USB: keyspan: fix tty line-status reporting

Fix handling of TTY error flags, which are not bitmasks and must
specifically not be ORed together as this prevents the line discipline
from recognising them.

Also insert null characters when reporting overrun errors as these are
not associated with the received character.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
diff --git a/drivers/usb/serial/keyspan.c b/drivers/usb/serial/keyspan.c
index 93cb7ce..7799d8b 100644
--- a/drivers/usb/serial/keyspan.c
+++ b/drivers/usb/serial/keyspan.c
@@ -321,14 +321,19 @@
 			/* some bytes had errors, every byte has status */
 			dev_dbg(&port->dev, "%s - RX error!!!!\n", __func__);
 			for (i = 0; i + 1 < urb->actual_length; i += 2) {
-				int stat = data[i], flag = 0;
-				if (stat & RXERROR_OVERRUN)
-					flag |= TTY_OVERRUN;
-				if (stat & RXERROR_FRAMING)
-					flag |= TTY_FRAME;
-				if (stat & RXERROR_PARITY)
-					flag |= TTY_PARITY;
+				int stat = data[i];
+				int flag = TTY_NORMAL;
+
+				if (stat & RXERROR_OVERRUN) {
+					tty_insert_flip_char(&port->port, 0,
+								TTY_OVERRUN);
+				}
 				/* XXX should handle break (0x10) */
+				if (stat & RXERROR_PARITY)
+					flag = TTY_PARITY;
+				else if (stat & RXERROR_FRAMING)
+					flag = TTY_FRAME;
+
 				tty_insert_flip_char(&port->port, data[i+1],
 						flag);
 			}
@@ -649,14 +654,19 @@
 		} else {
 			/* some bytes had errors, every byte has status */
 			for (i = 0; i + 1 < urb->actual_length; i += 2) {
-				int stat = data[i], flag = 0;
-				if (stat & RXERROR_OVERRUN)
-					flag |= TTY_OVERRUN;
-				if (stat & RXERROR_FRAMING)
-					flag |= TTY_FRAME;
-				if (stat & RXERROR_PARITY)
-					flag |= TTY_PARITY;
+				int stat = data[i];
+				int flag = TTY_NORMAL;
+
+				if (stat & RXERROR_OVERRUN) {
+					tty_insert_flip_char(&port->port, 0,
+								TTY_OVERRUN);
+				}
 				/* XXX should handle break (0x10) */
+				if (stat & RXERROR_PARITY)
+					flag = TTY_PARITY;
+				else if (stat & RXERROR_FRAMING)
+					flag = TTY_FRAME;
+
 				tty_insert_flip_char(&port->port, data[i+1],
 						flag);
 			}
@@ -713,15 +723,19 @@
 			 */
 			for (x = 0; x + 1 < len &&
 				    i + 1 < urb->actual_length; x += 2) {
-				int stat = data[i], flag = 0;
+				int stat = data[i];
+				int flag = TTY_NORMAL;
 
-				if (stat & RXERROR_OVERRUN)
-					flag |= TTY_OVERRUN;
-				if (stat & RXERROR_FRAMING)
-					flag |= TTY_FRAME;
-				if (stat & RXERROR_PARITY)
-					flag |= TTY_PARITY;
+				if (stat & RXERROR_OVERRUN) {
+					tty_insert_flip_char(&port->port, 0,
+								TTY_OVERRUN);
+				}
 				/* XXX should handle break (0x10) */
+				if (stat & RXERROR_PARITY)
+					flag = TTY_PARITY;
+				else if (stat & RXERROR_FRAMING)
+					flag = TTY_FRAME;
+
 				tty_insert_flip_char(&port->port, data[i+1],
 						     flag);
 				i += 2;
@@ -784,14 +798,20 @@
 			/* some bytes had errors, every byte has status */
 				dev_dbg(&port->dev, "%s - RX error!!!!\n", __func__);
 				for (i = 0; i + 1 < urb->actual_length; i += 2) {
-					int stat = data[i], flag = 0;
-					if (stat & RXERROR_OVERRUN)
-						flag |= TTY_OVERRUN;
-					if (stat & RXERROR_FRAMING)
-						flag |= TTY_FRAME;
-					if (stat & RXERROR_PARITY)
-						flag |= TTY_PARITY;
+					int stat = data[i];
+					int flag = TTY_NORMAL;
+
+					if (stat & RXERROR_OVERRUN) {
+						tty_insert_flip_char(
+								&port->port, 0,
+								TTY_OVERRUN);
+					}
 					/* XXX should handle break (0x10) */
+					if (stat & RXERROR_PARITY)
+						flag = TTY_PARITY;
+					else if (stat & RXERROR_FRAMING)
+						flag = TTY_FRAME;
+
 					tty_insert_flip_char(&port->port,
 							data[i+1], flag);
 				}