USB: serial: do not forward USB specific errors in write

Use usb_translate_errors() to map USB-specific errors to errors
appropriate for user space (ENOMEM, ENODEV and EIO) in write.

Currently almost all serial drivers simply forward error codes from the
stack (e.g. from usb_submit_urb()), but these codes often have
different meanings in user-space. Doing the mapping in usb-serial core
simplifies driver code and allows for more consistent error reporting.
Signed-off-by: NJohan Hovold <jhovold@gmail.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/usb/serial/usb-serial.c

@@ -364,6 +364,8 @@ static int serial_write(struct tty_struct *tty, const unsigned char *buf,
 
 	/* pass on to the driver specific version of this function */
 	retval = port->serial->type->write(tty, port, buf, count);
+	if (retval < 0)
+		retval = usb_translate_errors(retval);
 exit:
 	return retval;
 }