Re: PATCH: Fix race in cpu_down (hotplug cpu)

Srivatsa Vaddagiri
2005-09-19T05:11:06Z

On Mon, Sep 19, 2005 at 12:48:38PM +0800, Li, Shaohua wrote:
> I guess Nigel's point is cpu_idle is preempted before take_cpu_down. If
> the preempt occurs after the cpu_is_offline check, when the cpu (after

How can that happen? Idle task is running at max priority (MAX_RT_PRIO-1)
and with SCHED_FIFO policy at this point. If that is indeed happening,
then we need to modify sched_idle_next not to allow that.

> sched_idle_next) goes into idle again, nobody can wake it up. Nigel,
> isn't it?

--

Thanks and Regards,
Srivatsa Vaddagiri,
Linux Technology Center,
IBM Software Labs,
Bangalore, INDIA - 560017