[PATCH net-next 0/6] Implement reset reason mechanism to detect

From: Jason Xing <kerneljasonxing@gmail.com>
To: edumazet@google.com, mhiramat@kernel.org,
	mathieu.desnoyers@efficios.com, rostedt@goodmis.org,
	kuba@kernel.org, pabeni@redhat.com, davem@davemloft.net,
	matttbe@kernel.org, martineau@kernel.org, geliang@kernel.org
Cc: mptcp@lists.linux.dev, netdev@vger.kernel.org,
	linux-trace-kernel@vger.kernel.org, kerneljasonxing@gmail.com,
	Jason Xing <kernelxing@tencent.com>
Subject: [PATCH net-next 0/6] Implement reset reason mechanism to detect
Date: Thu,  4 Apr 2024 15:20:41 +0800	[thread overview]
Message-ID: <20240404072047.11490-1-kerneljasonxing@gmail.com> (raw)

From: Jason Xing <kernelxing@tencent.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 and the detailed passive part works 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/

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

Jason Xing (6):
  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
  rstreason: make it work in trace world

 include/net/request_sock.h |  3 +-
 include/net/rstreason.h    | 93 ++++++++++++++++++++++++++++++++++++++
 include/net/tcp.h          |  2 +-
 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      |  4 +-
 net/ipv4/tcp_timer.c       |  9 ++--
 net/ipv6/tcp_ipv6.c        | 17 ++++---
 net/mptcp/protocol.c       |  4 +-
 net/mptcp/subflow.c        | 33 ++++++++++----
 15 files changed, 209 insertions(+), 48 deletions(-)
 create mode 100644 include/net/rstreason.h

-- 
2.37.3