Created attachment 606196 [details]
Proposed patch

Description of problem:

When flushing, discard only memb_join messages

    Patch solves problem when 1 ring out of 2 went up/down quite often.

    The simplest setup to reproduce bug is following:
    - 2 VMs, connected by 2 network interfaces
    - OS: Linux
    - On one of the VMs, a test program sending some CPG messages (see the
      script "test_corosync.sh" joined to this mail for example)

    Here are the Corosync logs we get when we do this setup:

    Jun 06 16:23:40 corosync [TOTEM ] A processor joined or left the
    membership and a new membership was formed.
    Jun 06 16:23:40 corosync [CPG   ] chosen downlist: sender r(0)
    ip(192.168.56.104) r(1) ip(192.168.57.104) ; members(old:1 left:0)
    Jun 06 16:23:40 corosync [MAIN  ] Completed service synchronization,
    ready to provide service.
    Jun 06 16:24:37 corosync [TOTEM ] Marking ringid 1 interface
    192.168.57.105 FAULTY
    Jun 06 16:24:38 corosync [TOTEM ] Automatically recovered ring 1
    Jun 06 16:25:33 corosync [TOTEM ] Marking ringid 1 interface
    192.168.57.105 FAULTY
    Jun 06 16:25:34 corosync [TOTEM ] Automatically recovered ring 1
    Jun 06 16:26:35 corosync [TOTEM ] Marking ringid 1 interface
    192.168.57.105 FAULTY
    Jun 06 16:26:36 corosync [TOTEM ] Automatically recovered ring 1
    (...)

    The second ring goes down about every 2 minutes and automatically back
    up right after.

    We spent some times looking for the commit that introduced this bug, and
    it appears it's due the following one:
    Corosync 1.3.3 -> 1.3.4: e27a58d93d0d3795beb550f87b660c9c04f11386
    Corosync 1.4.1 -> 1.4.2: be608c050247e5f9c8266b8a0f9803cc0a3dc881
    Commit message: Ignore memb_join messages during flush operations

    I had a look at this commit, and it seems to me it's dropping too many
    packets:
    Because of this commit, while totemrrp_recv_flush() is called, Corosync
    drops memb_join packets, but also ORF tokens. In the end, it seems that
    sometimes, we drop so many of them that Corosync marks the ring as
    faulty.

    To fix that, only memb_join messages are dropped now.


How reproducible:
0.1%

Steps to Reproduce:
Described in description
  
Actual results:
Marking rrp interface as faulty too often

Expected results:
Oposite of actual results

Additional info:
For QE: Community patch, I was not able to reproduce it by myself.