linux-kernel - [RFC PATCH -tip 0/6] net: tcp: sctp: dccp: Replace jprobe usage with trace events

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Date:   Wed,  8 Nov 2017 19:00:02 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Ingo Molnar <mingo@...nel.org>,
        Ian McDonald <ian.mcdonald@...di.co.nz>,
        Vlad Yasevich <vyasevich@...il.com>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Steven Rostedt <rostedt@...dmis.org>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        "H . Peter Anvin" <hpa@...or.com>,
        Gerrit Renker <gerrit@....abdn.ac.uk>,
        "David S . Miller" <davem@...emloft.net>,
        Neil Horman <nhorman@...driver.com>, dccp@...r.kernel.org,
        netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
        Stephen Rothwell <sfr@...b.auug.org.au>
Subject: [RFC PATCH -tip 0/6] net: tcp: sctp: dccp: Replace jprobe usage with trace events

Hi,

This series introduce new trace events which allows user to
trace network congestion window etc. via ftrace or perftools.
And remove jprobe usages (tcp_probe/dccp_probe/sctp_probe).
So this series removes all register_jprobe users from the kernel
tree.

So following example in

https://wiki.linuxfoundation.org/networking/tcpprobe

 # modprobe tcp_probe port=5001
 # cat /proc/net/tcpprobe >/tmp/data.out &
 # pid=$!
 # iperf -c otherhost
 # kill $pid

will be changed as below;

 # cd <debugfs or tracefs>/tracing
 # echo 1 > events/tcp/tcp_probe/enable
 # echo "sport == 5001 || dport == 5001"  > events/tcp/tcp_probe/filter
 # tail -f trace_pipe > /tmp/data.out &
 # pid=$!
 # iperf -c otherhost
 # kill $pid

And it outouts logs lile below;

# tracer: nop
#
#                              _-----=> irqs-off
#                             / _----=> need-resched
#                            | / _---=> hardirq/softirq
#                            || / _--=> preempt-depth
#                            ||| /     delay
#           TASK-PID   CPU#  ||||    TIMESTAMP  FUNCTION
#              | |       |   ||||       |         |
          <idle>-0     [000] ..s2  1089.238049: tcp_probe: src=[::ffff:192.168.139.2]:5001 dest=[::ffff:192.168.139.1]:56256 mark=0x0 length=37 snd_nxt=0xee4abe9c snd_una=0xee4abe9c snd_cwnd=10 ssthresh=2147483647 snd_wnd=29312 srtt=478 rcv_wnd=28960
          <idle>-0     [000] ..s2  1090.156938: tcp_probe: src=[::ffff:192.168.139.2]:5001 dest=[::ffff:192.168.139.1]:56256 mark=0x0 length=37 snd_nxt=0xee4abe9c snd_una=0xee4abe9c snd_cwnd=10 ssthresh=2147483647 snd_wnd=29312 srtt=478 rcv_wnd=28992
          <idle>-0     [000] ..s2  1091.333729: tcp_probe: src=[::ffff:192.168.139.2]:5001 dest=[::ffff:192.168.139.1]:56256 mark=0x0 length=38 snd_nxt=0xee4abe9c snd_una=0xee4abe9c snd_cwnd=10 ssthresh=2147483647 snd_wnd=29312 srtt=478 rcv_wnd=28992
          <idle>-0     [000] ..s2  1092.300330: tcp_probe: src=[::ffff:192.168.139.2]:5001 dest=[::ffff:192.168.139.1]:56256 mark=0x0 length=37 snd_nxt=0xee4abe9c snd_una=0xee4abe9c snd_cwnd=10 ssthresh=2147483647 snd_wnd=29312 srtt=478 rcv_wnd=28992
          <idle>-0     [000] ..s2  1095.044739: tcp_probe: src=[::ffff:192.168.139.2]:5001 dest=[::ffff:192.168.139.1]:56256 mark=0x0 length=36 snd_nxt=0xee4abe9c snd_una=0xee4abe9c snd_cwnd=10 ssthresh=2147483647 snd_wnd=29312 srtt=478 rcv_wnd=28992
          <idle>-0     [000] ..s2  1096.573825: tcp_probe: src=[::ffff:192.168.139.2]:5001 dest=[::ffff:192.168.139.1]:56256 mark=0x0 length=32 snd_nxt=0xee4abe9c snd_una=0xee4abe9c snd_cwnd=10 ssthresh=2147483647 snd_wnd=29312 srtt=478 rcv_wnd=28992

I need your feedback for this change, like formatting etc.
Also, I need more test for this events by who can setup
DCCP and SCTP, since those are special protocols, I have
no environment to test it.

Steve, I also wrote a hack in sctp_probe event. Because
it requires to record several events at once, sctp_probe_path
events will be called from assignment code. This means
ring-buffer write will be recursively called (reserve-commit
pair will be recursed). As far as I can see, that seems OK.
But I need your review too.

Thank you,

---

Masami Hiramatsu (6):
      net: tcp: Add trace events for TCP congestion window tracing
      net: tcp: Remove TCP probe module
      net: sctp: Add SCTP ACK tracking trace event
      net: sctp: Remove debug SCTP probe module
      net: dccp: Add DCCP sendmsg trace event
      net: dccp: Remove dccpprobe module


 include/trace/events/sctp.h |   96 ++++++++++++++
 include/trace/events/tcp.h  |   96 ++++++++++++++
 net/Kconfig                 |   17 --
 net/core/net-traces.c       |    1 
 net/dccp/Kconfig            |   17 --
 net/dccp/Makefile           |    2 
 net/dccp/probe.c            |  203 -----------------------------
 net/dccp/proto.c            |    5 +
 net/dccp/trace.h            |  105 +++++++++++++++
 net/ipv4/Makefile           |    1 
 net/ipv4/tcp_input.c        |    4 +
 net/ipv4/tcp_probe.c        |  301 -------------------------------------------
 net/sctp/Kconfig            |   12 --
 net/sctp/Makefile           |    3 
 net/sctp/probe.c            |  244 -----------------------------------
 net/sctp/sm_statefuns.c     |    5 +
 16 files changed, 312 insertions(+), 800 deletions(-)
 create mode 100644 include/trace/events/sctp.h
 create mode 100644 include/trace/events/tcp.h
 delete mode 100644 net/dccp/probe.c
 create mode 100644 net/dccp/trace.h
 delete mode 100644 net/ipv4/tcp_probe.c
 delete mode 100644 net/sctp/probe.c

--
Masami Hiramatsu (Linaro) <mhiramat@...nel.org>