kaweth: use skb_cow_head() to deal with cloned skbs

We can use skb_cow_head() to properly deal with clones,
especially the ones coming from TCP stack that allow their head being
modified. This avoids a copy.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: James Hughes <james.hughes@raspberrypi.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 12 deletions

diff --git a/drivers/net/usb/kaweth.c b/drivers/net/usb/kaweth.c
index 876f02f4945e..2a2c3edb6bad 100644
--- a/drivers/net/usb/kaweth.c
+++ b/drivers/net/usb/kaweth.c
@@ -803,18 +803,12 @@ static netdev_tx_t kaweth_start_xmit(struct sk_buff *skb,
         }
 
         /* We now decide whether we can put our special header into the sk_buff */
-        if (skb_cloned(skb) || skb_headroom(skb) < 2) {
-                /* no such luck - we make our own */
-                struct sk_buff *copied_skb;
-                copied_skb = skb_copy_expand(skb, 2, 0, GFP_ATOMIC);
-                dev_kfree_skb_irq(skb);
-                skb = copied_skb;
-                if (!copied_skb) {
-                        kaweth->stats.tx_errors++;
-                        netif_start_queue(net);
-                        spin_unlock_irq(&kaweth->device_lock);
-                        return NETDEV_TX_OK;
-                }
+        if (skb_cow_head(skb, 2)) {
+                kaweth->stats.tx_errors++;
+                netif_start_queue(net);
+                spin_unlock_irq(&kaweth->device_lock);
+                dev_kfree_skb_any(skb);
+                return NETDEV_TX_OK;
         }
 
         private_header = (__le16 *)__skb_push(skb, 2);