Re: [PATCH 04/40] sched: implement __set_cpus_allowed()

Peter Zijlstra
2010-01-19T08:37:51Z

On Tue, 2010-01-19 at 10:07 +0900, Tejun Heo wrote:
>
> It's also necessary to guarantee forward progress during CPU_DOWN.
> The problem with kthread_bind() is that it's not synchronized against
> CPU hotplug operations. It needs outer synchronization like calling
> it directly from CPU_DOWN_PREP. I guess it's doable but I think it
> would be better to simply share the backend implementation between
> set_cpus_allowed_ptr() and kthread_bind().

OK, so you're saying you need to migrate the rescue thread during
cpu-down. That thread is guaranteed sleeping right, if it were not it'd
not be elegible to run on our dying cpu. Hence kthread_bind() ought to
just work, no?