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/compat.h>
44 #include <linux/pipe_fs_i.h>
45 #include <linux/audit.h> /* for audit_free() */
46 #include <linux/resource.h>
47 #include <linux/blkdev.h>
48 #include <linux/task_io_accounting_ops.h>
50 #include <asm/uaccess.h>
51 #include <asm/unistd.h>
52 #include <asm/pgtable.h>
53 #include <asm/mmu_context.h>
55 static void exit_mm(struct task_struct * tsk);
57 static inline int task_detached(struct task_struct *p)
59 return p->exit_signal == -1;
62 static void __unhash_process(struct task_struct *p)
65 detach_pid(p, PIDTYPE_PID);
66 if (thread_group_leader(p)) {
67 detach_pid(p, PIDTYPE_PGID);
68 detach_pid(p, PIDTYPE_SID);
70 list_del_rcu(&p->tasks);
71 __get_cpu_var(process_counts)--;
73 list_del_rcu(&p->thread_group);
74 list_del_init(&p->sibling);
78 * This function expects the tasklist_lock write-locked.
80 static void __exit_signal(struct task_struct *tsk)
82 struct signal_struct *sig = tsk->signal;
83 struct sighand_struct *sighand;
86 BUG_ON(!atomic_read(&sig->count));
88 sighand = rcu_dereference(tsk->sighand);
89 spin_lock(&sighand->siglock);
91 posix_cpu_timers_exit(tsk);
92 if (atomic_dec_and_test(&sig->count))
93 posix_cpu_timers_exit_group(tsk);
96 * If there is any task waiting for the group exit
99 if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count)
100 wake_up_process(sig->group_exit_task);
102 if (tsk == sig->curr_target)
103 sig->curr_target = next_thread(tsk);
105 * Accumulate here the counters for all threads but the
106 * group leader as they die, so they can be added into
107 * the process-wide totals when those are taken.
108 * The group leader stays around as a zombie as long
109 * as there are other threads. When it gets reaped,
110 * the exit.c code will add its counts into these totals.
111 * We won't ever get here for the group leader, since it
112 * will have been the last reference on the signal_struct.
114 sig->utime = cputime_add(sig->utime, tsk->utime);
115 sig->stime = cputime_add(sig->stime, tsk->stime);
116 sig->gtime = cputime_add(sig->gtime, tsk->gtime);
117 sig->min_flt += tsk->min_flt;
118 sig->maj_flt += tsk->maj_flt;
119 sig->nvcsw += tsk->nvcsw;
120 sig->nivcsw += tsk->nivcsw;
121 sig->inblock += task_io_get_inblock(tsk);
122 sig->oublock += task_io_get_oublock(tsk);
123 #ifdef CONFIG_TASK_XACCT
124 sig->rchar += tsk->rchar;
125 sig->wchar += tsk->wchar;
126 sig->syscr += tsk->syscr;
127 sig->syscw += tsk->syscw;
128 #endif /* CONFIG_TASK_XACCT */
129 #ifdef CONFIG_TASK_IO_ACCOUNTING
130 sig->ioac.read_bytes += tsk->ioac.read_bytes;
131 sig->ioac.write_bytes += tsk->ioac.write_bytes;
132 sig->ioac.cancelled_write_bytes +=
133 tsk->ioac.cancelled_write_bytes;
134 #endif /* CONFIG_TASK_IO_ACCOUNTING */
135 sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
136 sig = NULL; /* Marker for below. */
139 __unhash_process(tsk);
142 * Do this under ->siglock, we can race with another thread
143 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
145 flush_sigqueue(&tsk->pending);
149 spin_unlock(&sighand->siglock);
151 __cleanup_sighand(sighand);
152 clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
154 flush_sigqueue(&sig->shared_pending);
155 taskstats_tgid_free(sig);
156 __cleanup_signal(sig);
160 static void delayed_put_task_struct(struct rcu_head *rhp)
162 put_task_struct(container_of(rhp, struct task_struct, rcu));
166 * Do final ptrace-related cleanup of a zombie being reaped.
168 * Called with write_lock(&tasklist_lock) held.
170 static void ptrace_release_task(struct task_struct *p)
172 BUG_ON(!list_empty(&p->ptraced));
174 BUG_ON(!list_empty(&p->ptrace_entry));
177 void release_task(struct task_struct * p)
179 struct task_struct *leader;
182 atomic_dec(&p->user->processes);
184 write_lock_irq(&tasklist_lock);
185 ptrace_release_task(p);
189 * If we are the last non-leader member of the thread
190 * group, and the leader is zombie, then notify the
191 * group leader's parent process. (if it wants notification.)
194 leader = p->group_leader;
195 if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
196 BUG_ON(task_detached(leader));
197 do_notify_parent(leader, leader->exit_signal);
199 * If we were the last child thread and the leader has
200 * exited already, and the leader's parent ignores SIGCHLD,
201 * then we are the one who should release the leader.
203 * do_notify_parent() will have marked it self-reaping in
206 zap_leader = task_detached(leader);
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 security_task_reparent_to_init(current);
351 memcpy(current->signal->rlim, init_task.signal->rlim,
352 sizeof(current->signal->rlim));
353 atomic_inc(&(INIT_USER->__count));
354 write_unlock_irq(&tasklist_lock);
355 switch_uid(INIT_USER);
358 void __set_special_pids(struct pid *pid)
360 struct task_struct *curr = current->group_leader;
361 pid_t nr = pid_nr(pid);
363 if (task_session(curr) != pid) {
364 change_pid(curr, PIDTYPE_SID, pid);
365 set_task_session(curr, nr);
367 if (task_pgrp(curr) != pid) {
368 change_pid(curr, PIDTYPE_PGID, pid);
369 set_task_pgrp(curr, nr);
373 static void set_special_pids(struct pid *pid)
375 write_lock_irq(&tasklist_lock);
376 __set_special_pids(pid);
377 write_unlock_irq(&tasklist_lock);
381 * Let kernel threads use this to say that they
382 * allow a certain signal (since daemonize() will
383 * have disabled all of them by default).
385 int allow_signal(int sig)
387 if (!valid_signal(sig) || sig < 1)
390 spin_lock_irq(¤t->sighand->siglock);
391 sigdelset(¤t->blocked, sig);
393 /* Kernel threads handle their own signals.
394 Let the signal code know it'll be handled, so
395 that they don't get converted to SIGKILL or
396 just silently dropped */
397 current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
400 spin_unlock_irq(¤t->sighand->siglock);
404 EXPORT_SYMBOL(allow_signal);
406 int disallow_signal(int sig)
408 if (!valid_signal(sig) || sig < 1)
411 spin_lock_irq(¤t->sighand->siglock);
412 current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
414 spin_unlock_irq(¤t->sighand->siglock);
418 EXPORT_SYMBOL(disallow_signal);
421 * Put all the gunge required to become a kernel thread without
422 * attached user resources in one place where it belongs.
425 void daemonize(const char *name, ...)
428 struct fs_struct *fs;
431 va_start(args, name);
432 vsnprintf(current->comm, sizeof(current->comm), name, args);
436 * If we were started as result of loading a module, close all of the
437 * user space pages. We don't need them, and if we didn't close them
438 * they would be locked into memory.
442 * We don't want to have TIF_FREEZE set if the system-wide hibernation
443 * or suspend transition begins right now.
445 current->flags |= (PF_NOFREEZE | PF_KTHREAD);
447 if (current->nsproxy != &init_nsproxy) {
448 get_nsproxy(&init_nsproxy);
449 switch_task_namespaces(current, &init_nsproxy);
451 set_special_pids(&init_struct_pid);
452 proc_clear_tty(current);
454 /* Block and flush all signals */
455 sigfillset(&blocked);
456 sigprocmask(SIG_BLOCK, &blocked, NULL);
457 flush_signals(current);
459 /* Become as one with the init task */
461 exit_fs(current); /* current->fs->count--; */
464 atomic_inc(&fs->count);
467 current->files = init_task.files;
468 atomic_inc(¤t->files->count);
470 reparent_to_kthreadd();
473 EXPORT_SYMBOL(daemonize);
475 static void close_files(struct files_struct * files)
483 * It is safe to dereference the fd table without RCU or
484 * ->file_lock because this is the last reference to the
487 fdt = files_fdtable(files);
491 if (i >= fdt->max_fds)
493 set = fdt->open_fds->fds_bits[j++];
496 struct file * file = xchg(&fdt->fd[i], NULL);
498 filp_close(file, files);
508 struct files_struct *get_files_struct(struct task_struct *task)
510 struct files_struct *files;
515 atomic_inc(&files->count);
521 void put_files_struct(struct files_struct *files)
525 if (atomic_dec_and_test(&files->count)) {
528 * Free the fd and fdset arrays if we expanded them.
529 * If the fdtable was embedded, pass files for freeing
530 * at the end of the RCU grace period. Otherwise,
531 * you can free files immediately.
533 fdt = files_fdtable(files);
534 if (fdt != &files->fdtab)
535 kmem_cache_free(files_cachep, files);
540 void reset_files_struct(struct files_struct *files)
542 struct task_struct *tsk = current;
543 struct files_struct *old;
549 put_files_struct(old);
552 void exit_files(struct task_struct *tsk)
554 struct files_struct * files = tsk->files;
560 put_files_struct(files);
564 void put_fs_struct(struct fs_struct *fs)
566 /* No need to hold fs->lock if we are killing it */
567 if (atomic_dec_and_test(&fs->count)) {
570 if (fs->altroot.dentry)
571 path_put(&fs->altroot);
572 kmem_cache_free(fs_cachep, fs);
576 void exit_fs(struct task_struct *tsk)
578 struct fs_struct * fs = tsk->fs;
588 EXPORT_SYMBOL_GPL(exit_fs);
590 #ifdef CONFIG_MM_OWNER
592 * Task p is exiting and it owned mm, lets find a new owner for it
595 mm_need_new_owner(struct mm_struct *mm, struct task_struct *p)
598 * If there are other users of the mm and the owner (us) is exiting
599 * we need to find a new owner to take on the responsibility.
603 if (atomic_read(&mm->mm_users) <= 1)
610 void mm_update_next_owner(struct mm_struct *mm)
612 struct task_struct *c, *g, *p = current;
615 if (!mm_need_new_owner(mm, p))
618 read_lock(&tasklist_lock);
620 * Search in the children
622 list_for_each_entry(c, &p->children, sibling) {
624 goto assign_new_owner;
628 * Search in the siblings
630 list_for_each_entry(c, &p->parent->children, sibling) {
632 goto assign_new_owner;
636 * Search through everything else. We should not get
639 do_each_thread(g, c) {
641 goto assign_new_owner;
642 } while_each_thread(g, c);
644 read_unlock(&tasklist_lock);
651 * The task_lock protects c->mm from changing.
652 * We always want mm->owner->mm == mm
656 * Delay read_unlock() till we have the task_lock()
657 * to ensure that c does not slip away underneath us
659 read_unlock(&tasklist_lock);
665 cgroup_mm_owner_callbacks(mm->owner, c);
670 #endif /* CONFIG_MM_OWNER */
673 * Turn us into a lazy TLB process if we
676 static void exit_mm(struct task_struct * tsk)
678 struct mm_struct *mm = tsk->mm;
679 struct core_state *core_state;
685 * Serialize with any possible pending coredump.
686 * We must hold mmap_sem around checking core_state
687 * and clearing tsk->mm. The core-inducing thread
688 * will increment ->nr_threads for each thread in the
689 * group with ->mm != NULL.
691 down_read(&mm->mmap_sem);
692 core_state = mm->core_state;
694 struct core_thread self;
695 up_read(&mm->mmap_sem);
698 self.next = xchg(&core_state->dumper.next, &self);
700 * Implies mb(), the result of xchg() must be visible
701 * to core_state->dumper.
703 if (atomic_dec_and_test(&core_state->nr_threads))
704 complete(&core_state->startup);
707 set_task_state(tsk, TASK_UNINTERRUPTIBLE);
708 if (!self.task) /* see coredump_finish() */
712 __set_task_state(tsk, TASK_RUNNING);
713 down_read(&mm->mmap_sem);
715 atomic_inc(&mm->mm_count);
716 BUG_ON(mm != tsk->active_mm);
717 /* more a memory barrier than a real lock */
720 up_read(&mm->mmap_sem);
721 enter_lazy_tlb(mm, current);
722 /* We don't want this task to be frozen prematurely */
723 clear_freeze_flag(tsk);
725 mm_update_next_owner(mm);
730 * Return nonzero if @parent's children should reap themselves.
732 * Called with write_lock_irq(&tasklist_lock) held.
734 static int ignoring_children(struct task_struct *parent)
737 struct sighand_struct *psig = parent->sighand;
739 spin_lock_irqsave(&psig->siglock, flags);
740 ret = (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
741 (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT));
742 spin_unlock_irqrestore(&psig->siglock, flags);
747 * Detach all tasks we were using ptrace on.
748 * Any that need to be release_task'd are put on the @dead list.
750 * Called with write_lock(&tasklist_lock) held.
752 static void ptrace_exit(struct task_struct *parent, struct list_head *dead)
754 struct task_struct *p, *n;
757 list_for_each_entry_safe(p, n, &parent->ptraced, ptrace_entry) {
760 if (p->exit_state != EXIT_ZOMBIE)
764 * If it's a zombie, our attachedness prevented normal
765 * parent notification or self-reaping. Do notification
766 * now if it would have happened earlier. If it should
767 * reap itself, add it to the @dead list. We can't call
768 * release_task() here because we already hold tasklist_lock.
770 * If it's our own child, there is no notification to do.
771 * But if our normal children self-reap, then this child
772 * was prevented by ptrace and we must reap it now.
774 if (!task_detached(p) && thread_group_empty(p)) {
775 if (!same_thread_group(p->real_parent, parent))
776 do_notify_parent(p, p->exit_signal);
779 ign = ignoring_children(parent);
785 if (task_detached(p)) {
787 * Mark it as in the process of being reaped.
789 p->exit_state = EXIT_DEAD;
790 list_add(&p->ptrace_entry, dead);
796 * Finish up exit-time ptrace cleanup.
798 * Called without locks.
800 static void ptrace_exit_finish(struct task_struct *parent,
801 struct list_head *dead)
803 struct task_struct *p, *n;
805 BUG_ON(!list_empty(&parent->ptraced));
807 list_for_each_entry_safe(p, n, dead, ptrace_entry) {
808 list_del_init(&p->ptrace_entry);
813 static void reparent_thread(struct task_struct *p, struct task_struct *father)
815 if (p->pdeath_signal)
816 /* We already hold the tasklist_lock here. */
817 group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);
819 list_move_tail(&p->sibling, &p->real_parent->children);
821 /* If this is a threaded reparent there is no need to
822 * notify anyone anything has happened.
824 if (same_thread_group(p->real_parent, father))
827 /* We don't want people slaying init. */
828 if (!task_detached(p))
829 p->exit_signal = SIGCHLD;
831 /* If we'd notified the old parent about this child's death,
832 * also notify the new parent.
834 if (!ptrace_reparented(p) &&
835 p->exit_state == EXIT_ZOMBIE &&
836 !task_detached(p) && thread_group_empty(p))
837 do_notify_parent(p, p->exit_signal);
839 kill_orphaned_pgrp(p, father);
843 * When we die, we re-parent all our children.
844 * Try to give them to another thread in our thread
845 * group, and if no such member exists, give it to
846 * the child reaper process (ie "init") in our pid
849 static void forget_original_parent(struct task_struct *father)
851 struct task_struct *p, *n, *reaper = father;
852 LIST_HEAD(ptrace_dead);
854 write_lock_irq(&tasklist_lock);
857 * First clean up ptrace if we were using it.
859 ptrace_exit(father, &ptrace_dead);
862 reaper = next_thread(reaper);
863 if (reaper == father) {
864 reaper = task_child_reaper(father);
867 } while (reaper->flags & PF_EXITING);
869 list_for_each_entry_safe(p, n, &father->children, sibling) {
870 p->real_parent = reaper;
871 if (p->parent == father) {
873 p->parent = p->real_parent;
875 reparent_thread(p, father);
878 write_unlock_irq(&tasklist_lock);
879 BUG_ON(!list_empty(&father->children));
881 ptrace_exit_finish(father, &ptrace_dead);
885 * Send signals to all our closest relatives so that they know
886 * to properly mourn us..
888 static void exit_notify(struct task_struct *tsk, int group_dead)
893 * This does two things:
895 * A. Make init inherit all the child processes
896 * B. Check to see if any process groups have become orphaned
897 * as a result of our exiting, and if they have any stopped
898 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
900 forget_original_parent(tsk);
901 exit_task_namespaces(tsk);
903 write_lock_irq(&tasklist_lock);
905 kill_orphaned_pgrp(tsk->group_leader, NULL);
907 /* Let father know we died
909 * Thread signals are configurable, but you aren't going to use
910 * that to send signals to arbitary processes.
911 * That stops right now.
913 * If the parent exec id doesn't match the exec id we saved
914 * when we started then we know the parent has changed security
917 * If our self_exec id doesn't match our parent_exec_id then
918 * we have changed execution domain as these two values started
919 * the same after a fork.
921 if (tsk->exit_signal != SIGCHLD && !task_detached(tsk) &&
922 (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
923 tsk->self_exec_id != tsk->parent_exec_id) &&
925 tsk->exit_signal = SIGCHLD;
927 /* If something other than our normal parent is ptracing us, then
928 * send it a SIGCHLD instead of honoring exit_signal. exit_signal
929 * only has special meaning to our real parent.
931 if (!task_detached(tsk) && thread_group_empty(tsk)) {
932 int signal = ptrace_reparented(tsk) ?
933 SIGCHLD : tsk->exit_signal;
934 do_notify_parent(tsk, signal);
935 } else if (tsk->ptrace) {
936 do_notify_parent(tsk, SIGCHLD);
940 if (task_detached(tsk) && likely(!tsk->ptrace))
942 tsk->exit_state = state;
944 /* mt-exec, de_thread() is waiting for us */
945 if (thread_group_leader(tsk) &&
946 tsk->signal->notify_count < 0 &&
947 tsk->signal->group_exit_task)
948 wake_up_process(tsk->signal->group_exit_task);
950 write_unlock_irq(&tasklist_lock);
952 /* If the process is dead, release it - nobody will wait for it */
953 if (state == EXIT_DEAD)
957 #ifdef CONFIG_DEBUG_STACK_USAGE
958 static void check_stack_usage(void)
960 static DEFINE_SPINLOCK(low_water_lock);
961 static int lowest_to_date = THREAD_SIZE;
962 unsigned long *n = end_of_stack(current);
967 free = (unsigned long)n - (unsigned long)end_of_stack(current);
969 if (free >= lowest_to_date)
972 spin_lock(&low_water_lock);
973 if (free < lowest_to_date) {
974 printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
976 current->comm, free);
977 lowest_to_date = free;
979 spin_unlock(&low_water_lock);
982 static inline void check_stack_usage(void) {}
985 static inline void exit_child_reaper(struct task_struct *tsk)
987 if (likely(tsk->group_leader != task_child_reaper(tsk)))
990 if (tsk->nsproxy->pid_ns == &init_pid_ns)
991 panic("Attempted to kill init!");
994 * @tsk is the last thread in the 'cgroup-init' and is exiting.
995 * Terminate all remaining processes in the namespace and reap them
996 * before exiting @tsk.
998 * Note that @tsk (last thread of cgroup-init) may not necessarily
999 * be the child-reaper (i.e main thread of cgroup-init) of the
1000 * namespace i.e the child_reaper may have already exited.
1002 * Even after a child_reaper exits, we let it inherit orphaned children,
1003 * because, pid_ns->child_reaper remains valid as long as there is
1004 * at least one living sub-thread in the cgroup init.
1006 * This living sub-thread of the cgroup-init will be notified when
1007 * a child inherited by the 'child-reaper' exits (do_notify_parent()
1008 * uses __group_send_sig_info()). Further, when reaping child processes,
1009 * do_wait() iterates over children of all living sub threads.
1011 * i.e even though 'child_reaper' thread is listed as the parent of the
1012 * orphaned children, any living sub-thread in the cgroup-init can
1013 * perform the role of the child_reaper.
1015 zap_pid_ns_processes(tsk->nsproxy->pid_ns);
1018 NORET_TYPE void do_exit(long code)
1020 struct task_struct *tsk = current;
1023 profile_task_exit(tsk);
1025 WARN_ON(atomic_read(&tsk->fs_excl));
1027 if (unlikely(in_interrupt()))
1028 panic("Aiee, killing interrupt handler!");
1029 if (unlikely(!tsk->pid))
1030 panic("Attempted to kill the idle task!");
1032 if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
1033 current->ptrace_message = code;
1034 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
1038 * We're taking recursive faults here in do_exit. Safest is to just
1039 * leave this task alone and wait for reboot.
1041 if (unlikely(tsk->flags & PF_EXITING)) {
1043 "Fixing recursive fault but reboot is needed!\n");
1045 * We can do this unlocked here. The futex code uses
1046 * this flag just to verify whether the pi state
1047 * cleanup has been done or not. In the worst case it
1048 * loops once more. We pretend that the cleanup was
1049 * done as there is no way to return. Either the
1050 * OWNER_DIED bit is set by now or we push the blocked
1051 * task into the wait for ever nirwana as well.
1053 tsk->flags |= PF_EXITPIDONE;
1054 if (tsk->io_context)
1056 set_current_state(TASK_UNINTERRUPTIBLE);
1060 exit_signals(tsk); /* sets PF_EXITING */
1062 * tsk->flags are checked in the futex code to protect against
1063 * an exiting task cleaning up the robust pi futexes.
1066 spin_unlock_wait(&tsk->pi_lock);
1068 if (unlikely(in_atomic()))
1069 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
1070 current->comm, task_pid_nr(current),
1073 acct_update_integrals(tsk);
1075 update_hiwater_rss(tsk->mm);
1076 update_hiwater_vm(tsk->mm);
1078 group_dead = atomic_dec_and_test(&tsk->signal->live);
1080 exit_child_reaper(tsk);
1081 hrtimer_cancel(&tsk->signal->real_timer);
1082 exit_itimers(tsk->signal);
1084 acct_collect(code, group_dead);
1086 if (unlikely(tsk->robust_list))
1087 exit_robust_list(tsk);
1088 #ifdef CONFIG_COMPAT
1089 if (unlikely(tsk->compat_robust_list))
1090 compat_exit_robust_list(tsk);
1095 if (unlikely(tsk->audit_context))
1098 tsk->exit_code = code;
1099 taskstats_exit(tsk, group_dead);
1108 check_stack_usage();
1110 cgroup_exit(tsk, 1);
1113 if (group_dead && tsk->signal->leader)
1114 disassociate_ctty(1);
1116 module_put(task_thread_info(tsk)->exec_domain->module);
1118 module_put(tsk->binfmt->module);
1120 proc_exit_connector(tsk);
1121 exit_notify(tsk, group_dead);
1123 mpol_put(tsk->mempolicy);
1124 tsk->mempolicy = NULL;
1128 * This must happen late, after the PID is not
1131 if (unlikely(!list_empty(&tsk->pi_state_list)))
1132 exit_pi_state_list(tsk);
1133 if (unlikely(current->pi_state_cache))
1134 kfree(current->pi_state_cache);
1137 * Make sure we are holding no locks:
1139 debug_check_no_locks_held(tsk);
1141 * We can do this unlocked here. The futex code uses this flag
1142 * just to verify whether the pi state cleanup has been done
1143 * or not. In the worst case it loops once more.
1145 tsk->flags |= PF_EXITPIDONE;
1147 if (tsk->io_context)
1150 if (tsk->splice_pipe)
1151 __free_pipe_info(tsk->splice_pipe);
1154 /* causes final put_task_struct in finish_task_switch(). */
1155 tsk->state = TASK_DEAD;
1159 /* Avoid "noreturn function does return". */
1161 cpu_relax(); /* For when BUG is null */
1164 EXPORT_SYMBOL_GPL(do_exit);
1166 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
1174 EXPORT_SYMBOL(complete_and_exit);
1176 asmlinkage long sys_exit(int error_code)
1178 do_exit((error_code&0xff)<<8);
1182 * Take down every thread in the group. This is called by fatal signals
1183 * as well as by sys_exit_group (below).
1186 do_group_exit(int exit_code)
1188 struct signal_struct *sig = current->signal;
1190 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
1192 if (signal_group_exit(sig))
1193 exit_code = sig->group_exit_code;
1194 else if (!thread_group_empty(current)) {
1195 struct sighand_struct *const sighand = current->sighand;
1196 spin_lock_irq(&sighand->siglock);
1197 if (signal_group_exit(sig))
1198 /* Another thread got here before we took the lock. */
1199 exit_code = sig->group_exit_code;
1201 sig->group_exit_code = exit_code;
1202 sig->flags = SIGNAL_GROUP_EXIT;
1203 zap_other_threads(current);
1205 spin_unlock_irq(&sighand->siglock);
1213 * this kills every thread in the thread group. Note that any externally
1214 * wait4()-ing process will get the correct exit code - even if this
1215 * thread is not the thread group leader.
1217 asmlinkage void sys_exit_group(int error_code)
1219 do_group_exit((error_code & 0xff) << 8);
1222 static struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
1224 struct pid *pid = NULL;
1225 if (type == PIDTYPE_PID)
1226 pid = task->pids[type].pid;
1227 else if (type < PIDTYPE_MAX)
1228 pid = task->group_leader->pids[type].pid;
1232 static int eligible_child(enum pid_type type, struct pid *pid, int options,
1233 struct task_struct *p)
1237 if (type < PIDTYPE_MAX) {
1238 if (task_pid_type(p, type) != pid)
1242 /* Wait for all children (clone and not) if __WALL is set;
1243 * otherwise, wait for clone children *only* if __WCLONE is
1244 * set; otherwise, wait for non-clone children *only*. (Note:
1245 * A "clone" child here is one that reports to its parent
1246 * using a signal other than SIGCHLD.) */
1247 if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
1248 && !(options & __WALL))
1251 err = security_task_wait(p);
1258 static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
1259 int why, int status,
1260 struct siginfo __user *infop,
1261 struct rusage __user *rusagep)
1263 int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1267 retval = put_user(SIGCHLD, &infop->si_signo);
1269 retval = put_user(0, &infop->si_errno);
1271 retval = put_user((short)why, &infop->si_code);
1273 retval = put_user(pid, &infop->si_pid);
1275 retval = put_user(uid, &infop->si_uid);
1277 retval = put_user(status, &infop->si_status);
1284 * Handle sys_wait4 work for one task in state EXIT_ZOMBIE. We hold
1285 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1286 * the lock and this task is uninteresting. If we return nonzero, we have
1287 * released the lock and the system call should return.
1289 static int wait_task_zombie(struct task_struct *p, int options,
1290 struct siginfo __user *infop,
1291 int __user *stat_addr, struct rusage __user *ru)
1293 unsigned long state;
1294 int retval, status, traced;
1295 pid_t pid = task_pid_vnr(p);
1297 if (!likely(options & WEXITED))
1300 if (unlikely(options & WNOWAIT)) {
1302 int exit_code = p->exit_code;
1306 read_unlock(&tasklist_lock);
1307 if ((exit_code & 0x7f) == 0) {
1309 status = exit_code >> 8;
1311 why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
1312 status = exit_code & 0x7f;
1314 return wait_noreap_copyout(p, pid, uid, why,
1319 * Try to move the task's state to DEAD
1320 * only one thread is allowed to do this:
1322 state = xchg(&p->exit_state, EXIT_DEAD);
1323 if (state != EXIT_ZOMBIE) {
1324 BUG_ON(state != EXIT_DEAD);
1328 traced = ptrace_reparented(p);
1330 if (likely(!traced)) {
1331 struct signal_struct *psig;
1332 struct signal_struct *sig;
1335 * The resource counters for the group leader are in its
1336 * own task_struct. Those for dead threads in the group
1337 * are in its signal_struct, as are those for the child
1338 * processes it has previously reaped. All these
1339 * accumulate in the parent's signal_struct c* fields.
1341 * We don't bother to take a lock here to protect these
1342 * p->signal fields, because they are only touched by
1343 * __exit_signal, which runs with tasklist_lock
1344 * write-locked anyway, and so is excluded here. We do
1345 * need to protect the access to p->parent->signal fields,
1346 * as other threads in the parent group can be right
1347 * here reaping other children at the same time.
1349 spin_lock_irq(&p->parent->sighand->siglock);
1350 psig = p->parent->signal;
1353 cputime_add(psig->cutime,
1354 cputime_add(p->utime,
1355 cputime_add(sig->utime,
1358 cputime_add(psig->cstime,
1359 cputime_add(p->stime,
1360 cputime_add(sig->stime,
1363 cputime_add(psig->cgtime,
1364 cputime_add(p->gtime,
1365 cputime_add(sig->gtime,
1368 p->min_flt + sig->min_flt + sig->cmin_flt;
1370 p->maj_flt + sig->maj_flt + sig->cmaj_flt;
1372 p->nvcsw + sig->nvcsw + sig->cnvcsw;
1374 p->nivcsw + sig->nivcsw + sig->cnivcsw;
1376 task_io_get_inblock(p) +
1377 sig->inblock + sig->cinblock;
1379 task_io_get_oublock(p) +
1380 sig->oublock + sig->coublock;
1381 #ifdef CONFIG_TASK_XACCT
1382 psig->rchar += p->rchar + sig->rchar;
1383 psig->wchar += p->wchar + sig->wchar;
1384 psig->syscr += p->syscr + sig->syscr;
1385 psig->syscw += p->syscw + sig->syscw;
1386 #endif /* CONFIG_TASK_XACCT */
1387 #ifdef CONFIG_TASK_IO_ACCOUNTING
1388 psig->ioac.read_bytes +=
1389 p->ioac.read_bytes + sig->ioac.read_bytes;
1390 psig->ioac.write_bytes +=
1391 p->ioac.write_bytes + sig->ioac.write_bytes;
1392 psig->ioac.cancelled_write_bytes +=
1393 p->ioac.cancelled_write_bytes +
1394 sig->ioac.cancelled_write_bytes;
1395 #endif /* CONFIG_TASK_IO_ACCOUNTING */
1396 spin_unlock_irq(&p->parent->sighand->siglock);
1400 * Now we are sure this task is interesting, and no other
1401 * thread can reap it because we set its state to EXIT_DEAD.
1403 read_unlock(&tasklist_lock);
1405 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1406 status = (p->signal->flags & SIGNAL_GROUP_EXIT)
1407 ? p->signal->group_exit_code : p->exit_code;
1408 if (!retval && stat_addr)
1409 retval = put_user(status, stat_addr);
1410 if (!retval && infop)
1411 retval = put_user(SIGCHLD, &infop->si_signo);
1412 if (!retval && infop)
1413 retval = put_user(0, &infop->si_errno);
1414 if (!retval && infop) {
1417 if ((status & 0x7f) == 0) {
1421 why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
1424 retval = put_user((short)why, &infop->si_code);
1426 retval = put_user(status, &infop->si_status);
1428 if (!retval && infop)
1429 retval = put_user(pid, &infop->si_pid);
1430 if (!retval && infop)
1431 retval = put_user(p->uid, &infop->si_uid);
1436 write_lock_irq(&tasklist_lock);
1437 /* We dropped tasklist, ptracer could die and untrace */
1440 * If this is not a detached task, notify the parent.
1441 * If it's still not detached after that, don't release
1444 if (!task_detached(p)) {
1445 do_notify_parent(p, p->exit_signal);
1446 if (!task_detached(p)) {
1447 p->exit_state = EXIT_ZOMBIE;
1451 write_unlock_irq(&tasklist_lock);
1460 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1461 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1462 * the lock and this task is uninteresting. If we return nonzero, we have
1463 * released the lock and the system call should return.
1465 static int wait_task_stopped(int ptrace, struct task_struct *p,
1466 int options, struct siginfo __user *infop,
1467 int __user *stat_addr, struct rusage __user *ru)
1469 int retval, exit_code, why;
1470 uid_t uid = 0; /* unneeded, required by compiler */
1473 if (!(options & WUNTRACED))
1477 spin_lock_irq(&p->sighand->siglock);
1479 if (unlikely(!task_is_stopped_or_traced(p)))
1482 if (!ptrace && p->signal->group_stop_count > 0)
1484 * A group stop is in progress and this is the group leader.
1485 * We won't report until all threads have stopped.
1489 exit_code = p->exit_code;
1493 if (!unlikely(options & WNOWAIT))
1498 spin_unlock_irq(&p->sighand->siglock);
1503 * Now we are pretty sure this task is interesting.
1504 * Make sure it doesn't get reaped out from under us while we
1505 * give up the lock and then examine it below. We don't want to
1506 * keep holding onto the tasklist_lock while we call getrusage and
1507 * possibly take page faults for user memory.
1510 pid = task_pid_vnr(p);
1511 why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
1512 read_unlock(&tasklist_lock);
1514 if (unlikely(options & WNOWAIT))
1515 return wait_noreap_copyout(p, pid, uid,
1519 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1520 if (!retval && stat_addr)
1521 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1522 if (!retval && infop)
1523 retval = put_user(SIGCHLD, &infop->si_signo);
1524 if (!retval && infop)
1525 retval = put_user(0, &infop->si_errno);
1526 if (!retval && infop)
1527 retval = put_user((short)why, &infop->si_code);
1528 if (!retval && infop)
1529 retval = put_user(exit_code, &infop->si_status);
1530 if (!retval && infop)
1531 retval = put_user(pid, &infop->si_pid);
1532 if (!retval && infop)
1533 retval = put_user(uid, &infop->si_uid);
1543 * Handle do_wait work for one task in a live, non-stopped state.
1544 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1545 * the lock and this task is uninteresting. If we return nonzero, we have
1546 * released the lock and the system call should return.
1548 static int wait_task_continued(struct task_struct *p, int options,
1549 struct siginfo __user *infop,
1550 int __user *stat_addr, struct rusage __user *ru)
1556 if (!unlikely(options & WCONTINUED))
1559 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
1562 spin_lock_irq(&p->sighand->siglock);
1563 /* Re-check with the lock held. */
1564 if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
1565 spin_unlock_irq(&p->sighand->siglock);
1568 if (!unlikely(options & WNOWAIT))
1569 p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1570 spin_unlock_irq(&p->sighand->siglock);
1572 pid = task_pid_vnr(p);
1575 read_unlock(&tasklist_lock);
1578 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1580 if (!retval && stat_addr)
1581 retval = put_user(0xffff, stat_addr);
1585 retval = wait_noreap_copyout(p, pid, uid,
1586 CLD_CONTINUED, SIGCONT,
1588 BUG_ON(retval == 0);
1595 * Consider @p for a wait by @parent.
1597 * -ECHILD should be in *@notask_error before the first call.
1598 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1599 * Returns zero if the search for a child should continue;
1600 * then *@notask_error is 0 if @p is an eligible child,
1601 * or another error from security_task_wait(), or still -ECHILD.
1603 static int wait_consider_task(struct task_struct *parent, int ptrace,
1604 struct task_struct *p, int *notask_error,
1605 enum pid_type type, struct pid *pid, int options,
1606 struct siginfo __user *infop,
1607 int __user *stat_addr, struct rusage __user *ru)
1609 int ret = eligible_child(type, pid, options, p);
1613 if (unlikely(ret < 0)) {
1615 * If we have not yet seen any eligible child,
1616 * then let this error code replace -ECHILD.
1617 * A permission error will give the user a clue
1618 * to look for security policy problems, rather
1619 * than for mysterious wait bugs.
1622 *notask_error = ret;
1625 if (likely(!ptrace) && unlikely(p->ptrace)) {
1627 * This child is hidden by ptrace.
1628 * We aren't allowed to see it now, but eventually we will.
1634 if (p->exit_state == EXIT_DEAD)
1638 * We don't reap group leaders with subthreads.
1640 if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p))
1641 return wait_task_zombie(p, options, infop, stat_addr, ru);
1644 * It's stopped or running now, so it might
1645 * later continue, exit, or stop again.
1649 if (task_is_stopped_or_traced(p))
1650 return wait_task_stopped(ptrace, p, options,
1651 infop, stat_addr, ru);
1653 return wait_task_continued(p, options, infop, stat_addr, ru);
1657 * Do the work of do_wait() for one thread in the group, @tsk.
1659 * -ECHILD should be in *@notask_error before the first call.
1660 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
1661 * Returns zero if the search for a child should continue; then
1662 * *@notask_error is 0 if there were any eligible children,
1663 * or another error from security_task_wait(), or still -ECHILD.
1665 static int do_wait_thread(struct task_struct *tsk, int *notask_error,
1666 enum pid_type type, struct pid *pid, int options,
1667 struct siginfo __user *infop, int __user *stat_addr,
1668 struct rusage __user *ru)
1670 struct task_struct *p;
1672 list_for_each_entry(p, &tsk->children, sibling) {
1674 * Do not consider detached threads.
1676 if (!task_detached(p)) {
1677 int ret = wait_consider_task(tsk, 0, p, notask_error,
1679 infop, stat_addr, ru);
1688 static int ptrace_do_wait(struct task_struct *tsk, int *notask_error,
1689 enum pid_type type, struct pid *pid, int options,
1690 struct siginfo __user *infop, int __user *stat_addr,
1691 struct rusage __user *ru)
1693 struct task_struct *p;
1696 * Traditionally we see ptrace'd stopped tasks regardless of options.
1698 options |= WUNTRACED;
1700 list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
1701 int ret = wait_consider_task(tsk, 1, p, notask_error,
1703 infop, stat_addr, ru);
1711 static long do_wait(enum pid_type type, struct pid *pid, int options,
1712 struct siginfo __user *infop, int __user *stat_addr,
1713 struct rusage __user *ru)
1715 DECLARE_WAITQUEUE(wait, current);
1716 struct task_struct *tsk;
1719 add_wait_queue(¤t->signal->wait_chldexit,&wait);
1722 * If there is nothing that can match our critiera just get out.
1723 * We will clear @retval to zero if we see any child that might later
1724 * match our criteria, even if we are not able to reap it yet.
1727 if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type])))
1730 current->state = TASK_INTERRUPTIBLE;
1731 read_lock(&tasklist_lock);
1734 int tsk_result = do_wait_thread(tsk, &retval,
1736 infop, stat_addr, ru);
1738 tsk_result = ptrace_do_wait(tsk, &retval,
1740 infop, stat_addr, ru);
1743 * tasklist_lock is unlocked and we have a final result.
1745 retval = tsk_result;
1749 if (options & __WNOTHREAD)
1751 tsk = next_thread(tsk);
1752 BUG_ON(tsk->signal != current->signal);
1753 } while (tsk != current);
1754 read_unlock(&tasklist_lock);
1756 if (!retval && !(options & WNOHANG)) {
1757 retval = -ERESTARTSYS;
1758 if (!signal_pending(current)) {
1765 current->state = TASK_RUNNING;
1766 remove_wait_queue(¤t->signal->wait_chldexit,&wait);
1772 * For a WNOHANG return, clear out all the fields
1773 * we would set so the user can easily tell the
1777 retval = put_user(0, &infop->si_signo);
1779 retval = put_user(0, &infop->si_errno);
1781 retval = put_user(0, &infop->si_code);
1783 retval = put_user(0, &infop->si_pid);
1785 retval = put_user(0, &infop->si_uid);
1787 retval = put_user(0, &infop->si_status);
1793 asmlinkage long sys_waitid(int which, pid_t upid,
1794 struct siginfo __user *infop, int options,
1795 struct rusage __user *ru)
1797 struct pid *pid = NULL;
1801 if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
1803 if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
1816 type = PIDTYPE_PGID;
1824 if (type < PIDTYPE_MAX)
1825 pid = find_get_pid(upid);
1826 ret = do_wait(type, pid, options, infop, NULL, ru);
1829 /* avoid REGPARM breakage on x86: */
1830 asmlinkage_protect(5, ret, which, upid, infop, options, ru);
1834 asmlinkage long sys_wait4(pid_t upid, int __user *stat_addr,
1835 int options, struct rusage __user *ru)
1837 struct pid *pid = NULL;
1841 if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
1842 __WNOTHREAD|__WCLONE|__WALL))
1847 else if (upid < 0) {
1848 type = PIDTYPE_PGID;
1849 pid = find_get_pid(-upid);
1850 } else if (upid == 0) {
1851 type = PIDTYPE_PGID;
1852 pid = get_pid(task_pgrp(current));
1853 } else /* upid > 0 */ {
1855 pid = find_get_pid(upid);
1858 ret = do_wait(type, pid, options | WEXITED, NULL, stat_addr, ru);
1861 /* avoid REGPARM breakage on x86: */
1862 asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
1866 #ifdef __ARCH_WANT_SYS_WAITPID
1869 * sys_waitpid() remains for compatibility. waitpid() should be
1870 * implemented by calling sys_wait4() from libc.a.
1872 asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
1874 return sys_wait4(pid, stat_addr, options, NULL);