]>
git.proxmox.com Git - mirror_ubuntu-zesty-kernel.git/blob - kernel/exit.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
8 #include <linux/slab.h>
9 #include <linux/interrupt.h>
10 #include <linux/module.h>
11 #include <linux/capability.h>
12 #include <linux/completion.h>
13 #include <linux/personality.h>
14 #include <linux/tty.h>
15 #include <linux/iocontext.h>
16 #include <linux/key.h>
17 #include <linux/security.h>
18 #include <linux/cpu.h>
19 #include <linux/acct.h>
20 #include <linux/tsacct_kern.h>
21 #include <linux/file.h>
22 #include <linux/fdtable.h>
23 #include <linux/freezer.h>
24 #include <linux/binfmts.h>
25 #include <linux/nsproxy.h>
26 #include <linux/pid_namespace.h>
27 #include <linux/ptrace.h>
28 #include <linux/profile.h>
29 #include <linux/mount.h>
30 #include <linux/proc_fs.h>
31 #include <linux/kthread.h>
32 #include <linux/mempolicy.h>
33 #include <linux/taskstats_kern.h>
34 #include <linux/delayacct.h>
35 #include <linux/cgroup.h>
36 #include <linux/syscalls.h>
37 #include <linux/signal.h>
38 #include <linux/posix-timers.h>
39 #include <linux/cn_proc.h>
40 #include <linux/mutex.h>
41 #include <linux/futex.h>
42 #include <linux/pipe_fs_i.h>
43 #include <linux/audit.h> /* for audit_free() */
44 #include <linux/resource.h>
45 #include <linux/blkdev.h>
46 #include <linux/task_io_accounting_ops.h>
47 #include <linux/tracehook.h>
48 #include <linux/fs_struct.h>
49 #include <linux/init_task.h>
50 #include <linux/perf_event.h>
51 #include <trace/events/sched.h>
52 #include <linux/hw_breakpoint.h>
53 #include <linux/oom.h>
54 #include <linux/writeback.h>
55 #include <linux/shm.h>
57 #include <asm/uaccess.h>
58 #include <asm/unistd.h>
59 #include <asm/pgtable.h>
60 #include <asm/mmu_context.h>
62 static void exit_mm(struct task_struct
*tsk
);
64 static void __unhash_process(struct task_struct
*p
, bool group_dead
)
67 detach_pid(p
, PIDTYPE_PID
);
69 detach_pid(p
, PIDTYPE_PGID
);
70 detach_pid(p
, PIDTYPE_SID
);
72 list_del_rcu(&p
->tasks
);
73 list_del_init(&p
->sibling
);
74 __this_cpu_dec(process_counts
);
76 list_del_rcu(&p
->thread_group
);
77 list_del_rcu(&p
->thread_node
);
81 * This function expects the tasklist_lock write-locked.
83 static void __exit_signal(struct task_struct
*tsk
)
85 struct signal_struct
*sig
= tsk
->signal
;
86 bool group_dead
= thread_group_leader(tsk
);
87 struct sighand_struct
*sighand
;
88 struct tty_struct
*uninitialized_var(tty
);
89 cputime_t utime
, stime
;
91 sighand
= rcu_dereference_check(tsk
->sighand
,
92 lockdep_tasklist_lock_is_held());
93 spin_lock(&sighand
->siglock
);
95 posix_cpu_timers_exit(tsk
);
97 posix_cpu_timers_exit_group(tsk
);
102 * This can only happen if the caller is de_thread().
103 * FIXME: this is the temporary hack, we should teach
104 * posix-cpu-timers to handle this case correctly.
106 if (unlikely(has_group_leader_pid(tsk
)))
107 posix_cpu_timers_exit_group(tsk
);
110 * If there is any task waiting for the group exit
113 if (sig
->notify_count
> 0 && !--sig
->notify_count
)
114 wake_up_process(sig
->group_exit_task
);
116 if (tsk
== sig
->curr_target
)
117 sig
->curr_target
= next_thread(tsk
);
121 * Accumulate here the counters for all threads as they die. We could
122 * skip the group leader because it is the last user of signal_struct,
123 * but we want to avoid the race with thread_group_cputime() which can
124 * see the empty ->thread_head list.
126 task_cputime(tsk
, &utime
, &stime
);
127 write_seqlock(&sig
->stats_lock
);
130 sig
->gtime
+= task_gtime(tsk
);
131 sig
->min_flt
+= tsk
->min_flt
;
132 sig
->maj_flt
+= tsk
->maj_flt
;
133 sig
->nvcsw
+= tsk
->nvcsw
;
134 sig
->nivcsw
+= tsk
->nivcsw
;
135 sig
->inblock
+= task_io_get_inblock(tsk
);
136 sig
->oublock
+= task_io_get_oublock(tsk
);
137 task_io_accounting_add(&sig
->ioac
, &tsk
->ioac
);
138 sig
->sum_sched_runtime
+= tsk
->se
.sum_exec_runtime
;
140 __unhash_process(tsk
, group_dead
);
141 write_sequnlock(&sig
->stats_lock
);
144 * Do this under ->siglock, we can race with another thread
145 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
147 flush_sigqueue(&tsk
->pending
);
149 spin_unlock(&sighand
->siglock
);
151 __cleanup_sighand(sighand
);
152 clear_tsk_thread_flag(tsk
, TIF_SIGPENDING
);
154 flush_sigqueue(&sig
->shared_pending
);
159 static void delayed_put_task_struct(struct rcu_head
*rhp
)
161 struct task_struct
*tsk
= container_of(rhp
, struct task_struct
, rcu
);
163 perf_event_delayed_put(tsk
);
164 trace_sched_process_free(tsk
);
165 put_task_struct(tsk
);
169 void release_task(struct task_struct
*p
)
171 struct task_struct
*leader
;
174 /* don't need to get the RCU readlock here - the process is dead and
175 * can't be modifying its own credentials. But shut RCU-lockdep up */
177 atomic_dec(&__task_cred(p
)->user
->processes
);
182 write_lock_irq(&tasklist_lock
);
183 ptrace_release_task(p
);
187 * If we are the last non-leader member of the thread
188 * group, and the leader is zombie, then notify the
189 * group leader's parent process. (if it wants notification.)
192 leader
= p
->group_leader
;
193 if (leader
!= p
&& thread_group_empty(leader
)
194 && leader
->exit_state
== EXIT_ZOMBIE
) {
196 * If we were the last child thread and the leader has
197 * exited already, and the leader's parent ignores SIGCHLD,
198 * then we are the one who should release the leader.
200 zap_leader
= do_notify_parent(leader
, leader
->exit_signal
);
202 leader
->exit_state
= EXIT_DEAD
;
205 write_unlock_irq(&tasklist_lock
);
207 call_rcu(&p
->rcu
, delayed_put_task_struct
);
210 if (unlikely(zap_leader
))
215 * Determine if a process group is "orphaned", according to the POSIX
216 * definition in 2.2.2.52. Orphaned process groups are not to be affected
217 * by terminal-generated stop signals. Newly orphaned process groups are
218 * to receive a SIGHUP and a SIGCONT.
220 * "I ask you, have you ever known what it is to be an orphan?"
222 static int will_become_orphaned_pgrp(struct pid
*pgrp
,
223 struct task_struct
*ignored_task
)
225 struct task_struct
*p
;
227 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
228 if ((p
== ignored_task
) ||
229 (p
->exit_state
&& thread_group_empty(p
)) ||
230 is_global_init(p
->real_parent
))
233 if (task_pgrp(p
->real_parent
) != pgrp
&&
234 task_session(p
->real_parent
) == task_session(p
))
236 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
241 int is_current_pgrp_orphaned(void)
245 read_lock(&tasklist_lock
);
246 retval
= will_become_orphaned_pgrp(task_pgrp(current
), NULL
);
247 read_unlock(&tasklist_lock
);
252 static bool has_stopped_jobs(struct pid
*pgrp
)
254 struct task_struct
*p
;
256 do_each_pid_task(pgrp
, PIDTYPE_PGID
, p
) {
257 if (p
->signal
->flags
& SIGNAL_STOP_STOPPED
)
259 } while_each_pid_task(pgrp
, PIDTYPE_PGID
, p
);
265 * Check to see if any process groups have become orphaned as
266 * a result of our exiting, and if they have any stopped jobs,
267 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
270 kill_orphaned_pgrp(struct task_struct
*tsk
, struct task_struct
*parent
)
272 struct pid
*pgrp
= task_pgrp(tsk
);
273 struct task_struct
*ignored_task
= tsk
;
276 /* exit: our father is in a different pgrp than
277 * we are and we were the only connection outside.
279 parent
= tsk
->real_parent
;
281 /* reparent: our child is in a different pgrp than
282 * we are, and it was the only connection outside.
286 if (task_pgrp(parent
) != pgrp
&&
287 task_session(parent
) == task_session(tsk
) &&
288 will_become_orphaned_pgrp(pgrp
, ignored_task
) &&
289 has_stopped_jobs(pgrp
)) {
290 __kill_pgrp_info(SIGHUP
, SEND_SIG_PRIV
, pgrp
);
291 __kill_pgrp_info(SIGCONT
, SEND_SIG_PRIV
, pgrp
);
297 * A task is exiting. If it owned this mm, find a new owner for the mm.
299 void mm_update_next_owner(struct mm_struct
*mm
)
301 struct task_struct
*c
, *g
, *p
= current
;
305 * If the exiting or execing task is not the owner, it's
306 * someone else's problem.
311 * The current owner is exiting/execing and there are no other
312 * candidates. Do not leave the mm pointing to a possibly
313 * freed task structure.
315 if (atomic_read(&mm
->mm_users
) <= 1) {
320 read_lock(&tasklist_lock
);
322 * Search in the children
324 list_for_each_entry(c
, &p
->children
, sibling
) {
326 goto assign_new_owner
;
330 * Search in the siblings
332 list_for_each_entry(c
, &p
->real_parent
->children
, sibling
) {
334 goto assign_new_owner
;
338 * Search through everything else, we should not get here often.
340 for_each_process(g
) {
341 if (g
->flags
& PF_KTHREAD
)
343 for_each_thread(g
, c
) {
345 goto assign_new_owner
;
350 read_unlock(&tasklist_lock
);
352 * We found no owner yet mm_users > 1: this implies that we are
353 * most likely racing with swapoff (try_to_unuse()) or /proc or
354 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
363 * The task_lock protects c->mm from changing.
364 * We always want mm->owner->mm == mm
368 * Delay read_unlock() till we have the task_lock()
369 * to ensure that c does not slip away underneath us
371 read_unlock(&tasklist_lock
);
381 #endif /* CONFIG_MEMCG */
384 * Turn us into a lazy TLB process if we
387 static void exit_mm(struct task_struct
*tsk
)
389 struct mm_struct
*mm
= tsk
->mm
;
390 struct core_state
*core_state
;
397 * Serialize with any possible pending coredump.
398 * We must hold mmap_sem around checking core_state
399 * and clearing tsk->mm. The core-inducing thread
400 * will increment ->nr_threads for each thread in the
401 * group with ->mm != NULL.
403 down_read(&mm
->mmap_sem
);
404 core_state
= mm
->core_state
;
406 struct core_thread self
;
408 up_read(&mm
->mmap_sem
);
411 self
.next
= xchg(&core_state
->dumper
.next
, &self
);
413 * Implies mb(), the result of xchg() must be visible
414 * to core_state->dumper.
416 if (atomic_dec_and_test(&core_state
->nr_threads
))
417 complete(&core_state
->startup
);
420 set_task_state(tsk
, TASK_UNINTERRUPTIBLE
);
421 if (!self
.task
) /* see coredump_finish() */
423 freezable_schedule();
425 __set_task_state(tsk
, TASK_RUNNING
);
426 down_read(&mm
->mmap_sem
);
428 atomic_inc(&mm
->mm_count
);
429 BUG_ON(mm
!= tsk
->active_mm
);
430 /* more a memory barrier than a real lock */
433 up_read(&mm
->mmap_sem
);
434 enter_lazy_tlb(mm
, current
);
436 mm_update_next_owner(mm
);
438 clear_thread_flag(TIF_MEMDIE
);
441 static struct task_struct
*find_alive_thread(struct task_struct
*p
)
443 struct task_struct
*t
;
445 for_each_thread(p
, t
) {
446 if (!(t
->flags
& PF_EXITING
))
452 static struct task_struct
*find_child_reaper(struct task_struct
*father
)
453 __releases(&tasklist_lock
)
454 __acquires(&tasklist_lock
)
456 struct pid_namespace
*pid_ns
= task_active_pid_ns(father
);
457 struct task_struct
*reaper
= pid_ns
->child_reaper
;
459 if (likely(reaper
!= father
))
462 reaper
= find_alive_thread(father
);
464 pid_ns
->child_reaper
= reaper
;
468 write_unlock_irq(&tasklist_lock
);
469 if (unlikely(pid_ns
== &init_pid_ns
)) {
470 panic("Attempted to kill init! exitcode=0x%08x\n",
471 father
->signal
->group_exit_code
?: father
->exit_code
);
473 zap_pid_ns_processes(pid_ns
);
474 write_lock_irq(&tasklist_lock
);
480 * When we die, we re-parent all our children, and try to:
481 * 1. give them to another thread in our thread group, if such a member exists
482 * 2. give it to the first ancestor process which prctl'd itself as a
483 * child_subreaper for its children (like a service manager)
484 * 3. give it to the init process (PID 1) in our pid namespace
486 static struct task_struct
*find_new_reaper(struct task_struct
*father
,
487 struct task_struct
*child_reaper
)
489 struct task_struct
*thread
, *reaper
;
491 thread
= find_alive_thread(father
);
495 if (father
->signal
->has_child_subreaper
) {
497 * Find the first ->is_child_subreaper ancestor in our pid_ns.
498 * We start from father to ensure we can not look into another
499 * namespace, this is safe because all its threads are dead.
501 for (reaper
= father
;
502 !same_thread_group(reaper
, child_reaper
);
503 reaper
= reaper
->real_parent
) {
504 /* call_usermodehelper() descendants need this check */
505 if (reaper
== &init_task
)
507 if (!reaper
->signal
->is_child_subreaper
)
509 thread
= find_alive_thread(reaper
);
519 * Any that need to be release_task'd are put on the @dead list.
521 static void reparent_leader(struct task_struct
*father
, struct task_struct
*p
,
522 struct list_head
*dead
)
524 if (unlikely(p
->exit_state
== EXIT_DEAD
))
527 /* We don't want people slaying init. */
528 p
->exit_signal
= SIGCHLD
;
530 /* If it has exited notify the new parent about this child's death. */
532 p
->exit_state
== EXIT_ZOMBIE
&& thread_group_empty(p
)) {
533 if (do_notify_parent(p
, p
->exit_signal
)) {
534 p
->exit_state
= EXIT_DEAD
;
535 list_add(&p
->ptrace_entry
, dead
);
539 kill_orphaned_pgrp(p
, father
);
543 * This does two things:
545 * A. Make init inherit all the child processes
546 * B. Check to see if any process groups have become orphaned
547 * as a result of our exiting, and if they have any stopped
548 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
550 static void forget_original_parent(struct task_struct
*father
,
551 struct list_head
*dead
)
553 struct task_struct
*p
, *t
, *reaper
;
555 if (unlikely(!list_empty(&father
->ptraced
)))
556 exit_ptrace(father
, dead
);
558 /* Can drop and reacquire tasklist_lock */
559 reaper
= find_child_reaper(father
);
560 if (list_empty(&father
->children
))
563 reaper
= find_new_reaper(father
, reaper
);
564 list_for_each_entry(p
, &father
->children
, sibling
) {
565 for_each_thread(p
, t
) {
566 t
->real_parent
= reaper
;
567 BUG_ON((!t
->ptrace
) != (t
->parent
== father
));
568 if (likely(!t
->ptrace
))
569 t
->parent
= t
->real_parent
;
570 if (t
->pdeath_signal
)
571 group_send_sig_info(t
->pdeath_signal
,
575 * If this is a threaded reparent there is no need to
576 * notify anyone anything has happened.
578 if (!same_thread_group(reaper
, father
))
579 reparent_leader(father
, p
, dead
);
581 list_splice_tail_init(&father
->children
, &reaper
->children
);
585 * Send signals to all our closest relatives so that they know
586 * to properly mourn us..
588 static void exit_notify(struct task_struct
*tsk
, int group_dead
)
591 struct task_struct
*p
, *n
;
594 write_lock_irq(&tasklist_lock
);
595 forget_original_parent(tsk
, &dead
);
598 kill_orphaned_pgrp(tsk
->group_leader
, NULL
);
600 if (unlikely(tsk
->ptrace
)) {
601 int sig
= thread_group_leader(tsk
) &&
602 thread_group_empty(tsk
) &&
603 !ptrace_reparented(tsk
) ?
604 tsk
->exit_signal
: SIGCHLD
;
605 autoreap
= do_notify_parent(tsk
, sig
);
606 } else if (thread_group_leader(tsk
)) {
607 autoreap
= thread_group_empty(tsk
) &&
608 do_notify_parent(tsk
, tsk
->exit_signal
);
613 tsk
->exit_state
= autoreap
? EXIT_DEAD
: EXIT_ZOMBIE
;
614 if (tsk
->exit_state
== EXIT_DEAD
)
615 list_add(&tsk
->ptrace_entry
, &dead
);
617 /* mt-exec, de_thread() is waiting for group leader */
618 if (unlikely(tsk
->signal
->notify_count
< 0))
619 wake_up_process(tsk
->signal
->group_exit_task
);
620 write_unlock_irq(&tasklist_lock
);
622 list_for_each_entry_safe(p
, n
, &dead
, ptrace_entry
) {
623 list_del_init(&p
->ptrace_entry
);
628 #ifdef CONFIG_DEBUG_STACK_USAGE
629 static void check_stack_usage(void)
631 static DEFINE_SPINLOCK(low_water_lock
);
632 static int lowest_to_date
= THREAD_SIZE
;
635 free
= stack_not_used(current
);
637 if (free
>= lowest_to_date
)
640 spin_lock(&low_water_lock
);
641 if (free
< lowest_to_date
) {
642 pr_warn("%s (%d) used greatest stack depth: %lu bytes left\n",
643 current
->comm
, task_pid_nr(current
), free
);
644 lowest_to_date
= free
;
646 spin_unlock(&low_water_lock
);
649 static inline void check_stack_usage(void) {}
652 void do_exit(long code
)
654 struct task_struct
*tsk
= current
;
656 TASKS_RCU(int tasks_rcu_i
);
658 profile_task_exit(tsk
);
660 WARN_ON(blk_needs_flush_plug(tsk
));
662 if (unlikely(in_interrupt()))
663 panic("Aiee, killing interrupt handler!");
664 if (unlikely(!tsk
->pid
))
665 panic("Attempted to kill the idle task!");
668 * If do_exit is called because this processes oopsed, it's possible
669 * that get_fs() was left as KERNEL_DS, so reset it to USER_DS before
670 * continuing. Amongst other possible reasons, this is to prevent
671 * mm_release()->clear_child_tid() from writing to a user-controlled
676 ptrace_event(PTRACE_EVENT_EXIT
, code
);
678 validate_creds_for_do_exit(tsk
);
681 * We're taking recursive faults here in do_exit. Safest is to just
682 * leave this task alone and wait for reboot.
684 if (unlikely(tsk
->flags
& PF_EXITING
)) {
685 pr_alert("Fixing recursive fault but reboot is needed!\n");
687 * We can do this unlocked here. The futex code uses
688 * this flag just to verify whether the pi state
689 * cleanup has been done or not. In the worst case it
690 * loops once more. We pretend that the cleanup was
691 * done as there is no way to return. Either the
692 * OWNER_DIED bit is set by now or we push the blocked
693 * task into the wait for ever nirwana as well.
695 tsk
->flags
|= PF_EXITPIDONE
;
696 set_current_state(TASK_UNINTERRUPTIBLE
);
700 exit_signals(tsk
); /* sets PF_EXITING */
702 * tsk->flags are checked in the futex code to protect against
703 * an exiting task cleaning up the robust pi futexes.
706 raw_spin_unlock_wait(&tsk
->pi_lock
);
708 if (unlikely(in_atomic()))
709 pr_info("note: %s[%d] exited with preempt_count %d\n",
710 current
->comm
, task_pid_nr(current
),
713 acct_update_integrals(tsk
);
714 /* sync mm's RSS info before statistics gathering */
716 sync_mm_rss(tsk
->mm
);
717 group_dead
= atomic_dec_and_test(&tsk
->signal
->live
);
719 hrtimer_cancel(&tsk
->signal
->real_timer
);
720 exit_itimers(tsk
->signal
);
722 setmax_mm_hiwater_rss(&tsk
->signal
->maxrss
, tsk
->mm
);
724 acct_collect(code
, group_dead
);
729 tsk
->exit_code
= code
;
730 taskstats_exit(tsk
, group_dead
);
736 trace_sched_process_exit(tsk
);
743 disassociate_ctty(1);
744 exit_task_namespaces(tsk
);
749 * Flush inherited counters to the parent - before the parent
750 * gets woken up by child-exit notifications.
752 * because of cgroup mode, must be called before cgroup_exit()
754 perf_event_exit_task(tsk
);
758 module_put(task_thread_info(tsk
)->exec_domain
->module
);
761 * FIXME: do that only when needed, using sched_exit tracepoint
763 flush_ptrace_hw_breakpoint(tsk
);
765 TASKS_RCU(tasks_rcu_i
= __srcu_read_lock(&tasks_rcu_exit_srcu
));
766 exit_notify(tsk
, group_dead
);
767 proc_exit_connector(tsk
);
770 mpol_put(tsk
->mempolicy
);
771 tsk
->mempolicy
= NULL
;
775 if (unlikely(current
->pi_state_cache
))
776 kfree(current
->pi_state_cache
);
779 * Make sure we are holding no locks:
781 debug_check_no_locks_held();
783 * We can do this unlocked here. The futex code uses this flag
784 * just to verify whether the pi state cleanup has been done
785 * or not. In the worst case it loops once more.
787 tsk
->flags
|= PF_EXITPIDONE
;
790 exit_io_context(tsk
);
792 if (tsk
->splice_pipe
)
793 free_pipe_info(tsk
->splice_pipe
);
795 if (tsk
->task_frag
.page
)
796 put_page(tsk
->task_frag
.page
);
798 validate_creds_for_do_exit(tsk
);
803 __this_cpu_add(dirty_throttle_leaks
, tsk
->nr_dirtied
);
805 TASKS_RCU(__srcu_read_unlock(&tasks_rcu_exit_srcu
, tasks_rcu_i
));
808 * The setting of TASK_RUNNING by try_to_wake_up() may be delayed
809 * when the following two conditions become true.
810 * - There is race condition of mmap_sem (It is acquired by
812 * - SMI occurs before setting TASK_RUNINNG.
813 * (or hypervisor of virtual machine switches to other guest)
814 * As a result, we may become TASK_RUNNING after becoming TASK_DEAD
816 * To avoid it, we have to wait for releasing tsk->pi_lock which
817 * is held by try_to_wake_up()
820 raw_spin_unlock_wait(&tsk
->pi_lock
);
822 /* causes final put_task_struct in finish_task_switch(). */
823 tsk
->state
= TASK_DEAD
;
824 tsk
->flags
|= PF_NOFREEZE
; /* tell freezer to ignore us */
827 /* Avoid "noreturn function does return". */
829 cpu_relax(); /* For when BUG is null */
831 EXPORT_SYMBOL_GPL(do_exit
);
833 void complete_and_exit(struct completion
*comp
, long code
)
840 EXPORT_SYMBOL(complete_and_exit
);
842 SYSCALL_DEFINE1(exit
, int, error_code
)
844 do_exit((error_code
&0xff)<<8);
848 * Take down every thread in the group. This is called by fatal signals
849 * as well as by sys_exit_group (below).
852 do_group_exit(int exit_code
)
854 struct signal_struct
*sig
= current
->signal
;
856 BUG_ON(exit_code
& 0x80); /* core dumps don't get here */
858 if (signal_group_exit(sig
))
859 exit_code
= sig
->group_exit_code
;
860 else if (!thread_group_empty(current
)) {
861 struct sighand_struct
*const sighand
= current
->sighand
;
863 spin_lock_irq(&sighand
->siglock
);
864 if (signal_group_exit(sig
))
865 /* Another thread got here before we took the lock. */
866 exit_code
= sig
->group_exit_code
;
868 sig
->group_exit_code
= exit_code
;
869 sig
->flags
= SIGNAL_GROUP_EXIT
;
870 zap_other_threads(current
);
872 spin_unlock_irq(&sighand
->siglock
);
880 * this kills every thread in the thread group. Note that any externally
881 * wait4()-ing process will get the correct exit code - even if this
882 * thread is not the thread group leader.
884 SYSCALL_DEFINE1(exit_group
, int, error_code
)
886 do_group_exit((error_code
& 0xff) << 8);
892 enum pid_type wo_type
;
896 struct siginfo __user
*wo_info
;
898 struct rusage __user
*wo_rusage
;
900 wait_queue_t child_wait
;
905 struct pid
*task_pid_type(struct task_struct
*task
, enum pid_type type
)
907 if (type
!= PIDTYPE_PID
)
908 task
= task
->group_leader
;
909 return task
->pids
[type
].pid
;
912 static int eligible_pid(struct wait_opts
*wo
, struct task_struct
*p
)
914 return wo
->wo_type
== PIDTYPE_MAX
||
915 task_pid_type(p
, wo
->wo_type
) == wo
->wo_pid
;
918 static int eligible_child(struct wait_opts
*wo
, struct task_struct
*p
)
920 if (!eligible_pid(wo
, p
))
922 /* Wait for all children (clone and not) if __WALL is set;
923 * otherwise, wait for clone children *only* if __WCLONE is
924 * set; otherwise, wait for non-clone children *only*. (Note:
925 * A "clone" child here is one that reports to its parent
926 * using a signal other than SIGCHLD.) */
927 if (((p
->exit_signal
!= SIGCHLD
) ^ !!(wo
->wo_flags
& __WCLONE
))
928 && !(wo
->wo_flags
& __WALL
))
934 static int wait_noreap_copyout(struct wait_opts
*wo
, struct task_struct
*p
,
935 pid_t pid
, uid_t uid
, int why
, int status
)
937 struct siginfo __user
*infop
;
938 int retval
= wo
->wo_rusage
939 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
945 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
947 retval
= put_user(0, &infop
->si_errno
);
949 retval
= put_user((short)why
, &infop
->si_code
);
951 retval
= put_user(pid
, &infop
->si_pid
);
953 retval
= put_user(uid
, &infop
->si_uid
);
955 retval
= put_user(status
, &infop
->si_status
);
963 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
964 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
965 * the lock and this task is uninteresting. If we return nonzero, we have
966 * released the lock and the system call should return.
968 static int wait_task_zombie(struct wait_opts
*wo
, struct task_struct
*p
)
970 int state
, retval
, status
;
971 pid_t pid
= task_pid_vnr(p
);
972 uid_t uid
= from_kuid_munged(current_user_ns(), task_uid(p
));
973 struct siginfo __user
*infop
;
975 if (!likely(wo
->wo_flags
& WEXITED
))
978 if (unlikely(wo
->wo_flags
& WNOWAIT
)) {
979 int exit_code
= p
->exit_code
;
983 read_unlock(&tasklist_lock
);
984 sched_annotate_sleep();
986 if ((exit_code
& 0x7f) == 0) {
988 status
= exit_code
>> 8;
990 why
= (exit_code
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
991 status
= exit_code
& 0x7f;
993 return wait_noreap_copyout(wo
, p
, pid
, uid
, why
, status
);
996 * Move the task's state to DEAD/TRACE, only one thread can do this.
998 state
= (ptrace_reparented(p
) && thread_group_leader(p
)) ?
999 EXIT_TRACE
: EXIT_DEAD
;
1000 if (cmpxchg(&p
->exit_state
, EXIT_ZOMBIE
, state
) != EXIT_ZOMBIE
)
1003 * We own this thread, nobody else can reap it.
1005 read_unlock(&tasklist_lock
);
1006 sched_annotate_sleep();
1009 * Check thread_group_leader() to exclude the traced sub-threads.
1011 if (state
== EXIT_DEAD
&& thread_group_leader(p
)) {
1012 struct signal_struct
*sig
= p
->signal
;
1013 struct signal_struct
*psig
= current
->signal
;
1014 unsigned long maxrss
;
1015 cputime_t tgutime
, tgstime
;
1018 * The resource counters for the group leader are in its
1019 * own task_struct. Those for dead threads in the group
1020 * are in its signal_struct, as are those for the child
1021 * processes it has previously reaped. All these
1022 * accumulate in the parent's signal_struct c* fields.
1024 * We don't bother to take a lock here to protect these
1025 * p->signal fields because the whole thread group is dead
1026 * and nobody can change them.
1028 * psig->stats_lock also protects us from our sub-theads
1029 * which can reap other children at the same time. Until
1030 * we change k_getrusage()-like users to rely on this lock
1031 * we have to take ->siglock as well.
1033 * We use thread_group_cputime_adjusted() to get times for
1034 * the thread group, which consolidates times for all threads
1035 * in the group including the group leader.
1037 thread_group_cputime_adjusted(p
, &tgutime
, &tgstime
);
1038 spin_lock_irq(¤t
->sighand
->siglock
);
1039 write_seqlock(&psig
->stats_lock
);
1040 psig
->cutime
+= tgutime
+ sig
->cutime
;
1041 psig
->cstime
+= tgstime
+ sig
->cstime
;
1042 psig
->cgtime
+= task_gtime(p
) + sig
->gtime
+ sig
->cgtime
;
1044 p
->min_flt
+ sig
->min_flt
+ sig
->cmin_flt
;
1046 p
->maj_flt
+ sig
->maj_flt
+ sig
->cmaj_flt
;
1048 p
->nvcsw
+ sig
->nvcsw
+ sig
->cnvcsw
;
1050 p
->nivcsw
+ sig
->nivcsw
+ sig
->cnivcsw
;
1052 task_io_get_inblock(p
) +
1053 sig
->inblock
+ sig
->cinblock
;
1055 task_io_get_oublock(p
) +
1056 sig
->oublock
+ sig
->coublock
;
1057 maxrss
= max(sig
->maxrss
, sig
->cmaxrss
);
1058 if (psig
->cmaxrss
< maxrss
)
1059 psig
->cmaxrss
= maxrss
;
1060 task_io_accounting_add(&psig
->ioac
, &p
->ioac
);
1061 task_io_accounting_add(&psig
->ioac
, &sig
->ioac
);
1062 write_sequnlock(&psig
->stats_lock
);
1063 spin_unlock_irq(¤t
->sighand
->siglock
);
1066 retval
= wo
->wo_rusage
1067 ? getrusage(p
, RUSAGE_BOTH
, wo
->wo_rusage
) : 0;
1068 status
= (p
->signal
->flags
& SIGNAL_GROUP_EXIT
)
1069 ? p
->signal
->group_exit_code
: p
->exit_code
;
1070 if (!retval
&& wo
->wo_stat
)
1071 retval
= put_user(status
, wo
->wo_stat
);
1073 infop
= wo
->wo_info
;
1074 if (!retval
&& infop
)
1075 retval
= put_user(SIGCHLD
, &infop
->si_signo
);
1076 if (!retval
&& infop
)
1077 retval
= put_user(0, &infop
->si_errno
);
1078 if (!retval
&& infop
) {
1081 if ((status
& 0x7f) == 0) {
1085 why
= (status
& 0x80) ? CLD_DUMPED
: CLD_KILLED
;
1088 retval
= put_user((short)why
, &infop
->si_code
);
1090 retval
= put_user(status
, &infop
->si_status
);
1092 if (!retval
&& infop
)
1093 retval
= put_user(pid
, &infop
->si_pid
);
1094 if (!retval
&& infop
)
1095 retval
= put_user(uid
, &infop
->si_uid
);
1099 if (state
== EXIT_TRACE
) {
1100 write_lock_irq(&tasklist_lock
);
1101 /* We dropped tasklist, ptracer could die and untrace */
1104 /* If parent wants a zombie, don't release it now */
1105 state
= EXIT_ZOMBIE
;
1106 if (do_notify_parent(p
, p
->exit_signal
))
1108 p
->exit_state
= state
;
1109 write_unlock_irq(&tasklist_lock
);
1111 if (state
== EXIT_DEAD
)
1117 static int *task_stopped_code(struct task_struct
*p
, bool ptrace
)
1120 if (task_is_stopped_or_traced(p
) &&
1121 !(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 critiera 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
);