1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992 Linus Torvalds
9 #include <linux/slab.h>
10 #include <linux/sched/autogroup.h>
11 #include <linux/sched/mm.h>
12 #include <linux/sched/stat.h>
13 #include <linux/sched/task.h>
14 #include <linux/sched/task_stack.h>
15 #include <linux/sched/cputime.h>
16 #include <linux/interrupt.h>
17 #include <linux/module.h>
18 #include <linux/capability.h>
19 #include <linux/completion.h>
20 #include <linux/personality.h>
21 #include <linux/tty.h>
22 #include <linux/iocontext.h>
23 #include <linux/key.h>
24 #include <linux/cpu.h>
25 #include <linux/acct.h>
26 #include <linux/tsacct_kern.h>
27 #include <linux/file.h>
28 #include <linux/fdtable.h>
29 #include <linux/freezer.h>
30 #include <linux/binfmts.h>
31 #include <linux/nsproxy.h>
32 #include <linux/pid_namespace.h>
33 #include <linux/ptrace.h>
34 #include <linux/profile.h>
35 #include <linux/mount.h>
36 #include <linux/proc_fs.h>
37 #include <linux/kthread.h>
38 #include <linux/mempolicy.h>
39 #include <linux/taskstats_kern.h>
40 #include <linux/delayacct.h>
41 #include <linux/cgroup.h>
42 #include <linux/syscalls.h>
43 #include <linux/signal.h>
44 #include <linux/posix-timers.h>
45 #include <linux/cn_proc.h>
46 #include <linux/mutex.h>
47 #include <linux/futex.h>
48 #include <linux/pipe_fs_i.h>
49 #include <linux/audit.h> /* for audit_free() */
50 #include <linux/resource.h>
51 #include <linux/blkdev.h>
52 #include <linux/task_io_accounting_ops.h>
53 #include <linux/tracehook.h>
54 #include <linux/fs_struct.h>
55 #include <linux/init_task.h>
56 #include <linux/perf_event.h>
57 #include <trace/events/sched.h>
58 #include <linux/hw_breakpoint.h>
59 #include <linux/oom.h>
60 #include <linux/writeback.h>
61 #include <linux/shm.h>
62 #include <linux/kcov.h>
63 #include <linux/random.h>
64 #include <linux/rcuwait.h>
65 #include <linux/compat.h>
67 #include <linux/uaccess.h>
68 #include <asm/unistd.h>
69 #include <asm/pgtable.h>
70 #include <asm/mmu_context.h>
72 static void __unhash_process(struct task_struct
*p
, bool group_dead
)
75 detach_pid(p
, PIDTYPE_PID
);
77 detach_pid(p
, PIDTYPE_TGID
);
78 detach_pid(p
, PIDTYPE_PGID
);
79 detach_pid(p
, PIDTYPE_SID
);
81 list_del_rcu(&p
->tasks
);
82 list_del_init(&p
->sibling
);
83 __this_cpu_dec(process_counts
);
85 list_del_rcu(&p
->thread_group
);
86 list_del_rcu(&p
->thread_node
);
90 * This function expects the tasklist_lock write-locked.
92 static void __exit_signal(struct task_struct
*tsk
)
94 struct signal_struct
*sig
= tsk
->signal
;
95 bool group_dead
= thread_group_leader(tsk
);
96 struct sighand_struct
*sighand
;
97 struct tty_struct
*uninitialized_var(tty
);
100 sighand
= rcu_dereference_check(tsk
->sighand
,
101 lockdep_tasklist_lock_is_held());
102 spin_lock(&sighand
->siglock
);
104 #ifdef CONFIG_POSIX_TIMERS
105 posix_cpu_timers_exit(tsk
);
107 posix_cpu_timers_exit_group(tsk
);
110 * This can only happen if the caller is de_thread().
111 * FIXME: this is the temporary hack, we should teach
112 * posix-cpu-timers to handle this case correctly.
114 if (unlikely(has_group_leader_pid(tsk
)))
115 posix_cpu_timers_exit_group(tsk
);
124 * If there is any task waiting for the group exit
127 if (sig
->notify_count
> 0 && !--sig
->notify_count
)
128 wake_up_process(sig
->group_exit_task
);
130 if (tsk
== sig
->curr_target
)
131 sig
->curr_target
= next_thread(tsk
);
134 add_device_randomness((const void*) &tsk
->se
.sum_exec_runtime
,
135 sizeof(unsigned long long));
138 * Accumulate here the counters for all threads as they die. We could
139 * skip the group leader because it is the last user of signal_struct,
140 * but we want to avoid the race with thread_group_cputime() which can
141 * see the empty ->thread_head list.
143 task_cputime(tsk
, &utime
, &stime
);
144 write_seqlock(&sig
->stats_lock
);
147 sig
->gtime
+= task_gtime(tsk
);
148 sig
->min_flt
+= tsk
->min_flt
;
149 sig
->maj_flt
+= tsk
->maj_flt
;
150 sig
->nvcsw
+= tsk
->nvcsw
;
151 sig
->nivcsw
+= tsk
->nivcsw
;
152 sig
->inblock
+= task_io_get_inblock(tsk
);
153 sig
->oublock
+= task_io_get_oublock(tsk
);
154 task_io_accounting_add(&sig
->ioac
, &tsk
->ioac
);
155 sig
->sum_sched_runtime
+= tsk
->se
.sum_exec_runtime
;
157 __unhash_process(tsk
, group_dead
);
158 write_sequnlock(&sig
->stats_lock
);
161 * Do this under ->siglock, we can race with another thread
162 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
164 flush_sigqueue(&tsk
->pending
);
166 spin_unlock(&sighand
->siglock
);
168 __cleanup_sighand(sighand
);
169 clear_tsk_thread_flag(tsk
, TIF_SIGPENDING
);
171 flush_sigqueue(&sig
->shared_pending
);
176 static void delayed_put_task_struct(struct rcu_head
*rhp
)
178 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
180 perf_event_delayed_put(tsk
);
181 trace_sched_process_free(tsk
);
182 put_task_struct(tsk
);
185 void put_task_struct_rcu_user(struct task_struct
*task
)
187 if (refcount_dec_and_test(&task
->rcu_users
))
188 call_rcu(&task
->rcu
, delayed_put_task_struct
);
191 void release_task(struct task_struct
*p
)
193 struct task_struct
*leader
;
196 /* don't need to get the RCU readlock here - the process is dead and
197 * can't be modifying its own credentials. But shut RCU-lockdep up */
199 atomic_dec(&__task_cred(p
)->user
->processes
);
205 write_lock_irq(&tasklist_lock
);
206 ptrace_release_task(p
);
210 * If we are the last non-leader member of the thread
211 * group, and the leader is zombie, then notify the
212 * group leader's parent process. (if it wants notification.)
215 leader
= p
->group_leader
;
216 if (leader
!= p
&& thread_group_empty(leader
)
217 && leader
->exit_state
== EXIT_ZOMBIE
) {
219 * If we were the last child thread and the leader has
220 * exited already, and the leader's parent ignores SIGCHLD,
221 * then we are the one who should release the leader.
223 zap_leader
= do_notify_parent(leader
, leader
->exit_signal
);
225 leader
->exit_state
= EXIT_DEAD
;
228 write_unlock_irq(&tasklist_lock
);
230 put_task_struct_rcu_user(p
);
233 if (unlikely(zap_leader
))
237 void rcuwait_wake_up(struct rcuwait
*w
)
239 struct task_struct
*task
;
244 * Order condition vs @task, such that everything prior to the load
245 * of @task is visible. This is the condition as to why the user called
246 * rcuwait_trywake() in the first place. Pairs with set_current_state()
247 * barrier (A) in rcuwait_wait_event().
250 * [S] tsk = current [S] cond = true
256 task
= rcu_dereference(w
->task
);
258 wake_up_process(task
);
263 * Determine if a process group is "orphaned", according to the POSIX
264 * definition in 2.2.2.52. Orphaned process groups are not to be affected
265 * by terminal-generated stop signals. Newly orphaned process groups are
266 * to receive a SIGHUP and a SIGCONT.
268 * "I ask you, have you ever known what it is to be an orphan?"
270 static int will_become_orphaned_pgrp(struct pid
*pgrp
,
271 struct task_struct
*ignored_task
)
273 struct task_struct
*p
;
275 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
276 if ((p
== ignored_task
) ||
277 (p
->exit_state
&& thread_group_empty(p
)) ||
278 is_global_init(p
->real_parent
))
281 if (task_pgrp(p
->real_parent
) != pgrp
&&
282 task_session(p
->real_parent
) == task_session(p
))
284 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
289 int is_current_pgrp_orphaned(void)
293 read_lock(&tasklist_lock
);
294 retval
= will_become_orphaned_pgrp(task_pgrp(current
), NULL
);
295 read_unlock(&tasklist_lock
);
300 static bool has_stopped_jobs(struct pid
*pgrp
)
302 struct task_struct
*p
;
304 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
305 if (p
->signal
->flags
& SIGNAL_STOP_STOPPED
)
307 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
313 * Check to see if any process groups have become orphaned as
314 * a result of our exiting, and if they have any stopped jobs,
315 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
318 kill_orphaned_pgrp(struct task_struct
*tsk
, struct task_struct
*parent
)
320 struct pid
*pgrp
= task_pgrp(tsk
);
321 struct task_struct
*ignored_task
= tsk
;
324 /* exit: our father is in a different pgrp than
325 * we are and we were the only connection outside.
327 parent
= tsk
->real_parent
;
329 /* reparent: our child is in a different pgrp than
330 * we are, and it was the only connection outside.
334 if (task_pgrp(parent
) != pgrp
&&
335 task_session(parent
) == task_session(tsk
) &&
336 will_become_orphaned_pgrp(pgrp
, ignored_task
) &&
337 has_stopped_jobs(pgrp
)) {
338 __kill_pgrp_info(SIGHUP
, SEND_SIG_PRIV
, pgrp
);
339 __kill_pgrp_info(SIGCONT
, SEND_SIG_PRIV
, pgrp
);
345 * A task is exiting. If it owned this mm, find a new owner for the mm.
347 void mm_update_next_owner(struct mm_struct
*mm
)
349 struct task_struct
*c
, *g
, *p
= current
;
353 * If the exiting or execing task is not the owner, it's
354 * someone else's problem.
359 * The current owner is exiting/execing and there are no other
360 * candidates. Do not leave the mm pointing to a possibly
361 * freed task structure.
363 if (atomic_read(&mm
->mm_users
) <= 1) {
364 WRITE_ONCE(mm
->owner
, NULL
);
368 read_lock(&tasklist_lock
);
370 * Search in the children
372 list_for_each_entry(c
, &p
->children
, sibling
) {
374 goto assign_new_owner
;
378 * Search in the siblings
380 list_for_each_entry(c
, &p
->real_parent
->children
, sibling
) {
382 goto assign_new_owner
;
386 * Search through everything else, we should not get here often.
388 for_each_process(g
) {
389 if (g
->flags
& PF_KTHREAD
)
391 for_each_thread(g
, c
) {
393 goto assign_new_owner
;
398 read_unlock(&tasklist_lock
);
400 * We found no owner yet mm_users > 1: this implies that we are
401 * most likely racing with swapoff (try_to_unuse()) or /proc or
402 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
404 WRITE_ONCE(mm
->owner
, NULL
);
411 * The task_lock protects c->mm from changing.
412 * We always want mm->owner->mm == mm
416 * Delay read_unlock() till we have the task_lock()
417 * to ensure that c does not slip away underneath us
419 read_unlock(&tasklist_lock
);
425 WRITE_ONCE(mm
->owner
, c
);
429 #endif /* CONFIG_MEMCG */
432 * Turn us into a lazy TLB process if we
435 static void exit_mm(void)
437 struct mm_struct
*mm
= current
->mm
;
438 struct core_state
*core_state
;
440 exit_mm_release(current
, mm
);
445 * Serialize with any possible pending coredump.
446 * We must hold mmap_sem around checking core_state
447 * and clearing tsk->mm. The core-inducing thread
448 * will increment ->nr_threads for each thread in the
449 * group with ->mm != NULL.
451 down_read(&mm
->mmap_sem
);
452 core_state
= mm
->core_state
;
454 struct core_thread self
;
456 up_read(&mm
->mmap_sem
);
459 if (self
.task
->flags
& PF_SIGNALED
)
460 self
.next
= xchg(&core_state
->dumper
.next
, &self
);
464 * Implies mb(), the result of xchg() must be visible
465 * to core_state->dumper.
467 if (atomic_dec_and_test(&core_state
->nr_threads
))
468 complete(&core_state
->startup
);
471 set_current_state(TASK_UNINTERRUPTIBLE
);
472 if (!self
.task
) /* see coredump_finish() */
474 freezable_schedule();
476 __set_current_state(TASK_RUNNING
);
477 down_read(&mm
->mmap_sem
);
480 BUG_ON(mm
!= current
->active_mm
);
481 /* more a memory barrier than a real lock */
484 up_read(&mm
->mmap_sem
);
485 enter_lazy_tlb(mm
, current
);
486 task_unlock(current
);
487 mm_update_next_owner(mm
);
489 if (test_thread_flag(TIF_MEMDIE
))
493 static struct task_struct
*find_alive_thread(struct task_struct
*p
)
495 struct task_struct
*t
;
497 for_each_thread(p
, t
) {
498 if (!(t
->flags
& PF_EXITING
))
504 static struct task_struct
*find_child_reaper(struct task_struct
*father
,
505 struct list_head
*dead
)
506 __releases(&tasklist_lock
)
507 __acquires(&tasklist_lock
)
509 struct pid_namespace
*pid_ns
= task_active_pid_ns(father
);
510 struct task_struct
*reaper
= pid_ns
->child_reaper
;
511 struct task_struct
*p
, *n
;
513 if (likely(reaper
!= father
))
516 reaper
= find_alive_thread(father
);
518 pid_ns
->child_reaper
= reaper
;
522 write_unlock_irq(&tasklist_lock
);
524 list_for_each_entry_safe(p
, n
, dead
, ptrace_entry
) {
525 list_del_init(&p
->ptrace_entry
);
529 zap_pid_ns_processes(pid_ns
);
530 write_lock_irq(&tasklist_lock
);
536 * When we die, we re-parent all our children, and try to:
537 * 1. give them to another thread in our thread group, if such a member exists
538 * 2. give it to the first ancestor process which prctl'd itself as a
539 * child_subreaper for its children (like a service manager)
540 * 3. give it to the init process (PID 1) in our pid namespace
542 static struct task_struct
*find_new_reaper(struct task_struct
*father
,
543 struct task_struct
*child_reaper
)
545 struct task_struct
*thread
, *reaper
;
547 thread
= find_alive_thread(father
);
551 if (father
->signal
->has_child_subreaper
) {
552 unsigned int ns_level
= task_pid(father
)->level
;
554 * Find the first ->is_child_subreaper ancestor in our pid_ns.
555 * We can't check reaper != child_reaper to ensure we do not
556 * cross the namespaces, the exiting parent could be injected
557 * by setns() + fork().
558 * We check pid->level, this is slightly more efficient than
559 * task_active_pid_ns(reaper) != task_active_pid_ns(father).
561 for (reaper
= father
->real_parent
;
562 task_pid(reaper
)->level
== ns_level
;
563 reaper
= reaper
->real_parent
) {
564 if (reaper
== &init_task
)
566 if (!reaper
->signal
->is_child_subreaper
)
568 thread
= find_alive_thread(reaper
);
578 * Any that need to be release_task'd are put on the @dead list.
580 static void reparent_leader(struct task_struct
*father
, struct task_struct
*p
,
581 struct list_head
*dead
)
583 if (unlikely(p
->exit_state
== EXIT_DEAD
))
586 /* We don't want people slaying init. */
587 p
->exit_signal
= SIGCHLD
;
589 /* If it has exited notify the new parent about this child's death. */
591 p
->exit_state
== EXIT_ZOMBIE
&& thread_group_empty(p
)) {
592 if (do_notify_parent(p
, p
->exit_signal
)) {
593 p
->exit_state
= EXIT_DEAD
;
594 list_add(&p
->ptrace_entry
, dead
);
598 kill_orphaned_pgrp(p
, father
);
602 * This does two things:
604 * A. Make init inherit all the child processes
605 * B. Check to see if any process groups have become orphaned
606 * as a result of our exiting, and if they have any stopped
607 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
609 static void forget_original_parent(struct task_struct
*father
,
610 struct list_head
*dead
)
612 struct task_struct
*p
, *t
, *reaper
;
614 if (unlikely(!list_empty(&father
->ptraced
)))
615 exit_ptrace(father
, dead
);
617 /* Can drop and reacquire tasklist_lock */
618 reaper
= find_child_reaper(father
, dead
);
619 if (list_empty(&father
->children
))
622 reaper
= find_new_reaper(father
, reaper
);
623 list_for_each_entry(p
, &father
->children
, sibling
) {
624 for_each_thread(p
, t
) {
625 t
->real_parent
= reaper
;
626 BUG_ON((!t
->ptrace
) != (t
->parent
== father
));
627 if (likely(!t
->ptrace
))
628 t
->parent
= t
->real_parent
;
629 if (t
->pdeath_signal
)
630 group_send_sig_info(t
->pdeath_signal
,
635 * If this is a threaded reparent there is no need to
636 * notify anyone anything has happened.
638 if (!same_thread_group(reaper
, father
))
639 reparent_leader(father
, p
, dead
);
641 list_splice_tail_init(&father
->children
, &reaper
->children
);
645 * Send signals to all our closest relatives so that they know
646 * to properly mourn us..
648 static void exit_notify(struct task_struct
*tsk
, int group_dead
)
651 struct task_struct
*p
, *n
;
654 write_lock_irq(&tasklist_lock
);
655 forget_original_parent(tsk
, &dead
);
658 kill_orphaned_pgrp(tsk
->group_leader
, NULL
);
660 tsk
->exit_state
= EXIT_ZOMBIE
;
661 if (unlikely(tsk
->ptrace
)) {
662 int sig
= thread_group_leader(tsk
) &&
663 thread_group_empty(tsk
) &&
664 !ptrace_reparented(tsk
) ?
665 tsk
->exit_signal
: SIGCHLD
;
666 autoreap
= do_notify_parent(tsk
, sig
);
667 } else if (thread_group_leader(tsk
)) {
668 autoreap
= thread_group_empty(tsk
) &&
669 do_notify_parent(tsk
, tsk
->exit_signal
);
675 tsk
->exit_state
= EXIT_DEAD
;
676 list_add(&tsk
->ptrace_entry
, &dead
);
679 /* mt-exec, de_thread() is waiting for group leader */
680 if (unlikely(tsk
->signal
->notify_count
< 0))
681 wake_up_process(tsk
->signal
->group_exit_task
);
682 write_unlock_irq(&tasklist_lock
);
684 list_for_each_entry_safe(p
, n
, &dead
, ptrace_entry
) {
685 list_del_init(&p
->ptrace_entry
);
690 #ifdef CONFIG_DEBUG_STACK_USAGE
691 static void check_stack_usage(void)
693 static DEFINE_SPINLOCK(low_water_lock
);
694 static int lowest_to_date
= THREAD_SIZE
;
697 free
= stack_not_used(current
);
699 if (free
>= lowest_to_date
)
702 spin_lock(&low_water_lock
);
703 if (free
< lowest_to_date
) {
704 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
705 current
->comm
, task_pid_nr(current
), free
);
706 lowest_to_date
= free
;
708 spin_unlock(&low_water_lock
);
711 static inline void check_stack_usage(void) {}
714 void __noreturn
do_exit(long code
)
716 struct task_struct
*tsk
= current
;
720 * We can get here from a kernel oops, sometimes with preemption off.
721 * Start by checking for critical errors.
722 * Then fix up important state like USER_DS and preemption.
723 * Then do everything else.
726 WARN_ON(blk_needs_flush_plug(tsk
));
728 if (unlikely(in_interrupt()))
729 panic("Aiee, killing interrupt handler!");
730 if (unlikely(!tsk
->pid
))
731 panic("Attempted to kill the idle task!");
734 * If do_exit is called because this processes oopsed, it's possible
735 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
736 * continuing. Amongst other possible reasons, this is to prevent
737 * mm_release()->clear_child_tid() from writing to a user-controlled
742 if (unlikely(in_atomic())) {
743 pr_info("note: %s[%d] exited with preempt_count %d\n",
744 current
->comm
, task_pid_nr(current
),
746 preempt_count_set(PREEMPT_ENABLED
);
749 profile_task_exit(tsk
);
752 ptrace_event(PTRACE_EVENT_EXIT
, code
);
754 validate_creds_for_do_exit(tsk
);
757 * We're taking recursive faults here in do_exit. Safest is to just
758 * leave this task alone and wait for reboot.
760 if (unlikely(tsk
->flags
& PF_EXITING
)) {
761 pr_alert("Fixing recursive fault but reboot is needed!\n");
762 futex_exit_recursive(tsk
);
763 set_current_state(TASK_UNINTERRUPTIBLE
);
767 exit_signals(tsk
); /* sets PF_EXITING */
769 /* sync mm's RSS info before statistics gathering */
771 sync_mm_rss(tsk
->mm
);
772 acct_update_integrals(tsk
);
773 group_dead
= atomic_dec_and_test(&tsk
->signal
->live
);
776 * If the last thread of global init has exited, panic
777 * immediately to get a useable coredump.
779 if (unlikely(is_global_init(tsk
)))
780 panic("Attempted to kill init! exitcode=0x%08x\n",
781 tsk
->signal
->group_exit_code
?: (int)code
);
783 #ifdef CONFIG_POSIX_TIMERS
784 hrtimer_cancel(&tsk
->signal
->real_timer
);
785 exit_itimers(tsk
->signal
);
788 setmax_mm_hiwater_rss(&tsk
->signal
->maxrss
, tsk
->mm
);
790 acct_collect(code
, group_dead
);
795 tsk
->exit_code
= code
;
796 taskstats_exit(tsk
, group_dead
);
802 trace_sched_process_exit(tsk
);
809 disassociate_ctty(1);
810 exit_task_namespaces(tsk
);
816 * Flush inherited counters to the parent - before the parent
817 * gets woken up by child-exit notifications.
819 * because of cgroup mode, must be called before cgroup_exit()
821 perf_event_exit_task(tsk
);
823 sched_autogroup_exit_task(tsk
);
827 * FIXME: do that only when needed, using sched_exit tracepoint
829 flush_ptrace_hw_breakpoint(tsk
);
831 exit_tasks_rcu_start();
832 exit_notify(tsk
, group_dead
);
833 proc_exit_connector(tsk
);
834 mpol_put_task_policy(tsk
);
836 if (unlikely(current
->pi_state_cache
))
837 kfree(current
->pi_state_cache
);
840 * Make sure we are holding no locks:
842 debug_check_no_locks_held();
845 exit_io_context(tsk
);
847 if (tsk
->splice_pipe
)
848 free_pipe_info(tsk
->splice_pipe
);
850 if (tsk
->task_frag
.page
)
851 put_page(tsk
->task_frag
.page
);
853 validate_creds_for_do_exit(tsk
);
858 __this_cpu_add(dirty_throttle_leaks
, tsk
->nr_dirtied
);
860 exit_tasks_rcu_finish();
862 lockdep_free_task(tsk
);
865 EXPORT_SYMBOL_GPL(do_exit
);
867 void complete_and_exit(struct completion
*comp
, long code
)
874 EXPORT_SYMBOL(complete_and_exit
);
876 SYSCALL_DEFINE1(exit
, int, error_code
)
878 do_exit((error_code
&0xff)<<8);
882 * Take down every thread in the group. This is called by fatal signals
883 * as well as by sys_exit_group (below).
886 do_group_exit(int exit_code
)
888 struct signal_struct
*sig
= current
->signal
;
890 BUG_ON(exit_code
& 0x80); /* core dumps don't get here */
892 if (signal_group_exit(sig
))
893 exit_code
= sig
->group_exit_code
;
894 else if (!thread_group_empty(current
)) {
895 struct sighand_struct
*const sighand
= current
->sighand
;
897 spin_lock_irq(&sighand
->siglock
);
898 if (signal_group_exit(sig
))
899 /* Another thread got here before we took the lock. */
900 exit_code
= sig
->group_exit_code
;
902 sig
->group_exit_code
= exit_code
;
903 sig
->flags
= SIGNAL_GROUP_EXIT
;
904 zap_other_threads(current
);
906 spin_unlock_irq(&sighand
->siglock
);
914 * this kills every thread in the thread group. Note that any externally
915 * wait4()-ing process will get the correct exit code - even if this
916 * thread is not the thread group leader.
918 SYSCALL_DEFINE1(exit_group
, int, error_code
)
920 do_group_exit((error_code
& 0xff) << 8);
933 enum pid_type wo_type
;
937 struct waitid_info
*wo_info
;
939 struct rusage
*wo_rusage
;
941 wait_queue_entry_t child_wait
;
945 static int eligible_pid(struct wait_opts
*wo
, struct task_struct
*p
)
947 return wo
->wo_type
== PIDTYPE_MAX
||
948 task_pid_type(p
, wo
->wo_type
) == wo
->wo_pid
;
952 eligible_child(struct wait_opts
*wo
, bool ptrace
, struct task_struct
*p
)
954 if (!eligible_pid(wo
, p
))
958 * Wait for all children (clone and not) if __WALL is set or
959 * if it is traced by us.
961 if (ptrace
|| (wo
->wo_flags
& __WALL
))
965 * Otherwise, wait for clone children *only* if __WCLONE is set;
966 * otherwise, wait for non-clone children *only*.
968 * Note: a "clone" child here is one that reports to its parent
969 * using a signal other than SIGCHLD, or a non-leader thread which
970 * we can only see if it is traced by us.
972 if ((p
->exit_signal
!= SIGCHLD
) ^ !!(wo
->wo_flags
& __WCLONE
))
979 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
980 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
981 * the lock and this task is uninteresting. If we return nonzero, we have
982 * released the lock and the system call should return.
984 static int wait_task_zombie(struct wait_opts
*wo
, struct task_struct
*p
)
987 pid_t pid
= task_pid_vnr(p
);
988 uid_t uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
989 struct waitid_info
*infop
;
991 if (!likely(wo
->wo_flags
& WEXITED
))
994 if (unlikely(wo
->wo_flags
& WNOWAIT
)) {
995 status
= p
->exit_code
;
997 read_unlock(&tasklist_lock
);
998 sched_annotate_sleep();
1000 getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
);
1005 * Move the task's state to DEAD/TRACE, only one thread can do this.
1007 state
= (ptrace_reparented(p
) && thread_group_leader(p
)) ?
1008 EXIT_TRACE
: EXIT_DEAD
;
1009 if (cmpxchg(&p
->exit_state
, EXIT_ZOMBIE
, state
) != EXIT_ZOMBIE
)
1012 * We own this thread, nobody else can reap it.
1014 read_unlock(&tasklist_lock
);
1015 sched_annotate_sleep();
1018 * Check thread_group_leader() to exclude the traced sub-threads.
1020 if (state
== EXIT_DEAD
&& thread_group_leader(p
)) {
1021 struct signal_struct
*sig
= p
->signal
;
1022 struct signal_struct
*psig
= current
->signal
;
1023 unsigned long maxrss
;
1024 u64 tgutime
, tgstime
;
1027 * The resource counters for the group leader are in its
1028 * own task_struct. Those for dead threads in the group
1029 * are in its signal_struct, as are those for the child
1030 * processes it has previously reaped. All these
1031 * accumulate in the parent's signal_struct c* fields.
1033 * We don't bother to take a lock here to protect these
1034 * p->signal fields because the whole thread group is dead
1035 * and nobody can change them.
1037 * psig->stats_lock also protects us from our sub-theads
1038 * which can reap other children at the same time. Until
1039 * we change k_getrusage()-like users to rely on this lock
1040 * we have to take ->siglock as well.
1042 * We use thread_group_cputime_adjusted() to get times for
1043 * the thread group, which consolidates times for all threads
1044 * in the group including the group leader.
1046 thread_group_cputime_adjusted(p
, &tgutime
, &tgstime
);
1047 spin_lock_irq(¤t
->sighand
->siglock
);
1048 write_seqlock(&psig
->stats_lock
);
1049 psig
->cutime
+= tgutime
+ sig
->cutime
;
1050 psig
->cstime
+= tgstime
+ sig
->cstime
;
1051 psig
->cgtime
+= task_gtime(p
) + sig
->gtime
+ sig
->cgtime
;
1053 p
->min_flt
+ sig
->min_flt
+ sig
->cmin_flt
;
1055 p
->maj_flt
+ sig
->maj_flt
+ sig
->cmaj_flt
;
1057 p
->nvcsw
+ sig
->nvcsw
+ sig
->cnvcsw
;
1059 p
->nivcsw
+ sig
->nivcsw
+ sig
->cnivcsw
;
1061 task_io_get_inblock(p
) +
1062 sig
->inblock
+ sig
->cinblock
;
1064 task_io_get_oublock(p
) +
1065 sig
->oublock
+ sig
->coublock
;
1066 maxrss
= max(sig
->maxrss
, sig
->cmaxrss
);
1067 if (psig
->cmaxrss
< maxrss
)
1068 psig
->cmaxrss
= maxrss
;
1069 task_io_accounting_add(&psig
->ioac
, &p
->ioac
);
1070 task_io_accounting_add(&psig
->ioac
, &sig
->ioac
);
1071 write_sequnlock(&psig
->stats_lock
);
1072 spin_unlock_irq(¤t
->sighand
->siglock
);
1076 getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
);
1077 status
= (p
->signal
->flags
& SIGNAL_GROUP_EXIT
)
1078 ? p
->signal
->group_exit_code
: p
->exit_code
;
1079 wo
->wo_stat
= status
;
1081 if (state
== EXIT_TRACE
) {
1082 write_lock_irq(&tasklist_lock
);
1083 /* We dropped tasklist, ptracer could die and untrace */
1086 /* If parent wants a zombie, don't release it now */
1087 state
= EXIT_ZOMBIE
;
1088 if (do_notify_parent(p
, p
->exit_signal
))
1090 p
->exit_state
= state
;
1091 write_unlock_irq(&tasklist_lock
);
1093 if (state
== EXIT_DEAD
)
1097 infop
= wo
->wo_info
;
1099 if ((status
& 0x7f) == 0) {
1100 infop
->cause
= CLD_EXITED
;
1101 infop
->status
= status
>> 8;
1103 infop
->cause
= (status
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
1104 infop
->status
= status
& 0x7f;
1113 static int *task_stopped_code(struct task_struct
*p
, bool ptrace
)
1116 if (task_is_traced(p
) && !(p
->jobctl
& JOBCTL_LISTENING
))
1117 return &p
->exit_code
;
1119 if (p
->signal
->flags
& SIGNAL_STOP_STOPPED
)
1120 return &p
->signal
->group_exit_code
;
1126 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1128 * @ptrace: is the wait for ptrace
1129 * @p: task to wait for
1131 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1134 * read_lock(&tasklist_lock), which is released if return value is
1135 * non-zero. Also, grabs and releases @p->sighand->siglock.
1138 * 0 if wait condition didn't exist and search for other wait conditions
1139 * should continue. Non-zero return, -errno on failure and @p's pid on
1140 * success, implies that tasklist_lock is released and wait condition
1141 * search should terminate.
1143 static int wait_task_stopped(struct wait_opts
*wo
,
1144 int ptrace
, struct task_struct
*p
)
1146 struct waitid_info
*infop
;
1147 int exit_code
, *p_code
, why
;
1148 uid_t uid
= 0; /* unneeded, required by compiler */
1152 * Traditionally we see ptrace'd stopped tasks regardless of options.
1154 if (!ptrace
&& !(wo
->wo_flags
& WUNTRACED
))
1157 if (!task_stopped_code(p
, ptrace
))
1161 spin_lock_irq(&p
->sighand
->siglock
);
1163 p_code
= task_stopped_code(p
, ptrace
);
1164 if (unlikely(!p_code
))
1167 exit_code
= *p_code
;
1171 if (!unlikely(wo
->wo_flags
& WNOWAIT
))
1174 uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
1176 spin_unlock_irq(&p
->sighand
->siglock
);
1181 * Now we are pretty sure this task is interesting.
1182 * Make sure it doesn't get reaped out from under us while we
1183 * give up the lock and then examine it below. We don't want to
1184 * keep holding onto the tasklist_lock while we call getrusage and
1185 * possibly take page faults for user memory.
1188 pid
= task_pid_vnr(p
);
1189 why
= ptrace
? CLD_TRAPPED
: CLD_STOPPED
;
1190 read_unlock(&tasklist_lock
);
1191 sched_annotate_sleep();
1193 getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
);
1196 if (likely(!(wo
->wo_flags
& WNOWAIT
)))
1197 wo
->wo_stat
= (exit_code
<< 8) | 0x7f;
1199 infop
= wo
->wo_info
;
1202 infop
->status
= exit_code
;
1210 * Handle do_wait work for one task in a live, non-stopped state.
1211 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1212 * the lock and this task is uninteresting. If we return nonzero, we have
1213 * released the lock and the system call should return.
1215 static int wait_task_continued(struct wait_opts
*wo
, struct task_struct
*p
)
1217 struct waitid_info
*infop
;
1221 if (!unlikely(wo
->wo_flags
& WCONTINUED
))
1224 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
))
1227 spin_lock_irq(&p
->sighand
->siglock
);
1228 /* Re-check with the lock held. */
1229 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
)) {
1230 spin_unlock_irq(&p
->sighand
->siglock
);
1233 if (!unlikely(wo
->wo_flags
& WNOWAIT
))
1234 p
->signal
->flags
&= ~SIGNAL_STOP_CONTINUED
;
1235 uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
1236 spin_unlock_irq(&p
->sighand
->siglock
);
1238 pid
= task_pid_vnr(p
);
1240 read_unlock(&tasklist_lock
);
1241 sched_annotate_sleep();
1243 getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
);
1246 infop
= wo
->wo_info
;
1248 wo
->wo_stat
= 0xffff;
1250 infop
->cause
= CLD_CONTINUED
;
1253 infop
->status
= SIGCONT
;
1259 * Consider @p for a wait by @parent.
1261 * -ECHILD should be in ->notask_error before the first call.
1262 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1263 * Returns zero if the search for a child should continue;
1264 * then ->notask_error is 0 if @p is an eligible child,
1267 static int wait_consider_task(struct wait_opts
*wo
, int ptrace
,
1268 struct task_struct
*p
)
1271 * We can race with wait_task_zombie() from another thread.
1272 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1273 * can't confuse the checks below.
1275 int exit_state
= READ_ONCE(p
->exit_state
);
1278 if (unlikely(exit_state
== EXIT_DEAD
))
1281 ret
= eligible_child(wo
, ptrace
, p
);
1285 if (unlikely(exit_state
== EXIT_TRACE
)) {
1287 * ptrace == 0 means we are the natural parent. In this case
1288 * we should clear notask_error, debugger will notify us.
1290 if (likely(!ptrace
))
1291 wo
->notask_error
= 0;
1295 if (likely(!ptrace
) && unlikely(p
->ptrace
)) {
1297 * If it is traced by its real parent's group, just pretend
1298 * the caller is ptrace_do_wait() and reap this child if it
1301 * This also hides group stop state from real parent; otherwise
1302 * a single stop can be reported twice as group and ptrace stop.
1303 * If a ptracer wants to distinguish these two events for its
1304 * own children it should create a separate process which takes
1305 * the role of real parent.
1307 if (!ptrace_reparented(p
))
1312 if (exit_state
== EXIT_ZOMBIE
) {
1313 /* we don't reap group leaders with subthreads */
1314 if (!delay_group_leader(p
)) {
1316 * A zombie ptracee is only visible to its ptracer.
1317 * Notification and reaping will be cascaded to the
1318 * real parent when the ptracer detaches.
1320 if (unlikely(ptrace
) || likely(!p
->ptrace
))
1321 return wait_task_zombie(wo
, p
);
1325 * Allow access to stopped/continued state via zombie by
1326 * falling through. Clearing of notask_error is complex.
1330 * If WEXITED is set, notask_error should naturally be
1331 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1332 * so, if there are live subthreads, there are events to
1333 * wait for. If all subthreads are dead, it's still safe
1334 * to clear - this function will be called again in finite
1335 * amount time once all the subthreads are released and
1336 * will then return without clearing.
1340 * Stopped state is per-task and thus can't change once the
1341 * target task dies. Only continued and exited can happen.
1342 * Clear notask_error if WCONTINUED | WEXITED.
1344 if (likely(!ptrace
) || (wo
->wo_flags
& (WCONTINUED
| WEXITED
)))
1345 wo
->notask_error
= 0;
1348 * @p is alive and it's gonna stop, continue or exit, so
1349 * there always is something to wait for.
1351 wo
->notask_error
= 0;
1355 * Wait for stopped. Depending on @ptrace, different stopped state
1356 * is used and the two don't interact with each other.
1358 ret
= wait_task_stopped(wo
, ptrace
, p
);
1363 * Wait for continued. There's only one continued state and the
1364 * ptracer can consume it which can confuse the real parent. Don't
1365 * use WCONTINUED from ptracer. You don't need or want it.
1367 return wait_task_continued(wo
, p
);
1371 * Do the work of do_wait() for one thread in the group, @tsk.
1373 * -ECHILD should be in ->notask_error before the first call.
1374 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1375 * Returns zero if the search for a child should continue; then
1376 * ->notask_error is 0 if there were any eligible children,
1379 static int do_wait_thread(struct wait_opts
*wo
, struct task_struct
*tsk
)
1381 struct task_struct
*p
;
1383 list_for_each_entry(p
, &tsk
->children
, sibling
) {
1384 int ret
= wait_consider_task(wo
, 0, p
);
1393 static int ptrace_do_wait(struct wait_opts
*wo
, struct task_struct
*tsk
)
1395 struct task_struct
*p
;
1397 list_for_each_entry(p
, &tsk
->ptraced
, ptrace_entry
) {
1398 int ret
= wait_consider_task(wo
, 1, p
);
1407 static int child_wait_callback(wait_queue_entry_t
*wait
, unsigned mode
,
1408 int sync
, void *key
)
1410 struct wait_opts
*wo
= container_of(wait
, struct wait_opts
,
1412 struct task_struct
*p
= key
;
1414 if (!eligible_pid(wo
, p
))
1417 if ((wo
->wo_flags
& __WNOTHREAD
) && wait
->private != p
->parent
)
1420 return default_wake_function(wait
, mode
, sync
, key
);
1423 void __wake_up_parent(struct task_struct
*p
, struct task_struct
*parent
)
1425 __wake_up_sync_key(&parent
->signal
->wait_chldexit
,
1426 TASK_INTERRUPTIBLE
, 1, p
);
1429 static long do_wait(struct wait_opts
*wo
)
1431 struct task_struct
*tsk
;
1434 trace_sched_process_wait(wo
->wo_pid
);
1436 init_waitqueue_func_entry(&wo
->child_wait
, child_wait_callback
);
1437 wo
->child_wait
.private = current
;
1438 add_wait_queue(¤t
->signal
->wait_chldexit
, &wo
->child_wait
);
1441 * If there is nothing that can match our criteria, just get out.
1442 * We will clear ->notask_error to zero if we see any child that
1443 * might later match our criteria, even if we are not able to reap
1446 wo
->notask_error
= -ECHILD
;
1447 if ((wo
->wo_type
< PIDTYPE_MAX
) &&
1448 (!wo
->wo_pid
|| hlist_empty(&wo
->wo_pid
->tasks
[wo
->wo_type
])))
1451 set_current_state(TASK_INTERRUPTIBLE
);
1452 read_lock(&tasklist_lock
);
1455 retval
= do_wait_thread(wo
, tsk
);
1459 retval
= ptrace_do_wait(wo
, tsk
);
1463 if (wo
->wo_flags
& __WNOTHREAD
)
1465 } while_each_thread(current
, tsk
);
1466 read_unlock(&tasklist_lock
);
1469 retval
= wo
->notask_error
;
1470 if (!retval
&& !(wo
->wo_flags
& WNOHANG
)) {
1471 retval
= -ERESTARTSYS
;
1472 if (!signal_pending(current
)) {
1478 __set_current_state(TASK_RUNNING
);
1479 remove_wait_queue(¤t
->signal
->wait_chldexit
, &wo
->child_wait
);
1483 static struct pid
*pidfd_get_pid(unsigned int fd
)
1490 return ERR_PTR(-EBADF
);
1492 pid
= pidfd_pid(f
.file
);
1500 static long kernel_waitid(int which
, pid_t upid
, struct waitid_info
*infop
,
1501 int options
, struct rusage
*ru
)
1503 struct wait_opts wo
;
1504 struct pid
*pid
= NULL
;
1508 if (options
& ~(WNOHANG
|WNOWAIT
|WEXITED
|WSTOPPED
|WCONTINUED
|
1509 __WNOTHREAD
|__WCLONE
|__WALL
))
1511 if (!(options
& (WEXITED
|WSTOPPED
|WCONTINUED
)))
1523 pid
= find_get_pid(upid
);
1526 type
= PIDTYPE_PGID
;
1531 pid
= find_get_pid(upid
);
1533 pid
= get_task_pid(current
, PIDTYPE_PGID
);
1540 pid
= pidfd_get_pid(upid
);
1542 return PTR_ERR(pid
);
1550 wo
.wo_flags
= options
;
1559 SYSCALL_DEFINE5(waitid
, int, which
, pid_t
, upid
, struct siginfo __user
*,
1560 infop
, int, options
, struct rusage __user
*, ru
)
1563 struct waitid_info info
= {.status
= 0};
1564 long err
= kernel_waitid(which
, upid
, &info
, options
, ru
? &r
: NULL
);
1570 if (ru
&& copy_to_user(ru
, &r
, sizeof(struct rusage
)))
1576 if (!user_access_begin(infop
, sizeof(*infop
)))
1579 unsafe_put_user(signo
, &infop
->si_signo
, Efault
);
1580 unsafe_put_user(0, &infop
->si_errno
, Efault
);
1581 unsafe_put_user(info
.cause
, &infop
->si_code
, Efault
);
1582 unsafe_put_user(info
.pid
, &infop
->si_pid
, Efault
);
1583 unsafe_put_user(info
.uid
, &infop
->si_uid
, Efault
);
1584 unsafe_put_user(info
.status
, &infop
->si_status
, Efault
);
1592 long kernel_wait4(pid_t upid
, int __user
*stat_addr
, int options
,
1595 struct wait_opts wo
;
1596 struct pid
*pid
= NULL
;
1600 if (options
& ~(WNOHANG
|WUNTRACED
|WCONTINUED
|
1601 __WNOTHREAD
|__WCLONE
|__WALL
))
1604 /* -INT_MIN is not defined */
1605 if (upid
== INT_MIN
)
1610 else if (upid
< 0) {
1611 type
= PIDTYPE_PGID
;
1612 pid
= find_get_pid(-upid
);
1613 } else if (upid
== 0) {
1614 type
= PIDTYPE_PGID
;
1615 pid
= get_task_pid(current
, PIDTYPE_PGID
);
1616 } else /* upid > 0 */ {
1618 pid
= find_get_pid(upid
);
1623 wo
.wo_flags
= options
| WEXITED
;
1629 if (ret
> 0 && stat_addr
&& put_user(wo
.wo_stat
, stat_addr
))
1635 SYSCALL_DEFINE4(wait4
, pid_t
, upid
, int __user
*, stat_addr
,
1636 int, options
, struct rusage __user
*, ru
)
1639 long err
= kernel_wait4(upid
, stat_addr
, options
, ru
? &r
: NULL
);
1642 if (ru
&& copy_to_user(ru
, &r
, sizeof(struct rusage
)))
1648 #ifdef __ARCH_WANT_SYS_WAITPID
1651 * sys_waitpid() remains for compatibility. waitpid() should be
1652 * implemented by calling sys_wait4() from libc.a.
1654 SYSCALL_DEFINE3(waitpid
, pid_t
, pid
, int __user
*, stat_addr
, int, options
)
1656 return kernel_wait4(pid
, stat_addr
, options
, NULL
);
1661 #ifdef CONFIG_COMPAT
1662 COMPAT_SYSCALL_DEFINE4(wait4
,
1664 compat_uint_t __user
*, stat_addr
,
1666 struct compat_rusage __user
*, ru
)
1669 long err
= kernel_wait4(pid
, stat_addr
, options
, ru
? &r
: NULL
);
1671 if (ru
&& put_compat_rusage(&r
, ru
))
1677 COMPAT_SYSCALL_DEFINE5(waitid
,
1678 int, which
, compat_pid_t
, pid
,
1679 struct compat_siginfo __user
*, infop
, int, options
,
1680 struct compat_rusage __user
*, uru
)
1683 struct waitid_info info
= {.status
= 0};
1684 long err
= kernel_waitid(which
, pid
, &info
, options
, uru
? &ru
: NULL
);
1690 /* kernel_waitid() overwrites everything in ru */
1691 if (COMPAT_USE_64BIT_TIME
)
1692 err
= copy_to_user(uru
, &ru
, sizeof(ru
));
1694 err
= put_compat_rusage(&ru
, uru
);
1703 if (!user_access_begin(infop
, sizeof(*infop
)))
1706 unsafe_put_user(signo
, &infop
->si_signo
, Efault
);
1707 unsafe_put_user(0, &infop
->si_errno
, Efault
);
1708 unsafe_put_user(info
.cause
, &infop
->si_code
, Efault
);
1709 unsafe_put_user(info
.pid
, &infop
->si_pid
, Efault
);
1710 unsafe_put_user(info
.uid
, &infop
->si_uid
, Efault
);
1711 unsafe_put_user(info
.status
, &infop
->si_status
, Efault
);
1720 __weak
void abort(void)
1724 /* if that doesn't kill us, halt */
1725 panic("Oops failed to kill thread");
1727 EXPORT_SYMBOL(abort
);