Re: pskb change in dst->output

["David S. Miller" <davem@redhat.com>]

On Fri, 9 Jul 2004 10:02:25 -0400 (EDT)
James Morris <jmorris@redhat.com> wrote:

> On Fri, 9 Jul 2004, Herbert Xu wrote:
> 
> > On Thu, Jul 08, 2004 at 02:02:35PM +1000, herbert wrote:
> > > 
> > > That's only because the dst->output() functions are calling
> > > skb_checksum_help().  Since those same functions assume the
> > > skb to be "uncloned" anyway (they modify it directly by adding
> > > headers etc.), they only need to call a version of
> > > skb_checksum_help() that does not do a copy of the skb.
> > 
> > If there are no objections, I'd like to create a version of
> > skb_checksum_help() that doesn't copy the packet, and call
> > that version from ah_output()/esp_output()/ipcomp_output().
> 
> This will break when cloned packets are passed to these functions.

James is right Herbert.  TCP will send clones down into these routines
all the time.