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>

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 17b6a62d206e0d6825b8a7b0e83794fed4930e02..c0f64392627c96b3cdc2e05f720069ba525c7e6e 100644 (file)
--- 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);