1 files changed, 21 insertions, 6 deletions

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index 7b331e6..bf94e10 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1241,7 +1241,9 @@ static int build_dma_sg(const struct sk_buff *skb, struct urb *urb)
 	if (num_sgs == 1)
 		return 0;
 
-	urb->sg = kmalloc(num_sgs * sizeof(struct scatterlist), GFP_ATOMIC);
+	/* reserve one for zero packet */
+	urb->sg = kmalloc((num_sgs + 1) * sizeof(struct scatterlist),
+			  GFP_ATOMIC);
 	if (!urb->sg)
 		return -ENOMEM;
 
@@ -1305,7 +1307,7 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
 		if (build_dma_sg(skb, urb) < 0)
 			goto drop;
 	}
-	entry->length = length = urb->transfer_buffer_length;
+	length = urb->transfer_buffer_length;
 
 	/* don't assume the hardware handles USB_ZERO_PACKET
 	 * NOTE:  strictly conforming cdc-ether devices should expect
@@ -1317,15 +1319,18 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
 	if (length % dev->maxpacket == 0) {
 		if (!(info->flags & FLAG_SEND_ZLP)) {
 			if (!(info->flags & FLAG_MULTI_PACKET)) {
-				urb->transfer_buffer_length++;
-				if (skb_tailroom(skb)) {
+				length++;
+				if (skb_tailroom(skb) && !urb->num_sgs) {
 					skb->data[skb->len] = 0;
 					__skb_put(skb, 1);
-				}
+				} else if (urb->num_sgs)
+					sg_set_buf(&urb->sg[urb->num_sgs++],
+							dev->padding_pkt, 1);
 			}
 		} else
 			urb->transfer_flags |= URB_ZERO_PACKET;
 	}
+	entry->length = urb->transfer_buffer_length = length;
 
 	spin_lock_irqsave(&dev->txq.lock, flags);
 	retval = usb_autopm_get_interface_async(dev->intf);
@@ -1509,6 +1514,7 @@ void usbnet_disconnect (struct usb_interface *intf)
 
 	usb_kill_urb(dev->interrupt);
 	usb_free_urb(dev->interrupt);
+	kfree(dev->padding_pkt);
 
 	free_netdev(net);
 }
@@ -1679,9 +1685,16 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
 	/* initialize max rx_qlen and tx_qlen */
 	usbnet_update_max_qlen(dev);
 
+	if (dev->can_dma_sg && !(info->flags & FLAG_SEND_ZLP) &&
+		!(info->flags & FLAG_MULTI_PACKET)) {
+		dev->padding_pkt = kzalloc(1, GFP_KERNEL);
+		if (!dev->padding_pkt)
+			goto out4;
+	}
+
 	status = register_netdev (net);
 	if (status)
-		goto out4;
+		goto out5;
 	netif_info(dev, probe, dev->net,
 		   "register '%s' at usb-%s-%s, %s, %pM\n",
 		   udev->dev.driver->name,
@@ -1699,6 +1712,8 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod)
 
 	return 0;
 
+out5:
+	kfree(dev->padding_pkt);
 out4:
 	usb_free_urb(dev->interrupt);
 out3: