[CRIU] criu + threaded program + TCP_REPAIR

[Sowmini Varadhan]

Hello,

I wanted to observe the TCP_REPAIR code in action, to get a better
understanding of it. So I tried the following in a qemu-kvm
env, but I'm running into some errors- not sure if I'm hitting something
that is not supported yet, or if I have some user-error.

1. Start the server in vm1.
     server# nohup iperf -s &

2. start the client, and set up parameters so that it runs for a long time
      client# iperf -c <srvaddr> -P 10 -t 900

3. Checkpoint the server
      server# criu dump -D .  -t 10186 --shell-job --tcp-established --shel-job

4. Add the server's address on dummy0 on the client
      client# ip link add dummy0 type dummy
      client# ip addr add <srvaddr>  dev dummy0

5. Copy the checkpoint files over to the client (duplicate the dir structure)
   and restore

       client# criu restore -v4 --tree 10186 --images-dir /root/images \
                         --tcp-established --shell-job

I get the error

     :
    pie: Restoring EXE link
    pie: Restoring scheduler params 0.0.0
    pie: Restoring scheduler params 0.0.0
    pie: Error (pie/restorer.c:351): Thread pid mismatch 10189/10188
    pie: Restoring scheduler params 0.0.0
    pie: Error (pie/restorer.c:392): Restorer abnormal termination for 101>
    pie: 86
    (00.138423) Error (cr-restore.c:1812): Restoring FAILED.

I suspect this is being triggered by the fact that iperf is threaded-
am I right? What't the correct way to get this to restore?