Message-Id: <20240418133248.56378-1-kerneljasonxing@gmail.com>
Date: Thu, 18 Apr 2024 21:32:41 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: edumazet@...gle.com,
	dsahern@...nel.org,
	matttbe@...nel.org,
	martineau@...nel.org,
	geliang@...nel.org,
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	mathieu.desnoyers@...icios.com,
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Cc: mptcp@...ts.linux.dev,
	netdev@...r.kernel.org,
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	kerneljasonxing@...il.com,
	Jason Xing <kernelxing@...cent.com>
Subject: [PATCH net-next RESEND v6 0/7] Implement reset reason mechanism to detect

From: Jason Xing <kernelxing@...cent.com>

In production, there are so many cases about why the RST skb is sent but
we don't have a very convenient/fast method to detect the exact underlying
reasons.

RST is implemented in two kinds: passive kind (like tcp_v4_send_reset())
and active kind (like tcp_send_active_reset()). The former can be traced
carefully 1) in TCP, with the help of drop reasons, which is based on
Eric's idea[1], 2) in MPTCP, with the help of reset options defined in
RFC 8684. The latter is relatively independent, which should be
implemented on our own.

In this series, I focus on the fundamental implement mostly about how
the rstreason mechnism works and give the detailed passive part as an
example, not including the active reset part. In future, we can go
further and refine those NOT_SPECIFIED reasons.

Here are some examples when tracing:
<idle>-0       [002] ..s1.  1830.262425: tcp_send_reset: skbaddr=x
        skaddr=x src=x dest=x state=x reason=NOT_SPECIFIED
<idle>-0       [002] ..s1.  1830.262425: tcp_send_reset: skbaddr=x
        skaddr=x src=x dest=x state=x reason=NO_SOCKET

[1]
Link: https://lore.kernel.org/all/CANn89iJw8x-LqgsWOeJQQvgVg6DnL5aBRLi10QN2WBdr+X4k=w@mail.gmail.com/

v6
1. add back casts, or else they are treated as error.
2. RESEND because the status of patchwork changed.

v5
Link: https://lore.kernel.org/all/20240411115630.38420-1-kerneljasonxing@gmail.com/
1. address format issue (like reverse xmas tree) (Eric, Paolo)
2. remove unnecessary casts. (Eric)
3. introduce a helper used in mptcp active reset. See patch 6. (Paolo)

v4
Link: https://lore.kernel.org/all/20240409100934.37725-1-kerneljasonxing@gmail.com/
1. passing 'enum sk_rst_reason' for readability when tracing (Antoine)

v3
Link: https://lore.kernel.org/all/20240404072047.11490-1-kerneljasonxing@gmail.com/
1. rebase (mptcp part) and address what Mat suggested.

v2
Link: https://lore.kernel.org/all/20240403185033.47ebc6a9@kernel.org/
1. rebase against the latest net-next tree



Jason Xing (7):
  net: introduce rstreason to detect why the RST is sent
  rstreason: prepare for passive reset
  rstreason: prepare for active reset
  tcp: support rstreason for passive reset
  mptcp: support rstreason for passive reset
  mptcp: introducing a helper into active reset logic
  rstreason: make it work in trace world

 include/net/request_sock.h |  4 +-
 include/net/rstreason.h    | 93 ++++++++++++++++++++++++++++++++++++++
 include/net/tcp.h          |  3 +-
 include/trace/events/tcp.h | 37 +++++++++++++--
 net/dccp/ipv4.c            | 10 ++--
 net/dccp/ipv6.c            | 10 ++--
 net/dccp/minisocks.c       |  3 +-
 net/ipv4/tcp.c             | 15 ++++--
 net/ipv4/tcp_ipv4.c        | 14 +++---
 net/ipv4/tcp_minisocks.c   |  3 +-
 net/ipv4/tcp_output.c      |  5 +-
 net/ipv4/tcp_timer.c       |  9 ++--
 net/ipv6/tcp_ipv6.c        | 17 ++++---
 net/mptcp/protocol.c       |  2 +-
 net/mptcp/protocol.h       | 11 +++++
 net/mptcp/subflow.c        | 27 ++++++++---
 16 files changed, 216 insertions(+), 47 deletions(-)
 create mode 100644 include/net/rstreason.h

-- 
2.37.3

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