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From 39fba7835aacda65284a86e611774cbba71dac20 Mon Sep 17 00:00:00 2001
From: Eric Dumazet <edumazet@google.com>
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 <edumazet@google.com>
Cc: James Hughes <james.hughes@raspberrypi.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
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);
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