
= (exit_code
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
990 status
= exit_code
& 0x7f;
992 return wait_noreap_copyout(wo
, p
, pid
, uid
, why
, status
);
995 * Move the task's state to DEAD/TRACE, only one thread can do this.
997 state
= (ptrace_reparented(p
) && thread_group_leader(p
)) ?
998 EXIT_TRACE
: EXIT_DEAD
;
999 if (cmpxchg(&p
->exit_state
, EXIT_ZOMBIE
, state
) != EXIT_ZOMBIE
)
1002 * We own this thread, nobody else can reap it.
1004 read_unlock(&tasklist_lock
);
1005 sched_annotate_sleep();
1008 * Check thread_group_leader() to exclude the traced sub-threads.
1010 if (state
== EXIT_DEAD
&& thread_group_leader(p
)) {
1011 struct signal_struct
*sig
= p
->signal
;
1012 struct signal_struct
*psig
= current
->signal
;
1013 unsigned long maxrss
;
1014 cputime_t tgutime
, tgstime
;
1017 * The resource counters for the group leader are in its
1018 * own task_struct. Those for dead threads in the group
1019 * are in its signal_struct, as are those for the child
1020 * processes it has previously reaped. All these
1021 * accumulate in the parent's signal_struct c* fields.
1023 * We don't bother to take a lock here to protect these
1024 * p->signal fields because the whole thread group is dead
1025 * and nobody can change them.
1027 * psig->stats_lock also protects us from our sub-theads
1028 * which can reap other children at the same time. Until
1029 * we change k_getrusage()-like users to rely on this lock
1030 * we have to take ->siglock as well.
1032 * We use thread_group_cputime_adjusted() to get times for
1033 * the thread group, which consolidates times for all threads
1034 * in the group including the group leader.
1036 thread_group_cputime_adjusted(p
, &tgutime
, &tgstime
);
1037 spin_lock_irq(¤t
->sighand
->siglock
);
1038 write_seqlock(&psig
->stats_lock
);
1039 psig
->cutime
+= tgutime
+ sig
->cutime
;
1040 psig
->cstime
+= tgstime
+ sig
->cstime
;
1041 psig
->cgtime
+= task_gtime(p
) + sig
->gtime
+ sig
->cgtime
;
1043 p
->min_flt
+ sig
->min_flt
+ sig
->cmin_flt
;
1045 p
->maj_flt
+ sig
->maj_flt
+ sig
->cmaj_flt
;
1047 p
->nvcsw
+ sig
->nvcsw
+ sig
->cnvcsw
;
1049 p
->nivcsw
+ sig
->nivcsw
+ sig
->cnivcsw
;
1051 task_io_get_inblock(p
) +
1052 sig
->inblock
+ sig
->cinblock
;
1054 task_io_get_oublock(p
) +
1055 sig
->oublock
+ sig
->coublock
;
1056 maxrss
= max(sig
->maxrss
, sig
->cmaxrss
);
1057 if (psig
->cmaxrss
< maxrss
)
1058 psig
->cmaxrss
= maxrss
;
1059 task_io_accounting_add(&psig
->ioac
, &p
->ioac
);
1060 task_io_accounting_add(&psig
->ioac
, &sig
->ioac
);
1061 write_sequnlock(&psig
->stats_lock
);
1062 spin_unlock_irq(¤t
->sighand
->siglock
);
1065 retval
= wo
->wo_rusage
1066 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
1067 status
= (p
->signal
->flags
& SIGNAL_GROUP_EXIT
)
1068 ? p
->signal
->group_exit_code
: p
->exit_code
;
1069 if (!retval
&& wo
->wo_stat
)
1070 retval
= put_user(status
, wo
->wo_stat
);
1072 infop
= wo
->wo_info
;
1073 if (!retval
&& infop
)
1074 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1075 if (!retval
&& infop
)
1076 retval
= put_user(0, &infop
->si_errno
);
1077 if (!retval
&& infop
) {
1080 if ((status
& 0x7f) == 0) {
1084 why
= (status
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
1087 retval
= put_user((short)why
, &infop
->si_code
);
1089 retval
= put_user(status
, &infop
->si_status
);
1091 if (!retval
&& infop
)
1092 retval
= put_user(pid
, &infop
->si_pid
);
1093 if (!retval
&& infop
)
1094 retval
= put_user(uid
, &infop
->si_uid
);
1098 if (state
== EXIT_TRACE
) {
1099 write_lock_irq(&tasklist_lock
);
1100 /* We dropped tasklist, ptracer could die and untrace */
1103 /* If parent wants a zombie, don't release it now */
1104 state
= EXIT_ZOMBIE
;
1105 if (do_notify_parent(p
, p
->exit_signal
))
1107 p
->exit_state
= state
;
1108 write_unlock_irq(&tasklist_lock
);
1110 if (state
== EXIT_DEAD
)
1116 static int *task_stopped_code(struct task_struct
*p
, bool ptrace
)
1119 if (task_is_stopped_or_traced(p
) &&
1120 !(p
->jobctl
& JOBCTL_LISTENING
))
1121 return &p
->exit_code
;
1123 if (p
->signal
->flags
& SIGNAL_STOP_STOPPED
)
1124 return &p
->signal
->group_exit_code
;
1130 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1132 * @ptrace: is the wait for ptrace
1133 * @p: task to wait for
1135 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1138 * read_lock(&tasklist_lock), which is released if return value is
1139 * non-zero. Also, grabs and releases @p->sighand->siglock.
1142 * 0 if wait condition didn't exist and search for other wait conditions
1143 * should continue. Non-zero return, -errno on failure and @p's pid on
1144 * success, implies that tasklist_lock is released and wait condition
1145 * search should terminate.
1147 static int wait_task_stopped(struct wait_opts
*wo
,
1148 int ptrace
, struct task_struct
*p
)
1150 struct siginfo __user
*infop
;
1151 int retval
, exit_code
, *p_code
, why
;
1152 uid_t uid
= 0; /* unneeded, required by compiler */
1156 * Traditionally we see ptrace'd stopped tasks regardless of options.
1158 if (!ptrace
&& !(wo
->wo_flags
& WUNTRACED
))
1161 if (!task_stopped_code(p
, ptrace
))
1165 spin_lock_irq(&p
->sighand
->siglock
);
1167 p_code
= task_stopped_code(p
, ptrace
);
1168 if (unlikely(!p_code
))
1171 exit_code
= *p_code
;
1175 if (!unlikely(wo
->wo_flags
& WNOWAIT
))
1178 uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
1180 spin_unlock_irq(&p
->sighand
->siglock
);
1185 * Now we are pretty sure this task is interesting.
1186 * Make sure it doesn't get reaped out from under us while we
1187 * give up the lock and then examine it below. We don't want to
1188 * keep holding onto the tasklist_lock while we call getrusage and
1189 * possibly take page faults for user memory.
1192 pid
= task_pid_vnr(p
);
1193 why
= ptrace
? CLD_TRAPPED
: CLD_STOPPED
;
1194 read_unlock(&tasklist_lock
);
1195 sched_annotate_sleep();
1197 if (unlikely(wo
->wo_flags
& WNOWAIT
))
1198 return wait_noreap_copyout(wo
, p
, pid
, uid
, why
, exit_code
);
1200 retval
= wo
->wo_rusage
1201 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
1202 if (!retval
&& wo
->wo_stat
)
1203 retval
= put_user((exit_code
<< 8) | 0x7f, wo
->wo_stat
);
1205 infop
= wo
->wo_info
;
1206 if (!retval
&& infop
)
1207 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1208 if (!retval
&& infop
)
1209 retval
= put_user(0, &infop
->si_errno
);
1210 if (!retval
&& infop
)
1211 retval
= put_user((short)why
, &infop
->si_code
);
1212 if (!retval
&& infop
)
1213 retval
= put_user(exit_code
, &infop
->si_status
);
1214 if (!retval
&& infop
)
1215 retval
= put_user(pid
, &infop
->si_pid
);
1216 if (!retval
&& infop
)
1217 retval
= put_user(uid
, &infop
->si_uid
);
1227 * Handle do_wait work for one task in a live, non-stopped state.
1228 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1229 * the lock and this task is uninteresting. If we return nonzero, we have
1230 * released the lock and the system call should return.
1232 static int wait_task_continued(struct wait_opts
*wo
, struct task_struct
*p
)
1238 if (!unlikely(wo
->wo_flags
& WCONTINUED
))
1241 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
))
1244 spin_lock_irq(&p
->sighand
->siglock
);
1245 /* Re-check with the lock held. */
1246 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
)) {
1247 spin_unlock_irq(&p
->sighand
->siglock
);
1250 if (!unlikely(wo
->wo_flags
& WNOWAIT
))
1251 p
->signal
->flags
&= ~SIGNAL_STOP_CONTINUED
;
1252 uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
1253 spin_unlock_irq(&p
->sighand
->siglock
);
1255 pid
= task_pid_vnr(p
);
1257 read_unlock(&tasklist_lock
);
1258 sched_annotate_sleep();
1261 retval
= wo
->wo_rusage
1262 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
1264 if (!retval
&& wo
->wo_stat
)
1265 retval
= put_user(0xffff, wo
->wo_stat
);
1269 retval
= wait_noreap_copyout(wo
, p
, pid
, uid
,
1270 CLD_CONTINUED
, SIGCONT
);
1271 BUG_ON(retval
== 0);
1278 * Consider @p for a wait by @parent.
1280 * -ECHILD should be in ->notask_error before the first call.
1281 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1282 * Returns zero if the search for a child should continue;
1283 * then ->notask_error is 0 if @p is an eligible child,
1284 * or another error from security_task_wait(), or still -ECHILD.
1286 static int wait_consider_task(struct wait_opts
*wo
, int ptrace
,
1287 struct task_struct
*p
)
1290 * We can race with wait_task_zombie() from another thread.
1291 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1292 * can't confuse the checks below.
1294 int exit_state
= ACCESS_ONCE(p
->exit_state
);
1297 if (unlikely(exit_state
== EXIT_DEAD
))
1300 ret
= eligible_child(wo
, p
);
1304 ret
= security_task_wait(p
);
1305 if (unlikely(ret
< 0)) {
1307 * If we have not yet seen any eligible child,
1308 * then let this error code replace -ECHILD.
1309 * A permission error will give the user a clue
1310 * to look for security policy problems, rather
1311 * than for mysterious wait bugs.
1313 if (wo
->notask_error
)
1314 wo
->notask_error
= ret
;
1318 if (unlikely(exit_state
== EXIT_TRACE
)) {
1320 * ptrace == 0 means we are the natural parent. In this case
1321 * we should clear notask_error, debugger will notify us.
1323 if (likely(!ptrace
))
1324 wo
->notask_error
= 0;
1328 if (likely(!ptrace
) && unlikely(p
->ptrace
)) {
1330 * If it is traced by its real parent's group, just pretend
1331 * the caller is ptrace_do_wait() and reap this child if it
1334 * This also hides group stop state from real parent; otherwise
1335 * a single stop can be reported twice as group and ptrace stop.
1336 * If a ptracer wants to distinguish these two events for its
1337 * own children it should create a separate process which takes
1338 * the role of real parent.
1340 if (!ptrace_reparented(p
))
1345 if (exit_state
== EXIT_ZOMBIE
) {
1346 /* we don't reap group leaders with subthreads */
1347 if (!delay_group_leader(p
)) {
1349 * A zombie ptracee is only visible to its ptracer.
1350 * Notification and reaping will be cascaded to the
1351 * real parent when the ptracer detaches.
1353 if (unlikely(ptrace
) || likely(!p
->ptrace
))
1354 return wait_task_zombie(wo
, p
);
1358 * Allow access to stopped/continued state via zombie by
1359 * falling through. Clearing of notask_error is complex.
1363 * If WEXITED is set, notask_error should naturally be
1364 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1365 * so, if there are live subthreads, there are events to
1366 * wait for. If all subthreads are dead, it's still safe
1367 * to clear - this function will be called again in finite
1368 * amount time once all the subthreads are released and
1369 * will then return without clearing.
1373 * Stopped state is per-task and thus can't change once the
1374 * target task dies. Only continued and exited can happen.
1375 * Clear notask_error if WCONTINUED | WEXITED.
1377 if (likely(!ptrace
) || (wo
->wo_flags
& (WCONTINUED
| WEXITED
)))
1378 wo
->notask_error
= 0;
1381 * @p is alive and it's gonna stop, continue or exit, so
1382 * there always is something to wait for.
1384 wo
->notask_error
= 0;
1388 * Wait for stopped. Depending on @ptrace, different stopped state
1389 * is used and the two don't interact with each other.
1391 ret
= wait_task_stopped(wo
, ptrace
, p
);
1396 * Wait for continued. There's only one continued state and the
1397 * ptracer can consume it which can confuse the real parent. Don't
1398 * use WCONTINUED from ptracer. You don't need or want it.
1400 return wait_task_continued(wo
, p
);
1404 * Do the work of do_wait() for one thread in the group, @tsk.
1406 * -ECHILD should be in ->notask_error before the first call.
1407 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1408 * Returns zero if the search for a child should continue; then
1409 * ->notask_error is 0 if there were any eligible children,
1410 * or another error from security_task_wait(), or still -ECHILD.
1412 static int do_wait_thread(struct wait_opts
*wo
, struct task_struct
*tsk
)
1414 struct task_struct
*p
;
1416 list_for_each_entry(p
, &tsk
->children
, sibling
) {
1417 int ret
= wait_consider_task(wo
, 0, p
);
1426 static int ptrace_do_wait(struct wait_opts
*wo
, struct task_struct
*tsk
)
1428 struct task_struct
*p
;
1430 list_for_each_entry(p
, &tsk
->ptraced
, ptrace_entry
) {
1431 int ret
= wait_consider_task(wo
, 1, p
);
1440 static int child_wait_callback(wait_queue_t
*wait
, unsigned mode
,
1441 int sync
, void *key
)
1443 struct wait_opts
*wo
= container_of(wait
, struct wait_opts
,
1445 struct task_struct
*p
= key
;
1447 if (!eligible_pid(wo
, p
))
1450 if ((wo
->wo_flags
& __WNOTHREAD
) && wait
->private != p
->parent
)
1453 return default_wake_function(wait
, mode
, sync
, key
);
1456 void __wake_up_parent(struct task_struct
*p
, struct task_struct
*parent
)
1458 __wake_up_sync_key(&parent
->signal
->wait_chldexit
,
1459 TASK_INTERRUPTIBLE
, 1, p
);
1462 static long do_wait(struct wait_opts
*wo
)
1464 struct task_struct
*tsk
;
1467 trace_sched_process_wait(wo
->wo_pid
);
1469 init_waitqueue_func_entry(&wo
->child_wait
, child_wait_callback
);
1470 wo
->child_wait
.private = current
;
1471 add_wait_queue(¤t
->signal
->wait_chldexit
, &wo
->child_wait
);
1474 * If there is nothing that can match our critiera just get out.
1475 * We will clear ->notask_error to zero if we see any child that
1476 * might later match our criteria, even if we are not able to reap
1479 wo
->notask_error
= -ECHILD
;
1480 if ((wo
->wo_type
< PIDTYPE_MAX
) &&
1481 (!wo
->wo_pid
|| hlist_empty(&wo
->wo_pid
->tasks
[wo
->wo_type
])))
1484 set_current_state(TASK_INTERRUPTIBLE
);
1485 read_lock(&tasklist_lock
);
1488 retval
= do_wait_thread(wo
, tsk
);
1492 retval
= ptrace_do_wait(wo
, tsk
);
1496 if (wo
->wo_flags
& __WNOTHREAD
)
1498 } while_each_thread(current
, tsk
);
1499 read_unlock(&tasklist_lock
);
1502 retval
= wo
->notask_error
;
1503 if (!retval
&& !(wo
->wo_flags
& WNOHANG
)) {
1504 retval
= -ERESTARTSYS
;
1505 if (!signal_pending(current
)) {
1511 __set_current_state(TASK_RUNNING
);
1512 remove_wait_queue(¤t
->signal
->wait_chldexit
, &wo
->child_wait
);
1516 SYSCALL_DEFINE5(waitid
, int, which
, pid_t
, upid
, struct siginfo __user
*,
1517 infop
, int, options
, struct rusage __user
*, ru
)
1519 struct wait_opts wo
;
1520 struct pid
*pid
= NULL
;
1524 if (options
& ~(WNOHANG
|WNOWAIT
|WEXITED
|WSTOPPED
|WCONTINUED
))
1526 if (!(options
& (WEXITED
|WSTOPPED
|WCONTINUED
)))
1539 type
= PIDTYPE_PGID
;
1547 if (type
< PIDTYPE_MAX
)
1548 pid
= find_get_pid(upid
);
1552 wo
.wo_flags
= options
;
1562 * For a WNOHANG return, clear out all the fields
1563 * we would set so the user can easily tell the
1567 ret
= put_user(0, &infop
->si_signo
);
1569 ret
= put_user(0, &infop
->si_errno
);
1571 ret
= put_user(0, &infop
->si_code
);
1573 ret
= put_user(0, &infop
->si_pid
);
1575 ret
= put_user(0, &infop
->si_uid
);
1577 ret
= put_user(0, &infop
->si_status
);
1584 SYSCALL_DEFINE4(wait4
, pid_t
, upid
, int __user
*, stat_addr
,
1585 int, options
, struct rusage __user
*, ru
)
1587 struct wait_opts wo
;
1588 struct pid
*pid
= NULL
;
1592 if (options
& ~(WNOHANG
|WUNTRACED
|WCONTINUED
|
1593 __WNOTHREAD
|__WCLONE
|__WALL
))
1598 else if (upid
< 0) {
1599 type
= PIDTYPE_PGID
;
1600 pid
= find_get_pid(-upid
);
1601 } else if (upid
== 0) {
1602 type
= PIDTYPE_PGID
;
1603 pid
= get_task_pid(current
, PIDTYPE_PGID
);
1604 } else /* upid > 0 */ {
1606 pid
= find_get_pid(upid
);
1611 wo
.wo_flags
= options
| WEXITED
;
1613 wo
.wo_stat
= stat_addr
;
1621 #ifdef __ARCH_WANT_SYS_WAITPID
1624 * sys_waitpid() remains for compatibility. waitpid() should be
1625 * implemented by calling sys_wait4() from libc.a.
1627 SYSCALL_DEFINE3(waitpid
, pid_t
, pid
, int __user
*, stat_addr
, int, options
)
1629 return sys_wait4(pid
, stat_addr
, options
, NULL
);
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