[net-next PATCH RFC 0/8] page_pool DMA handling and allow to recycles frames via SKB

[Jesper Dangaard Brouer <brouer@redhat.com>]

This RFC patchset shows the plans for allowing page_pool to handle and
maintain DMA map/unmap of the pages it serves to the driver.  For this
to work a return hook in the network core is introduced, which also
involves extending sk_buff with the necessary information.

The overall purpose is to simplify drivers, by providing a page
allocation API that does recycling, such that each driver doesn't have
to reinvent its own recycling scheme.  Using page_pool in a driver
does not require implementing XDP support, but it makes it trivially
easy to do so.  The recycles code leverage the XDP recycle APIs.

The Marvell mvneta driver was used in this patchset to demonstrate how
to use the API, and tested on the EspressoBIN board.  We also have
patches enabling XDP for this driver, but they are not part of this
patchset as we want review of the general idea of the page_pool return
SKB hook.

A driver using page_pool and XDP redirecting into CPUMAP or veth, will
also take advantage of the new SKB return hook, this is currently only mlx5.


The longer term plans involves allowing other types of allocators to
use this return hook.  Particularly allowing zero-copy AF_XDP frames
to travel further into the netstack, if userspace page have been
restricted to read-only.

---

Ilias Apalodimas (4):
      page_pool: add helper functions for DMA
      net: mvneta: use page pool API for sw buffer manager
      net: core: add recycle capabilities on skbs via page_pool API
      net: mvneta: remove copybreak, prefetch and use build_skb

Jesper Dangaard Brouer (4):
      xdp: reduce size of struct xdp_mem_info
      mvneta: activate page recycling via skb using page_pool
      xdp: bpf: cpumap redirect must update skb->mem_info
      veth: xdp_frames redirected into veth need to transfer xdp_mem_info


 drivers/net/ethernet/marvell/Kconfig  |    1 
 drivers/net/ethernet/marvell/mvneta.c |  158 +++++++++++++++++----------------
 drivers/net/veth.c                    |    1 
 include/linux/skbuff.h                |    6 +
 include/net/page_pool.h               |    6 +
 include/net/xdp.h                     |    5 +
 kernel/bpf/cpumap.c                   |    2 
 net/core/page_pool.c                  |    7 +
 net/core/skbuff.c                     |    7 +
 net/core/xdp.c                        |   14 ++-
 10 files changed, 125 insertions(+), 82 deletions(-)