https://fedorahosted.org/sssd/ticket/1869
Currently the private data passed to the PAM request is a structure
allocated on the client context. But in the odd case where the back end
would be stopped or stuck until the idle timeout hits, the DP callback.
This patch introduces a new structure allocated on responder context,
whose only purpose is to live as long as the request is active.
The attached patch is mostly a workaround, I think the correct fix would
be to start using a tevent_req-styled request structure similar to the one we
use in the NSS responder, but we've seen users hitting this problem even
on RHEL5 with sssd-1-5 recently, so I would like to fix the problem in
some way. If this patch is accepted, I'll file a ticket to convert the
PAM responder to a tevent_req interface for better manageability.