On Tue, Jun 24, 2008 at 4:50 AM, Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:

On Mon, 2008-06-23 at 14:55 +0200, Stefan Roese wrote:
> From: Sathya Narayanan <sathyan@teamf1.com>
>
> Short packets has to be discarded by the driver. So this patch addresses the
> issue of discarding the short packets of size lesser then ethernet header
> size.

You are freeing the skb, why ? Shouldn't we just keep the skb in the
ring for further rx ?

Actually , short packets are not allowed to flow through the higher layers, If any of the layer tried to use the extra room available may hit wit crash .
Since it is a invalid packet it has to be dropped and freed in driver.
Actually if you see in code, the other invalid packets are also handelled similar.

> Signed-off-by: Sathya Narayanan <sathyan@teamf1.com>
> Signed-off-by: Stefan Roese <sr@denx.de>
> ---
> drivers/net/ibm_newemac/core.c | 7 +++++++
> 1 files changed, 7 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/net/ibm_newemac/core.c b/drivers/net/ibm_newemac/core.c
> index 6dfc2c9..aa407b2 100644
> --- a/drivers/net/ibm_newemac/core.c
> +++ b/drivers/net/ibm_newemac/core.c
> @@ -1652,6 +1652,13 @@ static int emac_poll_rx(void *param, int budget)
>
> skb_put(skb, len);
> push_packet:
> + if (skb->len < ETH_HLEN) {
> + dev_kfree_skb(skb);
> + printk(KERN_WARNING "%s: short packets dropped\n",
> + dev->ndev->name);
> + ++dev->estats.rx_dropped_stack;
> + goto next;
> + }
> skb->dev = dev->ndev;
> skb->protocol = eth_type_trans(skb, dev->ndev);
> emac_rx_csum(dev, skb, ctrl);