[RFC PATCH v2 00/10] udp: implement GRO support

[Paolo Abeni <pabeni@redhat.com>]

This series implements GRO support for UDP sockets, as the RX counterpart
of commit bec1f6f69736 ("udp: generate gso with UDP_SEGMENT").
The core functionality is implemented by the second patch, introducing a new
sockopt to enable UDP_GRO, while patch 3 implements support for passing the
segment size to the user space via a new cmsg.
UDP GRO performs a socket lookup for each ingress packets and aggregate datagram
directed to UDP GRO enabled sockets with constant l4 tuple.

UDP GRO packets can land on non GRO-enabled sockets, e.g. due to iptables NAT
rules, and that could potentially confuse existing applications.

The solution adopted here is to de-segment the GRO packet before enqueuing
as needed. Since we must cope with packet reinsertion after de-segmentation,
the relevant code is factored-out in ipv4 and ipv6 specific helpers and exposed
to UDP usage.

While the current code can probably be improved, this safeguard ,implemented in
the patches 4-7, allows future enachements to enable UDP GSO offload on more
virtual devices eventually even on forwarded packets.

The last 4 for patches implement some performance and functional self-tests,
re-using the existing udpgso infrastructure. The problematic scenario described
above is explicitly tested.

v1 - v2:
 - use a new option to enable UDP GRO
 - use static keys to protect the UDP GRO socket lookup
 - cope with UDP GRO misdirection
 - add self-tests

Paolo Abeni (10):
  udp: implement complete book-keeping for encap_needed
  udp: implement GRO for plain UDP sockets.
  udp: add support for UDP_GRO cmsg
  ip: factor out protocol delivery helper
  ipv6: factor out protocol delivery helper
  udp: cope with UDP GRO packet misdirection
  selftests: add GRO support to udp bench rx program
  selftests: conditionally enable XDP support in udpgso_bench_rx
  selftests: add some benchmark for UDP GRO
  selftests: add functionals test for UDP GRO

 include/linux/udp.h                           |  42 +++-
 include/net/udp_tunnel.h                      |   6 +
 include/uapi/linux/udp.h                      |   1 +
 net/ipv4/ip_input.c                           |  73 ++++---
 net/ipv4/udp.c                                |  54 ++++-
 net/ipv4/udp_offload.c                        | 109 ++++++++--
 net/ipv6/ip6_input.c                          |  28 +--
 net/ipv6/udp.c                                |  44 +++-
 net/ipv6/udp_offload.c                        |   6 +-
 tools/testing/selftests/net/Makefile          |  70 +++++++
 tools/testing/selftests/net/udpgro.sh         | 144 +++++++++++++
 tools/testing/selftests/net/udpgro_bench.sh   |  94 +++++++++
 tools/testing/selftests/net/udpgso_bench.sh   |   2 +-
 tools/testing/selftests/net/udpgso_bench_rx.c | 195 ++++++++++++++++--
 tools/testing/selftests/net/udpgso_bench_tx.c |  22 +-
 tools/testing/selftests/net/xdp_dummy.c       |  13 ++
 16 files changed, 790 insertions(+), 113 deletions(-)
 create mode 100755 tools/testing/selftests/net/udpgro.sh
 create mode 100755 tools/testing/selftests/net/udpgro_bench.sh
 create mode 100644 tools/testing/selftests/net/xdp_dummy.c

-- 
2.17.2