[PATCH v2 15/45] rcu: Use get/put_online_cpus_atomic() to prevent CPU offline

[David Laight]

> Once stop_machine() is gone from the CPU offline path, we won't be able
> to depend on disabling preemption to prevent CPUs from going offline
> from under us.

Could you use an rcu-like sequence so that disabling pre-emption
would be enough?

Something like rebuilding the cpu list, then forcing yourself
to run on all the cpu.

That would be far less intrusive.

	David