NET: usb: Adding URB_ZERO_PACKET flag to usbnet.c

This patch adds setting of the urb transfer flag URB_ZERO_PACKET  before
submitting an urb for drivers that have requested it (by advertising flag
FLAG_SEND_ZLP).
The modification is in usbnet.c function usbnet_start_xmit().
This patch only adds the zero length flag.
A subsequent patch will address the buggy code we found when devices do not
advertise FLAG_SEND_ZLP in which case there is a possibility of transferring
packets with non-deterministic length.

This patch has been tested on kernel-2.6.34-rc3.
This patch has been checked against net-2.6 tree.
Signed-off-by: Elina Pasheva <epasheva@sierrawireless.com>
Signed-off-by: Rory Filer <rfiler@sierrawireless.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 9 insertions, 6 deletions

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 17b6a62d206e..c0f64392627c 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1068,12 +1068,15 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
          * NOTE:  strictly conforming cdc-ether devices should expect
          * the ZLP here, but ignore the one-byte packet.
          */
-        if (!(info->flags & FLAG_SEND_ZLP) && (length % dev->maxpacket) == 0) {
-                urb->transfer_buffer_length++;
-                if (skb_tailroom(skb)) {
-                        skb->data[skb->len] = 0;
-                        __skb_put(skb, 1);
-                }
+        if (length % dev->maxpacket == 0) {
+                if (!(info->flags & FLAG_SEND_ZLP)) {
+                        urb->transfer_buffer_length++;
+                        if (skb_tailroom(skb)) {
+                                skb->data[skb->len] = 0;
+                                __skb_put(skb, 1);
+                        }
+                } else
+                        urb->transfer_flags |= URB_ZERO_PACKET;
         }
 
         spin_lock_irqsave(&dev->txq.lock, flags);