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

From: Masami Hiramatsu
Date: Wed Nov 08 2017 - 05:00:35 EST


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@xxxxxxxxxx>