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 __unhash_process(struct task_struct
*p
, bool group_dead
)
65 detach_pid(p
, PIDTYPE_PID
);
67 detach_pid(p
, PIDTYPE_PGID
);
68 detach_pid(p
, PIDTYPE_SID
);
70 list_del_rcu(&p
->tasks
);
71 list_del_init(&p
->sibling
);
72 __this_cpu_dec(process_counts
);
74 list_del_rcu(&p
->thread_group
);
75 list_del_rcu(&p
->thread_node
);
79 * This function expects the tasklist_lock write-locked.
81 static void __exit_signal(struct task_struct
*tsk
)
83 struct signal_struct
*sig
= tsk
->signal
;
84 bool group_dead
= thread_group_leader(tsk
);
85 struct sighand_struct
*sighand
;
86 struct tty_struct
*uninitialized_var(tty
);
87 cputime_t utime
, stime
;
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
);
119 * Accumulate here the counters for all threads as they die. We could
120 * skip the group leader because it is the last user of signal_struct,
121 * but we want to avoid the race with thread_group_cputime() which can
122 * see the empty ->thread_head list.
124 task_cputime(tsk
, &utime
, &stime
);
125 write_seqlock(&sig
->stats_lock
);
128 sig
->gtime
+= task_gtime(tsk
);
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
;
138 __unhash_process(tsk
, group_dead
);
139 write_sequnlock(&sig
->stats_lock
);
142 * Do this under ->siglock, we can race with another thread
143 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
145 flush_sigqueue(&tsk
->pending
);
147 spin_unlock(&sighand
->siglock
);
149 __cleanup_sighand(sighand
);
150 clear_tsk_thread_flag(tsk
, TIF_SIGPENDING
);
152 flush_sigqueue(&sig
->shared_pending
);
157 static void delayed_put_task_struct(struct rcu_head
*rhp
)
159 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
161 perf_event_delayed_put(tsk
);
162 trace_sched_process_free(tsk
);
163 put_task_struct(tsk
);
167 void release_task(struct task_struct
*p
)
169 struct task_struct
*leader
;
172 /* don't need to get the RCU readlock here - the process is dead and
173 * can't be modifying its own credentials. But shut RCU-lockdep up */
175 atomic_dec(&__task_cred(p
)->user
->processes
);
180 write_lock_irq(&tasklist_lock
);
181 ptrace_release_task(p
);
185 * If we are the last non-leader member of the thread
186 * group, and the leader is zombie, then notify the
187 * group leader's parent process. (if it wants notification.)
190 leader
= p
->group_leader
;
191 if (leader
!= p
&& thread_group_empty(leader
)
192 && 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 * Determine if a process group is "orphaned", according to the POSIX
214 * definition in 2.2.2.52. Orphaned process groups are not to be affected
215 * by terminal-generated stop signals. Newly orphaned process groups are
216 * to receive a SIGHUP and a SIGCONT.
218 * "I ask you, have you ever known what it is to be an orphan?"
220 static int will_become_orphaned_pgrp(struct pid
*pgrp
,
221 struct task_struct
*ignored_task
)
223 struct task_struct
*p
;
225 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
226 if ((p
== ignored_task
) ||
227 (p
->exit_state
&& thread_group_empty(p
)) ||
228 is_global_init(p
->real_parent
))
231 if (task_pgrp(p
->real_parent
) != pgrp
&&
232 task_session(p
->real_parent
) == task_session(p
))
234 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
239 int is_current_pgrp_orphaned(void)
243 read_lock(&tasklist_lock
);
244 retval
= will_become_orphaned_pgrp(task_pgrp(current
), NULL
);
245 read_unlock(&tasklist_lock
);
250 static bool has_stopped_jobs(struct pid
*pgrp
)
252 struct task_struct
*p
;
254 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
255 if (p
->signal
->flags
& SIGNAL_STOP_STOPPED
)
257 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
263 * Check to see if any process groups have become orphaned as
264 * a result of our exiting, and if they have any stopped jobs,
265 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
268 kill_orphaned_pgrp(struct task_struct
*tsk
, struct task_struct
*parent
)
270 struct pid
*pgrp
= task_pgrp(tsk
);
271 struct task_struct
*ignored_task
= tsk
;
274 /* exit: our father is in a different pgrp than
275 * we are and we were the only connection outside.
277 parent
= tsk
->real_parent
;
279 /* reparent: our child is in a different pgrp than
280 * we are, and it was the only connection outside.
284 if (task_pgrp(parent
) != pgrp
&&
285 task_session(parent
) == task_session(tsk
) &&
286 will_become_orphaned_pgrp(pgrp
, ignored_task
) &&
287 has_stopped_jobs(pgrp
)) {
288 __kill_pgrp_info(SIGHUP
, SEND_SIG_PRIV
, pgrp
);
289 __kill_pgrp_info(SIGCONT
, SEND_SIG_PRIV
, pgrp
);
295 * A task is exiting. If it owned this mm, find a new owner for the mm.
297 void mm_update_next_owner(struct mm_struct
*mm
)
299 struct task_struct
*c
, *g
, *p
= current
;
303 * If the exiting or execing task is not the owner, it's
304 * someone else's problem.
309 * The current owner is exiting/execing and there are no other
310 * candidates. Do not leave the mm pointing to a possibly
311 * freed task structure.
313 if (atomic_read(&mm
->mm_users
) <= 1) {
318 read_lock(&tasklist_lock
);
320 * Search in the children
322 list_for_each_entry(c
, &p
->children
, sibling
) {
324 goto assign_new_owner
;
328 * Search in the siblings
330 list_for_each_entry(c
, &p
->real_parent
->children
, sibling
) {
332 goto assign_new_owner
;
336 * Search through everything else, we should not get here often.
338 for_each_process(g
) {
339 if (g
->flags
& PF_KTHREAD
)
341 for_each_thread(g
, c
) {
343 goto assign_new_owner
;
348 read_unlock(&tasklist_lock
);
350 * We found no owner yet mm_users > 1: this implies that we are
351 * most likely racing with swapoff (try_to_unuse()) or /proc or
352 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
361 * The task_lock protects c->mm from changing.
362 * We always want mm->owner->mm == mm
366 * Delay read_unlock() till we have the task_lock()
367 * to ensure that c does not slip away underneath us
369 read_unlock(&tasklist_lock
);
379 #endif /* CONFIG_MEMCG */
382 * Turn us into a lazy TLB process if we
385 static void exit_mm(struct task_struct
*tsk
)
387 struct mm_struct
*mm
= tsk
->mm
;
388 struct core_state
*core_state
;
395 * Serialize with any possible pending coredump.
396 * We must hold mmap_sem around checking core_state
397 * and clearing tsk->mm. The core-inducing thread
398 * will increment ->nr_threads for each thread in the
399 * group with ->mm != NULL.
401 down_read(&mm
->mmap_sem
);
402 core_state
= mm
->core_state
;
404 struct core_thread self
;
406 up_read(&mm
->mmap_sem
);
409 self
.next
= xchg(&core_state
->dumper
.next
, &self
);
411 * Implies mb(), the result of xchg() must be visible
412 * to core_state->dumper.
414 if (atomic_dec_and_test(&core_state
->nr_threads
))
415 complete(&core_state
->startup
);
418 set_task_state(tsk
, TASK_UNINTERRUPTIBLE
);
419 if (!self
.task
) /* see coredump_finish() */
421 freezable_schedule();
423 __set_task_state(tsk
, TASK_RUNNING
);
424 down_read(&mm
->mmap_sem
);
426 atomic_inc(&mm
->mm_count
);
427 BUG_ON(mm
!= tsk
->active_mm
);
428 /* more a memory barrier than a real lock */
431 up_read(&mm
->mmap_sem
);
432 enter_lazy_tlb(mm
, current
);
434 mm_update_next_owner(mm
);
436 if (test_thread_flag(TIF_MEMDIE
))
440 static struct task_struct
*find_alive_thread(struct task_struct
*p
)
442 struct task_struct
*t
;
444 for_each_thread(p
, t
) {
445 if (!(t
->flags
& PF_EXITING
))
451 static struct task_struct
*find_child_reaper(struct task_struct
*father
)
452 __releases(&tasklist_lock
)
453 __acquires(&tasklist_lock
)
455 struct pid_namespace
*pid_ns
= task_active_pid_ns(father
);
456 struct task_struct
*reaper
= pid_ns
->child_reaper
;
458 if (likely(reaper
!= father
))
461 reaper
= find_alive_thread(father
);
463 pid_ns
->child_reaper
= reaper
;
467 write_unlock_irq(&tasklist_lock
);
468 if (unlikely(pid_ns
== &init_pid_ns
)) {
469 panic("Attempted to kill init! exitcode=0x%08x\n",
470 father
->signal
->group_exit_code
?: father
->exit_code
);
472 zap_pid_ns_processes(pid_ns
);
473 write_lock_irq(&tasklist_lock
);
479 * When we die, we re-parent all our children, and try to:
480 * 1. give them to another thread in our thread group, if such a member exists
481 * 2. give it to the first ancestor process which prctl'd itself as a
482 * child_subreaper for its children (like a service manager)
483 * 3. give it to the init process (PID 1) in our pid namespace
485 static struct task_struct
*find_new_reaper(struct task_struct
*father
,
486 struct task_struct
*child_reaper
)
488 struct task_struct
*thread
, *reaper
;
490 thread
= find_alive_thread(father
);
494 if (father
->signal
->has_child_subreaper
) {
496 * Find the first ->is_child_subreaper ancestor in our pid_ns.
497 * We start from father to ensure we can not look into another
498 * namespace, this is safe because all its threads are dead.
500 for (reaper
= father
;
501 !same_thread_group(reaper
, child_reaper
);
502 reaper
= reaper
->real_parent
) {
503 /* call_usermodehelper() descendants need this check */
504 if (reaper
== &init_task
)
506 if (!reaper
->signal
->is_child_subreaper
)
508 thread
= find_alive_thread(reaper
);
518 * Any that need to be release_task'd are put on the @dead list.
520 static void reparent_leader(struct task_struct
*father
, struct task_struct
*p
,
521 struct list_head
*dead
)
523 if (unlikely(p
->exit_state
== EXIT_DEAD
))
526 /* We don't want people slaying init. */
527 p
->exit_signal
= SIGCHLD
;
529 /* If it has exited notify the new parent about this child's death. */
531 p
->exit_state
== EXIT_ZOMBIE
&& thread_group_empty(p
)) {
532 if (do_notify_parent(p
, p
->exit_signal
)) {
533 p
->exit_state
= EXIT_DEAD
;
534 list_add(&p
->ptrace_entry
, dead
);
538 kill_orphaned_pgrp(p
, father
);
542 * This does two things:
544 * A. Make init inherit all the child processes
545 * B. Check to see if any process groups have become orphaned
546 * as a result of our exiting, and if they have any stopped
547 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
549 static void forget_original_parent(struct task_struct
*father
,
550 struct list_head
*dead
)
552 struct task_struct
*p
, *t
, *reaper
;
554 if (unlikely(!list_empty(&father
->ptraced
)))
555 exit_ptrace(father
, dead
);
557 /* Can drop and reacquire tasklist_lock */
558 reaper
= find_child_reaper(father
);
559 if (list_empty(&father
->children
))
562 reaper
= find_new_reaper(father
, reaper
);
563 list_for_each_entry(p
, &father
->children
, sibling
) {
564 for_each_thread(p
, t
) {
565 t
->real_parent
= reaper
;
566 BUG_ON((!t
->ptrace
) != (t
->parent
== father
));
567 if (likely(!t
->ptrace
))
568 t
->parent
= t
->real_parent
;
569 if (t
->pdeath_signal
)
570 group_send_sig_info(t
->pdeath_signal
,
574 * If this is a threaded reparent there is no need to
575 * notify anyone anything has happened.
577 if (!same_thread_group(reaper
, father
))
578 reparent_leader(father
, p
, dead
);
580 list_splice_tail_init(&father
->children
, &reaper
->children
);
584 * Send signals to all our closest relatives so that they know
585 * to properly mourn us..
587 static void exit_notify(struct task_struct
*tsk
, int group_dead
)
590 struct task_struct
*p
, *n
;
593 write_lock_irq(&tasklist_lock
);
594 forget_original_parent(tsk
, &dead
);
597 kill_orphaned_pgrp(tsk
->group_leader
, NULL
);
599 if (unlikely(tsk
->ptrace
)) {
600 int sig
= thread_group_leader(tsk
) &&
601 thread_group_empty(tsk
) &&
602 !ptrace_reparented(tsk
) ?
603 tsk
->exit_signal
: SIGCHLD
;
604 autoreap
= do_notify_parent(tsk
, sig
);
605 } else if (thread_group_leader(tsk
)) {
606 autoreap
= thread_group_empty(tsk
) &&
607 do_notify_parent(tsk
, tsk
->exit_signal
);
612 tsk
->exit_state
= autoreap
? EXIT_DEAD
: EXIT_ZOMBIE
;
613 if (tsk
->exit_state
== EXIT_DEAD
)
614 list_add(&tsk
->ptrace_entry
, &dead
);
616 /* mt-exec, de_thread() is waiting for group leader */
617 if (unlikely(tsk
->signal
->notify_count
< 0))
618 wake_up_process(tsk
->signal
->group_exit_task
);
619 write_unlock_irq(&tasklist_lock
);
621 list_for_each_entry_safe(p
, n
, &dead
, ptrace_entry
) {
622 list_del_init(&p
->ptrace_entry
);
627 #ifdef CONFIG_DEBUG_STACK_USAGE
628 static void check_stack_usage(void)
630 static DEFINE_SPINLOCK(low_water_lock
);
631 static int lowest_to_date
= THREAD_SIZE
;
634 free
= stack_not_used(current
);
636 if (free
>= lowest_to_date
)
639 spin_lock(&low_water_lock
);
640 if (free
< lowest_to_date
) {
641 pr_warn("%s (%d) used greatest stack depth: %lu bytes left\n",
642 current
->comm
, task_pid_nr(current
), free
);
643 lowest_to_date
= free
;
645 spin_unlock(&low_water_lock
);
648 static inline void check_stack_usage(void) {}
651 void do_exit(long code
)
653 struct task_struct
*tsk
= current
;
655 TASKS_RCU(int tasks_rcu_i
);
657 profile_task_exit(tsk
);
659 WARN_ON(blk_needs_flush_plug(tsk
));
661 if (unlikely(in_interrupt()))
662 panic("Aiee, killing interrupt handler!");
663 if (unlikely(!tsk
->pid
))
664 panic("Attempted to kill the idle task!");
667 * If do_exit is called because this processes oopsed, it's possible
668 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
669 * continuing. Amongst other possible reasons, this is to prevent
670 * mm_release()->clear_child_tid() from writing to a user-controlled
675 ptrace_event(PTRACE_EVENT_EXIT
, code
);
677 validate_creds_for_do_exit(tsk
);
680 * We're taking recursive faults here in do_exit. Safest is to just
681 * leave this task alone and wait for reboot.
683 if (unlikely(tsk
->flags
& PF_EXITING
)) {
684 pr_alert("Fixing recursive fault but reboot is needed!\n");
686 * We can do this unlocked here. The futex code uses
687 * this flag just to verify whether the pi state
688 * cleanup has been done or not. In the worst case it
689 * loops once more. We pretend that the cleanup was
690 * done as there is no way to return. Either the
691 * OWNER_DIED bit is set by now or we push the blocked
692 * task into the wait for ever nirwana as well.
694 tsk
->flags
|= PF_EXITPIDONE
;
695 set_current_state(TASK_UNINTERRUPTIBLE
);
699 exit_signals(tsk
); /* sets PF_EXITING */
701 * tsk->flags are checked in the futex code to protect against
702 * an exiting task cleaning up the robust pi futexes.
705 raw_spin_unlock_wait(&tsk
->pi_lock
);
707 if (unlikely(in_atomic())) {
708 pr_info("note: %s[%d] exited with preempt_count %d\n",
709 current
->comm
, task_pid_nr(current
),
711 preempt_count_set(PREEMPT_ENABLED
);
714 /* sync mm's RSS info before statistics gathering */
716 sync_mm_rss(tsk
->mm
);
717 acct_update_integrals(tsk
);
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(preempt_disable());
765 TASKS_RCU(tasks_rcu_i
= __srcu_read_lock(&tasks_rcu_exit_srcu
));
766 TASKS_RCU(preempt_enable());
767 exit_notify(tsk
, group_dead
);
768 proc_exit_connector(tsk
);
771 mpol_put(tsk
->mempolicy
);
772 tsk
->mempolicy
= NULL
;
776 if (unlikely(current
->pi_state_cache
))
777 kfree(current
->pi_state_cache
);
780 * Make sure we are holding no locks:
782 debug_check_no_locks_held();
784 * We can do this unlocked here. The futex code uses this flag
785 * just to verify whether the pi state cleanup has been done
786 * or not. In the worst case it loops once more.
788 tsk
->flags
|= PF_EXITPIDONE
;
791 exit_io_context(tsk
);
793 if (tsk
->splice_pipe
)
794 free_pipe_info(tsk
->splice_pipe
);
796 if (tsk
->task_frag
.page
)
797 put_page(tsk
->task_frag
.page
);
799 validate_creds_for_do_exit(tsk
);
804 __this_cpu_add(dirty_throttle_leaks
, tsk
->nr_dirtied
);
806 TASKS_RCU(__srcu_read_unlock(&tasks_rcu_exit_srcu
, tasks_rcu_i
));
809 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
810 * when the following two conditions become true.
811 * - There is race condition of mmap_sem (It is acquired by
813 * - SMI occurs before setting TASK_RUNINNG.
814 * (or hypervisor of virtual machine switches to other guest)
815 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
817 * To avoid it, we have to wait for releasing tsk->pi_lock which
818 * is held by try_to_wake_up()
821 raw_spin_unlock_wait(&tsk
->pi_lock
);
823 /* causes final put_task_struct in finish_task_switch(). */
824 tsk
->state
= TASK_DEAD
;
825 tsk
->flags
|= PF_NOFREEZE
; /* tell freezer to ignore us */
828 /* Avoid "noreturn function does return". */
830 cpu_relax(); /* For when BUG is null */
832 EXPORT_SYMBOL_GPL(do_exit
);
834 void complete_and_exit(struct completion
*comp
, long code
)
841 EXPORT_SYMBOL(complete_and_exit
);
843 SYSCALL_DEFINE1(exit
, int, error_code
)
845 do_exit((error_code
&0xff)<<8);
849 * Take down every thread in the group. This is called by fatal signals
850 * as well as by sys_exit_group (below).
853 do_group_exit(int exit_code
)
855 struct signal_struct
*sig
= current
->signal
;
857 BUG_ON(exit_code
& 0x80); /* core dumps don't get here */
859 if (signal_group_exit(sig
))
860 exit_code
= sig
->group_exit_code
;
861 else if (!thread_group_empty(current
)) {
862 struct sighand_struct
*const sighand
= current
->sighand
;
864 spin_lock_irq(&sighand
->siglock
);
865 if (signal_group_exit(sig
))
866 /* Another thread got here before we took the lock. */
867 exit_code
= sig
->group_exit_code
;
869 sig
->group_exit_code
= exit_code
;
870 sig
->flags
= SIGNAL_GROUP_EXIT
;
871 zap_other_threads(current
);
873 spin_unlock_irq(&sighand
->siglock
);
881 * this kills every thread in the thread group. Note that any externally
882 * wait4()-ing process will get the correct exit code - even if this
883 * thread is not the thread group leader.
885 SYSCALL_DEFINE1(exit_group
, int, error_code
)
887 do_group_exit((error_code
& 0xff) << 8);
893 enum pid_type wo_type
;
897 struct siginfo __user
*wo_info
;
899 struct rusage __user
*wo_rusage
;
901 wait_queue_t child_wait
;
906 struct pid
*task_pid_type(struct task_struct
*task
, enum pid_type type
)
908 if (type
!= PIDTYPE_PID
)
909 task
= task
->group_leader
;
910 return task
->pids
[type
].pid
;
913 static int eligible_pid(struct wait_opts
*wo
, struct task_struct
*p
)
915 return wo
->wo_type
== PIDTYPE_MAX
||
916 task_pid_type(p
, wo
->wo_type
) == wo
->wo_pid
;
919 static int eligible_child(struct wait_opts
*wo
, struct task_struct
*p
)
921 if (!eligible_pid(wo
, p
))
923 /* Wait for all children (clone and not) if __WALL is set;
924 * otherwise, wait for clone children *only* if __WCLONE is
925 * set; otherwise, wait for non-clone children *only*. (Note:
926 * A "clone" child here is one that reports to its parent
927 * using a signal other than SIGCHLD.) */
928 if (((p
->exit_signal
!= SIGCHLD
) ^ !!(wo
->wo_flags
& __WCLONE
))
929 && !(wo
->wo_flags
& __WALL
))
935 static int wait_noreap_copyout(struct wait_opts
*wo
, struct task_struct
*p
,
936 pid_t pid
, uid_t uid
, int why
, int status
)
938 struct siginfo __user
*infop
;
939 int retval
= wo
->wo_rusage
940 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
946 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
948 retval
= put_user(0, &infop
->si_errno
);
950 retval
= put_user((short)why
, &infop
->si_code
);
952 retval
= put_user(pid
, &infop
->si_pid
);
954 retval
= put_user(uid
, &infop
->si_uid
);
956 retval
= put_user(status
, &infop
->si_status
);
964 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
965 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
966 * the lock and this task is uninteresting. If we return nonzero, we have
967 * released the lock and the system call should return.
969 static int wait_task_zombie(struct wait_opts
*wo
, struct task_struct
*p
)
971 int state
, retval
, status
;
972 pid_t pid
= task_pid_vnr(p
);
973 uid_t uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
974 struct siginfo __user
*infop
;
976 if (!likely(wo
->wo_flags
& WEXITED
))
979 if (unlikely(wo
->wo_flags
& WNOWAIT
)) {
980 int exit_code
= p
->exit_code
;
984 read_unlock(&tasklist_lock
);
985 sched_annotate_sleep();
987 if ((exit_code
& 0x7f) == 0) {
989 status
= exit_code
>> 8;
991 why
= (exit_code
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
992 status
= exit_code
& 0x7f;
994 return wait_noreap_copyout(wo
, p
, pid
, uid
, why
, status
);
997 * Move the task's state to DEAD/TRACE, only one thread can do this.
999 state
= (ptrace_reparented(p
) && thread_group_leader(p
)) ?
1000 EXIT_TRACE
: EXIT_DEAD
;
1001 if (cmpxchg(&p
->exit_state
, EXIT_ZOMBIE
, state
) != EXIT_ZOMBIE
)
1004 * We own this thread, nobody else can reap it.
1006 read_unlock(&tasklist_lock
);
1007 sched_annotate_sleep();
1010 * Check thread_group_leader() to exclude the traced sub-threads.
1012 if (state
== EXIT_DEAD
&& thread_group_leader(p
)) {
1013 struct signal_struct
*sig
= p
->signal
;
1014 struct signal_struct
*psig
= current
->signal
;
1015 unsigned long maxrss
;
1016 cputime_t tgutime
, tgstime
;
1019 * The resource counters for the group leader are in its
1020 * own task_struct. Those for dead threads in the group
1021 * are in its signal_struct, as are those for the child
1022 * processes it has previously reaped. All these
1023 * accumulate in the parent's signal_struct c* fields.
1025 * We don't bother to take a lock here to protect these
1026 * p->signal fields because the whole thread group is dead
1027 * and nobody can change them.
1029 * psig->stats_lock also protects us from our sub-theads
1030 * which can reap other children at the same time. Until
1031 * we change k_getrusage()-like users to rely on this lock
1032 * we have to take ->siglock as well.
1034 * We use thread_group_cputime_adjusted() to get times for
1035 * the thread group, which consolidates times for all threads
1036 * in the group including the group leader.
1038 thread_group_cputime_adjusted(p
, &tgutime
, &tgstime
);
1039 spin_lock_irq(¤t
->sighand
->siglock
);
1040 write_seqlock(&psig
->stats_lock
);
1041 psig
->cutime
+= tgutime
+ sig
->cutime
;
1042 psig
->cstime
+= tgstime
+ sig
->cstime
;
1043 psig
->cgtime
+= task_gtime(p
) + sig
->gtime
+ sig
->cgtime
;
1045 p
->min_flt
+ sig
->min_flt
+ sig
->cmin_flt
;
1047 p
->maj_flt
+ sig
->maj_flt
+ sig
->cmaj_flt
;
1049 p
->nvcsw
+ sig
->nvcsw
+ sig
->cnvcsw
;
1051 p
->nivcsw
+ sig
->nivcsw
+ sig
->cnivcsw
;
1053 task_io_get_inblock(p
) +
1054 sig
->inblock
+ sig
->cinblock
;
1056 task_io_get_oublock(p
) +
1057 sig
->oublock
+ sig
->coublock
;
1058 maxrss
= max(sig
->maxrss
, sig
->cmaxrss
);
1059 if (psig
->cmaxrss
< maxrss
)
1060 psig
->cmaxrss
= maxrss
;
1061 task_io_accounting_add(&psig
->ioac
, &p
->ioac
);
1062 task_io_accounting_add(&psig
->ioac
, &sig
->ioac
);
1063 write_sequnlock(&psig
->stats_lock
);
1064 spin_unlock_irq(¤t
->sighand
->siglock
);
1067 retval
= wo
->wo_rusage
1068 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
1069 status
= (p
->signal
->flags
& SIGNAL_GROUP_EXIT
)
1070 ? p
->signal
->group_exit_code
: p
->exit_code
;
1071 if (!retval
&& wo
->wo_stat
)
1072 retval
= put_user(status
, wo
->wo_stat
);
1074 infop
= wo
->wo_info
;
1075 if (!retval
&& infop
)
1076 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1077 if (!retval
&& infop
)
1078 retval
= put_user(0, &infop
->si_errno
);
1079 if (!retval
&& infop
) {
1082 if ((status
& 0x7f) == 0) {
1086 why
= (status
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
1089 retval
= put_user((short)why
, &infop
->si_code
);
1091 retval
= put_user(status
, &infop
->si_status
);
1093 if (!retval
&& infop
)
1094 retval
= put_user(pid
, &infop
->si_pid
);
1095 if (!retval
&& infop
)
1096 retval
= put_user(uid
, &infop
->si_uid
);
1100 if (state
== EXIT_TRACE
) {
1101 write_lock_irq(&tasklist_lock
);
1102 /* We dropped tasklist, ptracer could die and untrace */
1105 /* If parent wants a zombie, don't release it now */
1106 state
= EXIT_ZOMBIE
;
1107 if (do_notify_parent(p
, p
->exit_signal
))
1109 p
->exit_state
= state
;
1110 write_unlock_irq(&tasklist_lock
);
1112 if (state
== EXIT_DEAD
)
1118 static int *task_stopped_code(struct task_struct
*p
, bool ptrace
)
1121 if (task_is_traced(p
) && !(p
->jobctl
& JOBCTL_LISTENING
))
1122 return &p
->exit_code
;
1124 if (p
->signal
->flags
& SIGNAL_STOP_STOPPED
)
1125 return &p
->signal
->group_exit_code
;
1131 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1133 * @ptrace: is the wait for ptrace
1134 * @p: task to wait for
1136 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1139 * read_lock(&tasklist_lock), which is released if return value is
1140 * non-zero. Also, grabs and releases @p->sighand->siglock.
1143 * 0 if wait condition didn't exist and search for other wait conditions
1144 * should continue. Non-zero return, -errno on failure and @p's pid on
1145 * success, implies that tasklist_lock is released and wait condition
1146 * search should terminate.
1148 static int wait_task_stopped(struct wait_opts
*wo
,
1149 int ptrace
, struct task_struct
*p
)
1151 struct siginfo __user
*infop
;
1152 int retval
, exit_code
, *p_code
, why
;
1153 uid_t uid
= 0; /* unneeded, required by compiler */
1157 * Traditionally we see ptrace'd stopped tasks regardless of options.
1159 if (!ptrace
&& !(wo
->wo_flags
& WUNTRACED
))
1162 if (!task_stopped_code(p
, ptrace
))
1166 spin_lock_irq(&p
->sighand
->siglock
);
1168 p_code
= task_stopped_code(p
, ptrace
);
1169 if (unlikely(!p_code
))
1172 exit_code
= *p_code
;
1176 if (!unlikely(wo
->wo_flags
& WNOWAIT
))
1179 uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
1181 spin_unlock_irq(&p
->sighand
->siglock
);
1186 * Now we are pretty sure this task is interesting.
1187 * Make sure it doesn't get reaped out from under us while we
1188 * give up the lock and then examine it below. We don't want to
1189 * keep holding onto the tasklist_lock while we call getrusage and
1190 * possibly take page faults for user memory.
1193 pid
= task_pid_vnr(p
);
1194 why
= ptrace
? CLD_TRAPPED
: CLD_STOPPED
;
1195 read_unlock(&tasklist_lock
);
1196 sched_annotate_sleep();
1198 if (unlikely(wo
->wo_flags
& WNOWAIT
))
1199 return wait_noreap_copyout(wo
, p
, pid
, uid
, why
, exit_code
);
1201 retval
= wo
->wo_rusage
1202 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
1203 if (!retval
&& wo
->wo_stat
)
1204 retval
= put_user((exit_code
<< 8) | 0x7f, wo
->wo_stat
);
1206 infop
= wo
->wo_info
;
1207 if (!retval
&& infop
)
1208 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1209 if (!retval
&& infop
)
1210 retval
= put_user(0, &infop
->si_errno
);
1211 if (!retval
&& infop
)
1212 retval
= put_user((short)why
, &infop
->si_code
);
1213 if (!retval
&& infop
)
1214 retval
= put_user(exit_code
, &infop
->si_status
);
1215 if (!retval
&& infop
)
1216 retval
= put_user(pid
, &infop
->si_pid
);
1217 if (!retval
&& infop
)
1218 retval
= put_user(uid
, &infop
->si_uid
);
1228 * Handle do_wait work for one task in a live, non-stopped state.
1229 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1230 * the lock and this task is uninteresting. If we return nonzero, we have
1231 * released the lock and the system call should return.
1233 static int wait_task_continued(struct wait_opts
*wo
, struct task_struct
*p
)
1239 if (!unlikely(wo
->wo_flags
& WCONTINUED
))
1242 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
))
1245 spin_lock_irq(&p
->sighand
->siglock
);
1246 /* Re-check with the lock held. */
1247 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
)) {
1248 spin_unlock_irq(&p
->sighand
->siglock
);
1251 if (!unlikely(wo
->wo_flags
& WNOWAIT
))
1252 p
->signal
->flags
&= ~SIGNAL_STOP_CONTINUED
;
1253 uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
1254 spin_unlock_irq(&p
->sighand
->siglock
);
1256 pid
= task_pid_vnr(p
);
1258 read_unlock(&tasklist_lock
);
1259 sched_annotate_sleep();
1262 retval
= wo
->wo_rusage
1263 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
1265 if (!retval
&& wo
->wo_stat
)
1266 retval
= put_user(0xffff, wo
->wo_stat
);
1270 retval
= wait_noreap_copyout(wo
, p
, pid
, uid
,
1271 CLD_CONTINUED
, SIGCONT
);
1272 BUG_ON(retval
== 0);
1279 * Consider @p for a wait by @parent.
1281 * -ECHILD should be in ->notask_error before the first call.
1282 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1283 * Returns zero if the search for a child should continue;
1284 * then ->notask_error is 0 if @p is an eligible child,
1285 * or another error from security_task_wait(), or still -ECHILD.
1287 static int wait_consider_task(struct wait_opts
*wo
, int ptrace
,
1288 struct task_struct
*p
)
1291 * We can race with wait_task_zombie() from another thread.
1292 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1293 * can't confuse the checks below.
1295 int exit_state
= ACCESS_ONCE(p
->exit_state
);
1298 if (unlikely(exit_state
== EXIT_DEAD
))
1301 ret
= eligible_child(wo
, p
);
1305 ret
= security_task_wait(p
);
1306 if (unlikely(ret
< 0)) {
1308 * If we have not yet seen any eligible child,
1309 * then let this error code replace -ECHILD.
1310 * A permission error will give the user a clue
1311 * to look for security policy problems, rather
1312 * than for mysterious wait bugs.
1314 if (wo
->notask_error
)
1315 wo
->notask_error
= ret
;
1319 if (unlikely(exit_state
== EXIT_TRACE
)) {
1321 * ptrace == 0 means we are the natural parent. In this case
1322 * we should clear notask_error, debugger will notify us.
1324 if (likely(!ptrace
))
1325 wo
->notask_error
= 0;
1329 if (likely(!ptrace
) && unlikely(p
->ptrace
)) {
1331 * If it is traced by its real parent's group, just pretend
1332 * the caller is ptrace_do_wait() and reap this child if it
1335 * This also hides group stop state from real parent; otherwise
1336 * a single stop can be reported twice as group and ptrace stop.
1337 * If a ptracer wants to distinguish these two events for its
1338 * own children it should create a separate process which takes
1339 * the role of real parent.
1341 if (!ptrace_reparented(p
))
1346 if (exit_state
== EXIT_ZOMBIE
) {
1347 /* we don't reap group leaders with subthreads */
1348 if (!delay_group_leader(p
)) {
1350 * A zombie ptracee is only visible to its ptracer.
1351 * Notification and reaping will be cascaded to the
1352 * real parent when the ptracer detaches.
1354 if (unlikely(ptrace
) || likely(!p
->ptrace
))
1355 return wait_task_zombie(wo
, p
);
1359 * Allow access to stopped/continued state via zombie by
1360 * falling through. Clearing of notask_error is complex.
1364 * If WEXITED is set, notask_error should naturally be
1365 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1366 * so, if there are live subthreads, there are events to
1367 * wait for. If all subthreads are dead, it's still safe
1368 * to clear - this function will be called again in finite
1369 * amount time once all the subthreads are released and
1370 * will then return without clearing.
1374 * Stopped state is per-task and thus can't change once the
1375 * target task dies. Only continued and exited can happen.
1376 * Clear notask_error if WCONTINUED | WEXITED.
1378 if (likely(!ptrace
) || (wo
->wo_flags
& (WCONTINUED
| WEXITED
)))
1379 wo
->notask_error
= 0;
1382 * @p is alive and it's gonna stop, continue or exit, so
1383 * there always is something to wait for.
1385 wo
->notask_error
= 0;
1389 * Wait for stopped. Depending on @ptrace, different stopped state
1390 * is used and the two don't interact with each other.
1392 ret
= wait_task_stopped(wo
, ptrace
, p
);
1397 * Wait for continued. There's only one continued state and the
1398 * ptracer can consume it which can confuse the real parent. Don't
1399 * use WCONTINUED from ptracer. You don't need or want it.
1401 return wait_task_continued(wo
, p
);
1405 * Do the work of do_wait() for one thread in the group, @tsk.
1407 * -ECHILD should be in ->notask_error before the first call.
1408 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1409 * Returns zero if the search for a child should continue; then
1410 * ->notask_error is 0 if there were any eligible children,
1411 * or another error from security_task_wait(), or still -ECHILD.
1413 static int do_wait_thread(struct wait_opts
*wo
, struct task_struct
*tsk
)
1415 struct task_struct
*p
;
1417 list_for_each_entry(p
, &tsk
->children
, sibling
) {
1418 int ret
= wait_consider_task(wo
, 0, p
);
1427 static int ptrace_do_wait(struct wait_opts
*wo
, struct task_struct
*tsk
)
1429 struct task_struct
*p
;
1431 list_for_each_entry(p
, &tsk
->ptraced
, ptrace_entry
) {
1432 int ret
= wait_consider_task(wo
, 1, p
);
1441 static int child_wait_callback(wait_queue_t
*wait
, unsigned mode
,
1442 int sync
, void *key
)
1444 struct wait_opts
*wo
= container_of(wait
, struct wait_opts
,
1446 struct task_struct
*p
= key
;
1448 if (!eligible_pid(wo
, p
))
1451 if ((wo
->wo_flags
& __WNOTHREAD
) && wait
->private != p
->parent
)
1454 return default_wake_function(wait
, mode
, sync
, key
);
1457 void __wake_up_parent(struct task_struct
*p
, struct task_struct
*parent
)
1459 __wake_up_sync_key(&parent
->signal
->wait_chldexit
,
1460 TASK_INTERRUPTIBLE
, 1, p
);
1463 static long do_wait(struct wait_opts
*wo
)
1465 struct task_struct
*tsk
;
1468 trace_sched_process_wait(wo
->wo_pid
);
1470 init_waitqueue_func_entry(&wo
->child_wait
, child_wait_callback
);
1471 wo
->child_wait
.private = current
;
1472 add_wait_queue(¤t
->signal
->wait_chldexit
, &wo
->child_wait
);
1475 * If there is nothing that can match our criteria, just get out.
1476 * We will clear ->notask_error to zero if we see any child that
1477 * might later match our criteria, even if we are not able to reap
1480 wo
->notask_error
= -ECHILD
;
1481 if ((wo
->wo_type
< PIDTYPE_MAX
) &&
1482 (!wo
->wo_pid
|| hlist_empty(&wo
->wo_pid
->tasks
[wo
->wo_type
])))
1485 set_current_state(TASK_INTERRUPTIBLE
);
1486 read_lock(&tasklist_lock
);
1489 retval
= do_wait_thread(wo
, tsk
);
1493 retval
= ptrace_do_wait(wo
, tsk
);
1497 if (wo
->wo_flags
& __WNOTHREAD
)
1499 } while_each_thread(current
, tsk
);
1500 read_unlock(&tasklist_lock
);
1503 retval
= wo
->notask_error
;
1504 if (!retval
&& !(wo
->wo_flags
& WNOHANG
)) {
1505 retval
= -ERESTARTSYS
;
1506 if (!signal_pending(current
)) {
1512 __set_current_state(TASK_RUNNING
);
1513 remove_wait_queue(¤t
->signal
->wait_chldexit
, &wo
->child_wait
);
1517 SYSCALL_DEFINE5(waitid
, int, which
, pid_t
, upid
, struct siginfo __user
*,
1518 infop
, int, options
, struct rusage __user
*, ru
)
1520 struct wait_opts wo
;
1521 struct pid
*pid
= NULL
;
1525 if (options
& ~(WNOHANG
|WNOWAIT
|WEXITED
|WSTOPPED
|WCONTINUED
))
1527 if (!(options
& (WEXITED
|WSTOPPED
|WCONTINUED
)))
1540 type
= PIDTYPE_PGID
;
1548 if (type
< PIDTYPE_MAX
)
1549 pid
= find_get_pid(upid
);
1553 wo
.wo_flags
= options
;
1563 * For a WNOHANG return, clear out all the fields
1564 * we would set so the user can easily tell the
1568 ret
= put_user(0, &infop
->si_signo
);
1570 ret
= put_user(0, &infop
->si_errno
);
1572 ret
= put_user(0, &infop
->si_code
);
1574 ret
= put_user(0, &infop
->si_pid
);
1576 ret
= put_user(0, &infop
->si_uid
);
1578 ret
= put_user(0, &infop
->si_status
);
1585 SYSCALL_DEFINE4(wait4
, pid_t
, upid
, int __user
*, stat_addr
,
1586 int, options
, struct rusage __user
*, ru
)
1588 struct wait_opts wo
;
1589 struct pid
*pid
= NULL
;
1593 if (options
& ~(WNOHANG
|WUNTRACED
|WCONTINUED
|
1594 __WNOTHREAD
|__WCLONE
|__WALL
))
1599 else if (upid
< 0) {
1600 type
= PIDTYPE_PGID
;
1601 pid
= find_get_pid(-upid
);
1602 } else if (upid
== 0) {
1603 type
= PIDTYPE_PGID
;
1604 pid
= get_task_pid(current
, PIDTYPE_PGID
);
1605 } else /* upid > 0 */ {
1607 pid
= find_get_pid(upid
);
1612 wo
.wo_flags
= options
| WEXITED
;
1614 wo
.wo_stat
= stat_addr
;
1622 #ifdef __ARCH_WANT_SYS_WAITPID
1625 * sys_waitpid() remains for compatibility. waitpid() should be
1626 * implemented by calling sys_wait4() from libc.a.
1628 SYSCALL_DEFINE3(waitpid
, pid_t
, pid
, int __user
*, stat_addr
, int, options
)
1630 return sys_wait4(pid
, stat_addr
, options
, NULL
);