4.9-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
commit 39fba7835aacda65284a86e611774cbba71dac20 upstream.
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 Signed-off-by: Linus Walleij linus.walleij@linaro.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- 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 @@ -803,18 +803,12 @@ 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);