[MPTCP] [Weekly meetings] MoM - 16th of April 2020

[MPTCP] [Weekly meetings] MoM - 16th of April 2020

[Matthieu Baerts]

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Hello,

We just had our 95th meeting with Mat and Ossama (Intel OTC), Christoph 
(Apple), Paolo, Davide and Florian (RedHat) and myself (Tessares).

Thanks again for this new good meeting!

Here are the minutes of the meeting:



Accepted patches:
     - The list of accepted patches can be seen on PatchWork:
       https://patchwork.ozlabs.org/project/mptcp/list/?state=3

     netdev (if mptcp ML is in cc) (by: Florian Westphal):

1269367: Deferred: [net] mptcp: fix double-unlock in mptcp_poll

     our repo (by: /):

/



Pending patches:
     - The list of pending patches can be seen on PatchWork:
       https://patchwork.ozlabs.org/project/mptcp/list/?state=*

     netdev (if mptcp ML is in cc) (by: Hillf Danton):

1269397: Rejected: Re: WARNING: bad unlock balance in mptcp_shutdown

     our repo (by: Davide Caratti, Florian Westphal, Matthieu Baerts, 
Paolo Abeni):

1265469: Needs Review / ACK: selftests:mptcp:pm: rm the right tmp file:
     - To be reviewed (one line)

1266897: Under Review: mptcp:pm netlink: fix variable scope:
     - Drop? Yes!

1271115: Changes Requested: [v2,1/4] uapi: update linux/mptcp.h
1271117: Changes Requested: [v2,2/4] add support for mptcp netlink 
interface.
1271119: Changes Requested: [v2,3/4] ss: allow dumping MPTCP subflow 
information
1271118: Changes Requested: [v2,4/4] man: mptcp man page:
     - v3 in preparation

1271341: New: [1/7] mptcp: fix splat when incoming connection is never 
accepted before exit/close
1271343: New: [2/7] mptcp: fix 'Attempt to release TCP socket in state' 
warnings
1271344: New: [3/7] mptcp: handle mptcp listener destruction via rcu
1271345: New: [4/7] mptcp: avoid callback invocation when mptcp parent 
socket doesn't exist
1271346: New: [5/7] mptcp: use rcu helpers to fetch ulp subflow context
1271347: New: [6/7] mptcp: reverse order of sk_state_change and is_mptcp 
check
1271348: New: [7/7] mptcp: prevent null deref crash on normal tcp sockets:
     - The 4th and 7th should go together
     - Raise condition regarding the 3rd ACK
     - Still investigating because the cause is still unclear, maybe 
there is another issue we would hide there
     - the first 3 patches can be applied, ACK from Paolo.
     - Matth can applied them at the end of the export branch
     - Florian can also send them directly to netdev (-net)



Bugs on Github:
    2: reduce hooking in TCP code → could go upstream before part 4
    4: keep a single work struct in mptcp socket → could go upstream 
before part 4
    5: Allow ss/netstat etc. to show program name for client and 
listener MPTCP subflows → could go upstream before part 4
    7: cleanup sendmsg_frag allocation
    8: fix possible race in subflow_finish_connect()
    9: fix "IPv4: Attempt to release TCP socket in state 1 "... on shutdown
   10: reduce mptcp options space usage
   11: fix fallback to TCP... @dcaratti
    3: fix 'mmap' related race
    6: loss and delay without reordering causes very slow transfer
   13: [syzkaller] WARNING in mptcp_incoming_options
   12: [syzkaller] INFO: task hung in lock_sock_nested



FYI: Current Roadmap:
     - Part 4 (next merge window):
         - Fix bugs reported on Github: 
https://github.com/multipath-tcp/mptcp_net-next/issues/
         - Shared recv window (full support)
         - IPv6 - IPv4 mapped support
         - not dropping MPTCP options (ADD_ADDR, etc.)
         - FAST_CLOSE
         - full MPTCP v1 support (reliable add_addr, etc.)
         - after a few attempts of failed MPTCP, we fallback to TCP 
(like TFO is doing)
         - PM server (more advanced)
         - Full DATA_FIN support [WIP by Mat]:
             - could be nice to have it: if ready
         - Active backup support
         - ADD_ADDR for MPTCPv1: echo bit [WIP by Peter]
         - Opti in TCP option structures (unions) [to be rebased]

     - Part 5 (extra needed for prod):
         - opti/perfs
         - TFO
         - PM netlink
         - PM bpf
         - Scheduler bpf
         - syncookies
         - [gs]etsockopt per subflow
         - notify the userspace when a subflow is added/removed → cmsg



Extra tests:
     - news about Syzkaller? (Christoph):
         - syzbot reported new issues on netdev, all already addressed
         - "WARNING in mptcp_incoming_options": but no reproducer

     - new about Intel's kbuild? (Mat):
         - there was a report this week but unclear if the errors were 
due to our modifications
         - 
https://lists.01.org/hyperkitty/list/mptcp(a)lists.01.org/thread/TLP3WL3AFXNXKORIT7JKQMSTNYBGIX2C/
         - Mat will follow-up

     - packetdrill (Davide):
         - could be nice to use this new version with the out-of-tree 
kernel!

     - CI (Matth):
         - /



Next meeting:
     - We propose to have the next meeting on Thursday, the 23rd of April.
     - Usual time: 16:00 UTC (9am PDT, 6pm CEST)
     - Still open to everyone!
     - https://annuel2.framapad.org/p/mptcp_upstreaming_20200423



Feel free to comment on these points and propose new ones for the next
meeting!

Talk to you next week,
Matt
-- 
Matthieu Baerts | R&D Engineer
matthieu.baerts(a)tessares.net
Tessares SA | Hybrid Access Solutions
www.tessares.net
1 Avenue Jean Monnet, 1348 Louvain-la-Neuve, Belgium