USB: serial: cp210x: fix tiocmget error handling

BugLink: http://bugs.launchpad.net/bugs/1642572
commit de24e0a108bc48062e1c7acaa97014bce32a919f upstream.

The current tiocmget implementation would fail to report errors up the
stack and instead leaked a few bits from the stack as a mask of
modem-status flags.

Fixes: 39a66b8d22a3 ("[PATCH] USB: CP2101 Add support for flow control")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/drivers/usb/serial/cp210x.c b/drivers/usb/serial/cp210x.c
index 6eccded3bc338dcb1940d42a4729d9685458a2d9..976195e748a355ee3c3d9694d4b4b21e910a7775 100644 (file)
--- a/drivers/usb/serial/cp210x.c
+++ b/drivers/usb/serial/cp210x.c
@@ -845,7 +845,9 @@ static int cp210x_tiocmget(struct tty_struct *tty)
        unsigned int control;
        int result;
 
-       cp210x_get_config(port, CP210X_GET_MDMSTS, &control, 1);
+       result = cp210x_get_config(port, CP210X_GET_MDMSTS, &control, 1);
+       if (result)
+               return result;
 
        result = ((control & CONTROL_DTR) ? TIOCM_DTR : 0)
                |((control & CONTROL_RTS) ? TIOCM_RTS : 0)