On Mon, 2008-05-05 at 16:03 -0700, David Miller wrote:

quoted text
> @@ -255,11 +255,12 @@ struct sk_buff *__netdev_alloc_skb(struct net_devic=
e *dev,
quoted text
>  		unsigned int length, gfp_t gfp_mask)
>  {
>  	int node =3D dev->dev.parent ? dev_to_node(dev->dev.parent) : -1;
> +	unsigned int extra =3D dev->rx_alloc_extra + NET_SKB_PAD;
>  	struct sk_buff *skb;
> =20
> -	skb =3D __alloc_skb(length + NET_SKB_PAD, gfp_mask, 0, node);
> +	skb =3D __alloc_skb(length + extra, gfp_mask, 0, node);
>  	if (likely(skb)) {
> -		skb_reserve(skb, NET_SKB_PAD);
> +		skb_reserve(skb, extra);

Come to think of it, if you want to bridge two wireless AP-mode devices
with different headroom .... Nah.

four-byte multiple isn't quite right though, but I'm not sure what would
be, probably multiple of NET_SKB_PAD?

johannes