exit.c 41.3 KB
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/*
 *  linux/kernel/exit.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/module.h>
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#include <linux/capability.h>
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#include <linux/completion.h>
#include <linux/personality.h>
#include <linux/tty.h>
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#include <linux/mnt_namespace.h>
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#include <linux/key.h>
#include <linux/security.h>
#include <linux/cpu.h>
#include <linux/acct.h>
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#include <linux/tsacct_kern.h>
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#include <linux/file.h>
#include <linux/binfmts.h>
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#include <linux/nsproxy.h>
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#include <linux/pid_namespace.h>
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#include <linux/ptrace.h>
#include <linux/profile.h>
#include <linux/mount.h>
#include <linux/proc_fs.h>
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#include <linux/kthread.h>
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#include <linux/mempolicy.h>
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#include <linux/taskstats_kern.h>
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#include <linux/delayacct.h>
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#include <linux/freezer.h>
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#include <linux/cgroup.h>
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#include <linux/syscalls.h>
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#include <linux/signal.h>
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#include <linux/posix-timers.h>
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#include <linux/cn_proc.h>
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#include <linux/mutex.h>
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#include <linux/futex.h>
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#include <linux/compat.h>
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#include <linux/pipe_fs_i.h>
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#include <linux/audit.h> /* for audit_free() */
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#include <linux/resource.h>
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#include <linux/blkdev.h>
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#include <linux/task_io_accounting_ops.h>
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#include <asm/uaccess.h>
#include <asm/unistd.h>
#include <asm/pgtable.h>
#include <asm/mmu_context.h>

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static void exit_mm(struct task_struct * tsk);

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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);
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		list_del_rcu(&p->tasks);
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		__get_cpu_var(process_counts)--;
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	}
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	list_del_rcu(&p->thread_group);
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	remove_parent(p);
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}

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/*
 * 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:
		 */
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		if (sig->group_exit_task && atomic_read(&sig->count) == sig->notify_count)
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			wake_up_process(sig->group_exit_task);
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		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);
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		sig->gtime = cputime_add(sig->gtime, tsk->gtime);
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		sig->min_flt += tsk->min_flt;
		sig->maj_flt += tsk->maj_flt;
		sig->nvcsw += tsk->nvcsw;
		sig->nivcsw += tsk->nivcsw;
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		sig->inblock += task_io_get_inblock(tsk);
		sig->oublock += task_io_get_oublock(tsk);
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		sig->sum_sched_runtime += tsk->se.sum_exec_runtime;
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		sig = NULL; /* Marker for below. */
	}

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	__unhash_process(tsk);

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	tsk->signal = NULL;
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	tsk->sighand = NULL;
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	spin_unlock(&sighand->siglock);
	rcu_read_unlock();

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

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

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void release_task(struct task_struct * p)
{
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	struct task_struct *leader;
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	int zap_leader;
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repeat:
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	atomic_dec(&p->user->processes);
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	proc_flush_task(p);
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	write_lock_irq(&tasklist_lock);
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	ptrace_unlink(p);
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	BUG_ON(!list_empty(&p->ptrace_list) || !list_empty(&p->ptrace_children));
	__exit_signal(p);
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	/*
	 * 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);
	}

	write_unlock_irq(&tasklist_lock);
	release_thread(p);
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	call_rcu(&p->rcu, delayed_put_task_struct);
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	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...
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 *
 * The caller must hold rcu lock or the tasklist lock.
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 */
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struct pid *session_of_pgrp(struct pid *pgrp)
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{
	struct task_struct *p;
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	struct pid *sid = NULL;
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	p = pid_task(pgrp, PIDTYPE_PGID);
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	if (p == NULL)
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		p = pid_task(pgrp, PIDTYPE_PID);
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	if (p != NULL)
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		sid = task_session(p);
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	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?"
 */
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static int will_become_orphaned_pgrp(struct pid *pgrp, struct task_struct *ignored_task)
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{
	struct task_struct *p;

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	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
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		if ((p == ignored_task) ||
		    (p->exit_state && thread_group_empty(p)) ||
		    is_global_init(p->real_parent))
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			continue;
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		if (task_pgrp(p->real_parent) != pgrp &&
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		    task_session(p->real_parent) == task_session(p))
			return 0;
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	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
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	return 1;
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}

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int is_current_pgrp_orphaned(void)
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{
	int retval;

	read_lock(&tasklist_lock);
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	retval = will_become_orphaned_pgrp(task_pgrp(current), NULL);
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	read_unlock(&tasklist_lock);

	return retval;
}

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static int has_stopped_jobs(struct pid *pgrp)
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{
	int retval = 0;
	struct task_struct *p;

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	do_each_pid_task(pgrp, PIDTYPE_PGID, p) {
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		if (!task_is_stopped(p))
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			continue;
		retval = 1;
		break;
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	} while_each_pid_task(pgrp, PIDTYPE_PGID, p);
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	return retval;
}

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/*
 * 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)
 */
static void
kill_orphaned_pgrp(struct task_struct *tsk, struct task_struct *parent)
{
	struct pid *pgrp = task_pgrp(tsk);
	struct task_struct *ignored_task = tsk;

	if (!parent)
		 /* exit: our father is in a different pgrp than
		  * we are and we were the only connection outside.
		  */
		parent = tsk->real_parent;
	else
		/* reparent: our child is in a different pgrp than
		 * we are, and it was the only connection outside.
		 */
		ignored_task = NULL;

	if (task_pgrp(parent) != pgrp &&
	    task_session(parent) == task_session(tsk) &&
	    will_become_orphaned_pgrp(pgrp, ignored_task) &&
	    has_stopped_jobs(pgrp)) {
		__kill_pgrp_info(SIGHUP, SEND_SIG_PRIV, pgrp);
		__kill_pgrp_info(SIGCONT, SEND_SIG_PRIV, pgrp);
	}
}

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/**
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 * reparent_to_kthreadd - Reparent the calling kernel thread to kthreadd
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 *
 * If a kernel thread is launched as a result of a system call, or if
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 * it ever exits, it should generally reparent itself to kthreadd so it
 * isn't in the way of other processes and is correctly cleaned up on exit.
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 *
 * 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.
 *
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 * NOTE that reparent_to_kthreadd() gives the caller full capabilities.
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 */
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static void reparent_to_kthreadd(void)
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{
	write_lock_irq(&tasklist_lock);

	ptrace_unlink(current);
	/* Reparent to init */
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	remove_parent(current);
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	current->real_parent = current->parent = kthreadd_task;
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	add_parent(current);
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	/* Set the exit signal to SIGCHLD so we signal init on exit */
	current->exit_signal = SIGCHLD;

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	if (task_nice(current) < 0)
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		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);
}

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void __set_special_pids(struct pid *pid)
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{
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	struct task_struct *curr = current->group_leader;
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	pid_t nr = pid_nr(pid);
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	if (task_session(curr) != pid) {
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		detach_pid(curr, PIDTYPE_SID);
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		attach_pid(curr, PIDTYPE_SID, pid);
		set_task_session(curr, nr);
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	}
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	if (task_pgrp(curr) != pid) {
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		detach_pid(curr, PIDTYPE_PGID);
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		attach_pid(curr, PIDTYPE_PGID, pid);
		set_task_pgrp(curr, nr);
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	}
}

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static void set_special_pids(struct pid *pid)
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{
	write_lock_irq(&tasklist_lock);
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	__set_special_pids(pid);
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	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)
{
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	if (!valid_signal(sig) || sig < 1)
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		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)
{
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	if (!valid_signal(sig) || sig < 1)
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		return -EINVAL;

	spin_lock_irq(&current->sighand->siglock);
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	current->sighand->action[(sig)-1].sa.sa_handler = SIG_IGN;
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	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);
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	/*
	 * We don't want to have TIF_FREEZE set if the system-wide hibernation
	 * or suspend transition begins right now.
	 */
	current->flags |= PF_NOFREEZE;
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	if (current->nsproxy != &init_nsproxy) {
		get_nsproxy(&init_nsproxy);
		switch_task_namespaces(current, &init_nsproxy);
	}
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	set_special_pids(&init_struct_pid);
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	proc_clear_tty(current);
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	/* 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);
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	exit_files(current);
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	current->files = init_task.files;
	atomic_inc(&current->files->count);

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	reparent_to_kthreadd();
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}

EXPORT_SYMBOL(daemonize);

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static void close_files(struct files_struct * files)
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{
	int i, j;
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	struct fdtable *fdt;
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	j = 0;
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	/*
	 * It is safe to dereference the fd table without RCU or
	 * ->file_lock because this is the last reference to the
	 * files structure.
	 */
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	fdt = files_fdtable(files);
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	for (;;) {
		unsigned long set;
		i = j * __NFDBITS;
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		if (i >= fdt->max_fds)
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			break;
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		set = fdt->open_fds->fds_bits[j++];
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		while (set) {
			if (set & 1) {
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				struct file * file = xchg(&fdt->fd[i], NULL);
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				if (file) {
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					filp_close(file, files);
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					cond_resched();
				}
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			}
			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;
}

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void put_files_struct(struct files_struct *files)
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{
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	struct fdtable *fdt;

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	if (atomic_dec_and_test(&files->count)) {
		close_files(files);
		/*
		 * Free the fd and fdset arrays if we expanded them.
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		 * If the fdtable was embedded, pass files for freeing
		 * at the end of the RCU grace period. Otherwise,
		 * you can free files immediately.
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		 */
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		fdt = files_fdtable(files);
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		if (fdt != &files->fdtab)
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			kmem_cache_free(files_cachep, files);
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		free_fdtable(fdt);
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	}
}

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void reset_files_struct(struct files_struct *files)
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{
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	struct task_struct *tsk = current;
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	struct files_struct *old;

	old = tsk->files;
	task_lock(tsk);
	tsk->files = files;
	task_unlock(tsk);
	put_files_struct(old);
}

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void exit_files(struct task_struct *tsk)
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{
	struct files_struct * files = tsk->files;

	if (files) {
		task_lock(tsk);
		tsk->files = NULL;
		task_unlock(tsk);
		put_files_struct(files);
	}
}

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void put_fs_struct(struct fs_struct *fs)
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{
	/* No need to hold fs->lock if we are killing it */
	if (atomic_dec_and_test(&fs->count)) {
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		path_put(&fs->root);
		path_put(&fs->pwd);
		if (fs->altroot.dentry)
			path_put(&fs->altroot);
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		kmem_cache_free(fs_cachep, fs);
	}
}

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void exit_fs(struct task_struct *tsk)
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{
	struct fs_struct * fs = tsk->fs;

	if (fs) {
		task_lock(tsk);
		tsk->fs = NULL;
		task_unlock(tsk);
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		put_fs_struct(fs);
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	}
}

EXPORT_SYMBOL_GPL(exit_fs);

/*
 * Turn us into a lazy TLB process if we
 * aren't already..
 */
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static void exit_mm(struct task_struct * tsk)
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{
	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);
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	BUG_ON(mm != tsk->active_mm);
L
Linus Torvalds 已提交
591 592 593 594 595
	/* more a memory barrier than a real lock */
	task_lock(tsk);
	tsk->mm = NULL;
	up_read(&mm->mmap_sem);
	enter_lazy_tlb(mm, current);
596 597
	/* We don't want this task to be frozen prematurely */
	clear_freeze_flag(tsk);
L
Linus Torvalds 已提交
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	task_unlock(tsk);
	mmput(mm);
}

602 603
static void
reparent_thread(struct task_struct *p, struct task_struct *father, int traced)
L
Linus Torvalds 已提交
604
{
605 606 607 608
	if (p->pdeath_signal)
		/* We already hold the tasklist_lock here.  */
		group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);

L
Linus Torvalds 已提交
609 610 611 612 613 614 615 616 617 618 619
	/* 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;
620
		remove_parent(p);
L
Linus Torvalds 已提交
621
		p->parent = p->real_parent;
622
		add_parent(p);
L
Linus Torvalds 已提交
623

M
Matthew Wilcox 已提交
624
		if (task_is_traced(p)) {
L
Linus Torvalds 已提交
625 626 627 628 629 630 631 632 633
			/*
			 * If it was at a trace stop, turn it into
			 * a normal stop since it's no longer being
			 * traced.
			 */
			ptrace_untrace(p);
		}
	}

634 635 636 637 638 639 640 641 642 643 644 645 646 647 648 649 650
	/* If this is a threaded reparent there is no need to
	 * notify anyone anything has happened.
	 */
	if (p->real_parent->group_leader == father->group_leader)
		return;

	/* We don't want people slaying init.  */
	if (p->exit_signal != -1)
		p->exit_signal = SIGCHLD;

	/* If we'd notified the old parent about this child's death,
	 * also notify the new parent.
	 */
	if (!traced && p->exit_state == EXIT_ZOMBIE &&
	    p->exit_signal != -1 && thread_group_empty(p))
		do_notify_parent(p, p->exit_signal);

651
	kill_orphaned_pgrp(p, father);
L
Linus Torvalds 已提交
652 653 654 655 656 657
}

/*
 * 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
658 659
 * the child reaper process (ie "init") in our pid
 * space.
L
Linus Torvalds 已提交
660
 */
661
static void forget_original_parent(struct task_struct *father)
L
Linus Torvalds 已提交
662
{
663
	struct task_struct *p, *n, *reaper = father;
664 665 666 667 668
	struct list_head ptrace_dead;

	INIT_LIST_HEAD(&ptrace_dead);

	write_lock_irq(&tasklist_lock);
L
Linus Torvalds 已提交
669 670 671 672

	do {
		reaper = next_thread(reaper);
		if (reaper == father) {
673
			reaper = task_child_reaper(father);
L
Linus Torvalds 已提交
674 675
			break;
		}
676
	} while (reaper->flags & PF_EXITING);
L
Linus Torvalds 已提交
677 678 679 680 681 682 683 684 685

	/*
	 * There are only two places where our children can be:
	 *
	 * - in our child list
	 * - in our ptraced child list
	 *
	 * Search them and reparent children.
	 */
686
	list_for_each_entry_safe(p, n, &father->children, sibling) {
L
Linus Torvalds 已提交
687 688 689 690 691 692 693 694 695
		int ptrace;

		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 */
696
			p->real_parent = reaper;
L
Linus Torvalds 已提交
697 698 699 700 701 702 703 704 705 706 707 708 709 710 711 712
			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))
713
			list_add(&p->ptrace_list, &ptrace_dead);
L
Linus Torvalds 已提交
714
	}
715

716
	list_for_each_entry_safe(p, n, &father->ptrace_children, ptrace_list) {
717
		p->real_parent = reaper;
L
Linus Torvalds 已提交
718 719
		reparent_thread(p, father, 1);
	}
720 721 722 723 724 725 726 727 728 729

	write_unlock_irq(&tasklist_lock);
	BUG_ON(!list_empty(&father->children));
	BUG_ON(!list_empty(&father->ptrace_children));

	list_for_each_entry_safe(p, n, &ptrace_dead, ptrace_list) {
		list_del_init(&p->ptrace_list);
		release_task(p);
	}

L
Linus Torvalds 已提交
730 731 732 733 734 735
}

/*
 * Send signals to all our closest relatives so that they know
 * to properly mourn us..
 */
736
static void exit_notify(struct task_struct *tsk, int group_dead)
L
Linus Torvalds 已提交
737 738 739 740 741 742 743 744 745 746 747
{
	int state;

	/*
	 * 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)
	 */
748
	forget_original_parent(tsk);
749
	exit_task_namespaces(tsk);
L
Linus Torvalds 已提交
750

751
	write_lock_irq(&tasklist_lock);
752 753
	if (group_dead)
		kill_orphaned_pgrp(tsk->group_leader, NULL);
L
Linus Torvalds 已提交
754

755
	/* Let father know we died
L
Linus Torvalds 已提交
756 757
	 *
	 * Thread signals are configurable, but you aren't going to use
758
	 * that to send signals to arbitary processes.
L
Linus Torvalds 已提交
759 760 761 762 763 764 765 766 767 768 769
	 * 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 &&
770 771
	    (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
	     tsk->self_exec_id != tsk->parent_exec_id)
L
Linus Torvalds 已提交
772 773 774 775 776 777 778 779 780 781 782 783 784 785 786 787
	    && !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;
788
	if (tsk->exit_signal == -1 && likely(!tsk->ptrace))
L
Linus Torvalds 已提交
789 790 791
		state = EXIT_DEAD;
	tsk->exit_state = state;

792 793 794 795 796
	if (thread_group_leader(tsk) &&
	    tsk->signal->notify_count < 0 &&
	    tsk->signal->group_exit_task)
		wake_up_process(tsk->signal->group_exit_task);

L
Linus Torvalds 已提交
797 798 799 800 801 802 803
	write_unlock_irq(&tasklist_lock);

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

804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821 822 823 824 825 826 827 828 829 830 831
#ifdef CONFIG_DEBUG_STACK_USAGE
static void check_stack_usage(void)
{
	static DEFINE_SPINLOCK(low_water_lock);
	static int lowest_to_date = THREAD_SIZE;
	unsigned long *n = end_of_stack(current);
	unsigned long free;

	while (*n == 0)
		n++;
	free = (unsigned long)n - (unsigned long)end_of_stack(current);

	if (free >= lowest_to_date)
		return;

	spin_lock(&low_water_lock);
	if (free < lowest_to_date) {
		printk(KERN_WARNING "%s used greatest stack depth: %lu bytes "
				"left\n",
				current->comm, free);
		lowest_to_date = free;
	}
	spin_unlock(&low_water_lock);
}
#else
static inline void check_stack_usage(void) {}
#endif

832 833
static inline void exit_child_reaper(struct task_struct *tsk)
{
834
	if (likely(tsk->group_leader != task_child_reaper(tsk)))
835 836
		return;

837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855 856 857 858 859 860 861 862
	if (tsk->nsproxy->pid_ns == &init_pid_ns)
		panic("Attempted to kill init!");

	/*
	 * @tsk is the last thread in the 'cgroup-init' and is exiting.
	 * Terminate all remaining processes in the namespace and reap them
	 * before exiting @tsk.
	 *
	 * Note that @tsk (last thread of cgroup-init) may not necessarily
	 * be the child-reaper (i.e main thread of cgroup-init) of the
	 * namespace i.e the child_reaper may have already exited.
	 *
	 * Even after a child_reaper exits, we let it inherit orphaned children,
	 * because, pid_ns->child_reaper remains valid as long as there is
	 * at least one living sub-thread in the cgroup init.

	 * This living sub-thread of the cgroup-init will be notified when
	 * a child inherited by the 'child-reaper' exits (do_notify_parent()
	 * uses __group_send_sig_info()). Further, when reaping child processes,
	 * do_wait() iterates over children of all living sub threads.

	 * i.e even though 'child_reaper' thread is listed as the parent of the
	 * orphaned children, any living sub-thread in the cgroup-init can
	 * perform the role of the child_reaper.
	 */
	zap_pid_ns_processes(tsk->nsproxy->pid_ns);
863 864
}

865
NORET_TYPE void do_exit(long code)
L
Linus Torvalds 已提交
866 867 868 869 870 871
{
	struct task_struct *tsk = current;
	int group_dead;

	profile_task_exit(tsk);

872 873
	WARN_ON(atomic_read(&tsk->fs_excl));

L
Linus Torvalds 已提交
874 875 876 877 878 879 880 881 882 883
	if (unlikely(in_interrupt()))
		panic("Aiee, killing interrupt handler!");
	if (unlikely(!tsk->pid))
		panic("Attempted to kill the idle task!");

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

884 885 886 887 888 889 890
	/*
	 * 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!\n");
891 892 893 894 895 896 897 898 899 900
		/*
		 * We can do this unlocked here. The futex code uses
		 * this flag just to verify whether the pi state
		 * cleanup has been done or not. In the worst case it
		 * loops once more. We pretend that the cleanup was
		 * done as there is no way to return. Either the
		 * OWNER_DIED bit is set by now or we push the blocked
		 * task into the wait for ever nirwana as well.
		 */
		tsk->flags |= PF_EXITPIDONE;
901 902
		if (tsk->io_context)
			exit_io_context();
903 904 905 906
		set_current_state(TASK_UNINTERRUPTIBLE);
		schedule();
	}

O
Oleg Nesterov 已提交
907
	exit_signals(tsk);  /* sets PF_EXITING */
908 909 910 911
	/*
	 * tsk->flags are checked in the futex code to protect against
	 * an exiting task cleaning up the robust pi futexes.
	 */
912 913
	smp_mb();
	spin_unlock_wait(&tsk->pi_lock);
L
Linus Torvalds 已提交
914 915 916

	if (unlikely(in_atomic()))
		printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
917
				current->comm, task_pid_nr(current),
L
Linus Torvalds 已提交
918 919 920
				preempt_count());

	acct_update_integrals(tsk);
921 922 923 924
	if (tsk->mm) {
		update_hiwater_rss(tsk->mm);
		update_hiwater_vm(tsk->mm);
	}
L
Linus Torvalds 已提交
925
	group_dead = atomic_dec_and_test(&tsk->signal->live);
926
	if (group_dead) {
927
		exit_child_reaper(tsk);
928
		hrtimer_cancel(&tsk->signal->real_timer);
929
		exit_itimers(tsk->signal);
930
	}
931
	acct_collect(code, group_dead);
932
#ifdef CONFIG_FUTEX
933 934
	if (unlikely(tsk->robust_list))
		exit_robust_list(tsk);
935
#ifdef CONFIG_COMPAT
936 937
	if (unlikely(tsk->compat_robust_list))
		compat_exit_robust_list(tsk);
938
#endif
939
#endif
M
Miloslav Trmac 已提交
940 941
	if (group_dead)
		tty_audit_exit();
942 943
	if (unlikely(tsk->audit_context))
		audit_free(tsk);
944

945
	tsk->exit_code = code;
946
	taskstats_exit(tsk, group_dead);
947

L
Linus Torvalds 已提交
948 949
	exit_mm(tsk);

950
	if (group_dead)
951
		acct_process();
L
Linus Torvalds 已提交
952
	exit_sem(tsk);
953 954
	exit_files(tsk);
	exit_fs(tsk);
955
	check_stack_usage();
L
Linus Torvalds 已提交
956
	exit_thread();
957
	cgroup_exit(tsk, 1);
L
Linus Torvalds 已提交
958 959 960 961 962
	exit_keys(tsk);

	if (group_dead && tsk->signal->leader)
		disassociate_ctty(1);

A
Al Viro 已提交
963
	module_put(task_thread_info(tsk)->exec_domain->module);
L
Linus Torvalds 已提交
964 965 966
	if (tsk->binfmt)
		module_put(tsk->binfmt->module);

M
Matt Helsley 已提交
967
	proc_exit_connector(tsk);
968
	exit_notify(tsk, group_dead);
L
Linus Torvalds 已提交
969 970 971 972
#ifdef CONFIG_NUMA
	mpol_free(tsk->mempolicy);
	tsk->mempolicy = NULL;
#endif
973
#ifdef CONFIG_FUTEX
974 975 976 977 978 979 980 981
	/*
	 * 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);
982
#endif
983
	/*
984
	 * Make sure we are holding no locks:
985
	 */
986
	debug_check_no_locks_held(tsk);
987 988 989 990 991 992
	/*
	 * We can do this unlocked here. The futex code uses this flag
	 * just to verify whether the pi state cleanup has been done
	 * or not. In the worst case it loops once more.
	 */
	tsk->flags |= PF_EXITPIDONE;
L
Linus Torvalds 已提交
993

994 995 996
	if (tsk->io_context)
		exit_io_context();

997 998 999
	if (tsk->splice_pipe)
		__free_pipe_info(tsk->splice_pipe);

C
Coywolf Qi Hunt 已提交
1000
	preempt_disable();
O
Oleg Nesterov 已提交
1001
	/* causes final put_task_struct in finish_task_switch(). */
1002
	tsk->state = TASK_DEAD;
C
Coywolf Qi Hunt 已提交
1003

L
Linus Torvalds 已提交
1004 1005 1006
	schedule();
	BUG();
	/* Avoid "noreturn function does return".  */
A
Alan Cox 已提交
1007 1008
	for (;;)
		cpu_relax();	/* For when BUG is null */
L
Linus Torvalds 已提交
1009 1010
}

1011 1012
EXPORT_SYMBOL_GPL(do_exit);

L
Linus Torvalds 已提交
1013 1014 1015 1016
NORET_TYPE void complete_and_exit(struct completion *comp, long code)
{
	if (comp)
		complete(comp);
O
Oleg Nesterov 已提交
1017

L
Linus Torvalds 已提交
1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042
	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);
1043
		if (signal_group_exit(sig))
L
Linus Torvalds 已提交
1044 1045 1046 1047
			/* Another thread got here before we took the lock.  */
			exit_code = sig->group_exit_code;
		else {
			sig->group_exit_code = exit_code;
1048
			sig->flags = SIGNAL_GROUP_EXIT;
L
Linus Torvalds 已提交
1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067
			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);
}

E
Eric W. Biederman 已提交
1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079
static struct pid *task_pid_type(struct task_struct *task, enum pid_type type)
{
	struct pid *pid = NULL;
	if (type == PIDTYPE_PID)
		pid = task->pids[type].pid;
	else if (type < PIDTYPE_MAX)
		pid = task->group_leader->pids[type].pid;
	return pid;
}

static int eligible_child(enum pid_type type, struct pid *pid, int options,
			  struct task_struct *p)
L
Linus Torvalds 已提交
1080
{
1081 1082
	int err;

E
Eric W. Biederman 已提交
1083 1084
	if (type < PIDTYPE_MAX) {
		if (task_pid_type(p, type) != pid)
L
Linus Torvalds 已提交
1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100 1101 1102 1103
			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;

1104
	err = security_task_wait(p);
O
Oleg Nesterov 已提交
1105 1106
	if (likely(!err))
		return 1;
L
Linus Torvalds 已提交
1107

E
Eric W. Biederman 已提交
1108
	if (type != PIDTYPE_PID)
O
Oleg Nesterov 已提交
1109 1110 1111 1112
		return 0;
	/* This child was explicitly requested, abort */
	read_unlock(&tasklist_lock);
	return err;
L
Linus Torvalds 已提交
1113 1114
}

1115
static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
L
Linus Torvalds 已提交
1116 1117 1118 1119 1120
			       int why, int status,
			       struct siginfo __user *infop,
			       struct rusage __user *rusagep)
{
	int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1121

L
Linus Torvalds 已提交
1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145
	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.
 */
1146
static int wait_task_zombie(struct task_struct *p, int noreap,
L
Linus Torvalds 已提交
1147 1148 1149 1150
			    struct siginfo __user *infop,
			    int __user *stat_addr, struct rusage __user *ru)
{
	unsigned long state;
1151
	int retval, status, traced;
1152
	pid_t pid = task_pid_vnr(p);
L
Linus Torvalds 已提交
1153 1154 1155 1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181

	if (unlikely(noreap)) {
		uid_t uid = p->uid;
		int exit_code = p->exit_code;
		int why, status;

		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;
	}

1182 1183 1184 1185
	/* traced means p->ptrace, but not vice versa */
	traced = (p->real_parent != p->parent);

	if (likely(!traced)) {
1186 1187 1188
		struct signal_struct *psig;
		struct signal_struct *sig;

L
Linus Torvalds 已提交
1189 1190 1191 1192 1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204
		/*
		 * 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);
1205 1206 1207 1208
		psig = p->parent->signal;
		sig = p->signal;
		psig->cutime =
			cputime_add(psig->cutime,
L
Linus Torvalds 已提交
1209
			cputime_add(p->utime,
1210 1211 1212 1213
			cputime_add(sig->utime,
				    sig->cutime)));
		psig->cstime =
			cputime_add(psig->cstime,
L
Linus Torvalds 已提交
1214
			cputime_add(p->stime,
1215 1216
			cputime_add(sig->stime,
				    sig->cstime)));
1217 1218 1219 1220 1221
		psig->cgtime =
			cputime_add(psig->cgtime,
			cputime_add(p->gtime,
			cputime_add(sig->gtime,
				    sig->cgtime)));
1222 1223 1224 1225 1226 1227 1228 1229
		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;
1230 1231 1232 1233 1234 1235
		psig->cinblock +=
			task_io_get_inblock(p) +
			sig->inblock + sig->cinblock;
		psig->coublock +=
			task_io_get_oublock(p) +
			sig->oublock + sig->coublock;
L
Linus Torvalds 已提交
1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268
		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)
1269
		retval = put_user(pid, &infop->si_pid);
L
Linus Torvalds 已提交
1270 1271
	if (!retval && infop)
		retval = put_user(p->uid, &infop->si_uid);
1272
	if (!retval)
1273
		retval = pid;
1274 1275

	if (traced) {
L
Linus Torvalds 已提交
1276
		write_lock_irq(&tasklist_lock);
1277 1278 1279 1280 1281 1282 1283 1284 1285
		/* We dropped tasklist, ptracer could die and untrace */
		ptrace_unlink(p);
		/*
		 * 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);
L
Linus Torvalds 已提交
1286
			if (p->exit_signal != -1) {
1287 1288
				p->exit_state = EXIT_ZOMBIE;
				p = NULL;
L
Linus Torvalds 已提交
1289 1290 1291 1292 1293 1294
			}
		}
		write_unlock_irq(&tasklist_lock);
	}
	if (p != NULL)
		release_task(p);
1295

L
Linus Torvalds 已提交
1296 1297 1298 1299 1300 1301 1302 1303 1304
	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.
 */
1305
static int wait_task_stopped(struct task_struct *p,
1306
			     int noreap, struct siginfo __user *infop,
L
Linus Torvalds 已提交
1307 1308
			     int __user *stat_addr, struct rusage __user *ru)
{
1309 1310
	int retval, exit_code, why;
	uid_t uid = 0; /* unneeded, required by compiler */
1311
	pid_t pid;
L
Linus Torvalds 已提交
1312

1313 1314 1315 1316 1317 1318
	exit_code = 0;
	spin_lock_irq(&p->sighand->siglock);

	if (unlikely(!task_is_stopped_or_traced(p)))
		goto unlock_sig;

1319
	if (!(p->ptrace & PT_PTRACED) && p->signal->group_stop_count > 0)
L
Linus Torvalds 已提交
1320 1321 1322 1323
		/*
		 * A group stop is in progress and this is the group leader.
		 * We won't report until all threads have stopped.
		 */
1324 1325 1326 1327 1328 1329 1330 1331 1332 1333 1334 1335 1336
		goto unlock_sig;

	exit_code = p->exit_code;
	if (!exit_code)
		goto unlock_sig;

	if (!noreap)
		p->exit_code = 0;

	uid = p->uid;
unlock_sig:
	spin_unlock_irq(&p->sighand->siglock);
	if (!exit_code)
L
Linus Torvalds 已提交
1337 1338 1339 1340 1341 1342 1343 1344 1345 1346
		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);
1347
	pid = task_pid_vnr(p);
1348
	why = (p->ptrace & PT_PTRACED) ? CLD_TRAPPED : CLD_STOPPED;
L
Linus Torvalds 已提交
1349 1350
	read_unlock(&tasklist_lock);

1351
	if (unlikely(noreap))
L
Linus Torvalds 已提交
1352
		return wait_noreap_copyout(p, pid, uid,
1353
					   why, exit_code,
L
Linus Torvalds 已提交
1354 1355 1356 1357 1358 1359 1360 1361 1362 1363
					   infop, ru);

	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)
R
Roland McGrath 已提交
1364
		retval = put_user((short)why, &infop->si_code);
L
Linus Torvalds 已提交
1365 1366 1367
	if (!retval && infop)
		retval = put_user(exit_code, &infop->si_status);
	if (!retval && infop)
1368
		retval = put_user(pid, &infop->si_pid);
L
Linus Torvalds 已提交
1369
	if (!retval && infop)
1370
		retval = put_user(uid, &infop->si_uid);
L
Linus Torvalds 已提交
1371
	if (!retval)
1372
		retval = pid;
L
Linus Torvalds 已提交
1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384
	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.
 */
1385
static int wait_task_continued(struct task_struct *p, int noreap,
L
Linus Torvalds 已提交
1386 1387 1388 1389 1390 1391 1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405
			       struct siginfo __user *infop,
			       int __user *stat_addr, struct rusage __user *ru)
{
	int retval;
	pid_t pid;
	uid_t uid;

	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);

1406
	pid = task_pid_vnr(p);
L
Linus Torvalds 已提交
1407 1408 1409 1410 1411 1412 1413 1414 1415 1416
	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)
1417
			retval = pid;
L
Linus Torvalds 已提交
1418 1419 1420 1421 1422 1423 1424 1425 1426 1427
	} else {
		retval = wait_noreap_copyout(p, pid, uid,
					     CLD_CONTINUED, SIGCONT,
					     infop, ru);
		BUG_ON(retval == 0);
	}

	return retval;
}

E
Eric W. Biederman 已提交
1428 1429 1430
static long do_wait(enum pid_type type, struct pid *pid, int options,
		    struct siginfo __user *infop, int __user *stat_addr,
		    struct rusage __user *ru)
L
Linus Torvalds 已提交
1431 1432 1433 1434 1435 1436 1437
{
	DECLARE_WAITQUEUE(wait, current);
	struct task_struct *tsk;
	int flag, retval;

	add_wait_queue(&current->signal->wait_chldexit,&wait);
repeat:
E
Eric W. Biederman 已提交
1438 1439 1440 1441 1442
	/* If there is nothing that can match our critier just get out */
	retval = -ECHILD;
	if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type])))
		goto end;

L
Linus Torvalds 已提交
1443 1444 1445 1446
	/*
	 * 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.
	 */
O
Oleg Nesterov 已提交
1447
	flag = retval = 0;
L
Linus Torvalds 已提交
1448 1449 1450 1451 1452 1453
	current->state = TASK_INTERRUPTIBLE;
	read_lock(&tasklist_lock);
	tsk = current;
	do {
		struct task_struct *p;

1454
		list_for_each_entry(p, &tsk->children, sibling) {
E
Eric W. Biederman 已提交
1455
			int ret = eligible_child(type, pid, options, p);
L
Linus Torvalds 已提交
1456 1457 1458
			if (!ret)
				continue;

1459
			if (unlikely(ret < 0)) {
O
Oleg Nesterov 已提交
1460 1461
				retval = ret;
			} else if (task_is_stopped_or_traced(p)) {
L
Linus Torvalds 已提交
1462 1463 1464 1465 1466
				/*
				 * It's stopped now, so it might later
				 * continue, exit, or stop again.
				 */
				flag = 1;
O
Oleg Nesterov 已提交
1467 1468 1469
				if (!(p->ptrace & PT_PTRACED) &&
				    !(options & WUNTRACED))
					continue;
M
Matthew Wilcox 已提交
1470

1471
				retval = wait_task_stopped(p,
M
Matthew Wilcox 已提交
1472 1473
						(options & WNOWAIT), infop,
						stat_addr, ru);
1474 1475
			} else if (p->exit_state == EXIT_ZOMBIE &&
					!delay_group_leader(p)) {
M
Matthew Wilcox 已提交
1476
				/*
1477
				 * We don't reap group leaders with subthreads.
M
Matthew Wilcox 已提交
1478 1479
				 */
				if (!likely(options & WEXITED))
L
Linus Torvalds 已提交
1480
					continue;
M
Matthew Wilcox 已提交
1481 1482 1483
				retval = wait_task_zombie(p,
						(options & WNOWAIT), infop,
						stat_addr, ru);
1484
			} else if (p->exit_state != EXIT_DEAD) {
L
Linus Torvalds 已提交
1485 1486 1487 1488 1489 1490 1491
				/*
				 * It's running now, so it might later
				 * exit, stop, or stop and then continue.
				 */
				flag = 1;
				if (!unlikely(options & WCONTINUED))
					continue;
M
Matthew Wilcox 已提交
1492 1493 1494
				retval = wait_task_continued(p,
						(options & WNOWAIT), infop,
						stat_addr, ru);
L
Linus Torvalds 已提交
1495
			}
1496 1497
			if (retval != 0) /* tasklist_lock released */
				goto end;
L
Linus Torvalds 已提交
1498 1499
		}
		if (!flag) {
1500
			list_for_each_entry(p, &tsk->ptrace_children,
O
Oleg Nesterov 已提交
1501
								ptrace_list) {
E
Eric W. Biederman 已提交
1502
				flag = eligible_child(type, pid, options, p);
O
Oleg Nesterov 已提交
1503
				if (!flag)
L
Linus Torvalds 已提交
1504
					continue;
O
Oleg Nesterov 已提交
1505 1506 1507 1508
				if (likely(flag > 0))
					break;
				retval = flag;
				goto end;
L
Linus Torvalds 已提交
1509 1510 1511 1512 1513
			}
		}
		if (options & __WNOTHREAD)
			break;
		tsk = next_thread(tsk);
E
Eric Sesterhenn 已提交
1514
		BUG_ON(tsk->signal != current->signal);
L
Linus Torvalds 已提交
1515 1516
	} while (tsk != current);
	read_unlock(&tasklist_lock);
O
Oleg Nesterov 已提交
1517

L
Linus Torvalds 已提交
1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532
	if (flag) {
		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)
1533
			retval = 0;
L
Linus Torvalds 已提交
1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548 1549 1550 1551 1552 1553 1554 1555 1556
		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;
}

E
Eric W. Biederman 已提交
1557
asmlinkage long sys_waitid(int which, pid_t upid,
L
Linus Torvalds 已提交
1558 1559 1560
			   struct siginfo __user *infop, int options,
			   struct rusage __user *ru)
{
E
Eric W. Biederman 已提交
1561 1562
	struct pid *pid = NULL;
	enum pid_type type;
L
Linus Torvalds 已提交
1563 1564 1565 1566 1567 1568 1569 1570 1571
	long ret;

	if (options & ~(WNOHANG|WNOWAIT|WEXITED|WSTOPPED|WCONTINUED))
		return -EINVAL;
	if (!(options & (WEXITED|WSTOPPED|WCONTINUED)))
		return -EINVAL;

	switch (which) {
	case P_ALL:
E
Eric W. Biederman 已提交
1572
		type = PIDTYPE_MAX;
L
Linus Torvalds 已提交
1573 1574
		break;
	case P_PID:
E
Eric W. Biederman 已提交
1575 1576
		type = PIDTYPE_PID;
		if (upid <= 0)
L
Linus Torvalds 已提交
1577 1578 1579
			return -EINVAL;
		break;
	case P_PGID:
E
Eric W. Biederman 已提交
1580 1581
		type = PIDTYPE_PGID;
		if (upid <= 0)
L
Linus Torvalds 已提交
1582 1583 1584 1585 1586 1587
			return -EINVAL;
		break;
	default:
		return -EINVAL;
	}

E
Eric W. Biederman 已提交
1588 1589 1590 1591
	if (type < PIDTYPE_MAX)
		pid = find_get_pid(upid);
	ret = do_wait(type, pid, options, infop, NULL, ru);
	put_pid(pid);
L
Linus Torvalds 已提交
1592 1593

	/* avoid REGPARM breakage on x86: */
1594
	asmlinkage_protect(5, ret, which, upid, infop, options, ru);
L
Linus Torvalds 已提交
1595 1596 1597
	return ret;
}

E
Eric W. Biederman 已提交
1598
asmlinkage long sys_wait4(pid_t upid, int __user *stat_addr,
L
Linus Torvalds 已提交
1599 1600
			  int options, struct rusage __user *ru)
{
E
Eric W. Biederman 已提交
1601 1602
	struct pid *pid = NULL;
	enum pid_type type;
L
Linus Torvalds 已提交
1603 1604 1605 1606 1607
	long ret;

	if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
			__WNOTHREAD|__WCLONE|__WALL))
		return -EINVAL;
E
Eric W. Biederman 已提交
1608 1609 1610 1611 1612 1613 1614 1615 1616 1617 1618 1619 1620 1621 1622 1623

	if (upid == -1)
		type = PIDTYPE_MAX;
	else if (upid < 0) {
		type = PIDTYPE_PGID;
		pid = find_get_pid(-upid);
	} else if (upid == 0) {
		type = PIDTYPE_PGID;
		pid = get_pid(task_pgrp(current));
	} else /* upid > 0 */ {
		type = PIDTYPE_PID;
		pid = find_get_pid(upid);
	}

	ret = do_wait(type, pid, options | WEXITED, NULL, stat_addr, ru);
	put_pid(pid);
L
Linus Torvalds 已提交
1624 1625

	/* avoid REGPARM breakage on x86: */
1626
	asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
L
Linus Torvalds 已提交
1627 1628 1629 1630 1631 1632 1633 1634 1635 1636 1637 1638 1639 1640 1641
	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