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Commit 320348c8 authored by Alan Stern's avatar Alan Stern Committed by Live-CD User
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usb-serial: straighten out serial_open 



This patch (as1291) removes a bunch of code from serial_open(), things
that were rendered unnecessary by earlier patches.  A missing spinlock
is added to protect port->port.count, which needs to be incremented
even if the open fails but not if the tty has gotten a hangup.  The
test for whether the hardware has been initialized, based on the use
count, is replaced by a more transparent test of the
ASYNCB_INITIALIZED bit in the port flags.

Signed-off-by: default avatarAlan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@suse.de>
parent ff8324df

drivers/usb/serial/usb-serial.c

+22 −37
Original line number Diff line number Diff line
@@ -247,53 +247,38 @@ static int serial_install(struct tty_driver *driver, struct tty_struct *tty) 


static int serial_open(struct tty_struct *tty, struct file *filp)

{

	struct usb_serial *serial;

	struct usb_serial_port *port;

	int retval = 0;

	int first = 0;



	port = tty->driver_data;

	serial = port->serial;

	struct usb_serial_port *port = tty->driver_data;

	struct usb_serial *serial = port->serial;

	int retval;



	dbg("%s - port %d", __func__, port->number);



	if (mutex_lock_interruptible(&port->mutex))

		return -ERESTARTSYS;



	spin_lock_irq(&port->port.lock);

	if (!tty_hung_up_p(filp))

		++port->port.count;

	spin_unlock_irq(&port->port.lock);

	tty_port_tty_set(&port->port, tty);



	/* If the console is attached, the device is already open */

	if (port->port.count == 1 && !port->console) {

		first = 1;

	/* Do the device-specific open only if the hardware isn't

	 * already initialized.

	 */

	if (!test_bit(ASYNCB_INITIALIZED, &port->port.flags)) {

		if (mutex_lock_interruptible(&port->mutex))

			return -ERESTARTSYS;

		mutex_lock(&serial->disc_mutex);



		/* only call the device specific open if this

		 * is the first time the port is opened */

		retval = serial->type->open(tty, port);

		if (retval)

			goto bailout_module_put;

		if (serial->disconnected)

			retval = -ENODEV;

		else

			retval = port->serial->type->open(tty, port);

		mutex_unlock(&serial->disc_mutex);

		mutex_unlock(&port->mutex);

		if (retval)

			return retval;

		set_bit(ASYNCB_INITIALIZED, &port->port.flags);

	}

	mutex_unlock(&port->mutex);



	/* Now do the correct tty layer semantics */

	retval = tty_port_block_til_ready(&port->port, tty, filp);

	if (retval == 0) {

		if (!first)

			usb_serial_put(serial);

		return 0;

	}

	mutex_lock(&port->mutex);

	if (first == 0)

		goto bailout_mutex_unlock;

	/* Undo the initial port actions */

	mutex_lock(&serial->disc_mutex);

bailout_module_put:

	mutex_unlock(&serial->disc_mutex);

bailout_mutex_unlock:

	port->port.count = 0;

	mutex_unlock(&port->mutex);

	return retval;

}