Messages in this thread | | | Subject | Re: [RFC 1/2] net-next: add a dma_desc element to struct skb_shared_info | From | Paolo Abeni <> | Date | Fri, 21 Jul 2017 17:56:39 +0200 |
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Hi,
On Fri, 2017-07-21 at 17:20 +0200, John Crispin wrote: > In order to make HW flow offloading work in latest MediaTek silicon we need > to propagate part of the RX DMS descriptor to the upper layers populating > the flow offload engines HW tables. This patch adds an extra element to > struct skb_shared_info allowing the ethernet drivers RX napi code to store > the required information and make it persistent for the lifecycle of the > skb and its clones. > > Signed-off-by: John Crispin <john@phrozen.org> > --- > include/linux/skbuff.h | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > index 4093552be1de..db9576cd946b 100644 > --- a/include/linux/skbuff.h > +++ b/include/linux/skbuff.h > @@ -426,6 +426,7 @@ struct skb_shared_info { > unsigned int gso_type; > u32 tskey; > __be32 ip6_frag_id; > + u32 dma_desc; > > /* > * Warning : all fields before dataref are cleared in __alloc_skb()
This will increase the skb_shared_info struct size, which is already quite large, and can have several kind of performance drawback. AFAIK this is discouraged.
I don't understand the use case; the driver will set this field, but who is going to consume it?
Thanks,
Paolo
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