[PATCH] Fix bug #11375 - ordering issue in teardown in server exit.

[Jeremy Allison]

On Fri, Dec 04, 2015 at 01:46:20AM -0800, Richard Sharpe wrote:
> On Wed, Nov 25, 2015 at 8:51 AM, Jeremy Allison <jra at samba.org> wrote:
> > On Wed, Nov 25, 2015 at 01:05:11PM +0100, Stefan Metzmacher wrote:
> >> Am 25.11.2015 um 08:05 schrieb Stefan Metzmacher:
> >> > Hi Jeremy,
> >> >
> >> >> On Tue, Nov 24, 2015 at 10:09:39PM +0100, Stefan Metzmacher wrote:
> >> >>> smbXsrv_session_logoff() sets session->table = NULL;
> >> >>> and should exit immediately the 2nd time.
> >> >>> Am I missing something?
> >> >>>
> >> >>> This can only explained if it's NOT called twice,
> >> >>> but the first time AFTER sconn is already gone.
> >> >>
> >> >> Yes, you're right. It must be the first call
> >> >> after sconn is deleted.
> >> >>
> >> >>> A wild guess, could we have a bug in dbwrap_rbt traverse?
> >> >>> That may skip entries randomly?
> >> >>
> >> >> That's a tricky recursive function. Maybe.
> >> >> I'll take a close look....
> >> >
> >> > I added some tests. I started to write this mail
> >> > saying it all works, but I just got this:
> >> >
> >> > And the failure reproduces very often, but
> >> > valgrind doesn't give errors.
> >> >
> >> > I'd guess it's related to __rb_rotate_right and __rb_rotate_left
> >> > and our traverse code doesn't have this in mind.
> >> > I'm wondering if we need to somehow make use of rb_next(), rb_prev(),
> >> > rb_first() and rb_last().
> >>
> >> I don't understand that code and added a linked list that
> >> is used for the traverse.
> >
> > Great detective work Metze ! Congratulations.
> >
> > I'm out for US Thanksgiving until next week,
> > but I'll try and make some time between family
> > things to keep up on email/reviews.
> 
> Is it possible that this is the cause of
> https://bugzilla.samba.org/show_bug.cgi?id=11394 as well.
> 
> We seem to be able to hit this from time to time.
> 
> I will get someone to try Metze's patch to see if it resolves that problem.

Yeah that looks possible. I'm planning to add Metze's
fixes to the existing patch we have in the bug report.