4 * Copyright (C) 1991, 1992 Linus Torvalds
7 #include <linux/config.h>
9 #include <linux/slab.h>
10 #include <linux/interrupt.h>
11 #include <linux/smp_lock.h>
12 #include <linux/module.h>
13 #include <linux/completion.h>
14 #include <linux/personality.h>
15 #include <linux/tty.h>
16 #include <linux/namespace.h>
17 #include <linux/security.h>
18 #include <linux/acct.h>
19 #include <linux/file.h>
20 #include <linux/binfmts.h>
21 #include <linux/ptrace.h>
22 #include <linux/profile.h>
23 #include <linux/mount.h>
24 #include <linux/proc_fs.h>
26 #include <asm/uaccess.h>
27 #include <asm/pgtable.h>
28 #include <asm/mmu_context.h>
30 extern void sem_exit (void);
31 extern struct task_struct *child_reaper;
33 int getrusage(struct task_struct *, int, struct rusage *);
35 static void __unhash_process(struct task_struct *p)
38 detach_pid(p, PIDTYPE_PID);
39 detach_pid(p, PIDTYPE_TGID);
40 if (thread_group_leader(p)) {
41 detach_pid(p, PIDTYPE_PGID);
42 detach_pid(p, PIDTYPE_SID);
44 __get_cpu_var(process_counts)--;
50 void release_task(struct task_struct * p)
54 struct dentry *proc_dentry;
57 BUG_ON(p->state < TASK_ZOMBIE);
59 atomic_dec(&p->user->processes);
60 spin_lock(&p->proc_lock);
61 proc_dentry = proc_pid_unhash(p);
62 write_lock_irq(&tasklist_lock);
63 if (unlikely(p->ptrace))
65 BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
71 * If we are the last non-leader member of the thread
72 * group, and the leader is zombie, then notify the
73 * group leader's parent process. (if it wants notification.)
76 leader = p->group_leader;
77 if (leader != p && thread_group_empty(leader) && leader->state == TASK_ZOMBIE) {
78 BUG_ON(leader->exit_signal == -1);
79 do_notify_parent(leader, leader->exit_signal);
81 * If we were the last child thread and the leader has
82 * exited already, and the leader's parent ignores SIGCHLD,
83 * then we are the one who should release the leader.
85 * do_notify_parent() will have marked it self-reaping in
88 zap_leader = (leader->exit_signal == -1);
91 p->parent->cutime += p->utime + p->cutime;
92 p->parent->cstime += p->stime + p->cstime;
93 p->parent->cmin_flt += p->min_flt + p->cmin_flt;
94 p->parent->cmaj_flt += p->maj_flt + p->cmaj_flt;
95 p->parent->cnvcsw += p->nvcsw + p->cnvcsw;
96 p->parent->cnivcsw += p->nivcsw + p->cnivcsw;
98 write_unlock_irq(&tasklist_lock);
99 spin_unlock(&p->proc_lock);
100 proc_pid_flush(proc_dentry);
105 if (unlikely(zap_leader))
109 /* we are using it only for SMP init */
111 void unhash_process(struct task_struct *p)
113 struct dentry *proc_dentry;
115 spin_lock(&p->proc_lock);
116 proc_dentry = proc_pid_unhash(p);
117 write_lock_irq(&tasklist_lock);
119 write_unlock_irq(&tasklist_lock);
120 spin_unlock(&p->proc_lock);
121 proc_pid_flush(proc_dentry);
125 * This checks not only the pgrp, but falls back on the pid if no
126 * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
129 int session_of_pgrp(int pgrp)
131 struct task_struct *p;
136 read_lock(&tasklist_lock);
137 for_each_task_pid(pgrp, PIDTYPE_PGID, p, l, pid)
138 if (p->signal->session > 0) {
139 sid = p->signal->session;
142 p = find_task_by_pid(pgrp);
144 sid = p->signal->session;
146 read_unlock(&tasklist_lock);
152 * Determine if a process group is "orphaned", according to the POSIX
153 * definition in 2.2.2.52. Orphaned process groups are not to be affected
154 * by terminal-generated stop signals. Newly orphaned process groups are
155 * to receive a SIGHUP and a SIGCONT.
157 * "I ask you, have you ever known what it is to be an orphan?"
159 static int will_become_orphaned_pgrp(int pgrp, task_t *ignored_task)
161 struct task_struct *p;
166 for_each_task_pid(pgrp, PIDTYPE_PGID, p, l, pid) {
167 if (p == ignored_task
168 || p->state >= TASK_ZOMBIE
169 || p->real_parent->pid == 1)
171 if (process_group(p->real_parent) != pgrp
172 && p->real_parent->signal->session == p->signal->session) {
177 return ret; /* (sighing) "Often!" */
180 int is_orphaned_pgrp(int pgrp)
184 read_lock(&tasklist_lock);
185 retval = will_become_orphaned_pgrp(pgrp, NULL);
186 read_unlock(&tasklist_lock);
191 static inline int has_stopped_jobs(int pgrp)
194 struct task_struct *p;
198 for_each_task_pid(pgrp, PIDTYPE_PGID, p, l, pid) {
199 if (p->state != TASK_STOPPED)
202 /* If p is stopped by a debugger on a signal that won't
203 stop it, then don't count p as stopped. This isn't
204 perfect but it's a good approximation. */
205 if (unlikely (p->ptrace)
206 && p->exit_code != SIGSTOP
207 && p->exit_code != SIGTSTP
208 && p->exit_code != SIGTTOU
209 && p->exit_code != SIGTTIN)
219 * reparent_to_init() - Reparent the calling kernel thread to the init task.
221 * If a kernel thread is launched as a result of a system call, or if
222 * it ever exits, it should generally reparent itself to init so that
223 * it is correctly cleaned up on exit.
225 * The various task state such as scheduling policy and priority may have
226 * been inherited from a user process, so we reset them to sane values here.
228 * NOTE that reparent_to_init() gives the caller full capabilities.
230 void reparent_to_init(void)
232 write_lock_irq(&tasklist_lock);
234 ptrace_unlink(current);
235 /* Reparent to init */
236 REMOVE_LINKS(current);
237 current->parent = child_reaper;
238 current->real_parent = child_reaper;
241 /* Set the exit signal to SIGCHLD so we signal init on exit */
242 current->exit_signal = SIGCHLD;
244 if ((current->policy == SCHED_NORMAL) && (task_nice(current) < 0))
245 set_user_nice(current, 0);
249 security_task_reparent_to_init(current);
250 memcpy(current->rlim, init_task.rlim, sizeof(*(current->rlim)));
251 atomic_inc(&(INIT_USER->__count));
252 switch_uid(INIT_USER);
254 write_unlock_irq(&tasklist_lock);
257 void __set_special_pids(pid_t session, pid_t pgrp)
259 struct task_struct *curr = current;
261 if (curr->signal->session != session) {
262 detach_pid(curr, PIDTYPE_SID);
263 curr->signal->session = session;
264 attach_pid(curr, PIDTYPE_SID, session);
266 if (process_group(curr) != pgrp) {
267 detach_pid(curr, PIDTYPE_PGID);
268 curr->signal->pgrp = pgrp;
269 attach_pid(curr, PIDTYPE_PGID, pgrp);
273 void set_special_pids(pid_t session, pid_t pgrp)
275 write_lock_irq(&tasklist_lock);
276 __set_special_pids(session, pgrp);
277 write_unlock_irq(&tasklist_lock);
281 * Let kernel threads use this to say that they
282 * allow a certain signal (since daemonize() will
283 * have disabled all of them by default).
285 int allow_signal(int sig)
287 if (sig < 1 || sig > _NSIG)
290 spin_lock_irq(¤t->sighand->siglock);
291 sigdelset(¤t->blocked, sig);
293 /* Kernel threads handle their own signals.
294 Let the signal code know it'll be handled, so
295 that they don't get converted to SIGKILL or
296 just silently dropped */
297 current->sighand->action[(sig)-1].sa.sa_handler = (void *)2;
300 spin_unlock_irq(¤t->sighand->siglock);
304 EXPORT_SYMBOL(allow_signal);
306 int disallow_signal(int sig)
308 if (sig < 1 || sig > _NSIG)
311 spin_lock_irq(¤t->sighand->siglock);
312 sigaddset(¤t->blocked, sig);
314 spin_unlock_irq(¤t->sighand->siglock);
318 EXPORT_SYMBOL(disallow_signal);
321 * Put all the gunge required to become a kernel thread without
322 * attached user resources in one place where it belongs.
325 void daemonize(const char *name, ...)
328 struct fs_struct *fs;
331 va_start(args, name);
332 vsnprintf(current->comm, sizeof(current->comm), name, args);
336 * If we were started as result of loading a module, close all of the
337 * user space pages. We don't need them, and if we didn't close them
338 * they would be locked into memory.
342 set_special_pids(1, 1);
343 current->signal->tty = NULL;
345 /* Block and flush all signals */
346 sigfillset(&blocked);
347 sigprocmask(SIG_BLOCK, &blocked, NULL);
348 flush_signals(current);
350 /* Become as one with the init task */
352 exit_fs(current); /* current->fs->count--; */
355 atomic_inc(&fs->count);
357 current->files = init_task.files;
358 atomic_inc(¤t->files->count);
363 EXPORT_SYMBOL(daemonize);
365 static inline void close_files(struct files_struct * files)
373 if (i >= files->max_fdset || i >= files->max_fds)
375 set = files->open_fds->fds_bits[j++];
378 struct file * file = xchg(&files->fd[i], NULL);
380 filp_close(file, files);
388 struct files_struct *get_files_struct(struct task_struct *task)
390 struct files_struct *files;
395 atomic_inc(&files->count);
401 void fastcall put_files_struct(struct files_struct *files)
403 if (atomic_dec_and_test(&files->count)) {
406 * Free the fd and fdset arrays if we expanded them.
408 if (files->fd != &files->fd_array[0])
409 free_fd_array(files->fd, files->max_fds);
410 if (files->max_fdset > __FD_SETSIZE) {
411 free_fdset(files->open_fds, files->max_fdset);
412 free_fdset(files->close_on_exec, files->max_fdset);
414 kmem_cache_free(files_cachep, files);
418 EXPORT_SYMBOL(put_files_struct);
420 static inline void __exit_files(struct task_struct *tsk)
422 struct files_struct * files = tsk->files;
428 put_files_struct(files);
432 void exit_files(struct task_struct *tsk)
437 static inline void __put_fs_struct(struct fs_struct *fs)
439 /* No need to hold fs->lock if we are killing it */
440 if (atomic_dec_and_test(&fs->count)) {
447 mntput(fs->altrootmnt);
449 kmem_cache_free(fs_cachep, fs);
453 void put_fs_struct(struct fs_struct *fs)
458 static inline void __exit_fs(struct task_struct *tsk)
460 struct fs_struct * fs = tsk->fs;
470 void exit_fs(struct task_struct *tsk)
475 EXPORT_SYMBOL_GPL(exit_fs);
478 * Turn us into a lazy TLB process if we
481 static inline void __exit_mm(struct task_struct * tsk)
483 struct mm_struct *mm = tsk->mm;
489 * Serialize with any possible pending coredump.
490 * We must hold mmap_sem around checking core_waiters
491 * and clearing tsk->mm. The core-inducing thread
492 * will increment core_waiters for each thread in the
493 * group with ->mm != NULL.
495 down_read(&mm->mmap_sem);
496 if (mm->core_waiters) {
497 up_read(&mm->mmap_sem);
498 down_write(&mm->mmap_sem);
499 if (!--mm->core_waiters)
500 complete(mm->core_startup_done);
501 up_write(&mm->mmap_sem);
503 wait_for_completion(&mm->core_done);
504 down_read(&mm->mmap_sem);
506 atomic_inc(&mm->mm_count);
507 if (mm != tsk->active_mm) BUG();
508 /* more a memory barrier than a real lock */
511 up_read(&mm->mmap_sem);
512 enter_lazy_tlb(mm, current);
517 void exit_mm(struct task_struct *tsk)
522 EXPORT_SYMBOL(exit_mm);
524 static inline void choose_new_parent(task_t *p, task_t *reaper, task_t *child_reaper)
527 * Make sure we're not reparenting to ourselves and that
528 * the parent is not a zombie.
530 if (p == reaper || reaper->state >= TASK_ZOMBIE)
531 p->real_parent = child_reaper;
533 p->real_parent = reaper;
534 if (p->parent == p->real_parent)
538 static inline void reparent_thread(task_t *p, task_t *father, int traced)
540 /* We don't want people slaying init. */
541 if (p->exit_signal != -1)
542 p->exit_signal = SIGCHLD;
545 if (p->pdeath_signal)
546 /* We already hold the tasklist_lock here. */
547 group_send_sig_info(p->pdeath_signal, (void *) 0, p);
549 /* Move the child from its dying parent to the new one. */
550 if (unlikely(traced)) {
551 /* Preserve ptrace links if someone else is tracing this child. */
552 list_del_init(&p->ptrace_list);
553 if (p->parent != p->real_parent)
554 list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
556 /* If this child is being traced, then we're the one tracing it
557 * anyway, so let go of it.
560 list_del_init(&p->sibling);
561 p->parent = p->real_parent;
562 list_add_tail(&p->sibling, &p->parent->children);
564 /* If we'd notified the old parent about this child's death,
565 * also notify the new parent.
567 if (p->state == TASK_ZOMBIE && p->exit_signal != -1 &&
568 thread_group_empty(p))
569 do_notify_parent(p, p->exit_signal);
573 * process group orphan check
574 * Case ii: Our child is in a different pgrp
575 * than we are, and it was the only connection
576 * outside, so the child pgrp is now orphaned.
578 if ((process_group(p) != process_group(father)) &&
579 (p->signal->session == father->signal->session)) {
580 int pgrp = process_group(p);
582 if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {
583 __kill_pg_info(SIGHUP, (void *)1, pgrp);
584 __kill_pg_info(SIGCONT, (void *)1, pgrp);
590 * When we die, we re-parent all our children.
591 * Try to give them to another thread in our thread
592 * group, and if no such member exists, give it to
593 * the global child reaper process (ie "init")
595 static inline void forget_original_parent(struct task_struct * father)
597 struct task_struct *p, *reaper = father;
598 struct list_head *_p, *_n;
600 reaper = father->group_leader;
601 if (reaper == father)
602 reaper = child_reaper;
605 * There are only two places where our children can be:
607 * - in our child list
608 * - in our ptraced child list
610 * Search them and reparent children.
612 list_for_each_safe(_p, _n, &father->children) {
613 p = list_entry(_p,struct task_struct,sibling);
614 if (father == p->real_parent) {
615 choose_new_parent(p, reaper, child_reaper);
616 reparent_thread(p, father, 0);
619 if (p->state == TASK_ZOMBIE && p->exit_signal != -1 &&
620 thread_group_empty(p))
621 do_notify_parent(p, p->exit_signal);
624 list_for_each_safe(_p, _n, &father->ptrace_children) {
625 p = list_entry(_p,struct task_struct,ptrace_list);
626 choose_new_parent(p, reaper, child_reaper);
627 reparent_thread(p, father, 1);
632 * Send signals to all our closest relatives so that they know
633 * to properly mourn us..
635 static void exit_notify(struct task_struct *tsk)
638 struct task_struct *t;
640 if (signal_pending(tsk) && !tsk->signal->group_exit
641 && !thread_group_empty(tsk)) {
643 * This occurs when there was a race between our exit
644 * syscall and a group signal choosing us as the one to
645 * wake up. It could be that we are the only thread
646 * alerted to check for pending signals, but another thread
647 * should be woken now to take the signal since we will not.
648 * Now we'll wake all the threads in the group just to make
649 * sure someone gets all the pending signals.
651 read_lock(&tasklist_lock);
652 spin_lock_irq(&tsk->sighand->siglock);
653 for (t = next_thread(tsk); t != tsk; t = next_thread(t))
654 if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
655 recalc_sigpending_tsk(t);
656 if (signal_pending(t))
657 signal_wake_up(t, 0);
659 spin_unlock_irq(&tsk->sighand->siglock);
660 read_unlock(&tasklist_lock);
663 write_lock_irq(&tasklist_lock);
666 * This does two things:
668 * A. Make init inherit all the child processes
669 * B. Check to see if any process groups have become orphaned
670 * as a result of our exiting, and if they have any stopped
671 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
674 forget_original_parent(tsk);
675 BUG_ON(!list_empty(&tsk->children));
678 * Check to see if any process groups have become orphaned
679 * as a result of our exiting, and if they have any stopped
680 * jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
682 * Case i: Our father is in a different pgrp than we are
683 * and we were the only connection outside, so our pgrp
684 * is about to become orphaned.
687 t = tsk->real_parent;
689 if ((process_group(t) != process_group(tsk)) &&
690 (t->signal->session == tsk->signal->session) &&
691 will_become_orphaned_pgrp(process_group(tsk), tsk) &&
692 has_stopped_jobs(process_group(tsk))) {
693 __kill_pg_info(SIGHUP, (void *)1, process_group(tsk));
694 __kill_pg_info(SIGCONT, (void *)1, process_group(tsk));
697 /* Let father know we died
699 * Thread signals are configurable, but you aren't going to use
700 * that to send signals to arbitary processes.
701 * That stops right now.
703 * If the parent exec id doesn't match the exec id we saved
704 * when we started then we know the parent has changed security
707 * If our self_exec id doesn't match our parent_exec_id then
708 * we have changed execution domain as these two values started
709 * the same after a fork.
713 if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
714 ( tsk->parent_exec_id != t->self_exec_id ||
715 tsk->self_exec_id != tsk->parent_exec_id)
716 && !capable(CAP_KILL))
717 tsk->exit_signal = SIGCHLD;
720 /* If something other than our normal parent is ptracing us, then
721 * send it a SIGCHLD instead of honoring exit_signal. exit_signal
722 * only has special meaning to our real parent.
724 if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
725 int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
726 do_notify_parent(tsk, signal);
727 } else if (tsk->ptrace) {
728 do_notify_parent(tsk, SIGCHLD);
732 if (tsk->exit_signal == -1 && tsk->ptrace == 0)
735 tsk->flags |= PF_DEAD;
738 * In the preemption case it must be impossible for the task
739 * to get runnable again, so use "_raw_" unlock to keep
740 * preempt_count elevated until we schedule().
742 * To avoid deadlock on SMP, interrupts must be unmasked. If we
743 * don't, subsequently called functions (e.g, wait_task_inactive()
744 * via release_task()) will spin, with interrupt flags
745 * unwittingly blocked, until the other task sleeps. That task
746 * may itself be waiting for smp_call_function() to answer and
747 * complete, and with interrupts blocked that will never happen.
749 _raw_write_unlock(&tasklist_lock);
752 /* If the process is dead, release it - nobody will wait for it */
753 if (state == TASK_DEAD)
758 asmlinkage NORET_TYPE void do_exit(long code)
760 struct task_struct *tsk = current;
762 if (unlikely(in_interrupt()))
763 panic("Aiee, killing interrupt handler!");
764 if (unlikely(!tsk->pid))
765 panic("Attempted to kill the idle task!");
766 if (unlikely(tsk->pid == 1))
767 panic("Attempted to kill init!");
770 tsk->flags |= PF_EXITING;
771 del_timer_sync(&tsk->real_timer);
773 if (unlikely(in_atomic()))
774 printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
775 current->comm, current->pid,
778 profile_exit_task(tsk);
780 if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
781 current->ptrace_message = code;
782 ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
794 if (tsk->signal->leader)
795 disassociate_ctty(1);
797 module_put(tsk->thread_info->exec_domain->module);
799 module_put(tsk->binfmt->module);
801 tsk->exit_code = code;
805 /* Avoid "noreturn function does return". */
809 NORET_TYPE void complete_and_exit(struct completion *comp, long code)
817 EXPORT_SYMBOL(complete_and_exit);
819 asmlinkage long sys_exit(int error_code)
821 do_exit((error_code&0xff)<<8);
824 task_t fastcall *next_thread(task_t *p)
826 struct pid_link *link = p->pids + PIDTYPE_TGID;
827 struct list_head *tmp, *head = &link->pidptr->task_list;
832 if (!spin_is_locked(&p->sighand->siglock) &&
833 !rwlock_is_locked(&tasklist_lock))
836 tmp = link->pid_chain.next;
840 return pid_task(tmp, PIDTYPE_TGID);
843 EXPORT_SYMBOL(next_thread);
846 * Take down every thread in the group. This is called by fatal signals
847 * as well as by sys_exit_group (below).
850 do_group_exit(int exit_code)
852 BUG_ON(exit_code & 0x80); /* core dumps don't get here */
854 if (current->signal->group_exit)
855 exit_code = current->signal->group_exit_code;
856 else if (!thread_group_empty(current)) {
857 struct signal_struct *const sig = current->signal;
858 struct sighand_struct *const sighand = current->sighand;
859 read_lock(&tasklist_lock);
860 spin_lock_irq(&sighand->siglock);
862 /* Another thread got here before we took the lock. */
863 exit_code = sig->group_exit_code;
866 sig->group_exit_code = exit_code;
867 zap_other_threads(current);
869 spin_unlock_irq(&sighand->siglock);
870 read_unlock(&tasklist_lock);
878 * this kills every thread in the thread group. Note that any externally
879 * wait4()-ing process will get the correct exit code - even if this
880 * thread is not the thread group leader.
882 asmlinkage void sys_exit_group(int error_code)
884 do_group_exit((error_code & 0xff) << 8);
887 static int eligible_child(pid_t pid, int options, task_t *p)
893 if (process_group(p) != process_group(current))
895 } else if (pid != -1) {
896 if (process_group(p) != -pid)
901 * Do not consider detached threads that are
904 if (p->exit_signal == -1 && !p->ptrace)
907 /* Wait for all children (clone and not) if __WALL is set;
908 * otherwise, wait for clone children *only* if __WCLONE is
909 * set; otherwise, wait for non-clone children *only*. (Note:
910 * A "clone" child here is one that reports to its parent
911 * using a signal other than SIGCHLD.) */
912 if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
913 && !(options & __WALL))
916 * Do not consider thread group leaders that are
917 * in a non-empty thread group:
919 if (current->tgid != p->tgid && delay_group_leader(p))
922 if (security_task_wait(p))
929 * Handle sys_wait4 work for one task in state TASK_ZOMBIE. We hold
930 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
931 * the lock and this task is uninteresting. If we return nonzero, we have
932 * released the lock and the system call should return.
934 static int wait_task_zombie(task_t *p, unsigned int *stat_addr, struct rusage *ru)
940 * Try to move the task's state to DEAD
941 * only one thread is allowed to do this:
943 state = xchg(&p->state, TASK_DEAD);
944 if (state != TASK_ZOMBIE) {
945 BUG_ON(state != TASK_DEAD);
948 if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
950 * This can only happen in a race with a ptraced thread
951 * dying on another processor.
956 * Now we are sure this task is interesting, and no other
957 * thread can reap it because we set its state to TASK_DEAD.
959 read_unlock(&tasklist_lock);
961 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
962 if (!retval && stat_addr) {
963 if (p->signal->group_exit)
964 retval = put_user(p->signal->group_exit_code, stat_addr);
966 retval = put_user(p->exit_code, stat_addr);
969 p->state = TASK_ZOMBIE;
973 if (p->real_parent != p->parent) {
974 write_lock_irq(&tasklist_lock);
975 /* Double-check with lock held. */
976 if (p->real_parent != p->parent) {
978 p->state = TASK_ZOMBIE;
979 /* If this is a detached thread, this is where it goes away. */
980 if (p->exit_signal == -1) {
981 /* release_task takes the lock itself. */
982 write_unlock_irq(&tasklist_lock);
986 do_notify_parent(p, p->exit_signal);
987 write_unlock_irq(&tasklist_lock);
992 write_unlock_irq(&tasklist_lock);
1001 * Handle sys_wait4 work for one task in state TASK_STOPPED. We hold
1002 * read_lock(&tasklist_lock) on entry. If we return zero, we still hold
1003 * the lock and this task is uninteresting. If we return nonzero, we have
1004 * released the lock and the system call should return.
1006 static int wait_task_stopped(task_t *p, int delayed_group_leader,
1007 unsigned int *stat_addr, struct rusage *ru)
1009 int retval, exit_code;
1013 if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
1014 p->signal && p->signal->group_stop_count > 0)
1016 * A group stop is in progress and this is the group leader.
1017 * We won't report until all threads have stopped.
1022 * Now we are pretty sure this task is interesting.
1023 * Make sure it doesn't get reaped out from under us while we
1024 * give up the lock and then examine it below. We don't want to
1025 * keep holding onto the tasklist_lock while we call getrusage and
1026 * possibly take page faults for user memory.
1029 read_unlock(&tasklist_lock);
1030 write_lock_irq(&tasklist_lock);
1033 * This uses xchg to be atomic with the thread resuming and setting
1034 * it. It must also be done with the write lock held to prevent a
1035 * race with the TASK_ZOMBIE case.
1037 exit_code = xchg(&p->exit_code, 0);
1038 if (unlikely(p->state > TASK_STOPPED)) {
1040 * The task resumed and then died. Let the next iteration
1041 * catch it in TASK_ZOMBIE. Note that exit_code might
1042 * already be zero here if it resumed and did _exit(0).
1043 * The task itself is dead and won't touch exit_code again;
1044 * other processors in this function are locked out.
1046 p->exit_code = exit_code;
1049 if (unlikely(exit_code == 0)) {
1051 * Another thread in this function got to it first, or it
1052 * resumed, or it resumed and then died.
1054 write_unlock_irq(&tasklist_lock);
1056 read_lock(&tasklist_lock);
1060 /* move to end of parent's list to avoid starvation */
1062 add_parent(p, p->parent);
1064 write_unlock_irq(&tasklist_lock);
1066 retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
1067 if (!retval && stat_addr)
1068 retval = put_user((exit_code << 8) | 0x7f, stat_addr);
1077 asmlinkage long sys_wait4(pid_t pid,unsigned int * stat_addr, int options, struct rusage * ru)
1079 DECLARE_WAITQUEUE(wait, current);
1080 struct task_struct *tsk;
1083 if (options & ~(WNOHANG|WUNTRACED|__WNOTHREAD|__WCLONE|__WALL))
1086 add_wait_queue(¤t->wait_chldexit,&wait);
1089 current->state = TASK_INTERRUPTIBLE;
1090 read_lock(&tasklist_lock);
1093 struct task_struct *p;
1094 struct list_head *_p;
1097 list_for_each(_p,&tsk->children) {
1098 p = list_entry(_p,struct task_struct,sibling);
1100 ret = eligible_child(pid, options, p);
1107 if (!(options & WUNTRACED) &&
1108 !(p->ptrace & PT_PTRACED))
1110 retval = wait_task_stopped(p, ret == 2,
1112 if (retval != 0) /* He released the lock. */
1117 * Eligible but we cannot release it yet:
1121 retval = wait_task_zombie(p, stat_addr, ru);
1122 if (retval != 0) /* He released the lock. */
1128 list_for_each (_p,&tsk->ptrace_children) {
1129 p = list_entry(_p,struct task_struct,ptrace_list);
1130 if (!eligible_child(pid, options, p))
1136 if (options & __WNOTHREAD)
1138 tsk = next_thread(tsk);
1139 if (tsk->signal != current->signal)
1141 } while (tsk != current);
1142 read_unlock(&tasklist_lock);
1145 if (options & WNOHANG)
1147 retval = -ERESTARTSYS;
1148 if (signal_pending(current))
1155 current->state = TASK_RUNNING;
1156 remove_wait_queue(¤t->wait_chldexit,&wait);
1160 #if !defined(__alpha__) && !defined(__ia64__) && \
1161 !defined(__arm__) && !defined(__s390__)
1164 * sys_waitpid() remains for compatibility. waitpid() should be
1165 * implemented by calling sys_wait4() from libc.a.
1167 asmlinkage long sys_waitpid(pid_t pid,unsigned int * stat_addr, int options)
1169 return sys_wait4(pid, stat_addr, options, NULL);