Re: [Xen-devel] xennet_start_xmit assumptions

On (01/20/17 14:30), David Miller wrote:

CAP_SYS_RAWIO or not, the contract we have with the device is that
there will be at least enough bytes to cover a link layer header.

I see. If that's the case (for all the kernel-driver interfaces), 
then the xen_netfront driver is probably not required to check for
variants of sk_buffs like pure-non-linear etc.

This probably requires a little bit of an adjustment to the calling
convention.  Perhaps:

	int dev_validate_header(const struct net_device *dev,
				char *ll_header, int len);

So then you can go:

	new_len = dev_validate_header(dev, skb->data, len);
	if (new_len < 0)
		goto out_cleanup_err;
	if (new_len > len)
		__skb_put(skb, new_len - len);

Or something like that.

ok let me work with that and get back (hopefully with an 
RFC patch).

--Sowmini