[PATCH] rtasd cleanup

[Anton Blanchard]

Hi Nathan,

> Make rtasd stop (ab)using lock_cpu_hotplug and the online map.  Use a
> lazier method: let do_event_scan tell rtasd on which cpu the scan was
> done; rtasd then clears that cpu in its allowed map and migrates.
> This reduces boot time by one second per cpu when
> CONFIG_HOTPLUG_CPU=y.  (Sleeping for one second on each cpu while
> holding the cpucontrol semaphore is not very polite.)

We used to migrate to random cpus each iteration but we got watchdog
timeouts on a 16 way nighthawk. The theory was that the worst case touch
of the watchdog on a cpu could be 2x the scan rate.

I didnt confirm this with the firmware guys but changing it to the
current method where we always iterate in the same order made the
watchdogs go away.

Anton