From 39fba7835aacda65284a86e611774cbba71dac20 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Wed, 19 Apr 2017 09:59:26 -0700 Subject: [PATCH] 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 Cc: James Hughes Signed-off-by: David S. Miller --- drivers/net/usb/kaweth.c | 18 ++++++------------ 1 file changed, 6 insertions(+), 12 deletions(-) --- a/drivers/net/usb/kaweth.c +++ b/drivers/net/usb/kaweth.c @@ -812,18 +812,12 @@ static netdev_tx_t kaweth_start_xmit(str } /* 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);