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[NET]: Avoid allocating skb in skb_pad

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First of all it is unnecessary to allocate a new skb in skb_pad since
the existing one is not shared.  More importantly, our hard_start_xmit
interface does not allow a new skb to be allocated since that breaks
requeueing.

This patch uses pskb_expand_head to expand the existing skb and linearize
it if needed.  Actually, someone should sift through every instance of
skb_pad on a non-linear skb as they do not fit the reasons why this was
originally created.

Incidentally, this fixes a minor bug when the skb is cloned (tcpdump,
TCP, etc.).  As it is skb_pad will simply write over a cloned skb.  Because
of the position of the write it is unlikely to cause problems but still
it's best if we don't do it.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Herbert Xu
2006-06-23 02:06:41 -07:00
committed by David S. Miller
parent 5fa21d821f
commit 5b057c6b1a
36 changed files with 74 additions and 103 deletions
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7
drivers/net/via-rhine.c
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@ -1284,11 +1284,8 @@ static int rhine_start_tx(struct sk_buff *skb, struct net_device *dev)
/* Calculate the next Tx descriptor entry. */
entry = rp->cur_tx % TX_RING_SIZE;
if (skb->len < ETH_ZLEN) {
skb = skb_padto(skb, ETH_ZLEN);
if (skb == NULL)
return 0;
}
if (skb_padto(skb, ETH_ZLEN))
return 0;
rp->tx_skbuff[entry] = skb;