usb: serial: mos7840: Fixup mos7840_chars_in_buffer()

commit 5c263b92f828af6a8cf54041db45ceae5af8f2ab upstream.

 * Use the buffer content length as opposed to the total buffer size.  This can
   be a real problem when using the mos7840 as a usb serial-console as all
   kernel output is truncated during boot.

Signed-off-by: Mark Ferrell <mferrell@uplogix.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 6 insertions, 3 deletions

diff --git a/drivers/usb/serial/mos7840.c b/drivers/usb/serial/mos7840.c
index fdbeb6a0e90..fd2463e6bd4 100644
--- a/drivers/usb/serial/mos7840.c
+++ b/drivers/usb/serial/mos7840.c
@@ -1191,9 +1191,12 @@ static int mos7840_chars_in_buffer(struct tty_struct *tty)
         }
 
         spin_lock_irqsave(&mos7840_port->pool_lock, flags);
-        for (i = 0; i < NUM_URBS; ++i)
-                if (mos7840_port->busy[i])
-                        chars += URB_TRANSFER_BUFFER_SIZE;
+        for (i = 0; i < NUM_URBS; ++i) {
+                if (mos7840_port->busy[i]) {
+                        struct urb *urb = mos7840_port->write_urb_pool[i];
+                        chars += urb->transfer_buffer_length;
+                }
+        }
         spin_unlock_irqrestore(&mos7840_port->pool_lock, flags);
         dbg("%s - returns %d", __func__, chars);
         return chars;