[PATCH 3.16 023/328] USB: serial: kobil_sct: fix modem-status error handling

[Ben Hutchings]

3.16.62-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Johan Hovold <jo...@kernel.org>

commit a420b5d939ee58f1d950f0ea782834056520aeaa upstream.

Make sure to return -EIO in case of a short modem-status read request.

While at it, split the debug message to not include the (zeroed)
transfer-buffer content in case of errors.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Johan Hovold <jo...@kernel.org>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 drivers/usb/serial/kobil_sct.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

--- a/drivers/usb/serial/kobil_sct.c
+++ b/drivers/usb/serial/kobil_sct.c
@@ -408,12 +408,20 @@ static int kobil_tiocmget(struct tty_str
                          transfer_buffer_length,
                          KOBIL_TIMEOUT);
 
-       dev_dbg(&port->dev, "%s - Send get_status_line_state URB returns: %i. 
Statusline: %02x\n",
-               __func__, result, transfer_buffer[0]);
+       dev_dbg(&port->dev, "Send get_status_line_state URB returns: %i\n",
+                       result);
+       if (result < 1) {
+               if (result >= 0)
+                       result = -EIO;
+               goto out_free;
+       }
+
+       dev_dbg(&port->dev, "Statusline: %02x\n", transfer_buffer[0]);
 
        result = 0;
        if ((transfer_buffer[0] & SUSBCR_GSL_DSR) != 0)
                result = TIOCM_DSR;
+out_free:
        kfree(transfer_buffer);
        return result;
 }