(no subject)

[Ian Jackson <ian.jackson@eu.citrix.com>]

This series removes the usleeps and waiting loops in libxl_dom.c and
replaces them with event-callback code.

Firstly, some documentation of things I had to reverse-engineer:
 01/23 xen: Document XEN_DOMCTL_subscribe
 02/23 xen: Document that EVTCHNOP_bind_interdomain signals
 03/23 docs: Document event-channel-based suspend protocol
 04/23 libxc: Document xenctrl.h event channel calls
Arguably these might be 4.4 material (hence the CC to George).

We want some additional libxl event facilities:
 05/23 libxl: init: Provide a gc later in libxl_ctx_alloc
 06/23 libxl: init: libxl__poller_init and _get take gc
 07/23 libxl: events: const-correct *_inuse, *_isregistered
 08/23 libxl: events: Provide libxl__xswait_*
 09/23 libxl: events: Use libxl__xswait_* in spawn code
 10/23 libxl: events: Provide libxl__ev_evtchn*

We need to clean up some unfortunate code in libxc:
 11/23 libxc: suspend: Rename, improve xc_suspend_evtchn_init
 12/23 libxc: suspend: Fix suspend event channel locking

We do some shuffling around of the libxl suspend control flow:
 13/23 libxl: suspend: Async libxl__domain_suspend_callback
 14/23 libxl: suspend: Async domain_suspend_callback_common
 15/23 libxl: suspend: Reorg domain_suspend_callback_common
 16/23 libxl: suspend: New libxl__domain_pvcontrol_xspath
 17/23 libxl: suspend: New domain_suspend_pvcontrol_acked
No functional change in those five.  These changes are broken down
just to make the changes reviewable.

Finally, we can start to work on the event code, removing the bugs,
usleeps and loops one at a time:
 18/23 libxl: suspend: domain_suspend_callback_common xs errs
 19/23 libxl: suspend: Async xenstore pvcontrol wait
 20/23 libxl: suspend: Abolish usleeps in domain suspend wait
 21/23 libxl: suspend: Fix suspend wait corner cases
 22/23 libxl: suspend: Async evtchn wait
 23/23 libxl: suspend: Apply guest timeout in evtchn case

I have tested this with a Debian pvops kernel (xenstore pvcontrol
suspend signalling) and OpenSUSE 11 (event channel suspend
signalling).

Shriram: I haven't really touched the Remus-specific code here but
this series ought to be suitable for you to base things on, assuming
my co-maintainers like the general approach.

Thanks,
Ian.