On 11/09/14 11:59, Petr Spacek wrote:
Hello,
I was fighting with random crashes for couple of days ... and
discovered that run_exclusive_enter()/isc_task_beginexclusive() usage
was completely incorrect and didn't actually lock anything.
This series of patches reworks internal locking (and related event
system) to work around limitations of isc_task_beginexclusive()
mechanism.
It would be better to get rid of isc_task_beginexclusive() completely
but IMHO it is not possible because of BIND's dns_view*() functions
have to be guarded with it.
Testing is going to be interesting because we are speaking about race
conditions.
I used ~ 100 DNS zones, each zone had ~ 100 random domain names inside
with random A/AAAA/TXT RRs. My LDIF is here:
http://people.redhat.com/~pspacek/a/2014/09/11/dns-test.ldif.xz
I was able to randomly reproduce various crashes when BIND was running
with more threads than usually.
You can try to run BIND with this command (as root) and play games
with -n parameter:
$ export KRB5_KTNAME="/etc/named.keytab"
$ named -4 -g -u named -m record -n 10
Please test also the case where BIND receives SIGINT during start-up.
It is possible to run BIND with commands above and wait for message:
11-Sep-2014 11:54:58.092 running
At this point send SIGINT (CTRL+C) to BIND and see what happens. It
could crash or deadlock.
It is necessary to send the signal before BIND prints this message:
11-Sep-2014 11:55:11.707 zone z1.test/IN: loaded serial 1410429304
Let me know if you need any assistance.
I need your assistance, I haven't been able to reproduce it.
Martin
--
Martin Basti
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