Re: [PATCH] tcp: TCP_USER_TIMEOUT can not work in tcp_probe_timer()

On Tue, 2017-09-12 at 08:05 -0700, Eric Dumazet wrote:

On Tue, 2017-09-12 at 14:08 +0800, liujian wrote:

quoted

Hi,

In the scenario, tcp server side IP changed, and at that memont,
userspace application still send data continuously;
tcp_send_head(sk)'s timestamp always be refreshed.

Here is the packetdrill script:

   0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
   +0 bind(3, ..., ...) = 0
   +0 listen(3, 1) = 0

   +0 < S 0:0(0) win 0 <mss 1460,sackOK,nop,nop,nop,wscale 7>
   +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7>

  +.1 < . 1:1(0) ack 1 win 65530
   +0 accept(3, ..., ...) = 4

   +0 setsockopt(4, SOL_TCP, TCP_USER_TIMEOUT, [3000], 4) = 0
   +0 write(4, ..., 24) = 24
   +0 > P. 1:25(24) ack 1 win 229
   +.1 < . 1:1(0) ack 25 win 65530

//change the ipaddress
   +1 `ifconfig tun0 192.168.0.10/16`

   +1 write(4, ..., 24) = 24
   +1 write(4, ..., 24) = 24
   +1 write(4, ..., 24) = 24
   +1 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24
   +3 write(4, ..., 24) = 24

   +0 `ifconfig tun0 192.168.0.1/16`
   +0 < . 1:1(0) ack 1 win 1000
   +0 write(4, ..., 24) = -1

This has nothing to do with the code patch you have changed.

How have you tested your patch exactly ?

lpaa23:~# ss -toenmi src :8080
State      Recv-Q Send-Q Local Address:Port               Peer
Address:Port              
ESTAB      0      144    192.168.134.161:8080
192.0.2.1:51165               timer:(persist,8.262ms,5) ino:1
82083 sk:3 <->
	 skmem:(r0,rb359040,t0,tb46080,f1792,w2304,o0,bl0,d0) sack cubic
wscale:7,8 rto:301 backoff:5 rtt:100.127/37.576 
mss:1460 rcvmss:536 advmss:1460 cwnd:10 bytes_acked:24 segs_out:12
segs_in:3 data_segs_out:12 send 1.2Mbps lastsnd:1370 l
astrcv:13348 lastack:13248 pacing_rate 2.3Mbps delivery_rate 116.7Kbps
app_limited busy:11346ms rcv_space:29200 notsent:1
44 minrtt:100.043

This is the typical RTO timer, not zero window probe.