USB: ftdi_sio: fix legacy SIO-device header

Length field of header was incorrectly set to available payload space
rather than the actual payload size.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1 insertions, 1 deletions

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 97f2d9c1edd6..050211afc07e 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1752,10 +1752,10 @@ static int ftdi_prepare_write_buffer(struct usb_serial_port *port,
                 spin_lock_irqsave(&port->lock, flags);
                 for (i = 0; i < size - 1; i += priv->max_packet_size) {
                         len = min_t(int, size - i, priv->max_packet_size) - 1;
-                        buffer[i] = (len << 2) + 1;
                         c = kfifo_out(&port->write_fifo, &buffer[i + 1], len);
                         if (!c)
                                 break;
+                        buffer[i] = (c << 2) + 1;
                         count += c + 1;
                 }
                 spin_unlock_irqrestore(&port->lock, flags);