USB: ftdi_sio: switch to generic TIOCMIWAIT implementation

Switch to the generic TIOCMIWAIT implementation which does not suffer
from the races involved when using the deprecated sleep_on functions.
Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/ftdi_sio.c

@@ -954,6 +954,7 @@ static struct usb_serial_driver ftdi_sio_device = {
 	.prepare_write_buffer =	ftdi_prepare_write_buffer,
 	.tiocmget =		ftdi_tiocmget,
 	.tiocmset =		ftdi_tiocmset,
+	.tiocmiwait =		usb_serial_generic_tiocmiwait,
 	.get_icount =           ftdi_get_icount,
 	.ioctl =		ftdi_ioctl,
 	.set_termios =		ftdi_set_termios,
@@ -1824,8 +1825,6 @@ static int ftdi_sio_port_remove(struct usb_serial_port *port)
 {
 	struct ftdi_private *priv = usb_get_serial_port_data(port);
 
-	wake_up_interruptible(&port->delta_msr_wait);
-
 	remove_sysfs_attrs(port);
 
 	kfree(priv);
@@ -1953,7 +1952,7 @@ static int ftdi_process_packet(struct usb_serial_port *port,
 		if (diff_status & FTDI_RS0_RLSD)
 			port->icount.dcd++;
 
-		wake_up_interruptible(&port->delta_msr_wait);
+		wake_up_interruptible(&port->port.delta_msr_wait);
 		priv->prev_status = status;
 	}
 
@@ -2376,8 +2375,6 @@ static int ftdi_ioctl(struct tty_struct *tty,
 					unsigned int cmd, unsigned long arg)
 {
 	struct usb_serial_port *port = tty->driver_data;
-	struct async_icount cnow;
-	struct async_icount cprev;
 
 	dev_dbg(&port->dev, "%s cmd 0x%04x\n", __func__, cmd);
 
@@ -2391,35 +2388,6 @@ static int ftdi_ioctl(struct tty_struct *tty,
 	case TIOCSSERIAL: /* sets serial port data */
 		return set_serial_info(tty, port,
 					(struct serial_struct __user *) arg);
-
-	/*
-	 * Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
-	 * - mask passed in arg for lines of interest
-	 *   (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
-	 * Caller should use TIOCGICOUNT to see which one it was.
-	 *
-	 * This code is borrowed from linux/drivers/char/serial.c
-	 */
-	case TIOCMIWAIT:
-		cprev = port->icount;
-		for (;;) {
-			interruptible_sleep_on(&port->delta_msr_wait);
-			/* see if a signal did it */
-			if (signal_pending(current))
-				return -ERESTARTSYS;
-
-			if (port->serial->disconnected)
-				return -EIO;
-
-			cnow = port->icount;
-			if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
-			    ((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
-			    ((arg & TIOCM_CD)  && (cnow.dcd != cprev.dcd)) ||
-			    ((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {
-				return 0;
-			}
-			cprev = cnow;
-		}
 	case TIOCSERGETLSR:
 		return get_lsr_info(port, (struct serial_struct __user *)arg);
 		break;