[NET]: Avoid allocating skb in skb_pad
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>
diff --git a/drivers/net/82596.c b/drivers/net/82596.c
index da0c878..8a9f7d6 100644
--- a/drivers/net/82596.c
+++ b/drivers/net/82596.c
@@ -1070,8 +1070,7 @@
skb->len, (unsigned int)skb->data));
if (skb->len < ETH_ZLEN) {
- skb = skb_padto(skb, ETH_ZLEN);
- if (skb == NULL)
+ if (skb_padto(skb, ETH_ZLEN))
return 0;
length = ETH_ZLEN;
}