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
);
115 * If there is any task waiting for the group exit
118 if (sig
->notify_count
> 0 && !--sig
->notify_count
)
119 wake_up_process(sig
->group_exit_task
);
121 if (tsk
== sig
->curr_target
)
122 sig
->curr_target
= next_thread(tsk
);
125 add_device_randomness((const void*) &tsk
->se
.sum_exec_runtime
,
126 sizeof(unsigned long long));
129 * Accumulate here the counters for all threads as they die. We could
130 * skip the group leader because it is the last user of signal_struct,
131 * but we want to avoid the race with thread_group_cputime() which can
132 * see the empty ->thread_head list.
134 task_cputime(tsk
, &utime
, &stime
);
135 write_seqlock(&sig
->stats_lock
);
138 sig
->gtime
+= task_gtime(tsk
);
139 sig
->min_flt
+= tsk
->min_flt
;
140 sig
->maj_flt
+= tsk
->maj_flt
;
141 sig
->nvcsw
+= tsk
->nvcsw
;
142 sig
->nivcsw
+= tsk
->nivcsw
;
143 sig
->inblock
+= task_io_get_inblock(tsk
);
144 sig
->oublock
+= task_io_get_oublock(tsk
);
145 task_io_accounting_add(&sig
->ioac
, &tsk
->ioac
);
146 sig
->sum_sched_runtime
+= tsk
->se
.sum_exec_runtime
;
148 __unhash_process(tsk
, group_dead
);
149 write_sequnlock(&sig
->stats_lock
);
152 * Do this under ->siglock, we can race with another thread
153 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
155 flush_sigqueue(&tsk
->pending
);
157 spin_unlock(&sighand
->siglock
);
159 __cleanup_sighand(sighand
);
160 clear_tsk_thread_flag(tsk
, TIF_SIGPENDING
);
162 flush_sigqueue(&sig
->shared_pending
);
167 static void delayed_put_task_struct(struct rcu_head
*rhp
)
169 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
171 perf_event_delayed_put(tsk
);
172 trace_sched_process_free(tsk
);
173 put_task_struct(tsk
);
176 void put_task_struct_rcu_user(struct task_struct
*task
)
178 if (refcount_dec_and_test(&task
->rcu_users
))
179 call_rcu(&task
->rcu
, delayed_put_task_struct
);
182 void release_task(struct task_struct
*p
)
184 struct task_struct
*leader
;
185 struct pid
*thread_pid
;
188 /* don't need to get the RCU readlock here - the process is dead and
189 * can't be modifying its own credentials. But shut RCU-lockdep up */
191 atomic_dec(&__task_cred(p
)->user
->processes
);
196 write_lock_irq(&tasklist_lock
);
197 ptrace_release_task(p
);
198 thread_pid
= get_pid(p
->thread_pid
);
202 * If we are the last non-leader member of the thread
203 * group, and the leader is zombie, then notify the
204 * group leader's parent process. (if it wants notification.)
207 leader
= p
->group_leader
;
208 if (leader
!= p
&& thread_group_empty(leader
)
209 && leader
->exit_state
== EXIT_ZOMBIE
) {
211 * If we were the last child thread and the leader has
212 * exited already, and the leader's parent ignores SIGCHLD,
213 * then we are the one who should release the leader.
215 zap_leader
= do_notify_parent(leader
, leader
->exit_signal
);
217 leader
->exit_state
= EXIT_DEAD
;
220 write_unlock_irq(&tasklist_lock
);
221 proc_flush_pid(thread_pid
);
224 put_task_struct_rcu_user(p
);
227 if (unlikely(zap_leader
))
231 void rcuwait_wake_up(struct rcuwait
*w
)
233 struct task_struct
*task
;
238 * Order condition vs @task, such that everything prior to the load
239 * of @task is visible. This is the condition as to why the user called
240 * rcuwait_trywake() in the first place. Pairs with set_current_state()
241 * barrier (A) in rcuwait_wait_event().
244 * [S] tsk = current [S] cond = true
250 task
= rcu_dereference(w
->task
);
252 wake_up_process(task
);
255 EXPORT_SYMBOL_GPL(rcuwait_wake_up
);
258 * Determine if a process group is "orphaned", according to the POSIX
259 * definition in 2.2.2.52. Orphaned process groups are not to be affected
260 * by terminal-generated stop signals. Newly orphaned process groups are
261 * to receive a SIGHUP and a SIGCONT.
263 * "I ask you, have you ever known what it is to be an orphan?"
265 static int will_become_orphaned_pgrp(struct pid
*pgrp
,
266 struct task_struct
*ignored_task
)
268 struct task_struct
*p
;
270 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
271 if ((p
== ignored_task
) ||
272 (p
->exit_state
&& thread_group_empty(p
)) ||
273 is_global_init(p
->real_parent
))
276 if (task_pgrp(p
->real_parent
) != pgrp
&&
277 task_session(p
->real_parent
) == task_session(p
))
279 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
284 int is_current_pgrp_orphaned(void)
288 read_lock(&tasklist_lock
);
289 retval
= will_become_orphaned_pgrp(task_pgrp(current
), NULL
);
290 read_unlock(&tasklist_lock
);
295 static bool has_stopped_jobs(struct pid
*pgrp
)
297 struct task_struct
*p
;
299 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
300 if (p
->signal
->flags
& SIGNAL_STOP_STOPPED
)
302 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
308 * Check to see if any process groups have become orphaned as
309 * a result of our exiting, and if they have any stopped jobs,
310 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
313 kill_orphaned_pgrp(struct task_struct
*tsk
, struct task_struct
*parent
)
315 struct pid
*pgrp
= task_pgrp(tsk
);
316 struct task_struct
*ignored_task
= tsk
;
319 /* exit: our father is in a different pgrp than
320 * we are and we were the only connection outside.
322 parent
= tsk
->real_parent
;
324 /* reparent: our child is in a different pgrp than
325 * we are, and it was the only connection outside.
329 if (task_pgrp(parent
) != pgrp
&&
330 task_session(parent
) == task_session(tsk
) &&
331 will_become_orphaned_pgrp(pgrp
, ignored_task
) &&
332 has_stopped_jobs(pgrp
)) {
333 __kill_pgrp_info(SIGHUP
, SEND_SIG_PRIV
, pgrp
);
334 __kill_pgrp_info(SIGCONT
, SEND_SIG_PRIV
, pgrp
);
340 * A task is exiting. If it owned this mm, find a new owner for the mm.
342 void mm_update_next_owner(struct mm_struct
*mm
)
344 struct task_struct
*c
, *g
, *p
= current
;
348 * If the exiting or execing task is not the owner, it's
349 * someone else's problem.
354 * The current owner is exiting/execing and there are no other
355 * candidates. Do not leave the mm pointing to a possibly
356 * freed task structure.
358 if (atomic_read(&mm
->mm_users
) <= 1) {
359 WRITE_ONCE(mm
->owner
, NULL
);
363 read_lock(&tasklist_lock
);
365 * Search in the children
367 list_for_each_entry(c
, &p
->children
, sibling
) {
369 goto assign_new_owner
;
373 * Search in the siblings
375 list_for_each_entry(c
, &p
->real_parent
->children
, sibling
) {
377 goto assign_new_owner
;
381 * Search through everything else, we should not get here often.
383 for_each_process(g
) {
384 if (g
->flags
& PF_KTHREAD
)
386 for_each_thread(g
, c
) {
388 goto assign_new_owner
;
393 read_unlock(&tasklist_lock
);
395 * We found no owner yet mm_users > 1: this implies that we are
396 * most likely racing with swapoff (try_to_unuse()) or /proc or
397 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
399 WRITE_ONCE(mm
->owner
, NULL
);
406 * The task_lock protects c->mm from changing.
407 * We always want mm->owner->mm == mm
411 * Delay read_unlock() till we have the task_lock()
412 * to ensure that c does not slip away underneath us
414 read_unlock(&tasklist_lock
);
420 WRITE_ONCE(mm
->owner
, c
);
424 #endif /* CONFIG_MEMCG */
427 * Turn us into a lazy TLB process if we
430 static void exit_mm(void)
432 struct mm_struct
*mm
= current
->mm
;
433 struct core_state
*core_state
;
435 exit_mm_release(current
, mm
);
440 * Serialize with any possible pending coredump.
441 * We must hold mmap_sem around checking core_state
442 * and clearing tsk->mm. The core-inducing thread
443 * will increment ->nr_threads for each thread in the
444 * group with ->mm != NULL.
446 down_read(&mm
->mmap_sem
);
447 core_state
= mm
->core_state
;
449 struct core_thread self
;
451 up_read(&mm
->mmap_sem
);
454 self
.next
= xchg(&core_state
->dumper
.next
, &self
);
456 * Implies mb(), the result of xchg() must be visible
457 * to core_state->dumper.
459 if (atomic_dec_and_test(&core_state
->nr_threads
))
460 complete(&core_state
->startup
);
463 set_current_state(TASK_UNINTERRUPTIBLE
);
464 if (!self
.task
) /* see coredump_finish() */
466 freezable_schedule();
468 __set_current_state(TASK_RUNNING
);
469 down_read(&mm
->mmap_sem
);
472 BUG_ON(mm
!= current
->active_mm
);
473 /* more a memory barrier than a real lock */
476 up_read(&mm
->mmap_sem
);
477 enter_lazy_tlb(mm
, current
);
478 task_unlock(current
);
479 mm_update_next_owner(mm
);
481 if (test_thread_flag(TIF_MEMDIE
))
485 static struct task_struct
*find_alive_thread(struct task_struct
*p
)
487 struct task_struct
*t
;
489 for_each_thread(p
, t
) {
490 if (!(t
->flags
& PF_EXITING
))
496 static struct task_struct
*find_child_reaper(struct task_struct
*father
,
497 struct list_head
*dead
)
498 __releases(&tasklist_lock
)
499 __acquires(&tasklist_lock
)
501 struct pid_namespace
*pid_ns
= task_active_pid_ns(father
);
502 struct task_struct
*reaper
= pid_ns
->child_reaper
;
503 struct task_struct
*p
, *n
;
505 if (likely(reaper
!= father
))
508 reaper
= find_alive_thread(father
);
510 pid_ns
->child_reaper
= reaper
;
514 write_unlock_irq(&tasklist_lock
);
516 list_for_each_entry_safe(p
, n
, dead
, ptrace_entry
) {
517 list_del_init(&p
->ptrace_entry
);
521 zap_pid_ns_processes(pid_ns
);
522 write_lock_irq(&tasklist_lock
);
528 * When we die, we re-parent all our children, and try to:
529 * 1. give them to another thread in our thread group, if such a member exists
530 * 2. give it to the first ancestor process which prctl'd itself as a
531 * child_subreaper for its children (like a service manager)
532 * 3. give it to the init process (PID 1) in our pid namespace
534 static struct task_struct
*find_new_reaper(struct task_struct
*father
,
535 struct task_struct
*child_reaper
)
537 struct task_struct
*thread
, *reaper
;
539 thread
= find_alive_thread(father
);
543 if (father
->signal
->has_child_subreaper
) {
544 unsigned int ns_level
= task_pid(father
)->level
;
546 * Find the first ->is_child_subreaper ancestor in our pid_ns.
547 * We can't check reaper != child_reaper to ensure we do not
548 * cross the namespaces, the exiting parent could be injected
549 * by setns() + fork().
550 * We check pid->level, this is slightly more efficient than
551 * task_active_pid_ns(reaper) != task_active_pid_ns(father).
553 for (reaper
= father
->real_parent
;
554 task_pid(reaper
)->level
== ns_level
;
555 reaper
= reaper
->real_parent
) {
556 if (reaper
== &init_task
)
558 if (!reaper
->signal
->is_child_subreaper
)
560 thread
= find_alive_thread(reaper
);
570 * Any that need to be release_task'd are put on the @dead list.
572 static void reparent_leader(struct task_struct
*father
, struct task_struct
*p
,
573 struct list_head
*dead
)
575 if (unlikely(p
->exit_state
== EXIT_DEAD
))
578 /* We don't want people slaying init. */
579 p
->exit_signal
= SIGCHLD
;
581 /* If it has exited notify the new parent about this child's death. */
583 p
->exit_state
== EXIT_ZOMBIE
&& thread_group_empty(p
)) {
584 if (do_notify_parent(p
, p
->exit_signal
)) {
585 p
->exit_state
= EXIT_DEAD
;
586 list_add(&p
->ptrace_entry
, dead
);
590 kill_orphaned_pgrp(p
, father
);
594 * This does two things:
596 * A. Make init inherit all the child processes
597 * B. Check to see if any process groups have become orphaned
598 * as a result of our exiting, and if they have any stopped
599 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
601 static void forget_original_parent(struct task_struct
*father
,
602 struct list_head
*dead
)
604 struct task_struct
*p
, *t
, *reaper
;
606 if (unlikely(!list_empty(&father
->ptraced
)))
607 exit_ptrace(father
, dead
);
609 /* Can drop and reacquire tasklist_lock */
610 reaper
= find_child_reaper(father
, dead
);
611 if (list_empty(&father
->children
))
614 reaper
= find_new_reaper(father
, reaper
);
615 list_for_each_entry(p
, &father
->children
, sibling
) {
616 for_each_thread(p
, t
) {
617 RCU_INIT_POINTER(t
->real_parent
, reaper
);
618 BUG_ON((!t
->ptrace
) != (rcu_access_pointer(t
->parent
) == father
));
619 if (likely(!t
->ptrace
))
620 t
->parent
= t
->real_parent
;
621 if (t
->pdeath_signal
)
622 group_send_sig_info(t
->pdeath_signal
,
627 * If this is a threaded reparent there is no need to
628 * notify anyone anything has happened.
630 if (!same_thread_group(reaper
, father
))
631 reparent_leader(father
, p
, dead
);
633 list_splice_tail_init(&father
->children
, &reaper
->children
);
637 * Send signals to all our closest relatives so that they know
638 * to properly mourn us..
640 static void exit_notify(struct task_struct
*tsk
, int group_dead
)
643 struct task_struct
*p
, *n
;
646 write_lock_irq(&tasklist_lock
);
647 forget_original_parent(tsk
, &dead
);
650 kill_orphaned_pgrp(tsk
->group_leader
, NULL
);
652 tsk
->exit_state
= EXIT_ZOMBIE
;
653 if (unlikely(tsk
->ptrace
)) {
654 int sig
= thread_group_leader(tsk
) &&
655 thread_group_empty(tsk
) &&
656 !ptrace_reparented(tsk
) ?
657 tsk
->exit_signal
: SIGCHLD
;
658 autoreap
= do_notify_parent(tsk
, sig
);
659 } else if (thread_group_leader(tsk
)) {
660 autoreap
= thread_group_empty(tsk
) &&
661 do_notify_parent(tsk
, tsk
->exit_signal
);
667 tsk
->exit_state
= EXIT_DEAD
;
668 list_add(&tsk
->ptrace_entry
, &dead
);
671 /* mt-exec, de_thread() is waiting for group leader */
672 if (unlikely(tsk
->signal
->notify_count
< 0))
673 wake_up_process(tsk
->signal
->group_exit_task
);
674 write_unlock_irq(&tasklist_lock
);
676 list_for_each_entry_safe(p
, n
, &dead
, ptrace_entry
) {
677 list_del_init(&p
->ptrace_entry
);
682 #ifdef CONFIG_DEBUG_STACK_USAGE
683 static void check_stack_usage(void)
685 static DEFINE_SPINLOCK(low_water_lock
);
686 static int lowest_to_date
= THREAD_SIZE
;
689 free
= stack_not_used(current
);
691 if (free
>= lowest_to_date
)
694 spin_lock(&low_water_lock
);
695 if (free
< lowest_to_date
) {
696 pr_info("%s (%d) used greatest stack depth: %lu bytes left\n",
697 current
->comm
, task_pid_nr(current
), free
);
698 lowest_to_date
= free
;
700 spin_unlock(&low_water_lock
);
703 static inline void check_stack_usage(void) {}
706 void __noreturn
do_exit(long code
)
708 struct task_struct
*tsk
= current
;
711 profile_task_exit(tsk
);
714 WARN_ON(blk_needs_flush_plug(tsk
));
716 if (unlikely(in_interrupt()))
717 panic("Aiee, killing interrupt handler!");
718 if (unlikely(!tsk
->pid
))
719 panic("Attempted to kill the idle task!");
722 * If do_exit is called because this processes oopsed, it's possible
723 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
724 * continuing. Amongst other possible reasons, this is to prevent
725 * mm_release()->clear_child_tid() from writing to a user-controlled
730 ptrace_event(PTRACE_EVENT_EXIT
, code
);
732 validate_creds_for_do_exit(tsk
);
735 * We're taking recursive faults here in do_exit. Safest is to just
736 * leave this task alone and wait for reboot.
738 if (unlikely(tsk
->flags
& PF_EXITING
)) {
739 pr_alert("Fixing recursive fault but reboot is needed!\n");
740 futex_exit_recursive(tsk
);
741 set_current_state(TASK_UNINTERRUPTIBLE
);
745 exit_signals(tsk
); /* sets PF_EXITING */
747 if (unlikely(in_atomic())) {
748 pr_info("note: %s[%d] exited with preempt_count %d\n",
749 current
->comm
, task_pid_nr(current
),
751 preempt_count_set(PREEMPT_ENABLED
);
754 /* sync mm's RSS info before statistics gathering */
756 sync_mm_rss(tsk
->mm
);
757 acct_update_integrals(tsk
);
758 group_dead
= atomic_dec_and_test(&tsk
->signal
->live
);
761 * If the last thread of global init has exited, panic
762 * immediately to get a useable coredump.
764 if (unlikely(is_global_init(tsk
)))
765 panic("Attempted to kill init! exitcode=0x%08x\n",
766 tsk
->signal
->group_exit_code
?: (int)code
);
768 #ifdef CONFIG_POSIX_TIMERS
769 hrtimer_cancel(&tsk
->signal
->real_timer
);
770 exit_itimers(tsk
->signal
);
773 setmax_mm_hiwater_rss(&tsk
->signal
->maxrss
, tsk
->mm
);
775 acct_collect(code
, group_dead
);
780 tsk
->exit_code
= code
;
781 taskstats_exit(tsk
, group_dead
);
787 trace_sched_process_exit(tsk
);
794 disassociate_ctty(1);
795 exit_task_namespaces(tsk
);
801 * Flush inherited counters to the parent - before the parent
802 * gets woken up by child-exit notifications.
804 * because of cgroup mode, must be called before cgroup_exit()
806 perf_event_exit_task(tsk
);
808 sched_autogroup_exit_task(tsk
);
812 * FIXME: do that only when needed, using sched_exit tracepoint
814 flush_ptrace_hw_breakpoint(tsk
);
816 exit_tasks_rcu_start();
817 exit_notify(tsk
, group_dead
);
818 proc_exit_connector(tsk
);
819 mpol_put_task_policy(tsk
);
821 if (unlikely(current
->pi_state_cache
))
822 kfree(current
->pi_state_cache
);
825 * Make sure we are holding no locks:
827 debug_check_no_locks_held();
830 exit_io_context(tsk
);
832 if (tsk
->splice_pipe
)
833 free_pipe_info(tsk
->splice_pipe
);
835 if (tsk
->task_frag
.page
)
836 put_page(tsk
->task_frag
.page
);
838 validate_creds_for_do_exit(tsk
);
843 __this_cpu_add(dirty_throttle_leaks
, tsk
->nr_dirtied
);
845 exit_tasks_rcu_finish();
847 lockdep_free_task(tsk
);
850 EXPORT_SYMBOL_GPL(do_exit
);
852 void complete_and_exit(struct completion
*comp
, long code
)
859 EXPORT_SYMBOL(complete_and_exit
);
861 SYSCALL_DEFINE1(exit
, int, error_code
)
863 do_exit((error_code
&0xff)<<8);
867 * Take down every thread in the group. This is called by fatal signals
868 * as well as by sys_exit_group (below).
871 do_group_exit(int exit_code
)
873 struct signal_struct
*sig
= current
->signal
;
875 BUG_ON(exit_code
& 0x80); /* core dumps don't get here */
877 if (signal_group_exit(sig
))
878 exit_code
= sig
->group_exit_code
;
879 else if (!thread_group_empty(current
)) {
880 struct sighand_struct
*const sighand
= current
->sighand
;
882 spin_lock_irq(&sighand
->siglock
);
883 if (signal_group_exit(sig
))
884 /* Another thread got here before we took the lock. */
885 exit_code
= sig
->group_exit_code
;
887 sig
->group_exit_code
= exit_code
;
888 sig
->flags
= SIGNAL_GROUP_EXIT
;
889 zap_other_threads(current
);
891 spin_unlock_irq(&sighand
->siglock
);
899 * this kills every thread in the thread group. Note that any externally
900 * wait4()-ing process will get the correct exit code - even if this
901 * thread is not the thread group leader.
903 SYSCALL_DEFINE1(exit_group
, int, error_code
)
905 do_group_exit((error_code
& 0xff) << 8);
918 enum pid_type wo_type
;
922 struct waitid_info
*wo_info
;
924 struct rusage
*wo_rusage
;
926 wait_queue_entry_t child_wait
;
930 static int eligible_pid(struct wait_opts
*wo
, struct task_struct
*p
)
932 return wo
->wo_type
== PIDTYPE_MAX
||
933 task_pid_type(p
, wo
->wo_type
) == wo
->wo_pid
;
937 eligible_child(struct wait_opts
*wo
, bool ptrace
, struct task_struct
*p
)
939 if (!eligible_pid(wo
, p
))
943 * Wait for all children (clone and not) if __WALL is set or
944 * if it is traced by us.
946 if (ptrace
|| (wo
->wo_flags
& __WALL
))
950 * Otherwise, wait for clone children *only* if __WCLONE is set;
951 * otherwise, wait for non-clone children *only*.
953 * Note: a "clone" child here is one that reports to its parent
954 * using a signal other than SIGCHLD, or a non-leader thread which
955 * we can only see if it is traced by us.
957 if ((p
->exit_signal
!= SIGCHLD
) ^ !!(wo
->wo_flags
& __WCLONE
))
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
)
972 pid_t pid
= task_pid_vnr(p
);
973 uid_t uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
974 struct waitid_info
*infop
;
976 if (!likely(wo
->wo_flags
& WEXITED
))
979 if (unlikely(wo
->wo_flags
& WNOWAIT
)) {
980 status
= p
->exit_code
;
982 read_unlock(&tasklist_lock
);
983 sched_annotate_sleep();
985 getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
);
990 * Move the task's state to DEAD/TRACE, only one thread can do this.
992 state
= (ptrace_reparented(p
) && thread_group_leader(p
)) ?
993 EXIT_TRACE
: EXIT_DEAD
;
994 if (cmpxchg(&p
->exit_state
, EXIT_ZOMBIE
, state
) != EXIT_ZOMBIE
)
997 * We own this thread, nobody else can reap it.
999 read_unlock(&tasklist_lock
);
1000 sched_annotate_sleep();
1003 * Check thread_group_leader() to exclude the traced sub-threads.
1005 if (state
== EXIT_DEAD
&& thread_group_leader(p
)) {
1006 struct signal_struct
*sig
= p
->signal
;
1007 struct signal_struct
*psig
= current
->signal
;
1008 unsigned long maxrss
;
1009 u64 tgutime
, tgstime
;
1012 * The resource counters for the group leader are in its
1013 * own task_struct. Those for dead threads in the group
1014 * are in its signal_struct, as are those for the child
1015 * processes it has previously reaped. All these
1016 * accumulate in the parent's signal_struct c* fields.
1018 * We don't bother to take a lock here to protect these
1019 * p->signal fields because the whole thread group is dead
1020 * and nobody can change them.
1022 * psig->stats_lock also protects us from our sub-theads
1023 * which can reap other children at the same time. Until
1024 * we change k_getrusage()-like users to rely on this lock
1025 * we have to take ->siglock as well.
1027 * We use thread_group_cputime_adjusted() to get times for
1028 * the thread group, which consolidates times for all threads
1029 * in the group including the group leader.
1031 thread_group_cputime_adjusted(p
, &tgutime
, &tgstime
);
1032 spin_lock_irq(¤t
->sighand
->siglock
);
1033 write_seqlock(&psig
->stats_lock
);
1034 psig
->cutime
+= tgutime
+ sig
->cutime
;
1035 psig
->cstime
+= tgstime
+ sig
->cstime
;
1036 psig
->cgtime
+= task_gtime(p
) + sig
->gtime
+ sig
->cgtime
;
1038 p
->min_flt
+ sig
->min_flt
+ sig
->cmin_flt
;
1040 p
->maj_flt
+ sig
->maj_flt
+ sig
->cmaj_flt
;
1042 p
->nvcsw
+ sig
->nvcsw
+ sig
->cnvcsw
;
1044 p
->nivcsw
+ sig
->nivcsw
+ sig
->cnivcsw
;
1046 task_io_get_inblock(p
) +
1047 sig
->inblock
+ sig
->cinblock
;
1049 task_io_get_oublock(p
) +
1050 sig
->oublock
+ sig
->coublock
;
1051 maxrss
= max(sig
->maxrss
, sig
->cmaxrss
);
1052 if (psig
->cmaxrss
< maxrss
)
1053 psig
->cmaxrss
= maxrss
;
1054 task_io_accounting_add(&psig
->ioac
, &p
->ioac
);
1055 task_io_accounting_add(&psig
->ioac
, &sig
->ioac
);
1056 write_sequnlock(&psig
->stats_lock
);
1057 spin_unlock_irq(¤t
->sighand
->siglock
);
1061 getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
);
1062 status
= (p
->signal
->flags
& SIGNAL_GROUP_EXIT
)
1063 ? p
->signal
->group_exit_code
: p
->exit_code
;
1064 wo
->wo_stat
= status
;
1066 if (state
== EXIT_TRACE
) {
1067 write_lock_irq(&tasklist_lock
);
1068 /* We dropped tasklist, ptracer could die and untrace */
1071 /* If parent wants a zombie, don't release it now */
1072 state
= EXIT_ZOMBIE
;
1073 if (do_notify_parent(p
, p
->exit_signal
))
1075 p
->exit_state
= state
;
1076 write_unlock_irq(&tasklist_lock
);
1078 if (state
== EXIT_DEAD
)
1082 infop
= wo
->wo_info
;
1084 if ((status
& 0x7f) == 0) {
1085 infop
->cause
= CLD_EXITED
;
1086 infop
->status
= status
>> 8;
1088 infop
->cause
= (status
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
1089 infop
->status
= status
& 0x7f;
1098 static int *task_stopped_code(struct task_struct
*p
, bool ptrace
)
1101 if (task_is_traced(p
) && !(p
->jobctl
& JOBCTL_LISTENING
))
1102 return &p
->exit_code
;
1104 if (p
->signal
->flags
& SIGNAL_STOP_STOPPED
)
1105 return &p
->signal
->group_exit_code
;
1111 * wait_task_stopped - Wait for %TASK_STOPPED or %TASK_TRACED
1113 * @ptrace: is the wait for ptrace
1114 * @p: task to wait for
1116 * Handle sys_wait4() work for %p in state %TASK_STOPPED or %TASK_TRACED.
1119 * read_lock(&tasklist_lock), which is released if return value is
1120 * non-zero. Also, grabs and releases @p->sighand->siglock.
1123 * 0 if wait condition didn't exist and search for other wait conditions
1124 * should continue. Non-zero return, -errno on failure and @p's pid on
1125 * success, implies that tasklist_lock is released and wait condition
1126 * search should terminate.
1128 static int wait_task_stopped(struct wait_opts
*wo
,
1129 int ptrace
, struct task_struct
*p
)
1131 struct waitid_info
*infop
;
1132 int exit_code
, *p_code
, why
;
1133 uid_t uid
= 0; /* unneeded, required by compiler */
1137 * Traditionally we see ptrace'd stopped tasks regardless of options.
1139 if (!ptrace
&& !(wo
->wo_flags
& WUNTRACED
))
1142 if (!task_stopped_code(p
, ptrace
))
1146 spin_lock_irq(&p
->sighand
->siglock
);
1148 p_code
= task_stopped_code(p
, ptrace
);
1149 if (unlikely(!p_code
))
1152 exit_code
= *p_code
;
1156 if (!unlikely(wo
->wo_flags
& WNOWAIT
))
1159 uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
1161 spin_unlock_irq(&p
->sighand
->siglock
);
1166 * Now we are pretty sure this task is interesting.
1167 * Make sure it doesn't get reaped out from under us while we
1168 * give up the lock and then examine it below. We don't want to
1169 * keep holding onto the tasklist_lock while we call getrusage and
1170 * possibly take page faults for user memory.
1173 pid
= task_pid_vnr(p
);
1174 why
= ptrace
? CLD_TRAPPED
: CLD_STOPPED
;
1175 read_unlock(&tasklist_lock
);
1176 sched_annotate_sleep();
1178 getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
);
1181 if (likely(!(wo
->wo_flags
& WNOWAIT
)))
1182 wo
->wo_stat
= (exit_code
<< 8) | 0x7f;
1184 infop
= wo
->wo_info
;
1187 infop
->status
= exit_code
;
1195 * Handle do_wait work for one task in a live, non-stopped state.
1196 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1197 * the lock and this task is uninteresting. If we return nonzero, we have
1198 * released the lock and the system call should return.
1200 static int wait_task_continued(struct wait_opts
*wo
, struct task_struct
*p
)
1202 struct waitid_info
*infop
;
1206 if (!unlikely(wo
->wo_flags
& WCONTINUED
))
1209 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
))
1212 spin_lock_irq(&p
->sighand
->siglock
);
1213 /* Re-check with the lock held. */
1214 if (!(p
->signal
->flags
& SIGNAL_STOP_CONTINUED
)) {
1215 spin_unlock_irq(&p
->sighand
->siglock
);
1218 if (!unlikely(wo
->wo_flags
& WNOWAIT
))
1219 p
->signal
->flags
&= ~SIGNAL_STOP_CONTINUED
;
1220 uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
1221 spin_unlock_irq(&p
->sighand
->siglock
);
1223 pid
= task_pid_vnr(p
);
1225 read_unlock(&tasklist_lock
);
1226 sched_annotate_sleep();
1228 getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
);
1231 infop
= wo
->wo_info
;
1233 wo
->wo_stat
= 0xffff;
1235 infop
->cause
= CLD_CONTINUED
;
1238 infop
->status
= SIGCONT
;
1244 * Consider @p for a wait by @parent.
1246 * -ECHILD should be in ->notask_error before the first call.
1247 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1248 * Returns zero if the search for a child should continue;
1249 * then ->notask_error is 0 if @p is an eligible child,
1252 static int wait_consider_task(struct wait_opts
*wo
, int ptrace
,
1253 struct task_struct
*p
)
1256 * We can race with wait_task_zombie() from another thread.
1257 * Ensure that EXIT_ZOMBIE -> EXIT_DEAD/EXIT_TRACE transition
1258 * can't confuse the checks below.
1260 int exit_state
= READ_ONCE(p
->exit_state
);
1263 if (unlikely(exit_state
== EXIT_DEAD
))
1266 ret
= eligible_child(wo
, ptrace
, p
);
1270 if (unlikely(exit_state
== EXIT_TRACE
)) {
1272 * ptrace == 0 means we are the natural parent. In this case
1273 * we should clear notask_error, debugger will notify us.
1275 if (likely(!ptrace
))
1276 wo
->notask_error
= 0;
1280 if (likely(!ptrace
) && unlikely(p
->ptrace
)) {
1282 * If it is traced by its real parent's group, just pretend
1283 * the caller is ptrace_do_wait() and reap this child if it
1286 * This also hides group stop state from real parent; otherwise
1287 * a single stop can be reported twice as group and ptrace stop.
1288 * If a ptracer wants to distinguish these two events for its
1289 * own children it should create a separate process which takes
1290 * the role of real parent.
1292 if (!ptrace_reparented(p
))
1297 if (exit_state
== EXIT_ZOMBIE
) {
1298 /* we don't reap group leaders with subthreads */
1299 if (!delay_group_leader(p
)) {
1301 * A zombie ptracee is only visible to its ptracer.
1302 * Notification and reaping will be cascaded to the
1303 * real parent when the ptracer detaches.
1305 if (unlikely(ptrace
) || likely(!p
->ptrace
))
1306 return wait_task_zombie(wo
, p
);
1310 * Allow access to stopped/continued state via zombie by
1311 * falling through. Clearing of notask_error is complex.
1315 * If WEXITED is set, notask_error should naturally be
1316 * cleared. If not, subset of WSTOPPED|WCONTINUED is set,
1317 * so, if there are live subthreads, there are events to
1318 * wait for. If all subthreads are dead, it's still safe
1319 * to clear - this function will be called again in finite
1320 * amount time once all the subthreads are released and
1321 * will then return without clearing.
1325 * Stopped state is per-task and thus can't change once the
1326 * target task dies. Only continued and exited can happen.
1327 * Clear notask_error if WCONTINUED | WEXITED.
1329 if (likely(!ptrace
) || (wo
->wo_flags
& (WCONTINUED
| WEXITED
)))
1330 wo
->notask_error
= 0;
1333 * @p is alive and it's gonna stop, continue or exit, so
1334 * there always is something to wait for.
1336 wo
->notask_error
= 0;
1340 * Wait for stopped. Depending on @ptrace, different stopped state
1341 * is used and the two don't interact with each other.
1343 ret
= wait_task_stopped(wo
, ptrace
, p
);
1348 * Wait for continued. There's only one continued state and the
1349 * ptracer can consume it which can confuse the real parent. Don't
1350 * use WCONTINUED from ptracer. You don't need or want it.
1352 return wait_task_continued(wo
, p
);
1356 * Do the work of do_wait() for one thread in the group, @tsk.
1358 * -ECHILD should be in ->notask_error before the first call.
1359 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1360 * Returns zero if the search for a child should continue; then
1361 * ->notask_error is 0 if there were any eligible children,
1364 static int do_wait_thread(struct wait_opts
*wo
, struct task_struct
*tsk
)
1366 struct task_struct
*p
;
1368 list_for_each_entry(p
, &tsk
->children
, sibling
) {
1369 int ret
= wait_consider_task(wo
, 0, p
);
1378 static int ptrace_do_wait(struct wait_opts
*wo
, struct task_struct
*tsk
)
1380 struct task_struct
*p
;
1382 list_for_each_entry(p
, &tsk
->ptraced
, ptrace_entry
) {
1383 int ret
= wait_consider_task(wo
, 1, p
);
1392 static int child_wait_callback(wait_queue_entry_t
*wait
, unsigned mode
,
1393 int sync
, void *key
)
1395 struct wait_opts
*wo
= container_of(wait
, struct wait_opts
,
1397 struct task_struct
*p
= key
;
1399 if (!eligible_pid(wo
, p
))
1402 if ((wo
->wo_flags
& __WNOTHREAD
) && wait
->private != p
->parent
)
1405 return default_wake_function(wait
, mode
, sync
, key
);
1408 void __wake_up_parent(struct task_struct
*p
, struct task_struct
*parent
)
1410 __wake_up_sync_key(&parent
->signal
->wait_chldexit
,
1411 TASK_INTERRUPTIBLE
, p
);
1414 static long do_wait(struct wait_opts
*wo
)
1416 struct task_struct
*tsk
;
1419 trace_sched_process_wait(wo
->wo_pid
);
1421 init_waitqueue_func_entry(&wo
->child_wait
, child_wait_callback
);
1422 wo
->child_wait
.private = current
;
1423 add_wait_queue(¤t
->signal
->wait_chldexit
, &wo
->child_wait
);
1426 * If there is nothing that can match our criteria, just get out.
1427 * We will clear ->notask_error to zero if we see any child that
1428 * might later match our criteria, even if we are not able to reap
1431 wo
->notask_error
= -ECHILD
;
1432 if ((wo
->wo_type
< PIDTYPE_MAX
) &&
1433 (!wo
->wo_pid
|| !pid_has_task(wo
->wo_pid
, wo
->wo_type
)))
1436 set_current_state(TASK_INTERRUPTIBLE
);
1437 read_lock(&tasklist_lock
);
1440 retval
= do_wait_thread(wo
, tsk
);
1444 retval
= ptrace_do_wait(wo
, tsk
);
1448 if (wo
->wo_flags
& __WNOTHREAD
)
1450 } while_each_thread(current
, tsk
);
1451 read_unlock(&tasklist_lock
);
1454 retval
= wo
->notask_error
;
1455 if (!retval
&& !(wo
->wo_flags
& WNOHANG
)) {
1456 retval
= -ERESTARTSYS
;
1457 if (!signal_pending(current
)) {
1463 __set_current_state(TASK_RUNNING
);
1464 remove_wait_queue(¤t
->signal
->wait_chldexit
, &wo
->child_wait
);
1468 static struct pid
*pidfd_get_pid(unsigned int fd
)
1475 return ERR_PTR(-EBADF
);
1477 pid
= pidfd_pid(f
.file
);
1485 static long kernel_waitid(int which
, pid_t upid
, struct waitid_info
*infop
,
1486 int options
, struct rusage
*ru
)
1488 struct wait_opts wo
;
1489 struct pid
*pid
= NULL
;
1493 if (options
& ~(WNOHANG
|WNOWAIT
|WEXITED
|WSTOPPED
|WCONTINUED
|
1494 __WNOTHREAD
|__WCLONE
|__WALL
))
1496 if (!(options
& (WEXITED
|WSTOPPED
|WCONTINUED
)))
1508 pid
= find_get_pid(upid
);
1511 type
= PIDTYPE_PGID
;
1516 pid
= find_get_pid(upid
);
1518 pid
= get_task_pid(current
, PIDTYPE_PGID
);
1525 pid
= pidfd_get_pid(upid
);
1527 return PTR_ERR(pid
);
1535 wo
.wo_flags
= options
;
1544 SYSCALL_DEFINE5(waitid
, int, which
, pid_t
, upid
, struct siginfo __user
*,
1545 infop
, int, options
, struct rusage __user
*, ru
)
1548 struct waitid_info info
= {.status
= 0};
1549 long err
= kernel_waitid(which
, upid
, &info
, options
, ru
? &r
: NULL
);
1555 if (ru
&& copy_to_user(ru
, &r
, sizeof(struct rusage
)))
1561 if (!user_write_access_begin(infop
, sizeof(*infop
)))
1564 unsafe_put_user(signo
, &infop
->si_signo
, Efault
);
1565 unsafe_put_user(0, &infop
->si_errno
, Efault
);
1566 unsafe_put_user(info
.cause
, &infop
->si_code
, Efault
);
1567 unsafe_put_user(info
.pid
, &infop
->si_pid
, Efault
);
1568 unsafe_put_user(info
.uid
, &infop
->si_uid
, Efault
);
1569 unsafe_put_user(info
.status
, &infop
->si_status
, Efault
);
1570 user_write_access_end();
1573 user_write_access_end();
1577 long kernel_wait4(pid_t upid
, int __user
*stat_addr
, int options
,
1580 struct wait_opts wo
;
1581 struct pid
*pid
= NULL
;
1585 if (options
& ~(WNOHANG
|WUNTRACED
|WCONTINUED
|
1586 __WNOTHREAD
|__WCLONE
|__WALL
))
1589 /* -INT_MIN is not defined */
1590 if (upid
== INT_MIN
)
1595 else if (upid
< 0) {
1596 type
= PIDTYPE_PGID
;
1597 pid
= find_get_pid(-upid
);
1598 } else if (upid
== 0) {
1599 type
= PIDTYPE_PGID
;
1600 pid
= get_task_pid(current
, PIDTYPE_PGID
);
1601 } else /* upid > 0 */ {
1603 pid
= find_get_pid(upid
);
1608 wo
.wo_flags
= options
| WEXITED
;
1614 if (ret
> 0 && stat_addr
&& put_user(wo
.wo_stat
, stat_addr
))
1620 SYSCALL_DEFINE4(wait4
, pid_t
, upid
, int __user
*, stat_addr
,
1621 int, options
, struct rusage __user
*, ru
)
1624 long err
= kernel_wait4(upid
, stat_addr
, options
, ru
? &r
: NULL
);
1627 if (ru
&& copy_to_user(ru
, &r
, sizeof(struct rusage
)))
1633 #ifdef __ARCH_WANT_SYS_WAITPID
1636 * sys_waitpid() remains for compatibility. waitpid() should be
1637 * implemented by calling sys_wait4() from libc.a.
1639 SYSCALL_DEFINE3(waitpid
, pid_t
, pid
, int __user
*, stat_addr
, int, options
)
1641 return kernel_wait4(pid
, stat_addr
, options
, NULL
);
1646 #ifdef CONFIG_COMPAT
1647 COMPAT_SYSCALL_DEFINE4(wait4
,
1649 compat_uint_t __user
*, stat_addr
,
1651 struct compat_rusage __user
*, ru
)
1654 long err
= kernel_wait4(pid
, stat_addr
, options
, ru
? &r
: NULL
);
1656 if (ru
&& put_compat_rusage(&r
, ru
))
1662 COMPAT_SYSCALL_DEFINE5(waitid
,
1663 int, which
, compat_pid_t
, pid
,
1664 struct compat_siginfo __user
*, infop
, int, options
,
1665 struct compat_rusage __user
*, uru
)
1668 struct waitid_info info
= {.status
= 0};
1669 long err
= kernel_waitid(which
, pid
, &info
, options
, uru
? &ru
: NULL
);
1675 /* kernel_waitid() overwrites everything in ru */
1676 if (COMPAT_USE_64BIT_TIME
)
1677 err
= copy_to_user(uru
, &ru
, sizeof(ru
));
1679 err
= put_compat_rusage(&ru
, uru
);
1688 if (!user_write_access_begin(infop
, sizeof(*infop
)))
1691 unsafe_put_user(signo
, &infop
->si_signo
, Efault
);
1692 unsafe_put_user(0, &infop
->si_errno
, Efault
);
1693 unsafe_put_user(info
.cause
, &infop
->si_code
, Efault
);
1694 unsafe_put_user(info
.pid
, &infop
->si_pid
, Efault
);
1695 unsafe_put_user(info
.uid
, &infop
->si_uid
, Efault
);
1696 unsafe_put_user(info
.status
, &infop
->si_status
, Efault
);
1697 user_write_access_end();
1700 user_write_access_end();
1705 __weak
void abort(void)
1709 /* if that doesn't kill us, halt */
1710 panic("Oops failed to kill thread");
1712 EXPORT_SYMBOL(abort
);