exit.c 43.5 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/fs_struct.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 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->utime = cputime_add(sig->utime, task_utime(tsk));
		sig->stime = cputime_add(sig->stime, task_stime(tsk));
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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->sum_sched_runtime += tsk->se.sum_exec_runtime;
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		sig = NULL; /* Marker for below. */
	}

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	/*
	 * Flush inherited counters to the parent - before the parent
	 * gets woken up by child-exit notifications.
	 */
	perf_counter_exit_task(tsk);

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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);

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#ifdef CONFIG_PERF_COUNTERS
	WARN_ON_ONCE(!list_empty(&tsk->perf_counter_ctx.counter_list));
#endif
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	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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	if (task_session(curr) != pid)
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		change_pid(curr, PIDTYPE_SID, pid);
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	if (task_pgrp(curr) != pid)
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		change_pid(curr, PIDTYPE_PGID, pid);
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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;
	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 */

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	daemonize_fs_struct();
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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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#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);
617 618 619
	/*
	 * We found no owner yet mm_users > 1: this implies that we are
	 * most likely racing with swapoff (try_to_unuse()) or /proc or
620
	 * ptrace or page migration (get_task_mm()).  Mark owner as NULL.
621 622
	 */
	mm->owner = NULL;
623 624 625 626 627 628 629 630 631 632
	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);
633 634 635 636 637
	/*
	 * Delay read_unlock() till we have the task_lock()
	 * to ensure that c does not slip away underneath us
	 */
	read_unlock(&tasklist_lock);
638 639 640 641 642 643 644 645 646 647 648
	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
649 650 651 652
/*
 * Turn us into a lazy TLB process if we
 * aren't already..
 */
A
Adrian Bunk 已提交
653
static void exit_mm(struct task_struct * tsk)
L
Linus Torvalds 已提交
654 655
{
	struct mm_struct *mm = tsk->mm;
656
	struct core_state *core_state;
L
Linus Torvalds 已提交
657 658 659 660 661 662

	mm_release(tsk, mm);
	if (!mm)
		return;
	/*
	 * Serialize with any possible pending coredump.
663
	 * We must hold mmap_sem around checking core_state
L
Linus Torvalds 已提交
664
	 * and clearing tsk->mm.  The core-inducing thread
665
	 * will increment ->nr_threads for each thread in the
L
Linus Torvalds 已提交
666 667 668
	 * group with ->mm != NULL.
	 */
	down_read(&mm->mmap_sem);
669 670 671
	core_state = mm->core_state;
	if (core_state) {
		struct core_thread self;
L
Linus Torvalds 已提交
672
		up_read(&mm->mmap_sem);
673

674 675 676 677 678 679 680 681
		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
682

O
Oleg Nesterov 已提交
683 684 685 686 687 688 689
		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
690 691 692
		down_read(&mm->mmap_sem);
	}
	atomic_inc(&mm->mm_count);
E
Eric Sesterhenn 已提交
693
	BUG_ON(mm != tsk->active_mm);
L
Linus Torvalds 已提交
694 695 696 697 698
	/* more a memory barrier than a real lock */
	task_lock(tsk);
	tsk->mm = NULL;
	up_read(&mm->mmap_sem);
	enter_lazy_tlb(mm, current);
699 700
	/* We don't want this task to be frozen prematurely */
	clear_freeze_flag(tsk);
L
Linus Torvalds 已提交
701
	task_unlock(tsk);
702
	mm_update_next_owner(mm);
L
Linus Torvalds 已提交
703 704 705 706 707 708 709
	mmput(mm);
}

/*
 * 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
710 711
 * the child reaper process (ie "init") in our pid
 * space.
L
Linus Torvalds 已提交
712
 */
713 714 715 716 717 718 719 720 721 722 723 724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740 741 742 743 744
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;
}

745 746 747 748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765 766 767 768 769 770 771 772 773 774 775 776 777 778 779 780
/*
* Any that need to be release_task'd are put on the @dead list.
 */
static void reparent_thread(struct task_struct *father, struct task_struct *p,
				struct list_head *dead)
{
	if (p->pdeath_signal)
		group_send_sig_info(p->pdeath_signal, SEND_SIG_NOINFO, p);

	list_move_tail(&p->sibling, &p->real_parent->children);

	if (task_detached(p))
		return;
	/*
	 * If this is a threaded reparent there is no need to
	 * notify anyone anything has happened.
	 */
	if (same_thread_group(p->real_parent, father))
		return;

	/* We don't want people slaying init.  */
	p->exit_signal = SIGCHLD;

	/* If it has exited notify the new parent about this child's death. */
	if (!p->ptrace &&
	    p->exit_state == EXIT_ZOMBIE && thread_group_empty(p)) {
		do_notify_parent(p, p->exit_signal);
		if (task_detached(p)) {
			p->exit_state = EXIT_DEAD;
			list_move_tail(&p->sibling, dead);
		}
	}

	kill_orphaned_pgrp(p, father);
}

781
static void forget_original_parent(struct task_struct *father)
L
Linus Torvalds 已提交
782
{
783
	struct task_struct *p, *n, *reaper;
784
	LIST_HEAD(dead_children);
785

786
	exit_ptrace(father);
787 788

	write_lock_irq(&tasklist_lock);
789
	reaper = find_new_reaper(father);
R
Roland McGrath 已提交
790

791
	list_for_each_entry_safe(p, n, &father->children, sibling) {
792
		p->real_parent = reaper;
R
Roland McGrath 已提交
793 794 795 796
		if (p->parent == father) {
			BUG_ON(p->ptrace);
			p->parent = p->real_parent;
		}
797
		reparent_thread(father, p, &dead_children);
L
Linus Torvalds 已提交
798
	}
799
	write_unlock_irq(&tasklist_lock);
800

801 802
	BUG_ON(!list_empty(&father->children));

803 804
	list_for_each_entry_safe(p, n, &dead_children, sibling) {
		list_del_init(&p->sibling);
805 806
		release_task(p);
	}
L
Linus Torvalds 已提交
807 808 809 810 811 812
}

/*
 * Send signals to all our closest relatives so that they know
 * to properly mourn us..
 */
813
static void exit_notify(struct task_struct *tsk, int group_dead)
L
Linus Torvalds 已提交
814
{
R
Roland McGrath 已提交
815 816
	int signal;
	void *cookie;
L
Linus Torvalds 已提交
817 818 819 820 821 822 823 824 825

	/*
	 * 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)
	 */
826
	forget_original_parent(tsk);
827
	exit_task_namespaces(tsk);
L
Linus Torvalds 已提交
828

829
	write_lock_irq(&tasklist_lock);
830 831
	if (group_dead)
		kill_orphaned_pgrp(tsk->group_leader, NULL);
L
Linus Torvalds 已提交
832

833
	/* Let father know we died
L
Linus Torvalds 已提交
834 835
	 *
	 * Thread signals are configurable, but you aren't going to use
836
	 * that to send signals to arbitary processes.
L
Linus Torvalds 已提交
837 838 839 840 841 842 843 844 845 846
	 * 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.
	 */
847
	if (tsk->exit_signal != SIGCHLD && !task_detached(tsk) &&
848
	    (tsk->parent_exec_id != tsk->real_parent->self_exec_id ||
849
	     tsk->self_exec_id != tsk->parent_exec_id))
L
Linus Torvalds 已提交
850 851
		tsk->exit_signal = SIGCHLD;

R
Roland McGrath 已提交
852
	signal = tracehook_notify_death(tsk, &cookie, group_dead);
853
	if (signal >= 0)
R
Roland McGrath 已提交
854
		signal = do_notify_parent(tsk, signal);
L
Linus Torvalds 已提交
855

856
	tsk->exit_state = signal == DEATH_REAP ? EXIT_DEAD : EXIT_ZOMBIE;
L
Linus Torvalds 已提交
857

858
	/* mt-exec, de_thread() is waiting for us */
859
	if (thread_group_leader(tsk) &&
860 861
	    tsk->signal->group_exit_task &&
	    tsk->signal->notify_count < 0)
862 863
		wake_up_process(tsk->signal->group_exit_task);

L
Linus Torvalds 已提交
864 865
	write_unlock_irq(&tasklist_lock);

R
Roland McGrath 已提交
866 867
	tracehook_report_death(tsk, signal, cookie, group_dead);

L
Linus Torvalds 已提交
868
	/* If the process is dead, release it - nobody will wait for it */
869
	if (signal == DEATH_REAP)
L
Linus Torvalds 已提交
870 871 872
		release_task(tsk);
}

873 874 875 876 877 878 879
#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 free;

880
	free = stack_not_used(current);
881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897

	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

898
NORET_TYPE void do_exit(long code)
L
Linus Torvalds 已提交
899 900 901 902 903 904
{
	struct task_struct *tsk = current;
	int group_dead;

	profile_task_exit(tsk);

905 906
	WARN_ON(atomic_read(&tsk->fs_excl));

L
Linus Torvalds 已提交
907 908 909 910 911
	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
912
	tracehook_report_exit(&code);
L
Linus Torvalds 已提交
913

914 915 916 917 918 919 920
	/*
	 * 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");
921 922 923 924 925 926 927 928 929 930
		/*
		 * 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;
931 932 933 934
		set_current_state(TASK_UNINTERRUPTIBLE);
		schedule();
	}

935 936
	exit_irq_thread();

O
Oleg Nesterov 已提交
937
	exit_signals(tsk);  /* sets PF_EXITING */
938 939 940 941
	/*
	 * tsk->flags are checked in the futex code to protect against
	 * an exiting task cleaning up the robust pi futexes.
	 */
942 943
	smp_mb();
	spin_unlock_wait(&tsk->pi_lock);
L
Linus Torvalds 已提交
944 945 946

	if (unlikely(in_atomic()))
		printk(KERN_INFO "note: %s[%d] exited with preempt_count %d\n",
947
				current->comm, task_pid_nr(current),
L
Linus Torvalds 已提交
948 949 950
				preempt_count());

	acct_update_integrals(tsk);
951

L
Linus Torvalds 已提交
952
	group_dead = atomic_dec_and_test(&tsk->signal->live);
953
	if (group_dead) {
954
		hrtimer_cancel(&tsk->signal->real_timer);
955
		exit_itimers(tsk->signal);
956
	}
957
	acct_collect(code, group_dead);
M
Miloslav Trmac 已提交
958 959
	if (group_dead)
		tty_audit_exit();
960 961
	if (unlikely(tsk->audit_context))
		audit_free(tsk);
962

963
	tsk->exit_code = code;
964
	taskstats_exit(tsk, group_dead);
965

L
Linus Torvalds 已提交
966 967
	exit_mm(tsk);

968
	if (group_dead)
969
		acct_process();
970 971
	trace_sched_process_exit(tsk);

L
Linus Torvalds 已提交
972
	exit_sem(tsk);
973 974
	exit_files(tsk);
	exit_fs(tsk);
975
	check_stack_usage();
L
Linus Torvalds 已提交
976
	exit_thread();
977
	cgroup_exit(tsk, 1);
L
Linus Torvalds 已提交
978 979 980 981

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

A
Al Viro 已提交
982
	module_put(task_thread_info(tsk)->exec_domain->module);
L
Linus Torvalds 已提交
983 984 985
	if (tsk->binfmt)
		module_put(tsk->binfmt->module);

M
Matt Helsley 已提交
986
	proc_exit_connector(tsk);
987
	exit_notify(tsk, group_dead);
L
Linus Torvalds 已提交
988
#ifdef CONFIG_NUMA
989
	mpol_put(tsk->mempolicy);
L
Linus Torvalds 已提交
990 991
	tsk->mempolicy = NULL;
#endif
992
#ifdef CONFIG_FUTEX
993 994 995 996
	if (unlikely(!list_empty(&tsk->pi_state_list)))
		exit_pi_state_list(tsk);
	if (unlikely(current->pi_state_cache))
		kfree(current->pi_state_cache);
997
#endif
998
	/*
999
	 * Make sure we are holding no locks:
1000
	 */
1001
	debug_check_no_locks_held(tsk);
1002 1003 1004 1005 1006 1007
	/*
	 * 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
1008

1009 1010 1011
	if (tsk->io_context)
		exit_io_context();

1012 1013 1014
	if (tsk->splice_pipe)
		__free_pipe_info(tsk->splice_pipe);

C
Coywolf Qi Hunt 已提交
1015
	preempt_disable();
O
Oleg Nesterov 已提交
1016
	/* causes final put_task_struct in finish_task_switch(). */
1017
	tsk->state = TASK_DEAD;
L
Linus Torvalds 已提交
1018 1019 1020
	schedule();
	BUG();
	/* Avoid "noreturn function does return".  */
A
Alan Cox 已提交
1021 1022
	for (;;)
		cpu_relax();	/* For when BUG is null */
L
Linus Torvalds 已提交
1023 1024
}

1025 1026
EXPORT_SYMBOL_GPL(do_exit);

L
Linus Torvalds 已提交
1027 1028 1029 1030
NORET_TYPE void complete_and_exit(struct completion *comp, long code)
{
	if (comp)
		complete(comp);
O
Oleg Nesterov 已提交
1031

L
Linus Torvalds 已提交
1032 1033 1034 1035 1036
	do_exit(code);
}

EXPORT_SYMBOL(complete_and_exit);

1037
SYSCALL_DEFINE1(exit, int, error_code)
L
Linus Torvalds 已提交
1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048
{
	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)
{
1049 1050
	struct signal_struct *sig = current->signal;

L
Linus Torvalds 已提交
1051 1052
	BUG_ON(exit_code & 0x80); /* core dumps don't get here */

1053 1054
	if (signal_group_exit(sig))
		exit_code = sig->group_exit_code;
L
Linus Torvalds 已提交
1055 1056 1057
	else if (!thread_group_empty(current)) {
		struct sighand_struct *const sighand = current->sighand;
		spin_lock_irq(&sighand->siglock);
1058
		if (signal_group_exit(sig))
L
Linus Torvalds 已提交
1059 1060 1061 1062
			/* Another thread got here before we took the lock.  */
			exit_code = sig->group_exit_code;
		else {
			sig->group_exit_code = exit_code;
1063
			sig->flags = SIGNAL_GROUP_EXIT;
L
Linus Torvalds 已提交
1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077
			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.
 */
1078
SYSCALL_DEFINE1(exit_group, int, error_code)
L
Linus Torvalds 已提交
1079 1080
{
	do_group_exit((error_code & 0xff) << 8);
1081 1082
	/* NOTREACHED */
	return 0;
L
Linus Torvalds 已提交
1083 1084
}

E
Eric W. Biederman 已提交
1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096
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
1097
{
1098 1099
	int err;

E
Eric W. Biederman 已提交
1100 1101
	if (type < PIDTYPE_MAX) {
		if (task_pid_type(p, type) != pid)
L
Linus Torvalds 已提交
1102 1103 1104 1105 1106 1107 1108 1109 1110 1111 1112 1113
			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;

1114
	err = security_task_wait(p);
1115 1116
	if (err)
		return err;
L
Linus Torvalds 已提交
1117

1118
	return 1;
L
Linus Torvalds 已提交
1119 1120
}

1121
static int wait_noreap_copyout(struct task_struct *p, pid_t pid, uid_t uid,
L
Linus Torvalds 已提交
1122 1123 1124 1125 1126
			       int why, int status,
			       struct siginfo __user *infop,
			       struct rusage __user *rusagep)
{
	int retval = rusagep ? getrusage(p, RUSAGE_BOTH, rusagep) : 0;
1127

L
Linus Torvalds 已提交
1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146 1147 1148 1149 1150 1151
	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
1152
static int wait_task_zombie(struct task_struct *p, int options,
L
Linus Torvalds 已提交
1153 1154 1155 1156
			    struct siginfo __user *infop,
			    int __user *stat_addr, struct rusage __user *ru)
{
	unsigned long state;
1157
	int retval, status, traced;
1158
	pid_t pid = task_pid_vnr(p);
1159
	uid_t uid = __task_cred(p)->uid;
L
Linus Torvalds 已提交
1160

R
Roland McGrath 已提交
1161 1162 1163 1164
	if (!likely(options & WEXITED))
		return 0;

	if (unlikely(options & WNOWAIT)) {
L
Linus Torvalds 已提交
1165 1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190
		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;
	}

1191
	traced = ptrace_reparented(p);
1192 1193

	if (likely(!traced)) {
1194 1195
		struct signal_struct *psig;
		struct signal_struct *sig;
1196
		struct task_cputime cputime;
1197

L
Linus Torvalds 已提交
1198 1199 1200 1201 1202 1203 1204 1205 1206 1207 1208 1209 1210 1211
		/*
		 * 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.
1212 1213 1214 1215
		 *
		 * 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
1216
		 */
1217
		thread_group_cputime(p, &cputime);
L
Linus Torvalds 已提交
1218
		spin_lock_irq(&p->parent->sighand->siglock);
1219 1220 1221 1222
		psig = p->parent->signal;
		sig = p->signal;
		psig->cutime =
			cputime_add(psig->cutime,
1223 1224
			cputime_add(cputime.utime,
				    sig->cutime));
1225 1226
		psig->cstime =
			cputime_add(psig->cstime,
1227 1228
			cputime_add(cputime.stime,
				    sig->cstime));
1229 1230 1231 1232 1233
		psig->cgtime =
			cputime_add(psig->cgtime,
			cputime_add(p->gtime,
			cputime_add(sig->gtime,
				    sig->cgtime)));
1234 1235 1236 1237 1238 1239 1240 1241
		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;
1242 1243 1244 1245 1246 1247
		psig->cinblock +=
			task_io_get_inblock(p) +
			sig->inblock + sig->cinblock;
		psig->coublock +=
			task_io_get_oublock(p) +
			sig->oublock + sig->coublock;
1248 1249
		task_io_accounting_add(&psig->ioac, &p->ioac);
		task_io_accounting_add(&psig->ioac, &sig->ioac);
L
Linus Torvalds 已提交
1250 1251 1252 1253 1254 1255 1256 1257 1258
		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);

1259 1260 1261 1262 1263 1264
	/*
	 * Flush inherited counters to the parent - before the parent
	 * gets woken up by child-exit notifications.
	 */
	perf_counter_exit_task(p);

L
Linus Torvalds 已提交
1265 1266 1267 1268 1269 1270 1271 1272 1273 1274 1275 1276 1277 1278 1279 1280 1281 1282 1283 1284 1285 1286 1287 1288
	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)
1289
		retval = put_user(pid, &infop->si_pid);
L
Linus Torvalds 已提交
1290
	if (!retval && infop)
1291
		retval = put_user(uid, &infop->si_uid);
1292
	if (!retval)
1293
		retval = pid;
1294 1295

	if (traced) {
L
Linus Torvalds 已提交
1296
		write_lock_irq(&tasklist_lock);
1297 1298 1299 1300 1301 1302 1303
		/* 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.
		 */
1304
		if (!task_detached(p)) {
1305
			do_notify_parent(p, p->exit_signal);
1306
			if (!task_detached(p)) {
1307 1308
				p->exit_state = EXIT_ZOMBIE;
				p = NULL;
L
Linus Torvalds 已提交
1309 1310 1311 1312 1313 1314
			}
		}
		write_unlock_irq(&tasklist_lock);
	}
	if (p != NULL)
		release_task(p);
1315

L
Linus Torvalds 已提交
1316 1317 1318
	return retval;
}

1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330
static int *task_stopped_code(struct task_struct *p, bool ptrace)
{
	if (ptrace) {
		if (task_is_stopped_or_traced(p))
			return &p->exit_code;
	} else {
		if (p->signal->flags & SIGNAL_STOP_STOPPED)
			return &p->signal->group_exit_code;
	}
	return NULL;
}

L
Linus Torvalds 已提交
1331 1332 1333 1334 1335 1336
/*
 * 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
1337
static int wait_task_stopped(int ptrace, struct task_struct *p,
R
Roland McGrath 已提交
1338
			     int options, struct siginfo __user *infop,
L
Linus Torvalds 已提交
1339 1340
			     int __user *stat_addr, struct rusage __user *ru)
{
1341
	int retval, exit_code, *p_code, why;
1342
	uid_t uid = 0; /* unneeded, required by compiler */
1343
	pid_t pid;
L
Linus Torvalds 已提交
1344

R
Roland McGrath 已提交
1345
	if (!(options & WUNTRACED))
R
Roland McGrath 已提交
1346 1347
		return 0;

1348 1349 1350
	exit_code = 0;
	spin_lock_irq(&p->sighand->siglock);

1351 1352
	p_code = task_stopped_code(p, ptrace);
	if (unlikely(!p_code))
1353 1354
		goto unlock_sig;

1355
	exit_code = *p_code;
1356 1357 1358
	if (!exit_code)
		goto unlock_sig;

R
Roland McGrath 已提交
1359
	if (!unlikely(options & WNOWAIT))
1360
		*p_code = 0;
1361

1362 1363
	/* don't need the RCU readlock here as we're holding a spinlock */
	uid = __task_cred(p)->uid;
1364 1365 1366
unlock_sig:
	spin_unlock_irq(&p->sighand->siglock);
	if (!exit_code)
L
Linus Torvalds 已提交
1367 1368 1369 1370 1371 1372 1373 1374 1375 1376
		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);
1377
	pid = task_pid_vnr(p);
R
Roland McGrath 已提交
1378
	why = ptrace ? CLD_TRAPPED : CLD_STOPPED;
L
Linus Torvalds 已提交
1379 1380
	read_unlock(&tasklist_lock);

R
Roland McGrath 已提交
1381
	if (unlikely(options & WNOWAIT))
L
Linus Torvalds 已提交
1382
		return wait_noreap_copyout(p, pid, uid,
1383
					   why, exit_code,
L
Linus Torvalds 已提交
1384 1385 1386 1387 1388 1389 1390 1391 1392 1393
					   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
1394
		retval = put_user((short)why, &infop->si_code);
L
Linus Torvalds 已提交
1395 1396 1397
	if (!retval && infop)
		retval = put_user(exit_code, &infop->si_status);
	if (!retval && infop)
1398
		retval = put_user(pid, &infop->si_pid);
L
Linus Torvalds 已提交
1399
	if (!retval && infop)
1400
		retval = put_user(uid, &infop->si_uid);
L
Linus Torvalds 已提交
1401
	if (!retval)
1402
		retval = pid;
L
Linus Torvalds 已提交
1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414
	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
1415
static int wait_task_continued(struct task_struct *p, int options,
L
Linus Torvalds 已提交
1416 1417 1418 1419 1420 1421 1422
			       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
1423 1424 1425
	if (!unlikely(options & WCONTINUED))
		return 0;

L
Linus Torvalds 已提交
1426 1427 1428 1429 1430 1431 1432 1433 1434
	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
1435
	if (!unlikely(options & WNOWAIT))
L
Linus Torvalds 已提交
1436
		p->signal->flags &= ~SIGNAL_STOP_CONTINUED;
1437
	uid = __task_cred(p)->uid;
L
Linus Torvalds 已提交
1438 1439
	spin_unlock_irq(&p->sighand->siglock);

1440
	pid = task_pid_vnr(p);
L
Linus Torvalds 已提交
1441 1442 1443 1444 1445 1446 1447 1448 1449
	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)
1450
			retval = pid;
L
Linus Torvalds 已提交
1451 1452 1453 1454 1455 1456 1457 1458 1459 1460
	} 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
1461 1462 1463 1464 1465 1466
/*
 * 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;
1467 1468
 * 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
1469
 */
R
Roland McGrath 已提交
1470
static int wait_consider_task(struct task_struct *parent, int ptrace,
R
Roland McGrath 已提交
1471 1472 1473 1474 1475 1476
			      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);
1477
	if (!ret)
R
Roland McGrath 已提交
1478 1479
		return ret;

1480 1481 1482 1483 1484 1485 1486 1487 1488 1489 1490 1491
	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
1492 1493 1494 1495 1496 1497 1498 1499 1500
	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
1501 1502 1503 1504 1505 1506 1507 1508 1509 1510 1511 1512 1513 1514 1515
	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;

1516
	if (task_stopped_code(p, ptrace))
R
Roland McGrath 已提交
1517 1518
		return wait_task_stopped(ptrace, p, options,
					 infop, stat_addr, ru);
R
Roland McGrath 已提交
1519 1520 1521 1522 1523 1524 1525 1526 1527 1528

	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
1529 1530
 * *@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
1531 1532 1533 1534 1535 1536 1537 1538 1539
 */
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
1540 1541 1542 1543 1544 1545 1546 1547 1548 1549
		/*
		 * 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
1550 1551 1552 1553 1554 1555 1556 1557 1558 1559 1560 1561 1562
	}

	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
1563
	 * Traditionally we see ptrace'd stopped tasks regardless of options.
R
Roland McGrath 已提交
1564
	 */
R
Roland McGrath 已提交
1565
	options |= WUNTRACED;
R
Roland McGrath 已提交
1566

R
Roland McGrath 已提交
1567 1568 1569 1570 1571
	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
1572 1573 1574 1575 1576 1577
			return ret;
	}

	return 0;
}

E
Eric W. Biederman 已提交
1578 1579 1580
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
1581 1582 1583
{
	DECLARE_WAITQUEUE(wait, current);
	struct task_struct *tsk;
R
Roland McGrath 已提交
1584
	int retval;
L
Linus Torvalds 已提交
1585

1586 1587
	trace_sched_process_wait(pid);

L
Linus Torvalds 已提交
1588 1589
	add_wait_queue(&current->signal->wait_chldexit,&wait);
repeat:
R
Roland McGrath 已提交
1590 1591 1592 1593 1594
	/*
	 * 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
1595 1596 1597 1598
	retval = -ECHILD;
	if ((type < PIDTYPE_MAX) && (!pid || hlist_empty(&pid->tasks[type])))
		goto end;

L
Linus Torvalds 已提交
1599 1600 1601 1602
	current->state = TASK_INTERRUPTIBLE;
	read_lock(&tasklist_lock);
	tsk = current;
	do {
R
Roland McGrath 已提交
1603 1604 1605 1606 1607 1608 1609 1610 1611 1612 1613 1614 1615
		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
1616
		}
R
Roland McGrath 已提交
1617

L
Linus Torvalds 已提交
1618 1619 1620
		if (options & __WNOTHREAD)
			break;
		tsk = next_thread(tsk);
E
Eric Sesterhenn 已提交
1621
		BUG_ON(tsk->signal != current->signal);
L
Linus Torvalds 已提交
1622 1623
	} while (tsk != current);
	read_unlock(&tasklist_lock);
O
Oleg Nesterov 已提交
1624

R
Roland McGrath 已提交
1625
	if (!retval && !(options & WNOHANG)) {
L
Linus Torvalds 已提交
1626
		retval = -ERESTARTSYS;
R
Roland McGrath 已提交
1627 1628 1629 1630
		if (!signal_pending(current)) {
			schedule();
			goto repeat;
		}
L
Linus Torvalds 已提交
1631
	}
R
Roland McGrath 已提交
1632

L
Linus Torvalds 已提交
1633 1634 1635 1636 1637
end:
	current->state = TASK_RUNNING;
	remove_wait_queue(&current->signal->wait_chldexit,&wait);
	if (infop) {
		if (retval > 0)
1638
			retval = 0;
L
Linus Torvalds 已提交
1639 1640 1641 1642 1643 1644 1645 1646 1647 1648 1649 1650 1651 1652 1653 1654 1655 1656 1657 1658 1659 1660 1661
		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;
}

1662 1663
SYSCALL_DEFINE5(waitid, int, which, pid_t, upid, struct siginfo __user *,
		infop, int, options, struct rusage __user *, ru)
L
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{
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	struct pid *pid = NULL;
	enum pid_type type;
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	long ret;

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

	switch (which) {
	case P_ALL:
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		type = PIDTYPE_MAX;
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		break;
	case P_PID:
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		type = PIDTYPE_PID;
		if (upid <= 0)
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			return -EINVAL;
		break;
	case P_PGID:
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		type = PIDTYPE_PGID;
		if (upid <= 0)
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			return -EINVAL;
		break;
	default:
		return -EINVAL;
	}

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	if (type < PIDTYPE_MAX)
		pid = find_get_pid(upid);
	ret = do_wait(type, pid, options, infop, NULL, ru);
	put_pid(pid);
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	/* avoid REGPARM breakage on x86: */
1698
	asmlinkage_protect(5, ret, which, upid, infop, options, ru);
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	return ret;
}

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SYSCALL_DEFINE4(wait4, pid_t, upid, int __user *, stat_addr,
		int, options, struct rusage __user *, ru)
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{
E
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	struct pid *pid = NULL;
	enum pid_type type;
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	long ret;

	if (options & ~(WNOHANG|WUNTRACED|WCONTINUED|
			__WNOTHREAD|__WCLONE|__WALL))
		return -EINVAL;
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	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;
1720
		pid = get_task_pid(current, PIDTYPE_PGID);
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	} 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);
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	/* avoid REGPARM breakage on x86: */
1730
	asmlinkage_protect(4, ret, upid, stat_addr, options, ru);
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	return ret;
}

#ifdef __ARCH_WANT_SYS_WAITPID

/*
 * sys_waitpid() remains for compatibility. waitpid() should be
 * implemented by calling sys_wait4() from libc.a.
 */
1740
SYSCALL_DEFINE3(waitpid, pid_t, pid, int __user *, stat_addr, int, options)
L
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{
	return sys_wait4(pid, stat_addr, options, NULL);
}

#endif