exit.c 45.7 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/iocontext.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>
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#include <linux/fdtable.h>
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#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/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 <linux/tracehook.h>
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#include <linux/init_task.h>
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#include <trace/sched.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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#include "cred-internals.h"
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DEFINE_TRACE(sched_process_free);
DEFINE_TRACE(sched_process_exit);
DEFINE_TRACE(sched_process_wait);

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static void exit_mm(struct task_struct * tsk);

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static inline int task_detached(struct task_struct *p)
{
	return p->exit_signal == -1;
}

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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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	list_del_init(&p->sibling);
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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));

	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.
		 */
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		sig->gtime = cputime_add(sig->gtime, task_gtime(tsk));
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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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		task_io_accounting_add(&sig->ioac, &tsk->ioac);
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		sig = NULL; /* Marker for below. */
	}

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	__unhash_process(tsk);

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	/*
	 * Do this under ->siglock, we can race with another thread
	 * doing sigqueue_free() if we have SIGQUEUE_PREALLOC signals.
	 */
	flush_sigqueue(&tsk->pending);

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

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	__cleanup_sighand(sighand);
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	clear_tsk_thread_flag(tsk,TIF_SIGPENDING);
	if (sig) {
		flush_sigqueue(&sig->shared_pending);
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		taskstats_tgid_free(sig);
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		/*
		 * Make sure ->signal can't go away under rq->lock,
		 * see account_group_exec_runtime().
		 */
		task_rq_unlock_wait(tsk);
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		__cleanup_signal(sig);
	}
}

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static void delayed_put_task_struct(struct rcu_head *rhp)
{
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	struct task_struct *tsk = container_of(rhp, struct task_struct, rcu);

	trace_sched_process_free(tsk);
	put_task_struct(tsk);
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}

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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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	tracehook_prepare_release_task(p);
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	/* don't need to get the RCU readlock here - the process is dead and
	 * can't be modifying its own credentials */
	atomic_dec(&__task_cred(p)->user->processes);

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	proc_flush_task(p);
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	write_lock_irq(&tasklist_lock);
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	tracehook_finish_release_task(p);
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	__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) {
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		BUG_ON(task_detached(leader));
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		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.
		 */
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		zap_leader = task_detached(leader);
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		/*
		 * This maintains the invariant that release_task()
		 * only runs on a task in EXIT_DEAD, just for sanity.
		 */
		if (zap_leader)
			leader->exit_state = EXIT_DEAD;
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	}

	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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	current->real_parent = current->parent = kthreadd_task;
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	list_move_tail(&current->sibling, &current->real_parent->children);
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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? */
	memcpy(current->signal->rlim, init_task.signal->rlim,
	       sizeof(current->signal->rlim));
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	atomic_inc(&init_cred.usage);
	commit_creds(&init_cred);
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	write_unlock_irq(&tasklist_lock);
}

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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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		change_pid(curr, PIDTYPE_SID, pid);
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		set_task_session(curr, nr);
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	}
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	if (task_pgrp(curr) != pid) {
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		change_pid(curr, PIDTYPE_PGID, pid);
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		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.
	 */
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	current->flags |= (PF_NOFREEZE | PF_KTHREAD);
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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);
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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);
583
		put_fs_struct(fs);
L
Linus Torvalds 已提交
584 585 586 587 588
	}
}

EXPORT_SYMBOL_GPL(exit_fs);

589 590 591 592 593 594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625 626 627 628 629 630 631 632 633 634 635 636 637 638 639 640 641
#ifdef CONFIG_MM_OWNER
/*
 * Task p is exiting and it owned mm, lets find a new owner for it
 */
static inline int
mm_need_new_owner(struct mm_struct *mm, struct task_struct *p)
{
	/*
	 * If there are other users of the mm and the owner (us) is exiting
	 * we need to find a new owner to take on the responsibility.
	 */
	if (atomic_read(&mm->mm_users) <= 1)
		return 0;
	if (mm->owner != p)
		return 0;
	return 1;
}

void mm_update_next_owner(struct mm_struct *mm)
{
	struct task_struct *c, *g, *p = current;

retry:
	if (!mm_need_new_owner(mm, p))
		return;

	read_lock(&tasklist_lock);
	/*
	 * Search in the children
	 */
	list_for_each_entry(c, &p->children, sibling) {
		if (c->mm == mm)
			goto assign_new_owner;
	}

	/*
	 * Search in the siblings
	 */
	list_for_each_entry(c, &p->parent->children, sibling) {
		if (c->mm == mm)
			goto assign_new_owner;
	}

	/*
	 * Search through everything else. We should not get
	 * here often
	 */
	do_each_thread(g, c) {
		if (c->mm == mm)
			goto assign_new_owner;
	} while_each_thread(g, c);

	read_unlock(&tasklist_lock);
642 643 644
	/*
	 * We found no owner yet mm_users > 1: this implies that we are
	 * most likely racing with swapoff (try_to_unuse()) or /proc or
645
	 * ptrace or page migration (get_task_mm()).  Mark owner as NULL.
646 647
	 */
	mm->owner = NULL;
648 649 650 651 652 653 654 655 656 657
	return;

assign_new_owner:
	BUG_ON(c == p);
	get_task_struct(c);
	/*
	 * The task_lock protects c->mm from changing.
	 * We always want mm->owner->mm == mm
	 */
	task_lock(c);
658 659 660 661 662
	/*
	 * Delay read_unlock() till we have the task_lock()
	 * to ensure that c does not slip away underneath us
	 */
	read_unlock(&tasklist_lock);
663 664 665 666 667 668 669 670 671 672 673
	if (c->mm != mm) {
		task_unlock(c);
		put_task_struct(c);
		goto retry;
	}
	mm->owner = c;
	task_unlock(c);
	put_task_struct(c);
}
#endif /* CONFIG_MM_OWNER */

L
Linus Torvalds 已提交
674 675 676 677
/*
 * Turn us into a lazy TLB process if we
 * aren't already..
 */
A
Adrian Bunk 已提交
678
static void exit_mm(struct task_struct * tsk)
L
Linus Torvalds 已提交
679 680
{
	struct mm_struct *mm = tsk->mm;
681
	struct core_state *core_state;
L
Linus Torvalds 已提交
682 683 684 685 686 687

	mm_release(tsk, mm);
	if (!mm)
		return;
	/*
	 * Serialize with any possible pending coredump.
688
	 * We must hold mmap_sem around checking core_state
L
Linus Torvalds 已提交
689
	 * and clearing tsk->mm.  The core-inducing thread
690
	 * will increment ->nr_threads for each thread in the
L
Linus Torvalds 已提交
691 692 693
	 * group with ->mm != NULL.
	 */
	down_read(&mm->mmap_sem);
694 695 696
	core_state = mm->core_state;
	if (core_state) {
		struct core_thread self;
L
Linus Torvalds 已提交
697
		up_read(&mm->mmap_sem);
698

699 700 701 702 703 704 705 706
		self.task = tsk;
		self.next = xchg(&core_state->dumper.next, &self);
		/*
		 * Implies mb(), the result of xchg() must be visible
		 * to core_state->dumper.
		 */
		if (atomic_dec_and_test(&core_state->nr_threads))
			complete(&core_state->startup);
L
Linus Torvalds 已提交
707

O
Oleg Nesterov 已提交
708 709 710 711 712 713 714
		for (;;) {
			set_task_state(tsk, TASK_UNINTERRUPTIBLE);
			if (!self.task) /* see coredump_finish() */
				break;
			schedule();
		}
		__set_task_state(tsk, TASK_RUNNING);
L
Linus Torvalds 已提交
715 716 717
		down_read(&mm->mmap_sem);
	}
	atomic_inc(&mm->mm_count);
E
Eric Sesterhenn 已提交
718
	BUG_ON(mm != tsk->active_mm);
L
Linus Torvalds 已提交
719 720 721 722 723
	/* more a memory barrier than a real lock */
	task_lock(tsk);
	tsk->mm = NULL;
	up_read(&mm->mmap_sem);
	enter_lazy_tlb(mm, current);
724 725
	/* We don't want this task to be frozen prematurely */
	clear_freeze_flag(tsk);
L
Linus Torvalds 已提交
726
	task_unlock(tsk);
727
	mm_update_next_owner(mm);
L
Linus Torvalds 已提交
728 729 730
	mmput(mm);
}

731 732 733 734 735 736 737 738 739 740 741 742 743 744 745 746 747
/*
 * Return nonzero if @parent's children should reap themselves.
 *
 * Called with write_lock_irq(&tasklist_lock) held.
 */
static int ignoring_children(struct task_struct *parent)
{
	int ret;
	struct sighand_struct *psig = parent->sighand;
	unsigned long flags;
	spin_lock_irqsave(&psig->siglock, flags);
	ret = (psig->action[SIGCHLD-1].sa.sa_handler == SIG_IGN ||
	       (psig->action[SIGCHLD-1].sa.sa_flags & SA_NOCLDWAIT));
	spin_unlock_irqrestore(&psig->siglock, flags);
	return ret;
}

R
Roland McGrath 已提交
748 749 750 751 752 753 754
/*
 * Detach all tasks we were using ptrace on.
 * Any that need to be release_task'd are put on the @dead list.
 *
 * Called with write_lock(&tasklist_lock) held.
 */
static void ptrace_exit(struct task_struct *parent, struct list_head *dead)
L
Linus Torvalds 已提交
755
{
R
Roland McGrath 已提交
756
	struct task_struct *p, *n;
757
	int ign = -1;
758

R
Roland McGrath 已提交
759 760 761 762 763 764 765 766 767 768 769 770 771 772
	list_for_each_entry_safe(p, n, &parent->ptraced, ptrace_entry) {
		__ptrace_unlink(p);

		if (p->exit_state != EXIT_ZOMBIE)
			continue;

		/*
		 * If it's a zombie, our attachedness prevented normal
		 * parent notification or self-reaping.  Do notification
		 * now if it would have happened earlier.  If it should
		 * reap itself, add it to the @dead list.  We can't call
		 * release_task() here because we already hold tasklist_lock.
		 *
		 * If it's our own child, there is no notification to do.
773 774
		 * But if our normal children self-reap, then this child
		 * was prevented by ptrace and we must reap it now.
L
Linus Torvalds 已提交
775
		 */
R
Roland McGrath 已提交
776 777 778
		if (!task_detached(p) && thread_group_empty(p)) {
			if (!same_thread_group(p->real_parent, parent))
				do_notify_parent(p, p->exit_signal);
779 780 781 782 783 784
			else {
				if (ign < 0)
					ign = ignoring_children(parent);
				if (ign)
					p->exit_signal = -1;
			}
R
Roland McGrath 已提交
785
		}
L
Linus Torvalds 已提交
786

R
Roland McGrath 已提交
787
		if (task_detached(p)) {
L
Linus Torvalds 已提交
788
			/*
R
Roland McGrath 已提交
789
			 * Mark it as in the process of being reaped.
L
Linus Torvalds 已提交
790
			 */
R
Roland McGrath 已提交
791 792
			p->exit_state = EXIT_DEAD;
			list_add(&p->ptrace_entry, dead);
L
Linus Torvalds 已提交
793 794
		}
	}
R
Roland McGrath 已提交
795 796 797 798 799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820 821
}

/*
 * Finish up exit-time ptrace cleanup.
 *
 * Called without locks.
 */
static void ptrace_exit_finish(struct task_struct *parent,
			       struct list_head *dead)
{
	struct task_struct *p, *n;

	BUG_ON(!list_empty(&parent->ptraced));

	list_for_each_entry_safe(p, n, dead, ptrace_entry) {
		list_del_init(&p->ptrace_entry);
		release_task(p);
	}
}

static void reparent_thread(struct task_struct *p, struct task_struct *father)
{
	if (p->pdeath_signal)
		/* We already hold the tasklist_lock here.  */
		group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);

	list_move_tail(&p->sibling, &p->real_parent->children);
L
Linus Torvalds 已提交
822

823 824 825
	/* If this is a threaded reparent there is no need to
	 * notify anyone anything has happened.
	 */
826
	if (same_thread_group(p->real_parent, father))
827 828 829
		return;

	/* We don't want people slaying init.  */
830
	if (!task_detached(p))
831 832 833 834 835
		p->exit_signal = SIGCHLD;

	/* If we'd notified the old parent about this child's death,
	 * also notify the new parent.
	 */
R
Roland McGrath 已提交
836 837
	if (!ptrace_reparented(p) &&
	    p->exit_state == EXIT_ZOMBIE &&
838
	    !task_detached(p) && thread_group_empty(p))
839 840
		do_notify_parent(p, p->exit_signal);

841
	kill_orphaned_pgrp(p, father);
L
Linus Torvalds 已提交
842 843 844 845 846 847
}

/*
 * 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
848 849
 * the child reaper process (ie "init") in our pid
 * space.
L
Linus Torvalds 已提交
850
 */
851 852 853 854 855 856 857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873 874 875 876 877 878 879 880 881 882
static struct task_struct *find_new_reaper(struct task_struct *father)
{
	struct pid_namespace *pid_ns = task_active_pid_ns(father);
	struct task_struct *thread;

	thread = father;
	while_each_thread(father, thread) {
		if (thread->flags & PF_EXITING)
			continue;
		if (unlikely(pid_ns->child_reaper == father))
			pid_ns->child_reaper = thread;
		return thread;
	}

	if (unlikely(pid_ns->child_reaper == father)) {
		write_unlock_irq(&tasklist_lock);
		if (unlikely(pid_ns == &init_pid_ns))
			panic("Attempted to kill init!");

		zap_pid_ns_processes(pid_ns);
		write_lock_irq(&tasklist_lock);
		/*
		 * We can not clear ->child_reaper or leave it alone.
		 * There may by stealth EXIT_DEAD tasks on ->children,
		 * forget_original_parent() must move them somewhere.
		 */
		pid_ns->child_reaper = init_pid_ns.child_reaper;
	}

	return pid_ns->child_reaper;
}

883
static void forget_original_parent(struct task_struct *father)
L
Linus Torvalds 已提交
884
{
885
	struct task_struct *p, *n, *reaper;
R
Roland McGrath 已提交
886
	LIST_HEAD(ptrace_dead);
887 888

	write_lock_irq(&tasklist_lock);
889
	reaper = find_new_reaper(father);
R
Roland McGrath 已提交
890 891 892 893 894
	/*
	 * First clean up ptrace if we were using it.
	 */
	ptrace_exit(father, &ptrace_dead);

895
	list_for_each_entry_safe(p, n, &father->children, sibling) {
896
		p->real_parent = reaper;
R
Roland McGrath 已提交
897 898 899 900 901
		if (p->parent == father) {
			BUG_ON(p->ptrace);
			p->parent = p->real_parent;
		}
		reparent_thread(p, father);
L
Linus Torvalds 已提交
902
	}
903 904 905 906

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

R
Roland McGrath 已提交
907
	ptrace_exit_finish(father, &ptrace_dead);
L
Linus Torvalds 已提交
908 909 910 911 912 913
}

/*
 * Send signals to all our closest relatives so that they know
 * to properly mourn us..
 */
914
static void exit_notify(struct task_struct *tsk, int group_dead)
L
Linus Torvalds 已提交
915
{
R
Roland McGrath 已提交
916 917
	int signal;
	void *cookie;
L
Linus Torvalds 已提交
918 919 920 921 922 923 924 925 926

	/*
	 * 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)
	 */
927
	forget_original_parent(tsk);
928
	exit_task_namespaces(tsk);
L
Linus Torvalds 已提交
929

930
	write_lock_irq(&tasklist_lock);
931 932
	if (group_dead)
		kill_orphaned_pgrp(tsk->group_leader, NULL);
L
Linus Torvalds 已提交
933

934
	/* Let father know we died
L
Linus Torvalds 已提交
935 936
	 *
	 * Thread signals are configurable, but you aren't going to use
937
	 * that to send signals to arbitary processes.
L
Linus Torvalds 已提交
938 939 940 941 942 943 944 945 946 947
	 * 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.
	 */
948
	if (tsk->exit_signal != SIGCHLD && !task_detached(tsk) &&
949
	    (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
950 951
	     tsk->self_exec_id != tsk->parent_exec_id) &&
	    !capable(CAP_KILL))
L
Linus Torvalds 已提交
952 953
		tsk->exit_signal = SIGCHLD;

R
Roland McGrath 已提交
954
	signal = tracehook_notify_death(tsk, &cookie, group_dead);
955
	if (signal >= 0)
R
Roland McGrath 已提交
956
		signal = do_notify_parent(tsk, signal);
L
Linus Torvalds 已提交
957

958
	tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE;
L
Linus Torvalds 已提交
959

960
	/* mt-exec, de_thread() is waiting for us */
961
	if (thread_group_leader(tsk) &&
962 963
	    tsk->signal->group_exit_task &&
	    tsk->signal->notify_count < 0)
964 965
		wake_up_process(tsk->signal->group_exit_task);

L
Linus Torvalds 已提交
966 967
	write_unlock_irq(&tasklist_lock);

R
Roland McGrath 已提交
968 969
	tracehook_report_death(tsk, signal, cookie, group_dead);

L
Linus Torvalds 已提交
970
	/* If the process is dead, release it - nobody will wait for it */
971
	if (signal == DEATH_REAP)
L
Linus Torvalds 已提交
972 973 974
		release_task(tsk);
}

975 976 977 978 979 980 981 982 983 984 985 986 987 988 989 990 991 992 993 994 995 996 997 998 999 1000 1001 1002
#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

1003
NORET_TYPE void do_exit(long code)
L
Linus Torvalds 已提交
1004 1005 1006 1007 1008 1009
{
	struct task_struct *tsk = current;
	int group_dead;

	profile_task_exit(tsk);

1010 1011
	WARN_ON(atomic_read(&tsk->fs_excl));

L
Linus Torvalds 已提交
1012 1013 1014 1015 1016
	if (unlikely(in_interrupt()))
		panic("Aiee, killing interrupt handler!");
	if (unlikely(!tsk->pid))
		panic("Attempted to kill the idle task!");

R
Roland McGrath 已提交
1017
	tracehook_report_exit(&code);
L
Linus Torvalds 已提交
1018

1019 1020 1021 1022 1023 1024 1025
	/*
	 * 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");
1026 1027 1028 1029 1030 1031 1032 1033 1034 1035
		/*
		 * 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;
1036 1037 1038 1039
		set_current_state(TASK_UNINTERRUPTIBLE);
		schedule();
	}

O
Oleg Nesterov 已提交
1040
	exit_signals(tsk);  /* sets PF_EXITING */
1041 1042 1043 1044
	/*
	 * tsk->flags are checked in the futex code to protect against
	 * an exiting task cleaning up the robust pi futexes.
	 */
1045 1046
	smp_mb();
	spin_unlock_wait(&tsk->pi_lock);
L
Linus Torvalds 已提交
1047 1048 1049

	if (unlikely(in_atomic()))
		printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
1050
				current->comm, task_pid_nr(current),
L
Linus Torvalds 已提交
1051 1052 1053
				preempt_count());

	acct_update_integrals(tsk);
1054 1055 1056 1057
	if (tsk->mm) {
		update_hiwater_rss(tsk->mm);
		update_hiwater_vm(tsk->mm);
	}
L
Linus Torvalds 已提交
1058
	group_dead = atomic_dec_and_test(&tsk->signal->live);
1059
	if (group_dead) {
1060
		hrtimer_cancel(&tsk->signal->real_timer);
1061
		exit_itimers(tsk->signal);
1062
	}
1063
	acct_collect(code, group_dead);
M
Miloslav Trmac 已提交
1064 1065
	if (group_dead)
		tty_audit_exit();
1066 1067
	if (unlikely(tsk->audit_context))
		audit_free(tsk);
1068

1069
	tsk->exit_code = code;
1070
	taskstats_exit(tsk, group_dead);
1071

L
Linus Torvalds 已提交
1072 1073
	exit_mm(tsk);

1074
	if (group_dead)
1075
		acct_process();
1076 1077
	trace_sched_process_exit(tsk);

L
Linus Torvalds 已提交
1078
	exit_sem(tsk);
1079 1080
	exit_files(tsk);
	exit_fs(tsk);
1081
	check_stack_usage();
L
Linus Torvalds 已提交
1082
	exit_thread();
1083
	cgroup_exit(tsk, 1);
L
Linus Torvalds 已提交
1084 1085 1086 1087

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

A
Al Viro 已提交
1088
	module_put(task_thread_info(tsk)->exec_domain->module);
L
Linus Torvalds 已提交
1089 1090 1091
	if (tsk->binfmt)
		module_put(tsk->binfmt->module);

M
Matt Helsley 已提交
1092
	proc_exit_connector(tsk);
1093
	exit_notify(tsk, group_dead);
L
Linus Torvalds 已提交
1094
#ifdef CONFIG_NUMA
1095
	mpol_put(tsk->mempolicy);
L
Linus Torvalds 已提交
1096 1097
	tsk->mempolicy = NULL;
#endif
1098
#ifdef CONFIG_FUTEX
1099 1100 1101 1102 1103 1104 1105 1106
	/*
	 * 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);
1107
#endif
1108
	/*
1109
	 * Make sure we are holding no locks:
1110
	 */
1111
	debug_check_no_locks_held(tsk);
1112 1113 1114 1115 1116 1117
	/*
	 * 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
1118

1119 1120 1121
	if (tsk->io_context)
		exit_io_context();

1122 1123 1124
	if (tsk->splice_pipe)
		__free_pipe_info(tsk->splice_pipe);

C
Coywolf Qi Hunt 已提交
1125
	preempt_disable();
O
Oleg Nesterov 已提交
1126
	/* causes final put_task_struct in finish_task_switch(). */
1127
	tsk->state = TASK_DEAD;
L
Linus Torvalds 已提交
1128 1129 1130
	schedule();
	BUG();
	/* Avoid "noreturn function does return".  */
A
Alan Cox 已提交
1131 1132
	for (;;)
		cpu_relax();	/* For when BUG is null */
L
Linus Torvalds 已提交
1133 1134
}

1135 1136
EXPORT_SYMBOL_GPL(do_exit);

L
Linus Torvalds 已提交
1137 1138 1139 1140
NORET_TYPE void complete_and_exit(struct completion *comp, long code)
{
	if (comp)
		complete(comp);
O
Oleg Nesterov 已提交
1141

L
Linus Torvalds 已提交
1142 1143 1144 1145 1146 1147 1148 1149 1150 1151 1152 1153 1154 1155 1156 1157 1158
	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)
{
1159 1160
	struct signal_struct *sig = current->signal;

L
Linus Torvalds 已提交
1161 1162
	BUG_ON(exit_code & 0x80); /* core dumps don't get here */

1163 1164
	if (signal_group_exit(sig))
		exit_code = sig->group_exit_code;
L
Linus Torvalds 已提交
1165 1166 1167
	else if (!thread_group_empty(current)) {
		struct sighand_struct *const sighand = current->sighand;
		spin_lock_irq(&sighand->siglock);
1168
		if (signal_group_exit(sig))
L
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1169 1170 1171 1172
			/* Another thread got here before we took the lock.  */
			exit_code = sig->group_exit_code;
		else {
			sig->group_exit_code = exit_code;
1173
			sig->flags = SIGNAL_GROUP_EXIT;
L
Linus Torvalds 已提交
1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192
			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
1193 1194 1195 1196 1197 1198 1199 1200 1201 1202 1203 1204
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
1205
{
1206 1207
	int err;

E
Eric W. Biederman 已提交
1208 1209
	if (type < PIDTYPE_MAX) {
		if (task_pid_type(p, type) != pid)
L
Linus Torvalds 已提交
1210 1211 1212 1213 1214 1215 1216 1217 1218 1219 1220 1221
			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;

1222
	err = security_task_wait(p);
1223 1224
	if (err)
		return err;
L
Linus Torvalds 已提交
1225

1226
	return 1;
L
Linus Torvalds 已提交
1227 1228
}

1229
static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
L
Linus Torvalds 已提交
1230 1231 1232 1233 1234
			       int why, int status,
			       struct siginfo __user *infop,
			       struct rusage __user *rusagep)
{
	int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1235

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
	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.
 */
R
Roland McGrath 已提交
1260
static int wait_task_zombie(struct task_struct *p, int options,
L
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1261 1262 1263 1264
			    struct siginfo __user *infop,
			    int __user *stat_addr, struct rusage __user *ru)
{
	unsigned long state;
1265
	int retval, status, traced;
1266
	pid_t pid = task_pid_vnr(p);
1267
	uid_t uid = __task_cred(p)->uid;
L
Linus Torvalds 已提交
1268

R
Roland McGrath 已提交
1269 1270 1271 1272
	if (!likely(options & WEXITED))
		return 0;

	if (unlikely(options & WNOWAIT)) {
L
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1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288 1289 1290 1291 1292 1293 1294 1295 1296 1297 1298
		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;
	}

1299
	traced = ptrace_reparented(p);
1300 1301

	if (likely(!traced)) {
1302 1303
		struct signal_struct *psig;
		struct signal_struct *sig;
1304
		struct task_cputime cputime;
1305

L
Linus Torvalds 已提交
1306 1307 1308 1309 1310 1311 1312 1313 1314 1315 1316 1317 1318 1319
		/*
		 * 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.
1320 1321 1322 1323
		 *
		 * We use thread_group_cputime() to get times for the thread
		 * group, which consolidates times for all threads in the
		 * group including the group leader.
L
Linus Torvalds 已提交
1324
		 */
1325
		thread_group_cputime(p, &cputime);
L
Linus Torvalds 已提交
1326
		spin_lock_irq(&p->parent->sighand->siglock);
1327 1328 1329 1330
		psig = p->parent->signal;
		sig = p->signal;
		psig->cutime =
			cputime_add(psig->cutime,
1331 1332
			cputime_add(cputime.utime,
				    sig->cutime));
1333 1334
		psig->cstime =
			cputime_add(psig->cstime,
1335 1336
			cputime_add(cputime.stime,
				    sig->cstime));
1337 1338 1339 1340 1341
		psig->cgtime =
			cputime_add(psig->cgtime,
			cputime_add(p->gtime,
			cputime_add(sig->gtime,
				    sig->cgtime)));
1342 1343 1344 1345 1346 1347 1348 1349
		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;
1350 1351 1352 1353 1354 1355
		psig->cinblock +=
			task_io_get_inblock(p) +
			sig->inblock + sig->cinblock;
		psig->coublock +=
			task_io_get_oublock(p) +
			sig->oublock + sig->coublock;
1356 1357
		task_io_accounting_add(&psig->ioac, &p->ioac);
		task_io_accounting_add(&psig->ioac, &sig->ioac);
L
Linus Torvalds 已提交
1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381 1382 1383 1384 1385 1386 1387 1388 1389 1390
		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)
1391
		retval = put_user(pid, &infop->si_pid);
L
Linus Torvalds 已提交
1392
	if (!retval && infop)
1393
		retval = put_user(uid, &infop->si_uid);
1394
	if (!retval)
1395
		retval = pid;
1396 1397

	if (traced) {
L
Linus Torvalds 已提交
1398
		write_lock_irq(&tasklist_lock);
1399 1400 1401 1402 1403 1404 1405
		/* 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.
		 */
1406
		if (!task_detached(p)) {
1407
			do_notify_parent(p, p->exit_signal);
1408
			if (!task_detached(p)) {
1409 1410
				p->exit_state = EXIT_ZOMBIE;
				p = NULL;
L
Linus Torvalds 已提交
1411 1412 1413 1414 1415 1416
			}
		}
		write_unlock_irq(&tasklist_lock);
	}
	if (p != NULL)
		release_task(p);
1417

L
Linus Torvalds 已提交
1418 1419 1420 1421 1422 1423 1424 1425 1426
	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.
 */
R
Roland McGrath 已提交
1427
static int wait_task_stopped(int ptrace, struct task_struct *p,
R
Roland McGrath 已提交
1428
			     int options, struct siginfo __user *infop,
L
Linus Torvalds 已提交
1429 1430
			     int __user *stat_addr, struct rusage __user *ru)
{
1431 1432
	int retval, exit_code, why;
	uid_t uid = 0; /* unneeded, required by compiler */
1433
	pid_t pid;
L
Linus Torvalds 已提交
1434

R
Roland McGrath 已提交
1435
	if (!(options & WUNTRACED))
R
Roland McGrath 已提交
1436 1437
		return 0;

1438 1439 1440 1441 1442 1443
	exit_code = 0;
	spin_lock_irq(&p->sighand->siglock);

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

R
Roland McGrath 已提交
1444
	if (!ptrace && p->signal->group_stop_count > 0)
L
Linus Torvalds 已提交
1445 1446 1447 1448
		/*
		 * A group stop is in progress and this is the group leader.
		 * We won't report until all threads have stopped.
		 */
1449 1450 1451 1452 1453 1454
		goto unlock_sig;

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

R
Roland McGrath 已提交
1455
	if (!unlikely(options & WNOWAIT))
1456 1457
		p->exit_code = 0;

1458 1459
	/* don't need the RCU readlock here as we're holding a spinlock */
	uid = __task_cred(p)->uid;
1460 1461 1462
unlock_sig:
	spin_unlock_irq(&p->sighand->siglock);
	if (!exit_code)
L
Linus Torvalds 已提交
1463 1464 1465 1466 1467 1468 1469 1470 1471 1472
		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);
1473
	pid = task_pid_vnr(p);
R
Roland McGrath 已提交
1474
	why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
L
Linus Torvalds 已提交
1475 1476
	read_unlock(&tasklist_lock);

R
Roland McGrath 已提交
1477
	if (unlikely(options & WNOWAIT))
L
Linus Torvalds 已提交
1478
		return wait_noreap_copyout(p, pid, uid,
1479
					   why, exit_code,
L
Linus Torvalds 已提交
1480 1481 1482 1483 1484 1485 1486 1487 1488 1489
					   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
1490
		retval = put_user((short)why, &infop->si_code);
L
Linus Torvalds 已提交
1491 1492 1493
	if (!retval && infop)
		retval = put_user(exit_code, &infop->si_status);
	if (!retval && infop)
1494
		retval = put_user(pid, &infop->si_pid);
L
Linus Torvalds 已提交
1495
	if (!retval && infop)
1496
		retval = put_user(uid, &infop->si_uid);
L
Linus Torvalds 已提交
1497
	if (!retval)
1498
		retval = pid;
L
Linus Torvalds 已提交
1499 1500 1501 1502 1503 1504 1505 1506 1507 1508 1509 1510
	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.
 */
R
Roland McGrath 已提交
1511
static int wait_task_continued(struct task_struct *p, int options,
L
Linus Torvalds 已提交
1512 1513 1514 1515 1516 1517 1518
			       struct siginfo __user *infop,
			       int __user *stat_addr, struct rusage __user *ru)
{
	int retval;
	pid_t pid;
	uid_t uid;

R
Roland McGrath 已提交
1519 1520 1521
	if (!unlikely(options & WCONTINUED))
		return 0;

L
Linus Torvalds 已提交
1522 1523 1524 1525 1526 1527 1528 1529 1530
	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;
	}
R
Roland McGrath 已提交
1531
	if (!unlikely(options & WNOWAIT))
L
Linus Torvalds 已提交
1532
		p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1533
	uid = __task_cred(p)->uid;
L
Linus Torvalds 已提交
1534 1535
	spin_unlock_irq(&p->sighand->siglock);

1536
	pid = task_pid_vnr(p);
L
Linus Torvalds 已提交
1537 1538 1539 1540 1541 1542 1543 1544 1545
	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)
1546
			retval = pid;
L
Linus Torvalds 已提交
1547 1548 1549 1550 1551 1552 1553 1554 1555 1556
	} else {
		retval = wait_noreap_copyout(p, pid, uid,
					     CLD_CONTINUED, SIGCONT,
					     infop, ru);
		BUG_ON(retval == 0);
	}

	return retval;
}

R
Roland McGrath 已提交
1557 1558 1559 1560 1561 1562
/*
 * Consider @p for a wait by @parent.
 *
 * -ECHILD should be in *@notask_error before the first call.
 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
 * Returns zero if the search for a child should continue;
1563 1564
 * then *@notask_error is 0 if @p is an eligible child,
 * or another error from security_task_wait(), or still -ECHILD.
R
Roland McGrath 已提交
1565
 */
R
Roland McGrath 已提交
1566
static int wait_consider_task(struct task_struct *parent, int ptrace,
R
Roland McGrath 已提交
1567 1568 1569 1570 1571 1572
			      struct task_struct *p, int *notask_error,
			      enum pid_type type, struct pid *pid, int options,
			      struct siginfo __user *infop,
			      int __user *stat_addr, struct rusage __user *ru)
{
	int ret = eligible_child(type, pid, options, p);
1573
	if (!ret)
R
Roland McGrath 已提交
1574 1575
		return ret;

1576 1577 1578 1579 1580 1581 1582 1583 1584 1585 1586 1587
	if (unlikely(ret < 0)) {
		/*
		 * If we have not yet seen any eligible child,
		 * then let this error code replace -ECHILD.
		 * A permission error will give the user a clue
		 * to look for security policy problems, rather
		 * than for mysterious wait bugs.
		 */
		if (*notask_error)
			*notask_error = ret;
	}

R
Roland McGrath 已提交
1588 1589 1590 1591 1592 1593 1594 1595 1596
	if (likely(!ptrace) && unlikely(p->ptrace)) {
		/*
		 * This child is hidden by ptrace.
		 * We aren't allowed to see it now, but eventually we will.
		 */
		*notask_error = 0;
		return 0;
	}

R
Roland McGrath 已提交
1597 1598 1599 1600 1601 1602 1603 1604 1605 1606 1607 1608 1609 1610 1611 1612
	if (p->exit_state == EXIT_DEAD)
		return 0;

	/*
	 * We don't reap group leaders with subthreads.
	 */
	if (p->exit_state == EXIT_ZOMBIE && !delay_group_leader(p))
		return wait_task_zombie(p, options, infop, stat_addr, ru);

	/*
	 * It's stopped or running now, so it might
	 * later continue, exit, or stop again.
	 */
	*notask_error = 0;

	if (task_is_stopped_or_traced(p))
R
Roland McGrath 已提交
1613 1614
		return wait_task_stopped(ptrace, p, options,
					 infop, stat_addr, ru);
R
Roland McGrath 已提交
1615 1616 1617 1618 1619 1620 1621 1622 1623 1624

	return wait_task_continued(p, options, infop, stat_addr, ru);
}

/*
 * Do the work of do_wait() for one thread in the group, @tsk.
 *
 * -ECHILD should be in *@notask_error before the first call.
 * Returns nonzero for a final return, when we have unlocked tasklist_lock.
 * Returns zero if the search for a child should continue; then
1625 1626
 * *@notask_error is 0 if there were any eligible children,
 * or another error from security_task_wait(), or still -ECHILD.
R
Roland McGrath 已提交
1627 1628 1629 1630 1631 1632 1633 1634 1635
 */
static int do_wait_thread(struct task_struct *tsk, int *notask_error,
			  enum pid_type type, struct pid *pid, int options,
			  struct siginfo __user *infop, int __user *stat_addr,
			  struct rusage __user *ru)
{
	struct task_struct *p;

	list_for_each_entry(p, &tsk->children, sibling) {
R
Roland McGrath 已提交
1636 1637 1638 1639 1640 1641 1642 1643 1644 1645
		/*
		 * Do not consider detached threads.
		 */
		if (!task_detached(p)) {
			int ret = wait_consider_task(tsk, 0, p, notask_error,
						     type, pid, options,
						     infop, stat_addr, ru);
			if (ret)
				return ret;
		}
R
Roland McGrath 已提交
1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658
	}

	return 0;
}

static int ptrace_do_wait(struct task_struct *tsk, int *notask_error,
			  enum pid_type type, struct pid *pid, int options,
			  struct siginfo __user *infop, int __user *stat_addr,
			  struct rusage __user *ru)
{
	struct task_struct *p;

	/*
R
Roland McGrath 已提交
1659
	 * Traditionally we see ptrace'd stopped tasks regardless of options.
R
Roland McGrath 已提交
1660
	 */
R
Roland McGrath 已提交
1661
	options |= WUNTRACED;
R
Roland McGrath 已提交
1662

R
Roland McGrath 已提交
1663 1664 1665 1666 1667
	list_for_each_entry(p, &tsk->ptraced, ptrace_entry) {
		int ret = wait_consider_task(tsk, 1, p, notask_error,
					     type, pid, options,
					     infop, stat_addr, ru);
		if (ret)
R
Roland McGrath 已提交
1668 1669 1670 1671 1672 1673
			return ret;
	}

	return 0;
}

E
Eric W. Biederman 已提交
1674 1675 1676
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
1677 1678 1679
{
	DECLARE_WAITQUEUE(wait, current);
	struct task_struct *tsk;
R
Roland McGrath 已提交
1680
	int retval;
L
Linus Torvalds 已提交
1681

1682 1683
	trace_sched_process_wait(pid);

L
Linus Torvalds 已提交
1684 1685
	add_wait_queue(&current->signal->wait_chldexit,&wait);
repeat:
R
Roland McGrath 已提交
1686 1687 1688 1689 1690
	/*
	 * If there is nothing that can match our critiera just get out.
	 * We will clear @retval to zero if we see any child that might later
	 * match our criteria, even if we are not able to reap it yet.
	 */
E
Eric W. Biederman 已提交
1691 1692 1693 1694
	retval = -ECHILD;
	if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type])))
		goto end;

L
Linus Torvalds 已提交
1695 1696 1697 1698
	current->state = TASK_INTERRUPTIBLE;
	read_lock(&tasklist_lock);
	tsk = current;
	do {
R
Roland McGrath 已提交
1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711
		int tsk_result = do_wait_thread(tsk, &retval,
						type, pid, options,
						infop, stat_addr, ru);
		if (!tsk_result)
			tsk_result = ptrace_do_wait(tsk, &retval,
						    type, pid, options,
						    infop, stat_addr, ru);
		if (tsk_result) {
			/*
			 * tasklist_lock is unlocked and we have a final result.
			 */
			retval = tsk_result;
			goto end;
L
Linus Torvalds 已提交
1712
		}
R
Roland McGrath 已提交
1713

L
Linus Torvalds 已提交
1714 1715 1716
		if (options & __WNOTHREAD)
			break;
		tsk = next_thread(tsk);
E
Eric Sesterhenn 已提交
1717
		BUG_ON(tsk->signal != current->signal);
L
Linus Torvalds 已提交
1718 1719
	} while (tsk != current);
	read_unlock(&tasklist_lock);
O
Oleg Nesterov 已提交
1720

R
Roland McGrath 已提交
1721
	if (!retval && !(options & WNOHANG)) {
L
Linus Torvalds 已提交
1722
		retval = -ERESTARTSYS;
R
Roland McGrath 已提交
1723 1724 1725 1726
		if (!signal_pending(current)) {
			schedule();
			goto repeat;
		}
L
Linus Torvalds 已提交
1727
	}
R
Roland McGrath 已提交
1728

L
Linus Torvalds 已提交
1729 1730 1731 1732 1733
end:
	current->state = TASK_RUNNING;
	remove_wait_queue(&current->signal->wait_chldexit,&wait);
	if (infop) {
		if (retval > 0)
1734
			retval = 0;
L
Linus Torvalds 已提交
1735 1736 1737 1738 1739 1740 1741 1742 1743 1744 1745 1746 1747 1748 1749 1750 1751 1752 1753 1754 1755 1756 1757
		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
1758
asmlinkage long sys_waitid(int which, pid_t upid,
L
Linus Torvalds 已提交
1759 1760 1761
			   struct siginfo __user *infop, int options,
			   struct rusage __user *ru)
{
E
Eric W. Biederman 已提交
1762 1763
	struct pid *pid = NULL;
	enum pid_type type;
L
Linus Torvalds 已提交
1764 1765 1766 1767 1768 1769 1770 1771 1772
	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
1773
		type = PIDTYPE_MAX;
L
Linus Torvalds 已提交
1774 1775
		break;
	case P_PID:
E
Eric W. Biederman 已提交
1776 1777
		type = PIDTYPE_PID;
		if (upid <= 0)
L
Linus Torvalds 已提交
1778 1779 1780
			return -EINVAL;
		break;
	case P_PGID:
E
Eric W. Biederman 已提交
1781 1782
		type = PIDTYPE_PGID;
		if (upid <= 0)
L
Linus Torvalds 已提交
1783 1784 1785 1786 1787 1788
			return -EINVAL;
		break;
	default:
		return -EINVAL;
	}

E
Eric W. Biederman 已提交
1789 1790 1791 1792
	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
1793 1794

	/* avoid REGPARM breakage on x86: */
1795
	asmlinkage_protect(5, ret, which, upid, infop, options, ru);
L
Linus Torvalds 已提交
1796 1797 1798
	return ret;
}

E
Eric W. Biederman 已提交
1799
asmlinkage long sys_wait4(pid_t upid, int __user *stat_addr,
L
Linus Torvalds 已提交
1800 1801
			  int options, struct rusage __user *ru)
{
E
Eric W. Biederman 已提交
1802 1803
	struct pid *pid = NULL;
	enum pid_type type;
L
Linus Torvalds 已提交
1804 1805 1806 1807 1808
	long ret;

	if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
			__WNOTHREAD|__WCLONE|__WALL))
		return -EINVAL;
E
Eric W. Biederman 已提交
1809 1810 1811 1812 1813 1814 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824

	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
1825 1826

	/* avoid REGPARM breakage on x86: */
1827
	asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
L
Linus Torvalds 已提交
1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842
	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