USB: serial: add special case for processing of empty read urbs

Return immediately from generic process_read_urb if urb is empty.

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

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index fcd30b841559..a817ced82835 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -324,6 +324,9 @@ void usb_serial_generic_process_read_urb(struct urb *urb)
         char *ch = (char *)urb->transfer_buffer;
         int i;
 
+        if (!urb->actual_length)
+                return;
+
         tty = tty_port_tty_get(&port->port);
         if (!tty)
                 return;