/*
   *  linux/kernel/exit.c
   *
   *  Copyright (C) 1991, 1992  Linus Torvalds
   */

  #include <linux/mm.h>
  #include <linux/slab.h>
  #include <linux/interrupt.h>
  #include <linux/smp_lock.h>
  #include <linux/module.h>

  #include <linux/capability.h>

  #include <linux/completion.h>
  #include <linux/personality.h>
  #include <linux/tty.h>
  #include <linux/namespace.h>
  #include <linux/key.h>
  #include <linux/security.h>
  #include <linux/cpu.h>
  #include <linux/acct.h>
  #include <linux/file.h>
  #include <linux/binfmts.h>
  #include <linux/ptrace.h>
  #include <linux/profile.h>
  #include <linux/mount.h>
  #include <linux/proc_fs.h>
  #include <linux/mempolicy.h>

  #include <linux/taskstats_kern.h>

  #include <linux/delayacct.h>

  #include <linux/cpuset.h>
  #include <linux/syscalls.h>

  #include <linux/signal.h>

  #include <linux/posix-timers.h>

  #include <linux/cn_proc.h>

  #include <linux/mutex.h>

  #include <linux/futex.h>

  #include <linux/compat.h>

  #include <linux/pipe_fs_i.h>

  #include <linux/audit.h> /* for audit_free() */

  #include <linux/resource.h>

  
  #include <asm/uaccess.h>
  #include <asm/unistd.h>
  #include <asm/pgtable.h>
  #include <asm/mmu_context.h>
  
  extern void sem_exit (void);
  extern struct task_struct *child_reaper;

  static void exit_mm(struct task_struct * tsk);

  static void __unhash_process(struct task_struct *p)
  {
  	nr_threads--;
  	detach_pid(p, PIDTYPE_PID);

  	if (thread_group_leader(p)) {
  		detach_pid(p, PIDTYPE_PGID);
  		detach_pid(p, PIDTYPE_SID);

  		list_del_rcu(&p->tasks);

  		__get_cpu_var(process_counts)--;

  	}

  	list_del_rcu(&p->thread_group);

  	remove_parent(p);

  }

  /*
   * This function expects the tasklist_lock write-locked.
   */
  static void __exit_signal(struct task_struct *tsk)
  {
  	struct signal_struct *sig = tsk->signal;
  	struct sighand_struct *sighand;
  
  	BUG_ON(!sig);
  	BUG_ON(!atomic_read(&sig->count));
  
  	rcu_read_lock();
  	sighand = rcu_dereference(tsk->sighand);
  	spin_lock(&sighand->siglock);
  
  	posix_cpu_timers_exit(tsk);
  	if (atomic_dec_and_test(&sig->count))
  		posix_cpu_timers_exit_group(tsk);
  	else {
  		/*
  		 * If there is any task waiting for the group exit
  		 * then notify it:
  		 */
  		if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count) {
  			wake_up_process(sig->group_exit_task);
  			sig->group_exit_task = NULL;
  		}
  		if (tsk == sig->curr_target)
  			sig->curr_target = next_thread(tsk);
  		/*
  		 * Accumulate here the counters for all threads but the
  		 * group leader as they die, so they can be added into
  		 * the process-wide totals when those are taken.
  		 * The group leader stays around as a zombie as long
  		 * as there are other threads.  When it gets reaped,
  		 * the exit.c code will add its counts into these totals.
  		 * We won't ever get here for the group leader, since it
  		 * will have been the last reference on the signal_struct.
  		 */
  		sig->utime = cputime_add(sig->utime, tsk->utime);
  		sig->stime = cputime_add(sig->stime, tsk->stime);
  		sig->min_flt += tsk->min_flt;
  		sig->maj_flt += tsk->maj_flt;
  		sig->nvcsw += tsk->nvcsw;
  		sig->nivcsw += tsk->nivcsw;
  		sig->sched_time += tsk->sched_time;
  		sig = NULL; /* Marker for below. */
  	}

  	__unhash_process(tsk);

  	tsk->signal = NULL;

  	tsk->sighand = NULL;

  	spin_unlock(&sighand->siglock);
  	rcu_read_unlock();

  	__cleanup_sighand(sighand);

  	clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
  	flush_sigqueue(&tsk->pending);
  	if (sig) {
  		flush_sigqueue(&sig->shared_pending);
  		__cleanup_signal(sig);
  	}
  }

  static void delayed_put_task_struct(struct rcu_head *rhp)
  {
  	put_task_struct(container_of(rhp, struct task_struct, rcu));
  }

  void release_task(struct task_struct * p)
  {

  	struct task_struct *leader;

  	int zap_leader;

  repeat:

  	atomic_dec(&p->user->processes);

  	write_lock_irq(&tasklist_lock);

  	ptrace_unlink(p);

  	BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
  	__exit_signal(p);

  	/*
  	 * If we are the last non-leader member of the thread
  	 * group, and the leader is zombie, then notify the
  	 * group leader's parent process. (if it wants notification.)
  	 */
  	zap_leader = 0;
  	leader = p->group_leader;
  	if (leader != p && thread_group_empty(leader) && leader->exit_state == EXIT_ZOMBIE) {
  		BUG_ON(leader->exit_signal == -1);
  		do_notify_parent(leader, leader->exit_signal);
  		/*
  		 * If we were the last child thread and the leader has
  		 * exited already, and the leader's parent ignores SIGCHLD,
  		 * then we are the one who should release the leader.
  		 *
  		 * do_notify_parent() will have marked it self-reaping in
  		 * that case.
  		 */
  		zap_leader = (leader->exit_signal == -1);
  	}
  
  	sched_exit(p);
  	write_unlock_irq(&tasklist_lock);

  	proc_flush_task(p);

  	release_thread(p);

  	call_rcu(&p->rcu, delayed_put_task_struct);

  
  	p = leader;
  	if (unlikely(zap_leader))
  		goto repeat;
  }

  /*
   * This checks not only the pgrp, but falls back on the pid if no
   * satisfactory pgrp is found. I dunno - gdb doesn't work correctly
   * without this...
   */
  int session_of_pgrp(int pgrp)
  {
  	struct task_struct *p;
  	int sid = -1;
  
  	read_lock(&tasklist_lock);
  	do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
  		if (p->signal->session > 0) {
  			sid = p->signal->session;
  			goto out;
  		}
  	} while_each_task_pid(pgrp, PIDTYPE_PGID, p);
  	p = find_task_by_pid(pgrp);
  	if (p)
  		sid = p->signal->session;
  out:
  	read_unlock(&tasklist_lock);
  	
  	return sid;
  }
  
  /*
   * Determine if a process group is "orphaned", according to the POSIX
   * definition in 2.2.2.52.  Orphaned process groups are not to be affected
   * by terminal-generated stop signals.  Newly orphaned process groups are
   * to receive a SIGHUP and a SIGCONT.
   *
   * "I ask you, have you ever known what it is to be an orphan?"
   */

  static int will_become_orphaned_pgrp(int pgrp, struct task_struct *ignored_task)

  {
  	struct task_struct *p;
  	int ret = 1;
  
  	do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
  		if (p == ignored_task
  				|| p->exit_state
  				|| p->real_parent->pid == 1)
  			continue;
  		if (process_group(p->real_parent) != pgrp
  			    && p->real_parent->signal->session == p->signal->session) {
  			ret = 0;
  			break;
  		}
  	} while_each_task_pid(pgrp, PIDTYPE_PGID, p);
  	return ret;	/* (sighing) "Often!" */
  }
  
  int is_orphaned_pgrp(int pgrp)
  {
  	int retval;
  
  	read_lock(&tasklist_lock);
  	retval = will_become_orphaned_pgrp(pgrp, NULL);
  	read_unlock(&tasklist_lock);
  
  	return retval;
  }

  static int has_stopped_jobs(int pgrp)

  {
  	int retval = 0;
  	struct task_struct *p;
  
  	do_each_task_pid(pgrp, PIDTYPE_PGID, p) {
  		if (p->state != TASK_STOPPED)
  			continue;
  
  		/* If p is stopped by a debugger on a signal that won't
  		   stop it, then don't count p as stopped.  This isn't
  		   perfect but it's a good approximation.  */
  		if (unlikely (p->ptrace)
  		    && p->exit_code != SIGSTOP
  		    && p->exit_code != SIGTSTP
  		    && p->exit_code != SIGTTOU
  		    && p->exit_code != SIGTTIN)
  			continue;
  
  		retval = 1;
  		break;
  	} while_each_task_pid(pgrp, PIDTYPE_PGID, p);
  	return retval;
  }
  
  /**

   * reparent_to_init - Reparent the calling kernel thread to the init task.

   *
   * If a kernel thread is launched as a result of a system call, or if
   * it ever exits, it should generally reparent itself to init so that
   * it is correctly cleaned up on exit.
   *
   * The various task state such as scheduling policy and priority may have
   * been inherited from a user process, so we reset them to sane values here.
   *
   * NOTE that reparent_to_init() gives the caller full capabilities.
   */

  static void reparent_to_init(void)

  {
  	write_lock_irq(&tasklist_lock);
  
  	ptrace_unlink(current);
  	/* Reparent to init */

  	remove_parent(current);

  	current->parent = child_reaper;
  	current->real_parent = child_reaper;

  	add_parent(current);

  
  	/* Set the exit signal to SIGCHLD so we signal init on exit */
  	current->exit_signal = SIGCHLD;

  	if ((current->policy == SCHED_NORMAL ||
  			current->policy == SCHED_BATCH)
  				&& (task_nice(current) < 0))

  		set_user_nice(current, 0);
  	/* cpus_allowed? */
  	/* rt_priority? */
  	/* signals? */
  	security_task_reparent_to_init(current);
  	memcpy(current->signal->rlim, init_task.signal->rlim,
  	       sizeof(current->signal->rlim));
  	atomic_inc(&(INIT_USER->__count));
  	write_unlock_irq(&tasklist_lock);
  	switch_uid(INIT_USER);
  }
  
  void __set_special_pids(pid_t session, pid_t pgrp)
  {

  	struct task_struct *curr = current->group_leader;

  
  	if (curr->signal->session != session) {
  		detach_pid(curr, PIDTYPE_SID);
  		curr->signal->session = session;
  		attach_pid(curr, PIDTYPE_SID, session);
  	}
  	if (process_group(curr) != pgrp) {
  		detach_pid(curr, PIDTYPE_PGID);
  		curr->signal->pgrp = pgrp;
  		attach_pid(curr, PIDTYPE_PGID, pgrp);
  	}
  }
  
  void set_special_pids(pid_t session, pid_t pgrp)
  {
  	write_lock_irq(&tasklist_lock);
  	__set_special_pids(session, pgrp);
  	write_unlock_irq(&tasklist_lock);
  }
  
  /*
   * Let kernel threads use this to say that they
   * allow a certain signal (since daemonize() will
   * have disabled all of them by default).
   */
  int allow_signal(int sig)
  {

  	if (!valid_signal(sig) || sig < 1)

  		return -EINVAL;
  
  	spin_lock_irq(&current->sighand->siglock);
  	sigdelset(&current->blocked, sig);
  	if (!current->mm) {
  		/* Kernel threads handle their own signals.
  		   Let the signal code know it'll be handled, so
  		   that they don't get converted to SIGKILL or
  		   just silently dropped */
  		current->sighand->action[(sig)-1].sa.sa_handler = (void __user *)2;
  	}
  	recalc_sigpending();
  	spin_unlock_irq(&current->sighand->siglock);
  	return 0;
  }
  
  EXPORT_SYMBOL(allow_signal);
  
  int disallow_signal(int sig)
  {

  	if (!valid_signal(sig) || sig < 1)

  		return -EINVAL;
  
  	spin_lock_irq(&current->sighand->siglock);
  	sigaddset(&current->blocked, sig);
  	recalc_sigpending();
  	spin_unlock_irq(&current->sighand->siglock);
  	return 0;
  }
  
  EXPORT_SYMBOL(disallow_signal);
  
  /*
   *	Put all the gunge required to become a kernel thread without
   *	attached user resources in one place where it belongs.
   */
  
  void daemonize(const char *name, ...)
  {
  	va_list args;
  	struct fs_struct *fs;
  	sigset_t blocked;
  
  	va_start(args, name);
  	vsnprintf(current->comm, sizeof(current->comm), name, args);
  	va_end(args);
  
  	/*
  	 * If we were started as result of loading a module, close all of the
  	 * user space pages.  We don't need them, and if we didn't close them
  	 * they would be locked into memory.
  	 */
  	exit_mm(current);
  
  	set_special_pids(1, 1);

  	mutex_lock(&tty_mutex);

  	current->signal->tty = NULL;

  	mutex_unlock(&tty_mutex);

  
  	/* Block and flush all signals */
  	sigfillset(&blocked);
  	sigprocmask(SIG_BLOCK, &blocked, NULL);
  	flush_signals(current);
  
  	/* Become as one with the init task */
  
  	exit_fs(current);	/* current->fs->count--; */
  	fs = init_task.fs;
  	current->fs = fs;
  	atomic_inc(&fs->count);

  	exit_namespace(current);
  	current->namespace = init_task.namespace;
  	get_namespace(current->namespace);

   	exit_files(current);
  	current->files = init_task.files;
  	atomic_inc(&current->files->count);
  
  	reparent_to_init();
  }
  
  EXPORT_SYMBOL(daemonize);

  static void close_files(struct files_struct * files)

  {
  	int i, j;

  	struct fdtable *fdt;

  
  	j = 0;

  
  	/*
  	 * It is safe to dereference the fd table without RCU or
  	 * ->file_lock because this is the last reference to the
  	 * files structure.
  	 */

  	fdt = files_fdtable(files);

  	for (;;) {
  		unsigned long set;
  		i = j * __NFDBITS;

  		if (i >= fdt->max_fdset || i >= fdt->max_fds)

  			break;

  		set = fdt->open_fds->fds_bits[j++];

  		while (set) {
  			if (set & 1) {

  				struct file * file = xchg(&fdt->fd[i], NULL);

  				if (file)
  					filp_close(file, files);
  			}
  			i++;
  			set >>= 1;
  		}
  	}
  }
  
  struct files_struct *get_files_struct(struct task_struct *task)
  {
  	struct files_struct *files;
  
  	task_lock(task);
  	files = task->files;
  	if (files)
  		atomic_inc(&files->count);
  	task_unlock(task);
  
  	return files;
  }
  
  void fastcall put_files_struct(struct files_struct *files)
  {

  	struct fdtable *fdt;

  	if (atomic_dec_and_test(&files->count)) {
  		close_files(files);
  		/*
  		 * Free the fd and fdset arrays if we expanded them.

  		 * If the fdtable was embedded, pass files for freeing
  		 * at the end of the RCU grace period. Otherwise,
  		 * you can free files immediately.

  		 */

  		fdt = files_fdtable(files);

  		if (fdt == &files->fdtab)
  			fdt->free_files = files;
  		else
  			kmem_cache_free(files_cachep, files);
  		free_fdtable(fdt);

  	}
  }
  
  EXPORT_SYMBOL(put_files_struct);
  
  static inline void __exit_files(struct task_struct *tsk)
  {
  	struct files_struct * files = tsk->files;
  
  	if (files) {
  		task_lock(tsk);
  		tsk->files = NULL;
  		task_unlock(tsk);
  		put_files_struct(files);
  	}
  }
  
  void exit_files(struct task_struct *tsk)
  {
  	__exit_files(tsk);
  }
  
  static inline void __put_fs_struct(struct fs_struct *fs)
  {
  	/* No need to hold fs->lock if we are killing it */
  	if (atomic_dec_and_test(&fs->count)) {
  		dput(fs->root);
  		mntput(fs->rootmnt);
  		dput(fs->pwd);
  		mntput(fs->pwdmnt);
  		if (fs->altroot) {
  			dput(fs->altroot);
  			mntput(fs->altrootmnt);
  		}
  		kmem_cache_free(fs_cachep, fs);
  	}
  }
  
  void put_fs_struct(struct fs_struct *fs)
  {
  	__put_fs_struct(fs);
  }
  
  static inline void __exit_fs(struct task_struct *tsk)
  {
  	struct fs_struct * fs = tsk->fs;
  
  	if (fs) {
  		task_lock(tsk);
  		tsk->fs = NULL;
  		task_unlock(tsk);
  		__put_fs_struct(fs);
  	}
  }
  
  void exit_fs(struct task_struct *tsk)
  {
  	__exit_fs(tsk);
  }
  
  EXPORT_SYMBOL_GPL(exit_fs);
  
  /*
   * Turn us into a lazy TLB process if we
   * aren't already..
   */

  static void exit_mm(struct task_struct * tsk)

  {
  	struct mm_struct *mm = tsk->mm;
  
  	mm_release(tsk, mm);
  	if (!mm)
  		return;
  	/*
  	 * Serialize with any possible pending coredump.
  	 * We must hold mmap_sem around checking core_waiters
  	 * and clearing tsk->mm.  The core-inducing thread
  	 * will increment core_waiters for each thread in the
  	 * group with ->mm != NULL.
  	 */
  	down_read(&mm->mmap_sem);
  	if (mm->core_waiters) {
  		up_read(&mm->mmap_sem);
  		down_write(&mm->mmap_sem);
  		if (!--mm->core_waiters)
  			complete(mm->core_startup_done);
  		up_write(&mm->mmap_sem);
  
  		wait_for_completion(&mm->core_done);
  		down_read(&mm->mmap_sem);
  	}
  	atomic_inc(&mm->mm_count);

  	BUG_ON(mm != tsk->active_mm);

  	/* more a memory barrier than a real lock */
  	task_lock(tsk);
  	tsk->mm = NULL;
  	up_read(&mm->mmap_sem);
  	enter_lazy_tlb(mm, current);
  	task_unlock(tsk);
  	mmput(mm);
  }

  static inline void
  choose_new_parent(struct task_struct *p, struct task_struct *reaper)

  {
  	/*
  	 * Make sure we're not reparenting to ourselves and that
  	 * the parent is not a zombie.
  	 */

  	BUG_ON(p == reaper || reaper->exit_state);

  	p->real_parent = reaper;

  }

  static void
  reparent_thread(struct task_struct *p, struct task_struct *father, int traced)

  {
  	/* We don't want people slaying init.  */
  	if (p->exit_signal != -1)
  		p->exit_signal = SIGCHLD;
  
  	if (p->pdeath_signal)
  		/* We already hold the tasklist_lock here.  */

  		group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);

  
  	/* Move the child from its dying parent to the new one.  */
  	if (unlikely(traced)) {
  		/* Preserve ptrace links if someone else is tracing this child.  */
  		list_del_init(&p->ptrace_list);
  		if (p->parent != p->real_parent)
  			list_add(&p->ptrace_list, &p->real_parent->ptrace_children);
  	} else {
  		/* If this child is being traced, then we're the one tracing it
  		 * anyway, so let go of it.
  		 */
  		p->ptrace = 0;

  		remove_parent(p);

  		p->parent = p->real_parent;

  		add_parent(p);

  
  		/* If we'd notified the old parent about this child's death,
  		 * also notify the new parent.
  		 */
  		if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
  		    thread_group_empty(p))
  			do_notify_parent(p, p->exit_signal);
  		else if (p->state == TASK_TRACED) {
  			/*
  			 * If it was at a trace stop, turn it into
  			 * a normal stop since it's no longer being
  			 * traced.
  			 */
  			ptrace_untrace(p);
  		}
  	}
  
  	/*
  	 * process group orphan check
  	 * Case ii: Our child is in a different pgrp
  	 * than we are, and it was the only connection
  	 * outside, so the child pgrp is now orphaned.
  	 */
  	if ((process_group(p) != process_group(father)) &&
  	    (p->signal->session == father->signal->session)) {
  		int pgrp = process_group(p);
  
  		if (will_become_orphaned_pgrp(pgrp, NULL) && has_stopped_jobs(pgrp)) {

  			__kill_pg_info(SIGHUP, SEND_SIG_PRIV, pgrp);
  			__kill_pg_info(SIGCONT, SEND_SIG_PRIV, pgrp);

  		}
  	}
  }
  
  /*
   * When we die, we re-parent all our children.
   * Try to give them to another thread in our thread
   * group, and if no such member exists, give it to
   * the global child reaper process (ie "init")
   */

  static void
  forget_original_parent(struct task_struct *father, struct list_head *to_release)

  {
  	struct task_struct *p, *reaper = father;
  	struct list_head *_p, *_n;
  
  	do {
  		reaper = next_thread(reaper);
  		if (reaper == father) {
  			reaper = child_reaper;
  			break;
  		}
  	} while (reaper->exit_state);
  
  	/*
  	 * There are only two places where our children can be:
  	 *
  	 * - in our child list
  	 * - in our ptraced child list
  	 *
  	 * Search them and reparent children.
  	 */
  	list_for_each_safe(_p, _n, &father->children) {
  		int ptrace;

  		p = list_entry(_p, struct task_struct, sibling);

  
  		ptrace = p->ptrace;
  
  		/* if father isn't the real parent, then ptrace must be enabled */
  		BUG_ON(father != p->real_parent && !ptrace);
  
  		if (father == p->real_parent) {
  			/* reparent with a reaper, real father it's us */

  			choose_new_parent(p, reaper);

  			reparent_thread(p, father, 0);
  		} else {
  			/* reparent ptraced task to its real parent */
  			__ptrace_unlink (p);
  			if (p->exit_state == EXIT_ZOMBIE && p->exit_signal != -1 &&
  			    thread_group_empty(p))
  				do_notify_parent(p, p->exit_signal);
  		}
  
  		/*
  		 * if the ptraced child is a zombie with exit_signal == -1
  		 * we must collect it before we exit, or it will remain
  		 * zombie forever since we prevented it from self-reap itself
  		 * while it was being traced by us, to be able to see it in wait4.
  		 */
  		if (unlikely(ptrace && p->exit_state == EXIT_ZOMBIE && p->exit_signal == -1))
  			list_add(&p->ptrace_list, to_release);
  	}
  	list_for_each_safe(_p, _n, &father->ptrace_children) {

  		p = list_entry(_p, struct task_struct, ptrace_list);

  		choose_new_parent(p, reaper);

  		reparent_thread(p, father, 1);
  	}
  }
  
  /*
   * Send signals to all our closest relatives so that they know
   * to properly mourn us..
   */
  static void exit_notify(struct task_struct *tsk)
  {
  	int state;
  	struct task_struct *t;
  	struct list_head ptrace_dead, *_p, *_n;
  
  	if (signal_pending(tsk) && !(tsk->signal->flags & SIGNAL_GROUP_EXIT)
  	    && !thread_group_empty(tsk)) {
  		/*
  		 * This occurs when there was a race between our exit
  		 * syscall and a group signal choosing us as the one to
  		 * wake up.  It could be that we are the only thread
  		 * alerted to check for pending signals, but another thread
  		 * should be woken now to take the signal since we will not.
  		 * Now we'll wake all the threads in the group just to make
  		 * sure someone gets all the pending signals.
  		 */
  		read_lock(&tasklist_lock);
  		spin_lock_irq(&tsk->sighand->siglock);
  		for (t = next_thread(tsk); t != tsk; t = next_thread(t))
  			if (!signal_pending(t) && !(t->flags & PF_EXITING)) {
  				recalc_sigpending_tsk(t);
  				if (signal_pending(t))
  					signal_wake_up(t, 0);
  			}
  		spin_unlock_irq(&tsk->sighand->siglock);
  		read_unlock(&tasklist_lock);
  	}
  
  	write_lock_irq(&tasklist_lock);
  
  	/*
  	 * This does two things:
  	 *
    	 * A.  Make init inherit all the child processes
  	 * B.  Check to see if any process groups have become orphaned
  	 *	as a result of our exiting, and if they have any stopped
  	 *	jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
  	 */
  
  	INIT_LIST_HEAD(&ptrace_dead);
  	forget_original_parent(tsk, &ptrace_dead);
  	BUG_ON(!list_empty(&tsk->children));
  	BUG_ON(!list_empty(&tsk->ptrace_children));
  
  	/*
  	 * Check to see if any process groups have become orphaned
  	 * as a result of our exiting, and if they have any stopped
  	 * jobs, send them a SIGHUP and then a SIGCONT.  (POSIX 3.2.2.2)
  	 *
  	 * Case i: Our father is in a different pgrp than we are
  	 * and we were the only connection outside, so our pgrp
  	 * is about to become orphaned.
  	 */
  	 
  	t = tsk->real_parent;
  	
  	if ((process_group(t) != process_group(tsk)) &&
  	    (t->signal->session == tsk->signal->session) &&
  	    will_become_orphaned_pgrp(process_group(tsk), tsk) &&
  	    has_stopped_jobs(process_group(tsk))) {

  		__kill_pg_info(SIGHUP, SEND_SIG_PRIV, process_group(tsk));
  		__kill_pg_info(SIGCONT, SEND_SIG_PRIV, process_group(tsk));

  	}
  
  	/* Let father know we died 
  	 *
  	 * Thread signals are configurable, but you aren't going to use
  	 * that to send signals to arbitary processes. 
  	 * That stops right now.
  	 *
  	 * If the parent exec id doesn't match the exec id we saved
  	 * when we started then we know the parent has changed security
  	 * domain.
  	 *
  	 * If our self_exec id doesn't match our parent_exec_id then
  	 * we have changed execution domain as these two values started
  	 * the same after a fork.
  	 *	
  	 */
  	
  	if (tsk->exit_signal != SIGCHLD && tsk->exit_signal != -1 &&
  	    ( tsk->parent_exec_id != t->self_exec_id  ||
  	      tsk->self_exec_id != tsk->parent_exec_id)
  	    && !capable(CAP_KILL))
  		tsk->exit_signal = SIGCHLD;
  
  
  	/* If something other than our normal parent is ptracing us, then
  	 * send it a SIGCHLD instead of honoring exit_signal.  exit_signal
  	 * only has special meaning to our real parent.
  	 */
  	if (tsk->exit_signal != -1 && thread_group_empty(tsk)) {
  		int signal = tsk->parent == tsk->real_parent ? tsk->exit_signal : SIGCHLD;
  		do_notify_parent(tsk, signal);
  	} else if (tsk->ptrace) {
  		do_notify_parent(tsk, SIGCHLD);
  	}
  
  	state = EXIT_ZOMBIE;
  	if (tsk->exit_signal == -1 &&
  	    (likely(tsk->ptrace == 0) ||
  	     unlikely(tsk->parent->signal->flags & SIGNAL_GROUP_EXIT)))
  		state = EXIT_DEAD;
  	tsk->exit_state = state;
  
  	write_unlock_irq(&tasklist_lock);
  
  	list_for_each_safe(_p, _n, &ptrace_dead) {
  		list_del_init(_p);

  		t = list_entry(_p, struct task_struct, ptrace_list);

  		release_task(t);
  	}
  
  	/* If the process is dead, release it - nobody will wait for it */
  	if (state == EXIT_DEAD)
  		release_task(tsk);

  }
  
  fastcall NORET_TYPE void do_exit(long code)
  {
  	struct task_struct *tsk = current;

  	struct taskstats *tidstats;

  	int group_dead;

  	unsigned int mycpu;

  
  	profile_task_exit(tsk);

  	WARN_ON(atomic_read(&tsk->fs_excl));

  	if (unlikely(in_interrupt()))
  		panic("Aiee, killing interrupt handler!");
  	if (unlikely(!tsk->pid))
  		panic("Attempted to kill the idle task!");

  	if (unlikely(tsk == child_reaper))

  		panic("Attempted to kill init!");

  
  	if (unlikely(current->ptrace & PT_TRACE_EXIT)) {
  		current->ptrace_message = code;
  		ptrace_notify((PTRACE_EVENT_EXIT << 8) | SIGTRAP);
  	}

  	/*
  	 * We're taking recursive faults here in do_exit. Safest is to just
  	 * leave this task alone and wait for reboot.
  	 */
  	if (unlikely(tsk->flags & PF_EXITING)) {
  		printk(KERN_ALERT
  			"Fixing recursive fault but reboot is needed!
  ");

  		if (tsk->io_context)
  			exit_io_context();

  		set_current_state(TASK_UNINTERRUPTIBLE);
  		schedule();
  	}

  	tsk->flags |= PF_EXITING;

  	if (unlikely(in_atomic()))
  		printk(KERN_INFO "note: %s[%d] exited with preempt_count %d
  ",
  				current->comm, current->pid,
  				preempt_count());

  	taskstats_exit_alloc(&tidstats, &mycpu);

  	acct_update_integrals(tsk);

  	if (tsk->mm) {
  		update_hiwater_rss(tsk->mm);
  		update_hiwater_vm(tsk->mm);
  	}

  	group_dead = atomic_dec_and_test(&tsk->signal->live);

  	if (group_dead) {

   		hrtimer_cancel(&tsk->signal->real_timer);

  		exit_itimers(tsk->signal);

  	}

  	acct_collect(code, group_dead);

  	if (unlikely(tsk->robust_list))
  		exit_robust_list(tsk);

  #if defined(CONFIG_FUTEX) && defined(CONFIG_COMPAT)

  	if (unlikely(tsk->compat_robust_list))
  		compat_exit_robust_list(tsk);
  #endif

  	if (unlikely(tsk->audit_context))
  		audit_free(tsk);

  	taskstats_exit_send(tsk, tidstats, group_dead, mycpu);

  	taskstats_exit_free(tidstats);

  	exit_mm(tsk);

  	if (group_dead)

  		acct_process();

  	exit_sem(tsk);
  	__exit_files(tsk);
  	__exit_fs(tsk);
  	exit_namespace(tsk);
  	exit_thread();
  	cpuset_exit(tsk);
  	exit_keys(tsk);
  
  	if (group_dead && tsk->signal->leader)
  		disassociate_ctty(1);

  	module_put(task_thread_info(tsk)->exec_domain->module);

  	if (tsk->binfmt)
  		module_put(tsk->binfmt->module);
  
  	tsk->exit_code = code;

  	proc_exit_connector(tsk);

  	exit_notify(tsk);
  #ifdef CONFIG_NUMA
  	mpol_free(tsk->mempolicy);
  	tsk->mempolicy = NULL;
  #endif

  	/*

  	 * This must happen late, after the PID is not
  	 * hashed anymore:
  	 */
  	if (unlikely(!list_empty(&tsk->pi_state_list)))
  		exit_pi_state_list(tsk);
  	if (unlikely(current->pi_state_cache))
  		kfree(current->pi_state_cache);
  	/*

  	 * Make sure we are holding no locks:

  	 */

  	debug_check_no_locks_held(tsk);

  	if (tsk->io_context)
  		exit_io_context();

  	if (tsk->splice_pipe)
  		__free_pipe_info(tsk->splice_pipe);

  	/* PF_DEAD causes final put_task_struct after we schedule. */
  	preempt_disable();
  	BUG_ON(tsk->flags & PF_DEAD);
  	tsk->flags |= PF_DEAD;

  	schedule();
  	BUG();
  	/* Avoid "noreturn function does return".  */
  	for (;;) ;
  }

  EXPORT_SYMBOL_GPL(do_exit);

  NORET_TYPE void complete_and_exit(struct completion *comp, long code)
  {
  	if (comp)
  		complete(comp);
  	
  	do_exit(code);
  }
  
  EXPORT_SYMBOL(complete_and_exit);
  
  asmlinkage long sys_exit(int error_code)
  {
  	do_exit((error_code&0xff)<<8);
  }

  /*
   * Take down every thread in the group.  This is called by fatal signals
   * as well as by sys_exit_group (below).
   */
  NORET_TYPE void
  do_group_exit(int exit_code)
  {
  	BUG_ON(exit_code & 0x80); /* core dumps don't get here */
  
  	if (current->signal->flags & SIGNAL_GROUP_EXIT)
  		exit_code = current->signal->group_exit_code;
  	else if (!thread_group_empty(current)) {
  		struct signal_struct *const sig = current->signal;
  		struct sighand_struct *const sighand = current->sighand;

  		spin_lock_irq(&sighand->siglock);
  		if (sig->flags & SIGNAL_GROUP_EXIT)
  			/* Another thread got here before we took the lock.  */
  			exit_code = sig->group_exit_code;
  		else {

  			sig->group_exit_code = exit_code;
  			zap_other_threads(current);
  		}
  		spin_unlock_irq(&sighand->siglock);

  	}
  
  	do_exit(exit_code);
  	/* NOTREACHED */
  }
  
  /*
   * this kills every thread in the thread group. Note that any externally
   * wait4()-ing process will get the correct exit code - even if this
   * thread is not the thread group leader.
   */
  asmlinkage void sys_exit_group(int error_code)
  {
  	do_group_exit((error_code & 0xff) << 8);
  }

  static int eligible_child(pid_t pid, int options, struct task_struct *p)

  {
  	if (pid > 0) {
  		if (p->pid != pid)
  			return 0;
  	} else if (!pid) {
  		if (process_group(p) != process_group(current))
  			return 0;
  	} else if (pid != -1) {
  		if (process_group(p) != -pid)
  			return 0;
  	}
  
  	/*
  	 * Do not consider detached threads that are
  	 * not ptraced:
  	 */
  	if (p->exit_signal == -1 && !p->ptrace)
  		return 0;
  
  	/* Wait for all children (clone and not) if __WALL is set;
  	 * otherwise, wait for clone children *only* if __WCLONE is
  	 * set; otherwise, wait for non-clone children *only*.  (Note:
  	 * A "clone" child here is one that reports to its parent
  	 * using a signal other than SIGCHLD.) */
  	if (((p->exit_signal != SIGCHLD) ^ ((options & __WCLONE) != 0))
  	    && !(options & __WALL))
  		return 0;
  	/*
  	 * Do not consider thread group leaders that are
  	 * in a non-empty thread group:
  	 */

  	if (delay_group_leader(p))

  		return 2;
  
  	if (security_task_wait(p))
  		return 0;
  
  	return 1;
  }

  static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,

  			       int why, int status,
  			       struct siginfo __user *infop,
  			       struct rusage __user *rusagep)
  {
  	int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;

  	put_task_struct(p);
  	if (!retval)
  		retval = put_user(SIGCHLD, &infop->si_signo);
  	if (!retval)
  		retval = put_user(0, &infop->si_errno);
  	if (!retval)
  		retval = put_user((short)why, &infop->si_code);
  	if (!retval)
  		retval = put_user(pid, &infop->si_pid);
  	if (!retval)
  		retval = put_user(uid, &infop->si_uid);
  	if (!retval)
  		retval = put_user(status, &infop->si_status);
  	if (!retval)
  		retval = pid;
  	return retval;
  }
  
  /*
   * Handle sys_wait4 work for one task in state EXIT_ZOMBIE.  We hold
   * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
   * the lock and this task is uninteresting.  If we return nonzero, we have
   * released the lock and the system call should return.
   */

  static int wait_task_zombie(struct task_struct *p, int noreap,

  			    struct siginfo __user *infop,
  			    int __user *stat_addr, struct rusage __user *ru)
  {
  	unsigned long state;
  	int retval;
  	int status;
  
  	if (unlikely(noreap)) {
  		pid_t pid = p->pid;
  		uid_t uid = p->uid;
  		int exit_code = p->exit_code;
  		int why, status;
  
  		if (unlikely(p->exit_state != EXIT_ZOMBIE))
  			return 0;
  		if (unlikely(p->exit_signal == -1 && p->ptrace == 0))
  			return 0;
  		get_task_struct(p);
  		read_unlock(&tasklist_lock);
  		if ((exit_code & 0x7f) == 0) {
  			why = CLD_EXITED;
  			status = exit_code >> 8;
  		} else {
  			why = (exit_code & 0x80) ? CLD_DUMPED : CLD_KILLED;
  			status = exit_code & 0x7f;
  		}
  		return wait_noreap_copyout(p, pid, uid, why,
  					   status, infop, ru);
  	}
  
  	/*
  	 * Try to move the task's state to DEAD
  	 * only one thread is allowed to do this:
  	 */
  	state = xchg(&p->exit_state, EXIT_DEAD);
  	if (state != EXIT_ZOMBIE) {
  		BUG_ON(state != EXIT_DEAD);
  		return 0;
  	}
  	if (unlikely(p->exit_signal == -1 && p->ptrace == 0)) {
  		/*
  		 * This can only happen in a race with a ptraced thread
  		 * dying on another processor.
  		 */
  		return 0;
  	}
  
  	if (likely(p->real_parent == p->parent) && likely(p->signal)) {

  		struct signal_struct *psig;
  		struct signal_struct *sig;

  		/*
  		 * The resource counters for the group leader are in its
  		 * own task_struct.  Those for dead threads in the group
  		 * are in its signal_struct, as are those for the child
  		 * processes it has previously reaped.  All these
  		 * accumulate in the parent's signal_struct c* fields.
  		 *
  		 * We don't bother to take a lock here to protect these
  		 * p->signal fields, because they are only touched by
  		 * __exit_signal, which runs with tasklist_lock
  		 * write-locked anyway, and so is excluded here.  We do
  		 * need to protect the access to p->parent->signal fields,
  		 * as other threads in the parent group can be right
  		 * here reaping other children at the same time.
  		 */
  		spin_lock_irq(&p->parent->sighand->siglock);

  		psig = p->parent->signal;
  		sig = p->signal;
  		psig->cutime =
  			cputime_add(psig->cutime,

  			cputime_add(p->utime,

  			cputime_add(sig->utime,
  				    sig->cutime)));
  		psig->cstime =
  			cputime_add(psig->cstime,

  			cputime_add(p->stime,

  			cputime_add(sig->stime,
  				    sig->cstime)));
  		psig->cmin_flt +=
  			p->min_flt + sig->min_flt + sig->cmin_flt;
  		psig->cmaj_flt +=
  			p->maj_flt + sig->maj_flt + sig->cmaj_flt;
  		psig->cnvcsw +=
  			p->nvcsw + sig->nvcsw + sig->cnvcsw;
  		psig->cnivcsw +=
  			p->nivcsw + sig->nivcsw + sig->cnivcsw;

  		spin_unlock_irq(&p->parent->sighand->siglock);
  	}
  
  	/*
  	 * Now we are sure this task is interesting, and no other
  	 * thread can reap it because we set its state to EXIT_DEAD.
  	 */
  	read_unlock(&tasklist_lock);
  
  	retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
  	status = (p->signal->flags & SIGNAL_GROUP_EXIT)
  		? p->signal->group_exit_code : p->exit_code;
  	if (!retval && stat_addr)
  		retval = put_user(status, stat_addr);
  	if (!retval && infop)
  		retval = put_user(SIGCHLD, &infop->si_signo);
  	if (!retval && infop)
  		retval = put_user(0, &infop->si_errno);
  	if (!retval && infop) {
  		int why;
  
  		if ((status & 0x7f) == 0) {
  			why = CLD_EXITED;
  			status >>= 8;
  		} else {
  			why = (status & 0x80) ? CLD_DUMPED : CLD_KILLED;
  			status &= 0x7f;
  		}
  		retval = put_user((short)why, &infop->si_code);
  		if (!retval)
  			retval = put_user(status, &infop->si_status);
  	}
  	if (!retval && infop)
  		retval = put_user(p->pid, &infop->si_pid);
  	if (!retval && infop)
  		retval = put_user(p->uid, &infop->si_uid);
  	if (retval) {
  		// TODO: is this safe?
  		p->exit_state = EXIT_ZOMBIE;
  		return retval;
  	}
  	retval = p->pid;
  	if (p->real_parent != p->parent) {
  		write_lock_irq(&tasklist_lock);
  		/* Double-check with lock held.  */
  		if (p->real_parent != p->parent) {
  			__ptrace_unlink(p);
  			// TODO: is this safe?
  			p->exit_state = EXIT_ZOMBIE;
  			/*
  			 * If this is not a detached task, notify the parent.
  			 * If it's still not detached after that, don't release
  			 * it now.
  			 */
  			if (p->exit_signal != -1) {
  				do_notify_parent(p, p->exit_signal);
  				if (p->exit_signal != -1)
  					p = NULL;
  			}
  		}
  		write_unlock_irq(&tasklist_lock);
  	}
  	if (p != NULL)
  		release_task(p);
  	BUG_ON(!retval);
  	return retval;
  }
  
  /*
   * Handle sys_wait4 work for one task in state TASK_STOPPED.  We hold
   * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
   * the lock and this task is uninteresting.  If we return nonzero, we have
   * released the lock and the system call should return.
   */

  static int wait_task_stopped(struct task_struct *p, int delayed_group_leader,
  			     int noreap, struct siginfo __user *infop,

  			     int __user *stat_addr, struct rusage __user *ru)
  {
  	int retval, exit_code;
  
  	if (!p->exit_code)
  		return 0;
  	if (delayed_group_leader && !(p->ptrace & PT_PTRACED) &&
  	    p->signal && p->signal->group_stop_count > 0)
  		/*
  		 * A group stop is in progress and this is the group leader.
  		 * We won't report until all threads have stopped.
  		 */
  		return 0;
  
  	/*
  	 * Now we are pretty sure this task is interesting.
  	 * Make sure it doesn't get reaped out from under us while we
  	 * give up the lock and then examine it below.  We don't want to
  	 * keep holding onto the tasklist_lock while we call getrusage and
  	 * possibly take page faults for user memory.
  	 */
  	get_task_struct(p);
  	read_unlock(&tasklist_lock);
  
  	if (unlikely(noreap)) {
  		pid_t pid = p->pid;
  		uid_t uid = p->uid;
  		int why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
  
  		exit_code = p->exit_code;
  		if (unlikely(!exit_code) ||

  		    unlikely(p->state & TASK_TRACED))

  			goto bail_ref;
  		return wait_noreap_copyout(p, pid, uid,
  					   why, (exit_code << 8) | 0x7f,
  					   infop, ru);
  	}
  
  	write_lock_irq(&tasklist_lock);
  
  	/*
  	 * This uses xchg to be atomic with the thread resuming and setting
  	 * it.  It must also be done with the write lock held to prevent a
  	 * race with the EXIT_ZOMBIE case.
  	 */
  	exit_code = xchg(&p->exit_code, 0);
  	if (unlikely(p->exit_state)) {
  		/*
  		 * The task resumed and then died.  Let the next iteration
  		 * catch it in EXIT_ZOMBIE.  Note that exit_code might
  		 * already be zero here if it resumed and did _exit(0).
  		 * The task itself is dead and won't touch exit_code again;
  		 * other processors in this function are locked out.
  		 */
  		p->exit_code = exit_code;
  		exit_code = 0;
  	}
  	if (unlikely(exit_code == 0)) {
  		/*
  		 * Another thread in this function got to it first, or it
  		 * resumed, or it resumed and then died.
  		 */
  		write_unlock_irq(&tasklist_lock);
  bail_ref:
  		put_task_struct(p);
  		/*
  		 * We are returning to the wait loop without having successfully
  		 * removed the process and having released the lock. We cannot
  		 * continue, since the "p" task pointer is potentially stale.
  		 *
  		 * Return -EAGAIN, and do_wait() will restart the loop from the
  		 * beginning. Do _not_ re-acquire the lock.
  		 */
  		return -EAGAIN;
  	}
  
  	/* move to end of parent's list to avoid starvation */
  	remove_parent(p);

  	add_parent(p);

  
  	write_unlock_irq(&tasklist_lock);
  
  	retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
  	if (!retval && stat_addr)
  		retval = put_user((exit_code << 8) | 0x7f, stat_addr);
  	if (!retval && infop)
  		retval = put_user(SIGCHLD, &infop->si_signo);
  	if (!retval && infop)
  		retval = put_user(0, &infop->si_errno);
  	if (!retval && infop)
  		retval = put_user((short)((p->ptrace & PT_PTRACED)
  					  ? CLD_TRAPPED : CLD_STOPPED),
  				  &infop->si_code);
  	if (!retval && infop)
  		retval = put_user(exit_code, &infop->si_status);
  	if (!retval && infop)
  		retval = put_user(p->pid, &infop->si_pid);
  	if (!retval && infop)
  		retval = put_user(p->uid, &infop->si_uid);
  	if (!retval)
  		retval = p->pid;
  	put_task_struct(p);
  
  	BUG_ON(!retval);
  	return retval;
  }
  
  /*
   * Handle do_wait work for one task in a live, non-stopped state.
   * read_lock(&tasklist_lock) on entry.  If we return zero, we still hold
   * the lock and this task is uninteresting.  If we return nonzero, we have
   * released the lock and the system call should return.
   */

  static int wait_task_continued(struct task_struct *p, int noreap,

  			       struct siginfo __user *infop,
  			       int __user *stat_addr, struct rusage __user *ru)
  {
  	int retval;
  	pid_t pid;
  	uid_t uid;
  
  	if (unlikely(!p->signal))
  		return 0;
  
  	if (!(p->signal->flags & SIGNAL_STOP_CONTINUED))
  		return 0;
  
  	spin_lock_irq(&p->sighand->siglock);
  	/* Re-check with the lock held.  */
  	if (!(p->signal->flags & SIGNAL_STOP_CONTINUED)) {
  		spin_unlock_irq(&p->sighand->siglock);
  		return 0;
  	}
  	if (!noreap)
  		p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
  	spin_unlock_irq(&p->sighand->siglock);
  
  	pid = p->pid;
  	uid = p->uid;
  	get_task_struct(p);
  	read_unlock(&tasklist_lock);
  
  	if (!infop) {
  		retval = ru ? getrusage(p, RUSAGE_BOTH, ru) : 0;
  		put_task_struct(p);
  		if (!retval && stat_addr)
  			retval = put_user(0xffff, stat_addr);
  		if (!retval)
  			retval = p->pid;
  	} else {
  		retval = wait_noreap_copyout(p, pid, uid,
  					     CLD_CONTINUED, SIGCONT,
  					     infop, ru);
  		BUG_ON(retval == 0);
  	}
  
  	return retval;
  }
  
  
  static inline int my_ptrace_child(struct task_struct *p)
  {
  	if (!(p->ptrace & PT_PTRACED))
  		return 0;
  	if (!(p->ptrace & PT_ATTACHED))
  		return 1;
  	/*
  	 * This child was PTRACE_ATTACH'd.  We should be seeing it only if
  	 * we are the attacher.  If we are the real parent, this is a race
  	 * inside ptrace_attach.  It is waiting for the tasklist_lock,
  	 * which we have to switch the parent links, but has already set
  	 * the flags in p->ptrace.
  	 */
  	return (p->parent != p->real_parent);
  }
  
  static long do_wait(pid_t pid, int options, struct siginfo __user *infop,
  		    int __user *stat_addr, struct rusage __user *ru)
  {
  	DECLARE_WAITQUEUE(wait, current);
  	struct task_struct *tsk;
  	int flag, retval;
  
  	add_wait_queue(&current->signal->wait_chldexit,&wait);
  repeat:
  	/*
  	 * We will set this flag if we see any child that might later
  	 * match our criteria, even if we are not able to reap it yet.
  	 */
  	flag = 0;
  	current->state = TASK_INTERRUPTIBLE;
  	read_lock(&tasklist_lock);
  	tsk = current;
  	do {
  		struct task_struct *p;
  		struct list_head *_p;
  		int ret;
  
  		list_for_each(_p,&tsk->children) {

  			p = list_entry(_p, struct task_struct, sibling);

  
  			ret = eligible_child(pid, options, p);
  			if (!ret)
  				continue;
  
  			switch (p->state) {
  			case TASK_TRACED:

  				/*
  				 * When we hit the race with PTRACE_ATTACH,
  				 * we will not report this child.  But the
  				 * race means it has not yet been moved to
  				 * our ptrace_children list, so we need to
  				 * set the flag here to avoid a spurious ECHILD
  				 * when the race happens with the only child.
  				 */
  				flag = 1;

  				if (!my_ptrace_child(p))
  					continue;
  				/*FALLTHROUGH*/
  			case TASK_STOPPED:
  				/*
  				 * It's stopped now, so it might later
  				 * continue, exit, or stop again.
  				 */
  				flag = 1;
  				if (!(options & WUNTRACED) &&
  				    !my_ptrace_child(p))
  					continue;
  				retval = wait_task_stopped(p, ret == 2,
  							   (options & WNOWAIT),
  							   infop,
  							   stat_addr, ru);
  				if (retval == -EAGAIN)
  					goto repeat;
  				if (retval != 0) /* He released the lock.  */
  					goto end;
  				break;
  			default:
  			// case EXIT_DEAD:
  				if (p->exit_state == EXIT_DEAD)
  					continue;
  			// case EXIT_ZOMBIE:
  				if (p->exit_state == EXIT_ZOMBIE) {
  					/*
  					 * Eligible but we cannot release
  					 * it yet:
  					 */
  					if (ret == 2)
  						goto check_continued;
  					if (!likely(options & WEXITED))
  						continue;
  					retval = wait_task_zombie(
  						p, (options & WNOWAIT),
  						infop, stat_addr, ru);
  					/* He released the lock.  */
  					if (retval != 0)
  						goto end;
  					break;
  				}
  check_continued:
  				/*
  				 * It's running now, so it might later
  				 * exit, stop, or stop and then continue.
  				 */
  				flag = 1;
  				if (!unlikely(options & WCONTINUED))
  					continue;
  				retval = wait_task_continued(
  					p, (options & WNOWAIT),
  					infop, stat_addr, ru);
  				if (retval != 0) /* He released the lock.  */
  					goto end;
  				break;
  			}
  		}
  		if (!flag) {
  			list_for_each(_p, &tsk->ptrace_children) {
  				p = list_entry(_p, struct task_struct,
  						ptrace_list);
  				if (!eligible_child(pid, options, p))
  					continue;
  				flag = 1;
  				break;
  			}
  		}
  		if (options & __WNOTHREAD)
  			break;
  		tsk = next_thread(tsk);

  		BUG_ON(tsk->signal != current->signal);

  	} while (tsk != current);
  
  	read_unlock(&tasklist_lock);
  	if (flag) {
  		retval = 0;
  		if (options & WNOHANG)
  			goto end;
  		retval = -ERESTARTSYS;
  		if (signal_pending(current))
  			goto end;
  		schedule();
  		goto repeat;
  	}
  	retval = -ECHILD;
  end:
  	current->state = TASK_RUNNING;
  	remove_wait_queue(&current->signal->wait_chldexit,&wait);
  	if (infop) {
  		if (retval > 0)
  		retval = 0;
  		else {
  			/*
  			 * For a WNOHANG return, clear out all the fields
  			 * we would set so the user can easily tell the
  			 * difference.
  			 */
  			if (!retval)
  				retval = put_user(0, &infop->si_signo);
  			if (!retval)
  				retval = put_user(0, &infop->si_errno);
  			if (!retval)
  				retval = put_user(0, &infop->si_code);
  			if (!retval)
  				retval = put_user(0, &infop->si_pid);
  			if (!retval)
  				retval = put_user(0, &infop->si_uid);
  			if (!retval)
  				retval = put_user(0, &infop->si_status);
  		}
  	}
  	return retval;
  }
  
  asmlinkage long sys_waitid(int which, pid_t pid,
  			   struct siginfo __user *infop, int options,
  			   struct rusage __user *ru)
  {
  	long ret;
  
  	if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
  		return -EINVAL;
  	if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
  		return -EINVAL;
  
  	switch (which) {
  	case P_ALL:
  		pid = -1;
  		break;
  	case P_PID:
  		if (pid <= 0)
  			return -EINVAL;
  		break;
  	case P_PGID:
  		if (pid <= 0)
  			return -EINVAL;
  		pid = -pid;
  		break;
  	default:
  		return -EINVAL;
  	}
  
  	ret = do_wait(pid, options, infop, NULL, ru);
  
  	/* avoid REGPARM breakage on x86: */
  	prevent_tail_call(ret);
  	return ret;
  }
  
  asmlinkage long sys_wait4(pid_t pid, int __user *stat_addr,
  			  int options, struct rusage __user *ru)
  {
  	long ret;
  
  	if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
  			__WNOTHREAD|__WCLONE|__WALL))
  		return -EINVAL;
  	ret = do_wait(pid, options | WEXITED, NULL, stat_addr, ru);
  
  	/* avoid REGPARM breakage on x86: */
  	prevent_tail_call(ret);
  	return ret;
  }
  
  #ifdef __ARCH_WANT_SYS_WAITPID
  
  /*
   * sys_waitpid() remains for compatibility. waitpid() should be
   * implemented by calling sys_wait4() from libc.a.
   */
  asmlinkage long sys_waitpid(pid_t pid, int __user *stat_addr, int options)
  {
  	return sys_wait4(pid, stat_addr, options, NULL);
  }
  
  #endif