On Thu, 1 Mar 2018 11:19:03 +0800
Jason Wang <jasowang@xxxxxxxxxx> wrote:
> This series tries to re-enable XDP_REDIRECT for mergeable buffer which
> was removed since commit 7324f5399b06 ("virtio_net: disable
> XDP_REDIRECT in receive_mergeable() case"). Main concerns are:
>
> - not enough tailroom was reserved which breaks cpumap
To address this at a more fundamental level, I would suggest that we/you
instead extend XDP to know it's buffers "frame" size/end. (The
assumption use to be, xdp_buff->data_hard_start + PAGE_SIZE, but
ixgbe+virtio_net broke that assumption).
It should actually be fairly easy to implement:
* Simply extend xdp_buff with a "data_hard_end" pointer.
Now cpumap is more safe... instead of crashing, it can now know/see when
it is safe to create an SKB using build_skb (could fallback to
dev_alloc_skb).
--
Best regards,
Jesper Dangaard Brouer
MSc.CS, Principal Kernel Engineer at Red Hat
LinkedIn: http://www.linkedin.com/in/brouer
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