[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>

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/net/smc9194.c b/drivers/net/smc9194.c
index 6cf16f3..8b0321f 100644
--- a/drivers/net/smc9194.c
+++ b/drivers/net/smc9194.c
@@ -523,8 +523,7 @@ static int smc_wait_to_send_packet( struct sk_buff * skb, struct net_device * de
 	length = skb->len;
 
 	if (length < ETH_ZLEN) {
-		skb = skb_padto(skb, ETH_ZLEN);
-		if (skb == NULL) {
+		if (skb_padto(skb, ETH_ZLEN)) {
 			netif_wake_queue(dev);
 			return 0;
 		}