[RFC, PATCH 0/2, net-next] net: netsec: Add XDP Support

[Ilias Apalodimas <ilias.apalodimas@linaro.org>]

This is a respin of https://www.spinics.net/lists/netdev/msg526066.html
Since page_pool API fixes are merged into net-next we can now safely use 
it's DMA mapping capabilities. 

The first patch changes the buffer allocation from netdev_alloc_frag() 
to page_pool API. Although this will lead to slightly reduced performance 
(on raw packet drops only) we can use the API for XDP buffer recycling. 
Another side effect is a slight increase in memory usage, due to using a 
single page per packet.

The second patch adds XDP support on the driver. 
There's a bunch of interesting options that come up due to the single 
Tx queue.
Use of locking (to avoid messing up the Tx queue since ndo_xdp_xmit
and the normal stack can co-exist) is one thing. 
We also need to track down the 'buffer type' for TX and properly free or 
recycle the packet depending on it's nature. Since we use page_pool API in 
the XDP_TX case the buffers are already mapped for us and we only need to 
sync them, while on the ndo_xdp_xmit we need to map and send them

Ilias Apalodimas (2):
  net: netsec: Use page_pool API
  net: netsec: add XDP support

 drivers/net/ethernet/socionext/Kconfig  |   1 +
 drivers/net/ethernet/socionext/netsec.c | 459 ++++++++++++++++++++----
 2 files changed, 394 insertions(+), 66 deletions(-)

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2.20.1