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/mnt_namespace.h>
16 #include <linux/iocontext.h>
17 #include <linux/key.h>
18 #include <linux/security.h>
19 #include <linux/cpu.h>
20 #include <linux/acct.h>
21 #include <linux/tsacct_kern.h>
22 #include <linux/file.h>
23 #include <linux/fdtable.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/freezer.h>
36 #include <linux/cgroup.h>
37 #include <linux/syscalls.h>
38 #include <linux/signal.h>
39 #include <linux/posix-timers.h>
40 #include <linux/cn_proc.h>
41 #include <linux/mutex.h>
42 #include <linux/futex.h>
43 #include <linux/pipe_fs_i.h>
44 #include <linux/audit.h> /* for audit_free() */
45 #include <linux/resource.h>
46 #include <linux/blkdev.h>
47 #include <linux/task_io_accounting_ops.h>
48 #include <linux/tracehook.h>
49 #include <linux/fs_struct.h>
50 #include <linux/init_task.h>
51 #include <trace/sched.h>
53 #include <asm/uaccess.h>
54 #include <asm/unistd.h>
55 #include <asm/pgtable.h>
56 #include <asm/mmu_context.h>
57 #include "cred-internals.h"
59 DEFINE_TRACE(sched_process_free);
60 DEFINE_TRACE(sched_process_exit);
61 DEFINE_TRACE(sched_process_wait);
63 static void exit_mm(struct task_struct * tsk);
65 static void __unhash_process(struct task_struct *p)
68 detach_pid(p, PIDTYPE_PID);
69 if (thread_group_leader(p)) {
70 detach_pid(p, PIDTYPE_PGID);
71 detach_pid(p, PIDTYPE_SID);
73 list_del_rcu(&p->tasks);
74 __get_cpu_var(process_counts)--;
76 list_del_rcu(&p->thread_group);
77 list_del_init(&p->sibling);
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 struct sighand_struct *sighand;
89 BUG_ON(!atomic_read(&sig->count));
91 sighand = rcu_dereference(tsk->sighand);
92 spin_lock(&sighand->siglock);
94 posix_cpu_timers_exit(tsk);
95 if (atomic_dec_and_test(&sig->count))
96 posix_cpu_timers_exit_group(tsk);
99 * If there is any task waiting for the group exit
102 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count)
103 wake_up_process(sig->group_exit_task);
105 if (tsk == sig->curr_target)
106 sig->curr_target = next_thread(tsk);
108 * Accumulate here the counters for all threads but the
109 * group leader as they die, so they can be added into
110 * the process-wide totals when those are taken.
111 * The group leader stays around as a zombie as long
112 * as there are other threads. When it gets reaped,
113 * the exit.c code will add its counts into these totals.
114 * We won't ever get here for the group leader, since it
115 * will have been the last reference on the signal_struct.
117 sig->utime = cputime_add(sig->utime, task_utime(tsk));
118 sig->stime = cputime_add(sig->stime, task_stime(tsk));
119 sig->gtime = cputime_add(sig->gtime, task_gtime(tsk));
120 sig->min_flt += tsk->min_flt;
121 sig->maj_flt += tsk->maj_flt;
122 sig->nvcsw += tsk->nvcsw;
123 sig->nivcsw += tsk->nivcsw;
124 sig->inblock += task_io_get_inblock(tsk);
125 sig->oublock += task_io_get_oublock(tsk);
126 task_io_accounting_add(&sig->ioac, &tsk->ioac);
127 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
128 sig = NULL; /* Marker for below. */
131 __unhash_process(tsk);
134 * Do this under ->siglock, we can race with another thread
135 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
137 flush_sigqueue(&tsk->pending);
141 spin_unlock(&sighand->siglock);
143 __cleanup_sighand(sighand);
144 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
146 flush_sigqueue(&sig->shared_pending);
147 taskstats_tgid_free(sig);
149 * Make sure ->signal can't go away under rq->lock,
150 * see account_group_exec_runtime().
152 task_rq_unlock_wait(tsk);
153 __cleanup_signal(sig);
157 static void delayed_put_task_struct(struct rcu_head *rhp)
159 struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);
161 trace_sched_process_free(tsk);
162 put_task_struct(tsk);
166 void release_task(struct task_struct * p)
168 struct task_struct *leader;
171 tracehook_prepare_release_task(p);
172 /* don't need to get the RCU readlock here - the process is dead and
173 * can't be modifying its own credentials */
174 atomic_dec(&__task_cred(p)->user->processes);
177 write_lock_irq(&tasklist_lock);
178 tracehook_finish_release_task(p);
182 * If we are the last non-leader member of the thread
183 * group, and the leader is zombie, then notify the
184 * group leader's parent process. (if it wants notification.)
187 leader = p->group_leader;
188 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
189 BUG_ON(task_detached(leader));
190 do_notify_parent(leader, leader->exit_signal);
192 * If we were the last child thread and the leader has
193 * exited already, and the leader's parent ignores SIGCHLD,
194 * then we are the one who should release the leader.
196 * do_notify_parent() will have marked it self-reaping in
199 zap_leader = task_detached(leader);
202 * This maintains the invariant that release_task()
203 * only runs on a task in EXIT_DEAD, just for sanity.
206 leader->exit_state = EXIT_DEAD;
209 write_unlock_irq(&tasklist_lock);
211 call_rcu(&p->rcu, delayed_put_task_struct);
214 if (unlikely(zap_leader))
219 * This checks not only the pgrp, but falls back on the pid if no
220 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
223 * The caller must hold rcu lock or the tasklist lock.
225 struct pid *session_of_pgrp(struct pid *pgrp)
227 struct task_struct *p;
228 struct pid *sid = NULL;
230 p = pid_task(pgrp, PIDTYPE_PGID);
232 p = pid_task(pgrp, PIDTYPE_PID);
234 sid = task_session(p);
240 * Determine if a process group is "orphaned", according to the POSIX
241 * definition in 2.2.2.52. Orphaned process groups are not to be affected
242 * by terminal-generated stop signals. Newly orphaned process groups are
243 * to receive a SIGHUP and a SIGCONT.
245 * "I ask you, have you ever known what it is to be an orphan?"
247 static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
249 struct task_struct *p;
251 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
252 if ((p == ignored_task) ||
253 (p->exit_state && thread_group_empty(p)) ||
254 is_global_init(p->real_parent))
257 if (task_pgrp(p->real_parent) != pgrp &&
258 task_session(p->real_parent) == task_session(p))
260 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
265 int is_current_pgrp_orphaned(void)
269 read_lock(&tasklist_lock);
270 retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
271 read_unlock(&tasklist_lock);
276 static int has_stopped_jobs(struct pid *pgrp)
279 struct task_struct *p;
281 do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
282 if (!task_is_stopped(p))
286 } while_each_pid_task(pgrp, PIDTYPE_PGID, p);
291 * Check to see if any process groups have become orphaned as
292 * a result of our exiting, and if they have any stopped jobs,
293 * send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
296 kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
298 struct pid *pgrp = task_pgrp(tsk);
299 struct task_struct *ignored_task = tsk;
302 /* exit: our father is in a different pgrp than
303 * we are and we were the only connection outside.
305 parent = tsk->real_parent;
307 /* reparent: our child is in a different pgrp than
308 * we are, and it was the only connection outside.
312 if (task_pgrp(parent) != pgrp &&
313 task_session(parent) == task_session(tsk) &&
314 will_become_orphaned_pgrp(pgrp, ignored_task) &&
315 has_stopped_jobs(pgrp)) {
316 __kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
317 __kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
322 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
324 * If a kernel thread is launched as a result of a system call, or if
325 * it ever exits, it should generally reparent itself to kthreadd so it
326 * isn't in the way of other processes and is correctly cleaned up on exit.
328 * The various task state such as scheduling policy and priority may have
329 * been inherited from a user process, so we reset them to sane values here.
331 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
333 static void reparent_to_kthreadd(void)
335 write_lock_irq(&tasklist_lock);
337 ptrace_unlink(current);
338 /* Reparent to init */
339 current->real_parent = current->parent = kthreadd_task;
340 list_move_tail(¤t->sibling, ¤t->real_parent->children);
342 /* Set the exit signal to SIGCHLD so we signal init on exit */
343 current->exit_signal = SIGCHLD;
345 if (task_nice(current) < 0)
346 set_user_nice(current, 0);
350 memcpy(current->signal->rlim, init_task.signal->rlim,
351 sizeof(current->signal->rlim));
353 atomic_inc(&init_cred.usage);
354 commit_creds(&init_cred);
355 write_unlock_irq(&tasklist_lock);
358 void __set_special_pids(struct pid *pid)
360 struct task_struct *curr = current->group_leader;
362 if (task_session(curr) != pid)
363 change_pid(curr, PIDTYPE_SID, pid);
365 if (task_pgrp(curr) != pid)
366 change_pid(curr, PIDTYPE_PGID, pid);
369 static void set_special_pids(struct pid *pid)
371 write_lock_irq(&tasklist_lock);
372 __set_special_pids(pid);
373 write_unlock_irq(&tasklist_lock);
377 * Let kernel threads use this to say that they
378 * allow a certain signal (since daemonize() will
379 * have disabled all of them by default).
381 int allow_signal(int sig)
383 if (!valid_signal(sig) || sig < 1)
386 spin_lock_irq(¤t->sighand->siglock);
387 sigdelset(¤t->blocked, sig);
389 /* Kernel threads handle their own signals.
390 Let the signal code know it'll be handled, so
391 that they don't get converted to SIGKILL or
392 just silently dropped */
393 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
396 spin_unlock_irq(¤t->sighand->siglock);
400 EXPORT_SYMBOL(allow_signal);
402 int disallow_signal(int sig)
404 if (!valid_signal(sig) || sig < 1)
407 spin_lock_irq(¤t->sighand->siglock);
408 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
410 spin_unlock_irq(¤t->sighand->siglock);
414 EXPORT_SYMBOL(disallow_signal);
417 * Put all the gunge required to become a kernel thread without
418 * attached user resources in one place where it belongs.
421 void daemonize(const char *name, ...)
426 va_start(args, name);
427 vsnprintf(current->comm, sizeof(current->comm), name, args);
431 * If we were started as result of loading a module, close all of the
432 * user space pages. We don't need them, and if we didn't close them
433 * they would be locked into memory.
437 * We don't want to have TIF_FREEZE set if the system-wide hibernation
438 * or suspend transition begins right now.
440 current->flags |= (PF_NOFREEZE | PF_KTHREAD);
442 if (current->nsproxy != &init_nsproxy) {
443 get_nsproxy(&init_nsproxy);
444 switch_task_namespaces(current, &init_nsproxy);
446 set_special_pids(&init_struct_pid);
447 proc_clear_tty(current);
449 /* Block and flush all signals */
450 sigfillset(&blocked);
451 sigprocmask(SIG_BLOCK, &blocked, NULL);
452 flush_signals(current);
454 /* Become as one with the init task */
456 daemonize_fs_struct();
458 current->files = init_task.files;
459 atomic_inc(¤t->files->count);
461 reparent_to_kthreadd();
464 EXPORT_SYMBOL(daemonize);
466 static void close_files(struct files_struct * files)
474 * It is safe to dereference the fd table without RCU or
475 * ->file_lock because this is the last reference to the
478 fdt = files_fdtable(files);
482 if (i >= fdt->max_fds)
484 set = fdt->open_fds->fds_bits[j++];
487 struct file * file = xchg(&fdt->fd[i], NULL);
489 filp_close(file, files);
499 struct files_struct *get_files_struct(struct task_struct *task)
501 struct files_struct *files;
506 atomic_inc(&files->count);
512 void put_files_struct(struct files_struct *files)
516 if (atomic_dec_and_test(&files->count)) {
519 * Free the fd and fdset arrays if we expanded them.
520 * If the fdtable was embedded, pass files for freeing
521 * at the end of the RCU grace period. Otherwise,
522 * you can free files immediately.
524 fdt = files_fdtable(files);
525 if (fdt != &files->fdtab)
526 kmem_cache_free(files_cachep, files);
531 void reset_files_struct(struct files_struct *files)
533 struct task_struct *tsk = current;
534 struct files_struct *old;
540 put_files_struct(old);
543 void exit_files(struct task_struct *tsk)
545 struct files_struct * files = tsk->files;
551 put_files_struct(files);
555 #ifdef CONFIG_MM_OWNER
557 * Task p is exiting and it owned mm, lets find a new owner for it
560 mm_need_new_owner(struct mm_struct *mm, struct task_struct *p)
563 * If there are other users of the mm and the owner (us) is exiting
564 * we need to find a new owner to take on the responsibility.
566 if (atomic_read(&mm->mm_users) <= 1)
573 void mm_update_next_owner(struct mm_struct *mm)
575 struct task_struct *c, *g, *p = current;
578 if (!mm_need_new_owner(mm, p))
581 read_lock(&tasklist_lock);
583 * Search in the children
585 list_for_each_entry(c, &p->children, sibling) {
587 goto assign_new_owner;
591 * Search in the siblings
593 list_for_each_entry(c, &p->parent->children, sibling) {
595 goto assign_new_owner;
599 * Search through everything else. We should not get
602 do_each_thread(g, c) {
604 goto assign_new_owner;
605 } while_each_thread(g, c);
607 read_unlock(&tasklist_lock);
609 * We found no owner yet mm_users > 1: this implies that we are
610 * most likely racing with swapoff (try_to_unuse()) or /proc or
611 * ptrace or page migration (get_task_mm()). Mark owner as NULL.
620 * The task_lock protects c->mm from changing.
621 * We always want mm->owner->mm == mm
625 * Delay read_unlock() till we have the task_lock()
626 * to ensure that c does not slip away underneath us
628 read_unlock(&tasklist_lock);
638 #endif /* CONFIG_MM_OWNER */
641 * Turn us into a lazy TLB process if we
644 static void exit_mm(struct task_struct * tsk)
646 struct mm_struct *mm = tsk->mm;
647 struct core_state *core_state;
653 * Serialize with any possible pending coredump.
654 * We must hold mmap_sem around checking core_state
655 * and clearing tsk->mm. The core-inducing thread
656 * will increment ->nr_threads for each thread in the
657 * group with ->mm != NULL.
659 down_read(&mm->mmap_sem);
660 core_state = mm->core_state;
662 struct core_thread self;
663 up_read(&mm->mmap_sem);
666 self.next = xchg(&core_state->dumper.next, &self);
668 * Implies mb(), the result of xchg() must be visible
669 * to core_state->dumper.
671 if (atomic_dec_and_test(&core_state->nr_threads))
672 complete(&core_state->startup);
675 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
676 if (!self.task) /* see coredump_finish() */
680 __set_task_state(tsk, TASK_RUNNING);
681 down_read(&mm->mmap_sem);
683 atomic_inc(&mm->mm_count);
684 BUG_ON(mm != tsk->active_mm);
685 /* more a memory barrier than a real lock */
688 up_read(&mm->mmap_sem);
689 enter_lazy_tlb(mm, current);
690 /* We don't want this task to be frozen prematurely */
691 clear_freeze_flag(tsk);
693 mm_update_next_owner(mm);
698 * When we die, we re-parent all our children.
699 * Try to give them to another thread in our thread
700 * group, and if no such member exists, give it to
701 * the child reaper process (ie "init") in our pid
704 static struct task_struct *find_new_reaper(struct task_struct *father)
706 struct pid_namespace *pid_ns = task_active_pid_ns(father);
707 struct task_struct *thread;
710 while_each_thread(father, thread) {
711 if (thread->flags & PF_EXITING)
713 if (unlikely(pid_ns->child_reaper == father))
714 pid_ns->child_reaper = thread;
718 if (unlikely(pid_ns->child_reaper == father)) {
719 write_unlock_irq(&tasklist_lock);
720 if (unlikely(pid_ns == &init_pid_ns))
721 panic("Attempted to kill init!");
723 zap_pid_ns_processes(pid_ns);
724 write_lock_irq(&tasklist_lock);
726 * We can not clear ->child_reaper or leave it alone.
727 * There may by stealth EXIT_DEAD tasks on ->children,
728 * forget_original_parent() must move them somewhere.
730 pid_ns->child_reaper = init_pid_ns.child_reaper;
733 return pid_ns->child_reaper;
737 * Any that need to be release_task'd are put on the @dead list.
739 static void reparent_thread(struct task_struct *father, struct task_struct *p,
740 struct list_head *dead)
742 if (p->pdeath_signal)
743 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
745 list_move_tail(&p->sibling, &p->real_parent->children);
747 if (task_detached(p))
750 * If this is a threaded reparent there is no need to
751 * notify anyone anything has happened.
753 if (same_thread_group(p->real_parent, father))
756 /* We don't want people slaying init. */
757 p->exit_signal = SIGCHLD;
759 /* If it has exited notify the new parent about this child's death. */
761 p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
762 do_notify_parent(p, p->exit_signal);
763 if (task_detached(p)) {
764 p->exit_state = EXIT_DEAD;
765 list_move_tail(&p->sibling, dead);
769 kill_orphaned_pgrp(p, father);
772 static void forget_original_parent(struct task_struct *father)
774 struct task_struct *p, *n, *reaper;
775 LIST_HEAD(dead_children);
779 write_lock_irq(&tasklist_lock);
780 reaper = find_new_reaper(father);
782 list_for_each_entry_safe(p, n, &father->children, sibling) {
783 p->real_parent = reaper;
784 if (p->parent == father) {
786 p->parent = p->real_parent;
788 reparent_thread(father, p, &dead_children);
790 write_unlock_irq(&tasklist_lock);
792 BUG_ON(!list_empty(&father->children));
794 list_for_each_entry_safe(p, n, &dead_children, sibling) {
795 list_del_init(&p->sibling);
801 * Send signals to all our closest relatives so that they know
802 * to properly mourn us..
804 static void exit_notify(struct task_struct *tsk, int group_dead)
810 * This does two things:
812 * A. Make init inherit all the child processes
813 * B. Check to see if any process groups have become orphaned
814 * as a result of our exiting, and if they have any stopped
815 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
817 forget_original_parent(tsk);
818 exit_task_namespaces(tsk);
820 write_lock_irq(&tasklist_lock);
822 kill_orphaned_pgrp(tsk->group_leader, NULL);
824 /* Let father know we died
826 * Thread signals are configurable, but you aren't going to use
827 * that to send signals to arbitary processes.
828 * That stops right now.
830 * If the parent exec id doesn't match the exec id we saved
831 * when we started then we know the parent has changed security
834 * If our self_exec id doesn't match our parent_exec_id then
835 * we have changed execution domain as these two values started
836 * the same after a fork.
838 if (tsk->exit_signal != SIGCHLD && !task_detached(tsk) &&
839 (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
840 tsk->self_exec_id != tsk->parent_exec_id) &&
842 tsk->exit_signal = SIGCHLD;
844 signal = tracehook_notify_death(tsk, &cookie, group_dead);
846 signal = do_notify_parent(tsk, signal);
848 tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE;
850 /* mt-exec, de_thread() is waiting for us */
851 if (thread_group_leader(tsk) &&
852 tsk->signal->group_exit_task &&
853 tsk->signal->notify_count < 0)
854 wake_up_process(tsk->signal->group_exit_task);
856 write_unlock_irq(&tasklist_lock);
858 tracehook_report_death(tsk, signal, cookie, group_dead);
860 /* If the process is dead, release it - nobody will wait for it */
861 if (signal == DEATH_REAP)
865 #ifdef CONFIG_DEBUG_STACK_USAGE
866 static void check_stack_usage(void)
868 static DEFINE_SPINLOCK(low_water_lock);
869 static int lowest_to_date = THREAD_SIZE;
872 free = stack_not_used(current);
874 if (free >= lowest_to_date)
877 spin_lock(&low_water_lock);
878 if (free < lowest_to_date) {
879 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
881 current->comm, free);
882 lowest_to_date = free;
884 spin_unlock(&low_water_lock);
887 static inline void check_stack_usage(void) {}
890 NORET_TYPE void do_exit(long code)
892 struct task_struct *tsk = current;
895 profile_task_exit(tsk);
897 WARN_ON(atomic_read(&tsk->fs_excl));
899 if (unlikely(in_interrupt()))
900 panic("Aiee, killing interrupt handler!");
901 if (unlikely(!tsk->pid))
902 panic("Attempted to kill the idle task!");
904 tracehook_report_exit(&code);
907 * We're taking recursive faults here in do_exit. Safest is to just
908 * leave this task alone and wait for reboot.
910 if (unlikely(tsk->flags & PF_EXITING)) {
912 "Fixing recursive fault but reboot is needed!\n");
914 * We can do this unlocked here. The futex code uses
915 * this flag just to verify whether the pi state
916 * cleanup has been done or not. In the worst case it
917 * loops once more. We pretend that the cleanup was
918 * done as there is no way to return. Either the
919 * OWNER_DIED bit is set by now or we push the blocked
920 * task into the wait for ever nirwana as well.
922 tsk->flags |= PF_EXITPIDONE;
923 set_current_state(TASK_UNINTERRUPTIBLE);
929 exit_signals(tsk); /* sets PF_EXITING */
931 * tsk->flags are checked in the futex code to protect against
932 * an exiting task cleaning up the robust pi futexes.
935 spin_unlock_wait(&tsk->pi_lock);
937 if (unlikely(in_atomic()))
938 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
939 current->comm, task_pid_nr(current),
942 acct_update_integrals(tsk);
944 group_dead = atomic_dec_and_test(&tsk->signal->live);
946 hrtimer_cancel(&tsk->signal->real_timer);
947 exit_itimers(tsk->signal);
949 acct_collect(code, group_dead);
952 if (unlikely(tsk->audit_context))
955 tsk->exit_code = code;
956 taskstats_exit(tsk, group_dead);
962 trace_sched_process_exit(tsk);
971 if (group_dead && tsk->signal->leader)
972 disassociate_ctty(1);
974 module_put(task_thread_info(tsk)->exec_domain->module);
976 module_put(tsk->binfmt->module);
978 proc_exit_connector(tsk);
979 exit_notify(tsk, group_dead);
981 mpol_put(tsk->mempolicy);
982 tsk->mempolicy = NULL;
986 * This must happen late, after the PID is not
989 if (unlikely(!list_empty(&tsk->pi_state_list)))
990 exit_pi_state_list(tsk);
991 if (unlikely(current->pi_state_cache))
992 kfree(current->pi_state_cache);
995 * Make sure we are holding no locks:
997 debug_check_no_locks_held(tsk);
999 * We can do this unlocked here. The futex code uses this flag
1000 * just to verify whether the pi state cleanup has been done
1001 * or not. In the worst case it loops once more.
1003 tsk->flags |= PF_EXITPIDONE;
1005 if (tsk->io_context)
1008 if (tsk->splice_pipe)
1009 __free_pipe_info(tsk->splice_pipe);
1012 /* causes final put_task_struct in finish_task_switch(). */
1013 tsk->state = TASK_DEAD;
1016 /* Avoid "noreturn function does return". */
1018 cpu_relax(); /* For when BUG is null */
1021 EXPORT_SYMBOL_GPL(do_exit);
1023 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
1031 EXPORT_SYMBOL(complete_and_exit);
1033 SYSCALL_DEFINE1(exit, int, error_code)
1035 do_exit((error_code&0xff)<<8);
1039 * Take down every thread in the group. This is called by fatal signals
1040 * as well as by sys_exit_group (below).
1043 do_group_exit(int exit_code)
1045 struct signal_struct *sig = current->signal;
1047 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1049 if (signal_group_exit(sig))
1050 exit_code = sig->group_exit_code;
1051 else if (!thread_group_empty(current)) {
1052 struct sighand_struct *const sighand = current->sighand;
1053 spin_lock_irq(&sighand->siglock);
1054 if (signal_group_exit(sig))
1055 /* Another thread got here before we took the lock. */
1056 exit_code = sig->group_exit_code;
1058 sig->group_exit_code = exit_code;
1059 sig->flags = SIGNAL_GROUP_EXIT;
1060 zap_other_threads(current);
1062 spin_unlock_irq(&sighand->siglock);
1070 * this kills every thread in the thread group. Note that any externally
1071 * wait4()-ing process will get the correct exit code - even if this
1072 * thread is not the thread group leader.
1074 SYSCALL_DEFINE1(exit_group, int, error_code)
1076 do_group_exit((error_code & 0xff) << 8);
1081 static struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
1083 struct pid *pid = NULL;
1084 if (type == PIDTYPE_PID)
1085 pid = task->pids[type].pid;
1086 else if (type < PIDTYPE_MAX)
1087 pid = task->group_leader->pids[type].pid;
1091 static int eligible_child(enum pid_type type, struct pid *pid, int options,
1092 struct task_struct *p)
1096 if (type < PIDTYPE_MAX) {
1097 if (task_pid_type(p, type) != pid)
1101 /* Wait for all children (clone and not) if __WALL is set;
1102 * otherwise, wait for clone children *only* if __WCLONE is
1103 * set; otherwise, wait for non-clone children *only*. (Note:
1104 * A "clone" child here is one that reports to its parent
1105 * using a signal other than SIGCHLD.) */
1106 if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1107 && !(options & __WALL))
1110 err = security_task_wait(p);
1117 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1118 int why, int status,
1119 struct siginfo __user *infop,
1120 struct rusage __user *rusagep)
1122 int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1126 retval = put_user(SIGCHLD, &infop->si_signo);
1128 retval = put_user(0, &infop->si_errno);
1130 retval = put_user((short)why, &infop->si_code);
1132 retval = put_user(pid, &infop->si_pid);
1134 retval = put_user(uid, &infop->si_uid);
1136 retval = put_user(status, &infop->si_status);
1143 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1144 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1145 * the lock and this task is uninteresting. If we return nonzero, we have
1146 * released the lock and the system call should return.
1148 static int wait_task_zombie(struct task_struct *p, int options,
1149 struct siginfo __user *infop,
1150 int __user *stat_addr, struct rusage __user *ru)
1152 unsigned long state;
1153 int retval, status, traced;
1154 pid_t pid = task_pid_vnr(p);
1155 uid_t uid = __task_cred(p)->uid;
1157 if (!likely(options & WEXITED))
1160 if (unlikely(options & WNOWAIT)) {
1161 int exit_code = p->exit_code;
1165 read_unlock(&tasklist_lock);
1166 if ((exit_code & 0x7f) == 0) {
1168 status = exit_code >> 8;
1170 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1171 status = exit_code & 0x7f;
1173 return wait_noreap_copyout(p, pid, uid, why,
1178 * Try to move the task's state to DEAD
1179 * only one thread is allowed to do this:
1181 state = xchg(&p->exit_state, EXIT_DEAD);
1182 if (state != EXIT_ZOMBIE) {
1183 BUG_ON(state != EXIT_DEAD);
1187 traced = ptrace_reparented(p);
1189 if (likely(!traced)) {
1190 struct signal_struct *psig;
1191 struct signal_struct *sig;
1192 struct task_cputime cputime;
1195 * The resource counters for the group leader are in its
1196 * own task_struct. Those for dead threads in the group
1197 * are in its signal_struct, as are those for the child
1198 * processes it has previously reaped. All these
1199 * accumulate in the parent's signal_struct c* fields.
1201 * We don't bother to take a lock here to protect these
1202 * p->signal fields, because they are only touched by
1203 * __exit_signal, which runs with tasklist_lock
1204 * write-locked anyway, and so is excluded here. We do
1205 * need to protect the access to p->parent->signal fields,
1206 * as other threads in the parent group can be right
1207 * here reaping other children at the same time.
1209 * We use thread_group_cputime() to get times for the thread
1210 * group, which consolidates times for all threads in the
1211 * group including the group leader.
1213 thread_group_cputime(p, &cputime);
1214 spin_lock_irq(&p->parent->sighand->siglock);
1215 psig = p->parent->signal;
1218 cputime_add(psig->cutime,
1219 cputime_add(cputime.utime,
1222 cputime_add(psig->cstime,
1223 cputime_add(cputime.stime,
1226 cputime_add(psig->cgtime,
1227 cputime_add(p->gtime,
1228 cputime_add(sig->gtime,
1231 p->min_flt + sig->min_flt + sig->cmin_flt;
1233 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1235 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1237 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1239 task_io_get_inblock(p) +
1240 sig->inblock + sig->cinblock;
1242 task_io_get_oublock(p) +
1243 sig->oublock + sig->coublock;
1244 task_io_accounting_add(&psig->ioac, &p->ioac);
1245 task_io_accounting_add(&psig->ioac, &sig->ioac);
1246 spin_unlock_irq(&p->parent->sighand->siglock);
1250 * Now we are sure this task is interesting, and no other
1251 * thread can reap it because we set its state to EXIT_DEAD.
1253 read_unlock(&tasklist_lock);
1255 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1256 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1257 ? p->signal->group_exit_code : p->exit_code;
1258 if (!retval && stat_addr)
1259 retval = put_user(status, stat_addr);
1260 if (!retval && infop)
1261 retval = put_user(SIGCHLD, &infop->si_signo);
1262 if (!retval && infop)
1263 retval = put_user(0, &infop->si_errno);
1264 if (!retval && infop) {
1267 if ((status & 0x7f) == 0) {
1271 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1274 retval = put_user((short)why, &infop->si_code);
1276 retval = put_user(status, &infop->si_status);
1278 if (!retval && infop)
1279 retval = put_user(pid, &infop->si_pid);
1280 if (!retval && infop)
1281 retval = put_user(uid, &infop->si_uid);
1286 write_lock_irq(&tasklist_lock);
1287 /* We dropped tasklist, ptracer could die and untrace */
1290 * If this is not a detached task, notify the parent.
1291 * If it's still not detached after that, don't release
1294 if (!task_detached(p)) {
1295 do_notify_parent(p, p->exit_signal);
1296 if (!task_detached(p)) {
1297 p->exit_state = EXIT_ZOMBIE;
1301 write_unlock_irq(&tasklist_lock);
1309 static int *task_stopped_code(struct task_struct *p, bool ptrace)
1312 if (task_is_stopped_or_traced(p))
1313 return &p->exit_code;
1315 if (p->signal->flags & SIGNAL_STOP_STOPPED)
1316 return &p->signal->group_exit_code;
1322 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1323 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1324 * the lock and this task is uninteresting. If we return nonzero, we have
1325 * released the lock and the system call should return.
1327 static int wait_task_stopped(int ptrace, struct task_struct *p,
1328 int options, struct siginfo __user *infop,
1329 int __user *stat_addr, struct rusage __user *ru)
1331 int retval, exit_code, *p_code, why;
1332 uid_t uid = 0; /* unneeded, required by compiler */
1335 if (!(options & WUNTRACED))
1339 spin_lock_irq(&p->sighand->siglock);
1341 p_code = task_stopped_code(p, ptrace);
1342 if (unlikely(!p_code))
1345 exit_code = *p_code;
1349 if (!unlikely(options & WNOWAIT))
1352 /* don't need the RCU readlock here as we're holding a spinlock */
1353 uid = __task_cred(p)->uid;
1355 spin_unlock_irq(&p->sighand->siglock);
1360 * Now we are pretty sure this task is interesting.
1361 * Make sure it doesn't get reaped out from under us while we
1362 * give up the lock and then examine it below. We don't want to
1363 * keep holding onto the tasklist_lock while we call getrusage and
1364 * possibly take page faults for user memory.
1367 pid = task_pid_vnr(p);
1368 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1369 read_unlock(&tasklist_lock);
1371 if (unlikely(options & WNOWAIT))
1372 return wait_noreap_copyout(p, pid, uid,
1376 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1377 if (!retval && stat_addr)
1378 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1379 if (!retval && infop)
1380 retval = put_user(SIGCHLD, &infop->si_signo);
1381 if (!retval && infop)
1382 retval = put_user(0, &infop->si_errno);
1383 if (!retval && infop)
1384 retval = put_user((short)why, &infop->si_code);
1385 if (!retval && infop)
1386 retval = put_user(exit_code, &infop->si_status);
1387 if (!retval && infop)
1388 retval = put_user(pid, &infop->si_pid);
1389 if (!retval && infop)
1390 retval = put_user(uid, &infop->si_uid);
1400 * Handle do_wait work for one task in a live, non-stopped state.
1401 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1402 * the lock and this task is uninteresting. If we return nonzero, we have
1403 * released the lock and the system call should return.
1405 static int wait_task_continued(struct task_struct *p, int options,
1406 struct siginfo __user *infop,
1407 int __user *stat_addr, struct rusage __user *ru)
1413 if (!unlikely(options & WCONTINUED))
1416 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1419 spin_lock_irq(&p->sighand->siglock);
1420 /* Re-check with the lock held. */
1421 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1422 spin_unlock_irq(&p->sighand->siglock);
1425 if (!unlikely(options & WNOWAIT))
1426 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1427 uid = __task_cred(p)->uid;
1428 spin_unlock_irq(&p->sighand->siglock);
1430 pid = task_pid_vnr(p);
1432 read_unlock(&tasklist_lock);
1435 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1437 if (!retval && stat_addr)
1438 retval = put_user(0xffff, stat_addr);
1442 retval = wait_noreap_copyout(p, pid, uid,
1443 CLD_CONTINUED, SIGCONT,
1445 BUG_ON(retval == 0);
1452 * Consider @p for a wait by @parent.
1454 * -ECHILD should be in *@notask_error before the first call.
1455 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1456 * Returns zero if the search for a child should continue;
1457 * then *@notask_error is 0 if @p is an eligible child,
1458 * or another error from security_task_wait(), or still -ECHILD.
1460 static int wait_consider_task(struct task_struct *parent, int ptrace,
1461 struct task_struct *p, int *notask_error,
1462 enum pid_type type, struct pid *pid, int options,
1463 struct siginfo __user *infop,
1464 int __user *stat_addr, struct rusage __user *ru)
1466 int ret = eligible_child(type, pid, options, p);
1470 if (unlikely(ret < 0)) {
1472 * If we have not yet seen any eligible child,
1473 * then let this error code replace -ECHILD.
1474 * A permission error will give the user a clue
1475 * to look for security policy problems, rather
1476 * than for mysterious wait bugs.
1479 *notask_error = ret;
1482 if (likely(!ptrace) && unlikely(p->ptrace)) {
1484 * This child is hidden by ptrace.
1485 * We aren't allowed to see it now, but eventually we will.
1491 if (p->exit_state == EXIT_DEAD)
1495 * We don't reap group leaders with subthreads.
1497 if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p))
1498 return wait_task_zombie(p, options, infop, stat_addr, ru);
1501 * It's stopped or running now, so it might
1502 * later continue, exit, or stop again.
1506 if (task_stopped_code(p, ptrace))
1507 return wait_task_stopped(ptrace, p, options,
1508 infop, stat_addr, ru);
1510 return wait_task_continued(p, options, infop, stat_addr, ru);
1514 * Do the work of do_wait() for one thread in the group, @tsk.
1516 * -ECHILD should be in *@notask_error before the first call.
1517 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1518 * Returns zero if the search for a child should continue; then
1519 * *@notask_error is 0 if there were any eligible children,
1520 * or another error from security_task_wait(), or still -ECHILD.
1522 static int do_wait_thread(struct task_struct *tsk, int *notask_error,
1523 enum pid_type type, struct pid *pid, int options,
1524 struct siginfo __user *infop, int __user *stat_addr,
1525 struct rusage __user *ru)
1527 struct task_struct *p;
1529 list_for_each_entry(p, &tsk->children, sibling) {
1531 * Do not consider detached threads.
1533 if (!task_detached(p)) {
1534 int ret = wait_consider_task(tsk, 0, p, notask_error,
1536 infop, stat_addr, ru);
1545 static int ptrace_do_wait(struct task_struct *tsk, int *notask_error,
1546 enum pid_type type, struct pid *pid, int options,
1547 struct siginfo __user *infop, int __user *stat_addr,
1548 struct rusage __user *ru)
1550 struct task_struct *p;
1553 * Traditionally we see ptrace'd stopped tasks regardless of options.
1555 options |= WUNTRACED;
1557 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1558 int ret = wait_consider_task(tsk, 1, p, notask_error,
1560 infop, stat_addr, ru);
1568 static long do_wait(enum pid_type type, struct pid *pid, int options,
1569 struct siginfo __user *infop, int __user *stat_addr,
1570 struct rusage __user *ru)
1572 DECLARE_WAITQUEUE(wait, current);
1573 struct task_struct *tsk;
1576 trace_sched_process_wait(pid);
1578 add_wait_queue(¤t->signal->wait_chldexit,&wait);
1581 * If there is nothing that can match our critiera just get out.
1582 * We will clear @retval to zero if we see any child that might later
1583 * match our criteria, even if we are not able to reap it yet.
1586 if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type])))
1589 current->state = TASK_INTERRUPTIBLE;
1590 read_lock(&tasklist_lock);
1593 int tsk_result = do_wait_thread(tsk, &retval,
1595 infop, stat_addr, ru);
1597 tsk_result = ptrace_do_wait(tsk, &retval,
1599 infop, stat_addr, ru);
1602 * tasklist_lock is unlocked and we have a final result.
1604 retval = tsk_result;
1608 if (options & __WNOTHREAD)
1610 tsk = next_thread(tsk);
1611 BUG_ON(tsk->signal != current->signal);
1612 } while (tsk != current);
1613 read_unlock(&tasklist_lock);
1615 if (!retval && !(options & WNOHANG)) {
1616 retval = -ERESTARTSYS;
1617 if (!signal_pending(current)) {
1624 current->state = TASK_RUNNING;
1625 remove_wait_queue(¤t->signal->wait_chldexit,&wait);
1631 * For a WNOHANG return, clear out all the fields
1632 * we would set so the user can easily tell the
1636 retval = put_user(0, &infop->si_signo);
1638 retval = put_user(0, &infop->si_errno);
1640 retval = put_user(0, &infop->si_code);
1642 retval = put_user(0, &infop->si_pid);
1644 retval = put_user(0, &infop->si_uid);
1646 retval = put_user(0, &infop->si_status);
1652 SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
1653 infop, int, options, struct rusage __user *, ru)
1655 struct pid *pid = NULL;
1659 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1661 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1674 type = PIDTYPE_PGID;
1682 if (type < PIDTYPE_MAX)
1683 pid = find_get_pid(upid);
1684 ret = do_wait(type, pid, options, infop, NULL, ru);
1687 /* avoid REGPARM breakage on x86: */
1688 asmlinkage_protect(5, ret, which, upid, infop, options, ru);
1692 SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
1693 int, options, struct rusage __user *, ru)
1695 struct pid *pid = NULL;
1699 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1700 __WNOTHREAD|__WCLONE|__WALL))
1705 else if (upid < 0) {
1706 type = PIDTYPE_PGID;
1707 pid = find_get_pid(-upid);
1708 } else if (upid == 0) {
1709 type = PIDTYPE_PGID;
1710 pid = get_task_pid(current, PIDTYPE_PGID);
1711 } else /* upid > 0 */ {
1713 pid = find_get_pid(upid);
1716 ret = do_wait(type, pid, options | WEXITED, NULL, stat_addr, ru);
1719 /* avoid REGPARM breakage on x86: */
1720 asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
1724 #ifdef __ARCH_WANT_SYS_WAITPID
1727 * sys_waitpid() remains for compatibility. waitpid() should be
1728 * implemented by calling sys_wait4() from libc.a.
1730 SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
1732 return sys_wait4(pid, stat_addr, options, NULL);