[RFC net-next 00/27] net and/or udp optimisations

[Pavel Begunkov <asml.silence@gmail.com>]

A mix of various net optimisations, which were mostly discovered during UDP
testing. Benchmarked with an io_uring test using 16B UDP/IPv6 over dummy netdev:
2090K vs 2229K tx/s, +6.6%, or in a 4-8% range if not averaging across reboots.

1-3 removes extra atomics and barriers from sock_wfree() mainly benefitting UDP.
4-7 cleans up some zerocopy helpers
8-16 do inlining of ipv6 and generic net pathes
17 is a small nice performance improvement for TCP zerocopy
18-27 refactors UDP to shed some more overhead

Pavel Begunkov (27):
  sock: deduplicate ->sk_wmem_alloc check
  sock: optimise sock_def_write_space send refcounting
  sock: optimise sock_def_write_space barriers
  skbuff: drop zero check from skb_zcopy_set
  skbuff: drop null check from skb_zcopy
  net: xen: set zc flags only when there is ubuf
  skbuff: introduce skb_is_zcopy()
  skbuff: optimise alloc_skb_with_frags()
  net: inline sock_alloc_send_skb
  net: inline part of skb_csum_hwoffload_help
  net: inline skb_zerocopy_iter_dgram
  ipv6: inline ip6_local_out()
  ipv6: help __ip6_finish_output() inlining
  ipv6: refactor ip6_finish_output2()
  net: inline dev_queue_xmit()
  ipv6: partially inline fl6_update_dst()
  tcp: optimise skb_zerocopy_iter_stream()
  net: optimise ipcm6 cookie init
  udp/ipv6: refactor udpv6_sendmsg udplite checks
  udp/ipv6: move pending section of udpv6_sendmsg
  udp/ipv6: prioritise the ip6 path over ip4 checks
  udp/ipv6: optimise udpv6_sendmsg() daddr checks
  udp/ipv6: optimise out daddr reassignment
  udp/ipv6: clean up udpv6_sendmsg's saddr init
  ipv6: refactor opts push in __ip6_make_skb()
  ipv6: improve opt-less __ip6_make_skb()
  ipv6: clean up ip6_setup_cork

 drivers/net/xen-netback/interface.c |   3 +-
 include/linux/netdevice.h           |  27 ++++-
 include/linux/skbuff.h              | 102 +++++++++++++-----
 include/net/ipv6.h                  |  37 ++++---
 include/net/sock.h                  |  10 +-
 net/core/datagram.c                 |   2 -
 net/core/datagram.h                 |  15 ---
 net/core/dev.c                      |  28 ++---
 net/core/skbuff.c                   |  59 ++++-------
 net/core/sock.c                     |  50 +++++++--
 net/ipv4/ip_output.c                |  10 +-
 net/ipv4/tcp.c                      |   5 +-
 net/ipv6/datagram.c                 |   4 +-
 net/ipv6/exthdrs.c                  |  15 ++-
 net/ipv6/ip6_output.c               |  88 ++++++++--------
 net/ipv6/output_core.c              |  12 ---
 net/ipv6/raw.c                      |   8 +-
 net/ipv6/udp.c                      | 158 +++++++++++++---------------
 net/l2tp/l2tp_ip6.c                 |   8 +-
 19 files changed, 339 insertions(+), 302 deletions(-)
 delete mode 100644 net/core/datagram.h

-- 
2.35.1