OpenLDAP backend broken by the new ldb.tdb event context work, would appreciate advice on how to fix

[Nadezhda Ivanova]

Hi team and Andrew,
I'm trying to start using the newest Samba for my OpenLDAp backend work 
- after the long hiatus, I was using code that was 2 years old, so I 
decided to adapt to the newest master.
However, we are no longer able to provision an OpenLDAP backend - one of 
the issues I have a workaround for, by adding "client ldap sasl wrapping 
= plain" to my smb.conf, until I'm able to fix it properly, but the 
other I need some advice on.

While trying to create the domain naming context, provisioning hangs here:


#0  0x00007ffff78f1673 in __epoll_wait_nocancel () at 
../sysdeps/unix/syscall-template.S:81
#1  0x00007ffff5b0a074 in epoll_event_loop (epoll_ev=0x1ec7360, 
tvalp=0x7fffffffc640) at ../lib/tevent/tevent_epoll.c:642
#2  0x00007ffff5b0a98c in epoll_event_loop_once (ev=0x1ec70e0, 
location=0x7ffff64b0edd "../lib/ldb/common/ldb.c:637") at 
../lib/tevent/tevent_epoll.c:930
#3  0x00007ffff5b07693 in std_event_loop_once (ev=0x1ec70e0, 
location=0x7ffff64b0edd "../lib/ldb/common/ldb.c:637") at 
../lib/tevent/tevent_standard.c:114
#4  0x00007ffff5b0050f in _tevent_loop_once (ev=0x1ec70e0, 
location=0x7ffff64b0edd "../lib/ldb/common/ldb.c:637") at 
../lib/tevent/tevent.c:721
#5  0x00007ffff64a71bc in ldb_wait (handle=0x15a1fb0, type=LDB_WAIT_ALL) 
at ../lib/ldb/common/ldb.c:637
#6  0x00007fffda0d3d7e in new_partition_set_replicated_metadata 
(ldb=0x1c52460, module=0x1b77090, last_req=0x1d5a070, data=0x15f8bd0, 
partition=0x1c75bd0)
     at ../source4/dsdb/samdb/ldb_modules/partition_init.c:601
#7  0x00007fffda0d46da in partition_create (module=0x1b77090, 
req=0x174c980) at ../source4/dsdb/samdb/ldb_modules/partition_init.c:827
#8  0x00007fffda0d21e2 in partition_extended (module=0x1b77090, 
req=0x174c980) at ../source4/dsdb/samdb/ldb_modules/partition.c:1172
#9  0x00007ffff6488c42 in ldb_next_request (module=0x1b77090, 
request=0x174c980) at ../lib/ldb/common/ldb_modules.c:543
#10 0x00007fffdaefe427 in np_part_search_callback (req=0x2162590, 
ares=0x15a47a0) at ../source4/dsdb/samdb/ldb_modules/new_partition.c:143
#11 0x00007fffd6fd7275 in ltdb_request_done (ctx=0x1c9b4c0, error=32) at 
../lib/ldb/ldb_tdb/ldb_tdb.c:1314
#12 0x00007fffd6fd7556 in ltdb_callback (ev=0x1ec70e0, te=0x2303ba0, 
t=..., private_data=0x1c9b4c0) at ../lib/ldb/ldb_tdb/ldb_tdb.c:1424
#13 0x00007ffff5b08602 in tevent_common_loop_timer_delay (ev=0x1ec70e0) 
at ../lib/tevent/tevent_timed.c:369
#14 0x00007ffff5b0a90c in epoll_event_loop_once (ev=0x1ec70e0, 
location=0x7ffff64b0edd "../lib/ldb/common/ldb.c:637") at 
../lib/tevent/tevent_epoll.c:915
#15 0x00007ffff5b07693 in std_event_loop_once (ev=0x1ec70e0, 
location=0x7ffff64b0edd "../lib/ldb/common/ldb.c:637") at 
../lib/tevent/tevent_standard.c:114
#16 0x00007ffff5b0050f in _tevent_loop_once (ev=0x1ec70e0, 
location=0x7ffff64b0edd "../lib/ldb/common/ldb.c:637") at 
../lib/tevent/tevent.c:721
#17 0x00007ffff64a71bc in ldb_wait (handle=0x15af320, type=LDB_WAIT_ALL) 
at ../lib/ldb/common/ldb.c:637
#18 0x00007ffff68c4af2 in py_ldb_add (self=0x7fffde1f1eb0, 
args=0x7fffd647d908, kwargs=0x0) at ../lib/ldb/pyldb.c:1415
#19 0x0000000000523f6d in PyEval_EvalFrameEx ()
#20 0x0000000000555551 in PyEval_EvalCodeEx ()


This seems to start happening after this commit:

commit e67d3568e5853387d0675ed13d51df21e6274770
Author: Andrew Bartlett <abartlet at samba.org>
Date:   Fri May 12 02:30:01 2017 +0200

     ldb: Use the private event context in ldb_tdb and ldb_wait()

     This enables the previous commits, and ensures that ldb_tdb is safe 
from operations while locks
     are held

     Signed-off-by: Andrew Bartlett <abartlet at samba.org>
     Reviewed-by: Stefan Metzmacher <metze at samba.org>
     Reviewed-by: Garming Sam <garming at catalyst.net.nz>



Could you advise me on why this happens, and possible steps to fix?

Best Regards,
Nadya