Re: ip_gre headroom allocation

Herbert Xu wrote:

On Thu, Jun 11, 2009 at 01:17:14PM +0300, Timo Teräs wrote:

quoted

quoted

Otherwise we'd need a similar hack in ipip.c too.

I was under the impression that as we need to do the route lookup anyway
we could take advantage of the information available from there fully.

But yes, your explanation makes perfect sense.

I think you're both right :)

We should include the IPsec head room here, but also in the
dev->needed_headroom calculation so that most packets don't
get reallocated in the first place.

I guess this is easy for point-to-point tunnels. But how about the
multipoint gre tunnels? The needed_headroom can vary on destination
basis depending on if they are NATted or not, and on the cipher/hash
used.

Can we change the needed_headroom on-the-fly? Increase it when ever
we encounter a larger path? But this also means some packages would
get extra headroom allocated.

- Timo