several wired errors with samba4

[Andrew Bartlett]

On Fri, 2009-02-27 at 12:04 +1100, Andrew Bartlett wrote:
> On Thu, 2009-02-26 at 16:14 +0300, Matthieu Patou wrote:
> > Hello andrew,
> > 
> > I added yesterday the trace and today I got several traces (today I had 
> > severals errors because a user has been using a bit more than usual the 
> > server) (but it's still underloaded).
> > 
> > 
> > > If you add a call to call_backtrace() in the case where we get this
> > > error (where you print the uid at the moment), then we can see what the
> > > call stack is, and try to debug this further.
> 
> Thank you *very* much. This is really, really useful debugging data.
> 
> In short, changing UIDs and nested event loops are a recipe for chaos. 
> 
> We need to not restart the main event loop in the
> wbc_xids_to_sids_recv() call, or rework the 'change to user' code to
> return to root before this call is made. 
> 
> If we must loop here, we should ensure we never call messaging_init(),
> but instead have the message context already ready.

It seems we do already have a messaging context for the wbc_xids_to_sids
call - it is the event loop that causes the problem, as this allows new
connections to be established (which need root, but don't have it).

Andrew Bartlett
-- 
Andrew Bartlett
http://samba.org/~abartlet/
Authentication Developer, Samba Team           http://samba.org
Samba Developer, Red Hat Inc.
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