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

Nigel Cunningham
2005-09-19T06:54:35Z

Hi.

On Mon, 2005-09-19 at 16:36, Nick Piggin wrote:
> On Mon, 2005-09-19 at 14:37 +0800, Shaohua Li wrote:
> > On Mon, 2005-09-19 at 11:53 +0530, Srivatsa Vaddagiri wrote:
>
> > > default_idle should be fine as it is. IOW it should not cause __cpu_die to
> > > timeout.
> > Why default_idle should be fine? it can be preempted before the
> > 'local_irq_disable' check. Even with Nigel's patch, there is a very
> > small window at safe_halt (after 'sti' but before 'hlt').
> >
>
> Ah, actually I have a patch which makes all CPU idle threads
> run with preempt disabled and only enable preempt when scheduling.
> Would that help?

Sounds to me like it should, but I'm not claiming any expertise in this
area. Going off your other posts, you're thinking of this plus my
original patch?

Regards,

Nigel