Commit message: TTY: drop driver reference in tty_open fail path

When tty_driver_lookup_tty fails in tty_open, we forget to drop a
reference to the tty driver. This was added by commit 4a2b5fddd5 (Move
tty lookup/reopen to caller).

Fix that by adding tty_driver_kref_put to the fail path.

I will refactor the code later. This is for the ease of backporting to
stable.

Introduced-in: v2.6.28-rc2
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: stable <stable@vger.kernel.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Acked-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
CVE: CVE-2011-5321
CWE: CWE-703
Vulnerability description: The tty_open function in drivers/tty/tty_io.c in the Linux kernel before 3.1.1 mishandles a driver-lookup failure, which allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact via crafted access to a device file under the /dev/pts directory.

Project: linux
File: tty_io.c

void __do_SAK(struct tty_struct *tty)
{
#ifdef TTY_SOFT_SAK
	tty_hangup(tty);
#else
	struct task_struct *g, *p;
	struct pid *session;
	int		i;
	struct file	*filp;
	struct fdtable *fdt;

	if (!tty)
		return;
	session = tty->session;

	tty_ldisc_flush(tty);

	tty_driver_flush_buffer(tty);

	read_lock(&tasklist_lock);
	/* Kill the entire session */
	do_each_pid_task(session, PIDTYPE_SID, p) {
		printk(KERN_NOTICE "SAK: killed process %d"
			" (%s): task_session(p)==tty->session\n",
			task_pid_nr(p), p->comm);
		send_sig(SIGKILL, p, 1);
	} while_each_pid_task(session, PIDTYPE_SID, p);
	/* Now kill any processes that happen to have the
	 * tty open.
	 */
	do_each_thread(g, p) {
		if (p->signal->tty == tty) {
			printk(KERN_NOTICE "SAK: killed process %d"
			    " (%s): task_session(p)==tty->session\n",
			    task_pid_nr(p), p->comm);
			send_sig(SIGKILL, p, 1);
			continue;
		}
		task_lock(p);
		if (p->files) {
			/*
			 * We don't take a ref to the file, so we must
			 * hold ->file_lock instead.
			 */
			spin_lock(&p->files->file_lock);
			fdt = files_fdtable(p->files);
			for (i = 0; i < fdt->max_fds; i++) {
				filp = fcheck_files(p->files, i);
				if (!filp)
					continue;
				if (filp->f_op->read == tty_read &&
				    file_tty(filp) == tty) {
					printk(KERN_NOTICE "SAK: killed process %d"
					    " (%s): fd#%d opened to the tty\n",
					    task_pid_nr(p), p->comm, i);
					force_sig(SIGKILL, p);
					break;
				}
			}
			spin_unlock(&p->files->file_lock);
		}
		task_unlock(p);
	} while_each_thread(g, p);
	read_unlock(&tasklist_lock);
#endif
}

Project: linux
File: tty_io.c

static int __tty_fasync(int fd, struct file *filp, int on)
{
	struct tty_struct *tty = file_tty(filp);
	unsigned long flags;
	int retval = 0;

	if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_fasync"))
		goto out;

	retval = fasync_helper(fd, filp, on, &tty->fasync);
	if (retval <= 0)
		goto out;

	if (on) {
		enum pid_type type;
		struct pid *pid;
		if (!waitqueue_active(&tty->read_wait))
			tty->minimum_to_wake = 1;
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		if (tty->pgrp) {
			pid = tty->pgrp;
			type = PIDTYPE_PGID;
		} else {
			pid = task_pid(current);
			type = PIDTYPE_PID;
		}
		get_pid(pid);
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		retval = __f_setown(filp, pid, type, 0);
		put_pid(pid);
		if (retval)
			goto out;
	} else {
		if (!tty->fasync && !waitqueue_active(&tty->read_wait))
			tty->minimum_to_wake = N_TTY_BUF_SIZE;
	}
	retval = 0;
out:
	return retval;
}

Project: linux
File: tty_io.c

void __tty_hangup(struct tty_struct *tty)
{
	struct file *cons_filp = NULL;
	struct file *filp, *f = NULL;
	struct task_struct *p;
	struct tty_file_private *priv;
	int    closecount = 0, n;
	unsigned long flags;
	int refs = 0;

	if (!tty)
		return;


	spin_lock(&redirect_lock);
	if (redirect && file_tty(redirect) == tty) {
		f = redirect;
		redirect = NULL;
	}
	spin_unlock(&redirect_lock);

	tty_lock();

	/* some functions below drop BTM, so we need this bit */
	set_bit(TTY_HUPPING, &tty->flags);

	/* inuse_filps is protected by the single tty lock,
	   this really needs to change if we want to flush the
	   workqueue with the lock held */
	check_tty_count(tty, "tty_hangup");

	spin_lock(&tty_files_lock);
	/* This breaks for file handles being sent over AF_UNIX sockets ? */
	list_for_each_entry(priv, &tty->tty_files, list) {
		filp = priv->file;
		if (filp->f_op->write == redirected_tty_write)
			cons_filp = filp;
		if (filp->f_op->write != tty_write)
			continue;
		closecount++;
		__tty_fasync(-1, filp, 0);	/* can't block */
		filp->f_op = &hung_up_tty_fops;
	}
	spin_unlock(&tty_files_lock);

	/*
	 * it drops BTM and thus races with reopen
	 * we protect the race by TTY_HUPPING
	 */
	tty_ldisc_hangup(tty);

	read_lock(&tasklist_lock);
	if (tty->session) {
		do_each_pid_task(tty->session, PIDTYPE_SID, p) {
			spin_lock_irq(&p->sighand->siglock);
			if (p->signal->tty == tty) {
				p->signal->tty = NULL;
				/* We defer the dereferences outside fo
				   the tasklist lock */
				refs++;
			}
			if (!p->signal->leader) {
				spin_unlock_irq(&p->sighand->siglock);
				continue;
			}
			__group_send_sig_info(SIGHUP, SEND_SIG_PRIV, p);
			__group_send_sig_info(SIGCONT, SEND_SIG_PRIV, p);
			put_pid(p->signal->tty_old_pgrp);  /* A noop */
			spin_lock_irqsave(&tty->ctrl_lock, flags);
			if (tty->pgrp)
				p->signal->tty_old_pgrp = get_pid(tty->pgrp);
			spin_unlock_irqrestore(&tty->ctrl_lock, flags);
			spin_unlock_irq(&p->sighand->siglock);
		} while_each_pid_task(tty->session, PIDTYPE_SID, p);
	}
	read_unlock(&tasklist_lock);

	spin_lock_irqsave(&tty->ctrl_lock, flags);
	clear_bit(TTY_THROTTLED, &tty->flags);
	clear_bit(TTY_PUSH, &tty->flags);
	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
	put_pid(tty->session);
	put_pid(tty->pgrp);
	tty->session = NULL;
	tty->pgrp = NULL;
	tty->ctrl_status = 0;
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);

	/* Account for the p->signal references we killed */
	while (refs--)
		tty_kref_put(tty);

	/*
	 * If one of the devices matches a console pointer, we
	 * cannot just call hangup() because that will cause
	 * tty->count and state->count to go out of sync.
	 * So we just call close() the right number of times.
	 */
	if (cons_filp) {
		if (tty->ops->close)
			for (n = 0; n < closecount; n++)
				tty->ops->close(tty, cons_filp);
	} else if (tty->ops->hangup)
		(tty->ops->hangup)(tty);
	/*
	 * We don't want to have driver/ldisc interactions beyond
	 * the ones we did here. The driver layer expects no
	 * calls after ->hangup() from the ldisc side. However we
	 * can't yet guarantee all that.
	 */
	set_bit(TTY_HUPPED, &tty->flags);
	clear_bit(TTY_HUPPING, &tty->flags);
	tty_ldisc_enable(tty);

	tty_unlock();

	if (f)
		fput(f);
}

Project: linux
File: tty_io.c

struct tty_driver *alloc_tty_driver(int lines)
{
	struct tty_driver *driver;

	driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
	if (driver) {
		kref_init(&driver->kref);
		driver->magic = TTY_DRIVER_MAGIC;
		driver->num = lines;
		/* later we'll move allocation of tables here */
	}
	return driver;
}

Project: linux
File: tty_io.c

struct tty_struct *alloc_tty_struct(void)
{
	return kzalloc(sizeof(struct tty_struct), GFP_KERNEL);
}

Project: linux
File: tty_io.c

static int check_tty_count(struct tty_struct *tty, const char *routine)
{
#ifdef CHECK_TTY_COUNT
	struct list_head *p;
	int count = 0;

	spin_lock(&tty_files_lock);
	list_for_each(p, &tty->tty_files) {
		count++;
	}
	spin_unlock(&tty_files_lock);
	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
	    tty->driver->subtype == PTY_TYPE_SLAVE &&
	    tty->link && tty->link->count)
		count++;
	if (tty->count != count) {
		printk(KERN_WARNING "Warning: dev (%s) tty->count(%d) "
				    "!= #fd's(%d) in %s\n",
		       tty->name, tty->count, count, routine);
		return count;
	}
#endif
	return 0;
}

Project: linux
File: tty_io.c

static void destruct_tty_driver(struct kref *kref)
{
	struct tty_driver *driver = container_of(kref, struct tty_driver, kref);
	int i;
	struct ktermios *tp;
	void *p;

	if (driver->flags & TTY_DRIVER_INSTALLED) {
		/*
		 * Free the termios and termios_locked structures because
		 * we don't want to get memory leaks when modular tty
		 * drivers are removed from the kernel.
		 */
		for (i = 0; i < driver->num; i++) {
			tp = driver->termios[i];
			if (tp) {
				driver->termios[i] = NULL;
				kfree(tp);
			}
			if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV))
				tty_unregister_device(driver, i);
		}
		p = driver->ttys;
		proc_tty_unregister_driver(driver);
		driver->ttys = NULL;
		driver->termios = NULL;
		kfree(p);
		cdev_del(&driver->cdev);
	}
	kfree(driver);
}

Project: linux
File: tty_io.c

static int dev_match_devt(struct device *dev, void *data)
{
	dev_t *devt = data;
	return dev->devt == *devt;
}

Project: linux
File: tty_io.c

void disassociate_ctty(int on_exit)
{
	struct tty_struct *tty;
	struct pid *tty_pgrp = NULL;

	if (!current->signal->leader)
		return;

	tty = get_current_tty();
	if (tty) {
		tty_pgrp = get_pid(tty->pgrp);
		if (on_exit) {
			if (tty->driver->type != TTY_DRIVER_TYPE_PTY)
				tty_vhangup(tty);
		}
		tty_kref_put(tty);
	} else if (on_exit) {
		struct pid *old_pgrp;
		spin_lock_irq(&current->sighand->siglock);
		old_pgrp = current->signal->tty_old_pgrp;
		current->signal->tty_old_pgrp = NULL;
		spin_unlock_irq(&current->sighand->siglock);
		if (old_pgrp) {
			kill_pgrp(old_pgrp, SIGHUP, on_exit);
			kill_pgrp(old_pgrp, SIGCONT, on_exit);
			put_pid(old_pgrp);
		}
		return;
	}
	if (tty_pgrp) {
		kill_pgrp(tty_pgrp, SIGHUP, on_exit);
		if (!on_exit)
			kill_pgrp(tty_pgrp, SIGCONT, on_exit);
		put_pid(tty_pgrp);
	}

	spin_lock_irq(&current->sighand->siglock);
	put_pid(current->signal->tty_old_pgrp);
	current->signal->tty_old_pgrp = NULL;
	spin_unlock_irq(&current->sighand->siglock);

	tty = get_current_tty();
	if (tty) {
		unsigned long flags;
		spin_lock_irqsave(&tty->ctrl_lock, flags);
		put_pid(tty->session);
		put_pid(tty->pgrp);
		tty->session = NULL;
		tty->pgrp = NULL;
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		tty_kref_put(tty);
	} else {
#ifdef TTY_DEBUG_HANGUP
		printk(KERN_DEBUG "error attempted to write to tty [0x%p]"
		       " = NULL", tty);
#endif
	}

	/* Now clear signal->tty under the lock */
	read_lock(&tasklist_lock);
	session_clear_tty(task_session(current));
	read_unlock(&tasklist_lock);
}

Project: linux
File: tty_io.c

static void do_tty_hangup(struct work_struct *work)
{
	struct tty_struct *tty =
		container_of(work, struct tty_struct, hangup_work);

	__tty_hangup(tty);
}

Project: linux
File: tty_io.c

static inline ssize_t do_tty_write(
	ssize_t (*write)(struct tty_struct *, struct file *, const unsigned char *, size_t),
	struct tty_struct *tty,
	struct file *file,
	const char __user *buf,
	size_t count)
{
	ssize_t ret, written = 0;
	unsigned int chunk;

	ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
	if (ret < 0)
		return ret;

	/*
	 * We chunk up writes into a temporary buffer. This
	 * simplifies low-level drivers immensely, since they
	 * don't have locking issues and user mode accesses.
	 *
	 * But if TTY_NO_WRITE_SPLIT is set, we should use a
	 * big chunk-size..
	 *
	 * The default chunk-size is 2kB, because the NTTY
	 * layer has problems with bigger chunks. It will
	 * claim to be able to handle more characters than
	 * it actually does.
	 *
	 * FIXME: This can probably go away now except that 64K chunks
	 * are too likely to fail unless switched to vmalloc...
	 */
	chunk = 2048;
	if (test_bit(TTY_NO_WRITE_SPLIT, &tty->flags))
		chunk = 65536;
	if (count < chunk)
		chunk = count;

	/* write_buf/write_cnt is protected by the atomic_write_lock mutex */
	if (tty->write_cnt < chunk) {
		unsigned char *buf_chunk;

		if (chunk < 1024)
			chunk = 1024;

		buf_chunk = kmalloc(chunk, GFP_KERNEL);
		if (!buf_chunk) {
			ret = -ENOMEM;
			goto out;
		}
		kfree(tty->write_buf);
		tty->write_cnt = chunk;
		tty->write_buf = buf_chunk;
	}

	/* Do the write .. */
	for (;;) {
		size_t size = count;
		if (size > chunk)
			size = chunk;
		ret = -EFAULT;
		if (copy_from_user(tty->write_buf, buf, size))
			break;
		ret = write(tty, file, tty->write_buf, size);
		if (ret <= 0)
			break;
		written += ret;
		buf += ret;
		count -= ret;
		if (!count)
			break;
		ret = -ERESTARTSYS;
		if (signal_pending(current))
			break;
		cond_resched();
	}
	if (written) {
		struct inode *inode = file->f_path.dentry->d_inode;
		inode->i_mtime = current_fs_time(inode->i_sb);
		ret = written;
	}
out:
	tty_write_unlock(tty);
	return ret;
}

Project: linux
File: tty_io.c

void free_tty_struct(struct tty_struct *tty)
{
	if (tty->dev)
		put_device(tty->dev);
	kfree(tty->write_buf);
	tty_buffer_free_all(tty);
	kfree(tty);
}

Project: linux
File: tty_io.c

void initialize_tty_struct(struct tty_struct *tty,
		struct tty_driver *driver, int idx)
{
	memset(tty, 0, sizeof(struct tty_struct));
	kref_init(&tty->kref);
	tty->magic = TTY_MAGIC;
	tty_ldisc_init(tty);
	tty->session = NULL;
	tty->pgrp = NULL;
	tty->overrun_time = jiffies;
	tty->buf.head = tty->buf.tail = NULL;
	tty_buffer_init(tty);
	mutex_init(&tty->termios_mutex);
	mutex_init(&tty->ldisc_mutex);
	init_waitqueue_head(&tty->write_wait);
	init_waitqueue_head(&tty->read_wait);
	INIT_WORK(&tty->hangup_work, do_tty_hangup);
	mutex_init(&tty->atomic_read_lock);
	mutex_init(&tty->atomic_write_lock);
	mutex_init(&tty->output_lock);
	mutex_init(&tty->echo_lock);
	spin_lock_init(&tty->read_lock);
	spin_lock_init(&tty->ctrl_lock);
	INIT_LIST_HEAD(&tty->tty_files);
	INIT_WORK(&tty->SAK_work, do_SAK_work);

	tty->driver = driver;
	tty->ops = driver->ops;
	tty->index = idx;
	tty_line_name(driver, idx, tty->name);
	tty->dev = tty_get_device(tty);
}

Project: linux
File: tty_io.c

void no_tty(void)
{
	struct task_struct *tsk = current;
	tty_lock();
	disassociate_ctty(0);
	tty_unlock();
	proc_clear_tty(tsk);
}

Project: linux
File: tty_io.c

static void proc_set_tty(struct task_struct *tsk, struct tty_struct *tty)
{
	spin_lock_irq(&tsk->sighand->siglock);
	__proc_set_tty(tsk, tty);
	spin_unlock_irq(&tsk->sighand->siglock);
}

Project: linux
File: tty_io.c

ssize_t redirected_tty_write(struct file *file, const char __user *buf,
						size_t count, loff_t *ppos)
{
	struct file *p = NULL;

	spin_lock(&redirect_lock);
	if (redirect) {
		get_file(redirect);
		p = redirect;
	}
	spin_unlock(&redirect_lock);

	if (p) {
		ssize_t res;
		res = vfs_write(p, buf, count, &p->f_pos);
		fput(p);
		return res;
	}
	return tty_write(file, buf, count, ppos);
}

Project: linux
File: tty_io.c

static void release_one_tty(struct work_struct *work)
{
	struct tty_struct *tty =
		container_of(work, struct tty_struct, hangup_work);
	struct tty_driver *driver = tty->driver;

	if (tty->ops->cleanup)
		tty->ops->cleanup(tty);

	tty->magic = 0;
	tty_driver_kref_put(driver);
	module_put(driver->owner);

	spin_lock(&tty_files_lock);
	list_del_init(&tty->tty_files);
	spin_unlock(&tty_files_lock);

	put_pid(tty->pgrp);
	put_pid(tty->session);
	free_tty_struct(tty);
}

Project: linux
File: tty_io.c

static void release_tty(struct tty_struct *tty, int idx)
{
	/* This should always be true but check for the moment */
	WARN_ON(tty->index != idx);

	if (tty->link)
		tty_kref_put(tty->link);
	tty_kref_put(tty);
}

Project: linux
File: tty_io.c

static ssize_t show_cons_active(struct device *dev,
				struct device_attribute *attr, char *buf)
{
	struct console *cs[16];
	int i = 0;
	struct console *c;
	ssize_t count = 0;

	console_lock();
	for_each_console(c) {
		if (!c->device)
			continue;
		if (!c->write)
			continue;
		if ((c->flags & CON_ENABLED) == 0)
			continue;
		cs[i++] = c;
		if (i >= ARRAY_SIZE(cs))
			break;
	}
	while (i--)
		count += sprintf(buf + count, "%s%d%c",
				 cs[i]->name, cs[i]->index, i ? ' ':'\n');
	console_unlock();

	return count;
}

Project: linux
File: tty_io.c

void start_tty(struct tty_struct *tty)
{
	unsigned long flags;
	spin_lock_irqsave(&tty->ctrl_lock, flags);
	if (!tty->stopped || tty->flow_stopped) {
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		return;
	}
	tty->stopped = 0;
	if (tty->link && tty->link->packet) {
		tty->ctrl_status &= ~TIOCPKT_STOP;
		tty->ctrl_status |= TIOCPKT_START;
		wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
	}
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
	if (tty->ops->start)
		(tty->ops->start)(tty);
	/* If we have a running line discipline it may need kicking */
	tty_wakeup(tty);
}

Project: linux
File: tty_io.c

void stop_tty(struct tty_struct *tty)
{
	unsigned long flags;
	spin_lock_irqsave(&tty->ctrl_lock, flags);
	if (tty->stopped) {
		spin_unlock_irqrestore(&tty->ctrl_lock, flags);
		return;
	}
	tty->stopped = 1;
	if (tty->link && tty->link->packet) {
		tty->ctrl_status &= ~TIOCPKT_START;
		tty->ctrl_status |= TIOCPKT_STOP;
		wake_up_interruptible_poll(&tty->link->read_wait, POLLIN);
	}
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
	if (tty->ops->stop)
		(tty->ops->stop)(tty);
}

Project: linux
File: tty_io.c

static int tioccons(struct file *file)
{
	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;
	if (file->f_op->write == redirected_tty_write) {
		struct file *f;
		spin_lock(&redirect_lock);
		f = redirect;
		redirect = NULL;
		spin_unlock(&redirect_lock);
		if (f)
			fput(f);
		return 0;
	}
	spin_lock(&redirect_lock);
	if (redirect) {
		spin_unlock(&redirect_lock);
		return -EBUSY;
	}
	get_file(file);
	redirect = file;
	spin_unlock(&redirect_lock);
	return 0;
}

Project: linux
File: tty_io.c

static int tiocgwinsz(struct tty_struct *tty, struct winsize __user *arg)
{
	int err;

	mutex_lock(&tty->termios_mutex);
	err = copy_to_user(arg, &tty->winsize, sizeof(*arg));
	mutex_unlock(&tty->termios_mutex);

	return err ? -EFAULT: 0;
}

Project: linux
File: tty_io.c

static int tiocsctty(struct tty_struct *tty, int arg)
{
	int ret = 0;
	if (current->signal->leader && (task_session(current) == tty->session))
		return ret;

	mutex_lock(&tty_mutex);
	/*
	 * The process must be a session leader and
	 * not have a controlling tty already.
	 */
	if (!current->signal->leader || current->signal->tty) {
		ret = -EPERM;
		goto unlock;
	}

	if (tty->session) {
		/*
		 * This tty is already the controlling
		 * tty for another session group!
		 */
		if (arg == 1 && capable(CAP_SYS_ADMIN)) {
			/*
			 * Steal it away
			 */
			read_lock(&tasklist_lock);
			session_clear_tty(tty->session);
			read_unlock(&tasklist_lock);
		} else {
			ret = -EPERM;
			goto unlock;
		}
	}
	proc_set_tty(current, tty);
unlock:
	mutex_unlock(&tty_mutex);
	return ret;
}

Project: linux
File: tty_io.c

int tty_add_file(struct tty_struct *tty, struct file *file)
{
	struct tty_file_private *priv;

	priv = kmalloc(sizeof(*priv), GFP_KERNEL);
	if (!priv)
		return -ENOMEM;

	priv->tty = tty;
	priv->file = file;
	file->private_data = priv;

	spin_lock(&tty_files_lock);
	list_add(&priv->list, &tty->tty_files);
	spin_unlock(&tty_files_lock);

	return 0;
}

Project: linux
File: tty_io.c

int tty_check_change(struct tty_struct *tty)
{
	unsigned long flags;
	int ret = 0;

	if (current->signal->tty != tty)
		return 0;

	spin_lock_irqsave(&tty->ctrl_lock, flags);

	if (!tty->pgrp) {
		printk(KERN_WARNING "tty_check_change: tty->pgrp == NULL!\n");
		goto out_unlock;
	}
	if (task_pgrp(current) == tty->pgrp)
		goto out_unlock;
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
	if (is_ignored(SIGTTOU))
		goto out;
	if (is_current_pgrp_orphaned()) {
		ret = -EIO;
		goto out;
	}
	kill_pgrp(task_pgrp(current), SIGTTOU, 1);
	set_thread_flag(TIF_SIGPENDING);
	ret = -ERESTARTSYS;
out:
	return ret;
out_unlock:
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);
	return ret;
}

Project: linux
File: tty_io.c

static long tty_compat_ioctl(struct file *file, unsigned int cmd,
				unsigned long arg)
{
	struct inode *inode = file->f_dentry->d_inode;
	struct tty_struct *tty = file_tty(file);
	struct tty_ldisc *ld;
	int retval = -ENOIOCTLCMD;

	if (tty_paranoia_check(tty, inode, "tty_ioctl"))
		return -EINVAL;

	if (tty->ops->compat_ioctl) {
		retval = (tty->ops->compat_ioctl)(tty, cmd, arg);
		if (retval != -ENOIOCTLCMD)
			return retval;
	}

	ld = tty_ldisc_ref_wait(tty);
	if (ld->ops->compat_ioctl)
		retval = ld->ops->compat_ioctl(tty, file, cmd, arg);
	else
		retval = n_tty_compat_ioctl_helper(tty, file, cmd, arg);
	tty_ldisc_deref(ld);

	return retval;
}

Project: linux
File: tty_io.c

void tty_del_file(struct file *file)
{
	struct tty_file_private *priv = file->private_data;

	spin_lock(&tty_files_lock);
	list_del(&priv->list);
	spin_unlock(&tty_files_lock);
	file->private_data = NULL;
	kfree(priv);
}

Project: linux
File: tty_io.c

static char *tty_devnode(struct device *dev, mode_t *mode)
{
	if (!mode)
		return NULL;
	if (dev->devt == MKDEV(TTYAUX_MAJOR, 0) ||
	    dev->devt == MKDEV(TTYAUX_MAJOR, 2))
		*mode = 0666;
	return NULL;
}

Project: linux
File: tty_io.c

int tty_do_resize(struct tty_struct *tty, struct winsize *ws)
{
	struct pid *pgrp;
	unsigned long flags;

	/* Lock the tty */
	mutex_lock(&tty->termios_mutex);
	if (!memcmp(ws, &tty->winsize, sizeof(*ws)))
		goto done;
	/* Get the PID values and reference them so we can
	   avoid holding the tty ctrl lock while sending signals */
	spin_lock_irqsave(&tty->ctrl_lock, flags);
	pgrp = get_pid(tty->pgrp);
	spin_unlock_irqrestore(&tty->ctrl_lock, flags);

	if (pgrp)
		kill_pgrp(pgrp, SIGWINCH, 1);
	put_pid(pgrp);

	tty->winsize = *ws;
done:
	mutex_unlock(&tty->termios_mutex);
	return 0;
}

Project: linux
File: tty_io.c

static int tty_driver_install_tty(struct tty_driver *driver,
						struct tty_struct *tty)
{
	int idx = tty->index;
	int ret;

	if (driver->ops->install) {
		ret = driver->ops->install(driver, tty);
		return ret;
	}

	if (tty_init_termios(tty) == 0) {
		tty_driver_kref_get(driver);
		tty->count++;
		driver->ttys[idx] = tty;
		return 0;
	}
	return -ENOMEM;
}

Project: linux
File: tty_io.c

static struct tty_struct *tty_driver_lookup_tty(struct tty_driver *driver,
		struct inode *inode, int idx)
{
	struct tty_struct *tty;

	if (driver->ops->lookup)
		return driver->ops->lookup(driver, inode, idx);

	tty = driver->ttys[idx];
	return tty;
}

Project: linux
File: tty_io.c

static void tty_driver_remove_tty(struct tty_driver *driver,
						struct tty_struct *tty)
{
	if (driver->ops->remove)
		driver->ops->remove(driver, tty);
	else
		driver->ttys[tty->index] = NULL;
}

Project: linux
File: tty_io.c

static int tty_fasync(int fd, struct file *filp, int on)
{
	int retval;
	tty_lock();
	retval = __tty_fasync(fd, filp, on);
	tty_unlock();
	return retval;
}

Project: linux
File: tty_io.c

void tty_free_termios(struct tty_struct *tty)
{
	struct ktermios *tp;
	int idx = tty->index;
	/* Kill this flag and push into drivers for locking etc */
	if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
		/* FIXME: Locking on ->termios array */
		tp = tty->termios;
		tty->driver->termios[idx] = NULL;
		kfree(tp);
	}
}

Project: linux
File: tty_io.c

void tty_hangup(struct tty_struct *tty)
{
#ifdef TTY_DEBUG_HANGUP
	char	buf[64];
	printk(KERN_DEBUG "%s hangup...\n", tty_name(tty, buf));
#endif
	schedule_work(&tty->hangup_work);
}

Project: linux
File: tty_io.c

int __init tty_init(void)
{
	cdev_init(&tty_cdev, &tty_fops);
	if (cdev_add(&tty_cdev, MKDEV(TTYAUX_MAJOR, 0), 1) ||
	    register_chrdev_region(MKDEV(TTYAUX_MAJOR, 0), 1, "/dev/tty") < 0)
		panic("Couldn't register /dev/tty driver\n");
	device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 0), NULL, "tty");

	cdev_init(&console_cdev, &console_fops);
	if (cdev_add(&console_cdev, MKDEV(TTYAUX_MAJOR, 1), 1) ||
	    register_chrdev_region(MKDEV(TTYAUX_MAJOR, 1), 1, "/dev/console") < 0)
		panic("Couldn't register /dev/console driver\n");
	consdev = device_create(tty_class, NULL, MKDEV(TTYAUX_MAJOR, 1), NULL,
			      "console");
	if (IS_ERR(consdev))
		consdev = NULL;
	else
		WARN_ON(device_create_file(consdev, &dev_attr_active) < 0);

#ifdef CONFIG_VT
	vty_init(&console_fops);
#endif
	return 0;
}

Project: linux
File: tty_io.c

struct tty_struct *tty_init_dev(struct tty_driver *driver, int idx,
								int first_ok)
{
	struct tty_struct *tty;
	int retval;

	/* Check if pty master is being opened multiple times */
	if (driver->subtype == PTY_TYPE_MASTER &&
		(driver->flags & TTY_DRIVER_DEVPTS_MEM) && !first_ok) {
		return ERR_PTR(-EIO);
	}

	/*
	 * First time open is complex, especially for PTY devices.
	 * This code guarantees that either everything succeeds and the
	 * TTY is ready for operation, or else the table slots are vacated
	 * and the allocated memory released.  (Except that the termios
	 * and locked termios may be retained.)
	 */

	if (!try_module_get(driver->owner))
		return ERR_PTR(-ENODEV);

	tty = alloc_tty_struct();
	if (!tty) {
		retval = -ENOMEM;
		goto err_module_put;
	}
	initialize_tty_struct(tty, driver, idx);

	retval = tty_driver_install_tty(driver, tty);
	if (retval < 0)
		goto err_deinit_tty;

	/*
	 * Structures all installed ... call the ldisc open routines.
	 * If we fail here just call release_tty to clean up.  No need
	 * to decrement the use counts, as release_tty doesn't care.
	 */
	retval = tty_ldisc_setup(tty, tty->link);
	if (retval)
		goto err_release_tty;
	return tty;

err_deinit_tty:
	deinitialize_tty_struct(tty);
	free_tty_struct(tty);
err_module_put:
	module_put(driver->owner);
	return ERR_PTR(retval);

	/* call the tty release_tty routine to clean out this slot */
err_release_tty:
	printk_ratelimited(KERN_INFO "tty_init_dev: ldisc open failed, "
				 "clearing slot %d\n", idx);
	release_tty(tty, idx);
	return ERR_PTR(retval);
}

Project: linux
File: tty_io.c

int tty_init_termios(struct tty_struct *tty)
{
	struct ktermios *tp;
	int idx = tty->index;

	tp = tty->driver->termios[idx];
	if (tp == NULL) {
		tp = kzalloc(sizeof(struct ktermios[2]), GFP_KERNEL);
		if (tp == NULL)
			return -ENOMEM;
		memcpy(tp, &tty->driver->init_termios,
						sizeof(struct ktermios));
		tty->driver->termios[idx] = tp;
	}
	tty->termios = tp;
	tty->termios_locked = tp + 1;

	/* Compatibility until drivers always set this */
	tty->termios->c_ispeed = tty_termios_input_baud_rate(tty->termios);
	tty->termios->c_ospeed = tty_termios_baud_rate(tty->termios);
	return 0;
}

Project: linux
File: tty_io.c

long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
	struct tty_struct *tty = file_tty(file);
	struct tty_struct *real_tty;
	void __user *p = (void __user *)arg;
	int retval;
	struct tty_ldisc *ld;
	struct inode *inode = file->f_dentry->d_inode;

	if (tty_paranoia_check(tty, inode, "tty_ioctl"))
		return -EINVAL;

	real_tty = tty_pair_get_tty(tty);

	/*
	 * Factor out some common prep work
	 */
	switch (cmd) {
	case TIOCSETD:
	case TIOCSBRK:
	case TIOCCBRK:
	case TCSBRK:
	case TCSBRKP:
		retval = tty_check_change(tty);
		if (retval)
			return retval;
		if (cmd != TIOCCBRK) {
			tty_wait_until_sent(tty, 0);
			if (signal_pending(current))
				return -EINTR;
		}
		break;
	}

	/*
	 *	Now do the stuff.
	 */
	switch (cmd) {
	case TIOCSTI:
		return tiocsti(tty, p);
	case TIOCGWINSZ:
		return tiocgwinsz(real_tty, p);
	case TIOCSWINSZ:
		return tiocswinsz(real_tty, p);
	case TIOCCONS:
		return real_tty != tty ? -EINVAL : tioccons(file);
	case FIONBIO:
		return fionbio(file, p);
	case TIOCEXCL:
		set_bit(TTY_EXCLUSIVE, &tty->flags);
		return 0;
	case TIOCNXCL:
		clear_bit(TTY_EXCLUSIVE, &tty->flags);
		return 0;
	case TIOCNOTTY:
		if (current->signal->tty != tty)
			return -ENOTTY;
		no_tty();
		return 0;
	case TIOCSCTTY:
		return tiocsctty(tty, arg);
	case TIOCGPGRP:
		return tiocgpgrp(tty, real_tty, p);
	case TIOCSPGRP:
		return tiocspgrp(tty, real_tty, p);
	case TIOCGSID:
		return tiocgsid(tty, real_tty, p);
	case TIOCGETD:
		return put_user(tty->ldisc->ops->num, (int __user *)p);
	case TIOCSETD:
		return tiocsetd(tty, p);
	case TIOCVHANGUP:
		if (!capable(CAP_SYS_ADMIN))
			return -EPERM;
		tty_vhangup(tty);
		return 0;
	case TIOCGDEV:
	{
		unsigned int ret = new_encode_dev(tty_devnum(real_tty));
		return put_user(ret, (unsigned int __user *)p);
	}
	/*
	 * Break handling
	 */
	case TIOCSBRK:	/* Turn break on, unconditionally */
		if (tty->ops->break_ctl)
			return tty->ops->break_ctl(tty, -1);
		return 0;
	case TIOCCBRK:	/* Turn break off, unconditionally */
		if (tty->ops->break_ctl)
			return tty->ops->break_ctl(tty, 0);
		return 0;
	case TCSBRK:   /* SVID version: non-zero arg --> no break */
		/* non-zero arg means wait for all output data
		 * to be sent (performed above) but don't send break.
		 * This is used by the tcdrain() termios function.
		 */
		if (!arg)
			return send_break(tty, 250);
		return 0;
	case TCSBRKP:	/* support for POSIX tcsendbreak() */
		return send_break(tty, arg ? arg*100 : 250);

	case TIOCMGET:
		return tty_tiocmget(tty, p);
	case TIOCMSET:
	case TIOCMBIC:
	case TIOCMBIS:
		return tty_tiocmset(tty, cmd, p);
	case TIOCGICOUNT:
		retval = tty_tiocgicount(tty, p);
		/* For the moment allow fall through to the old method */
        	if (retval != -EINVAL)
			return retval;
		break;
	case TCFLSH:
		switch (arg) {
		case TCIFLUSH:
		case TCIOFLUSH:
		/* flush tty buffer and allow ldisc to process ioctl */
			tty_buffer_flush(tty);
			break;
		}
		break;
	}
	if (tty->ops->ioctl) {
		retval = (tty->ops->ioctl)(tty, cmd, arg);
		if (retval != -ENOIOCTLCMD)
			return retval;
	}
	ld = tty_ldisc_ref_wait(tty);
	retval = -EINVAL;
	if (ld->ops->ioctl) {
		retval = ld->ops->ioctl(tty, file, cmd, arg);
		if (retval == -ENOIOCTLCMD)
			retval = -EINVAL;
	}
	tty_ldisc_deref(ld);
	return retval;
}

Project: linux
File: tty_io.c

char *tty_name(struct tty_struct *tty, char *buf)
{
	if (!tty) /* Hmm.  NULL pointer.  That's fun. */
		strcpy(buf, "NULL tty");
	else
		strcpy(buf, tty->name);
	return buf;
}

Project: linux
File: tty_io.c

struct tty_struct *tty_pair_get_pty(struct tty_struct *tty)
{
	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
	    tty->driver->subtype == PTY_TYPE_MASTER)
	    return tty;
	return tty->link;
}

Project: linux
File: tty_io.c

struct tty_struct *tty_pair_get_tty(struct tty_struct *tty)
{
	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
	    tty->driver->subtype == PTY_TYPE_MASTER)
		tty = tty->link;
	return tty;
}

Project: linux
File: tty_io.c

int tty_paranoia_check(struct tty_struct *tty, struct inode *inode,
			      const char *routine)
{
#ifdef TTY_PARANOIA_CHECK
	if (!tty) {
		printk(KERN_WARNING
			"null TTY for (%d:%d) in %s\n",
			imajor(inode), iminor(inode), routine);
		return 1;
	}
	if (tty->magic != TTY_MAGIC) {
		printk(KERN_WARNING
			"bad magic number for tty struct (%d:%d) in %s\n",
			imajor(inode), iminor(inode), routine);
		return 1;
	}
#endif
	return 0;
}

Project: linux
File: tty_io.c

static unsigned int tty_poll(struct file *filp, poll_table *wait)
{
	struct tty_struct *tty = file_tty(filp);
	struct tty_ldisc *ld;
	int ret = 0;

	if (tty_paranoia_check(tty, filp->f_path.dentry->d_inode, "tty_poll"))
		return 0;

	ld = tty_ldisc_ref_wait(tty);
	if (ld->ops->poll)
		ret = (ld->ops->poll)(tty, filp, wait);
	tty_ldisc_deref(ld);
	return ret;
}

Project: linux
File: tty_io.c

static ssize_t tty_read(struct file *file, char __user *buf, size_t count,
			loff_t *ppos)
{
	int i;
	struct inode *inode = file->f_path.dentry->d_inode;
	struct tty_struct *tty = file_tty(file);
	struct tty_ldisc *ld;

	if (tty_paranoia_check(tty, inode, "tty_read"))
		return -EIO;
	if (!tty || (test_bit(TTY_IO_ERROR, &tty->flags)))
		return -EIO;

	/* We want to wait for the line discipline to sort out in this
	   situation */
	ld = tty_ldisc_ref_wait(tty);
	if (ld->ops->read)
		i = (ld->ops->read)(tty, file, buf, count);
	else
		i = -EIO;
	tty_ldisc_deref(ld);
	if (i > 0)
		inode->i_atime = current_fs_time(inode->i_sb);
	return i;
}

Project: linux
File: tty_io.c

struct device *tty_register_device(struct tty_driver *driver, unsigned index,
				   struct device *device)
{
	char name[64];
	dev_t dev = MKDEV(driver->major, driver->minor_start) + index;

	if (index >= driver->num) {
		printk(KERN_ERR "Attempt to register invalid tty line number "
		       " (%d).\n", index);
		return ERR_PTR(-EINVAL);
	}

	if (driver->type == TTY_DRIVER_TYPE_PTY)
		pty_line_name(driver, index, name);
	else
		tty_line_name(driver, index, name);

	return device_create(tty_class, device, dev, NULL, name);
}

Project: linux
File: tty_io.c

int tty_register_driver(struct tty_driver *driver)
{
	int error;
	int i;
	dev_t dev;
	void **p = NULL;
	struct device *d;

	if (!(driver->flags & TTY_DRIVER_DEVPTS_MEM) && driver->num) {
		p = kzalloc(driver->num * 2 * sizeof(void *), GFP_KERNEL);
		if (!p)
			return -ENOMEM;
	}

	if (!driver->major) {
		error = alloc_chrdev_region(&dev, driver->minor_start,
						driver->num, driver->name);
		if (!error) {
			driver->major = MAJOR(dev);
			driver->minor_start = MINOR(dev);
		}
	} else {
		dev = MKDEV(driver->major, driver->minor_start);
		error = register_chrdev_region(dev, driver->num, driver->name);
	}
	if (error < 0) {
		kfree(p);
		return error;
	}

	if (p) {
		driver->ttys = (struct tty_struct **)p;
		driver->termios = (struct ktermios **)(p + driver->num);
	} else {
		driver->ttys = NULL;
		driver->termios = NULL;
	}

	cdev_init(&driver->cdev, &tty_fops);
	driver->cdev.owner = driver->owner;
	error = cdev_add(&driver->cdev, dev, driver->num);
	if (error) {
		unregister_chrdev_region(dev, driver->num);
		driver->ttys = NULL;
		driver->termios = NULL;
		kfree(p);
		return error;
	}

	mutex_lock(&tty_mutex);
	list_add(&driver->tty_drivers, &tty_drivers);
	mutex_unlock(&tty_mutex);

	if (!(driver->flags & TTY_DRIVER_DYNAMIC_DEV)) {
		for (i = 0; i < driver->num; i++) {
			d = tty_register_device(driver, i, NULL);
			if (IS_ERR(d)) {
				error = PTR_ERR(d);
				goto err;
			}
		}
	}
	proc_tty_register_driver(driver);
	driver->flags |= TTY_DRIVER_INSTALLED;
	return 0;

err:
	for (i--; i >= 0; i--)
		tty_unregister_device(driver, i);

	mutex_lock(&tty_mutex);
	list_del(&driver->tty_drivers);
	mutex_unlock(&tty_mutex);

	unregister_chrdev_region(dev, driver->num);
	driver->ttys = NULL;
	driver->termios = NULL;
	kfree(p);
	return error;
}

Project: linux
File: tty_io.c

int tty_release(struct inode *inode, struct file *filp)
{
	struct tty_struct *tty = file_tty(filp);
	struct tty_struct *o_tty;
	int	pty_master, tty_closing, o_tty_closing, do_sleep;
	int	devpts;
	int	idx;
	char	buf[64];

	if (tty_paranoia_check(tty, inode, "tty_release_dev"))
		return 0;

	tty_lock();
	check_tty_count(tty, "tty_release_dev");

	__tty_fasync(-1, filp, 0);

	idx = tty->index;
	pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
		      tty->driver->subtype == PTY_TYPE_MASTER);
	devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
	o_tty = tty->link;

#ifdef TTY_PARANOIA_CHECK
	if (idx < 0 || idx >= tty->driver->num) {
		printk(KERN_DEBUG "tty_release_dev: bad idx when trying to "
				  "free (%s)\n", tty->name);
		tty_unlock();
		return 0;
	}
	if (!devpts) {
		if (tty != tty->driver->ttys[idx]) {
			tty_unlock();
			printk(KERN_DEBUG "tty_release_dev: driver.table[%d] not tty "
			       "for (%s)\n", idx, tty->name);
			return 0;
		}
		if (tty->termios != tty->driver->termios[idx]) {
			tty_unlock();
			printk(KERN_DEBUG "tty_release_dev: driver.termios[%d] not termios "
			       "for (%s)\n",
			       idx, tty->name);
			return 0;
		}
	}
#endif

#ifdef TTY_DEBUG_HANGUP
	printk(KERN_DEBUG "tty_release_dev of %s (tty count=%d)...",
	       tty_name(tty, buf), tty->count);
#endif

#ifdef TTY_PARANOIA_CHECK
	if (tty->driver->other &&
	     !(tty->driver->flags & TTY_DRIVER_DEVPTS_MEM)) {
		if (o_tty != tty->driver->other->ttys[idx]) {
			tty_unlock();
			printk(KERN_DEBUG "tty_release_dev: other->table[%d] "
					  "not o_tty for (%s)\n",
			       idx, tty->name);
			return 0 ;
		}
		if (o_tty->termios != tty->driver->other->termios[idx]) {
			tty_unlock();
			printk(KERN_DEBUG "tty_release_dev: other->termios[%d] "
					  "not o_termios for (%s)\n",
			       idx, tty->name);
			return 0;
		}
		if (o_tty->link != tty) {
			tty_unlock();
			printk(KERN_DEBUG "tty_release_dev: bad pty pointers\n");
			return 0;
		}
	}
#endif
	if (tty->ops->close)
		tty->ops->close(tty, filp);

	tty_unlock();
	/*
	 * Sanity check: if tty->count is going to zero, there shouldn't be
	 * any waiters on tty->read_wait or tty->write_wait.  We test the
	 * wait queues and kick everyone out _before_ actually starting to
	 * close.  This ensures that we won't block while releasing the tty
	 * structure.
	 *
	 * The test for the o_tty closing is necessary, since the master and
	 * slave sides may close in any order.  If the slave side closes out
	 * first, its count will be one, since the master side holds an open.
	 * Thus this test wouldn't be triggered at the time the slave closes,
	 * so we do it now.
	 *
	 * Note that it's possible for the tty to be opened again while we're
	 * flushing out waiters.  By recalculating the closing flags before
	 * each iteration we avoid any problems.
	 */
	while (1) {
		/* Guard against races with tty->count changes elsewhere and
		   opens on /dev/tty */

		mutex_lock(&tty_mutex);
		tty_lock();
		tty_closing = tty->count <= 1;
		o_tty_closing = o_tty &&
			(o_tty->count <= (pty_master ? 1 : 0));
		do_sleep = 0;

		if (tty_closing) {
			if (waitqueue_active(&tty->read_wait)) {
				wake_up_poll(&tty->read_wait, POLLIN);
				do_sleep++;
			}
			if (waitqueue_active(&tty->write_wait)) {
				wake_up_poll(&tty->write_wait, POLLOUT);
				do_sleep++;
			}
		}
		if (o_tty_closing) {
			if (waitqueue_active(&o_tty->read_wait)) {
				wake_up_poll(&o_tty->read_wait, POLLIN);
				do_sleep++;
			}
			if (waitqueue_active(&o_tty->write_wait)) {
				wake_up_poll(&o_tty->write_wait, POLLOUT);
				do_sleep++;
			}
		}
		if (!do_sleep)
			break;

		printk(KERN_WARNING "tty_release_dev: %s: read/write wait queue "
				    "active!\n", tty_name(tty, buf));
		tty_unlock();
		mutex_unlock(&tty_mutex);
		schedule();
	}

	/*
	 * The closing flags are now consistent with the open counts on
	 * both sides, and we've completed the last operation that could
	 * block, so it's safe to proceed with closing.
	 */
	if (pty_master) {
		if (--o_tty->count < 0) {
			printk(KERN_WARNING "tty_release_dev: bad pty slave count "
					    "(%d) for %s\n",
			       o_tty->count, tty_name(o_tty, buf));
			o_tty->count = 0;
		}
	}
	if (--tty->count < 0) {
		printk(KERN_WARNING "tty_release_dev: bad tty->count (%d) for %s\n",
		       tty->count, tty_name(tty, buf));
		tty->count = 0;
	}

	/*
	 * We've decremented tty->count, so we need to remove this file
	 * descriptor off the tty->tty_files list; this serves two
	 * purposes:
	 *  - check_tty_count sees the correct number of file descriptors
	 *    associated with this tty.
	 *  - do_tty_hangup no longer sees this file descriptor as
	 *    something that needs to be handled for hangups.
	 */
	tty_del_file(filp);

	/*
	 * Perform some housekeeping before deciding whether to return.
	 *
	 * Set the TTY_CLOSING flag if this was the last open.  In the
	 * case of a pty we may have to wait around for the other side
	 * to close, and TTY_CLOSING makes sure we can't be reopened.
	 */
	if (tty_closing)
		set_bit(TTY_CLOSING, &tty->flags);
	if (o_tty_closing)
		set_bit(TTY_CLOSING, &o_tty->flags);

	/*
	 * If _either_ side is closing, make sure there aren't any
	 * processes that still think tty or o_tty is their controlling
	 * tty.
	 */
	if (tty_closing || o_tty_closing) {
		read_lock(&tasklist_lock);
		session_clear_tty(tty->session);
		if (o_tty)
			session_clear_tty(o_tty->session);
		read_unlock(&tasklist_lock);
	}

	mutex_unlock(&tty_mutex);

	/* check whether both sides are closing ... */
	if (!tty_closing || (o_tty && !o_tty_closing)) {
		tty_unlock();
		return 0;
	}

#ifdef TTY_DEBUG_HANGUP
	printk(KERN_DEBUG "freeing tty structure...");
#endif
	/*
	 * Ask the line discipline code to release its structures
	 */
	tty_ldisc_release(tty, o_tty);
	/*
	 * The release_tty function takes care of the details of clearing
	 * the slots and preserving the termios structure.
	 */
	release_tty(tty, idx);

	/* Make this pty number available for reallocation */
	if (devpts)
		devpts_kill_index(inode, idx);
	tty_unlock();
	return 0;
}

Project: linux
File: tty_io.c

static int tty_reopen(struct tty_struct *tty)
{
	struct tty_driver *driver = tty->driver;

	if (test_bit(TTY_CLOSING, &tty->flags) ||
			test_bit(TTY_HUPPING, &tty->flags) ||
			test_bit(TTY_LDISC_CHANGING, &tty->flags))
		return -EIO;

	if (driver->type == TTY_DRIVER_TYPE_PTY &&
	    driver->subtype == PTY_TYPE_MASTER) {
		/*
		 * special case for PTY masters: only one open permitted,
		 * and the slave side open count is incremented as well.
		 */
		if (tty->count)
			return -EIO;

		tty->link->count++;
	}
	tty->count++;
	tty->driver = driver; /* N.B. why do this every time?? */

	mutex_lock(&tty->ldisc_mutex);
	WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
	mutex_unlock(&tty->ldisc_mutex);

	return 0;
}

Project: linux
File: tty_io.c

void tty_shutdown(struct tty_struct *tty)
{
	tty_driver_remove_tty(tty->driver, tty);
	tty_free_termios(tty);
}

Project: linux
File: tty_io.c

void tty_unregister_device(struct tty_driver *driver, unsigned index)
{
	device_destroy(tty_class,
		MKDEV(driver->major, driver->minor_start) + index);
}

Project: linux
File: tty_io.c

void tty_vhangup(struct tty_struct *tty)
{
#ifdef TTY_DEBUG_HANGUP
	char	buf[64];

	printk(KERN_DEBUG "%s vhangup...\n", tty_name(tty, buf));
#endif
	__tty_hangup(tty);
}

Project: linux
File: tty_io.c

static ssize_t tty_write(struct file *file, const char __user *buf,
						size_t count, loff_t *ppos)
{
	struct inode *inode = file->f_path.dentry->d_inode;
	struct tty_struct *tty = file_tty(file);
 	struct tty_ldisc *ld;
	ssize_t ret;

	if (tty_paranoia_check(tty, inode, "tty_write"))
		return -EIO;
	if (!tty || !tty->ops->write ||
		(test_bit(TTY_IO_ERROR, &tty->flags)))
			return -EIO;
	/* Short term debug to catch buggy drivers */
	if (tty->ops->write_room == NULL)
		printk(KERN_ERR "tty driver %s lacks a write_room method.\n",
			tty->driver->name);
	ld = tty_ldisc_ref_wait(tty);
	if (!ld->ops->write)
		ret = -EIO;
	else
		ret = do_tty_write(ld->ops->write, tty, file, buf, count);
	tty_ldisc_deref(ld);
	return ret;
}