Re: Resurrecting due to huge ipoib perf regression - [BUG] skb corruption and kernel panic at forwarding with fragmentation

[Roland Dreier]

On Fri, Jul 8, 2016 at 9:51 AM, Jason Gunthorpe
<jgunthorpe@xxxxxxxxxxxxxxxxxxxx> wrote:
> So, it appears, the dst and neigh can be used for all performances cases.
>
> For the non performance dst == null case, can we just burn cycles and
> stuff the daddr in front of the packet at hardheader time, even if we
> have to copy?

OK, sounds interesting.

Unfortunately the scope of this work has gotten to the point where I
can't take it on right now.  My system is running 4.4.y for now
(before struct skb_gso_cb grew) so I think shrinking struct skb_gso_cb
to 8 bytes plus changing SKB_SGO_CB_OFFSET to 20 will work for now.
Hope someone is able to come up with a real fix before I need to
upgrade to 4.10.y...

 - R.