[RFC PATCH v3 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.

This revision of the series try to address the feedback provided by Willem,
Steffen and Subash fixing several bugs all along

rfc v2 - rfc v3:
 - cope better with exceptional conditions
 - test cases cleanup

rfc v1 - rfc 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                           |  25 ++-
 include/net/udp.h                             |  51 ++++-
 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         | 147 +++++++++++++
 tools/testing/selftests/net/udpgro_bench.sh   |  94 +++++++++
 tools/testing/selftests/net/udpgso_bench.sh   |   2 +-
 tools/testing/selftests/net/udpgso_bench_rx.c | 193 ++++++++++++++++--
 tools/testing/selftests/net/udpgso_bench_tx.c |  22 +-
 tools/testing/selftests/net/xdp_dummy.c       |  13 ++
 17 files changed, 816 insertions(+), 122 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