netdev - [PATCH net-next 0/4] net: inet: Retire port only listening

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Date:   Wed, 11 May 2022 17:05:46 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     <netdev@...r.kernel.org>
CC:     David Miller <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>, <kernel-team@...com>,
        Paolo Abeni <pabeni@...hat.com>
Subject: [PATCH net-next 0/4] net: inet: Retire port only listening_hash

This series is to retire the port only listening_hash.

The listen sk is currently stored in two hash tables,
listening_hash (hashed by port) and lhash2 (hashed by port and address).

After commit 0ee58dad5b06 ("net: tcp6: prefer listeners bound to an address")
and commit d9fbc7f6431f ("net: tcp: prefer listeners bound to an address"),
the TCP-SYN lookup fast path does not use listening_hash.

The commit 05c0b35709c5 ("tcp: seq_file: Replace listening_hash with lhash2")
also moved the seq_file (/proc/net/tcp) iteration usage from
listening_hash to lhash2.

There are still a few listening_hash usages left.
One of them is inet_reuseport_add_sock() which uses the listening_hash
to search a listen sk during the listen() system call.  This turns
out to be very slow on use cases that listen on many different
VIPs at a popular port (e.g. 443).  [ On top of the slowness in
adding to the tail in the IPv6 case ]. A latter patch has a
selftest to demonstrate this case.

This series takes this chance to move all remaining listening_hash
usages to lhash2 and then retire listening_hash.

Martin KaFai Lau (4):
  net: inet: Remove count from inet_listen_hashbucket
  net: inet: Open code inet_hash2 and inet_unhash2
  net: inet: Retire port only listening_hash
  net: selftests: Stress reuseport listen

 include/net/inet_connection_sock.h            |   2 -
 include/net/inet_hashtables.h                 |  42 +------
 net/dccp/proto.c                              |   1 -
 net/ipv4/inet_diag.c                          |   5 +-
 net/ipv4/inet_hashtables.c                    | 119 +++++-------------
 net/ipv4/tcp.c                                |   1 -
 net/ipv4/tcp_ipv4.c                           |  21 ++--
 net/ipv6/inet6_hashtables.c                   |   5 +-
 net/mptcp/mptcp_diag.c                        |   4 +-
 tools/testing/selftests/net/Makefile          |   2 +
 .../selftests/net/stress_reuseport_listen.c   | 105 ++++++++++++++++
 .../selftests/net/stress_reuseport_listen.sh  |  25 ++++
 12 files changed, 180 insertions(+), 152 deletions(-)
 create mode 100644 tools/testing/selftests/net/stress_reuseport_listen.c
 create mode 100755 tools/testing/selftests/net/stress_reuseport_listen.sh

-- 
2.30.2