On Thu, 2003-02-06 at 10:44, David S. Miller wrote:
From: Chris Leech [off-list ref]
Date: 06 Feb 2003 11:22:51 -0800
I fail to see how the statement "skb->len + skb->data_len" has any
usable meaning, or how it can be anything other than a bug.
This equation is the standard way to find the full length
on any skb. For linear skbs, data_len is always zero.
I asked Alan to use this formula so that greps on the source
tree would always show data_len being taken into account, and
thus usage would be consistent.
OK, now I'm really getting confused. Every other example I can find in
the networking code, and every scatter-gather capable driver, uses
skb->len as the full length and skb->len - skb->data_len as the length
of the first or linear portion.