Re: (ITS#5451) syncprov_checkpoint deadlock bugfix?

[hyc@symas.com]

rein@tollevik.no wrote:
> On Wed, 9 Apr 2008, h.b.furuseth@usit.uio.no wrote:
>
>> Does this help?  From my fiddling with ITS#5340 (REP_ENTRY_MODIFIABLE).
>> I do not understand syncprov's handling of REP_ENTRY_MUSTRELEASE though.
>> (For one thing it seems to assume that REP_ENTRY_MUSTRELEASE is set if
>> and only if rs.sr_entry->e_private != NULL.  Which is possibly true with
>> back-bdb but seems a shaky assumption in general.)
>
> Almost, except that it triggers an abort..  Using be_entry_release_r() was
> not correct, as it ended up calling entry_free().  It works if I changes
> it to use overlay_entry_release_ov() instead, as in the alternative patch
> at the end.
>
> I have put a test script that shows this deadlock on:
>
>    ftp://ftp.openldap.org/incoming/test053-syncprov-glue
>
> It deadlocks without this patch, it and the rest of the test suite succeed
> with it :-)  I haven't tested it in production though..

This last patch is now committed to HEAD. I am ignoring the first patch; it is 
unsafe because it unlocks the si_csn_rwlock too soon. (si_ctxcsn is being used 
directly in the modify request and must be held consistent until that completes.)

-- 
   -- Howard Chu
   CTO, Symas Corp.           http://www.symas.com
   Director, Highland Sun     http://highlandsun.com/hyc/
   Chief Architect, OpenLDAP  http://www.openldap.org/project/